WO2009126167A1

WO2009126167A1 - Optical data recording media and methods for recording and reading data thereon

Info

Publication number: WO2009126167A1
Application number: PCT/US2008/060143
Authority: WO
Inventors: Makarand P. Gore; Charles R. Weirauch; Jitka Brynjolffssen; Richard Lione
Original assignee: Hewlett-Packard Development Company, L.P.
Priority date: 2008-04-11
Filing date: 2008-04-11
Publication date: 2009-10-15
Also published as: TW200949832A

Abstract

An optical data recording medium (100) includes a substrate (220) and a markable coating (230) established on the substrate (220). The coating (230) includes an absorber (239) and a contrast agent (240). The absorber (239) is configured to absorb light of a first wavelength, and the contrast agent (240) is configured to undergo a chemical or physical change upon receiving energy from the absorber (239), thereby producing an optically detectable mark (242). The optically detectable mark (242) generates at least one of 1 ) a pattern that is readable with light of a second wavelength that is at least 200 nm apart from the first wavelength or 2) a pattern that is readable with light of the first wavelength.

Description

OPTICAL DATA RECORDING MEDIA AND METHODS FOR RECORDING AND READING DATA THEREON

BACKGROUND The present disclosure relates generally to optical data recording media, and methods for recording and reading data thereon.

Materials that produce color and/or contrast change upon stimulation with radiation are used in optical recording and imaging media and devices. Further, widespread adoption of and rapid advances in technologies relating to optical recording and imaging media have created a desire for greatly increased data storage capacity in such media. Thus, optical storage technology has evolved from the compact disc (CD) and laser disc (LD) to far denser data types such as digital versatile disc (DVD) and blue laser formats such as BLU-RAY and high-density DVD (HD-DVD). "BLU-RAY" and the BLU-RAY Disc logo mark are trademarks of the BLU-RAY Disc Founders, which consists of 13 companies in Japan, Korea, Europe, and the U.S.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of embodiments of the present disclosure will become apparent by reference to the following detailed description and drawings, in which like reference numerals correspond to similar, though perhaps not identical, components. For the sake of brevity, reference numerals or features having a previously described function may or may not be described in connection with other drawings in which they appear. Figure 1 is a semi-schematic perspective view and block diagram illustrating an embodiment of an optical disc recording system;

Figure 2 is a schematic side elevation view of an embodiment of a recording medium shown in conjunction with a partial block diagram of some of the elements of the system represented in Fig. 1 ;

Figure 3 is a graph depicting 2.4x modulation I14/I14H versus laser power for dye and absorber systems recorded at 405 nm and at 658 nm;

Figure 4 is a graph depicting 2.4x Jitter versus laser power for dye and absorber systems recorded at 405 nm and at 658 nm; Figure 5 is a graph depicting read stability (i.e., DC Jitter % versus number of read cycles) for dye and absorber systems recorded at 405 nm and at 658 nm; and

Figure 6 is a graph depicting the absorbance spectrum of a dye system and a dye and absorber system.

DETAILED DESCRIPTION

Embodiments of the optical recording/reading media and system disclosed herein may be described by the wavelengths.

In one embodiment of such systems, a first wavelength is used to write data that is readable in a second wavelength, which is at least 200 nm apart from the first/write wavelength. It has been found that the media/systems disclosed herein that enable recording/writing at one wavelength and reading at another wavelength are more stable to read processes than other media/systems. In the dual wavelength system, the recording medium includes one component that is highly absorbing at a first wavelength. The absorbed energy is transferred to another component, resulting in a chemical and/or physical change in the other component that forms an optically detectable mark that is advantageously readable at another wavelength that is at least 200 nm apart from the first wavelength.

In another embodiment of such systems, a single wavelength is used to write and read data. It has been found that the media/systems disclosed herein that enable recording/writing and reading at one wavelength unexpectedly utilize a contrast agent that has minimal absorbance at the recording and reading wavelength. In the single wavelength system, the recording medium includes one component that is highly absorbing at the desirable wavelength, and the contrast agent that is minimally absorbing at desirable wavelength. The absorbed energy is transferred to the contrast agent, resulting in a chemical and/or physical change in the contrast agent that forms an optically detectable mark that is readable at the recording/writing wavelength.

Both the single and dual wavelength systems disclosed herein are suitable for forming optically detectable marks at desirable wavelengths. Without being bound to any theory, it is believed that the mechanism for obtaining marks includes 1 ) changing the nature of the complex between the selected absorber and contrast agent, 2) physically changing the markable coating via pit formation (e.g., the absorber is displaced within the coating), 3) physically changing the thickness of portions of the markable coating (i.e., changing the depth of the distance traveled by the reading light), or combinations of 1 , 2 and 3.

Certain terms are used throughout the following description and claims that refer to particular system components. As one skilled in the art will appreciate, various companies may refer to a particular component by different names. This document does not intend to distinguish between components that differ in name but not function.

Reference is made herein to BLU-RAY technologies. Disc specifications for BLU-RAY discs currently include the following: wavelength = 405 nm; numerical aperture (NA) = 0.85; disc diameter = 12 cm; disc thickness = 1.2 mm; and data capacity > 23.3/25/27 GB. BLU-RAY discs can currently be used to store 2 hours of high resolution video images or 13 hours of conventional video images. A blue- violet laser having a wavelength between 380 nm and 420 nm, and particularly 405 nm is used as the light source for BLU-RAY discs. Another technology using blue light (380 nm ~ 420 nm radiation) is HD-DVD and ultra density optical (UDO) discs. As used herein, the terms "wavelength", "wave band", "absorption band" or "band" refer to light frequencies, radiation, and/or absorption ± 30 nm from the stated value. For example, the 405 nm band includes wavelengths ranging from 375 nm to 435 nm, and the 650 nm band includes wavelengths ranging from 620 nm to 680 nm.

The system disclosed herein may be defined by the wavelengths. In one embodiment, the first of the defining wavelengths is used to write data and a second of the defining wavelengths is at least 200 nm from the first wavelength and is used to read data. In another embodiment, the defining wavelength is used to write data and to read data. Color may be used to refer to the wavelengths for the media and system. For example, media disclosed herein that use the 405 nm 'blue' band to write on the media, and the 650 nm 'red' band to read the media may be referred to as "Write Blue-Read Red".

As used herein, the term "contrast agent" is defined as any material that, in conjunction with an absorber will produce contrast in the desired read band due to physical or chemical changes. The contrast agent may be a leuco dye, a combination of a leuco dye and a developer/developer precursor, or another material that undergoes changes in absorption coefficient (k), changes in refractive index (n), changes in reflectivity (r), changes in coating dimension (e.g., thickness), distortion, or a combination thereof.

The term "absorber", as used herein, describes a substance that absorbs a predetermined wavelength or range of wavelengths and transfers the absorbed energy to the contrast agent, thereby causing the contrast agent to alter its chemical and/or physical structure and produce an optically detectable change. In some instances, the absorber functions as the developer of the selected leuco dye.

"Leuco dye", as used herein, refers to a color- or contrast-forming substance that is colorless or exhibits one contrast in a non-activated state and that produces or changes contrast in an activated state. As used herein, the terms "developer" and "activator" describe a substance that reacts with the dye and causes the dye to alter its chemical structure and change or acquire color.

The term "light" as used herein includes electromagnetic radiation of any wavelength or band and from any source. Both the dual and single optical data recording medium 100 (shown in

Figures 1 and 2) disclosed herein may be used to record optical data or visual images, which then transmit readable patterns when exposed to light beams of a predetermined wavelength. The system used to write and/or read such data is shown in Fig. 1 and includes optical components 148, a light source 150 that produces an incident energy beam 152, a return beam 154 which is detected by a pickup 157, and a transmitted beam 156. In the transmissive optical disc form, the transmitted beam 156 is detected by a top detector 158 (a non-limiting example of which is a photo detector) via lens or optical system 600, and is also analyzed for the presence of signal agents. It is to be understood that Figure 2 shows an abbreviated block diagram of the read/write system 170 illustrating some of the same optical components shown in Figure 1.

In some embodiments, the system 170 includes one light source 150 that is able to emit the write wavelengths when desirable, and the read wavelengths when desirable. In other embodiments, the system 170 includes a light source 150 that emits write wavelengths and a separate light source (not shown) that emits read wavelengths. The separate write and read light sources are particularly suitable for the dual wavelength optical media.

Figure 1 also illustrates a drive motor 162 and a controller 164 for controlling the rotation of the optical disc/imaging medium 100. Mark(s) (shown as 242 in Figure 2) may be read/detected by an optical sensor (e.g., optical pickup 157). The sensor (e.g., optical pickup 157) is positioned so as to detect at least one readable pattern of the optically detectable mark(s) 242 on the imaging medium 100. Generally, the sensor reads at least one readable pattern as the imaging medium 100 moves in relation to the sensor. A laser beam of the sensor is focused on the marked surface and records changes in the reflected beam. The sensor may send the readable pattern in the form of one or more signals to a processor 166.

