JP2011107509A - Optical element, and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical element having improved light resistance by providing an inorganic/organic laminated layer wherein at least a pair of inorganic/organic laminated films is laminated in the order of the inorganic layer and the organic layer on the surface of a molded part made of a resin, and to provide a method for manufacturing the optical element. <P>SOLUTION: In the optical element (objective lens) having the molded part 50 molded from a resin material, the resin material has an alicyclic hydrocarbon structure, and has at least a pair of inorganic/organic laminated films 52 formed at least in the order of the inorganic layer and the organic layer on the surface of the molded part 50. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical element and a method for manufacturing the optical element.

In an optical pickup device, the wavelength of a laser light source used as a light source for reproducing information recorded on an optical disk and recording information on the optical disk has been reduced. For example, a blue-violet semiconductor laser or a second harmonic wave is used. Laser light sources having a wavelength of 390 to 420 nm such as a blue-violet SHG laser that performs wavelength conversion of an infrared semiconductor laser using generation are being put into practical use.
On the other hand, a plastic optical element (for example, an objective lens) that can be mass-produced at low cost is used as an optical system installed in an optical pickup device. As the plastic material, a copolymer of a cyclic olefin and an α-olefin is known. In addition, an inorganic compound is laminated on the surface of a resin lens (resin molding part) using a cyclic olefin polymer by a vapor deposition method or the like as a surface coating such as an antireflection film or a hard coat. When plastic is used as the lens material, the difference in refractive index between the lens material and the film is small, so a single layer does not provide a sufficient antireflection effect, and a multilayer film of inorganic compounds is often laminated. (For example, refer to Patent Document 1).

JP 2009-176381 A

However, when a plastic optical element is used in an optical pickup device for a high-density recording medium that performs reproduction and recording using a blue light source, the resin lens heat is irradiated by irradiating short wavelength blue light for a long time. Due to deformation and alteration, there is a problem that stress is applied between the inorganic multilayer films and the interface between the resin lens and the inorganic film, and microcracks are generated in the inorganic film. The occurrence of microcracks increases the oxygen gas permeability of the surface coat film and promotes the deterioration of the resin lens. As a result, the lens characteristics are deteriorated such as aberration variation, transmittance decrease, and surface shape change.
This invention is made | formed in view of the said situation, By providing the inorganic / organic laminated film which laminated | stacked at least one pair of inorganic / organic laminated film which consists of the order of an inorganic layer-organic layer on the surface of a resin lens. An object of the present invention is to provide an optical element with improved light resistance and a method for manufacturing the optical element.

According to one aspect of the present invention, an optical element having a molded part molded from a resin material,
The resin material has an alicyclic hydrocarbon structure,
There is provided an optical element characterized in that it has at least a pair of inorganic / organic laminated films in the order of at least an inorganic layer and an organic layer on the surface of the molded part.

According to another aspect of the present invention, there is provided a method of manufacturing an optical element having a molded part molded from a resin material,
The resin material has an alicyclic hydrocarbon structure,
An inorganic / organic laminated film having at least a pair of an inorganic layer made of silicon nitride formed by vacuum vapor deposition on the surface of the molded part and an organic layer made of paraxylylenes formed by vapor deposition polymerization on the inorganic layer. A method for manufacturing an optical element is provided.

  According to the present invention, by applying an inorganic / organic laminated film composed of an inorganic layer to an organic layer on the surface of a resin molded part, the interface between the inorganic compounds generated during laser irradiation and between the molded part and the inorganic compound are formed. The stress at the interface is relaxed, and the occurrence of microcracks can be suppressed. By suppressing the occurrence of microcracks, the lens characteristics deteriorate due to the deterioration of the adhesion of the coating film applied to the surface of the molding part and the oxidation deterioration of the molding part due to the reduction of the oxygen gas barrier property of the coating film. Progress, transmittance decrease, and progress of surface shape change can be suppressed.

It is a figure which shows schematic structure of the optical pick-up apparatus which concerns on this embodiment. It is a partially expanded view of the optical element according to the present embodiment.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the optical pickup device 30 includes a semiconductor laser oscillator 32. The semiconductor laser oscillator 32 is an example of a light source, and emits blue laser light (blue-violet laser) having a specific wavelength (for example, 405 nm) of 350 to 450 nm for BD (Blu-ray Disc: registered trademark). ing. On the optical axis of the blue laser light emitted from the semiconductor laser oscillator 32, a collimator 33, a beam splitter 34, a quarter wavelength plate 35, a diaphragm 36, and an objective lens 37 are arranged in a direction away from the semiconductor laser oscillator 32. Are sequentially arranged.

