JPH0915410A - Production of optical element and production of metal mold for optical element - Google Patents

Abstract

PURPOSE: To provide a process for efficiently and exactly producing an optical element having desired patterns on a curved surface and a process for producing a metal mold for the optical element capable of efficiently and exactly producing the metal mold for producing such optical element. CONSTITUTION: The optical element having the desired patterns is produced by projecting the prescribed patterns of a reticle 6 to a processed layer 4 consisting of a photosensitive material formed on the curved surface 3 of a substrate 2 by using a projecting optical system 7 having the shape of the image plane corresponding to the curved surface 3 of the substrate 2, then developing the patterns. The metal mold having the desired patterns on the curved surface is produced by using the optical element formed by projecting the prescribed patterns of the reticle 6 to the processed layer 4 consisting of the photosensitive material formed on the curved surface 3 of the substrate 2 by using the projecting optical system 7 having the curvature the image plane corresponding to the curved surface of the substrate 2, then developing the patterns or further the optical element formed by transferring the desired patterns to the substrate 2 by anisotropic etching as a master disk.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical element, and more particularly to a method for producing an optical element having a predetermined diffraction grating structure on a curved surface and a die for producing the optical element.

[0002]

2. Description of the Related Art Diffractive optical elements are used in various fields because they have characteristics that refractive optical elements do not have. Among them, a diffractive optical element formed on a curved substrate is also known. For example, in a spectroscopic device in the vacuum ultraviolet region, a concave diffraction grating in which a reflective diffraction grating is formed on a concave substrate is widely used. Alternatively, even a diffractive lens that has been conventionally formed on a flat surface may have a great effect on aberration correction by forming it on a spherical surface, as disclosed in, for example, JP-A-6-242373 and JP-A-6-250081. It is shown in the publication.

Conventionally, the following method has been proposed as a method for manufacturing a diffraction grating on a curved surface. As disclosed in Japanese Patent Application Laid-Open No. 55-9865, a diffraction groove engraving device (a device called a so-called ruling engine) reciprocates a grating groove engraving tool with a cylindrical cam as a guide, and a groove width. The cylindrical cam is moved up and down corresponding to the position of the grid groove in the direction, and thereby the grid groove engraving tool is moved along the spherical surface of the grid material to engrave. As disclosed in Japanese Patent Laid-Open No. 61-72202, first, a flat diffraction grating having a predetermined shape is formed on a flexible material and deformed into a predetermined curved surface, and then a curved diffraction grating material is formed on the flexible material. The curved diffraction grating is manufactured by bringing the curved diffraction grating material into contact with each other and curing the curved diffraction grating material. As disclosed in Japanese Patent Laid-Open No. 4-16910, first, as shown in FIG. 11A, a mold 21 having a cavity 22 formed by lathe processing is used. As shown in FIG. 11B, the ultraviolet curable resin 23 is applied and the spherical lens 24 is inserted. Next, the ultraviolet ray from the ultraviolet ray lamp 25 is applied to the ultraviolet ray curable resin 23 through the spherical lens 24 to cure the ultraviolet ray curable resin 23. After that, the spherical lens 24 is peeled off from the mold 21, and as shown in FIG. 11C, the correction lens layer 2 made of an ultraviolet curable resin.
An optical lens 27 having 6 is obtained.

[0004]

However, in the above method, although high-precision processing is possible, there is a problem that an expensive device is required, and one groove is formed in the diffraction grating. Since the main processing is performed, there is a problem that the processing time is long. Further, in the above method, when the curvature of the predetermined curved surface becomes large, distortion occurs when the flat flexible material is deformed into the predetermined curved surface, and thus the shape accuracy of the diffraction grating decreases. Further, in the above method, since a mold is used, it is suitable for mass production, but as shown in FIG. 11B, the spherical lens 2 is used.
Since the ultraviolet ray curable resin 23 is irradiated with ultraviolet rays through 4, the material of the substrate (the spherical lens 24 in this case) forming the correction lens layer (diffraction grating) 26 has a transmittance in the ultraviolet region. There is a problem that it is limited to.

