JPH10142410A - Binary optical element and production of nonspherical composite optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a binary optical element usable in a UV region as well without depending on the refractive index of the base material by supplying metallic alcoholate to the surface of an optical element base material and pressing the same to form an oxide lay of a shape having ruggedness on this optical element base material. SOLUTION: A lens blank 7 made of quartz glass is arranged on a transfer mold 3 into which the product of hydrolysis of the Si alcoholate 6 is injected. The lens blank 7 is fixed by a clamp ring 5. Molding is executed while the relative positions of a mold 2 and the transfer mold 3 are kept monitored by a sensor 9 in such a manner that the desired positions are attained. The transfer mold 3 is formed by precision working a sintered hard alloy essentially consisting of WC to a diffraction pattern shape of a desired saw tooth shape in section. A diamond-like carbon film is formed at a prescribed thickness on its transfer surface. The transfer mold 3 and the lens blank 7 are released, by which the SiO2 layer having the diffraction pattern shape of the saw tooth shape in section is formed on the lens blank 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a binary optical element comprising a glass or plastic base material and an oxide layer formed on the base material and having a stepwise or sawtooth cross-sectional diffraction pattern. And a method for producing an aspherical composite optical element comprising a glass or plastic substrate and an aspherical oxide layer formed on the substrate.

[0002]

2. Description of the Related Art A binary optical lens having a stepwise or sawtooth-shaped diffraction pattern used in an optical system such as a camera, a laser beam printer, a copying machine, a facsimile, and an optical head for a magneto-optical recording medium. A method of manufacturing a binary optical lens in which a molten glass is injected into a molding die and molding the same, and a binary optical lens that forms a diffraction pattern shape having a step-like cross section or a sawtooth cross section by photolithography on the surface of the glass lens. Manufacturing methods are known.

However, the first of the above methods, the former of which can be mass-produced at low cost, has the disadvantage that optical characteristics such as a change in the focal length due to the tendency for sink marks to occur during cooling after molding and the like. There is a problem with accuracy. Further, the photolithography used in the second method, which is the latter, requires repeating the steps of resist application, exposure, etching, and cleaning, which has a problem of increasing costs.

[0004] Therefore, as a method of solving such a problem, an energy-curable resin is interposed between a mold and a glass or plastic substrate having a desired sectional stepwise or sawtooth-shaped diffraction pattern shape and cured. By doing so, a manufacturing method of a binary optical lens in which a resin layer having an optical surface on which the analysis pattern shape of a cross-sectional stepped shape of a mold or a sawtooth-shaped cross-section is transferred on the surface of the base material is put into practical use. ing.

According to this method, since the resin layer is a thin film, the influence of a change in the refractive index due to thermal expansion or heat is small, and furthermore, the occurrence of sink marks and distortion can be suppressed, and a low-cost binary Optical lenses can be mass-produced.
This manufacturing method is disclosed in detail in JP-A-6-88276, JP-A-6-254868, JP-A-7-112443, and the like.

[0006]

However, in the above-mentioned method for producing a binary optical lens in which a resin layer is formed on the surface of a base material, the usable energy-curable resin has a refractive index of 1.4 to 1.6 after molding. In the range,
In order to obtain a refractive index matching with the base material, the type (= refractive index) of glass or plastic that can be used as the base material is limited by the energy-curable resin. For this reason, this method cannot be applied to a substrate having a refractive index exceeding 1.6, which limits the degree of freedom in optical design. The energy-curable resin is cured by heat or ultraviolet light, and generally does not transmit light in the ultraviolet region. Therefore, there is a problem that a binary optical lens that can be used in the ultraviolet region cannot be provided by the above-described manufacturing method.

In addition to the above-mentioned binary optical lens, as a method of manufacturing an aspheric lens used in an optical system of a camera, a printer, a copying machine, a facsimile, etc., a transparent thermo-flexible resin is injected into a molding die. There is known a method of manufacturing a plastic lens which is formed by molding. However, this method can be mass-produced at low cost, but has a problem in optical characteristic accuracy such as a change in the focal length because sinking tends to occur during cooling after molding. Therefore, as a method of solving such a problem, similarly to the case of the binary optical lens described above, curing is performed by interposing an energy-curable resin between a mold having a molding surface of a desired optical shape and a glass or plastic substrate. By doing so, a method for manufacturing a so-called aspherical composite optical element has been put to practical use, in which an optical component having a resin layer having an optical surface on which the shape of a molding surface of a mold is transferred onto a substrate surface is molded.