A sensor lens group 38 including two sets of lenses and a sensor 39 are sequentially arranged at a position close to the beam splitter 34 and in a direction orthogonal to the optical axis of the blue-violet light described above.
The objective lens 37 is disposed at a position facing the high-density optical disk D (BD optical disk), and condenses the blue laser light emitted from the semiconductor laser oscillator 32 on one surface of the optical disk D. Yes. The objective lens 37 is an example of an optical element, and the image-side numerical aperture NA is 0.7 or more. A flange portion is formed on the periphery of the objective lens 37, and a two-dimensional actuator 40 is mounted on the flange portion. The objective lens 37 is movable on the optical axis by the operation of the two-dimensional actuator 40.

FIG. 2 is an enlarged view of a part of the objective lens 37.
As shown in FIG. 2, the objective lens 37 is mainly composed of a resin molding part 50, and a pair of inorganic / organic laminated films 52 each having an inorganic-organic order with respect to the front surface 37a and the back surface 37b. Is formed. An antireflection film 51 made of an inorganic compound is formed on the outermost surface of the inorganic / organic laminated film 52. In FIG. 2, the inorganic / organic laminated film 52 and the antireflection film 52 made of an inorganic compound are depicted only on the surface 37a. The molded part 50 is molded into a lens shape, and the front surface 37a and the back surface 37b are optical surfaces so as to exhibit essential optical functions such as a light collecting function.
In the present invention, the stress generated between the molded part 50 and the first inorganic layer is provided by providing a pair of inorganic / organic laminated films 52 in the order of inorganic-organic on the surface of the resin molded part 50. Is substantially alleviated by the second organic layer from the molded part 50. Further, the stress generated between the coating layers on the outer side of the second organic layer from the molded part 50 is also almost alleviated by the second organic layer from the molded part 50. This is presumably because the stress of the molded part 50, which is the site where the largest distortion occurs when laser irradiation is performed, is alleviated by the flexibility of the second organic layer from the molded part 50.
Here, the inorganic / organic laminated film 52 is formed in the molding part 50 so as to have an inorganic-organic order when the organic / inorganic laminated film having an organic-inorganic order is formed in the molding part 50. This is because it is not suitable due to the low adhesion of the film in the portion 50 and the first organic layer and the problem in production. For example, when an organic layer having high affinity with the molded part 50 is laminated on the molded part 50 by solvent coating, the molded part 50 is also dissolved during application and the shape changes. For example, when the organic layer is solvent-coated on the molded part 50 using a solvent in which the molded part 50 does not dissolve, the affinity between the molded part 50 and the organic layer is deteriorated. Further, for example, when an organic layer of paraxylylenes is to be laminated on the molding unit 50, the substrate is usually treated with a silane coupling agent for improving adhesion before the paraxylylenes are laminated. Since the resin has a hydrocarbon structure, the silane coupling agent cannot be bonded to the substrate. As described above, a film that can withstand laser irradiation cannot be formed on the molded part 50 by coating in the order of organic-inorganic due to deformation due to dissolution of the molded part 50 and a decrease in adhesion between the molded part 50 and the organic layer. . Therefore, it is necessary to coat the molding part 50 in the order of inorganic-organic.

<Molding part>
The molding part 50 is made of a resin material having an alicyclic hydrocarbon structure. Examples of alicyclic hydrocarbon resins include norbornene resins, monocyclic cyclo (cyclic) olefin resins, cyclo (cyclic) conjugated diene resins, vinyl alicyclic hydrocarbon resins, and hydrides thereof. Can be mentioned. Among these, norbornene-based resins can be suitably used because of their good transparency and moldability.

  Examples of the norbornene-based resin include a ring-opening polymer of a monomer having a norbornene structure, a ring-opening copolymer of a monomer having a norbornene structure and another monomer, a hydride thereof, and a norbornene structure. An addition polymer of a monomer having a monomer, an addition copolymer of a monomer having a norbornene structure and another monomer, or a hydride thereof. Among these, a ring-opening (co) polymer hydride of a monomer having a norbornene structure is particularly suitable from the viewpoints of transparency, moldability, heat resistance, low hygroscopicity, dimensional stability, lightness, and the like. Can be used.

Examples of the monomer having a norbornene structure include bicyclo [2.2.1] hept-2-ene (common name: norbornene) and tricyclo [4.3.0.1 ^2,5 ] deca-3,7-diene. (Common name: dicyclopentadiene), 7,8-benzotricyclo [4.3.0.1 ^2,5 ] dec-3-ene (common name: methanotetrahydrofluorene), tetracyclo [4.4.0. 1 ^2,5 . 1 ^7,10 ] dodec-3-ene (common name: tetracyclododecene), and derivatives of these compounds (for example, those having a substituent in the ring). Here, examples of the substituent include an alkyl group, an alkylene group, and a polar group. In addition, these substituents may be the same or different and a plurality may be bonded to the ring. Monomers having a norbornene structure can be used singly or in combination of two or more.

  Examples of the polar group include a hetero atom or an atomic group having a hetero atom. Examples of the hetero atom include an oxygen atom, a nitrogen atom, a sulfur atom, a silicon atom, and a halogen atom. Specific examples of the polar group include a carboxyl group, a carbonyloxycarbonyl group, an epoxy group, a hydroxyl group, an oxy group, an ester group, a silanol group, a silyl group, an amino group, a nitrile group, and a sulfone group.

