WO2010074066A1

WO2010074066A1 - Optical element, optical pick-up device, and method of manufacturing optical element

Info

Publication number: WO2010074066A1
Application number: PCT/JP2009/071300
Authority: WO
Inventors: 大輔渡邉
Original assignee: コニカミノルタオプト株式会社
Priority date: 2008-12-26
Filing date: 2009-12-22
Publication date: 2010-07-01

Abstract

An optical element capable of suppressing reduction in light resistance and bleed-out of light stabilizers caused from exposure to 380 nm to 420 nm laser light. 　The optical element is used in an optical pick-up device employing a light source firing a 380 nm to 420 nm laser light beam, and is provided with a shaped part (50) comprised of alicyclic olefin resin, and a light stabilizer layer (55) formed on the surface of the shaped part (50).

Description

OPTICAL ELEMENT, OPTICAL PICKUP DEVICE, AND OPTICAL ELEMENT MANUFACTURING METHOD

The present invention relates to an optical element, an optical pickup device, and an optical element manufacturing method.

Information devices such as a player, a recorder, and a drive for reading and recording information on an optical information recording medium such as MO, CD, and DVD are provided with an optical pickup device. The optical pickup device includes an optical element unit that irradiates a medium with light having a predetermined wavelength emitted from a light source, and receives the reflected light with a light receiving element. The optical element unit receives the light from a reflection layer or a light receiving medium of the medium. An optical element such as a lens for condensing light by the element is included. In addition, in recent years, a new optical information recording medium called Blu-ray Disc (BD) has been developed that performs recording and playback using a blue laser light source (wavelength of about 380 nm to 420 nm) that has a larger recording capacity than conventional DVDs and CDs. Has been.

On the other hand, it is preferable to apply plastic as a material rather than inorganic glass in that the optical element of the optical pickup device can be manufactured at low cost by means such as injection molding. However, in an optical pickup device used for recording and reproducing BD using a blue laser, a new problem arises in that a resin optical element deteriorates due to laser light due to a shorter wavelength than a conventional light source. did. As a plastic having relatively high light resistance to blue laser light, a copolymer of cyclic olefin and α-olefin (for example, Patent Document 1) is known. However, in an optical pickup device using a blue laser beam, when a compatibility with other types of optical information recording media such as a CD or a DVD is given, or when a Blu-ray disc is used for recording, a blue laser is used. There is a need to increase the laser power of light, and even when the above-described alicyclic olefin is used, problems such as white turbidity and deformation may occur, and improvement has been demanded.

JP 2002-105131 A (page 4)

Incidentally, in the case of forming an optical element from an alicyclic olefin resin, it is known that a light stabilizer is mixed (added) to the resin itself as a means for further improving the light resistance. However, when the amount of light stabilizer added is increased in order to obtain sufficient light resistance, the transmittance decreases due to non-uniform bleeding of the light stabilizer called bleed-out, and this also causes aberrations. It can be a cause.

Therefore, a main object of the present invention is to provide an optical element, an optical pickup device, and an optical element manufacturing method capable of suppressing a decrease in light resistance due to irradiation with blue laser light without causing a light-resistant stabilizer bleed out. It is to provide.

According to one aspect of the invention,
An optical element used in an optical pickup device using a light source that emits laser light having a wavelength of 380 nm to 420 nm,
A molded part composed of an alicyclic olefin resin;
A light-resistant stabilizer layer formed on the surface of the molded part;
An optical element is provided.

According to another aspect of the invention,
In an optical pickup device using the optical element as an objective lens,
A light source that emits laser light having a wavelength of 380 nm to 420 nm;
The objective lens receiving the laser beam;
An optical pickup device is provided.

According to another aspect of the invention,
A method of manufacturing an optical element used in an optical pickup device having a light source that emits laser light having a wavelength of 380 nm to 420 nm,
Forming a molded part by molding an alicyclic olefin resin;
Forming a light-resistant stabilizer layer on the surface of the molded part;
A method for manufacturing an optical element is provided.