According to this method, since the resin layer is a thin film, the influence of a change in the refractive index due to thermal expansion or heat is small, furthermore, the occurrence of sink marks and distortion can be suppressed, and the precision of the optical characteristics can be reduced. An improved aspheric lens can be mass-produced. Regarding this manufacturing method, Japanese Patent Publication No. 6-61872
No. 6-190941, 6-75875
No. 6-304936, No. 6-27016
No. 6, for example.

However, in the above-mentioned method for manufacturing an aspherical composite optical element, as described above for the binary optical lens, the usable energy-curable resin has a refractive index of about 1.4 to 1.6 after molding. In the range,
In order to obtain a refractive index matching with the base material, the type (= refractive index) of glass or plastic that can be used as the base material is limited by the energy-curable resin. For this reason, this method cannot be applied to a substrate having a refractive index exceeding 1.6, which limits the degree of freedom in optical design. The energy-curable resin is cured by heat or ultraviolet light, and generally does not transmit light in the ultraviolet region. Therefore, there is a problem that a composite optical element that can be used in the ultraviolet region cannot be provided by the above-described manufacturing method.

Accordingly, the present invention has been made in view of the above-mentioned problems, and has as its object to provide a binary optical element and an aspherical surface which can be used in the ultraviolet region without depending on the refractive index of a substrate. An object of the present invention is to provide a method for manufacturing an optical element.

[0011]

Means for Solving the Problems The above-mentioned problems are solved,
In order to achieve the object, a method for manufacturing a binary optical element according to the present invention comprises supplying metal alcoholate to an optical element substrate surface and pressing the optical element molding die to form irregularities on the optical element substrate. It is characterized in that an oxide layer having a shape is formed.

Further, in the method for manufacturing a binary optical element according to the present invention, when forming an oxide layer having a shape having irregularities on the optical element substrate, light having an energy of 4 eV or more is irradiated. Features. Further, in the method for manufacturing a binary optical element according to the present invention, the shape having irregularities formed on the optical element substrate is a step-shaped cross-section or a diffraction pattern having a saw-tooth cross-section. .

In the method for manufacturing a binary optical element according to the present invention, the optical element base is made of quartz. In the method for manufacturing a binary optical element according to the present invention, the metal alcoholate is silicon alcoholate. Further, in the method for manufacturing a binary optical element according to the present invention, the metal alcoholate is a composite of two or more metal alcoholates.

Further, in the method for manufacturing an aspherical composite optical element according to the present invention, a metal alcoholate is supplied to the surface of an optical element substrate and pressed by an optical element molding die to form an aspherical surface on the optical element substrate. Is characterized by forming an oxide layer having Further, in the method for manufacturing an aspherical composite optical element according to the present invention, when forming an oxide layer having an aspherical shape on the optical element substrate, light having energy of 4 eV or more is irradiated. I have.

In the method of manufacturing an aspherical composite optical element according to the present invention, the optical element base is made of quartz. In the method for manufacturing an aspherical composite optical element according to the present invention, the metal alcoholate is silicon alcoholate. In the method for manufacturing an aspherical composite optical element according to the present invention, the metal alcoholate is a composite of two or more metal alcoholates.

[0016]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. [First Embodiment] A first embodiment has a stepped or sawtooth cross section used for an optical system such as a camera, a laser beam printer, a copying machine, a facsimile, and an optical head for a magneto-optical recording medium. In a binary optical lens having a diffraction pattern shape, a hydrolysis product of metal alcoholate is used in place of the energy-curable resin, and 4e
An object of the present invention is to provide a method of manufacturing a binary optical lens that can be used in the ultraviolet region without depending on the refractive index of a substrate by irradiating light having energy of V or more.

The binary optical lens having a stepwise or sawtooth-shaped diffraction pattern according to the present embodiment is made of a glass material or a plastic material, and is formed on a lens blank from which optical distortion has been removed. Is formed by irradiating a high-energy light with an oxide layer made of a metal alcoholate whose refractive index matches that of the base material forming the layer.

Further, the method of manufacturing a binary optical lens having a diffraction pattern shape having a stepwise sectional shape or a sawtooth sectional shape is airtight at the time of assembly, can be divided into at least two parts, and has a lens forming surface or a sectional shape. Using a mold in which at least one surface forming a diffraction pattern shape having a stepped shape or a sawtooth cross section is made of a material that transmits light of 4 eV or more, a lens blank is placed in a cavity having a desired shape, and the lens blank is placed in the cavity. After filling the gap between the mold surface with a metal alcoholate having the same refractive index as the lens blank, light of 4 eV or more is irradiated from the outside of the molding die to change it into an oxide layer.