The first object of the present invention was made by paying attention to the above-mentioned conventional problems, and manufacture of an optical element capable of efficiently and accurately manufacturing an optical element having a desired pattern on a curved surface. It is intended to provide a method.

Further, a second object of the present invention is to provide a method for manufacturing an optical element mold capable of efficiently and accurately manufacturing a mold for manufacturing an optical element having a desired pattern on a curved surface. It is the one we are trying to provide.

[0007]

In order to achieve the above first object, a method of manufacturing an optical element according to the present invention is such that a processing layer made of a photosensitive material is formed on the curved surface of a substrate having at least one curved surface. The step of forming and a reticle having a predetermined pattern are projected on the processing layer by a projection optical system having an image plane shape that is substantially the same as the curved surface of the substrate, and the desired pattern is exposed on the processing layer. And a step of developing the exposed processed layer.

In order to achieve the above-mentioned second object, in the method of manufacturing a mold for an optical element of the present invention, a step of forming a processed layer made of a photosensitive substance on the curved surface of a substrate having at least one curved surface. And a step of projecting a reticle having a predetermined pattern onto the processing layer by a projection optical system having a shape of an image plane substantially the same as the shape of the curved surface of the substrate, and exposing the processing layer to a desired pattern. A step of developing the exposed processed layer, and a step of forming a mold for manufacturing an optical element using the substrate having the developed processed layer as a master disc. Is.

Further, in the method for manufacturing a mold for an optical element according to the present invention, a step of forming a processed layer made of a photosensitive material on the curved surface of a substrate having at least one curved surface, and a reticle having a predetermined pattern. Is projected onto the processing layer by a projection optical system having an image plane shape that is substantially the same as the curved surface shape of the substrate, and a desired pattern is exposed on the processing layer; and the exposed processing layer is exposed. A developing step,
And a step of transferring the developed shape of the processed layer to the substrate by anisotropic etching, and a step of forming a mold for manufacturing an optical element using the substrate as a master disc. It is a thing.

[0010]

According to the invention of claim 1, a projection optical system having a shape of an image plane corresponding to the curved surface of the substrate is used for the processing layer made of a photosensitive material formed on the curved surface of the substrate, and Project a predetermined pattern. Here, considering the aberration of the projection optical system in the region of the third-order aberration, when the object (reticle) is a plane, the image plane is generally a spherical surface. The magnitude of the curvature of the image plane at this time can be represented by the curvature P or the radius of curvature ρ, and the value can be obtained by the Petzval theorem as follows.

(Equation 1)

Therefore, when the curved surface of the substrate on which the processing layer is formed is, for example, a spherical surface having a radius of curvature R, if the projection optical system has an image surface curvature of the radius of curvature R as described above,
It is possible to project along the curved surface of the substrate, which makes it possible to expose a desired pattern from a predetermined pattern on the reticle onto the curved surface of the substrate. Then, by developing the processed layer, an optical element having a desired pattern on the curved surface is manufactured.

In a second aspect of the present invention, a projection optical system having a curvature of an image plane corresponding to the curved surface of the substrate is used for a processing layer made of a photosensitive material formed on the curved surface of the substrate, and a reticle of the reticle is used. A predetermined pattern is projected, the desired pattern is exposed on the processed layer, and then the processed layer is developed and used as a master master to manufacture a mold having a desired pattern on a curved surface.

According to a third aspect of the present invention, a projection optical system having a curvature of image plane corresponding to the curved surface of the substrate is used for the processing layer made of a photosensitive material formed on the curved surface of the substrate. A predetermined pattern is projected, a desired pattern is exposed on the processed layer, the processed layer is developed, and then the pattern of the processed layer is transferred to a substrate by anisotropic etching, which is used as a master disc. A mold having a desired pattern on a curved surface is manufactured.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. In the drawings described below, the drawings are exaggerated or simplified for easy understanding in a range not departing from the spirit of the present invention. In the first embodiment of the present invention, as shown in FIG. 1, for example, an aberration-correcting concave diffraction grating 1 used for a spectroscope in the vacuum ultraviolet region is manufactured. This aberration-correcting concave diffraction grating 1 has, for example, a diffraction grating having a laminar groove shape formed into an elliptical shape with unequal intervals in order to correct various aberrations generated in the concave diffraction grating formed with a linear grating with equal intervals. It is formed, and is generally of a reflective type.

