JP4009114B2 - Laser optical device - Google Patents

Description

[0001]
[Industrial application fields]
The present invention can be used for a laser marker, a laser trimmer, a laser display, or the like, a laser device using an acousto-optic element (hereinafter referred to as AOM) as a beam intensity modulation means, or a beam obtained by adding a beam scanning mechanism to the device. The present invention relates to a scanning device. More specifically, the present invention relates to a technique for clearly separating a desired modulated beam diffracted by an AOM and other unnecessary diffracted beams and extracting only the desired modulated beam.
[0002]
[Prior art]
It is known that a laser apparatus having various functions can be configured by modulating a laser beam by AOM. AOM can modulate the intensity of an incident beam and is used in a wide variety of laser devices such as laser markers, laser trimmers, and laser displays.
The laser intensity modulation method includes a direct modulation method, and the direct modulation method is often used in a low-power semiconductor laser.
However, as the laser output increases, the duty ratio decreases in the direct modulation method. On the other hand, AOM can ensure a duty ratio even when the laser beam power is large, and is therefore an effective modulation means in a laser apparatus using a watt class high power laser.
[0003]
There are two diffracted beams emitted from the AOM: zero-order light and first-order light. Depending on the incident conditions of the beam, -1st-order and + 2nd-order diffracted light may be emitted simultaneously. Of these, only the first-order diffracted light is normally used as modulated light. This will be referred to as the desired modulated beam. Since other beams are unnecessary, they are called unnecessary diffraction beams. Unnecessary diffraction beams need to be shielded.
However, the diffraction separation angle of the diffracted beam radiated from the AOM is as small as several milliradians. For this reason, it is difficult to shield only unnecessary diffraction beams in the vicinity of the AOM, and when a light other than a desired modulated beam is shielded by a light shielding plate having an aperture, the beam diameter and the aperture diameter become substantially the same. Then, the beam is diffracted at the edge of the opening. Further, if the position of the opening is shifted, the amount of transmitted light is reduced, and the light use efficiency is reduced.
[0004]
A technique described in Japanese Patent Laid-Open No. 9-5589 is known as a technique for cutting off an unnecessary diffracted beam and extracting only a desired modulated beam. In this technique, a plurality of diffracted beams emitted from the AOM with a slight separation angle are guided to a beam expander composed of two groups of convex lenses, and a light shielding plate with a pinhole is placed on the focal plane of the front group. Only the desired modulated beam is allowed to pass through.
[0005]
[Problems to be solved by the invention]
Since the distance between the plurality of diffracted beams emitted from the AOM increases at a position sufficiently away from the AOM, it is easy to shield unnecessary diffracted beams, but a long optical path length is required, resulting in an increase in size of the apparatus. As a workaround, it is possible to reduce the size of the apparatus by folding the optical path with a mirror, but the apparatus configuration becomes complicated and adjustment becomes complicated.
As another method of the prior art for expanding the separation distance of a plurality of diffracted beams, there is a method of arranging a wedge substrate on the output end side of the AOM as shown in FIG. The plurality of diffracted lights 1 and 2 incident from the surface of the wedge substrate 3 are transmitted through a predetermined substrate thickness, reflected by the back surface of the wedge substrate 3, transmitted through the substrate again, and emitted from the surface of the wedge substrate 3. . The plurality of diffracted beams 1 and 2 that have been close to each other by the above steps are separated to some extent, and after being separated, an unnecessary diffracted beam can be shielded via the light shielding member 4 having the opening 4a. However, with this method, astigmatism occurs in the beam and the light condensing characteristic is deteriorated. Further, since the beam optical path is folded, the arrangement adjustment of the system becomes complicated when the beam synthesis of the three primary colors is performed in the subsequent stage of the system. Further, since it is necessary to install this system for each of the optical paths of the three primary colors, the arrangement of the system is further complicated.
The optical system described in Japanese Patent Laid-Open No. 9-5589 is clearly defined by a light-shielding plate having a pinhole that allows only a desired beam to pass through even a plurality of partially overlapping light beams having a small separation angle. Although there is an advantage that it can be separated, since the condensing points of the respective light beams are quite close to each other, the tolerance given to the configuration of the pinhole is not so large.
