JPH08259241A - Optical element molding method - Google Patents

Abstract

PURPOSE: To improve productivity of the optical devices by improving releasability of the glass from the forming mold at and after the time of performing the initial shots in the forming operation by treating the surface of each of glass blanks and the forming surface of a forming mold so as to have specified surface conditions respectively at the time of press-forming optical devices consisting of glass. CONSTITUTION: In this method, the surface of each of glass blanks is coated with a carbon film that is preferably a hydrocarbon film and the forming surface of an optical device forming mold consists of a hard carbon film. The hydrocarbon film used for coating the surface of each of the glass blanks is preferably formed by a plasma CVD method, an ion beam film forming method or carbon ion implantation. The hard carbon film used as the forming surface of the forming mold is preferably a film selected from diamond films, diamond- like thin films and hydrogenatcd amorphous carbon films.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for press molding a glass material into an optical element made of glass such as a lens and a prism.

[0002]

2. Description of the Related Art A technique for manufacturing a lens by press molding a glass material without the need for a polishing step eliminates the complicated process required in the conventional lens manufacturing,
It has become possible to manufacture lenses easily and inexpensively, and it has come to be used for manufacturing not only lenses but also prisms and other optical elements made of glass.

Properties required for the mold material used for press molding of such glass optical elements include excellent hardness, heat resistance, mold release property, mirror surface workability and the like. Heretofore, as this type of mold material, many proposals have been made such as metals, ceramics and materials coated with them. To give some examples, JP-A-49-
51112 discloses 13Cr martensitic steel, and JP-A-52-45613 discloses SiC and Si ₃ N _4.
However, in JP-A-60-246230, a material obtained by coating a cemented carbide with a noble metal is disclosed in JP-A-61-18.
Nos. 3134, 61-281030 and 1-301864 disclose materials coated with a diamond thin film or a diamond-like carbon film, and JP-A 64-83529 discloses coating with a hard carbon film. The proposed material is proposed.

Further, Japanese Unexamined Patent Publication No. 4-321525 proposes coating a glass blank surface with carbon, and Japanese Unexamined Patent Publication No. 6-32623 proposes ion-implanting carbon into the blank surface. Proposals that improve the quality are also made.

[0005]

However, 13Cr martensitic steel is apt to oxidize, and further, Fe diffuses into the glass at a high temperature and the glass is colored. Although SiC and Si ₃ N ₄ are generally considered to be difficult to oxidize, they also oxidize at high temperatures, resulting in SiO 2 on the surface.
_Since the film of ₂ is formed, it fuses with the glass. on the other hand,
A material coated with a noble metal is difficult to cause fusion, but it is extremely soft and therefore easily scratched and deformed. Also, when a die in which a hydrocarbon film containing CH ₃ or CH ₂ or a carbon film on which graphite is vapor-deposited is formed on a die base material made of cemented carbide or ceramics is used for molding, the film is consumed in about several shots. Resulting in. In addition, when a glass blank coated with a hydrocarbon film is used for molding, the mold release of the molded product from the mold is good, but when the mold material has a large adhesive force with the carbon film (for example, when the mold surface is oxide or In the case of nitrides, etc.), carbon accumulates on the surface of the mold every time molding is performed. When carbon is deposited, the surface roughness of the mold is deteriorated, the shape is transferred to the lens and the lens becomes cloudy, and a good lens cannot be obtained.

On the other hand, the hard carbon film has good releasability, does not cause fusion with glass, has high hardness, and has wear resistance,
It is one of the good mold materials. However, even a hard carbon film may be difficult to release. As a first example, the hard carbon film maintains a strong bonded state from the start of press molding to about 20 shots, and there is almost no graphite-like portion, so there is a problem that the mold release is difficult.

