JP2505893B2 - Optical element molding method and optical element molding die manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing an optical element made of glass such as a lens and a prism by press molding of a glass material, and a mold used for the press molding. Is.

[Prior Art] The technology of manufacturing a lens by press molding of a glass material without requiring a polishing step eliminates the complicated steps required in the conventional manufacturing of a lens, and can simply and inexpensively manufacture a lens. In recent years, it has come to be used for manufacturing not only lenses but also optical elements made of glass such as prisms.

The properties required for the mold material used for press molding of such glass optical elements include excellent hardness, heat resistance, releasability, and mirror surface workability. Heretofore, as this type of mold material, many proposals have been made on metals, ceramics and materials coated with them. If some examples, 13Cr martensitic steels in JP 49-51112 is, the SiC and Si ₃ N ₄ in JP 52-45613, the JP 60-246230 cemented carbide No. 6-183134 proposes a material coated with a noble metal, and JP-A-61-183134 proposes a material coated with a diamond thin film or a diamond-like carbon film.

[Problems to be Solved by the Invention] However, 13Cr martensitic steel has a drawback that it is easily oxidized, and further, Fe diffuses into the glass at a high temperature and the glass is colored. It is generally said that SiC and Si ₃ N ₄ are difficult to oxidize, but at high temperature, oxidation also occurs and a SiO ₂ film is formed on the surface, causing fusion with glass and further increasing hardness. It has the drawback that its processability is extremely poor. A material coated with a noble metal is unlikely to cause fusion, but since it is extremely soft, it has the drawback of being easily scratched and easily deformed.
Further, the material coated with the diamond thin film lacks the smoothness of the surface, so that the specularity of the obtained optical element is insufficient.

Further, Japanese Patent Application Laid-Open No. 61-183134 discloses a mold material coated with a diamond-like carbon film, and the film structure of the diamond-like carbon film has a hydrogen content, a mixed state of a crystalline phase and an amorphous phase, or sp of carbon atoms. It is diverse and complicated due to the mixed state of ² , sp ³ hybrid orbitals. That is, since the film structure strongly depends on the film forming method and film forming conditions, even if it is generally referred to as a diamond-like carbon film, lead in the glass component is precipitated in glass forming or the film peels when the number of forming times increases. And the like, resulting in insufficient moldability and durability.

In addition, if molding is performed using a mold coated with the above-mentioned diamond-like carbon film, problems such as glass fusion, lead deposition, and scratches occur, so these molds should be used continuously. In order to do so, it is necessary to mechanically polish (clean) the mold surface with diamond powder or the like every suitable number of times of molding. However, the mold shape changes and deteriorates as the number of cleanings increases. Therefore, the mold is mechanically processed every suitable number of cleanings.
It is necessary to polish it back to its original shape. However, since the material of the die base material generally has high hardness, it is not always easy to regenerate it into a desired shape because mechanical processing and polishing are not a container, and this tendency is particularly remarkable in the case of an aspherical shape. . Therefore, the reproduction of the mold by such a method causes a large cost increase in the process of manufacturing the optical element by press molding.

Therefore, an object of the present invention is to provide a molding method for an optical element, in which precipitated lead, fused glass and the like on the mold surface are removed and molding is performed while a clean molding surface is always exposed. An object of the present invention is to provide a method for molding an optical element that does not require finish polishing of molded glass. It is an object of the present invention to provide a method for producing a mold for molding an optical element, which does not deform or deteriorate the mold by removing the damaged film of the mold without using mechanical processing or polishing.

[Means for Solving the Problems] The present invention provides a method for molding an optical element by performing cleaning, which is a problem in the conventional optical element molding mold, and further, regenerating the mold by a dry process as a part of the molding process. It is a method of molding an optical element and a method of manufacturing a mold for molding an optical element, which realizes mold durability, moldability, and cost reduction.

That is, the present invention is a method for molding an optical element in which a film containing carbon as a main constituent element is formed using an optical element molding die in which a molding surface is formed, molding is performed, and then the surface of the film is etched. In the method for molding an optical element, which is characterized in that molding is performed after the removal by the method, and in the method for producing an optical element molding die in which a film containing carbon as a main constituent element is formed on the molding surface, the film is etched. The method for producing an optical element molding die is characterized in that the film is newly formed after being removed by.