  Other monomers capable of ring-opening copolymerization with a monomer having a norbornene structure include monocyclo (cyclic) olefins such as cyclohexene, cycloheptene, and cyclooctene and derivatives thereof, and cyclo (such as cyclohexadiene and cycloheptadiene). Cyclic) conjugated dienes and derivatives thereof.

  A ring-opening polymer of a monomer having a norbornene structure and a ring-opening copolymer of a monomer having a norbornene structure and another monomer copolymerizable with the monomer have a known ring-opening polymerization catalyst. It can be obtained by (co) polymerization in the presence.

  Examples of other monomers that can be addition copolymerized with a monomer having a norbornene structure include α-olefins having 2 to 20 carbon atoms such as ethylene, propylene, and 1-butene, and derivatives thereof; cyclobutene, cyclopentene, Cycloolefins such as cyclohexene and derivatives thereof; non-conjugated dienes such as 1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, and the like. These monomers can be used alone or in combination of two or more. Among these, α-olefin is preferable and ethylene is more preferable.

  An addition polymer of a monomer having a norbornene structure and an addition copolymer of another monomer copolymerizable with a monomer having a norbornene structure can be used in the presence of a known addition polymerization catalyst. It can be obtained by polymerization.

  A hydrogenated product of a ring-opening polymer of a monomer having a norbornene structure, a hydrogenated product of a ring-opening copolymer of a monomer having a norbornene structure and another monomer capable of ring-opening copolymerization thereof, Hydrogenated product of addition polymer of monomer having norbornene structure, and hydrogenated product of addition copolymer of monomer having norbornene structure and other monomer capable of addition copolymerization with this, A known hydrogenation catalyst containing a transition metal such as nickel or palladium is added to a solution of these polymers, and the carbon-carbon unsaturated bond is preferably hydrogenated by 90% or more.

Among norbornene-based resins, as repeating units, X: bicyclo [3.3.0] octane-2,4-diyl-ethylene structure and Y: tricyclo [4.3.0.1 ^2,5 ] decane-7 , 9-diyl-ethylene structure, the content of these repeating units is 90% by mass or more based on the entire repeating units of the norbornene resin, and the content ratio of X and the content ratio of Y The ratio of X: Y is preferably 100: 0 to 40:60.

  The molecular weight of the cyclo (cyclic) olefin resin used in this embodiment is appropriately selected according to the purpose of use. Polyisoprene or polystyrene-equivalent weight average molecular weight (Mw) measured by gel permeation chromatography using cyclohexane (toluene if the polymer resin does not dissolve) as a solvent, usually 20,000 to 150,000. . Preferably it is 25,000-100,000, More preferably, it is 30,000-80,000. When the weight average molecular weight is in such a range, the mechanical strength and molding processability of the film are highly balanced and suitable.

  The glass transition temperature of the cyclo (cyclic) olefin resin may be appropriately selected according to the purpose of use. Preferably it is 130-160 degreeC, More preferably, it is the range of 135-150 degreeC.

  Specific examples of the cycloolefin resin used in this embodiment include, for example, JSR Corporation trade name: ARTON, Nippon Zeon Corporation trade name: Zeonex, Mitsui Chemicals, Inc. trade name: Apel, Sekisui Chemical Kogyo Co., Ltd. product name: Essina etc. can be mentioned.

  The molded part 50 may contain a filler, an antioxidant, an ultraviolet absorber, a heat stabilizer, a lubricant, an antistatic agent, an antibacterial agent, a pigment, and the like. For example, by including 1 to 2 wt% of the antioxidant in the molded part 50, the light resistance can be improved while suppressing the occurrence of bleed out.

<Inorganic / organic laminated film>
(Inorganic layer)
The inorganic layer is preferably composed of a compound containing at least one element of Si, Al, Zr, Ti, Ta, Ce, Hf, La, and Ge. Of these, SiO ₂ , SiN, and ZrO ₂ are preferably used.

(Organic layer)
For the organic layer, polyparaxylylenes, alicyclic hydrocarbon resins, polymethyl methacrylate resins, polyester resins, polycarbonate resins, polydimethylsiloxanes, etc. can be used, but are not limited to the above. It is not something. Further, the resins may contain a light-resistant stabilizer such as an antioxidant, a hydrophilic stabilizer, and a UV absorber.
Here, polyparaxylylenes include polyparaxylylene (parylene N), polymonochloroparaxylylene (parylene C), polydichloroparaxylylene (parylene D), polytetrafluoroparaxylylene (parylene HT), etc. It is.

<Antireflection film>
The antireflection film 51 may have a single layer structure or a multi-layer structure. The antireflection film 51 can exhibit an antireflection function even if it has a single layer structure, but a multi-layer structure composed of two or more layers is preferable because the antireflection effect can be enhanced.
In this embodiment, at least one layer of the antireflection film 51 is an inorganic compound layer (a layer composed of an inorganic compound), and the inorganic compound layer includes Si, Al, Zr, Ti, Ta, Ce, Hf, and La. , Ge contains at least one element.