As a second example, in the case of a convex lens shape, even if the temperature is such that a mold is easily released, a meniscus lens having a certain shape does not release it. Such a phenomenon is considered to occur for the following reasons. The mold release phenomenon between the mold and the lens is considered to be caused by the difference in the coefficient of thermal expansion between the mold and the glass. That is, it is considered that when the glass lens is gradually cooled according to the process conditions after press molding, the amount of shrinkage varies depending on the coefficient of thermal expansion of each mold glass, so that a large shear stress acts on the mold-glass interface to cause mold release. However, when the lens shape is different, the shear stress acting on the mold-glass interface varies greatly depending on the temperature.
Mold release may not occur unless the temperature is lower than ℃. As described above, the mold release property is poor, that is, the lower the mold release temperature, the longer one molding cycle takes, and the number of lenses that can be manufactured in a unit time is limited, which leads to an increase in cost.

On the other hand, in order to give various optical performances to the optical element, press molding with various glass materials is performed, but depending on the glass material, the carbon film as the release film may be rapidly consumed. However, such a glass material significantly deteriorates the durability of the mold.

[0009]

In order to achieve the above object, the present invention uses a mold having a hard carbon film, which is one of conventional mold releasing films, and further uses a carbon-based film having good mold releasing property. The above problem is solved by performing press molding using a glass blank coated with.

That is, the present invention is characterized in that, in the method of press-molding an optical element made of glass, the glass blank surface is covered with a carbon film, and the molding surface of the optical element molding die is made of a hard carbon film. Is a method of molding an optical element.

The operation will be described below. As one method for solving the above problems, it is possible to reduce the adhesion between the mold and the glass during molding. A hard carbon film, which is one of the conventional release films, has a high bondability, but when the temperature is maintained for a long time, the structure tends to change gradually (graphitization) and the release property tends to be improved. However, it is difficult to improve the state of poor mold release that occurs in the initial stage of molding and the difficult state of mold release in the shape like a meniscus lens, only with the hard carbon film formed on the mold surface. Therefore, in order to give mold release properties to the glass blank as well, the surface of the glass blank is coated with a carbon film, and a carbon film-to-carbon film state is realized at the interface between the mold and the glass during molding. The problem is solved by lowering the adhesiveness. This allows
Even with a mold in which carbonization of the hard carbon film has not yet started at the start of molding, the effect of the carbon film on the surface of the glass blank enables mold release at high temperature from the first shot, and the molding cycle can be shortened. Further, by realizing a carbon film-to-carbon film state at the interface between the mold and the glass, it is possible to easily release the mold even in a shape such as the above meniscus lens that does not easily release.

In addition, the hard carbon film formed on the mold surface is extremely consumed, for example, in the case of a certain phosphoric acid type glass,
By coating the surface of the glass blank with carbon,
By exhausting the carbon coated on itself during press molding, the durability of the hard carbon film on the mold surface could be extended and the above-mentioned problems could be solved.

[0013]

【Example】

[Example 1] (CH blank (RF) vs i-C / TiN
/ Cemented Carbide Mold) FIGS. 1 and 2 show an embodiment of an optical element molding mold according to the present invention. In FIG. 1, 1 is a die base material made of cemented carbide, 2 is a hard intermediate layer made of TiN, 3 is a molding surface made of a hard carbon film for molding a glass material, and 4 is a glass material. The surface of this glass blank is covered with a hydrocarbon film 5. As shown in FIG. 2, an optical element 6 such as a lens is formed by press molding a glass material 4 placed between molds.

Next, the optical element molding die of the present invention will be described in detail. After processing a WC-Ti based cemented carbide as a mold base material into a predetermined shape, a TiN film was formed by ion plating, and then the molding surface was Rmax. = 0.02
What was mirror-polished to μm was used. After thoroughly cleaning this mold, the IBD (Ion Beam Dep) shown in FIG.
position) device. In FIG. 3, 7 is a vacuum chamber,
8 is an ion beam device, 9 is an ionization chamber, 10 is a gas introduction port, 11 is an ion beam extraction grit, 12 is an ion beam, 13 is a mold base material, 14 is a substrate holder and heater, and 15 is an exhaust port. First, 35 sccm of argon gas is introduced into the ionization chamber through the gas introduction port 10 for ionization, and then 500 V is applied to the ion beam extraction grit.
Voltage is applied to extract the ion beam, and
The molded surface was cleaned by irradiation for minutes. Then CH ₄ :
15 sccm, H ₂ : 30 sccm were introduced into the ionization chamber to make the gas pressure 3.5 × 10 ^-2 Pa, and the acceleration voltage was 10 kV.
Extraction of ion beam with 35nm
Was formed into a mixing layer. At this time, the ion beam current was 30 mA, the current density was 2 mA / cm ² , and the substrate temperature was 30
It was set to 0 ° C. The mixing layer of the analysis sample prepared under the same conditions was used for XPS (Xray Photoelectron).
The result of the depth direction analysis by the spectroscopy is shown in FIG. As is clear from FIG. 4, the thickness of the mixing layer is 35 nm, and the carbon C concentration decreases from the surface side toward the die base material side. On the other hand, the concentrations of Ti and N atoms increase from the surface side toward the die base material side.
A hard carbon film layer having a mixing layer was formed by the above method.