Ideally, it is desirable that an unnecessary diffraction beam can be shielded with an aperture larger than the modulation beam diameter, and that a long optical distance is not required.
[0006]
In the laser apparatus, it is desirable that the modulated beam is propagated in a parallel or nearly parallel state. When the beam diverges, it is necessary to increase the size of the rear optical system, which increases the cost. From the principle of the Gaussian propagation characteristics of laser beams, it is known that increasing the beam diameter improves the parallelism of the propagating beam. However, in applications such as laser markers, laser trimmers, and laser scan displays, the beam diameter is once increased. If the range is extended, the depth of focus when condensing the light last becomes shallow, and if the depth is small, the accuracy of the position of the processing surface and the screen becomes severe. From the above, it is rare that an optical system that increases the beam diameter and improves the parallelism of the propagating beam is employed. In short, it is desirable to propagate the beam while maintaining a state as close as possible to the beam diameter emitted from the laser.
[0007]
In an apparatus that modulates and uses lasers having different wavelengths, AOMs corresponding to laser beams having different wavelengths have the same problem. When each of the beams having different wavelengths passes through the AOM, the number of diffracted beams increases. Of these, a method of efficiently shielding unnecessary diffracted beams simultaneously is desired.
Although the desired modulated beams selected by the light shielding means have different wavelengths, an apparatus that condenses or scans these beams can be considered. In this case, an apparatus configuration capable of matching the condensing positions and spot sizes of beams having different wavelengths is desired.
[0008]
In view of these problems, the main object of the present invention is to shield unnecessary diffracted beams emitted from the AOM within a short optical path. The main object is to enable control of the parallelism of a desired modulated beam.
Furthermore, it aims at the following things.
Increases the diffracted light separation effect and relaxes the precision of parts processing and assembly adjustment. In a laser apparatus that uses lasers having different wavelengths at the same time, all unnecessary diffraction beams are simultaneously shielded, and a desired modulated beam is converted into a parallel beam. The modulated beams having different wavelengths are condensed at the same focal position. The beams with different wavelengths modulated by AOM are scanned and condensed at the same position, and the focused spot size is also made the same.
And it aims at providing the beam scanning apparatus using these laser optical apparatuses.
[0009]
[Means for Solving the Problems]
  In order to solve the above problem, in the invention according to claim 1 of the present application,Having a plurality of laser light sources emitting laser beams of different wavelengths,Emitted from laser light sourceTale-The beam is modulated by acousto-optic elements for each wavelength.To extract the desired modulated beamIn laser optics,
  A plurality of diffracted beams modulated by the acoustooptic deviceAmong them, all diffracted beams having different diffraction angles from the desired modulated beam are made unnecessary diffracted beams,
  Consists of total reflection mirror and dichroic mirrorWith a deflection device,
  The deflecting device combines the desired modulated beam so that the optical axes thereof coincide with each other on the same straight line, and configures the unnecessary diffracted beam to pass through an optical path different from the desired modulated beam,
  SaidBehind the deflection device,The optical axis is matched with the optical axis of the desired modulated beam.The afocal optical system that makes up the beam expanderPrepared,
  The afocal optical system isThe first optical element of the afocal optical system including an achromatic lens, a light shielding member, and the second optical element of the afocal optical system including an achromatic lens are arranged in this order,
  The light shielding member is disposed in close contact with the second optical element;The center of the aperture is arranged to coincide with the optical axis of the desired modulated beam synthesized coaxially, and only the desired modulated beam is passed through and separated from the optical axis of the desired modulated beam by a distance. An opening having a size that prevents the unnecessary diffraction beam from passing therethrough;
  Only the desired modulated beamAfter passing through the second optical element,Output as parallel light fluxWith a configuration to
  Behind the second optical elementIsIt has an achromatic condensing lens, and further has one or more beam scanning means for scanning the desired modulated beam behind the achromatic condensing lens.
[0010]
  In the invention according to claim 2,2. The laser optical device according to claim 1, wherein the beam scanning means is at least one of a polygon mirror and a galvanometer mirror.It is characterized by that.