According to the study by the present inventors, the deterioration of the optical element due to the blue laser beam is particularly caused at the interface between the molding part and the air layer as the base material of the optical element or the interface between the molding part and the functional layer such as the antireflection layer. It occurred remarkably and it became clear that the problem was small inside the molded part. Therefore, according to the present invention, by forming a light-resistant stabilizer layer on the surface of the molded part, it becomes possible to localize the light-resistant stabilizer on the surface of the molded part, and even when irradiated with laser light, It is possible to suppress the deterioration of the resin on the surface of the molded part, which is particularly problematic.

It is drawing which shows schematic structure of the optical pick-up apparatus concerning preferable embodiment of this invention. FIG. 5 is a schematic enlarged cross-sectional view showing a modification of the surface of the molded part in a preferred embodiment of the present invention, particularly showing a state in which a concave portion is formed on the surface of the molded part and a light-resistant stabilizer layer is filled. . It is a schematic expanded sectional view which shows the modification of the surface of the shaping | molding part in preferable embodiment of this invention, Comprising: It is drawing which shows the example which formed the antireflection film especially.

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 is provided with 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) having a wavelength of 380 to 420 nm for BD (Blu-ray Disc). 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 and a sensor 39 made up of two sets of lenses are sequentially arranged in a direction close to the beam splitter 34 and perpendicular 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 disc D (BD optical disc), and condenses the blue laser light emitted from the semiconductor laser oscillator 32 on one surface of the optical disc D. Yes. The objective lens 37 has an image-side numerical aperture NA of 0.7 or more. The objective lens 37 is an example of an optical element, and the objective lens 37 is provided with a two-dimensional actuator 40. By the operation of the two-dimensional actuator 40, the objective lens 37 is movable on the optical axis.

As shown in the enlarged view of FIG. 1, the objective lens 37 is mainly composed of a molded part 50, and a light-resistant stabilizer layer 55 is formed on the surface 37a. The molding part 50 is molded into a lens shape and exhibits essential optical functions such as a light collecting function.

An alicyclic olefin resin is used for the molding part 50.

Specifically, as alicyclic olefin resin, ZEON: ZEONEX, Mitsui Chemicals: APEL, JSR: Arton, Chicona: TOPAS, etc. are preferably used.

The light-resistant stabilizer layer 55 is a layer containing a light-resistant stabilizer and is a layer having a higher amount of light-resistant stabilizer than the molded part 50. Although it does not specifically limit as a manufacturing method, For example, the layer formed by dipping a shaping | molding part in the solution which dissolved polymer matrix resin etc. containing a light-resistant stabilizer or a light-resistant stabilizer in solvents, such as water, and dried. It is. The layer thickness of the light-resistant stabilizer layer 55 is preferably 10 to 100 μm.

The ratio of the polymer matrix resin is not particularly limited, but the ratio of the light stabilizer to the polymer matrix resin is preferably 0.1% by mass to 30% by mass. If the content of the light-resistant stabilizer is small, the effect is low. On the other hand, if the amount is too large, the binder layer cannot be retained and is crumbly. A more preferable content is 5% by mass to 10% by mass.

As the polymer used together with the light-resistant stabilizer, a resin similar to a molded product, a photocurable resin composition, or various binder resins can be used.

In the present invention, it is preferable to use a high-molecular-weight light-resistant stabilizer made of a polycondensate or a polymer that itself has a film-forming ability for the light-resistant stabilizer layer. In particular, without using a polymer matrix resin, a light-resistant stabilizer layer can be formed on the surface of the molded part by dipping in a solution in which a high-molecular weight light-resistant stabilizer comprising a polycondensate or a polymer is dissolved and drying.

Examples of the light-resistant stabilizer constituting the light-resistant stabilizer layer 55 include a benzophenone-based light-resistant stabilizer, a benzotriazole-based light-resistant stabilizer, a hindered amine-based light-resistant stabilizer, and the like. From the viewpoint of colorability and the like, it is preferable to use a hindered amine light resistance stabilizer (HALS).