The processor 166 and an analyzer 168 may be implemented together or in the alternative for processing the return beam 154 with a signal 165 from the pickup 157 to the processor 166, as well as processing a transmitted beam 156 from a signal 163 transmitted from the optical detector 158 and associated with the transmissive optical disc format. A display monitor 114 is also provided for displaying the results (generally in the form of data) of the processing. The system may also include a computer data base (not shown) which collects and stores the processed/analyzed data for subsequent retrieval.

Figure 2 shows an abbreviated block diagram of the read/write system 170 illustrating some of the same optical components shown in Figure 1. Specifically, Figure 2 illustrates the read/write system 170 applying an incident energy beam 152 onto the imaging medium 100. The single and the dual wavelength imaging medium 100 include a substrate 220 and a marking layer (i.e., markable coating) 230 on a surface 222 thereof. In the embodiment shown, imaging medium 100 further includes a protective layer 235, such as is generally known. It is to be understood, however, that other embodiments of the imaging medium 100 do not include such a protective layer 235.

As described in detail below, marking layer 230 includes a color-forming agent or contrast agent 240 and an absorber 239 suspended or dissolved or finely dispersed in a matrix or binder. In some cases, the contrast agent 240 and the absorber 239 are completely soluble in the coating matrix or binder. In an embodiment, the marking layer 230 may also include a polymeric matrix and may also include an optional fixing agent (not shown).

The substrate 220 for the single or dual wavelength imaging medium 100 may be any substrate upon which it is desirable to make a mark 242, such as, for example, the polymeric substrate used in conventional CD-R/RW/ROM, DVD±R/RW/ROM, HD-DVD or BLU-RAY disc. Substrate 220 may be paper (e.g., labels, tickets, receipts, or stationery), overhead transparency, or other surface upon which it is desirable to provide marks. Marking layer 230 may be applied to the substrate 220 via any acceptable method, such as, for example, rolling, spin- coating, spraying, lithography, or screen printing.

In many embodiments, it may be desirable to provide a marking layer 230 that has a thickness equal to or less than 100 nm. In order to achieve this, spin coating is one suitable application technique. In addition, it may be desirable to provide a marking composition that is capable of forming a layer 230 that is equal to or less than 100 nm thick. In such cases, the marking layer 230 should be, inter alia, free from particles that would prevent formation of such a layer, i.e., free from particles having a dimension greater than 100 nm. In some instances, the components of the layer 230 may be in complete solution, thereby producing molecular level film aggregates. Furthermore, in many applications it may be desirable to provide a markable coating/marking layer 230 that is transparent. In such a case, any particles present in the coating 230 would have an average size less than half of the wavelength of the light to which the coating is transparent. While a coating 230 in which all particles are smaller than 150 nm would serve this purpose, it may be more desirable to utilize a coating 230 in which the marking components are dissolved, as opposed to one in which they are present as particles. Still further, as target data densities increase, the dot size, or mark size, that can be used for data recording decreases. Some currently available technologies require an average dot size of 150 nm or less. For all of these reasons, marking layer 230 is therefore desirably entirely free of particles that are larger than half the wavelength of the write radiation.

The color-forming agent or contrast agent 240 may be any substance that undergoes a detectable optical change in response to a threshold stimulus, which may be applied in the form of light or heat. In some embodiments, the contrast agent 240 includes a leuco dye and a developer (which may also function as the absorber 239), as described in detail below. The developer and the leuco dye produce a detectable optical change when chemically mixed. In other instances, the contrast agent 240 includes a material that, when exposed to energy absorbed by the absorber 239, undergoes changes in absorption coefficient (k), changes in refractive index (n), changes in reflectivity (r), changes in coating dimension (e.g., thickness), distortion, or a combination thereof. In one embodiment, it is believed that such changes are detectable at the desirable read wavelength (e.g., in the dual wavelength system, at least 200 nm from the write wavelength) and are the result of the decomposition of the contrast agent 240. In some cases, the absorbance of the material in the recorded mark 242 is essentially destroyed, and the dark mark 242 is due to light interference. Generally, the concentration and distribution of the contrast agent 240 in marking layer 230 are preferably sufficient to produce a detectable mark 242 when activated. In embodiments in which the markable coating 230 includes the developer and the leuco dye, both components may be soluble in the matrix. In other embodiments, one of the components may be suspended in the matrix as distributed particles, but homogenous coatings are preferred.

In a marking layer 230 in which both the developer and the leuco dye are dissolved, it may be desirable to prevent the components from combining prematurely and generating an optical change across the entire marking layer 230. This may be accomplished by incorporating one of the components of the contrast agent 240 in marking layer 230 as a precursor of that component. In these embodiments, the incident light or heat triggers a chemical change in the precursor, causing it to become the desired component. Once the desired component is formed, both components will be present locally and the contrast- forming reaction occurs. Thus, if energy of the write wavelength is applied to the desired region of marking layer 230, an optically detectable mark 242 can be produced. In the present application, this is accomplished by using a developer precursor in close proximity with the dye in the marking layer 230. The developer precursor does not become active as a developer until it has absorbed a stimulus which causes it to chemically rearrange. As such, the developer precursor may also function as the absorber 239. After this rearrangement, it can function as a developer as it comes in contact with the dye. As such, the matrix may be provided as a homogeneous, single-phase solution at ambient conditions because the use of a precursor for the developer prevents the color-forming/contrast reaction from occurring prior to activation. Nonetheless, in other embodiments, one or the other of the components may be substantially insoluble in the matrix at ambient conditions. By "substantially insoluble," it is meant that the solubility of that component of the contrast agent 240 in the matrix at ambient conditions is so low, that no or very little contrast change occurs due to reaction of the dye and the developer at ambient conditions. Thus, in some embodiments, the developer is dissolved in the matrix with the dye being present as small crystals suspended in the matrix at ambient conditions; while in other embodiments, the dye is dissolved in the matrix and the developer is present as small crystals suspended in the matrix at ambient conditions. The particle size is preferably less than 150 nm. Depending on the contrast agent 240 selected, the marking composition may become relatively more or relatively less absorbing at a desired wavelength upon activation. A single wavelength of light for both read and write operations often results in a contrast agent 240 that produces a mark 242 that is relatively darker (relative to the unmarked regions), for reading at the same wavelength or within the same wavelength range that is used for writing. In many contexts (including reading and writing at the 405 nm waveband, as described with the single wavelength system), it is desirable and convenient to provide a contrast agent 240 that, when exposed to a relatively narrow wavelength range, produces a mark 242 that is relatively absorbing at the same relatively narrow wavelength range for reading.

Additionally, the present applicants have improved on this paradigm. It is believed that more versatility in the contrast agent 240 may, in some instances, be desirable. When data or images are being read at the same wavelength that is used for writing (i.e., the energy of which causes the contrast agent 240 to physically and/or chemically change) the reading process may alter the results of the writing process. The applicants have found advantages in the use of absorbers 239 that absorb for writing purposes in a first wavelength band (e.g., from 380 nm to 420 nm), and contrast agents 240 that generate optically detectable marks 242 that absorb light (and thus are readable) at wavelengths that are at least 200 nm apart from the writing wavelengths. Such read band wavelengths may be as high as 650 nm or 780 nm or 900 nm. Therefore, when these data or images are read, they are not being read at the same optical wavelength used for the writing process that causes the contrast agent 240 to change. Thus, the chances of the reading process altering the results of the writing process are substantially minimized, or eliminated with the dual wavelength system. This is especially useful and important in high precision data writing. It is believed that writing and reading at different wavelengths enables better control and higher scope to be achieved in data writing and reading. Some of the advantageous features of such systems and methods are scatterless optical contrast and superior data storage capacity.

When it is desired to make a mark 242, marking energy 110 is directed in a desired manner at imaging medium 100. The form of the energy may vary depending upon the equipment available, ambient conditions, and desired result. Examples of energy that may be used include, but are not limited to, infra-red (IR) radiation, ultra-violet (UV) radiation, x-rays, or visible light. In these embodiments, imaging medium 230 is illuminated with light having the desired predetermined wavelength at the location where it is desired to form a mark 242. The absorber 239 in the marking layer 230 absorbs the energy, causing some physical and/or chemical change in the contrast agent 240, resulting in an optically detectable mark 242. It is to be understood that the resulting mark 242 can be detected by an optical sensor.

It is to be understood that the particular materials selected for the absorber 239 and contrast agent 240 and/or the concentration or ratio of such materials enables the formation of either the single wavelength system or the dual wavelength system.

Very generally, when forming the single wavelength recording medium 100, an absorber 239 that is highly absorbing at the desirable wavelength and a contrast agent 240 that exhibits minimal absorbance at the desirable wavelength are selected. As used herein, a "minimally absorbing" component refers to a component having less than 20% absorbance in a given wavelength as compared to the maximum absorption at any wavelength (λ_max) between 200 nm and 900 nm. For example, CIBA's® IRGAPHOR® 1699 has high absorbance at the 650 nm band, and minimal absorbance at the 405 nm band. Similarly, a "highly absorbing" component refers to a component that has an extinction coefficient of >10,000 at the wavelength of maximum absorption. For example, C.I. Solvent Yellow 93, is a strong is highly absorbing at the 405 nm band with an extinction coefficient of >50,000. When forming the dual wavelength recording medium 100, an absorber 239 that absorbs at the write wavelength and a contrast agent 240 that, after undergoing a physical or chemical change in response to energy from the absorber

239, absorbs at the read wavelength are selected. As a non-limiting example of the dual wavelength system, a mixture of IRGAPHOR® 1699 and Yellow 93 in a ratio 9:1 is sufficient to produce a coating with sensitivity at 405 nm for writing, and good readability at 650 nm.