The metal alcoholate used here is a single alcoholate represented by M (OR) n.
Is a metal such as Si, Ti, Al, Zr, Ta, and Hf, and (OR) n is an alkoxyl group. Here, n is the valence of the metal element in the metal alcoholate, and is usually 4 for Si, 3 for Al, and the like. By mixing these two or more kinds of metal alcoholates in a certain ratio, the range of the refractive index of the oxide formed from the mixed metal alcoholates n =
An arbitrary refractive index can be obtained at 1.45 to 2.2.
For example, if the ratio of Si to M (Ti, Al, Zr) is 4: 1, it can be expressed by (Si4n / 5Mn / 5) On-1 (OR) 2n + 2. Specific examples include Si (OC ₂ H ₅ ) ₄ : silicon tetraethoxide, Al (OisoC ₃ H ₇ ) ₃ : aluminum isoproxide, Ti (OisoC ₃ H ₇ ) ₄ : titanium isoproxide, and the like. The refractive index of the mixed alcoholate film in the metal alcoholate is determined by Roger W Philli.
ps, Jerry W Dodds, Applied
Optics, Vol. 20, no. 1, pp40 ~ 4
7, for example, in the hydrolysis product of a mixed alcoholate of Si and Zr, n = 1.45-2.0, S
In the hydrolysis product of a mixed alcoholate of i and Al, n =
The refractive index can be changed in the range of 1.45 to 1.6. In particular, when used in the ultraviolet region, Si, Al, Z
Alcohols of r and Hf can be used. Further, as a metal alcoholate that can be used in a high energy region of 5 eV or more (wavelength of 248 nm or less), there are alcoholates of Si and Al. Among them, various Si alcoholates can be used, for example, ethyl silicate Si ₅ O
₄ (OC ₂ H ₅ ) ₁₂ or the like may be selected. In addition, SiOnOn-1 (O) such as silicon tetraethoxide Si (OC ₂ H ₅ ) _{4
C 2 H 5) 2n + 2} SinOn-1 represented by (OR) 2n + 2 (R is 1 or more n a substituted or unsubstituted hydrocarbon group) and RnS
i (OR) 4-n or the like can be used.

In order to increase the stability of the metal alcoholate to moisture and the sensitivity to light, a β-diketone such as ethyl acetoacetate, acetylacetone or benzoylacetone is used in an amount of 0.01 to 1.0 mol based on the metal element. May be weighed. This is because β-diketones, such as ethyl acetoacetate, acetylacetone, and benzoylacetone, coordinate with the metal atom of the metal alcoholate to form a metal chelate, thereby increasing the stability of the metal alcoholate against moisture. In addition, since the metal chelate of β-diketone is decomposed by irradiation with ultraviolet light, the curing reaction of the metal alcoholate can be suppressed until irradiation with ultraviolet light.

In a method of manufacturing a binary optical lens having a diffraction pattern shape having a stepped cross section or a sawtooth cross section, a desired shape, for example, a stepped cross section or
After dripping or pouring Si alcoholate whose viscosity has been adjusted by causing a condensation reaction over several hours to several days, for example, into a super-precision processed mold having a diffraction pattern shape having a sawtooth cross section, Place the lens blank. The mold includes a transfer mold for transferring a predetermined surface shape to the alcoholate layer and a body mold that movably holds the transfer mold to define the outer peripheral surface of the alcoholate layer. A desired shape is obtained by detecting the position with a sensor. Here, the Si alcoholate whose viscosity has been previously adjusted by hydrolysis is used. The conditions and catalyst for the hydrolysis are not particularly limited, and the hydrolysis may be performed according to a conventional method. After reaching the desired viscosity, a β-diketone such as ethyl acetoacetate, acetylacetone, or benzoylacetone may be added to suppress the curing reaction until irradiation with ultraviolet light. After this, hydrolysis and polycondensation reactions are promoted by irradiating light with energy of 4 eV or more through an annular body mold,
Si alcoholate changes into an amorphous SiO ₂ film. At this time, the alcohol or ester of the solvent is volatilized from the opening. Since the metal alcoholate changes into an oxide, it has a high adhesiveness with the mold material. Therefore, in order to improve the releasability of the transfer mold and the lens blank, Pt or the like having a small adhesiveness with the oxide as the mold material is used. An alloy of Pt, or a carbon-based material such as a diamond-like carbon film, diamond, glassy carbon, pyrolytic carbon, and high-density graphite, or a fluorine-based material is suitable. Excimer laser, harmonics of YAG laser, excimer lamp, SOR light, and the like can be used as the high energy light for irradiation. After the irradiation of high-energy light changes the Si alcoholate into a SiO ₂ film,
By applying a mechanical external force or ultrasonic vibration to the body mold and the transfer mold to release the mold, a binary optical lens having a diffraction pattern shape of a cross-sectional stepwise or sawtooth cross-section of a composite mold can be obtained. Since the Si alcoholate changes to an amorphous SiO ₂ film, it has the same refractive index as the same as the lens blank and has the same refractive index. Therefore, the lens blank material effectively has a diffraction pattern shape with a stepped cross section or a sawtooth cross section. This is equivalent to making a binary optical lens. At the stage of producing the hydrolysis product of Si alcoholate, the state of the gel formed varies depending on the amount of water added. The amount of water to Si alcoholate was 10 to 25 in molar ratio. Molar ratio of 10
When it is less than 2, the gel becomes powdery and the molar ratio is 2
If it exceeds 5, cracks may occur in the SiO ₂ film. Further, a β-diketone such as ethyl acetoacetate, acetylacetone, or benzoylacetone may be added to the hydrolysis product having reached a desired viscosity to suppress the curing reaction until irradiation with ultraviolet rays.