HALS includes N, N ′, N ″, N ′ ″-tetrakis- [4,6-bis- {butyl- (N-methyl-2,2,6,6-tetramethylpiperidin-4-yl) amino } -Triazin-2-yl] -4,7-diazadecane-1,10-diamine, dibutylamine and 1,3,5-triazine, N, N'-bis (2,2,6,6-tetramethyl Polycondensate with -4-piperidyl) butylamine, poly [{(1,1,3,3-tetramethylbutyl) amino-1,3,5-triazine-2,4-diyl} {(2,2, 6,6-tetramethyl-4-piperidyl) imino} hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl) imino}], 1,6-hexanediamine-N, N′-bis ( 2,2,6,6-tetramethyl-4-piperidyl And a polycondensate of morpholine-2,4,6-trichloro-1,3,5-triazine, poly [(6-morpholino-s-triazine-2,4-diyl) (2,2,6, High molecular weight HALS in which a plurality of piperidine rings such as 6-tetramethyl-4-piperidyl) imino] -hexamethylene [(2,2,6,6-tetramethyl-4-piperidyl) imino] are bonded via a lyazine skeleton; Polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol, 1,2,3,4-butanetetracarboxylic acid and 1,2,2,6, Mixed esterified product of 6-pentamethyl-4-piperidinol and 3,9-bis (2-hydroxy-1,1-dimethylethyl) -2,4,8,10-tetraoxaspiro [5,5] undecane Of piperidine ring is bonded to a high molecular weight HALS, and the like via an ester bond. Of these, water-soluble HALS is preferably used from the viewpoint of easily forming the light-resistant stabilizer layer 55.

In addition, you may add and mix a light-resistant stabilizer also in resin of the shaping | molding part 50. FIG. In this case, the addition amount of the light-resistant stabilizer is preferably 1.5% by mass or less, more preferably 1.0% by mass or less, based on the total amount including the resin and the light-resistant stabilizer. As the light-resistant stabilizer added to the resin, the same light-resistant stabilizer that constitutes the light-resistant stabilizer layer 55 can be used.

Further, the light-resistant stabilizer added to the resin of the molded part is not limited to the polycondensate or high molecular weight type, but also has a molecular weight of 1,000, such as trade names ADK STAB LA52, LA57, LA62, LA67 manufactured by ADEKA, for example. Less than low molecular weight compounds can be used.

As shown in FIG. 2, the light-resistant stabilizer layer 55 may be formed on the surface 37a of the molded part 50 by intentionally forming a large number of recesses 52 in the molded part 50 and filling the light-resistant stabilizer layer 55.

In this case, the recess 52 preferably has a diameter of 100 nm or less and a depth of 1 μm or less.

As shown in FIG. 3, in the objective lens 37, an antireflection film 60 may be formed on the light-resistant stabilizer layer 55.

The antireflection film 60 may be a single layer or a plurality of layers, but a structure having two or more layers is preferable in order to enhance the antireflection effect. In that case, after providing the light-resistant stabilizer layer 55 with respect to the shaping | molding part 50, the 1st layer 61 is formed and the 2nd layer 62 is formed on it.

In the present embodiment, the first layer 61 is a layer made of a high refractive index material having a refractive index of 1.7 or more, preferably Ta ₂ O ₅ , a mixture of Ta ₂ O ₅ and TiO ₂ , ZrO _2. , ZrO ₂ and a mixture of TiO ₂ . The first layer 61 may be composed of TiO ₂ , Nb ₂ O ₃ , and HfO ₂ .

The second layer 62 is a layer made of a low refractive index material having a refractive index of less than 1.7, and is preferably made of SiO ₂ and MgF ₂ .