[0011]
  In invention of Claim 3,3. The laser optical device according to claim 1, wherein a separation frequency of a plurality of diffracted beams is varied by changing a carrier frequency of an ultrasonic wave input to the acousto-optic modulator in accordance with a wavelength of an incident laser beam. Are made equal to each other regardless of the acousto-optic modulator, and the optical axis of the desired modulated beam is synthesized coaxially by the deflecting device and the optical path of the unnecessary diffracted beam is matched.It is characterized by that.
[0015]
[Action]
  According to invention of Claim 1,The optical axes of a plurality of desired modulated beams having different wavelengths are made to coincide with each other, and an afocal optical system including an achromat lens and a light shielding member are used to block an unnecessary diffracted beam, and the desired modulated beam is parallel light. Since the beam is scanned while the emitted light is collected by an achromatic condenser lens, when applied to a display device or the like, the desired modulated beam is focused on a predetermined image plane position regardless of the difference in wavelength. Can be tied.  According to invention of Claim 2,The desired modulated beam is deflected and scanned by at least one of a polygon mirror and a galvanometer mirror.  According to invention of Claim 3,An unnecessary diffraction beam does not cause a difference in optical path due to a difference in wavelength.
[0018]
Embodiment
  FIG. 1 shows a first embodiment of the present invention.Reference exampleFIG.
  In FIG. 1, a parallel beam emitted from a laser light source 1 and incident on an AOM 2 is modulated by the AOM 2 and emitted as a plurality of diffracted beams such as zero-order light and ± first-order light. The plurality of diffracted beams emitted from the AOM 2 have a separation angle that depends on the wavelength of the incident beam and the carrier frequency of the ultrasonic vibration input to the AOM. Although the separation angle of these diffracted beams is small, by placing an optical element 31 having a negative power immediately after that, the diffracted beam emitted from the optical element 31 is expanded at a short optical distance due to its refraction effect. it can. By arranging the optical element 31 so that the optical axis coincides with the desired modulated beam 5 to be used thereafter, the desired modulated beam 5 passes through the center of the lens, so that the optical axis of the beam goes straight without being refracted. However, the desired modulated beam 5 incident as a parallel light beam is emitted as a divergent light beam. Behind the optical element 31, the beam other than the desired beam, that is, the unnecessary diffracted beam 6 is sufficiently separated from the desired modulated beam 5 in terms of distance, so that the light shielding member having an opening 4a of an appropriate size. 4 makes it possible to easily shield only the unnecessary diffraction beam 6. Here, the appropriate size of the opening 4a is preferably larger than the diameter of the desired modulated beam for the reason already described. However, it must be set so that unnecessary diffraction beams do not enter. The power of the optical element 31, the distance from the optical element 31 to the light shielding member 4, and the size of the opening 4 a are set so that only a desired modulated beam can be obtained even if there is an unavoidable variation in component accuracy or the like. Decide.
  Here, the optical element may be a single lens or a compound lens composed of a plurality of lenses as long as the purpose is met. The point is that it can be optically handled as one lens. The same applies to the following description.
[0019]
  FIG. 2 shows a second embodiment of the present invention.Reference exampleFIG. The difference from FIG. 1 is that the optical element immediately after the AOM is an optical element 32 having a positive power.
  In FIG. 2, the beam optical axis of the unwanted diffracted beam has a separation angle with the desired modulated beam and appears to be divergent, but each beam is a parallel beam. Therefore, each beam refracted by the optical element is focused on a position that does not coincide with each other on the focal plane of the optical element. However, the beam optical axis of each beam converges slightly behind the focal position of the optical element and then diverges.
  Although the separation angle of each beam before entering the optical element 32 is small, the separation angle of the diffracted beam can be expanded at a short optical distance by increasing the lens power of the optical element 32. By making the optical axis of the optical element 32 coincide with the beam optical axis of the desired modulated beam 5 actually used, the beam optical axis of the desired modulated beam 5 goes straight without being refracted. However, the desired modulated beam 5 incident on the optical element 32 as a parallel light beam travels as a divergent light beam after the focal position of the optical element 32. The unwanted diffracted beam 6 is focused on the focal plane of the optical element 32 as described above, but its beam optical axis intersects the beam optical axis of the desired modulated beam behind the focal position. Since the beam optical axis of the unnecessary diffracted beam 6 is separated from the beam optical axis of the desired modulated beam 5 behind the intersection of the two beam optical axes, as in the first reference example, By selecting the position, only the desired modulated beam can be extracted.