As previously mentioned, the absorber 239 in the marking layer 230 absorbs the energy and transfers the energy within the layer 230 to the contrast agent 240. The transferred energy triggers a chemical or physical change in the contrast agent

240. In some instances, the energy causes the developer precursor to convert to the developer and activate the leuco dye. In other instances, the energy causes the contrast agent 240 to experience absorption coefficient changes, refractive index changes, reflectivity changes, dimension (e.g., thickness) changes, or distortion. The activation or change(s) produces an optically detectable mark 242, which may manifest itself in the form of a produced color, a color change and/or a change in the contrast of the layer 230. Thus, if energy is applied to a desired region of the marking layer 230, an optically detectable mark 242 may be produced.

Non-limiting examples of absorbers 239 with absorption at or near 405 nm (e.g., from about 375 nm to about 435 nm), and thus are suitable for use as the absorber 239 in both the single and dual wavelength systems, include curcumin; crocetin; porphyrin and derivatives thereof (e.g., etioporphyrin 1 (CAS 448-71-5), octaethyl porphyrin (CAS 2683-82-1 ), and deuteroporphyrin IX 2,4 bis ethylene glycol (D630-9), available from Frontier Scientific); azo dyes (e.g., Mordant Orange (CAS 2243-76-7), Methyl Yellow (CAS 60-11 -7), 4-phenylazoaniline (CAS 60-09- 3), and Alcian Yellow (CAS 61968-76-1 )); C.I. Solvent Yellow 93; C.I. Solvent Yellow 163; 1 ,3-dimethyl-5-[2-(1 -methyl-pyrrolidin-2-ylidene)-ethylidene]- pyrimidine-2,4,6-trione; 1 ,3-dimethyl-5-[2-(3-methyl-oxazolidin-2-ylidene)- ethylidene]-pyrimidine-2,4,6-thone; or the like. Still other suitable examples include 1-(2-chloro-5-sulfophenyl)-3-methyl-4-(4~sulfophenyl)azo-2-pyrazolin-5-one disodium salt (λ_max = 400 nm); ethyl 7-diethylaminocoumarin-3-carboxylate (λ_max = 418 nm) (CAS 28705-46-6); 3,3'-diethylthiacyanine ethylsulfate (λ_max = 424 nm) (CAS 2602-17-7); 3-allyl-5-(3-ethyl-4-methyl-2-thiazolinylidene) rhodanine (λ_max = 430 nm) (CAS 203785-75-5), (each of which is available from Organica Feinchemie GmbH Wolfen), or mixtures thereof. Non-limiting specific examples of suitable aluminum quinoline complexes that may be used as absorber 239 include tris(8-hydroxyquinolinato)aluminum (CAS 2085-33-8) and derivatives such as tris(5-cholor-8-hydroxyquinolinato)aluminum (CAS 4154-66-1 ); 2-(4-(1-methyl- ethyl)-phenyl)-6-phenyl-4H-thiopyran-4-ylidene)-propanedinitril-1 , 1 -dioxide (CAS 174493-15-3); 4,4'-[1 ,4-phenylenebis(1 ,3,4-oxadiazole-5,2-diyl)]bis N,N-diphenyl benzeneamine (CAS 184101-38-0); bis-tetraethylammonium-bis(1 ,2-dicyano- dithiolto)-zinc(ll) (CAS 21312-70-9); or 2-(4,5-dihydronaphtho[1 ,2-d]-1 ,3-dithiol-2- ylidene)-4,5-dihydro-naphtho[1 ,2-d]1 ,3-dithiole, all of which are available from Syntec GmbH.

As previously mentioned, in some instances, the contrast agent 240 includes a leuco dye and a developer precursor (which may be the absorber 239). A non-limiting example of a dual wavelength markable coating 230 having a leuco dye contrast agent 240 and a developer precursor absorber 239 includes curcumin diacetate (absorber 239) for the 405 nm band writing processes and Noveon Specialty Cyan 39 (contrast agent 240) for 650 nm reading processes.

Specific examples of other suitable leuco dyes for the dual and single wavelength system include fluorans and phthalides, which include but are not limited to the following (which may be used alone or in combination): 1 ,2-benzo-6- (N-ethyl-N-toluidino)fluoran, 1 ,2-benzo-6-(N-methyl-N-cyclohexylamino)fluoran, 1 ,2-benzo-6-dibutylaminofluoran, 1 ,2-benzo-6-diethylaminofluran, 2-(. alpha. - phenylethylamino)-6-(N-ethyl-p-toluidino)fluoran, 2-(2,3-dichloroanilino)-3-chloro-6- diethylaminofluran, 2-(2,4-dimethylanilino)-3-methyl-6-diethylaminofluoran, 2-(di-p- methylbenzilamino)-6-(N-ethyl-p-toluidino)fluoran, 2-(m-trichloromethylanilino)-3- methyl-6-(N-cyclohexyl-N-methylamino)fluoran, 2-(m-trichloromethylanilino)-3- methyl-6-diethylanimofluoran, 2-(m-trifluoromethylaniline)-6-diethylaminofluoran, 2- (m-trifluoromethylanilino)-3-chloro-6-diethylaminofluran, 2-(m- trifluoromethylanilino)-3-methyl-6-diethylanimofluoran, 2-(N-ethyl-p-toluidino)-3- methyl-6-(N-ethylanilino)fluoran, 2-(N-ethyl-p-toluidino)-3-methyl-6-(N-propyl-p- toluidino) fluoran, 2-(o-chloroanilino)-3-chloro-6-diethlaminofluoran, 2-(o- chloroanilino)-6-dibutylaminofluoran, 2-(o-chloroanilino)-6-diethylaminofluoran, 2- (p-acetylanilino)-6-(N-n-amyl-N-n-butylamino)fluoran, 2,3-dimethyl-6- dimethylaminofluoran, 2-amino-6-(N-ethyl-2,4-dimethylanilino)fluoran, 2-amino-6- (N-ethylanilino)fluoran, 2-amino-6-(N-ethyl-p-chloroanilino)fluoran, 2-amino-6-(N- ethyl-p-ethylanilino)fluoran, 2-amino-6-(N-ethyl-p-toluidino)fluoran, 2-amino-6-(N- methyl-2,4-dimethylanilino)fluoran, 2-amino-6-(N-methylanilino)fluoran, 2-amino-6- (N-methyl-p-chloroanilino)fluoran, 2-amino-6-(N-methyl-p-ethylanilino)fluoran, 2- amino-6-(N-methyl-p-toluidino)fluoran, 2-amino-6-(N-propyl-2,4- dimethylanilino)fluoran, 2-amino-6-(N-propylanilino)fluoran, 2-amino-6-(N-propyl-p- chloroanilino)fluoran, 2-amino-6-(N-propyl-p-ethylanilino)fluoran, 2-amino-6-(N- propyl-p-toluidino)fluoran, 2-anilino-3-chloro-6-diethylaminofluran, 2-anilino-3- methyl-6-(N-cyclohexyl-N-methylamino)fluoran, 2-anilino-3-methyl-6-(N-ethyl-N- isoamylamino)fluoran, 2-anilino-3-methyl-6-(N-ethyl-N-p-benzyl)aminofluoran, 2- anilino-3-methyl-6-(N-ethyl-N-propylamino)fluoran, 2-anilino-3-methyl-6-(N-iso- amyl-N-ethylamino)fluoran, 2-anilino-3-methyl-6-(N-isobutyl-methyl amino)fluoran, 2-anilino-3-methyl-6-(N-isopropyl-methyl amino)fluoran, 2-anilino-3-methyl-6-(N- methyl-p-toluidino-)fluoran, 2-anilino-3-methyl-6-(N-n-amyl-N-ethylamino)fluoran, 2- anilino-3-methyl-6-(N-n-amyl-N-methylamino)fluoran, 2-anilino-3-methyl-6-(N-n- propyl-N-isopropylamino)fluoran, 2-anilino-3-methyl-6-(N-n-propyl-N- methylamino)fluoran, 2-anilino-3-methyl-6-(N-sec-butyl-N-methylamino)fluoran, 2- anilino-3-methyl-6-diethylaminofluoran, 2-anilino-3-methyl-6-di-n-butylaminofluoran, 2-anilino-6-(N-n-hexyl-N-ethylamino)fluoran, 2-benzilamino-6-(N-ethyl-2,4- dimethylanilino)fluoran, 2-benzilamino-6-(N-ethyl-p-toluidino)fluoran, 2- benzilamino-6-(N-methyl-2,4-dimethylanilino)fluoran, 2-benzilamino-6-(N-methyl-p- toluidino)fluoran, 2-bromo-6-diethylaminofluoran, 2-chloro-3-methyl-6- diethylaminofluran, 2-chloro-6-(N-ethyl-N-isoamylamino)fluoran, 2-chloro-6- diethylaminofluoran, 2-chloro-6-dipropylaminofluoran, 2-diethylamino-6-(N-ethyl-p- toluidino)fluoran, 2-diethylamino-6-(N-methyl-p-toluidino)fluoran, 2-dimethylamino- 6-(N-ethylanilino)fluoran, 2-dimethylamino-6-(N-methylanilino)fluoran, 2- dipropylamino-6-(N-ethylanilino)fluoran, 2-dipropylamino-6-(N- methylanilino)fluoran, 2-ethylamino-6-(N-ethyl-2,4-dimethylanilino)fluoran, 2- ethylamino-6-(N-methyl-p-toluidino)fluoran, 2-methylamino-6-(N- ethylanilino)fluoran, 2-methylamino-6-(N-methyl-2,4-dimethylanilino)fluoran, 2- methylamino-6-(N-methylanilino)fluoran, 2-methylamino-6-(N-propylanilino)fluoran, 3-(1-ethyl-2-methylindole-3-yl)-3-(2-ethoxy-4-diethylaminophenyl)-4-azaphthalide, 3-(1-ethyl-2-methylindole-3-yl)-3-(2-ethoxy-4-diethylaminophenyl)-7-azaphthalide, 3-(1-ethyl-2-methylindole-3-yl)-3-(2-methyl-4-diethylaminophenyl)-4-azaphthalide, 3-(1-ethyl-2-methylindole-3-yl)-3-(2-methyl-4-diethylaminophenyl)-7-azaphthalide, 3-(1 -ethyl-2-methylindole-3-yl)-3-(4-diethylaminophenyl)-4-azaphthalide, 3-(1 -ethyl- 2-methylindole-3-yl)-3-(4-N-n-amyl-N-methylaminophenyl)-4-azaphthalide, 3-(1- methyl-2-methylindole-3-yl)-3-(2-hexyloxy-4-diethylaminophenyl)-4-azaphthalide, 3- (1-ethyl-2-methylindole-3-yl)-3-(2-ethoxy-4-diethylaminophenyl)-4-azaphthalide, 3- (N-cyclohexyl-N-methylamino)-6-methyl-7-phenylaminofluoran, 3-(N-ethyl-N- isoamylamino)-6-methyl-7-phenylaminofluoran, 3-(N-ethyl-p-toluidino)-6-methyl-7- phenylaminofluoran, 3,3-bis(2-ethoxy-4-diethylaminphenyl)-4-azaphthalide, 3,3- bis(2-ethoxy-4-diethylaminphenyl)-7-azaphthalide, 3,6-dibutoxyfluoran, 3,6- diethoxyfluoran, 3,6-dimethoxyfluoran, S-bromo-β-cyclohexylaminofluoran, 3- chloro-β-cyclohexylaminofluoran, 3-dibutylamino-7-(o-chloro-phenylamino)fluoran, 3-diethylamino-5-methyl-7-dibenzylaminofluoran, 3-diethylamino-6-(m- trifluoromethylanilino)fluoran, 3-diethylamino-6,7-dimethylfuoran, 3-diethylamino-6- methyl-7-xylidinofluoran, 3-diethylamino-7-(2-carbomethoxy-phenylamino)fluoran, 3-diethylamino-7-(N-acetyl-N-methylamino)fluoran, 3-diethylamino-7-(N- chloroethyl-N-methylamino)fluoran, 3-diethylamino-7-(N-methyl-N- benzylamino)fluoran, 3-diethylamino-7-(o-chlorophenylamino)fluoran, 3- diethylamino-7-chlorofluoran, 3-diethylamino-7-dibenzylaminofluoran, 3- diethylamino-7-diethylaminofluoran, 3-diethylamino-7-N-methylaminofluoran, 3- dimethylamino-6-methoxylfluoran, 3-dimethylamino-7-methoxyfluoran, 3-methyl-6- (N-ethyl-p-toluidino)fluoran, 3-piperidino-6-methyl-7-phenylaminofluoran, 3- pyrrolidino-6-methyl-7-p-butylphenylaminofluoran, and 3-pyrrolidino-6-methyl-7- phenylaminofluoran.