Further, since thermal energy is not used when converting the metal alcoholate into an oxide film, the present invention can be applied to a case where the lens blank is not only glass but also plastic. Hereinafter, specific examples will be described with reference to the drawings. (First Embodiment) FIG. 1 is a side sectional view showing the structure of a mold used in this embodiment. In the figure, 1 is a molding die, 2 is a trunk die, 3
Is a transfer mold, 5 is a clamp ring, 6 is a metal alcoholate, 7 is a lens blank, and 9 is a position sensor.

FIG. 2 is a side sectional view showing a state in which a binary optical lens having a diffraction pattern shape of a compound type having a stepped sectional shape or a sawtooth sectional shape is formed. In the figure, 10 is an oxide layer of metal alcoholate, 11 is 4 eV
The above is high energy light. 1 and 2,
The transfer product 3 was injected with the hydrolysis product of Si alcoholate. The hydrolysis product of Si alcoholate is Si (OC ₂
H _{5) 4:} Using 25 g, Si alcoholate against 14 moles of water and 0.03 mole of HCl, and those left viscosity adjustment with an aqueous solution of C ₂ H ₅ OH in 30 ml 1 day. A lens blank 7 made of quartz glass is arranged on a transfer mold 3 into which a hydrolysis product of Si alcoholate is injected, and after fixing the lens blank with a clamp ring 5, a relative position between the body mold 2 and the transfer mold 3 is desired. The molding was performed while monitoring with the sensor 9 so as to be in the position of. At this time, the wavelength 146 nm
Was irradiated from the clamp ring 5 side for 40 minutes using the excimer lamp as a light source. The transfer type is an ultra-precision processing of a cemented carbide mainly composed of WC into a desired diffraction pattern with a sawtooth cross section, and a 70 nm thick diamond-like carbon film on the transfer surface is used. Was. Thereafter, the transfer mold 3 and the lens blank 7 were released by a mechanism (not shown). The formed SiO ₂ layer was amorphous and had sufficient mechanical strength without any cracks or peeling off from the lens blank even after release.

In addition, the sample of Si
When the refractive index of the O ₂ film was measured by an ellipsometer, the wavelength was 632.8 nm, which was the same as that of the lens blank 1.4.
It was 6. Even when the fabricated binary optical lens having a sawtooth cross-section diffraction pattern shape was used for a KrF excimer laser optical system or an ArF excimer laser optical system, problems such as a decrease in transmittance and damage due to laser did not occur.

(Second Embodiment) The material used for forming the shape in the first embodiment was Si (OC ₂ H ₅ ) ₄ : 25 g, and 50 mol% of Al (OisoC ₃ H) based on Si alcoholate. ₇ ) ₃ and 1
7 mol water, 0.3 g HCl, 37.6 g C ₂ H ₅ O
The same apparatus as in the first embodiment, except that an aqueous solution of H was allowed to stand for 1.5 days to adjust the viscosity, and a mixture of ethyl acetoacetate and 0.05 mol based on the total amount of Si and Al was used. Was used to form a desired shape on a glass (BK7) lens blank under the same conditions. Thereafter, the transfer mold and the lens blank were released by the same mechanism as in the first embodiment. The formed Al ₂ O ₃ —SiO ₂ layer was amorphous and had sufficient mechanical strength without any cracks or peeling off from the lens blank even after release from the mold.