First, the method for molding an optical element of the present invention will be described in detail.

In the method of molding an optical element of the present invention, press molding of glass is performed using a mold in which a film having carbon as a main constituent element (hereinafter referred to as a carbon-based film) is formed on a mold base material, and then the film surface is formed. The film surface is cleaned by etching, and then molding is performed again.

As the die base material, a material that can be precision processed and has heat resistance and impact resistance, for example, tungsten carbide, cermet, zirconia, SiC, Si ₃ N ₄ is used.

As the carbon-based film, for example, a diamond thin film, a diamond-like carbon film, a hydrogenated amorphous carbon film (hereinafter,
a-C: H film).

As the carbon-based film, for example, a diamond thin film, a diamond-like carbon film, a hydrogenated amorphous carbon film (hereinafter,
a-C: H film).

Among the carbon-based films, the diamond thin film is formed by the microwave plasma CVD method, the hot filament CVD method, the plasma jet method, the ECR-PURAZUMACVD method, etc., and the diamond-like carbon film and the aC: H film are formed by the plasma CVD method, the ion beam method. -It is formed by a sputtering method, an ion beam vapor deposition method, a plasma sputtering method, or the like. The thickness of these films is usually several thousand Å
〜Several μm is suitable. The gas used for formation is a carbon-containing gas such as methane, ethane, propane, ethylene, benzene, acetylene, and other hydrocarbons; methylene chloride, carbon tetrachloride, chloroform, trichloroethane, and other halogenated hydrocarbons; methyl alcohol, ethyl alcohol, etc. Alcohols; (CH ₃ ) ₂ CO, (C ₆ H ₅ ) ₂ CO, etc. ketones; CO, CO _2, etc. gases, and N ₂ , H ₂ , O ₂ , H ₂ O, It is a mixture of gases such as Ar.

An optical element made of glass is press-molded using this mold. After that, the mold surface is dry-etched to clean the surface.

A plasma etching method, a sputter etching method, an ion beam etching method, a reactive ion etching method, or the like is used for the doti etching. The etching amount may be several Å to several tens of Å. As the etching gas, O ₂ , H ₂ , N ₂ , air, a rare gas typified by Ar, CF _4, etc., and a mixed gas thereof are used. In particular, the method of oxidizing a carbon-based film with oxygen plasma is
Complete cleaning is possible because the film can be gasified and removed by a chemical reaction. The etching amount at this time may be about several tens of liters at the maximum.

In addition, it is preferable to select etching conditions that do not deteriorate the surface shape of the mold, especially the surface roughness, by etching. That is, when oxygen is used to etch (ash) a carbon-based film, carbon is oxidized and removed.
At this time, it is difficult to etch (ash) only the carbon-based film, and usually the surface of the die base material is also etched (ashed) and the surface of the die base material is also oxidized. As a result, when the carbon-based film is formed again, the adhesion between the mold base material and the film is reduced and the surface roughness of the mold base material is increased, so that the performance of the molded product is deteriorated. Further, when the die base material made of a cemented carbide containing Co is etched by Ar ion beam, only Co is selectively etched, so that the surface roughness of the die base material is increased. Therefore, when etching a carbon-based film for the purpose of cleaning, it is preferable to use a method and conditions that minimize the etching rate.

For example, in the case of etching of several tens of liters, the etching amount is controlled in a time period longer than the experimentally obtained etching rate.

Further, without using the method of etching, it is also effective to clean the film surface by thermally oxidizing the mold base material at 750 ° C. or higher in an oxygen atmosphere.

By using an in-line configuration that performs etching for cleaning in the molding chamber, frequent etching
Further, it can be performed for each molding.

Next, the method for manufacturing the optical element molding die of the present invention will be described in detail.

In the production method of the present invention, first, the carbon-based film on the die base material is etched to completely remove the film without impairing the surface shape of the die base material, and then the carbon-based film is formed on the die base material. Form anew.