Next, a method for forming a hydrocarbon film on the surface of the glass blank will be described. FIG. 5 is a schematic diagram showing a schematic configuration of a thin film deposition apparatus for forming a hydrocarbon film. In FIG. 5, 16 is a vacuum chamber, 17 is an exhaust port, 18 is a heater, 1
9 is a heater power supply, 20 is a glass material support, 21 is a bias power supply, 22 is a glass material, 23 is a high frequency applying antenna, 24 is a matching circuit, 25 is a high frequency power supply, and 26 is a gas introduction pipe.

A glass material 22 that has been thoroughly washed is
Attached to the material support stand 20, heated to 300 ° C with the heater 18.
1x1 in the vacuum chamber 16 by heating and exhausting from the exhaust port 17
0^-3After reducing the pressure to Pa or less, the gas introduction port 26
Argon gas from 5 × 10 ^-2Introduce until Pa,
Apply a high frequency of 300 W to the high frequency applying antenna 23.
The high-frequency discharge, and plasma-cleans the glass material 22.
I went to training. After that, the introduction of argon gas was stopped
1 × 10^-3Return to a vacuum degree of Pa, and then from the gas inlet 26 to C
H_Four1 x 10 gas^-1It was introduced until it reached Pa. Soshi
The high frequency applying antenna 23 with a high frequency of 500 W.
High-frequency discharge is applied to form a coating film with a thickness of about 20 nm.
did. In addition, in order for the releasing effect according to the present invention to appear, the film thickness
Must be at least 5 nm, and at 50 nm and above,
The appearance of the child may be defective. This moth
The results of infrared spectroscopy (IR) of the film coated on the lath material
As shown in FIG. CH as shown in the IR profile of FIG.
₃, CH₂It was a film containing many groups.

Next, an example in which press molding is performed using the optical element molding die according to the present invention will be described. FIG. 7 shows a molding apparatus, in which 51 is a vacuum tank main body, 52 is a lid thereof, 53 is an upper mold for molding an optical element, 54 is a lower mold thereof, and 55 is an upper mold retainer for pressing the upper mold. Reference numeral 56 is a barrel type, 57 is a die holder, 58 is a heater, 59 is a push-up rod for pushing up the lower die, 60 is an air cylinder for operating the push-up rod,
61 is an oil rotary pump, 62, 63, 64 are valves, 65
Is an inert gas inflow pipe, 66 is a valve, 67 is a leak valve, 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 steps for manufacturing the lens will be described below. A gob in which a flint optical glass (Pb-free SF6: trade name S-NPH1: transition point Tg = 563 ° C.) manufactured by Ohara Co., Ltd. is adjusted to a predetermined amount is placed in a mold cavity, and the gob is placed in a molding device. Install.
Then, the mold into which the glass material is charged is installed in the apparatus, the lid 52 of the vacuum chamber 51 is closed, water is flown through the water cooling pipe 70, and an electric current is flown through the heater 58. At this time, the nitrogen gas valves 66 and 68 are closed, and the exhaust system valves 62 and 63,
64 is also closed. The oil rotary pump 61 is always rotating. 1 Pa after opening the valve 62 and starting exhaust
When the following occurs, the valve 62 is closed and the valve 66 is opened 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 pressure of 1.5 Pa for 1 minute. After releasing the pressure, cooling rate −
Cool at 5 ° C./min to below the transition point, then cool at a rate of −20 ° C./min or more, and when the temperature drops below 200 ° C., close valve 66, open leak valve 63, and place in vacuum chamber 51. Introduce air. Then the lid 52
Open and remove the upper mold clamp and take out the molded product. The lens shown in FIG. 4 was molded using the flint type optical glass as described above.