The Al sample of the sample prepared in the same manner
_When the refractive index of the ₂ O ₃ —SiO ₂ film was measured by an ellipsometer, the wavelength was 632.8 nm, which was 1.52, which is the same as that of the lens blank. Even when the manufactured binary optical lens having a sawtooth-shaped diffraction pattern shape was used for a lens optical system for a camera, problems such as a decrease in transmittance, cracks, and mold release did not occur.

(Third Embodiment) The material used for forming the shape in the first embodiment was Si (OC ₂ H ₅ ) ₄ : 25 g, and 50 mol% of Al (OisoC ₃ H) with respect to Si alcoholate. ₇ ) ₃ and 1
7 mol water, 0.3 g HCl, 37.6 g C ₂ H ₅ O
The same apparatus as in the first embodiment was used except that an aqueous solution of H was allowed to stand for 1.5 days to adjust the viscosity and acetylacetone was mixed with 0.1 mol according to the total amount of Si and Al. Under the same conditions, a desired shape was formed on a plastic lens blank (Zeonex-280, manufactured by Zeon Corporation). Thereafter, the transfer mold and the lens blank were released by the same mechanism as in the first embodiment. Molded Al
_{The 2} O ₃ —SiO ₂ layer was amorphous and had sufficient mechanical strength without cracking or peeling off from the lens blank even after release. In addition, Al _{2 of} a sample prepared in the same manner.
When the refractive index of the O ₃ —SiO ₂ film was measured by an ellipsometer, the wavelength was 632.8 nm, which was 1.53, which is the same as that of the lens blank. Even when the manufactured binary optical lens having a stepwise diffraction pattern shape was used for a camera lens optical system, problems such as a decrease in transmittance, cracking, and peeling did not occur.

(Fourth Embodiment) The material used for forming the shape in the first embodiment was Si (OC ₂ H ₅ ) ₄ : 25 g, and 20 mol% of Ti (OisoC ₃ H) based on Si alcoholate. ₇ ) ₄ and 1
5 mol water, 0.3 g HCl, 37.6 g C2 H5 O
An aqueous solution of H was left for 2 days to adjust the viscosity, and a mixture of benzoylacetone and 0.1 mol based on the total amount of Si and Al was used, and the apparatus shown in FIGS. 3 and 4 was used. Under the same conditions, a desired shape was formed on a glass (SK12) flat lens blank. Thereafter, the transfer mold and the flat lens blank were released by the same mechanism as in the first embodiment. The apparatus shown in FIGS. 3 and 4 has the same configuration as that of the apparatus used in the first embodiment except that the cross section of the transfer surface of the mold is step-shaped. The description is omitted by attaching the reference numerals. Molded TiO ₂ −
The SiO ₂ layer was amorphous and had sufficient mechanical strength without cracks or release from the flat lens blank even after release. In addition, TiO _{2 of} a sample produced in the same manner was used.
When the refractive index of the SiO ₂ film was measured by an ellipsometer, the wavelength was 632.8 nm, which was 1.58, which is the same as that of the flat lens blank. Even when the manufactured binary optical lens having a stepwise diffraction pattern shape was used for a camera lens optical system, problems such as a decrease in transmittance, cracking, and peeling did not occur.

[Second Embodiment] In a second embodiment, in an aspheric lens used for an optical system such as a camera, a printer, a copying machine, and a facsimile, hydrolysis of metal alcoholate instead of energy-curable resin is performed. Using the product, 4
An object of the present invention is to provide a method of manufacturing an aspherical composite optical element that can be used in the ultraviolet region without depending on the refractive index of a substrate by irradiating light having energy of eV or more.

The aspheric lens according to the present embodiment is made of a glass material or a plastic material, and is formed on a lens blank from which optical distortion has been removed by using a metal alcoholate whose refractive index matches that of the base material forming the lens blank. The oxide layer is formed by high-energy light irradiation. The method for manufacturing an aspherical composite optical element according to the present embodiment has a hermetic property at the time of assembly, can be divided into at least two, and at least one surface forming a lens molding surface is made of a material that transmits light of 4 eV or more. Using a mold, the lens blank is placed in a cavity of a desired shape, and in a gap between the lens blank and the mold surface,
After filling with a metal alcoholate having the same refractive index as the lens blank, light of 4 eV or more is irradiated from the outside of the molding die to change the oxide layer into an oxide layer.