In the objective lens 37, the first layer 61 and the second layer 62 may be alternately stacked on the first layer 61 and the second layer 62, and the antireflection film 60 may have a 2-7 layer structure as a whole. In this case, the layer that is in direct contact with the molded part 50 may be a high refractive index material layer (first layer 61) or a low refractive index material layer (second layer) depending on the type of the molded part 50. The layer 62) may be used. Here, the layer that is in direct contact with the molded part 50 is a layer of a high refractive index material.

In the objective lens 37, the light-resistant stabilizer layer 55, the concave portion 52, and the antireflection film are formed on the back surface 37b in the same manner as the light-resistant stabilizer layer 55, the concave portion 52, and the antireflection film 60 are formed on the front surface 37a. 60 may be formed.

Subsequently, a method for manufacturing the objective lens 37 will be described.

First, the thermoplastic resin is injection-molded into a mold under a certain condition to form a molded part 50 having a predetermined shape.

Thereafter, a light-resistant stabilizer layer 55 is formed on the surface 37a of the molded part 50.

As a method for forming the light-resistant stabilizer layer 55, the molded part 50 was dipped (immersed) at a constant temperature for a fixed time in a solution (aqueous solution) in which the light-resistant stabilizer was dissolved in a solvent such as water, and adhered to the molded part 50. There are a method of drying the aqueous solution, a method of applying the aqueous solution to the surface 37a of the molded part 50 and drying it, and repeating this multiple times.

As shown in FIG. 2, when forming the recessed part 52 in the shaping | molding part 50, the convex part corresponding to the recessed part 52 is formed with respect to the metal mold | die (cavity) used when forming the shaping | molding part 50, The said metal mold | die There is a method of molding a resin by using, for example.

In this case, when filling the recessed portion 52 with the light-resistant stabilizer layer 55, the light-resistant stabilizer layer 55 is formed on the molded portion 50 as described above (dip into an aqueous solution containing the light-resistant stabilizer, application of the aqueous solution, For example, a method of washing the molded part 50 with water.

As shown in FIG. 3, when the antireflection film 60 is formed on the light-resistant stabilizer layer 55, after forming the light-resistant stabilizer layer 55 by the above-described method, first, a vapor deposition source that constitutes the first layer 61 is used. Thus, the first layer 61 is formed. For example, when a (Ta ₂ O ₅ + 5% TiO ₂ ) film is formed as the first layer 61, OA600 manufactured by OPTRAN can be used as the evaporation source and the evaporation source may be evaporated by electron gun heating. During vapor deposition, it is preferable to form a film while introducing O ₂ gas up to a pressure of 1.0 × 10 ⁻² Pa inside the vacuum vapor deposition apparatus and controlling the vapor deposition rate at 5 Å / sec. Then, the film forming temperature (temperature in the vapor deposition apparatus) is maintained within an appropriate temperature range.

Thereafter, the second layer 62 is formed on the first layer 61 using the vapor deposition source constituting the second layer 62. For example, when a SiO ₂ film is formed as the second layer 62, O ₂ gas is introduced up to a pressure of 1.0 × 10 ⁻² Pa inside the vacuum vapor deposition apparatus, and the vapor deposition rate is controlled to 5 liters / sec. It is better to form the film while doing so. Then, the film forming temperature (temperature in the vapor deposition apparatus) is maintained within an appropriate temperature range.

The objective lens 37 is manufactured through the above steps.

Subsequently, the operation of the optical pickup device 30 will be described.

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.

According to the present embodiment described above, in the objective lens 37, the light-resistant stabilizer layer 55 is formed on the molded portion 50 and the light-resistant stabilizer is localized on the surface 37a. Even when irradiated with a blue laser beam having a high energy density at a wavelength, it is possible to suppress the optical performance from being deteriorated due to white turbidity or a shape change of the resin itself.

(1) Sample preparation (1.1) Sample 1
100 parts by mass of a random copolymer of ethylene and bicyclo [2,2,1] hept-2-ene and 0.5 parts by mass of pentaerythritol distearate as a surfactant are mixed to give resin 1. Obtained.