Additional dyes that may be alloyed in embodiments of the dual wavelength system disclosed herein include, but are not limited to leuco dyes such as fluoran leuco dyes and phthalide contrast formers as are described in "The Chemistry and Applications of Leuco Dyes," Muthyala, Ramiah, ed., Plenum Press (1997) (ISBN 0-306-45459-9). Embodiments of the markable coating 230 may include almost any known leuco dye, including, but not limited to, amino-triarylmethanes, aminoxanthenes, aminothioxanthenes, amino-9, 10-dihydro-acridines, aminophenoxazines, aminophenothiazines, aminodihydro-phenazines, aminodiphenylmethanes, aminohydrocinnamic acids (cyanoethanes, leuco methines) and corresponding esters, 2(p-hydroxyphenyl)-4, 5-diphenylimidazoles, indanones, leuco indamines, hydrazines, leuco indigoid dyes, amino-2, 3- dihydroanthraquinones, tetrahalo-p, p'-biphenols, 2(p-hydroxyphenyl)-4, 5- diphenylimidazoles, phenethylanilines, and mixtures thereof.

Particularly suitable leuco dyes include: 2'-anilino-3'-methyl-6'-(dibutylamino)-fluoran:

2-anilino-3-methyl-6-(N-ethyl-N-isoamylamino)fluoran:

2-anilino-3-methyl-6-(di-n-amylamino)fluoran:

All three of the previously listed dyes are commercially available from Nagase Co of Japan. Additional examples of suitable dyes for the dual wavelength system include: Pink DCF (CAS 29199-09-5); Orange-DCF (CAS 21934-68-9); Red-DCF (CAS 26628-47-7); Vermilion-DCF (CAS 117342-26-4); bis(dimethyl)aminobenzoyl phenothiazine (CAS 1249-97-4); Green-DCF (CAS 34372-72-0); chloroanilino dibutylaminofluoran (CAS 82137-81-3); NC-Yellow-3 (CAS 36886-76-7); Copikem37 (CAS 144190-25-0); Copikem3 (CAS 22091-92-5), available from Hodogaya, Japan or Noveon, Cincinnati, USA.

Still other non-limiting examples of suitable fluoran-based leuco dyes for the dual and single wavelength system include: 3-diethylamino-6-methyl-7- anilinofluoran 3-(N-ethyl-p-toluidino)-6-methyl-7-anilinofluoran, 3-(N-ethyl-N- isoamylamino)-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-(o,p- dimethylanilino)fluorane, 3-pyrrolidino-6-methyl-7-anilinofluoran, 3-piperidino-6- methyl-7-anilinofluoran, 3-(N-cyclohexyl-N-methylamino)-6-methyl-7-anilinofluoran, 3-diethylamino-7-(m-trifluoromethylanilino) fluoran, 3-dibutylamino-6-methyl-7- anilinofluoran, 3-diethylamino-6-chloro-7-anilinofluoran, 3-dibutylamino-7-(o- chloroanilino)fluoran, 3-diethylamino-7-(o-chloroanilino)fluoran 3-di-n-pentylamino- 6-methyl-7-anilinofluoran, 3-di-n-butylamino-6-methyl-7-anilinofluoran, 3-(n-ethyl-n- isopentylamino)-6-methyl-7-anilinofluoran, 3-pyrrolidino-6-methyl-7-anilinofluoran, 1 (3H)-isobenzofluranone, 4,5,6,7-tetrachloro-3, 3-bis [2-[4-(dimethylamino)phenyl]- 2-(4-methoxyphenyl)ethenyl] fluoran, and mixtures thereof. Aminotriarylmethane leuco dyes may also be used in embodiments of the present invention such as tris(N,N-dimethylaminophenyl) methane (LCV); tris(N,N-diethylaminophenyl) methane (LECV); tris(N,N-di-n-propylaminophenyl) methane (LPCV); tris(N,N-din- butylaminophenyl) methane (LBCV); bis(4-diethylaminophenyl)-(4-diethylamino-2- methyl-phenyl) methane (LV-1 ); bis(4-diethylamino-2-methylphenyl)-(4- diethylamino-phenyl) methane (LV-2); tris(4-diethylamino-2-methylphenyl) methane (LV-3); bis(4-diethylamino-2-methylphenyl) (3,4-diemethoxyphenyl) methane (LB- 8); aminotriarylmethane leuco dyes having different alkyl substituents bonded to the amino moieties wherein each alkyl group is independently selected from d-C₄ alkyl; and aminotriarylmethane leuco dyes with any of the preceding named structures that are further substituted with one or more alkyl groups on the aryl rings wherein the latter alkyl groups are independently selected from CrC₃ alkyl. Any suitable developer may be used with these leuco dyes. According to certain embodiments, the desired developer is provided in the form of a precursor that can be photochemically or photothermally modified to become the desired developer. As previously mentioned, by providing the developer in precursor form, the need to physically separate the developer from the dye is eliminated. For example, rather than providing one of the color-forming components as particles that are suspended in the matrix, both the dye and the developer precursor can be dissolved in the matrix.

Developer precursors suitable for use in the embodiments of the disclosed herein, without limitation, acetate or benzoate esters of phenolic compounds, such as sulfonyl diphenol, diallyl sulphonyl diphenol, Bisphenol A, curcumin, alpha- naphthol, beta-naphthol, or any other compounds with an OH group attached to an aromatic ring.