By using the optical element molding die according to the present invention, the mold release temperature of the first shot of press molding (the temperature at which the optical element peels off from the mold during gradual cooling after press molding) is a conventional hard carbon film. Is 50 ℃ compared to the mold whose molding surface is
Increased (mold release temperature of the mold according to the invention: 540 ° C.). Since the mold release temperature of the first shot of press molding can be increased by the present invention, the cycle time of molding can be shortened.

Further, the flint glass N used for the main molding
When PH1D was molded by the conventional hard carbon film mold, the hard carbon film was rapidly consumed and the mold durability was only 100 shots. However, as described above, the hydrocarbon film formed on the glass material not only has the effect of releasing the mold, but is also consumed during molding, so that the hard carbon film of the mold itself can be protected and the number of durable shots can be 1000 shots. And The molding surface of the mold member and the surface roughness of the molded optical element after molding 1000 times by the above pressing process, and the releasability between the mold member and the molded optical element were good. Especially for the molding surface of the mold member, an optical microscope, a scanning electron microscope (S
Even when observed by EM), defects such as scratches and cracks, reaction precipitates of glass components, and fusion of glass were not found.

Further, as a result of manufacturing the respective optical element molding dies whose optical element shapes are a biconcave lens, a convex meniscus lens and a concave meniscus lens by the same method as the above, the mold releasing property is better than the conventional hard carbon film. Was confirmed. In particular, FIG.
In the case of the convex meniscus lens as shown in Fig. 3, in the case of the conventional hard carbon film, the optical element may not be released from the mold up to 350 ° C, but when the optical element molding mold of the present invention is used, it is stable. Release at 530 ° C is possible. Similar to the biconvex lens described in the first half of Example 1, there was no problem in continuous molding of the above-mentioned various shapes even if molding was performed 1000 times.

The lanthanum-based glass (La
K12) and crown type glass (SK12) were molded, but the mold durability was dramatically better than that of the above flint type, and 300
Even if molding was performed 0 times, there was no problem at all, and a good mold release effect was confirmed.

Example 2 (CH blank (i-beam) v
In the present invention, since the mold base material, the intermediate layer of TiN, and the hard carbon film were manufactured by the same method as in Example 1, the hydrocarbon film formed on the glass blank was The manufacturing method will be described in detail. In Example 1, a high frequency was used to generate CH ₄ plasma to form a hydrocarbon film, but in the present invention, the hydrocarbon film is formed on the glass blank surface using an ion beam. FIG. 9 shows an IBD apparatus for forming a carbon film on a glass blank. In FIG. 9, 30 is a vacuum chamber, 31 is an ion beam device, 32 is an ionization chamber, 33 is a gas inlet, 34 is an ion beam extraction grit, 35 is an ion beam, 36 is an ion beam blocking wall, and 37 is a glass blank fixing jig. Tools 38 and 39 represent exhaust ports.

First, the same Pb-free SF6 (S-NPH1) glass material as in Example 1 was washed in advance to remove dirt and dust, and then the glass blank fixing jig 3 shown in FIG.
7, the inside of the vacuum chamber 30 was depressurized to 4 × 10 ⁻³ Pa.

Next, after introducing argon gas into the ionization chamber at 10 sccm from the gas introduction port 33 for ionization, a voltage of 500 V is applied to the ion beam extraction grit to extract the ion beam, and both surfaces of the glass material are irradiated for 5 minutes. Then, the surface of the glass blank was washed. Next, the pressure inside the vacuum chamber was reduced to 4 × 10 ⁻³ Pa again, and then methane gas was introduced into the ionization chamber at 10 sccm and hydrogen gas at 20 sccm. And the gas pressure is 3.5 × 10 ^-2 Pa
After being ionized at a vacuum degree of, an ion beam was extracted at an accelerating voltage of 200 V and irradiated on the molding surface to form a 30 nm hydrocarbon film.