First, as shown in the sectional view of FIG.
A curved surface 3 having a predetermined radius of curvature R for forming a pattern is formed on one surface of the substrate 2, and a processing layer 4 made of a photosensitive material such as photoresist is formed on the curved surface 3. Here, as the substrate 2, a ceramic-based material, a glass-based material, a metal-based material, or the like is used.

Next, the processed layer 4 shown in FIG.
A desired pattern is exposed using the exposure optical system shown in FIG.
The exposure optical system shown in FIG. 3 has an illumination system 5, a reticle 6 and a projection lens 7. The illumination optical system 5 includes a lamp 8, a collimator lens 9, a filter 10, and an integrator 1.
1, an aperture stop 12 and a condenser lens 13,
The reticle 6 is configured to be irradiated with illumination light from the lamp 8 via the collimator lens 9, the filter 10, the integrator 11, the aperture stop 12 and the condenser lens 13.

On the reticle 6, a grating pattern in which light transmitting portions and opaque portions are alternately arranged at a predetermined pitch is formed, and this grating pattern is formed on the image plane of the projection lens 7 at a predetermined magnification. To Here, the projection lens 7 is given a field curvature with a radius of curvature R, and the projection lens 7
The curved surface 3 of the substrate 2 is aligned with the image plane of 1.

In this way, the reticle 6 is illuminated by the illumination system 5 and the image of the lattice pattern thereof is formed on the processing layer 4 through the projection lens 7, so that the entire surface of the curved surface 3 in a predetermined range is covered. , The processing layer 4 is exposed with a desired lattice pattern according to the lattice pattern of the reticle 6.

In the exposure optical system shown in FIG. 3, the projection magnification of the projection lens 7 can be arbitrarily selected.
The pattern pitch of the diffraction grating is generally micron (μm)
Since it is often on the order, it is desirable to use a reduction system having a magnification of 1/10, 1/5, etc. in consideration of the ease of manufacturing the reticle 6 and the influence of dust. Further, as the aberration of the exposure optical system, if the influence of higher-order aberrations than the above-mentioned third-order aberration cannot be ignored, the optical design may be performed while actually evaluating the aberration of the optical system by a ray tracing method or the like. In this case, aberrations other than the field curvature of the projection lens 7 are sufficiently corrected in order to prevent deterioration of the performance of the manufactured diffraction grating.

As described above, using the reticle 6,
Concave substrate 2 whose curved surface 3 is a spherical surface having a predetermined radius of curvature
After exposing the processed layer 4 of 1., this processed layer 4 is developed to form a desired lattice pattern corresponding to the lattice pattern of the reticle as shown in the sectional view of FIG. After that, anisotropic etching such as RIE (reactive ion etching) is performed, and as shown in the sectional view of FIG.
The grating pattern is transferred to the substrate 2 to obtain the aberration-correcting concave diffraction grating 1 shown in FIG.

If the substrate 2 is made of a metallic material and has a sufficient reflectance in the wavelength range to be used, it is not always necessary to form a reflective film on the formed grating pattern, but ceramics are necessary. When using a glass-based or glass-based material, it is desirable to form a reflective film such as an aluminum film on the surface of the lattice pattern after transferring the lattice pattern to the substrate 2.

As described above, according to this embodiment, since the exposure and etching steps are used to form the diffraction grating on the curved surface 3, once compared with the case of using the conventional ruling engine, Diffractive optical elements can be mass-produced extremely efficiently by simply manufacturing a reticle.