Other suitable developer precursors involving photochemical reactions are phenyl esters that undergo a molecular rearrangement so as to become phenolic compounds capable of developing (activating) the leuco dye. Such rearrangements are sometimes referred to as Fries rearrangements. It is to be understood that Fries rearrangements may be thermally driven. In some instances, esters may undergo photo-initiated Fries rearrangements (sometimes referred to as Photo Fries rearrangements). Both types of rearrangement (thermal- and photo-driven) are within the scope of the disclosed embodiments, and that the stimulus for such rearrangements may be light, heat, or a combination thereof.

In certain embodiments, suitable developer precursors include compounds having the formula:

ROCOR^', where R is an aryl group and R^' is an alkyl or aryl group. Exemplary compounds include, but are not limited to, di-O-acetylated and di-O-benzoylated curcuminoids. Alternatively, any aryl ester that absorbs or has a peak absorption wavelength ranging from about 380 nm to about 420 nm, and more particularly from about 400 nm to about 410 nm may be a developer precursor suitable for use herein. These developer precursors are suitable absorbers 239 for the leuco dyes.

Other suitable ester precursors of developers include bisphenol-A, bisphenol-S, hydroxy benzyl benzoates, TG-SA (phenol, 4,4'-sulfonylbis[2-(2- propenyl)]) and poly-phenols. An example of a contrast agent 240 that experiences absorption coefficient changes, refractive index changes, reflectivity changes, dimension (e.g., thickness) changes, and/or distortion includes silicon naphthalocyanine (SiNc) (CAS 92396- 88-8) available from Aldrich (which, when including thhexyloxy substituents, has sufficient solubility in UV lacquer or other solvents of the markable coatings 230). Other examples of such contrast agents 240 include PRO-JET™ 800NP, PRO- JET™ 830NP, PRO-JET™ 900NP, all of which are commercially available from Fujifilm as imaging colorants for inkjet applications.

It has been found that absorbers that have modifying groups as described in US Patent No. 6,015,896 and US Patent No. 6,025,486 (both of which are incorporated herein by reference) are suitable for use as contrast agents 240 in the embodiments of the dual or single wavelength system disclosed herein. Such modifying groups may be present on the ring, the atom or the ion at the center of a naphthalocyanine or a phthalocyanine complex. Examples of some suitable naphthalocyanine and phthalocyanine dyes are shown below:

Still further, it has been unexpectedly found that some commercial dyes previously used for recording of low density optical media at 650 nm and 780 nm are useful as contrast agents 240 in the high density optical media. Such dyes may be particular useful in combination with absorbers 239 such as C.I. Solvent Yellow 93 or C.I. Solvent Yellow 163. Examples of such commercial dyes include those used in conventional DVD or CD recording, such as IRGAPHOR® Ultragreen MX, IRGAPHOR® LASERVIOLET, IRGAPHOR® 1699 (all of which are commercially available from Ciba, Tarrytown, NY).

Additional examples of suitable contrast agents 240 for both the single and dual wavelength systems include the following: 1 ) those described in U.S. Patent No. 5,079,135, Japanese Patent 2,910,042 B2, European Patent 0376327 B1 , and Hong Kong Patent 1007621 A1 , all of which are assigned to Sony Corporation, Tokyo, and incorporated herein by reference; and 2) those described in U.S. Patent Application Publication No. 2002/0015858 and Japanese Patent Application Publication 2002-002112, both of which are assigned to Toyo Ink Mfg. Co. Ltd., Tokyo, and incorporated herein by reference.

In a non-limiting example of the dual wavelength recording medium 100 disclosed herein, the markable coating 230 may include a combination of the leuco dye Noveon Specialty Cyan 39 as the contrast agent 240 and C.I. Solvent Yellow 93 as the absorber 239. Such a markable coating 230 may also include suitable developers, such as zinc salicylate, and PERGAFAST® 201 (commercially available form Ciba). As previously mentioned, another non-limiting example of the dual wavelength markable coating 230 includes C.I. Solvent Yellow 93 as the absorber 239 and IRGAPHOR® 1699 as the contrast agent 240.

In a non-limiting example of the single wavelength recording medium 100 disclosed herein, the markable coating 230 may include a combination of an absorber 239 selected from those listed hereinabove, and a contrast agent 240 selected from phthalocyanine dyes. The ratio and choice of the components is configured so as to enable writing and reading at the 405 nm waveband. As a non- limiting example, a solution of cyanine absorber S0512 (available from Few Chemicals Gmbh, Germany) as the absorber 239 and IRGAPHOR® Ultragreen MX as the contrast agent 240 in a ratio 1 :9 may be used to form media 100 that write at 405 nm waveband, and read at 405 nm waveband.

Radiation sources (e.g., a laser or LED) that emit light having blue and indigo wavelengths ranging from about 375 nm to about 435 nm can be used to develop the present color- or contrast-forming compositions. Therefore, color- or contrast-forming compositions may be selected for use in devices that emit wavelengths within this range. In particular, radiation sources such as the lasers used in certain DVD and laser disk recording equipment emit energy at a wavelength of about 405 nm. An additional radiation absorber tuned to the selected wavelength may be included so as to enhance localized heating. In the embodiments disclosed herein, the matrix material can be any composition suitable for dissolving and/or dispersing the absorber 239 and the contrast agent 240. Acceptable matrix materials include, but are not limited to, UV- curable matrices such as acrylate derivatives, oligomers and monomers, with or without a photo package. A photo package may include a light-absorbing species which initiates reactions for curing the matrix, such as, for example, benzophenone derivatives. Other examples of photoinitiators for free radical polymerization monomers and pre-polymers include, but are not limited to, thioxanethone derivatives, anthraquinone derivatives, acetophenones and benzoin ether types. It may be desirable to choose a matrix that can be cured by a form of radiation other than the type of radiation that is used for writing.

Matrices based on cationic polymerization resins may require photo- initiators based on aromatic diazonium salts, aromatic halonium salts, aromatic sulfonium salts and metallocene compounds. An example of an acceptable matrix includes Nor-Cote CLCDG-1250A or Nor-Cote CDGOOO (mixtures of UV curable acrylate monomers and oligomers), which contains a photoinitiator (hydroxy ketone) and organic solvent acrylates (e.g., methyl methacrylate, hexyl methacrylate, beta-phenoxy ethyl acrylate, and hexamethylene acrylate). Other acceptable matrixes include acrylated polyester oligomers such as CN292, CN293, CN294, SR351 (trimethylolpropane tri acrylate), SR395 (isodecyl acrylate), and SR256 (2(2-ethoxyethoxy) ethyl acrylate) available from Sartomer Co.

In some instances, the photochemical and/or photothermal mechanisms that cause the developer precursors to become developers are much slower when the solid matrix is below its glass transition temperature. Without subscribing to a particular theory, the photochemical reactions in solids have an added energy barrier to heat the matrix above its glass transition temperature (T₉). Thus, in some embodiments, it is preferred to provide sufficient photothermal energy in the region of the desired mark 242 to locally heat the matrix above its glass transition temperature T₉. T₉ typically depends on the polymer composition of the matrix, and may be selected, if desired, by selecting the polymer that is used for the matrix. In some embodiments, T₉ will range from about 120°C to about 250°C.

The imaging compositions formed in the manner described herein can be applied to the surface of a disc, such as a CD, DVD, HD-DVD, BLU-RAY disc, or the like. A non-limiting example of the imaging medium 100 disclosed herein may be referred to as "Write Blue-Read Red" discs, which record data at the 405 nm band, and data recorded thereon is read at the 650 nm band. Further, discs may be used in systems disclosed herein that include optical recording and/or reading capabilities. Such systems typically include a laser emitting light (e.g., light source 150) having a predetermined wavelength and power. Systems that include optical reading capability further include an optical pickup unit 157 coupled to the laser. Lasers and optical pickup units are known in the art. Referring again specifically to Figures 1 and 2, an exemplary read/write system 170 includes the processor 166, one or more lasers 150 (suitable for emitting write and/or read wavelengths), and the optical pickup 157. Signals 163 from processor 166 cause laser 150 to emit light at the desired power level. Light reflected 165 from the imaging medium 100 surface is detected by pickup 157, which in turn sends a corresponding signal 165 back to processor 166.

When it is desired to record, the imaging medium 100 is positioned such that light (having a wavelength ranging from 375 nm to 435 nm) emitted by laser 150 is incident on the marking layer 230. The laser 150 is operated such that the light incident on the marking layer 230 transfers sufficient energy to the surface to cause a mark 242. Both the laser 150 and the position of the imaging medium 100 are controlled by the processor 166, such that light is emitted by the laser 150 in pulses that form a pattern of marks 242 on the surface of the imaging medium 100. The pattern of marks 242 formed will be readable at the write wavelength (e.g., 405 nm) or at a wavelength 200 nm from the write wavelength, depending, at least in part, on the materials and concentrations selected for the absorber 239 and contrast agent 240.