Next, as in Example 1, press molding was performed using an optical element molding die coated with a hard carbon film. As a result, the same effects as in Example 1 were observed, the molding surface of the mold member after molding 1000 times and the surface roughness of the molded optical element, and the releasability between the mold member and the molded optical element. Was good. In particular, when the molding surface of the mold member was observed with an optical microscope or a scanning electron microscope (SEM), defects such as scratches and cracks, reaction deposits of glass components, and glass fusion did not occur. Further, as a result of producing the respective optical element molding molds whose optical element shapes are a biconcave lens, a convex meniscus lens, and a concave meniscus lens by the same method as the above, it is not possible to obtain with a conventional hard carbon film coating mold, it is better Releasability was confirmed. In particular, in the case of the convex meniscus lens as shown in FIG. 8, in the case of the conventional hard carbon film, the optical element may not be released from the mold up to 350 ° C. However, the optical element molding mold of the present invention was used. In this case, stable mold release at 530 ° C. was possible. Similar to the biconvex lens described in the first half of Example 1, there was no problem in continuous molding of the above-mentioned various shapes even if molding was performed 1000 times.

The lanthanum-based glass (La
K12) and crown type glass (SK12) were molded, but the mold durability was dramatically better than that of the above flint type, and 300
Even if molding was performed 0 times, there was no problem at all, and a good mold release effect was confirmed.

[Embodiment 3] (i-C blank (i-beam) v
In the present invention, since the mold base material, the intermediate layer of TiN, and the hard carbon film were manufactured by the same method as in Example 1 above, the hard carbon film formed on the glass blank was The manufacturing method will be described in detail. In this example, an ion beam was used as in Example 2, and a hard carbon film formed on the surface of a glass blank was used. As the film forming apparatus, the IBD apparatus shown in FIG. 9 was used.

First, the same Pb-free SF6 (S-NPH1) glass material as in Example 1 was washed in advance to remove dirt and dust, and then the glass blank fixing jig 3 shown in FIG.
7, the inside of the vacuum chamber 30 was depressurized to 4 × 10 ⁻³ Pa.

Next, after introducing argon gas into the ionization chamber at 10 sccm from the gas introduction port 33 to ionize it, a voltage of 500 V is applied to the ion beam extraction grid to extract the ion beam, and both surfaces of the glass material are irradiated for 5 minutes. Then, the surface of the glass blank was washed. Next, the pressure inside the vacuum chamber was reduced to 4 × 10 ⁻³ Pa again, and then methane gas was introduced into the ionization chamber at 10 sccm and hydrogen gas at 20 sccm. Then, after ionizing at a vacuum of gas pressure of 3.5 × 10 ⁻² Pa, an ion beam was extracted at an accelerating voltage of 10 kV and irradiated on the molding surface to form a hard carbon film of 30 nm.

Next, as in Example 1, press molding was carried out using an optical element molding die coated with a hard carbon film. As a result, the same effects as in Example 1 were observed, the molding surface of the mold member after molding 1000 times and the surface roughness of the molded optical element, and the releasability between the mold member and the molded optical element. Was good. In particular, when the molding surface of the mold member was observed with an optical microscope or a scanning electron microscope (SEM), defects such as scratches and cracks, reaction deposits of glass components, and glass fusion did not occur. Further, as a result of producing the respective optical element molding molds whose optical element shapes are a biconcave lens, a convex meniscus lens, and a concave meniscus lens by the same method as the above, it is not possible to obtain with a conventional hard carbon film coating mold, it is better Releasability was confirmed. In particular, in the case of the convex meniscus lens as shown in FIG. 8, in the case of the conventional hard carbon film, the optical element may not be released from the mold up to 350 ° C. However, the optical element molding mold of the present invention was used. In this case, stable mold release at 530 ° C. was possible. Similar to the biconvex lens described in the first half of Example 1, there was no problem in continuous molding of the above-mentioned various shapes even if molding was performed 1000 times.