The etching for completely removing the film can be performed in the same manner as the etching for cleaning.
At this time, it is preferable to select etching conditions so that the shape of the surface of the mold base material, particularly the surface roughness, is not deteriorated, and when the etching gas contains oxygen, the surface of the mold base material is not oxidized. . That is, when a carbon-based film is etched (ashed) by using oxygen, carbon is oxidized and removed. At this time, however, it is difficult to etch (ash) only the carbon-based film, and the surface of the normal base material is also etched (ashed). The surface of the die base material is also oxidized. As a result, when the carbon-based film is formed again, the adhesion between the mold base material and the film is reduced and the surface roughness of the mold base material is increased, so that the performance of the molded product is deteriorated. Further, when the die base material made of a cemented carbide containing Co is etched by Ar ion beam, only Co is selectively etched, so that the surface roughness of the die base material is increased.

Further, when completely removing the carbon-based film, the carbon-based film is etched (ashing) by oxygen plasma or the like.
And before the die base material is etched (ashed)
Etching (ashing) is performed without damaging the surface of the die base material by switching to a method or condition with a low etching rate such as Ar plasma. Here, the etching method and conditions are switched when etching is performed while monitoring the emission intensity of the etching substance by plasma emission analysis, and when the emission intensity falls below a certain intensity.

The time when the mold used in the molding method of the present invention is regenerated by this manufacturing method can be determined as follows.
In molding having an etching step for cleaning, the carbon-based film on the die base material gradually becomes thinner as the number of moldings increases, and the film eventually disappears.
Therefore, the reflectance of the mold (mold base material + carbon-based film) is monitored by utilizing the fact that the light reflectance is different between the case where the carbon film is present on the die base material and the case where it is not present. The time when the reproduction becomes very thin and the reflectance approaches the reflectance of the mold base material itself is the reproduction time.

By adopting an in-line configuration in which the etching is performed in the molding chamber, the molding process and the process of completely removing the film to regenerate the mold can be performed consistently. Particularly, according to the microwave plasma CVD method, the ECR-plasma CVD method, the ion beam sputtering method, the ion beam vapor deposition method, etc., etching and film formation can be continuously performed in the same apparatus in the molding chamber. However, it may be removed from the molding process and removed from the molding apparatus for etching.

EXAMPLES Example 1 Hereinafter, specific examples of the present invention will be described with reference to the drawings.

1 and 2 show an example of an optical element molding die used and manufactured in the present invention.

FIG. 1 shows a state before press molding of an optical element.
The figure shows the state after molding of the optical element. In FIG. 1, 1 and 2 are mold base materials, 1-a and 2-a are diamond-like carbon films formed on the molding surface of the mold base material in contact with the glass material, 3 is the glass material, and 2 In the figure, 4 is an optical element.

By pressing the glass material 3 placed between the molds as shown in FIG. 1, an optical element 4 such as a lens is formed as shown in FIG.

WC (95%) + Co (5
%) To form a diamond-like carbon film on the die base material. FIG. 5 shows a film forming apparatus used in this embodiment.

In FIG. 3, 11 is a vacuum container, 12 is an ion beam device, and 13
Is an ionization chamber, 14 is a gas inlet, 15 is an ion beam extraction grid, 16 is an ion beam, 17 is a mold base material, 18 is a substrate holder and heater, and 19 is an exhaust hole. When forming the diamond-like carbon film, the mold base material 17 whose surface has been cleaned with an organic solvent is placed on the holder 18, and the inside of the container 11 is set to 1 × 10 ⁻⁶ Torr by exhausting it through the exhaust hole 19. To do.

Next, the source gas CH ₄ + Ar mixed gas was introduced from the gas inlet 14 at a mixing ratio CH ₄ / Ar = 1/1, and the inside of the container 11 was 1 × 10 ⁻⁴ T.
orr. The raw material gas was ionized in the ionization chamber 13 of the ion beam device 12, an ion beam was extracted by applying −500 V to the ion beam extraction grid 15, and the base material 17 was irradiated to form a film having a thickness of 1.5 μm. At this time, the current value of the ion beam was 0.6 mA / cm ² , and the substrate was not particularly heated. The film formation time is 45 minutes. The surface roughness of the film thus obtained is Rmax × 0.01 to 0.02 μm, and the hardness is 1400 to 1600.
It is kg / mm ² .

Next, the oxygen partial pressure of impurities was set to 5 in 1.2 atom of N ₂ gas.
After annealing at 570 ° C. for 2 hours in an atmosphere of × 10 ^-3 Torr or less, a lens is molded by using the annealing treatment using the molding apparatus shown in FIG.