The metal alcoholate used here is a single alcoholate represented by M (OR) n.
Is a metal such as Si, Ti, Al, Zr, Ta, and Hf, and (OR) n is an alkoxyl group. Here, n is the valence of the metal element in the metal alcoholate, and is usually 4 for Si, 3 for Al, and the like. By mixing these two or more kinds of metal alcoholates in a certain ratio, the range of the refractive index of the oxide formed from the mixed metal alcoholates n =
An arbitrary refractive index can be obtained at 1.45 to 2.2.
For example, if the ratio of Si to M (Ti, Al, Zr) is 4: 1, it can be expressed by (Si4n / 5Mn / 5) On-1 (OR) 2n + 2. Specific examples include Si (OC ₂ H ₅ ) ₄ : silicon tetraethoxide, Al (OisoC ₃ H ₇ ) ₃ : aluminum isoproxide, Ti (OisoC ₃ H ₇ ) ₄ : titanium isoproxide, and the like. The refractive index of the mixed alcoholate film in the metal alcoholate is determined by Roger W Philli.
ps, Jerry W Dodds, Applied
Optics, Vol. 20, no. 1, pp40 ~ 4
7, for example, in the hydrolysis product of a mixed alcoholate of Si and Zr, n = 1.45-2.0, S
In the hydrolysis product of a mixed alcoholate of i and Al, n =
The refractive index can be changed in the range of 1.45 to 1.6. In particular, when used in the ultraviolet region, Si, Al, Z
Alcohols of r and Hf can be used. Further, as a metal alcoholate that can be used in a high energy region of 5 eV or more (wavelength of 248 nm or less), there are alcoholates of Si and Al. Among them, various Si alcoholates can be used, for example, ethyl silicate Si ₅ O
₄ (OC ₂ H ₅ ) ₁₂ or the like may be selected. In addition, SiOnOn-1 such as silicon tetraethoxide Si (OC ₂ H ₅ ) _{4
(OC 2 H 5) 2n +} 2 SinOn-1 represented by (OR) 2n + 2 (R
Is a substituted or unsubstituted hydrocarbon group and n is 1 or more) or Rn
Si (OR) 4-n or the like can be used.

In the method of manufacturing an aspherical optical element according to the present embodiment, a Si alcoholate whose viscosity is adjusted by, for example, causing a condensation reaction to an ultra-precisely processed mold having a desired shape, for example, an aspherical shape, is used. Is dropped or injected, and a lens blank made of quartz is arranged. The mold includes a transfer mold for transferring a predetermined surface shape to the alcoholate layer and a body mold that movably holds the transfer mold to define the outer peripheral surface of the alcoholate layer. A desired shape is obtained by detecting the position with a sensor. Here, the Si alcoholate used beforehand is hydrolyzed. The conditions and catalyst for the hydrolysis are not particularly limited, and the hydrolysis may be performed according to a conventional method. Thereafter, by irradiating light having an energy of 4 eV or more through an annular body, hydrolysis and polycondensation reactions are promoted, and the Si alcoholate changes to an amorphous SiO2 film. At this time, the alcohol or ester of the solvent is volatilized from the open portion. Since the metal alcoholate changes into an oxide, it has a high adhesiveness with the mold material. Therefore, in order to improve the releasability of the transfer mold and the lens blank, Pt or the like having a small adhesiveness with the oxide as the mold material is used. Pt alloy or diamond-like carbon film, diamond, glassy carbon,
Carbon-based materials such as pyrolytic carbon and high-density graphite and fluorine-based materials are suitable. Excimer laser, harmonics of YAG laser, excimer lamp, SOR light, and the like can be used as the high energy light for irradiation. After the high-energy light irradiation changes the Si alcoholate into a SiO ₂ film, a composite aspherical lens can be obtained by applying a mechanical external force or ultrasonic vibration to the body mold and the transfer mold and releasing them. . Si alcoholate is amorphous SiO
Since it changes into _two films, it has the same refractive index and the same quality as the lens blank, which is equivalent to effectively forming an aspherical lens with the lens blank material. At the stage of preparing the hydrolysis product of Si alcoholate, the state of the gel formed varies depending on the amount of water added. The amount of water to Si alcoholate was 10 to 25 in molar ratio.
When the molar ratio is smaller than 10, the gel becomes powdery, and when the molar ratio is larger than 25, cracks may occur in the SiO2 film.