In the second embodiment of the present invention, as shown in FIG. 2A, the substrate 2 having the processing layer 4 formed on the curved surface 3 is used and the same steps as those in the first embodiment are carried out. A blaze-type diffraction grating is manufactured. Therefore, in this embodiment,
The lattice pattern drawn on the reticle 6 shown in FIG. 3 is provided with the photosensitive characteristic of the processing layer 4 and the transmittance distribution characteristic considering the lattice pattern formed on the substrate 2. That is, the reticle 6 is a so-called transmittance modulation type mask. First, the processing layer 4 is exposed as shown in FIG. 3 using such a blaze type reticle.

Next, as shown in FIG. 4A, the processed layer 4
Is developed to form a lattice pattern, which is then anisotropically etched to transfer a desired blazed lattice pattern to the substrate 2 as shown in FIG. afterwards,
A reflective film is formed as needed.

Also in this embodiment, since the blazed concave diffraction grating can be manufactured by using the exposure and etching processes, it is possible to mass-produce the diffractive optical element very efficiently as in the first embodiment. it can.

Although not shown, in the second embodiment, a sine wave type diffraction grating is manufactured in the same manner by giving the reticle 6 a sinusoidal transmittance distribution in consideration of the photosensitive characteristics of the processing layer 4. can do. Further, not only the aberration correction type concave diffraction grating but also a concave diffraction grating having a linear diffraction grating can be manufactured in the same process by forming a linear diffraction grating pattern on the reticle 6.

In the third embodiment of the present invention, a diffractive lens (grating lens) having a concentric blazed pattern formed on a curved surface is manufactured. Therefore, first, as shown in FIG. 5A, a convex curved surface 3 made of a spherical surface having a predetermined radius of curvature R ′ is formed on one surface of the substrate 2, and the processing layer 4 is formed on the curved surface 3. To do.

After that, the processing layer 4 is exposed using an optical system having the same structure as the exposure optical system shown in FIG. In this embodiment, since the grating lens is manufactured, the reticle 6 (see FIG. 3) that constitutes the exposure optical system has a transmission pattern corresponding to a desired pattern formed on the processing layer 4, as shown in FIG. Try to have rate modulation. Further, the projection lens 7 is made to have a convex field curvature having a radius of curvature R ′ corresponding to the curved surface 3 of the substrate 2.

Next, as shown in FIG. 5B, the processed layer 4
Is developed to form a desired lattice pattern, and then anisotropic etching, for example, argon ion etching is performed on this to transfer the lattice pattern to the substrate 2 as shown in FIG. Get the lens.

In this embodiment, when the transmission type grating lens is manufactured, the substrate 2 can be made of a plastic material, a glass material or the like.
In this case, the use efficiency of light at the wavelength used can be improved by applying an antireflection coating to the substrate 2 if necessary. In the case of manufacturing a reflective grating lens, the substrate 2 may be made of a plastic material, a glass material, a ceramic material, a metal material, or the like. However, when a glass-based material having a low reflectance is used, it is desirable to form a reflective film on the diffraction grating surface as described above.

As described above, when manufacturing a grating lens in which a lattice pattern is formed on the convex curved surface 3, the reticle 6 is provided with a transmittance modulation corresponding to a desired pattern. It is possible to increase the degree of freedom in designing the curvature of the lens 3 and to disperse the lens power between the curved surface 3 and the diffraction grating surface, which is advantageous in that the pitch of the grating pattern can be set to a value that is easy to manufacture. .

In each of the above embodiments, the substrate 2 has a flat surface on one side and a concave or convex curved surface (spherical surface) on the other side, but both surfaces are spherical and one surface is spherical. It is also possible to manufacture diffractive optical elements having various optical characteristics by using various shapes such as the other surface having a cylindrical surface and both surfaces having aspherical surfaces.

FIGS. 7A to 7D are views for explaining the fourth embodiment of the present invention. In this example, a part of a mold for an optical element is manufactured. First, as shown in FIG.
As shown in, a processing layer 4 is formed on the curved surface 3 of the substrate 2,
An image of the reticle is projected and exposed on the processing layer 4 by using an optical system having the same configuration as the exposure optical system shown in FIG. In this embodiment, the reticle is a transmittance modulation mask for a blazed grating. Then, the processed layer 4 is developed to form a desired lattice pattern on the processed layer 4, as shown in FIG.

