JPH1068801A - Antireflection film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an antireflection film having the min. number of layers which hardly causes loss in light quantity by reflection and shows no double refraction by forming layers in such a manner that the angles of oblique vapor deposition from the objective body for vapor deposition make a right angle between a first layer and a second layer. SOLUTION: The layers are formed in such a manner that angles of oblique vapor deposition from the objective body make a right angle between the first layer 9 and the second layer 11. Namely, the antireflection film consists of the oblique vapor deposition film 9 as the first layer and the oblique vapor deposition film 11 as the second layer. The oblique vapor deposition film 11 is formed as a double refraction film having the center line 7 of the objective body as the fast phase axis and having the center line 8 as the slow phase axis and these optical axes are opposite to those of the oblique vapor deposition film 9 as the first layer. Therefore, the obtd. antireflection film has the same refractive index as a film having non-reflection conditions. By arranging the optical axes of the first layer 9 and the second layer 11 perpendicular to each other, double refraction of the films can be compensated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antireflection film for an optical component using an obliquely deposited film.

[0002]

2. Description of the Related Art Hitherto, there has been known an antireflection film in which an optical material is obliquely vapor-deposited on an object to be vapor-deposited to reduce the refractive index to an optimum refractive index (JP-A-7-27).
902, 5-80202).

FIG. 9 shows a conventional apparatus for manufacturing an anti-reflection film using an obliquely deposited film, FIG. 10 shows the state of scattering of an object to be deposited and a deposited material at the time of conventional deposition, and FIG. 2 shows a cross section of FIG. Reference numeral 21 denotes a vacuum chamber;
Reference numeral 5 denotes an optical material to be deposited, and reference numeral 26 denotes a crucible.
The object 23 is attached to the substrate holder 22 obliquely with respect to the virtual scattered line 24 of the object to be evaporated. Further, in order to make the deposition thickness uniform, the deposition is performed while rotating about the center of the substrate holder.

[0004]

As an optical material of the antireflection film, a metal fluoride such as MgF2 or SiO2 is generally used.
Metal oxides such as are used. The antireflection film is for preventing the reflection of light at the interface. For example, to prevent the reflection of light at the interface between the optical component and air, the refractive index of the optical component is set to Ns and the refractive index of air is set to No. If (≒ 1), the refractive index Nu must be selected to be (Ns * No) ^1/2 , and the optical thickness (film thickness d * Nu) needs to be 1/4 of the wavelength (hereinafter, non-reflective). Condition).

The wavelength used is 795 nm, and glass (BK) is used for the substrate.
7, when the refractive index is 1.51), the optimum refractive index of the antireflection film is 1.23. However, as a general optical material, there is only MgF2 having a refractive index of 1.38, and the reflectance is 1. 3
%. Therefore, an antireflection film is used which utilizes the fact that the refractive index is reduced by obliquely depositing an optical material.

However, since the film simply obliquely deposited has birefringence, when it is used as an antireflection film of a quarter-wave plate, for example, the phase difference of the quarter-wave plate causes the birefringence of the antireflection film. The phase difference adds to the error.

[0007] Further, as Example 2 of JP-A-5-80202, an antireflection film using an obliquely deposited film composed of four layers orthogonal to each other is shown. Although not disclosed by this configuration, it is possible to cancel birefringence incidentally, but it is difficult to manufacture because of a complicated structure in which the number of layers of the antireflection film is at least four, and it is costly. Was something.

An object of the present invention is to provide an antireflection film using an obliquely deposited film having no birefringence with a minimum number of antireflection films.

[0009]

In order to solve this problem, the antireflection film of the present invention has at least two obliquely deposited films, and the oblique deposition angle with respect to the object to be deposited is set to be different between the first and second layers. An obliquely deposited film formed so as to be orthogonal and using an obliquely deposited film as an anti-reflection film, or an obliquely deposited film obtained by performing oblique deposition while rotating an object to be deposited on an axis orthogonal to substantially the center of the object to be deposited as an anti-reflection film It is used.

Thus, an antireflection film having no birefringence with a minimum number of layers and little loss of light due to reflection can be obtained.

[0011]

The invention according to claim 1 has at least two obliquely deposited films formed by obliquely depositing an optical material,
The oblique deposition film is formed so that the oblique deposition angle with respect to the object to be deposited is orthogonal to the first and second layers. The obliquely deposited film has birefringence, but is birefringent by orthogonalizing the first and second layers. Can be canceled, and the refractive index is reduced by oblique deposition.Therefore, it is necessary to use an optical material with a refractive index larger than the required refractive index and change the incident angle of the deposition material to the object to be deposited. The refractive index under the non-reflection condition is obtained, and there is almost no loss in the amount of light due to reflection.

According to a second aspect of the present invention, there is provided an object having an oblique deposition film obtained by performing oblique deposition while rotating an object to be deposited about an axis orthogonal to a substantially center of the object. Birefringence can be canceled by performing oblique vapor deposition while rotating the film about an axis perpendicular to the center of the vapor deposition material, and has the same effect as the first aspect.

An embodiment of the present invention will be described below with reference to FIGS. The same members are given the same numbers.

(Embodiment 1) FIGS. 1 to 5 show an antireflection film according to an embodiment 1 of the present invention.
Denotes an apparatus for producing an anti-reflection film, 1 denotes a vacuum chamber, 5 denotes an optical material to be deposited, and 6 denotes a crucible. The object 3 is attached to the substrate holder 2 obliquely with respect to the virtual scattered line 4 of the object to be evaporated. or,
In order to make the deposition thickness uniform, deposition is performed while rotating about the center of the substrate holder.