The lanthanum-based glass (La
K12) and crown type glass (SK12) were molded, but the mold durability was dramatically better than that of the above flint type, and 300
Even if molding was performed 0 times, there was no problem at all, and a good mold release effect was confirmed.

Example 4 (Carbon Ion Implantation Blank vs i-C / TiN / Cemented Carbide) In the present invention, the mold base material, TiN as the intermediate layer, and hard carbon film are produced by the same method as in Example 1 above. Therefore, the method for producing the hard carbon film formed on the glass blank will be described in detail. The present invention uses a high-acceleration ion beam and uses a carbon ion-implanted glass blank in which carbon is ion-implanted on the surface of the glass blank. Ion implantation is shown in Figure 9.
The IBD device shown in was used.

First, the same Pb-free SF6 (S-NPH1) glass material as in Example 1 was washed in advance to remove dirt and dust, and then the glass blank fixing jig 3 shown in FIG.
7, the inside of the vacuum chamber 30 was depressurized to 4 × 10 ⁻³ Pa.

Next, argon gas is introduced from the gas inlet 33.
After introducing into the ionization chamber at 10 sccm for ionization,
Applying a voltage of 500V to the on-beam extraction grid
To draw out the ion beam, and on both sides of the glass material for 5 minutes
Irradiation was carried out to clean the surface of the glass blank. Then true
4 × 10 in the empty tank again^-3After decompressing to Pa, meta
Gas was introduced into the ionization chamber at 10 sccm. Soshi
And gas pressure 3.5 × 10 ^-2Ionized at a vacuum of Pa
Extraction of ion beam at post-acceleration voltage of 30 kV and molding surface
To form an ion-implanted layer having a thickness of 80 nm.

Next, as in Example 1, press molding was performed using an optical element molding die coated with a hard carbon film. As a result, the same effects as in Example 1 were observed, the molding surface of the mold member after molding 1000 times and the surface roughness of the molded optical element, and the releasability between the mold member and the molded optical element. Was good. In particular, when the molding surface of the mold member was observed with an optical microscope or a scanning electron microscope (SEM), defects such as scratches and cracks, reaction deposits of glass components, and glass fusion did not occur. Further, as a result of producing the respective optical element molding molds whose optical element shapes are a biconcave lens, a convex meniscus lens, and a concave meniscus lens by the same method as the above, it is not possible to obtain with a conventional hard carbon film coating mold, it is better Releasability was confirmed. In particular, in the case of the convex meniscus lens as shown in FIG. 8, in the case of the conventional hard carbon film, the optical element may not be released from the mold up to 350 ° C. However, the optical element molding mold of the present invention was used. In this case, stable mold release at 530 ° C. was possible. Similar to the biconvex lens described in the first half of Example 1, there was no problem in continuous molding of the above-mentioned various shapes even if molding was performed 1000 times.

The lanthanum-based glass (La
K12) and crown type glass (SK12) were molded, but the mold durability was dramatically better than that of the above flint type, and 300
Even if molding was performed 0 times, there was no problem at all, and a good mold release effect was confirmed.

[0037]

As described above, according to the method of molding an optical element of the present invention, a carbon film is provided on the surface of a glass material, and this is molded with an optical element molding die having a hard carbon film formed thereon. As a result, we succeeded in solving the following problems.

First, from the initial shot of optical element molding, about 2
The state in which the mold releasability that occurs up to 0 shots is poor can be changed from the initial molding shot to the good mold release state. As a result, the molding cycle time can be shortened, the number of products produced per hour can be improved, and the damage to the mold that occurs when the mold releasability is poor can be suppressed as much as possible.

Secondly, by using the optical element molding die according to the present invention, the releasability is improved even in the case of the convex meniscus lens shape which is difficult to be released by the conventional hard carbon film. As a result, even if the shape required cooling to 300 ° C after the completion of press molding, it is possible to release the mold at 500 ° C or higher, and it is possible to dramatically reduce the molding cycle time.