Next, as shown in FIG. 7C, a conductive metal, such as nickel, is deposited on the surface of the processed layer 4 by sputtering, vapor deposition or the like, using the substrate 2 after the development process as a master master. After forming the electrode body 14 by electroplating, as shown in FIG. 7D, electroforming is performed to deposit the nickel electroformed layer 15. Then, the nickel electroformed layer 15
Is peeled off, and the peeled nickel electroformed layer 15 is obtained as a part of the mold.

According to this embodiment, a part of the die is manufactured by an electroforming method that faithfully traces the shape of the master with respect to the master master having a diffraction grating whose groove cross-sectional shape is blazed. Can be manufactured with high precision. Moreover, since a part of this mold generally occupies the most important part in the optical element manufacturing among the molds composed of a plurality of members, if the optical element is manufactured using this, a high diffraction efficiency is obtained. Optical elements can be manufactured with high precision and in large quantities.

Further, since the pattern shape of the master master and the pattern shape of the optical element manufactured by using the mold manufactured using this master master are the same, the master at the time of manufacturing the master master. By measuring the shape of the master, the performance of the manufactured optical element can be predicted. Therefore, when a desired master disk is not obtained, there is also an advantage that the manufacturing of the mold can be redone before actually manufacturing the optical element using the master disk.

As a method for manufacturing an optical element using the mold manufactured in this embodiment, for example, a known plastic injection molding method or photopolymer method (2P method) can be used. Here, photopolymer method (2P method)
Forms an ultraviolet-curable resin (photopolymer) layer on a transparent substrate, presses a mold against the resin layer, and irradiates ultraviolet rays to cure the resin layer to produce an optical element. There are no temperature cycles compared to the injection molding method and therefore the process is shorter. Birefringence and coma are less likely to occur. The life of the mold can be extended. There is an advantage.

FIGS. 8A to 8E are views for explaining the fifth embodiment of the present invention. In this example, a part of a mold for an optical element is manufactured. First, as shown in FIG.
As shown in, a processing layer 4 is formed on the curved surface 3 of the substrate 2,
An image of the reticle is projected and exposed on the processing layer 4 by using an optical system having the same configuration as the exposure optical system shown in FIG. In this embodiment also, the reticle is a transmittance modulation mask for a blazed grating. Next, the processed layer 4 is developed to form a desired lattice pattern on the processed layer 4 as shown in FIG. 8B, and then anisotropic etching, for example, reactive ion etching is performed on this. , The lattice pattern is transferred to the substrate 2 as shown in FIG.

Next, using the substrate 2 having the transferred lattice pattern as a master disc, as shown in FIG.
A conductive metal, for example, nickel is deposited on the surface of the grid pattern side by sputtering, vapor deposition, or the like to form the electrode body 14, and then, as shown in FIG. 8E, electroforming treatment is performed to form a nickel electroformed layer. Deposit 15. Then, the nickel electroformed layer 15 is peeled off, and the peeled nickel electroformed layer 15 is removed.
As part of the mold.

According to this embodiment, the same effect as in the fourth embodiment can be obtained, and the number of steps is increased as compared with the fourth embodiment, but the shape of the processed layer 4 is transferred to the substrate 2 by anisotropic etching. Therefore, there is an advantage that the durability of the master master can be increased when the mold is repeatedly manufactured from the master master. As a method of manufacturing an optical element using this mold, the same method as the method described in the fourth embodiment can be adopted.

FIGS. 9A to 9C are views for explaining the sixth embodiment of the present invention. In this example, a part of a mold for an optical element is manufactured. First, as shown in FIG.
As shown in FIG. ₃ , a spherical concave curved surface 3 is formed on a substrate 2 made of, for example, Cr ₂ O ₃ (chromium oxide).
The processed layer 4 is formed on top. Then, an image of the reticle is projected and exposed on the processed layer 4 by using an optical system having the same configuration as the exposure optical system shown in FIG.