Further, since heat energy is not used when converting a metal alcoholate into an oxide film, the present invention can be applied to a case where the lens blank is made of plastic as well as glass. Hereinafter, specific examples will be described with reference to the drawings. (First Embodiment) FIG. 5 is a side sectional view showing the structure of a mold used in this embodiment. In the figure, 21 is a molding die, 22 is a drum die, 23 is a transfer die, 24 is a clamp ring, 25 is a metal alcoholate, 26 is a lens blank, and 27 is a position sensor.

FIG. 6 is a side sectional view showing a state in which a composite optical element is formed. In the figure, 28 is an oxide layer of a metal alcoholate, and 29 is high energy light of 4 eV or more. The hydrolysis product of Si alcoholate was injected into the transfer mold 3 shown in FIGS. The hydrolysis product of Si alcoholate was 25 g of Si (OC ₂ H ₅ ) ₄ , 10 mol of water and 0.03 mol of HCl,
A solution of 0 ml of an aqueous solution of C ₂ H ₅ OH whose viscosity was adjusted for one day was used. The lens blank 26 made of quartz glass is
After disposing it on the transfer mold 23 into which the hydrolysis product of alcoholate has been injected and fixing the lens blank with the clamp ring 24, the sensor 27 monitors the relative position between the barrel mold 22 and the transfer mold 23 to a desired position. Formed. At this time, irradiation was performed for 3 hours from the clamp ring 24 side using an excimer lamp having a wavelength of 146 nm as a light source. The transfer type is obtained by ultra-precise machining of a cemented carbide mainly composed of WC into a desired aspherical shape.
One formed to a thickness of nm was used. Thereafter, the transfer mold 23 and the lens blank 26 were released by a mechanism (not shown). The formed SiO ₂ layer was amorphous and had sufficient mechanical strength without any cracks or peeling off from the lens blank even after release.

Further, the sample Si produced in the same manner
When the refractive index of the O2 film was measured with an ellipsometer, the wavelength was 632.8 nm, which was 1.46, the same as that of the lens blank.
Met. Even when the produced aspheric lens was used for a KrF excimer laser optical system or an ArF excimer laser optical system, problems such as a decrease in transmittance and damage due to laser did not occur.

(Second Embodiment) The material used for forming the shape in the first embodiment was Si (OC ₂ H ₅ ) ₄ : 25 g, and 50 mol% of Al (OisoC ₃ H) with respect to Si alcoholate. ₇ ) ₃ and 1
2 mol water, 0.3 g HCl, 37.6 g C ₂ H ₅ O
A desired shape was formed on a glass (BK7) lens blank under the same conditions and using the same apparatus as in the first example, except that an aqueous solution of H whose viscosity was adjusted for 1.5 days was used. Thereafter, the transfer mold and the lens blank were released by the same mechanism as in the first embodiment. Shaped Al ₂ O ₃ -SiO
_{The two} layers were amorphous and had sufficient mechanical strength without any cracks or peeling from the lens blank even after release.

The Al sample of the sample prepared in the same manner
_When the refractive index of the ₂ O ₃ —SiO ₂ film was measured by an ellipsometer, the wavelength was 632.8 nm, which was 1.52, which is the same as that of the lens blank. Even when the produced aspheric lens was used for a lens optical system for a camera, problems such as a decrease in transmittance, cracking, and peeling did not occur. (Third embodiment) materials used for shaping in the first _{embodiment, Si (OC 2 H 5)} 4: 25g, Si alcoholate against 50 mol% of Al (OisoC ₃ H _{7) 3} And 12 moles of water,
A plastic lens blank was prepared using the same apparatus as in the first embodiment under the same conditions, except that an aqueous solution of 0.3 g of HCl and 37.6 g of C ₂ H ₅ OH was adjusted in viscosity for 1.5 days. (Zeonex-280, manufactured by Zeon Corporation)
The desired shape was formed on top. Thereafter, the transfer mold and the lens blank were released by the same mechanism as in the first embodiment. The formed Al ₂ O ₃ —SiO ₂ layer was amorphous and had sufficient mechanical strength without any cracks or peeling off from the lens blank even after release from the mold. Further, the refractive index of the Al ₂ O ₃ —SiO ₂ film of the sample produced in the same manner was measured by an ellipsometer and found to have a wavelength of 632.8 nm, which was 1.53 which is the same as that of the lens blank. Even when the produced aspheric lens was used for a lens optical system for a camera, problems such as a decrease in transmittance, cracking, and peeling did not occur.