Next, a method for manufacturing the objective lens 37 will be described.
<Formation of molded part>
First, the resin having the alicyclic hydrocarbon structure is injection-molded on a mold under a certain condition to form a molded part 50 having a predetermined shape. Moreover, in order to improve light resistance, you may contain 1 to 2 wt% antioxidant in the shaping | molding part 50. FIG.

<Inorganic / organic laminated film>
The inorganic / organic laminated film 52 is formed by sequentially laminating an inorganic layer and an organic layer. Here, the lamination of the inorganic layers will be described.
(Lamination of inorganic layers)
The inorganic layer may be laminated by vacuum deposition, sputtering, CVD, plasma CVD or the like, or sol-gel method, but preferably vacuum deposition is used.
In vacuum deposition, an inorganic compound serving as a deposition source for the inorganic layer is set and film formation is performed. At this time, a gas such as oxygen is introduced into the chamber as necessary. The pressure during vapor deposition is preferably in the range of 1.0 × 10 ⁻³ Pa to 5.0 × 10 ⁻² Pa.

Next, the lamination of organic layers will be described.
(Lamination of organic layers)
The organic layer may be laminated by vacuum deposition, vapor deposition polymerization, chemical vapor deposition, or liquid phase coating such as spin coating, dip coating, spray coating, etc., but preferably by vapor deposition polymerization or spin coating. Use a coat. More preferably, vapor deposition polymerization is used.
(1) Spin coating Spin coating of an organic layer is achieved by setting an optical element to be coated on a spin coater, dropping a solution in which an organic compound to be laminated is dissolved onto the optical element, and spinning the solution. The spin coat is preferably rotated at 4000 rpm for 30 seconds or more.

(2) Vapor Deposition Polymerization This method is possible when the organic compound to be laminated is a polymer compound. The vapor deposition polymerization is a method in which a monomer or dimer of an organic compound to be laminated is vaporized in a vapor deposition source and a polymerization reaction proceeds when adsorbed on an optical element to be coated, thereby forming a film. At this time, the organic compound to be laminated may be anything as long as it can be vapor deposition polymerized, but it is preferable to use paraxylylenes. In order to increase the adhesion between the inorganic layer and the organic layer, it is preferable to perform a pretreatment with a silane coupling agent before the organic layer is laminated. In the pretreatment with the silane coupling agent, the vapor of the silane coupling agent exposes the surface of the inorganic material, whereby the silanol groups of the constituent molecules are bonded to the surface of the inorganic material. Moreover, the epoxy group and amino group at the other end of the silane coupling agent are easily bonded to the organic material, and the adhesion of the organic layer is increased. As the silane coupling agent, one having an epoxy group or an amino group is preferably used.
When laminating an organic layer of paraxylylene, it can be formed by the following treatment. First, an optical element whose surface is coated with an inorganic layer is set in a vacuum chamber, and a silane coupling agent having an epoxy group or an amino group is applied at a pressure of 1.0 × 10 ³ Pa to 1.0 at 40 ° C. to 100 ° C. Vapor deposition is performed at × 10 ⁴ Pa. Subsequently, dimer which is a raw material of the paraxylylene film was vaporized in a sublimation furnace at 150 ° C. to 165 ° C., and the vaporized diparaxylylene was pyrolyzed in a pyrolysis furnace at 690 ° C. to generate a paraxylylene radical. Paraxylylene radical was introduced into a film formation tank whose pressure was reduced to 4.3 to 4.5 × 10 ³ Pa, and the film formation time was controlled in this film formation tank to coat the inorganic layer. An organic layer made of paraxylylenes can be laminated on a certain optical element.

<Deposition of antireflection film>
An antireflection film 51 is formed on the inorganic / organic laminated film 52. This step is performed by a vapor phase method such as a vacuum evaporation method. An inorganic compound serving as a vapor deposition source of the antireflection film is set in the chamber of the vapor deposition machine, and film formation is performed on the inorganic / organic laminated film 52. At this time, a gas such as oxygen is introduced into the chamber as necessary. Further, when the antireflection film is composed of a plurality of layers, a multilayer film can be obtained by performing evaporation by sequentially changing the compound of the evaporation source. Further, the thickness can be freely changed within a range that does not cause inconvenience in light of the optical function of the target optical element and the mechanical characteristics of the corresponding film. Further, the antireflection film can be formed by other vapor phase methods such as a sputtering method, a CVD method, and a plasma CVD method in addition to the vacuum evaporation method.