In FIG. 4, reference numeral 51 denotes a vacuum chamber main body, 52 denotes a lid thereof, 53 denotes an upper die for molding an optical element, 54 denotes a lower die thereof, 55 denotes an upper die holder for holding down an upper die, and 56 denotes a trunk die. , 57 is a mold holder,
Reference numeral 58 is a heater, 59 is a lifting rod for lifting the lower die, 60 is an air cylinder for operating the lifting rod, 61 is an oil rotary pump, 62, 63 and 64 are valves, 65 is an inert gas inflow pipe, 66
Is a valve, 67 is a leak pipe, 68 is a valve, 69 is a temperature sensor, 70 is a water cooling pipe, and 71 is a stand for supporting a vacuum chamber.

 The process of manufacturing the lens will be described below.

A flint type optical glass (SF14) is adjusted to a predetermined amount, a spherical glass material is placed in the mold cavity, and this is placed in the apparatus.

After placing the mold filled with glass material in the equipment, close the lid 52 of the vacuum chamber 51, let water flow through the water cooling pipe 70, and heat the heater.
Apply current to 58. At this time, the nitrogen gas valves 66 and 68 are closed, and the exhaust system valves 62, 63 and 64 are also closed. The oil rotary pump 61 is always rotating.

Open the valve 62 and start evacuation. When it becomes 10 ^-2 Torr or less, close the valve 62 and open the valve 66 to introduce nitrogen gas into the vacuum chamber from the cylinder. When the temperature reaches a predetermined temperature, the air cylinder 60 is activated to apply a pressure of 10 kg / cm ² for 5 minutes. After removing the pressure, the cooling rate is −5 ° C./min until the temperature reaches the dislocation point or lower. After that, cooling is performed at a rate of −20 ° C./min or higher. When the temperature drops to 200 ° C. or lower, the valve 66 is closed. The leak valve 63 is opened to introduce air into the vacuum chamber 51. Then, the lid 52 is opened, the upper mold retainer is removed, and the molded product is taken out.

As described above, the flint optical glass SF14 (softening point
Sp = 586 ° C., transition point Tg = 485 ° C.) was used to mold the lens 4 shown in FIG. FIG. 5 shows a molding condition, that is, a time-temperature relationship diagram at this time.

Table 1 shows the results of measuring the surface roughness of the molded lens and the surface roughness of the mold before and after molding.

When this mold was further molded 500 times, a minute peeling occurred on the mold due to foreign matter that was considered to have been introduced when the glass material was installed.

In order to regenerate this mold, the diamond-like carbon film is etched by being installed in the ion beam deposition apparatus shown in FIG.

First, the inside of the container 11 is exhausted from the exhaust hole 19 to 1 × 10 ^−6.
Torr. Next, the etching gas O ₂ is supplied through the gas inlet 14.
A + Ar mixed gas is introduced at a mixing ratio of O ₂ / Ar = 1/1, and the inside of the container 11 is adjusted to 1 × 10 ⁻⁴ Torr. The raw material gas is ionized in the ionization chamber 13 of the ion beam device 12, and the ion beam is extracted at an acceleration voltage of 200 V to perform etching. At this time, the substrate is not particularly heated. At this time, the emission spectrum monitor 20 monitors the temporal change in the intensity of the ultraviolet light with a wavelength of 297.7 nm, which is the emission from CO that is electronically excited,
Control etching. In particular, excessive etching causes radiation damage and surface oxidation of the mold base material,
When the emission intensity shown on the emission spectrum monitor falls below a certain level, supply of O ₂ gas is stopped, the accelerating voltage is reduced to 50 V, the Ar ion beam is changed, and the remaining diamond-like carbon film is removed by etching. To do.

The mold after the completion of etching was taken out from the vacuum container 11 and its surface roughness was measured. As a result, Rmax was 0.03 μm and no deterioration due to etching was observed. Moreover, when the surface oxide layer was analyzed by ESCA, only an oxide layer of the order of a natural oxide layer, which was considered to be generated at the time of taking out after completion of etching, was observed. Usually, since the diamond-like carbon film is continuously formed under the above conditions after the etching is completed, there is no fear of oxidation. In this way, the surface roughness of the mold on which the diamond-like carbon film was formed again was Rmax 0.03 μm and the Vickers hardness was 1400 to 1600 kg / mm ² , and the same performance as the film initially formed was obtained.