FIG. 2 shows the state of the object to be deposited and the scattered state of the object when the first layer is deposited. Reference numerals 7 and 8 denote the center lines of the object to be deposited, respectively, which are orthogonal to each other. direction,
7 corresponds to an axis orthogonal to 8. FIG. 3 shows a cross section of the first layer after the vapor deposition. In the vapor deposition apparatus, the vapor deposition is performed by arranging the substance 3 to be inclined with respect to the flying direction of the optical material, so that the surface is oblique from the surface of the substance. The obliquely deposited film 9 is formed as a columnar structure growing in the direction. Oblique deposition film 9
Is a birefringent film having 8 as a fast axis and 7 as a slow axis in FIG.

FIG. 4 is a view showing the state of scattering of the object to be deposited and the vapor deposition material at the time of vapor deposition of the second layer. FIG. 5 shows a cross section after the second layer is deposited, 9 shows a first layer obliquely deposited film, 11 shows a second layer obliquely deposited film, and the obliquely deposited film 11 shown in FIG. 7 is the fast axis and 8
Becomes a birefringent film having a slow axis as the first layer, and the first obliquely deposited film 9
And a birefringent film having an optical axis opposite to the above.

The operation of the thus configured antireflection film will be described below.

As an example, the wavelength used is 795 nm, the substrate is glass (BK7, refractive index 1.51), and the obliquely deposited film is S
When iO2 (refractive index: 1.47) is used and the incident angle of the deposition material on the object to be deposited is approximately 30 degrees, the refractive index of the obliquely deposited film using SiO2 is 1.23, which is the same refractive index as in the non-reflection condition. Can be obtained, and the birefringence can be canceled by making the optical axes of the first and second layers perpendicular to each other.

As described above, according to the present embodiment, it is possible to obtain an antireflection film having almost no loss of light amount due to reflection and having no birefringence.

(Embodiment 2) Next, FIGS. 6 to 8 show an antireflection film according to a second embodiment of the present invention, and FIG. 6 shows an apparatus for manufacturing the antireflection film. Is deposited while being rotated on an axis perpendicular to the center of the object and the center of the object.

FIG. 7 shows the state of the object to be deposited and the scattered state of the material to be deposited at the time of evaporation. Reference numerals 7 and 8 denote the center lines of the object to be deposited, respectively, which are orthogonal to each other. Rotate around the center of.

FIG. 8 shows a cross section after the vapor deposition. The vapor deposition object 3 is arranged in the vapor deposition apparatus so as to be inclined with respect to the flying direction of the optical material, and the vapor deposition is performed while rotating about an axis perpendicular to the center of the vapor deposition object. Is performed, an oblique deposition film 12 that grows spirally in an oblique direction from the surface of the deposition target is formed.

The operation of the antireflection film configured as described above will be described below.

The birefringence is canceled by arranging the object 3 to be inclined with respect to the direction of flight of the optical material in the evaporation apparatus and performing evaporation while rotating the object 3 around an axis perpendicular to the center of the object. By using this obliquely deposited film as an antireflection film, the same operation as in the first embodiment can be obtained.

As described above, according to the present embodiment, it is possible to obtain an antireflection film having almost no loss of light amount due to reflection and having no birefringence.

It is needless to say that the same applies to the obliquely deposited film formed not only by vapor deposition but also by sputtering or the like, and the same applies to a multilayer antireflection film.

[0027]

As described above, according to the present invention, there is obtained an advantageous effect that an antireflection film having almost no loss of light amount due to reflection and having almost no birefringence and substantially the same as under non-reflection conditions can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic view of an apparatus for manufacturing an antireflection film according to an embodiment of the present invention.

FIG. 2 is a diagram showing a state of scattering of an object to be deposited and a deposition material during deposition of a first layer according to the embodiment of FIG. 1;

FIG. 3 is a diagram showing a cross section after deposition of a first layer according to the embodiment of claim 1;

FIG. 4 is a diagram showing a state of scattering of an object to be deposited and a deposition material during deposition of a second layer according to the embodiment of FIG. 1;

FIG. 5 is a diagram showing a cross section after deposition of a second layer in the embodiment of claim 1;

FIG. 6 is a schematic diagram of an apparatus for manufacturing an antireflection film according to the second embodiment.

FIG. 7 is a diagram showing a state of scattering of an object to be deposited and a deposition material during deposition according to the embodiment of claim 2;

FIG. 8 is a diagram showing a cross section after vapor deposition in the embodiment of claim 2;

FIG. 9 is a schematic view of a conventional antireflection film manufacturing apparatus.

FIG. 10 is a diagram showing a state of scattering of an object to be deposited and a deposition material during conventional deposition.

FIG. 11 is a diagram showing a cross section after conventional evaporation.

[Explanation of symbols]

 1,21 Vacuum tank 2,22 Substrate holder 3,23 Deposition object 4,24 Virtual scattered line of deposition 5,25 Optical material to be deposited 6,26 Crucible 7,27,8,28 Center of deposition object Line 9 Obliquely deposited film of first layer 10 Virtual scattered line of deposited material of second layer 11 Obliquely deposited film of second layer 12, 29 Obliquely deposited film

Claims (2)

[Claims] 1. An optical material having at least two obliquely deposited films formed by obliquely depositing an optical material, wherein oblique deposition angles with respect to an object to be deposited are formed so as to be orthogonal to each other in a first layer and a second layer. Anti-reflection film. 2. An antireflection film having an obliquely deposited film obtained by performing oblique deposition while rotating an object to be deposited about an axis orthogonal to a substantially center of the object to be deposited.