  When the position of the light shielding member 4 is set at a position close to the intersection of the two beam optical axes, the distance between the two beam optical axes becomes smaller than the distance between the two beam optical axes when entering the optical element 3. There is a possibility that. In order to prevent this problem from occurring, the position where the light shielding member 4 is placed needs to be at least the same distance as the distance from the optical element 32 to the intersection position, preferably more away from the intersection.
[0020]
  FIG. 3 shows a third embodiment of the present invention.Reference exampleFIG. The difference from FIG. 2 is that an optical element 7 having a positive power is disposed behind the light shielding member 4, and an afocal beam converter is formed in combination with the optical element 32. That is, they are arranged coaxially so that the focal position of the optical element 32 and the focal position of the optical element 7 coincide.
  In FIG. 3, a desired modulated beam 5 which is a parallel light beam incident on the optical element 32 is once converged to the focal position by the optical element 32 and proceeds as it is as divergent light, and the optical element 7 which is the rear group of the beam converter. After passing through the opening 4 a of the light shielding member 4 disposed immediately before the light, the light enters the optical element 7. As described above, since the optical element 7 is confocal with the optical element 32, the desired modulated beam 5 travels on the optical axis again as a parallel beam after passing through the optical element 7.
  In the drawing, the position of the light shielding member 4 is set to be before the beam enters the optical element 7. However, considering only the effect of shielding the unwanted diffraction beam, the beam is replaced with the optical element instead of the light shielding member 4. Immediately after exiting 7, a light shielding member 4 ′ may be placed as shown by the dotted line in the figure. This isReference examples andThe same applies to all the embodiments. In general, unnecessary light fluxes are usually blocked as soon as possible to prevent unnecessary scattered light in the optical element.
  Although not shown, even if the optical element 7 having a positive power is placed immediately after the light shielding member 4 in the optical system of FIG. 1 and the divergent light beam from the optical element 31 is converted into a parallel light beam, FIG. The same effect as the reference example can be obtained. This configuration has an advantage that the optical path length can be shortened compared to the configuration of FIG.
[0021]
  Figure 4 also shows a commonly used modulation method.It is shown belowIt is a figure of the reference example which shows that this invention can be applied.
  In FIG. 4, the parallel beam emitted from the laser light source 1 is focused on the modulation position of the AOM 2 by the optical element 8 having a positive power. By doing so, the modulation speed can be increased, and this configuration is often used.
  The light beam modulated by the AOM 2 becomes a plurality of divergent diffracted beams and exits the AOM 2. These light beams are returned to parallel light beams by the optical element 9 having the same positive power. That is, the optical element 8 and the optical element 9 also constitute an afocal system. As in the third embodiment, the light beam that has passed through the optical element 9 can be extracted as a parallel light beam only by the beam converter that includes the light shielding member 4 therein.
  However, since the light beam modulated by the AOM 2 has a divergence angle, if this angle is larger than the separation angle, it partially overlaps and cannot be separated by the light shielding member 4.
Originally, since the separation angle of AOM2 is not so large, in order to further reduce the divergence angle of the light beam, the distance between the optical element 8 and AOM2 must be sufficiently large, which makes it difficult to reduce the size of the apparatus.
[0022]
  FIG.Beam converter used in the present inventionIt is the figure which expanded a part for demonstrating more preferable conditions.
  The beam converter is divided into a beam expander and a beam condenser depending on the magnitude relationship between the focal lengths of the front group and the rear group. In the present invention, both can be adopted in principle, but the configuration of the beam expander is more suitable only for the purpose of increasing the degree of separation.
  In FIG. 5, the focal lengths of the optical element 3 and the optical element 7 of the afocal lens group forming the beam converter are defined as f1 and f2, respectively. Here, f1 <f2, that is, the focal length of the optical element in the rear group is made larger than that in the front group. Accordingly, the distance between the optical axis of the desired modulated beam and the beam optical axis of the unnecessary diffracted beam at the position of the light shielding member 4 disposed substantially in close contact with the rear group is set as the optical element of the front group. Can be made larger by the ratio of f2 / f1 than the distance between the optical axes of the two beams before entering the beam. However, this configuration becomes a beam expander, and the beam diameter of the outgoing beam is larger than the beam diameter of the incident beam at the same ratio as described above. As already described, since it is not a good idea to make the beam diameter too large, f1 and f2 are determined in consideration of other factors.