Thereafter, resin 1 was molded into a 3 mm thick plate using a fixed mold.

Thereafter, the plate was dipped (immersed) in water-soluble HALS (TAC Sun Block 77, manufactured by Okuno Pharmaceutical Co., Ltd.) at room temperature for 24 hours to localize HALS on the surface of the plate. Thereafter, the plate was removed from the solution to dry the water-soluble HALS, and a HALS layer was formed on the surface of the plate.

The resulting plate was designated as “Sample 1”.

When the layer thickness of the HALS layer formed on the surface of Sample 1 was measured, it was about 10 μm.
(1.2) Sample 2
Instead of the mold used when preparing Sample 1, a mold having a protrusion (convex portion) with a diameter of 100 nm and a depth of 1 μm is used so that a fine hole is formed on the surface of the molded plate. Then, a plate having a thickness of 3 mm was formed from the resin 1.

Then, the plate was dipped in water-soluble HALS at room temperature for 24 hours. Thereafter, the surface portion of the plate was washed with water and dried, and a HALS layer was formed on the surface of the plate (the HALS layer was filled in the concave portion of the plate).

The resulting plate was designated as “Sample 2”.
(1.3) Sample 3
As in the case of Sample 1, a 3 mm thick plate was formed from the resin 1, and then a HALS layer was formed.

Thereafter, two layers of antireflection films (AR coating) were formed on the surface of the plate on which the HALS layer was formed.

Specifically, the plate is mounted in the vacuum deposition apparatus, the pressure in the apparatus is reduced to 2 × 10 ⁻³ Pa, and the plate is heated to a predetermined temperature (about 240 ° C.) by the heater above the vacuum deposition apparatus. Heated.

Thereafter, a 20 nm (Ta ₂ O ₅ + 5% TiO ₂ ) film was formed directly on the surface of the plate as the first layer film. Specifically, OA600 manufactured by Optran Co. was used as the evaporation source, and the evaporation source was evaporated by electron gun heating to form a (Ta ₂ O ₅ + 5% TiO ₂ ) film. During the vapor deposition, the O ₂ gas was introduced until the pressure inside the vacuum vapor deposition apparatus reached 1.0 × 10 ⁻² Pa, and the film was formed while controlling the vapor deposition rate at 5 liters / sec.

Thereafter, as the second layer film, a 110 nm SiO ₂ film was formed following the first layer film. Also in this case, the film was formed while O ₂ gas was introduced until the pressure inside the vacuum deposition apparatus was 1.0 × 10 ⁻² Pa and the deposition rate was controlled at 5 Å / sec.

The plate thus obtained was designated as “Sample 3”.
(1.4) Sample 4
Similar to the case of producing Sample 1, a plate having a thickness of 3 mm was formed from Resin 1.

Then, application | coating and drying of water-soluble HALS (Okuno Pharmaceutical Co., Ltd. make, TAC sun block 77) were repeated with respect to the plate several times.

The resulting plate was designated as “Sample 4”.

When the layer thickness of the HALS layer formed on the surface of Sample 4 was measured, it was about 100 μm.
(1.5) Sample 5
1% by mass of LA-52 (ADEKA light resistance stabilizer) was added to Resin 1, and a 3 mm thick plate was molded in the same manner as Sample 1 was prepared from the resin.

Thereafter, application and drying of the water-soluble HALS aqueous solution to the plate were repeated a plurality of times.

The plate thus obtained was designated as “Sample 5”.

When the thickness of the HALS layer formed on the surface of Sample 5 was measured, it was about 10 μm.
(1.6) Sample 6
In the same manner as when Sample 2 was prepared from resin by adding 1 mass% of LA-52 (ADEKA light resistance stabilizer) to Resin 1, the diameter φ100 nm so that fine holes were formed on the plate surface after molding. , A plate having a thickness of 1 μm was produced and used to form a 3 mm thick plate.

Then, the HALS layer was formed on the surface of the plate by repeatedly applying and drying a water-soluble HALS aqueous solution to the plate a plurality of times (filling the HALS layer in the concave portion of the plate).