When it is desired to read a pattern of marks 242 on the surface of an imaging medium 100, the imaging medium 100 is again positioned such that light (in some embodiments, having a wavelength that ranges from 620 nm to 680 nm, and in other embodiments, having a wavelength that ranges from 375 nm to 435 nm) emitted by laser 150 is incident on the marked surface. The laser 150 is operated such that the light incident at the surface does not transfer sufficient energy to the surface to cause a mark 242. Instead, the incident light is reflected from the marked surface to a greater or lesser degree, depending on the absence or presence of a mark 242. As the imaging medium 100 moves, changes in reflectance are recorded by optical pickup 157 which generates a signal 165 corresponding to the marked surface. Both the laser 150 and the position of the imaging medium 100 are controlled by the processor 166 during the reading process.

It is be understood that the read/write system 170 described herein is merely exemplary and includes components that are understood in the art. Various modifications can be made, including the use of multiple lasers, processors, and/or pickups and the use of light having different wavelengths. The read components may be separated from the write components, or may be combined in a single device.

To further illustrate embodiment(s) of the present disclosure, an example is given herein. It is to be understood that this example is provided for illustrative purposes and is not to be construed as limiting the scope of the disclosed embodiment(s).

EXAMPLE - DUAL WAVELENGTH SYSTEM Figures 3-5 illustrate that notion that when a DVDR dye (i.e., a conventional red absorbing dye) is used as a contrast agent 240 in the dual wavelength system disclosed herein, certain advantages over conventional Write Red - Read Red media. The recording blue laser spot diameter is significantly smaller than the red spot in conventional DVDR drives. Such a diameter difference increases the focused intensity of the laser energy in the dye layer during recording. As a result, relatively lower laser power is needed to record data using 405 nm laser compared to 658 nm laser (see Figures 3 and 4), cross talk (track to track) of recorded data may be reduced, and contrast (modulation) of data recorded with 405 nm blue laser is significantly greater than data recorded with 658 nm red laser (see Figure 3). Furthermore, the read stability of data recorded with a Blue 405 nm laser is significantly superior to that of data recorded with standard Red 658 nm laser (see Figure 5).

It is believed that Media-on-Demand (MOD) may benefit from the dual wavelength systems disclosed herein. It is desirable to deliver media content over the Internet using secure, copy protected methods. Of particular interest for MOD applications are discs that appear as close as possible to DVD-ROM after recording. In particular, low Push-Pull and Wobble signals (at 650 nm) are desired for good playback compatibility with legacy devices. Blue laser recording improves performance margins compared to standard DVDR media (as shown in the

Figures), and as such enables the manipulation of groove and coating structures to tune discs specifically for MOD application requirements. For example, it is possible to significantly reduce the Push-pull and Wobble amplitude of the dual wavelength media while retaining specification for other key parameters such as reflectivity, modulation and jitter (as shown in Figures 3-5). It is believed that Blue laser writing of the dual wavelength media in DVD-ROM format provides an excellent option for the MOD application as the disc structure coupled with hard encryption coding will allow only Blue-Laser writing, yet excellent compatibility for DVD reading. By encrypting a hard key in the dual wavelength media, the content providers can substantially assure security and copy protection, without the opportunity for incompatibility.

Two compositions were formulated and were spin coated on optical disc substrates. One of the compositions included 1.5% of a conventional dye (IRGAPHOR® 1699) that is absorbing in the red wavelength, and the other composition included 1.5% of a combination of the red-wavelength absorbing conventional dye (IRGAPHOR® 1699) and an absorber (C.I. Solvent Yellow 93, making up 10% of the combination) that is highly absorbing at the blue wavelength. The discs were exposed to a focused blue ray laser at 405 nm, operating at 1OmW and 8.4ms^"1 (2.4x DVD) speed. The data was recorded on the discs using conventional DVD write strategies. As shown in Figure 6, the composition including the absorber exhibited a much greater absorbance at 405 nm than the composition without the absorber.

While several embodiments have been described in detail, it will be apparent to those skilled in the art that the disclosed embodiments may be modified. Therefore, the foregoing description is to be considered exemplary rather than limiting.

Claims

What is claimed is:

1. An optical data recording medium (100), comprising: a substrate (220); and a markable coating (230) established on the substrate (220), the coating (230) including an absorber (239) configured to absorb light of a first wavelength, and a contrast agent (240) configured to undergo a chemical or physical change upon receiving energy from the absorber (239), thereby at least one of 1 ) producing an optically detectable mark (242) that generates a pattern that is readable with light of a second wavelength that is at least 200 nm apart from the first wavelength or 2) producing an optically detectable mark (242) that generates a pattern that is readable with light of the first wavelength.

2. The optical data recording medium (100) as defined in claim 1 wherein the contrast agent (240) is configured to produce the optically detectable mark (242) that generates the pattern that is readable with light of the second wavelength, wherein the absorber (239) is selected from curcumin; crocetin; porphyrin and derivatives thereof; azo dyes; C.I. Solvent Yellow 93; C.I. Solvent Yellow 163; 1 -(2-chloro-5-sulfophenyl)-3-methyl-4-(4~sulfophenyl)azo-2-pyrazolin- 5-one disodium salt; ethyl 7-diethylaminocoumarin-3-carboxylate; 3,3'- diethylthiacyanine ethylsulfate; 3-allyl-5-(3-ethyl-4-methyl-2-thiazolinylidene) rhodanine; tris(8-hydroxyquinolinato)aluminum; tris(5-cholor-8- hydroxyquinolinato)aluminum; 2-(4-(1-methyl-ethyl)-phenyl)-6-phenyl-4H-thiopyran- 4-ylidene)-propanedinitril-1 ,1-dioxide; 4,4'-[1 ,4-phenylenebis(1 ,3,4-oxadiazole-5,2- diyl)]bis N,N-diphenyl benzeneamine; bis-tetraethylammonium-bis(1 ,2-dicyano- dithiolto)-zinc(ll); 2-(4,5-dihydronaphtho[1 ,2-d]-1 ,3-dithiol-2-ylidene)-4,5-dihydro- naphtho[1 ,2-d]1 ,3-dithiole; 1 ,3-dimethyl-5-[2-(1 -methyl-pyrrolidin-2-ylidene)- ethylidene]-pyrimidine-2,4,6-thone; and 1 ,3-dimethyl-5-[2-(3-methyl-oxazolidin-2- ylidene)-ethylidene]-pyrimidine-2,4,6-trione; and wherein the contrast agent (240) is selected from leuco dyes, naphthalocyanine dyes, phthalocyanine dyes, diazo dyes, porphyrin dyes, metal complex dyes, anthraquinone dyes, quinazarin dyes and polyene dyes.

3. The optical data recording medium (100) as defined in any of claims 1 through 2 wherein the absorber (239) has a peak absorption at a 405 nm band, and wherein the optically detectable mark (242) is readable at a 650 nm band or at a 780 nm band.

4. The optical data recording medium (100) as defined in claim 1 wherein the contrast agent (240) is configured to produce the optically detectable mark

(242) that generates the pattern that is readable with light of the first wavelength, wherein the absorber (239) is selected from curcumin; crocetin; porphyrin and derivatives thereof; azo dyes; C.I. Solvent Yellow 93; C.I. Solvent Yellow 163; 1-(2- chloro-5-sulfophenyl)-3-methyl-4-(4~sulfophenyl)azo-2-pyrazolin-5-one disodium salt; ethyl 7-diethylaminocoumarin-3-carboxylate; 3,3'-diethylthiacyanine ethylsulfate; 3-allyl-5-(3-ethyl-4-methyl-2-thiazolinylidene) rhodanine; ths(8- hydroxyquinolinato)aluminum; tris(5-cholor-8-hydroxyquinolinato)aluminum; 2-(4- (1 -methyl-ethyl)-phenyl)-6-phenyl-4H-thiopyran-4-ylidene)-propanedinithl-1 , 1 - dioxide; 4,4'-[1 ,4-phenylenebis(1 ,3,4-oxadiazole-5,2-diyl)]bis N,N-diphenyl benzeneamine; bis-tetraethylammonium-bis(1 ,2-dicyano-dithiolto)-zinc(ll); and 2- (4,5-dihydronaphtho[1 ,2-d]-1 ,3-dithiol-2-ylidene)-4,5-dihydro-naphtho[1 ,2-d]1 ,3- dithiole; 1 ,3-dimethyl-5-[2-(1 -methyl-pyrrolidin-2-ylidene)-ethylidene]-pyrimidine- 2,4,6-trione; and 1 ,3-dimethyl-5-[2-(3-methyl-oxazolidin-2-ylidene)-ethylidene]- pyrimidine-2,4,6-trione; and wherein the contrast agent (240) is a phthalocyanine dye.