(Fourth Embodiment) The material used for forming the shape in the first embodiment was Si (OC ₂ H ₅ ) ₄ : 25 g, and 20 mol% of Ti (OisoC ₃ H) with respect to Si alcoholate. ₇ ) ₄ and 1
5 mol water, 0.3 g HCl, 37.6 g C2 H5 O
Except that the viscosity of the aqueous solution of H was adjusted for 2 days.
Using the same apparatus as in the first example, a desired shape was formed on a glass (SK12) lens blank under the same conditions. Thereafter, the transfer mold and the lens blank were released by the same mechanism as in the first embodiment. Molded TiO ₂ -SiO ₂
The layer was amorphous and had sufficient mechanical strength without cracks or release from the flat lens blank even after release.
In addition, the Al ₂ O ₃ —SiO
_When the refractive index of the _two films was measured by an ellipsometer, the wavelength was 632.8 nm, which was 1.58, which is the same as that of the lens blank. Even when the produced aspheric lens was used for a lens optical system for a camera, problems such as a decrease in transmittance, cracking, and peeling did not occur.

It should be noted that the present invention is applicable to modifications or variations of the above embodiment without departing from the spirit thereof.

[0040]

As described above, according to the present invention,
In the case of binary optical lenses having a step-shaped cross-section or a sawtooth-shaped cross-section diffraction pattern used in optical systems such as cameras, printers, copiers, facsimiles, and optical heads for magneto-optical recording media, an energy-curable resin is used instead. 4e using a hydrolysis product of metal alcoholate
By irradiating light with energy of V or more, it can be used in the ultraviolet region without depending on the refractive index of the base material, and can use a plastic material as a lens blank because it does not use heat. Shape or
A method for manufacturing a binary optical lens having a diffraction pattern shape having a sawtooth cross section can be provided.

In an aspherical lens used in an optical system such as a camera, a printer, a copying machine, and a facsimile,
By using a hydrolysis product of metal alcoholate instead of the energy-curable resin and irradiating light with an energy of 4 eV or more, without depending on the refractive index of the base material,
It is possible to provide a method for manufacturing an aspherical composite optical element that can be used in the ultraviolet region and that can use a plastic material as a lens blank because it does not use heat.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a mold having a diffraction pattern having a sawtooth cross section. .

FIG. 2 is a side cross-sectional view showing a state where a binary optical lens having a sawtooth cross-sectional diffraction pattern shape is formed.

FIG. 3 is a side sectional view of a mold having a diffraction pattern having a step-like cross section.

FIG. 4 is a side sectional view showing a state in which a binary optical lens having a diffraction pattern shape having a stepped sectional cross section is formed.

FIG. 5 is a side view showing the structure of a mold for molding an aspheric lens.

FIG. 6 is a sectional view showing a state where an aspheric lens is formed.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 Molding die 2 Body die 3 Transfer die (diffraction pattern with sawtooth cross section) 4 Transfer die (diffraction pattern with stepwise cross section) 5 Clamp ring 6 Metal alcoholate 7 Lens blank 8 Flat lens blank 9 Position sensor 10 Metal alcoholate Oxide 114 High energy light of 4 eV or more

Claims (11)

[Claims] 1. A binary method comprising: supplying a metal alcoholate to the surface of an optical element base material; and pressing the metal alcoholate with a mold for forming an optical element to form an oxide layer having irregularities on the optical element base material. A method for manufacturing an optical element. 2. The binary optical element according to claim 1, wherein a light having an energy of 4 eV or more is irradiated when forming the oxide layer having a shape having irregularities on the optical element substrate. Manufacturing method. 3. The binary optical element according to claim 1, wherein the shape having irregularities formed on the optical element substrate is a diffraction pattern having a stepped cross section or a sawtooth cross section. Manufacturing method. 4. The method according to claim 1, wherein the optical element substrate is quartz. 5. The method according to claim 1, wherein the metal alcoholate is silicon alcoholate. 6. The method according to claim 1, wherein the metal alcoholate is a composite of two or more metal alcoholates. 7. A non-aspherical oxide layer formed by supplying a metal alcoholate to the surface of an optical element substrate and pressing the same with a mold for forming an optical element to form an oxide layer having an aspherical shape on the optical element substrate. A method for manufacturing a spherical composite optical element. 8. The aspherical composite optic according to claim 7, wherein when forming the oxide layer having an aspherical shape on the optical element substrate, light having energy of 4 eV or more is irradiated. Device manufacturing method. 9. The method according to claim 7, wherein the optical element substrate is quartz. 10. The method according to claim 7, wherein the metal alcoholate is silicon alcoholate. 11. The method according to claim 7, wherein the metal alcoholate is a composite of two or more metal alcoholates.