Next, the operation of the optical pickup device 30 will be described with reference to FIG.
Blue laser light is emitted from the semiconductor laser oscillator 32 during an operation of recording information on the optical disc D or an operation of reproducing information recorded on the optical disc D. The emitted blue laser light passes through the collimator 33 and is collimated into infinite parallel light, then passes through the beam splitter 34 and passes through the quarter wavelength plate 35. Furthermore, after passing through the blue laser beam aperture 36 and the objective lens 37, forms a converged spot on an information recording surface D ₂ through the protective substrate D ₁ of the optical disc D.

Blue laser light that formed the concentrated light spot is modulated by the information recording surface D ₂ of the optical disk D by the information bits, is reflected by the information recording surface D _2. Then, the reflected light is sequentially transmitted through the objective lens 37 and the diaphragm 36, the polarization direction is changed by the quarter wavelength plate 35, and the reflected light is reflected by the beam splitter 34. Thereafter, the reflected light passes through the sensor lens group 38 to be given astigmatism, is received by the sensor 39, and finally is photoelectrically converted by the sensor 39 to become an electrical signal.

  Thereafter, such an operation is repeatedly performed, and the operation of recording information on the optical disc D and the operation of reproducing information recorded on the optical disc D are completed.

  As described above, at least a pair of inorganic / organic laminated film 52 composed of an inorganic layer and an organic layer on the surface of the resin-made molded part 50 having an alicyclic hydrocarbon structure, and a reflection composed of an inorganic compound thereon. By forming the prevention film 51, it is possible to relieve stress generated at the interface between the surface of the molded part 50 and the inorganic layer and between the inorganic layers. As a result, the occurrence of microcracks is suppressed, and the lens characteristics are deteriorated starting from the oxidative deterioration of the molded part 50 due to the deterioration of the film adhesion of the coat film and the oxygen gas barrier property of the coat film, that is, the progression of aberration fluctuations and the decrease of transmittance. The progress of the surface shape change can be suppressed.

Hereinafter, the present invention will be specifically described with reference to examples and comparative examples.
(Production of resin lens (molded part 50))
As a resin having an alicyclic hydrocarbon structure, tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene and ethylene copolymer were used, and 2% by weight of bis- [2,2,6,6-tetramethyl-4-piperidinyl] sebacate was added and used as HALS. An objective lens (molded part 50) having an effective diameter of 3 mm and a numerical aperture of 0.85 was produced by injection molding of the resin. Moreover, 2 wt% antioxidant Irgafos12 was contained in the molding part 50.

[Sample preparation of Example 1]
A Si ₃ N ₄ layer was laminated by vacuum deposition on the molded part 50 obtained by the above process. In this study, vacuum deposition was performed using a vacuum deposition machine ACE1150 (manufactured by Shincron). Specifically, an Si ₃ N ₄ layer having a thickness of 20 nm was stacked under a pressure of 1.0 × 10 ⁻² Pa and a film formation rate of 3 L / sec while introducing nitrogen gas.
Subsequently, a polydichloroparaxylylene layer was laminated by vapor deposition polymerization. In this study, pretreatment with a silane coupling agent and parylene vapor deposition polymerization were performed using a parylene vapor deposition apparatus Labo Coater PDS-2010 (manufactured by Japan Parylene Co., Ltd.). The optical element on which the Si ₃ N ₄ layers were laminated was set in a parylene vapor deposition apparatus, and 5 ml of aminopropyltrimethoxysilane was vapor-deposited at 80 ° C. and a pressure of 1.0 × 10 ³ Pa as a pretreatment for parylene vapor deposition. Subsequently, 5 g of dichloroparaxylylene dimer was vaporized in a sublimation furnace at 160 ° C. and 1.3 × 10 ² Pa, vaporized, and thermally decomposed at 690 ° C. and 65 Pa to generate dichloroparaxylylene radicals. Then, the generated dichloroparaxylylene radical was vapor-deposited and polymerized at 25 ° C. and 13 Pa to laminate a dichloroparaxylylene film having a thickness of 50 nm. Subsequently, an antireflection film Si ₃ N ₄ / SiO ₂ layer was laminated. Here, a vacuum vapor deposition machine ACE1150 (manufactured by Shincron) was used for vapor deposition of the antireflection film. The Si ₃ N ₄ layer stack of the antireflection film was stacked by 20 nm by the same method as the first Si ₃ N ₄ layer stack. Subsequently, 20 nm of SiO ₂ was laminated under a pressure of 1.0 × 10 ⁻³ Pa to obtain a target sample.

[Sample preparation of Example 2]
A SiO ₂ layer having a thickness of 20 nm was laminated on the molding part 50 in the same manner as in the SiO ₂ layer vacuum deposition in Example 1. Subsequently, a dichloroparaxylylene film having a thickness of 50 nm was laminated by the same method as the dichloroparaxylylene film lamination of Example 1. Subsequently, an antireflection film SiO ₂ / ZrO ₂ / SiO ₂ layer was laminated. Under a pressure of 1.0 × 10 ⁻³ Pa, SiO ₂ is 100 nm, while introducing oxygen gas, ZrO ₂ is 20 nm under a pressure of 1.0 × 10 ⁻² Pa and under a pressure of 1.0 × 10 ⁻³ Pa. ₂ was evaporated to 20 nm to obtain a target sample.