[0023]
  FIG. 6 shows the present invention.Basic configuration of the main part of the embodimentFIG.
  In the figure, reference numerals 1-1 and 1-2 denote laser light sources having different wavelengths. The wavelengths of the emitted light are assumed to be λ1 and λ2. The parallel beams emitted from the respective light sources are modulated by the corresponding AOMs 2-1 and 2-2, respectively, and each emits a plurality of diffracted beams. The plurality of diffracted beams having the wavelength λ1 emitted from the AOM 2-1 are deflected by the total reflection mirror 10 which is the first deflecting device. The plurality of diffracted beams having the wavelength λ2 emitted from the AOM2-2 are deflected by a dichroic mirror which is a second deflecting device that transmits the wavelength λ1 and totally reflects the wavelength λ2. At this time, among the plurality of diffracted beams emitted from the AOM 2-1, the beam optical axis of the desired modulated beam 5-1, and among the plurality of diffracted beams emitted from the AOM 2-2, the desired modulated beam 5- The total reflection mirror 10 and the dichroic mirror 11 are arranged so that the two beam optical axes coincide with each other on the same straight line. As a result, a plurality of desired modulated beams having different wavelengths appear as one beam, and become a combined beam 52. Unnecessary diffracted beam 6 deflected by both mirrors 10 and 11 passes through a different optical path from synthesized beam 52.
[0024]
  In general, it is assumed that the laser beam emitted from the laser light source 1 has good parallelism, but may be slightly divergent as it passes through several optical systems. In that case, as shown by a two-dot chain line in the figure, a collimating lens 92 having a weak positive power may be inserted in front of the afocal lens system as necessary.
  The combined beam 52 and the unwanted diffraction beam 6 areThird reference exampleBy passing the same afocal system, the light shielding member 4 can extract only the combined beam 52 from the optical element 73.
  By the way, the combined beam 52 includes different wavelength components, λ1 and λ2. Therefore, if a lens system including chromatic aberration is used as the optical element 32 or the optical element 7 as shown in FIG. 3, the combined beam emitted from the optical element 7 has both wavelengths parallel due to the difference in refractive index depending on the wavelength. It becomes impossible to align with the luminous flux. Therefore, all the optical elements used here are constituted by an achromatic lens system, that is, an achromatic lens system. As a result, the combined beam 52 incident on the optical element 33 and exiting the optical element 73 becomes a parallel light beam regardless of the difference in wavelength.
  As described above, in order to facilitate understanding, the case of two colors has been described. However, in general, three primary colors are generally used for applications such as a display, and it is obvious that this embodiment can also be applied to the case of three colors. is there. However, in this case, if the third wavelength is λ3, a dichroic mirror or a bandpass filter that transmits λ1 and λ2 and totally reflects λ3 is used as the third deflecting device. Other configurations are apparent from the figure. In the following drawings, the description is for the case of two colors, but a configuration for three colors is assumed.
[0025]
  7 controls the diffracted beam which is unnecessary particularly easily in the configuration of FIG.MethodFIG.
  The diffraction angle of the beam diffracted by the AOM varies depending on the wavelength of the incident light beam. The ultrasonic vibration applied to the AOM is a combination of a carrier wave and a modulation wave for signal. The modulated wave is amplitude modulated and appears as a change in intensity of the modulated beam. The difference in the frequency of the carrier wave appears in the difference in the interval between the lattice fringes generated inside the AOM. As a result, it appears as a difference in the separation angle of the diffracted beam.
  In FIG. 6, if light beams having different wavelengths are modulated using carrier waves having the same frequency in AOMs 2-1 and 2-2, the optical path of an unnecessary diffracted beam has a different separation angle depending on the wavelength as shown in the figure. After passing through the dichroic mirror 11, they pass through different optical paths.