Thirdly, in the conventional hard carbon film type, the carbon film was consumed during molding and the glass material (P
By coating the glass blank itself of b-free SF6) with a carbon film, it was possible to suppress the consumption of the hard carbon film type as much as possible.

By using the optical element molding method according to the present invention, it is possible to improve productivity and reduce costs.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of an optical element molding die according to the present invention, showing a state before press molding.

FIG. 2 is a cross-sectional view showing an example of an optical element molding die according to the present invention, showing a state after press molding.

FIG. 3 is a schematic view showing an ion beam film forming apparatus used in an example of the present invention.

FIG. 4 is a diagram showing a depth profile by photoelectron spectroscopy (XPS) of a mixing layer formed between an intermediate layer of an optical element molding die according to the present invention and a hard carbon film.

FIG. 5 is a schematic view showing a high frequency discharge type film forming apparatus used in an example of the present invention.

FIG. 6 is a graph showing a result of infrared spectroscopic analysis (FTIR) of a hydrocarbon film formed on a molding surface according to the present invention by a high frequency discharge method.

FIG. 7 is a cross-sectional view showing a lens molding apparatus using the optical element molding die according to the present invention.

FIG. 8 is a cross-sectional view showing an example of an optical element molding die according to the present invention, showing a state before press molding.

FIG. 9 is a schematic view showing an ion beam film forming apparatus used in an example of the present invention.

[Explanation of symbols]

 1 Type Base Material 2 Intermediate Layer 3 Hard Carbon Film 4 Glass Material 5 Hydrocarbon Film 6 Optical Element 7 Vacuum Chamber 8 Ion Beam Device 9 Ionization Chamber 10 Gas Inlet 11 Ion Beam Extraction Grit 12 Ion Beam 13 Type Base Material 14 Substrate Holder And heater 15 exhaust port 16 vacuum chamber 17 exhaust port 18 heating heater 19 heater power source 20 glass material support 21 bias power source 22 glass material 23 high frequency applying antenna 24 matching circuit 25 high frequency power source 26 gas introducing pipe 30 vacuum chamber 31 ion beam Equipment 32 Ionization chamber 33 Gas inlet 34 Ion beam extraction grit 35 Ion beam 36 Ion beam blocking wall 37 Glass blank fixing jig 38 Exhaust port 39 Exhaust port 51 Vacuum tank 52 Vacuum tank lid 53 Upper mold 54 Lower mold 55 Upper mold Foot 5 6 Cylinder type 57 type holder 58 Heater 59 Push-up bar that pushes up the lower die 60 Air cylinder 61 Oil rotary pump 62, 63, 64 Valve 65 Inert gas introduction valve 66 Valve 67 Leak pipe 68 Valve 69 Temperature sensor 70 Water cooling pipe 71 Vacuum tank Stand to support

Front page continuation (72) Inventor Masaki Omori 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Nao Miyazaki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (8)

[Claims] 1. A method for press-molding an optical element made of glass, wherein the glass blank surface is covered with a carbon film, and the molding surface of an optical element molding die is made of a hard carbon film. Molding method. 2. The method for molding an optical element according to claim 1, wherein the carbon film covering the surface of the glass blank is a hydrocarbon film. 3. The method for molding an optical element according to claim 1, wherein the carbon film covering the surface of the glass blank is a hard carbon film. 4. The method for molding an optical element according to claim 1, wherein the hydrocarbon film covering the surface of the glass blank is a film formed by a plasma CVD method. 5. The method for molding an optical element according to claim 2, wherein the hydrocarbon film covering the surface of the glass blank is a film formed by an ion beam film forming method. 6. The method of molding an optical element according to claim 2, wherein the hydrocarbon film covering the surface of the glass blank is a film formed by implantation of carbon ions. 7. The method for molding an optical element according to claim 3, wherein the hard carbon film covering the surface of the glass blank is a film formed by an ion beam film forming method. 8. The method of molding an optical element according to claim 1, wherein the hard carbon film on the molding surface is a film selected from diamond, a diamond-like thin film, and a hydrogenated amorphous carbon film.