Example 2 Electron cyclotron resonance plasma CVD method (ECR-PCVD
Method) is used to form an aC: H film on the mold base material made of WC (90%) + Co (10%).

The ECR plasma device is a cavity resonator type shown in FIG. 6 and applies a magnetic field to the cavity resonator 81 with the electromagnet 82, introduces microwaves from the microwave introduction window 83 through the waveguide 84, and from the gas introduction port 85. The gas is introduced into the cavity resonator to excite the gas. The magnitude of the magnetic field was set so that it was 500 Gauss on the 2000 Gauss type surface at the microwave inlet. The mold 87 supported by the mold holder 86 was placed outside the cavity resonator as shown in FIG.

Next, from the gas inlet 85 CO (10SCCM), H ₂ (20SCCM)
Was introduced into the cavity resonator, the pressure was 5 × 10 ^-2 Torr, the microwave power was 600 W, and the substrate temperature was 300 ° C.

After that, glass molding was performed using this mold in the same manner as in Example 1, and the mold used for molding was installed again in this apparatus to etch the film.

O ₂ was used as the etching gas, which was introduced through the gas inlet 85.
Introduce 100 SCCM and turn into plasma in the cavity resonator. At this time, the pressure is 5 × 10 ⁻³ Torr and the substrate is not heated. The size of the magnetic field was 2500 Gauss at the microwave inlet and 875 Gauss at the cavity resonator outlet, and the mold was set at this point, and etching (ashing) was performed with microwave power 900W. As in Example 1, the end point of etching was monitored by plasma emission, and when the emission intensity fell below a certain value, O ₂ was switched to Ar and the remaining film was etched. At this time, the conditions of pressure, microwave power, and magnetic field were the same as in the case of O ₂ gas. However, the position of the substrate was 130 mm from the cavity resonator outlet. Then, an aC: H film was formed under the above-mentioned film forming conditions, and the surface roughness and hardness of the obtained mold were measured. As a result, a mold having the same performance as that of the first embodiment was regenerated. I was able to.

Example 3 Using the mold prepared under the same method and conditions as in Example 1, glass molding was carried out by the molding apparatus shown in FIG.

Next, an example in which a glass lens is press-molded by the above mold will be described in detail.

In FIG. 7, 104 is a substitution chamber for intake, 106 is a forming chamber / etching chamber, 108 is a vapor deposition chamber, and 110 is a vapor deposition chamber.
Is a replacement chamber for extraction. Reference numerals 112, 114, 116, 151, 152 are gate valves, 118 is a rail, and 120 is a pallet that can be conveyed on the rail in the direction of arrow A. 124,
138, 140 and 149 are cylinders, and 126 and 150 are valves. A heater 128 is arranged along the rail 118 in the molding chamber 106.

In the molding chamber 106, a heating zone 106-1, a press zone 106-2, and a slow cooling zone 106
-3. In the press zone 106-2, the lower end of the rod 134 of the cylinder 138 is attached to the upper mold member 13 for molding.
The fixed lower mold member 132 is fixed to the upper end of the rod 136 of the cylinder 140. The upper mold member 130 and the lower mold member 132 are the mold members manufactured and used in the present invention shown in FIG.

13.56MHz RF power supply 155,156 for mold and cylinder
, The mold member portion functions as an electrode, and is insulated from the molding chamber by insulators 158 and 159.
Here, 153 and 154 are shields.

In the vapor deposition chamber 108, a container containing the vapor deposition material 146.
142 and a heater 144 for heating the container are arranged.

Flint optical glass (SF14, softening point Sp = 586 ° C., glass transition point Tg = 485 ° C.) was roughly processed into a predetermined shape and size to obtain a blank for molding.

The glass blank is placed on the pallet 120 and placed at the position 120-1 in the intake / replacement chamber 104, and the pallet at that position is pushed in the direction A by the rod 122 of the cylinder 124 to pass through the gate valve 112 and 120 in the forming chamber 106. -2 position, and thereafter, a pallet is newly placed in the replacement chamber 104 at a predetermined timing in the same manner, and the pallet is moved in the molding chamber 106 at a position of 120-2 → ... → 120-8. It was sequentially transported to. In the meantime, in the heating zone 106-1, the glass blank is gradually heated by the heater 128 to reach the softening point or higher at the position 120-4, and then conveyed to the press zone 106-2 via the gate valve 151, where The cylinders 138 and 149 are operated and pressed by the upper mold member 130 and the lower mold member 132 at a pressure of 10 kg / cm ² for 5 minutes, then the applied pressure is released and the glass is cooled to a temperature below the glass transition point, and then the cylinders 138 and 140 are operated to operate the upper cylinder. The mold member 130 and the lower mold member 132 were released from the glass molding. At the time of the pressing, the pallet was used as a body member for molding.