[Sample preparation of Example 3]
A Si ₃ N ₄ layer having a thickness of 20 nm was laminated on the molded part 50 in the same manner as in the Si ₃ N ₄ layer vacuum deposition of Example 1. Subsequently, a resin having an alicyclic hydrocarbon structure was laminated. Specifically, the molding part 50 in which the Si ₃ N ₄ layers are laminated is set on a spin coater, and a cyclohexane solution (10 w%) of a resin having an alicyclic hydrocarbon structure used for forming the molding part 50 is used. A resin film having an alicyclic hydrocarbon structure with a film thickness of 50 nm was laminated by dropping 10 μL and rotating at 4000 rpm for 30 seconds. Subsequently, to obtain a sample of interest by performing the lamination of the antireflective film Si ₃ N ₄ / SiO ₂ layer in the same manner as in Example 1.

[Sample preparation of Example 4]
In Example 2, a target sample was obtained by laminating a resin having an alicyclic hydrocarbon structure by the same method as in Example 3 instead of the dichloroparaxylylene film as the organic layer.

[Sample preparation of Example 5]
In Example 1, the target sample was obtained by setting the amount of the dichloroparaxylylene dimer as the raw material for the organic layer to 1 g and the film thickness of the dichloroparaxylylene layer to 10 nm.

[Sample preparation of Example 6]
In Example 2, the target sample was obtained by setting the amount of the dichloroparaxylylene dimer as the raw material for the organic layer to 1 g and the film thickness of the dichloroparaxylylene layer to 10 nm.

[Sample preparation of Example 7]
In Example 3, the concentration of the cyclohexane solution of the resin having an alicyclic hydrocarbon structure was set to 4 w% so that the film thickness of the resin layer having an alicyclic hydrocarbon structure was 10 nm to obtain a target sample. .

[Sample preparation of Example 8]
In Example 4, the target sample was obtained by setting the thickness of the resin layer having an alicyclic hydrocarbon structure to 10 nm by setting the concentration of the cyclohexane solution of the resin having the alicyclic hydrocarbon structure to 4 w%. .

[Sample preparation of Example 9]
In Example 1, the target sample was obtained by setting the amount of the dichloroparaxylylene dimer as the raw material for the organic layer to 10 g and the film thickness of the dichloroparaxylylene layer to 100 nm.

[Sample preparation of Example 10]
In Example 2, the target sample was obtained by setting the amount of the dichloroparaxylylene dimer as the raw material for the organic layer to 10 g and the film thickness of the dichloroparaxylylene layer to 100 nm.

[Sample preparation of Example 11]
In Example 3, the concentration of the cyclohexane solution of the resin having an alicyclic hydrocarbon structure was set to 15 w% so that the film thickness of the resin layer having an alicyclic hydrocarbon structure was 100 nm to obtain a target sample. .

[Sample preparation of Example 12]
In Example 4, the target sample was obtained with the film thickness of the resin layer having the alicyclic hydrocarbon structure being 100 nm by setting the concentration of the cyclohexane solution of the resin having the alicyclic hydrocarbon structure to 15 w%. .

[Sample preparation of Example 13]
In Example 1, the target sample was obtained by setting the film thickness of the dichloroparaxylylene layer to 5 nm with a charge of 0.5 g of dichloroparaxylylene dimer as a raw material for the organic layer.

[Sample preparation of Example 14]
In Example 2, a target sample was obtained by setting the amount of the dichloroparaxylylene dimer, which is a raw material of the organic layer, to 0.5 g and setting the thickness of the dichloroparaxylylene layer to 5 nm.

[Sample preparation of Example 15]
In Example 3, the target sample was obtained by setting the film thickness of the resin layer having an alicyclic hydrocarbon structure to 10 nm by setting the concentration of the cyclohexane solution of the resin having the alicyclic hydrocarbon structure to 1 w%. .

[Sample preparation of Example 16]
In Example 4, the target sample was obtained by setting the film thickness of the resin layer having an alicyclic hydrocarbon structure to 10 nm by setting the concentration of the cyclohexane solution of the resin having an alicyclic hydrocarbon structure to 1 w%. .

[Sample preparation of Example 17]
In Example 1, the target sample was obtained by setting the amount of the dichloroparaxylylene dimer as the raw material for the organic layer to 20 g and the film thickness of the dichloroparaxylylene layer to 200 nm.

[Sample preparation of Example 18]
In Example 2, the target sample was obtained by setting the amount of the dichloroparaxylylene dimer as the raw material for the organic layer to 20 g and the film thickness of the dichloroparaxylylene layer to 200 nm.

[Sample preparation of Example 19]
In Example 3, the target sample was obtained by setting the thickness of the resin layer having an alicyclic hydrocarbon structure to 200 nm by setting the concentration of the cyclohexane solution of the resin having an alicyclic hydrocarbon structure to 20 w%. .