5. A method for at least one of i) optically recording data or visual images, or ii) reading optically recorded data or visual images, the method comprising: providing an optical data recording medium (100) including: a substrate (220); and a markable coating (230) established on the substrate (220), the markable coating (230) including an absorber (239) configured to absorb light of a first wavelength, and a contrast agent (240) configured to undergo a chemical or physical change upon receiving energy from the absorber

(239), thereby at least one of 1 ) producing an optically detectable mark (242) that generates a pattern that is readable with light of a second wavelength that is at least 200 nm apart from the first wavelength or 2) producing an optically detectable mark (242) that generates a pattern that is readable with light of the first wavelength; and beaming i) light of the first wavelength from a light source (150) so as to cause the absorber (239) to capture energy and transfer the energy to the contrast agent (240) to form the optically detectable mark (242) that generates the pattern that is readable with light of the second wavelength or to form the optically detectable mark (242) that generates the pattern that is readable with light of the first wavelength; ii) light of the second wavelength from a light source (150) so as to cause a previously formed optically detectable mark (242) on the markable coating (230) to generate the pattern that is readable with light of the second wavelength; or iii) light of the first wavelength from a light source (150) so as to cause a previously formed optically detectable mark (242) on the markable coating (230) to generate the pattern that is readable with light of the first wavelength.

6. The method as defined in claim 5 wherein providing the optical data recording medium (100) includes: forming the markable coating (230) by: selecting materials for the absorber (239) and contrast agent (240) that enable writing at the first wavelength, wherein the first wavelength is 405 nm, and reading at the second wavelength selected from 650 nm or 780 nm; and combining the selected materials in a matrix in a ratio of absorber (239) to contrast agent (240) that enables writing at the first wavelength, and reading at the second wavelength; and establishing the markable coating (230) on the substrate (220).

7. The method as defined in any of claims 5 or 6 wherein the contrast agent (240) is configured to produce the optically detectable mark (242) that generates the pattern that is readable with light of the second wavelength, wherein the absorber (239) is selected from curcumin; crocetin; porphyrin and derivatives thereof; azo dyes; C.I. Solvent Yellow 93; C.I. Solvent Yellow 163; 1-(2-chloro-5- sulfophenyl)-3-methyl-4-(4~sulfophenyl)azo-2-pyrazolin-5-one disodium salt; ethyl 7-diethylaminocoumarin-3-carboxylate; 3,3'-diethylthiacyanine ethylsulfate; 3-allyl- 5-(3-ethyl-4-methyl-2-thiazolinylidene) rhodanine; tris(8- hydroxyquinolinato)aluminum; tris(5-cholor-8-hydroxyquinolinato)aluminum; 2-(4- (1 -methyl-ethyl)-phenyl)-6-phenyl-4H-thiopyran-4-ylidene)-propanedinithl-1 , 1 - dioxide; 4,4'-[1 ,4-phenylenebis(1 ,3,4-oxadiazole-5,2-diyl)]bis N,N-diphenyl benzeneamine; bis-tetraethylammonium-bis(1 ,2-dicyano-dithiolto)-zinc(ll); 2-(4,5- dihydronaphtho[1 ,2-d]-1 ,3-dithiol-2-ylidene)-4,5-dihydro-naphtho[1 ,2-d]1 ,3-dithiole; 1 ,3-dimethyl-5-[2-(1-methyl-pyrrolidin-2-ylidene)-ethylidene]-pyrimidine-2,4,6-thone; and 1 ,3-dimethyl-5-[2-(3-methyl-oxazolidin-2-ylidene)-ethylidene]-pyrimidine-2,4,6- trione; and wherein the contrast agent (240) is selected from leuco dyes, naphthalocyanine dyes, phthalocyanine dyes, diazo dyes, porphyrin dyes, metal complex dyes, anthraquinone dyes, quinazahn dyes and polyene dyes.

8. The method as defined in claim 5 wherein providing the optical data recording medium (100) includes: forming the markable coating (230) by: selecting materials for the absorber (239) and contrast agent (240) that enables writing and reading at the first wavelength, wherein the first wavelength is 405 nm; and combining the selected materials in a matrix in a ratio of absorber (239) to contrast agent (240) that enables writing and reading at the first wavelength; and establishing the markable coating (230) on the substrate (220).

9. The method as defined in any of claims 5 or 8 wherein the contrast agent (240) is configured to produce the optically detectable mark (242) that generates the pattern that is readable with light of the first wavelength, wherein the absorber (239) is selected from curcumin; crocetin; porphyrin and derivatives thereof; azo dyes; C.I. Solvent Yellow 93; C.I. Solvent Yellow 163; 1-(2-chloro-5-sulfophenyl)-3- methyl-4-(4~sulfophenyl)azo-2-pyrazolin-5-one disodium salt; ethyl 7- diethylaminocoumahn-3-carboxylate; 3,3'-diethylthiacyanine ethylsulfate; 3-allyl-5- (3-ethyl-4-methyl-2-thiazolinylidene) rhodanine; tris(8- hydroxyquinolinato)aluminum; tris(5-cholor-8-hydroxyquinolinato)aluminum; 2-(4- (1 -methyl-ethyl)-phenyl)-6-phenyl-4H-thiopyran-4-ylidene)-propanedinithl-1 , 1 - dioxide; 4,4'-[1 ,4-phenylenebis(1 ,3,4-oxadiazole-5,2-diyl)]bis N,N-diphenyl benzeneamine; bis-tetraethylammonium-bis(1 ,2-dicyano-dithiolto)-zinc(ll); 2-(4,5- dihydronaphtho[1 ,2-d]-1 ,3-dithiol-2-ylidene)-4,5-dihydro-naphtho[1 ,2-d]1 ,3-dithiole; 1 ,3-dimethyl-5-[2-(1-methyl-pyrrolidin-2-ylidene)-ethylidene]-pyrimidine-2,4,6-thone; and 1 ,3-dimethyl-5-[2-(3-methyl-oxazolidin-2-ylidene)-ethylidene]-pyrimidine-2,4,6- trione; and wherein the contrast agent (240) is a phthalocyanine dye.

10. A system (170) for at least one of recording or transmitting optical data or visual images, comprising: an optical data or visual image recording medium (100) including: a substrate (220); and a markable coating (230) established on the substrate (220), the markable coating (230) including an absorber (239) configured to absorb light of a first wavelength, and a contrast agent (240) configured to undergo a chemical or physical change upon receiving energy from the absorber (239), thereby at least one of 1 ) producing an optically detectable mark

(242) that generates a pattern that is readable with light of a second wavelength that is at least 200 nm apart from the first wavelength or 2) producing an optically detectable mark (242) that generates a pattern that is readable with light of the first wavelength; and a recording and transmitting device including a light source (150) positioned to illuminate the recording medium (100) i) with light of the first wavelength, thereby causing the absorber (239) to capture energy and transfer the energy to the contrast agent (240) to form the optically detectable mark (242) that generates the pattern that is readable with light of the second wavelength or to form the optically detectable mark (242) that generates the pattern that is readable with light of the first wavelength; ii) with light of the second wavelength, thereby causing a previously formed optically detectable mark (242) on the markable coating (230) to generate the pattern that is readable with light of the second wavelength; or iii) with light of the first wavelength, thereby causing a previously formed optically detectable mark (242) on the markable coating (230) to generate the pattern that is readable with light of the first wavelength.

11. The system (170) as defined in claim 10 wherein for optically transmitting data and visual images, the system (170) further comprises: a sensor (157) positioned to detect the pattern that is readable with light of the second wavelength or the pattern that is readable with light of the first wavelength as the medium (100) moves in relation to the sensor (157); a processor (166) operatively connected to the sensor (157) such that the processor (166) receives, from the sensor (157), at least one signal based on the detected pattern; an analyzer (168) operatively connected to the processor (166) such that the analyzer (168) receives the at least one signal from the processor (166), the analyzer (168) configured to analyze the at least one signal and generate data therefrom; and a computer data base configured to receive and store the data from the analyzer (168), wherein the is accessible via the computer data base.

12. The system (170) as defined in any of claims 10 or 11 wherein the contrast agent (240) is configured to produce the optically detectable mark (242) that generates the pattern that is readable with light of the second wavelength, wherein the absorber (239) is selected from curcumin; crocetin; porphyrin and derivatives thereof; azo dyes; C.I. Solvent Yellow 93; C.I. Solvent Yellow 163; 1-(2- chloro-5-sulfophenyl)-3-methyl-4-(4~sulfophenyl)azo-2-pyrazolin-5-one disodium salt; ethyl 7-diethylaminocoumarin-3-carboxylate; 3,3'-diethylthiacyanine ethylsulfate; 3-allyl-5-(3-ethyl-4-methyl-2-thiazolinylidene) rhodanine; tris(8- hydroxyquinolinato)aluminum; tris(5-cholor-8-hydroxyquinolinato)aluminum; 2-(4- (1 -methyl-ethyl)-phenyl)-6-phenyl-4H-thiopyran-4-ylidene)-propanedinithl-1 , 1 - dioxide; 4,4'-[1 ,4-phenylenebis(1 ,3,4-oxadiazole-5,2-diyl)]bis N,N-diphenyl benzeneamine; bis-tetraethylammonium-bis(1 ,2-dicyano-dithiolto)-zinc(ll); 2-(4,5- dihydronaphtho[1 ,2-d]-1 ,3-dithiol-2-ylidene)-4,5-dihydro-naphtho[1 ,2-d]1 ,3-dithiole; 1 ,3-dimethyl-5-[2-(1-methyl-pyrrolidin-2-ylidene)-ethylidene]-pyrimidine-2,4,6-thone; and 1 ,3-dimethyl-5-[2-(3-methyl-oxazolidin-2-ylidene)-ethylidene]-pyrimidine-2,4,6- trione and wherein the contrast agent (240) is selected from leuco dyes, naphthalocyanine dyes, phthalocyanine dyes, diazo dyes, porphyrin dyes, metal complex dyes, anthraquinone dyes, quinazahn dyes and polyene dyes.