The glass molding passes through the gate valve 152 and the slow cooling zone 106
It moves to -3 and is gradually cooled. The inside of the molding chamber 106 was filled with an inert gas.

After the glass molded product is conveyed to the slow cooling zone, the press zone 106-2 is closed to the gate valves 151 and 152 and exhausted to 1 × 10 ⁻⁶ Torr by an exhaust system (not shown). Next, 200 SCCM of O ₂ gas was introduced from the etching gas introduction line 157, the pressure inside the press zone (molding chamber) was set to 1 Torr, and the RF power supply of 13.56 MHz was used.
RF power of 100 W is input by 5,156 to generate RF oxygen plasma. This plasma is generated for 30 seconds, and the mold member 13
Etch the diamond-like carbon film on 0,132 by 20Å. After that, an inert gas was introduced into the press zone (molding chamber) 106-2, and when the force became equal to that of 106-1 and 106-3, the gate valves 151 and 152 were opened, and the pallet on which a blank for molding was newly mounted was opened. It is conveyed to the molding chamber 106-2 and molding is performed.

The pallet that has reached the position 120-8 in the molding chamber 106 is moved over the gate valve 114 in the next transfer, and is then moved to the vapor deposition chamber 108.
Was transported to the position 120-9. Usually, vacuum deposition is performed here, but in this example, the deposition was not performed. Then, in the next transportation, the material was transported over the gate valve 116 to the position 120-10 in the take-out replacement chamber 110. Then, at the time of the next conveyance, the cylinder 149 is operated to operate the rod 1
The glass molded article was taken out of the molding apparatus 102 by 48.

Etching of the mold member may be performed after every molding, or after molding a few shots. In this case, it is necessary to adjust the etching time.

The surface roughness of the molding surface of the mold member and the surface roughness of the molded optical element after molding 3000 times by the pressing process and the conventional process as described above, and the mold release between the molded optical element and the mold member. The sex is shown in Table 2.

As described above, according to the present embodiment, since the clean surface is always exposed during molding, the performance of the molding surface of the mold member and the optical surface of the molded optical element is constant without changing from the initial stage. It was

Example 4 Using a mold prepared under the same method and conditions as in Example 1, glass was formed by the apparatus shown in the schematic view of FIG.

In FIG. 8, 161 is a loading / unloading chamber for loading a glass blank and unloading the molded and coated optical element, 162 is a mold and blank preheating chamber, 163 is a molding chamber, 164 is a cooling chamber, and 165 is 165. Mold cleaning room, 166
Is a coating room, and the gate valve 171 is between each room.
Partitioned by ~ 176.

A blank obtained by roughly processing a flint type optical glass (SF14, softening point Sp = 586 ° C., glass transition point Tg = 485 ° C.) into a predetermined shape and size is placed in a die in a loading / unloading chamber 161. The mold is moved to the preheating chamber 162 through the gate valve 171, the mold and the blank are gradually heated to a softening point or higher, and then moved to the molding chamber 163. Then, at this position, after pressing with a cylinder unit (not shown) at a pressure of 10 kg / cm ² for 5 minutes, it is moved to the cooling chamber 164. Then, the pressure is released, the temperature is cooled to a temperature below the glass transition point, and the mold is released from the glass molded product. Then, the glass molded product is moved to the coating chamber 166, where predetermined coating is performed, and then moved to the loading / unloading chamber 161 to be taken out. On the other hand, the molded mold was subjected to the same method and conditions as in Example 3 in the cleaning chamber 165 to remove the film on the mold at 4Å / s.
Etch 40Å at ec etching rate.

After that, the mold is moved to the loading / unloading chamber 161 through the coating chamber 166, and a new blank is loaded. In addition,
The coating chamber 166 has a structure capable of coating not only glass but also mold surface.