[Sample preparation of Example 20]
In Example 4, the target sample was obtained by setting the thickness of the resin layer having an alicyclic hydrocarbon structure to 200 nm by setting the concentration of the cyclohexane solution of the resin having the alicyclic hydrocarbon structure to 20 w%. .

[Sample preparation of Comparative Example 1]
In Example 1, the target sample was obtained by laminating only the antireflection film Si ₃ N ₄ / SiO ₂ layer.

[Sample preparation of Comparative Example 2]
In Example 1, the target sample was obtained by laminating only the antireflection film SiO ₂ / ZrO ₂ / SiO ₂ layer.

[Sample Preparation of Comparative Example 3]
In Example 1, the target sample was obtained by not performing the first Si ₃ N ₄ layer deposition.

[Sample Preparation of Comparative Example 4]
In Example 2, a target sample was obtained by not performing the first SiO ₂ layer deposition.

[Sample preparation of Comparative Example 5]
In Example 3, the target sample was obtained by not performing the first Si ₃ N ₄ layer deposition.

[Sample Preparation of Comparative Example 6]
In Example 4, the target sample was obtained by not performing the first SiO ₂ layer deposition.

[Sample Preparation of Comparative Example 7]
A target sample was obtained by laminating 50 nm of polydichloroparaxylylene on the molded part 50 in the same manner as in Example 1.

[Sample Preparation of Comparative Example 8]
A target sample was obtained by laminating 50 nm of polydichloroparaxylylene on the molded part 50 in the same manner as in the example.

(Evaluation)
Then, the evaluation method of each said sample is demonstrated.
(1) Measurement of film thickness of organic layer The film thickness of the organic layer was determined using the reflectance measurement of the sample film formation surface and the refractive index of the obtained reflectance spectrum and the film thickness correlation simulation calculation software. USPM-RU III (manufactured by Olympus) was used for the reflectance measurement, and TFCalc 3.5.6 (manufactured by Software Spectra) was used as the simulation calculation software.

(2) Evaluation of microcracks The occurrence of microcracks was evaluated by observation with a confocal laser microscope (LEXT OLS3500, manufactured by Olympus). Specifically, it was evaluated whether or not microcracks having a size of 0.1 μm or more were generated in the laser irradiation portion of the sample after laser irradiation.

(3) Evaluation of Aberration As for the aberration, the fluctuation of spherical aberration (ΔSA) was measured with an interferometer when each sample was irradiated with a laser beam of 35 mW and 405 nm at 75 ° C. for 500 hours. The measurement results are shown in Table 1. In Table 1, the evaluation criteria for ΔSA were as follows.
<< Spherical aberration fluctuation (ΔSA) >>
No change before and after laser irradiation → ◎
A change of 5 mλ or less occurred before and after laser treatment → ○
A change greater than 5 mλ and less than 10 mλ before and after the laser treatment occurred.
Change larger than 10 mλ before and after laser irradiation → ×

(4) Evaluation of white turbidity The white turbidity of each sample was evaluated by the transmittance of an area of 1 mm in the center of the lens when irradiated with laser light of 35 mW and 405 nm at 75 ° C. for 500 hours. Specifically, it evaluated by measuring the transmittance | permeability in 405 nm of a sample with the spectrophotometer U-4100 (made by Hitachi High-Tech). The results are shown in Table 1. In Table 1, the evaluation standards for cloudiness are as follows.
<Evaluation of cloudiness>
Transmittance measured when transmitting laser light of 35 mW, 405 nm at 75 ℃> 98%
Transmittance is 96% or more and less than 98%
Transmittance is 94% or more and less than 96% → △
Transmittance is less than 94% → ×

(5) Evaluation of surface shape The surface shape of each sample was evaluated by the surface shape change in the area of the center φ1 mm of the lens when irradiated with laser light of 35 mW, 405 nm at 75 ° C. for 500 hours. Specifically, the surface shape change was measured using a three-dimensional optical interference roughness meter (WYKO NT9800, manufactured by Veeco). The measurement results are shown in Table 1. In Table 1, the evaluation criteria for the surface shape change were as follows.
<< Surface shape evaluation >>
Surface shape measurement when transmitting laser light of 35 mW, 405 nm at 75 ° C. Change less than 0.005 μm before and after laser treatment → ◎
There was a change greater than 0.005μm and less than 0.008μm before and after laser treatment → ○
A change greater than 0.008μm and less than 0.010μm occurred before and after laser treatment → △
Change larger than 0.010mλ before and after laser irradiation → ×

(Summary)
As described above, in the objective lens 37 having at least a pair of inorganic / organic laminated films having the order of inorganic layer-organic layer on the surface of the molded part 50 as in Example 1 to Example 20, the laser irradiation is performed. The generated stress was alleviated and the generation of microcracks was suppressed. Further, good results were obtained with respect to light resistance such as surface shape change, aberration fluctuation ΔSA and cloudiness.
Further, in the case of a sample in which polydichloroparaxylylene is laminated in a film thickness range of 10 nm to 100 nm by vapor deposition polymerization as an organic layer, and a film containing Si ₃ N ₄ is laminated in an inorganic layer (Examples 1, 5, and 9) ), Higher light resistance was seen. This is considered to be due to the contribution of the effect of polydichloroparaxylylene and Si ₃ N ₄ having high water vapor and oxygen gas barrier properties in addition to the stress relaxation effect by the organic layer.