Next, the processed layer 4 is developed to form a desired lattice pattern on the processed layer 4 as shown in FIG. 9B, and then this is subjected to anisotropic etching, for example, argon ion etching. , A lattice pattern is transferred to the substrate 2 as shown in FIG. 9 (c), and this is obtained as a part of the mold.

According to this embodiment, the processing layer 4 is formed on the substrate 2.
After forming a grid pattern on the processed layer 4 by an exposure and development process, the grid pattern is transferred to the substrate 2 by anisotropic etching so as to be directly obtained as a part of the mold. There is an advantage that the manufacturing process can be simplified as compared with the case where the electroforming treatment is performed as in the fifth embodiment. In addition, since the lattice pattern is directly formed on the curved surface 3 of the substrate 2 by the exposure, development and etching steps, once the reticle is manufactured, the mold can be manufactured in an extremely short time and the mass production can be efficiently performed. Can be produced.

FIG. 10 is a diagram for explaining a method of manufacturing an optical element using the mold manufactured in the sixth embodiment. In this manufacturing example, a diffractive lens made of glass is manufactured. As the upper mold 16, the mold manufactured in the sixth embodiment is used, and as the lower mold 17, WC (tungsten carbide) is used as a main component. The top and bottom surfaces of the formed cylinder are mirror-polished. The upper surface of the lower mold 17 is coated with platinum to prevent fusion with glass. In this manufacturing example, the optical glass 1 is placed on the upper surface of the lower mold 17 with the optical glass 18 formed in the general shape of the diffractive lens to be manufactured.
After heating 8 above the glass softening point, the optical glass 18 is pressure-molded by the upper mold 16 to manufacture a diffractive lens made of glass.

As described above, since the glass diffraction grating can be formed by using the mold manufactured in the sixth embodiment, it is possible to obtain a diffraction lens which is resistant to humidity and temperature changes.

In the sixth embodiment, Cr ₂ O ₃ was used as the material of the substrate 2, but other mold materials such as WC,
It is also possible to use SiC (silicon carbide) or the like. However, when WC or SiC is used, it is desirable to coat platinum or TiN on the lattice pattern surface in advance in order to prevent fusion with glass when manufacturing an optical element made of glass.

Further, in the sixth embodiment, the curved surface 3 of the substrate 2 is spherical, but it may be another shape, for example, a parabolic surface. Of course, in this case, the projection lens 7 that constitutes the exposure optical system according to the shape of the curved surface 3 (see FIG. 3)
To design. Further, although only the field curvature is generated in the projection lens 7, it is also possible to generate distortion in addition. In this case, reticle 6
The grid pattern to be formed in 1 is calculated and created so as to have a desired grid pattern when projected on the curved surface 3 by the projection lens 7 having distortion.

Further, in manufacturing an optical element using the mold manufactured in the sixth embodiment, in addition to the method of press molding glass shown in FIG. 10, generally known plastic injection molding is used. Method and photopolymer method (2P
Method) can be used. Also, the shape of the optical element to be manufactured is not limited to the shape of a plano-convex lens with one surface being flat and the other surface being spherical, and other shapes, for example, both spherical surfaces, or both aspherical substrates are used. Thus, optical elements having various shapes can be manufactured.

Appendix 1. A step of forming a processing layer made of a photosensitive material on the curved surface of a substrate having at least one curved surface, and a reticle having a predetermined pattern having an image plane shape substantially the same as the curved surface shape of the substrate. Projecting onto the processing layer by a projection optical system to expose a desired pattern on the processing layer, developing the exposed processing layer, and anisotropically etching the shape of the developed processing layer. And a step of forming a part of a metal mold for manufacturing an optical element by the method described above. 2. The method of manufacturing an optical element according to claim 1, wherein the reticle is made of a transmittance modulation type mask. 3. The method for manufacturing a mold for an optical element according to claim 2, claim 3, or the above-mentioned Supplementary Note 1, wherein the reticle comprises a transmittance modulation type mask.