  In FIG. 7, the frequency of the carrier wave applied to the AOMs 2-1 and 2-2 is varied, and as a result, the control is performed so that the separation angles of unnecessary diffracted beams are substantially equal to each other. Accordingly, the AOM 2-2 and the AOM 2-1 via the total reflection mirror 10 are optically symmetrically arranged with respect to the dichroic mirror 11. As a result, the unnecessary diffracted beam 62 passing through the dichroic mirror 11 follows substantially the same optical path, although the wavelengths are different. By doing so, the opening 4a of the light shielding member 4 can be set to the most efficient size.
[0026]
  FIG. 8 shows the present invention.The fruitEmbodimentFurther configurationFIG. 2 shows an optical system that can be applied to a scanning device or the like. This is a configuration in which an achromatic condensing lens system 12 having a positive power is further arranged behind the optical element 73 configured as shown in FIG.
  The combined beam 52 having different wavelengths emitted from the optical element 73 becomes a parallel light flux and enters the achromatic condenser lens system 12. Therefore, the combined beam 52 behaves as if it is a beam of one wavelength, and the light flux of any wavelength is focused on the focal position of the achromatic condenser lens 12 system. Does not occur.
[0027]
Although there is no wavelength difference in the focal length of the achromatic condensing lens system 12, the spot diameter when focused is changed depending on the wavelength. The size of the spot diameter is proportional to the wavelength and the F value (aperture ratio, that is, focal length / beam diameter). When the wavelength is long, the F value can be reduced by increasing the beam diameter. Therefore, the integrated value of the wavelength and the F value can be made substantially the same by controlling the beam diameter. Based on the above principle, it is possible to make the condensing spot diameters of the combined beam 52 having a wavelength difference uniform. This effect is effective for the use of a laser scan display. As a specific configuration, a laser light source having a different output beam diameter is adopted, or although not shown, a beam expander or somewhere from the laser light source to a deflection device such as a total reflection mirror or a dichroic mirror This can be achieved by inserting a beam condenser.
[0028]
  FIG. 9 shows the present invention.The fruitEmbodimentOverall pictureFIG.
In FIG. 9, reference numerals 13 and 14 denote beam scanning means. In the illustrated example, 13 represents a rotating polygon mirror and 14 represents a galvanometer mirror. The optical system that makes the light beam incident on the beam scanning means has at least a part of any one of the optical systems shown in FIGS. FIG. 9 shows an example in which the optical system shown in FIG. 8 is applied as it is.
[0029]
FIG.Configuration shown inIn the above description, the polygon mirror 13 and the galvanometer mirror 14 are described as examples of beam scanning means, but the reference numeral 13 may be a galvanometer mirror. Alternatively, reference numeral 14 may be a polygon mirror. In the configuration shown in the figure, the polygon mirror 13 scans the modulated beam 5 in the horizontal direction on the paper surface, and the galvanometer mirror 14 scans in the vertical direction on the paper surface. According to the configuration of FIG. 9, the modulated beam 52 is scanned in two axes, that is, two-dimensionally, using two beam scanning means. However, if the surface to be scanned moves and there is no need for two-dimensional scanning, only one scanning means is required.
Although not shown, it is possible to display a distortion-free image on a flat display if an f / θ lens used in an image forming apparatus or the like is used together and the optical system before and after the scanning means is adapted to that. It is.
[0030]
As the beam scanning device, a laser marker, a laser trimmer, a laser scan display, and the like can be considered, but the present invention is not necessarily limited thereto. According to the apparatus configuration means of the present invention, an unnecessary beam can be easily shielded with a short optical path length. The desired modulated beam can pass through the opening of the light shielding member having an opening larger than the beam diameter, so that diffraction due to the opening edge does not occur. Can be formed. Furthermore, since it is possible to avoid an unnecessary beam reaching the processing surface or the screen, it is possible to improve processing quality or image quality. Alternatively, since beams having different wavelengths can be condensed at the same focal position, processing with different spot diameters can be performed without changing the position of the processing member. Alternatively, in the laser scan display that irradiates the beam spot of three colors on the screen, the focal position shift and the spot size difference due to the wavelength causing the color shift do not occur.