In this example as well, as in Example 3, since a clean surface was always exposed during molding, the performance of the molding surface of the mold member and the optical surface of the molded optical element remained constant from the beginning. there were.

[Effects of the Invention] As described above, in a step of press-molding an optical element using an optical element molding die in which a film having carbon as a main constituent element is formed, the die is etched after molding, By performing the subsequent molding thereafter, there is an effect that good molding is performed every time. Furthermore, by removing the film by etching or ashing at the time of regenerating the mold, it becomes possible to remanufacture without mechanical processing or polishing of the mold, resulting in cost reduction in the molding process of the optical element. effective.

[Brief description of drawings]

1 and 2 are cross-sectional views showing an example of an optical element molding die manufactured and used in the present invention. FIG. 1 shows a state before press molding, and FIG. 2 shows a state after press molding. Show. 3 and 6 are schematic views showing a film forming apparatus used in the present invention, FIG. 3 is an ion beam vapor deposition apparatus, and FIG. 6 is an ECR plasma apparatus. FIGS. 4, 7 and 8 are sectional views showing a lens molding apparatus used in the method of molding an optical element according to the present invention. FIG. 4 is a discontinuous molding type, FIGS. Is a continuous molding type. FIG. 5 is a time-temperature relationship diagram during lens molding. 1,2 ... Mold base material, 1-a, 2-a ... Diamond-like carbon film, 3
… Glass material, 4… Molded lens, 11… Vacuum container,
12 ... Ion beam device, 13 ... Ionization chamber, 14 ... Gas inlet port, 15 ... Ion beam extraction grid, 16 ... Ion beam, 17 ... Mold base material, 18 ... Substrate holder and heater, 19 ...
Exhaust system, 20 ... Plasma generation monitor. 51 ... vacuum tank, 52 ...
Vacuum tank lid, 53 ... Upper mold, 54 ... Lower mold, 55 ... Upper mold hold,
56 ... Body type, 57 ... Mold holder, 58 ... Heater, 59 ... Lifting rod that raises the lower mold, 60 ... Air cylinder, 61 ... Oil rotary pump, 62, 63, 64 ... Valve, 65 ... Inert gas introduction pipe,
66 ... Valve, 67 ... Leak pipe, 68 ... Valve, 69 ... Temperature sensor, 70 ... Water cooling pipe, 71 ... Vacuum tank supporting base, 81
… Cavity resonator, 82… Electromagnet, 83… Microwave introduction window, 84
... microwave waveguide, 85 ... gas inlet, 86 ... mold holder, 87 ... mold base material, 88 ... exhaust port, 102 ... molding device, 104 ... substitution chamber for intake, 106 ... molding chamber, 108 ... deposition chamber, 110 ... Replacement chamber for taking out, 112 ... Gate valve, 114 ... Gate valve,
126 ... Gate valve, 118 ... Rail, 120 ... Pallet, 122
... rod, 124 ... cylinder, 126 ... valve, 128 ... heater, 130 ... upper mold, 132 ... lower mold, 134 ... rod, 136 ... rod, 138 ... cylinder, 140 ... cylinder, 142 ... container, 144 ...
Heater, 146 ... Vapor deposition material, 148 ... Rod, 149 ... Schilling, 150 ... Valve, 151 ... Gate valve, 152 ... Gate valve, 153 ... Shield, 154 ... Shield, 155 ... RF power supply, 1
56 ... RF power supply, 157 ... Gas inlet, 158 ... Insulator, 159 ... Insulator, 161 ... Loading / unloading chamber, 162 ... Preheating chamber, 163
… Molding room, 164… Cooling room, 165… Cleaning room, 166…
Coating chamber, 171 ... Gate valve, 172 ... Gate valve, 173 ... Gate valve, 174 ... Gate valve, 175 ... Gate valve, 176 ... Gate valve.

Claims (2)

(57) [Claims] 1. A method of molding an optical element, which comprises molding using a mold for molding an optical element having a film whose main constituent element is carbon formed on a molding surface, wherein molding is performed, and then the surface of the film is etched. A method for molding an optical element, which comprises molding after removing. 2. A method of manufacturing an optical element molding die in which a film containing carbon as a main constituent element is formed on a molding surface, wherein the film is newly formed after the film is removed by etching. A method for manufacturing an optical element molding die.