The plate thus obtained was designated as “Sample 6”.
(1.7) Sample 7
0.5% by mass of LA-52 was added to Resin 1, and a 3 mm thick plate was formed in the same manner as Sample 1 was prepared from the resin.

The plate thus obtained was designated as “Sample 7”.
(1.8) Sample 8
A plate having a thickness of 3 mm was formed by adding 1.0% by mass of LA-52 to Resin 1 and preparing Sample 1 from the resin.

The plate thus obtained was designated as “Sample 8”.
(1.9) Sample 9
A plate having a thickness of 3 mm was formed by adding 1.0% by mass of LA-52 to the resin 1 and preparing Sample 1 from the resin.

Thereafter, a two-layer AR coat was formed on the surface of the plate. The AR coat was formed in the same manner as when Sample 3 was produced.

The plate thus obtained was designated as “Sample 9”.
(1.10) Sample 10
1.5% by mass of LA-52 was added to Resin 1, and a 3 mm thick plate was formed in the same manner as Sample 1 was produced from the resin.

The plate thus obtained was designated as “Sample 10”.
(1.11) Sample 11
Charge 300 parts by mass of dehydrated cyclohexane, 60 parts by mass of styrene and 0.38 parts by mass of dibutyl ether, and add 0.36 parts by mass of n-butyllithium solution (15% hexane solution) while stirring at 60 ° C. The polymerization reaction was started. After carrying out the polymerization reaction for 1 hour, 8 parts by mass of styrene, 12 parts by mass of isoprene, and 0.8 parts by mass of 1,2,2,6,6-pentamethyl-4-piperidylmethacrylate were added to the reaction solution. After adding a mixed monomer consisting of 1 and carrying out a polymerization reaction for 1 hour, 0.2 parts by mass of isopropyl alcohol was added to the reaction solution to stop the reaction.

Next, 300 parts by mass of the polymerization reaction solution was transferred to a pressure resistant reactor, and 10 parts by mass of a silica-alumina supported nickel catalyst (manufactured by JGC Kagaku Kogyo Co., Ltd .: E22U, nickel supported type 60%) was used as a hydrogenation catalyst. Added and mixed. The inside of the reactor was replaced with hydrogen gas, hydrogen was further supplied while stirring the solution, the temperature was set to 160 ° C., and a hydrogenation reaction was performed at a pressure of 4.5 MPa for 8 hours.

After completion of the reaction, the reaction solution was filtered to remove the hydrogenation catalyst, 800 parts by mass of cyclohexane was added for dilution, and then the reaction solution was poured into 3500 parts by mass of isopropanol to precipitate a copolymer.

Next, this copolymer was filtered out and dried under reduced pressure at 80 ° C. for 48 hours to obtain Resin 2.

Thereafter, a plate having a thickness of 3 mm was formed from the resin 2 in the same manner as when the sample 1 was produced.

Thereafter, application and drying of water-soluble HALS to the plate were repeated several times.

The plate thus obtained was designated as “Sample 11”.

When the layer thickness of the HALS layer formed on the surface of the sample 11 was measured, it was about 10 μm.
(1.12) Sample 12
Instead of the mold used when preparing Sample 1, a mold having a protrusion (convex portion) with a diameter of 100 nm and a depth of 1 μm is used so that a fine hole is formed on the surface of the molded plate. Then, a plate having a thickness of 3 mm was formed from the resin 2.

The plate thus obtained was designated as “Sample 12”.
(1.13) Sample 13
Add 0.5% by mass of LA-52 to Resin 2 and use a mold with protrusions (convex parts) with a depth of 1 μm in the same manner as when Sample 12 was made from the resin to form a 3 mm thick plate. Formed.

The plate thus obtained was designated as “Sample 13”.
(1.14) Sample 14
0.5% by mass of LA-52 was added to Resin 2, and a 3 mm thick plate was formed in the same manner as Sample 1 was produced from the resin.