[0031]
【The invention's effect】
  Claim 1Described inAccording to the invention, an unnecessary diffracted beam among a plurality of diffracted beams emitted from the AOM can be shielded in a short optical path, does not include an unnecessary component,Multiple different wavelengthsA device that extracts only the desired modulated beam without loss of light quantity can be miniaturized.Thus, an apparatus can be obtained in which a difference in optical path and a difference in condensing point do not occur due to a difference in wavelength.
  Claim 2According to the invention ofA beam scanning device in which the desired modulated beam is deflected and scanned by at least one of a polygon mirror and a galvanometer mirror can be provided.
[0032]
  ClaimDescribed in 3According to the invention, in a laser apparatus using lasers having different wavelengths at the same time, all unnecessary diffraction beams are simultaneously shielded by a single light shielding member, and a plurality of desired modulated beams having different wavelengths are obtained as combined beams. It can be handled as if it were one beam.
[Brief description of the drawings]
FIG. 1 shows the first of the present invention.Reference exampleFIG.
FIG. 2 shows the second of the present invention.Reference exampleFIG.
FIG. 3 is a diagram for explaining a third embodiment of the present invention.
[Fig.4] Also used for commonly used modulationIt is shown belowIt is a figure of the reference example which shows that this invention can be applied.
[Figure 5]Beam converter used in the present inventionIt is the figure which expanded a part for demonstrating more preferable conditions.
FIG. 6 of the present inventionBasic configuration of the main part of the embodimentFIG.
FIG. 7 is a diagram illustrating a configuration in which unnecessary diffraction beams are controlled to be easily processed in the configuration of FIG.MethodFIG.
FIG. 8The fruitEmbodimentFurther configurationFIG.
FIG. 9The fruitEmbodimentOverall pictureFIG.
FIG. 10 is a reference diagram showing an example of a conventional technique for enlarging the separation distance of a plurality of diffraction beams.
[Explanation of symbols]
  1 Laser light source
  2 AOM
  31, 32, 33 Optical elements
  4 Shading member
  5 Desired modulated beam
  52 Composite beam
  6 Unnecessary diffraction beam
  7 Optical elements
  10 Total reflection mirror
  11 Dichroic mirror
  12 Achromatic condenser lens system
  13, 14 Beam scanning means

Claims (3)

A plurality of laser light sources for emitting a laser beam of different wavelengths, Les Zabimu emitted from the laser light sources, laser optical apparatus for each wavelength and modulated by the acousto-optic element takes out the desired modulated beam In
Among the plurality of diffracted beams modulated by the acoustooptic device, all diffracted beams having a diffraction angle different from the desired modulated beam are made unnecessary diffracted beams,
It has a deflecting device composed of a total reflection mirror and dichroic mirror ,
The deflecting device combines the desired modulated beam so that the optical axes thereof coincide with each other on the same straight line, and configures the unnecessary diffracted beam to pass through an optical path different from the desired modulated beam,
Behind the deflecting device comprises an afocal optical system constituting the desired modulated beam of a beam expander to match the optical axis to the optical axis,
The afocal optical system includes a first optical element of the afocal optical system including an achromatic lens, a light shielding member, and a second optical element of the afocal optical system including an achromatic lens, in this order,
The light shielding member is disposed in close contact with the second optical element, and the center of the opening is disposed so as to coincide with the optical axis of the desired modulated beam synthesized coaxially, and only the desired modulated beam is disposed. An aperture of a size that does not pass through the unwanted diffracted beam separated from the optical axis of the desired modulated beam through a distance;
A configuration in which only the desired modulated beam is output as a parallel beam after passing through the second optical element ,
Behind the second optical element comprises a achromat condenser lens, further the laser optical device characterized by having one or more beam scanning means for scanning the desired modulated beam to the rear.   2. The laser optical apparatus according to claim 1, wherein the beam scanning means is at least one of a polygon mirror and a galvanometer mirror.   In the laser optical device according to claim 1, by separating the carrier frequency of the ultrasonic wave input to the acousto-optic modulator according to the wavelength of the incident laser beam, the separation angles of the plurality of diffraction beams are Laser optical apparatus characterized in that they are equal to each other regardless of the acousto-optic modulation element, the optical axis of the desired modulated beam is coaxially synthesized by the deflecting device, and the optical path of the unwanted diffracted beam is made coincident .

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