13. The system as defined in claim 12 wherein materials selected for the absorber (239) and the contrast agent (240), and a ratio of the selected absorber (239) to the selected contrast agent (240) enable writing at the first wavelength, wherein the first wavelength is 405 nm, and enable reading at the second wavelength selected from 650 nm or 780 nm.

14. The system (170) as defined in any of claims 10 or 11 wherein the contrast agent (240) is configured to produce the optically detectable mark (242) that generates the pattern that is readable with light of the first wavelength, wherein the absorber (239) is selected from curcumin; crocetin; porphyrin and derivatives thereof; azo dyes; C.I. Solvent Yellow 93; C.I. Solvent Yellow 163; 1-(2-chloro-5- sulfophenyl)-3-methyl-4-(4~sulfophenyl)azo-2-pyrazolin-5-one disodium salt; ethyl 7-diethylaminocoumarin-3-carboxylate; 3,3'-diethylthiacyanine ethylsulfate; 3-allyl- 5-(3-ethyl-4-methyl-2-thiazolinylidene) rhodanine; tris(8- hydroxyquinolinato)aluminum; tris(5-cholor-8-hydroxyquinolinato)aluminum; 2-(4- (1 -methyl-ethyl)-phenyl)-6-phenyl-4H-thiopyran-4-ylidene)-propanedinithl-1 , 1 - dioxide; 4,4'-[1 ,4-phenylenebis(1 ,3,4-oxadiazole-5,2-diyl)]bis N,N-diphenyl benzeneamine; bis-tetraethylammonium-bis(1 ,2-dicyano-dithiolto)-zinc(ll); and 2- (4,5-dihydronaphtho[1 ,2-d]-1 ,3-dithiol-2-ylidene)-4,5-dihydro-naphtho[1 ,2-d]1 ,3- dithiole; 1 ,3-dimethyl-5-[2-(1 -methyl-pyrrolidin-2-ylidene)-ethylidene]-pyrimidine- 2,4,6-trione; and 1 ,3-dimethyl-5-[2-(3-methyl-oxazolidin-2-ylidene)-ethylidene]- pyrimidine-2,4,6-trione; and wherein the contrast agent (240) is a phthalocyanine dye.

15. The system (170) as defined in claim 14 wherein materials selected for the absorber (239) and the contrast agent (240), and a ratio of the selected absorber (239) to the selected contrast agent (240) enable writing and reading at the first wavelength, wherein the first wavelength is 405 nm.

16. A method of making an optical data medium (100) for at least one of i) optically recording data or visual images, or ii) reading optically recorded data or visual images, comprising: forming a markable coating (230) by mixing an absorber (239) configured to absorb light of a first wavelength and a contrast agent (240) configured to undergo a chemical or physical change upon receiving energy from the absorber (239) and to 1 ) produce an optically detectable mark (242) that generates a pattern that is readable with light of a second wavelength that is at least 200 nm apart from the first wavelength or 2) produce an optically detectable mark (242) that generates a pattern that is readable with light of the first wavelength; and establishing the markable coating (230) on a substrate (220).

17. The method as defined in claim 16, further comprising exposing the markable coating (230) to light of the first wavelength, thereby forming the optically detectable mark (242) that generates the pattern that is readable with light of the second wavelength, or the optically detectable mark (242) that that generates the pattern that is readable with light of the first wavelength.

18. The method as defined in claim 17 wherein the markable coating includes i) materials selected for the absorber (239) and the contrast agent (240) and ii) a ratio of the selected absorber (239) to the selected contrast agent (240) that enable writing at the first wavelength, wherein the first wavelength is 405 nm, and enable reading of the pattern at the second wavelength selected from 650 nm or 780 nm, wherein the absorber (239) is selected from curcumin; crocetin; porphyrin and derivatives thereof; azo dyes; C.I. Solvent Yellow 93; C.I. Solvent Yellow 163; 1 -(2-chloro-5-sulfophenyl)-3-methyl-4-(4~sulfophenyl)azo-2-pyrazolin- 5-one disodium salt; ethyl 7-diethylaminocoumarin-3-carboxylate; 3,3'- diethylthiacyanine ethylsulfate; 3-allyl-5-(3-ethyl-4-methyl-2-thiazolinylidene) rhodanine; tris(8-hydroxyquinolinato)aluminum; tris(5-cholor-8- hydroxyquinolinato)aluminum; 2-(4-(1-methyl-ethyl)-phenyl)-6-phenyl-4H-thiopyran- 4-ylidene)-propanedinitril— 1 , 1 -dioxide; 4,4'-[1 ,4-phenylenebis(1 ,3,4-oxadiazole- 5,2-diyl)]bis N,N-diphenyl benzeneamine; bis-tetraethylammonium-bis(1 ,2-dicyano- dithiolto)-zinc(ll); 2-(4,5-dihydronaphtho[1 ,2-d]-1 ,3-dithiol-2-ylidene)-4,5-dihydro- naphtho[1 ,2-d]1 ,3-dithiole; 1 ,3-dimethyl-5-[2-(1 -methyl-pyrrolidin-2-ylidene)- ethylidene]-pyrimidine-2,4,6-trione; and 1 ,3-dimethyl-5-[2-(3-methyl-oxazolidin-2- ylidene)-ethylidene]-pyrimidine-2,4,6-trione; and wherein the contrast agent (240) is selected from leuco dyes, naphthalocyanine dyes, phthalocyanine dyes, diazo dyes, porphyrin dyes, metal complex dyes, anthraquinone dyes, quinazahn dyes and polyene dyes.

19. The method as defined in claim 18, further comprising exposing the optically detectable mark (242) to light of the 650 nm or 780 nm wavelength.

20. The method as defined in claim 16 wherein the markable coating includes i) materials selected for the absorber (239) and the contrast agent (240) and ii) a ratio of the absorber (239) to the contrast agent (240) that enable writing and reading at the first wavelength, wherein the first wavelength is 405 nm, wherein the absorber (239) is selected from curcumin; crocetin; porphyrin and derivatives thereof; azo dyes; C.I. Solvent Yellow 93; C.I. Solvent Yellow 163; 1-(2- chloro-5-sulfophenyl)-3-methyl-4-(4~sulfophenyl)azo-2-pyrazolin-5-one disodium salt; ethyl 7-diethylaminocoumarin-3-carboxylate; 3,3'-diethylthiacyanine ethylsulfate; 3-allyl-5-(3-ethyl-4-methyl-2-thiazolinylidene) rhodanine; tris(8- hydroxyquinolinato)aluminum; tris(5-cholor-8-hydroxyquinolinato)aluminum; 2-(4- (1 -methyl-ethyl)-phenyl)-6-phenyl-4H-thiopyran-4-ylidene)-propanedinithl-1 , 1 - dioxide; 4,4'-[1 ,4-phenylenebis(1 ,3,4-oxadiazole-5,2-diyl)]bis N,N-diphenyl benzeneamine; bis-tetraethylammonium-bis(1 ,2-dicyano-dithiolto)-zinc(ll); 2-(4,5- dihydronaphtho[1 ,2-d]-1 ,3-dithiol-2-ylidene)-4,5-dihydro-naphtho[1 ,2-d]1 ,3-dithiole; 1 ,3-dimethyl-5-[2-(1-methyl-pyrrolidin-2-ylidene)-ethylidene]-pyrimidine-2,4,6-thone; and 1 ,3-dimethyl-5-[2-(3-methyl-oxazolidin-2-ylidene)-ethylidene]-pyrimidine-2,4,6- trione and wherein the contrast agent (240) is a phthalocyanine dye.

21. The method as defined in claim 23, further comprising exposing the optically detectable mark (242) to light of the 405 nm wavelength.

22. A markable coating (230), comprising: a matrix; an absorber (239) selected from curcumin, crocetin, porphyrin, porphyrin derivatives, azo dyes, 4-phenylazoaniline, Alcian Yellow, C.I. Solvent Yellow 93, C.I. Solvent Yellow 163, ethyl 7-diethylaminocoumahn-3-carboxylate, 3,3'- diethylthiacyanine ethylsulfate, and 3-allyl-5-(3-ethyl-4-methyl-2- thiazolinylidene)rhodanine; and a contrast agent (240) selected from phthalocyanine dyes.

23. The markable coating (230) as defined in claim 22 wherein the markable coating is used in a dual wavelength optical recording medium, and wherein the absorber (239) and contrast agent (240) are selected and are present in a ratio such that 1 ) for writing optically detectable marks (242) thereon using light of a 405 nm wavelength, and 2) for reading optically detectable marks (242) formed thereon using light of a 650 nm or 780 nm wavelength.

24. The markable coating (230) as defined in claim 22 wherein the markable coating is used in a single wavelength optical recording medium, and wherein the absorber (239) and contrast agent (240) are selected and are present in a ratio such that 1 ) for writing optically detectable marks (242) thereon using light of a 405 nm wavelength, and 2) for reading optically detectable marks (242) formed thereon using light of the 405 nm wavelength.