The plate thus obtained was designated as “Sample 14”.
(1.15) Sample 15
0.5% by mass of LA-52 was added to Resin 2, and a 3 mm thick plate was formed in the same manner as Sample 1 was produced from the resin.

The plate thus obtained was designated as “Sample 15”.
(2) Evaluation of sample About each sample, the initial transmittance (%) with respect to the light of wavelength 405nm was measured. U4100 manufactured by Hitachi, Ltd. was used as a measuring device. The measurement results are shown in Table 1.

Thereafter, each sample was irradiated with a 30 mW laser (wavelength 405 nm) at 70 ° C. for 3000 hours, the deterioration state after laser irradiation was observed, and the light resistance of each sample was evaluated. The observation results are shown in Table 1. In Table 1, the criteria for ◎, ○, Δ, and × showing the observation results are as follows.

“◎”… No change at all “○”… Slight turbidity is observed, but there is no problem in performance “△”… White turbidity is observed and the transmittance is reduced “×”… White turbidity is observed In addition to the reduced transmittance, the shape change is also severe.

(3) Summary As shown in Table 1, comparing samples 1-6 molded from the same type of resin 1 with samples 7-10, samples 1-6 are excellent in light resistance and have a light-resistant stabilizer layer on the surface. It can be seen that it is useful for suppressing light resistance deterioration. Further, when the samples 11 to 14 molded from the resin 2 different in kind from the resin 1 were compared with the sample 15, the same result as above was 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 37a Front surface 37b Back surface 38 Sensor lens group 39 Sensor 40 Two-dimensional actuator 50 Molding part 52 Concave part 55 Light-resistant stabilizer layer 60 Reflection Prevention film 61 1st layer 62 2nd layer D Optical disk D ₁ Protective substrate D ₂ Information recording surface

Claims

An optical element used in an optical pickup device using a light source that emits laser light having a wavelength of 380 nm to 420 nm,
A molded part composed of an alicyclic olefin resin;
A light-resistant stabilizer layer formed on the surface of the molded part;
An optical element comprising:
The optical element according to claim 1,
A concave portion having a depth of 1 μm or less is formed on the surface of the molded portion, and the light-resistant stabilizer layer is formed in the concave portion.
The optical element according to claim 1,
An optical element, wherein an antireflection film is formed on the light-resistant stabilizer layer.
The optical element according to any one of claims 1 to 3,
The optical element, wherein the light-resistant stabilizer contained in the light-resistant stabilizer layer is a hindered amine light-resistant stabilizer.
The optical element according to any one of claims 1 to 3,
The optical element, wherein the light-resistant stabilizer contained in the light-resistant stabilizer layer is a water-soluble hindered amine light-resistant stabilizer.
The optical element according to any one of claims 1 to 5,
An optical element, wherein a light resistance stabilizer of 1% by mass or less is added to the molded part.
The optical element according to claim 6,
The optical element, wherein the light-resistant stabilizer added to the molded part is a hindered amine light-resistant stabilizer.
An optical pickup device using the optical element according to any one of claims 1 to 7 as an objective lens,
A light source that emits laser light having a wavelength of 380 nm to 420 nm;
The objective lens receiving the laser beam;
An optical pickup device comprising:
A method of manufacturing an optical element used in an optical pickup device having a light source that emits laser light having a wavelength of 380 nm to 420 nm,
Forming a molded part by molding an alicyclic olefin resin;
Forming a light-resistant stabilizer layer on the surface of the molded part;
An optical element manufacturing method comprising:
In the manufacturing method of the optical element according to claim 9,
In the step of forming the light-resistant stabilizer layer, the molded part is dipped in a solution in which the light-resistant stabilizer is dissolved.
In the manufacturing method of the optical element according to claim 9,
In the step of forming the light-resistant stabilizer layer, a solution in which the light-resistant stabilizer is dissolved is applied to the molded part and dried, and this is repeated a plurality of times.