From the above, in the objective lens 37 having at least a pair of inorganic / organic laminated film 52 composed of the order of inorganic layer-organic layer on the surface of the molded part 50, the stress generated during laser irradiation is alleviated, and microcracks It can be considered that high light resistance has been realized because surface degradation due to water and intrusion of water vapor and oxygen gas through microcracks could be suppressed.
On the other hand, in Comparative Example 1 and Comparative Example 2 in which the inorganic / organic laminated film was not introduced, generation of microcracks was observed. For this reason, invasion of water vapor or oxygen gas into the resin could not be suppressed, resulting in poor light resistance.
In Comparative Example 3 and Comparative Example 4 in which an organic / inorganic laminated film was introduced in the order of organic-inorganic layer on the surface of the molded part 50 as an organic layer of polydichloroparaxylylene, the molded part 50 and polydichloroparaxylylene were used. The film adhesion at the interface of the layers was poor, and microcracks occurred immediately after laser irradiation. For this reason, invasion of water vapor or oxygen gas into the resin could not be suppressed, resulting in poor light resistance.
Further, in Comparative Example 5 and Comparative Example 6 in which an organic / inorganic laminated film was introduced in the order of organic-inorganic layer as a resin having an alicyclic hydrocarbon structure on the surface of the molded part 50, When a resin solution having a cyclic hydrocarbon structure was coated, partial dissolution of the surface of the molded part 50 occurred, and the surface shape after coating was distorted. For this reason, the adhesiveness of the inorganic film laminated | stacked on the organic layer fell, and the micro crack occurred immediately after laser irradiation. For this reason, invasion of water vapor or oxygen gas into the resin could not be suppressed, resulting in poor light resistance.
Further, in Comparative Example 7 in which only the organic layer polydichloroparaxylylene was introduced on the surface of the molded part 50, the film adhesion at the interface between the molded part 50 and the polydichloroparaxylylene layer was poor, and the microcracks immediately after laser irradiation. Happened. For this reason, invasion of water vapor or oxygen gas into the resin could not be suppressed, resulting in poor light resistance.
Further, in Comparative Example 8 in which only the resin having the alicyclic hydrocarbon structure of the organic layer was introduced on the surface of the molding part 50, the molding part 50 was molded when the resin solution having the alicyclic hydrocarbon structure was coated. Partial dissolution of the surface of the portion 50 occurred, and the surface shape after coating was distorted. For this reason, the stress of the whole molding part 50 became large, and the micro crack occurred immediately after laser irradiation. For this reason, invasion of water vapor or oxygen gas into the resin could not be suppressed, resulting in poor light resistance.
Note that, even if not mentioned as an example, the objective lens 37 having at least a pair of inorganic / organic laminated films 52 in the order of inorganic layer-organic layer on the surface of the molded part 50 is implemented from Example 1. As in Example 6, good results were obtained.

DESCRIPTION OF SYMBOLS 30 Optical pick-up apparatus 32 Semiconductor laser oscillator 33 Collimator 34 Beam splitter 35 1/4 wavelength plate 36 Aperture 37 Objective lens (optical element)
37a Front 37b Back 38 Sensor lens group 39 Sensor 40 Two-dimensional actuator 50 Molding part 51 Antireflection film 52 Inorganic / organic laminated film D Optical disk D ₁ Protective substrate D ₂ Information recording surface

Claims (6)

An optical element having a molded part molded from a resin material,
The resin material has an alicyclic hydrocarbon structure,
An optical element comprising at least a pair of inorganic / organic laminated films composed of at least an inorganic layer and an organic layer on the surface of the molded part.   The optical element according to claim 1, further comprising an inorganic layer having an antireflection function at the outermost part.   The optical element according to claim 1, wherein the organic layer has a thickness of 10 nm to 100 nm.   The optical element according to claim 1, wherein the inorganic layer constituting the inorganic / organic laminated film includes silicon nitride formed by vapor deposition.   5. The optical element according to claim 1, wherein the organic layer constituting the inorganic / organic laminated film has paraxylylenes formed by vapor deposition polymerization. A method for producing an optical element having a molded part molded from a resin material,
The resin material has an alicyclic hydrocarbon structure,
An inorganic / organic laminated film having at least a pair of an inorganic layer made of silicon nitride formed by vacuum vapor deposition on the surface of the molded part and an organic layer made of paraxylylenes formed by vapor deposition polymerization on the inorganic layer. An optical element manufacturing method comprising: providing an optical element.

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