[0050]

According to the first aspect of the present invention, an optical element having a desired pattern can be efficiently and accurately manufactured on a surface different from a flat surface by an exposure process and a development process. Compared with the case of using a ruling engine, etc., it has high productivity and is suitable for mass production.

According to the second aspect of the present invention, a master master having a desired pattern on a surface different from the flat surface is obtained by the exposure step and the development step, and the mold is manufactured based on this master disk. The mold can be manufactured efficiently and accurately. Further, since the pattern shape of the master master and the pattern shape of the optical element manufactured using the mold manufactured using this master master are the same, the shape of the master master at the time of manufacturing the master master By measuring, the performance of the manufactured optical element can be predicted. Therefore, when a desired master disk is not obtained, there is also an advantage that the manufacturing of the mold can be redone before actually manufacturing the optical element using the master disk.

According to the invention described in claim 3, it is possible to obtain the same effect as that of the invention described in claim 2. further,
In the present invention, the desired pattern is transferred to the substrate and the processed layer has already been removed to be the master master, so that the processed layer is peeled off from the substrate in the mold manufacturing process, which is a factor that adversely affects optical performance. There is also an advantage that can reduce.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an aberration correction type concave diffraction grating manufactured in a first embodiment of the present invention.

FIG. 2 is a diagram for explaining the first embodiment of the present invention.

FIG. 3 is a diagram for explaining an exposure process of the first embodiment.

FIG. 4 is a diagram for explaining the second embodiment of the present invention.

FIG. 5 is also a diagram for explaining the third embodiment.

FIG. 6 is a diagram showing transmittance modulation characteristics of a reticle used in the third embodiment.

FIG. 7 is a diagram for explaining the fourth embodiment of the present invention.

FIG. 8 is likewise a diagram for explaining the fifth embodiment.

FIG. 9 is likewise a diagram for explaining the sixth embodiment.

FIG. 10 is a diagram for explaining an example of a method of manufacturing an optical element using the mold manufactured in Example 6;

FIG. 11 is a diagram for explaining a conventional technique.

[Explanation of symbols]

 1 Aberration-corrected concave diffraction grating 2 Substrate 3 Curved surface 4 Processing layer 5 Illumination system 6 Reticle 7 Projection lens 8 Lamp 9 Collimator lens 10 Filter 11 Integrator 12 Aperture diaphragm 13 Condenser lens 14 Electrode body 15 Electroformed layer 16 Upper mold 17 Lower mold 18 Optical glass

Claims (3)

[Claims] 1. A step of forming a processed layer made of a photosensitive material on the curved surface of a substrate having at least one curved surface, and a reticle having a predetermined pattern, which has an image substantially the same as the curved shape of the substrate. An optical element comprising: a step of projecting onto the processing layer by a projection optical system having a surface shape to expose a desired pattern on the processing layer; and a step of developing the exposed processing layer. Manufacturing method. 2. A step of forming a processed layer made of a photosensitive material on the curved surface of a substrate having at least one curved surface, and an image of a reticle having a predetermined pattern having substantially the same shape as the curved surface of the substrate. A step of projecting onto the processing layer by a projection optical system having a surface shape to expose a desired pattern on the processing layer; a step of developing the exposed processing layer; and a step of developing the processing layer. And a step of forming a mold for manufacturing an optical element, using the substrate as a master master, a method for manufacturing a mold for an optical element. 3. A step of forming a processing layer made of a photosensitive material on the curved surface of a substrate having at least one curved surface, and an image of a reticle having a predetermined pattern having substantially the same shape as the curved surface of the substrate. A step of projecting onto the processing layer by a projection optical system having a surface shape to expose a desired pattern on the processing layer; a step of developing the exposed processing layer; and a shape of the developed processing layer And a step of forming a mold for manufacturing an optical element using the substrate as a master master, and a method for manufacturing a mold for an optical element. .