JPH0729786B2 - Mold for optical element molding - Google Patents

Description

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

[Prior Art] The technology of manufacturing a lens by press molding of a glass material without the need for a polishing step eliminates the complicated steps required in the conventional manufacturing of a lens, and allows a lens to be manufactured simply and inexpensively. It has become possible and has recently 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, mold releasability and mirror surface workability. Conventionally,
As this type of mold material, many proposals have been made on metals, ceramics, materials obtained by coding them, and the like.
To give some examples, JP-A-49-51112 discloses 13Cr.
Martensitic steel is disclosed in JP-A-52-45613 as SiC and Si ₃ N ₄
However, JP-A-60-246230 proposes a material in which a cemented carbide is coated with a noble metal, and JP-A-61-183134 proposes a material in which a diamond thin film or a diamond-like carbon film is coated.

[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 temperatures, oxidation also occurs and a SiO ₂ film is formed on the surface, causing fusion with glass, and because of its higher 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.

Also, the film called a diamond-like carbon film is not limited to one type, and is composed of only carbon, but the bond type is an amorphous film composed of sp, sp ² , sp ³ hybrid,
Micrographite aggregates, amorphous film containing hydrogen atoms in addition to carbon atoms (hydrogenated amorphous carbon film, abbreviated as aC: H film below), minute diamonds and minute graphite, and the structure of both amorphous There is a film containing it. In addition, sp, sp ² ,
If the ratio of sp ³ is the size of graphite, is the ratio of hydrogen and carbon, and is the ratio of crystalline and amorphous, the properties of the film are different. The diamond-like carbon film disclosed in Japanese Patent Laid-Open No. 61-183134 has no description on this point, and only describes that it was formed by ion beam sputtering. Generally, in graphite ion beam sputtering, a film is formed. However, it contains many multiple bonds like the membrane of
Or the multiple bond is delocalized and the conjugated system is long,
The film containing graphite microcrystals is more likely to reduce lead oxide, which is a component of glass, than the film of, so that lead deposition occurs and the mold durability decreases, and the surface accuracy of the optical element decreases. There is a drawback.

Therefore, an object of the present invention is to provide an optical element molding die suitable for molding an optical element of glass, and in particular, does not cause fusion with glass at a high temperature, can be mirror-polished, and has an appropriate hardness. It is intended to provide a mold for molding an optical element, which has the following characteristics, is hard to be oxidized, and does not cause precipitation of lead.

[Means for Solving the Problems] In an optical element molding die used for press-molding an optical element made of glass according to the present invention, an intermediate layer or a base material made of a carbide as a base material component is formed on at least a molding surface of a mold base material. Provided is an optical element molding die, which is characterized in that an aC: H film is coated through an intermediate layer composed of a component and aC: H.

As the mold base material, a material containing a component element capable of forming a carbide is preferable, and examples thereof include cemented carbide (containing WC as a main component), SiC, AlN, cermet and the like.

The a-C: H film coated on at least the molding surface of the mold base material, that is, the surface in contact with the glass is (1) an intermediate layer made of a carbide of the base material component, or (2) It is via an intermediate layer composed of a base material component and aC: H. In the present invention, the intermediate layer of the above (1) and (2) is a layer whose boundary with the aC: H film is clear, and in addition, the composition and structure are continuously changed.
-Includes a layer whose boundary with the C: H film is not always clear.

Even if the aC: H film contains diamond crystals,
It does not have to be, but it does not contain a graphite crystal layer, and has hardness, thermal stability, and more than glassy carbon and polymer films.
It is a carbon film having excellent chemical stability and includes a film generally called an i-carbon film.

The thickness of the intermediate layer is 10 to improve the adhesion between the mold and the film.
About 1000Å is preferable. If the thickness of the aC: H film is less than 50Å, the surface accuracy tends to be low, and
If it exceeds Å, the strain of the film tends to increase and the adhesion tends to decrease, so about 50 to 5000 Å is preferable.

As a method of coating the intermediate layer and the aC: H film on at least the molding surface of the mold base material, there are plasma vapor deposition method, ion beam vapor deposition method, plasma patcher vapor deposition method, plasma ion plating method, electron cyclotron resonance method, etc. Various PVD
Method, a CVD method can be used.

[Examples] Specific examples of the present invention will be described below with reference to the drawings.

Example 1 FIGS. 1 and 2 show an optical element molding die 1 according to the present invention.
2 illustrates one embodiment.

FIG. 1 shows the state of the press-molded surface of the optical element, and FIG. 2 shows the state after the optical element is molded. Figure 1 shows the mold base material, 2,
5 is an aC: H film formed on the molding surface of the glass material of the mold base material in contact with the intermediate layer, 3 is a glass material, and 4 in FIG. 2 is an optical element. By pressing the glass material 3 placed between the molds as shown in FIG.
As shown in the figure, the optical element 4 such as a lens is molded.

Next, a production example of the optical element molding die of the present invention will be described in detail. A schematic diagram of the apparatus used to form the aC: H film and the intermediate layer is shown in FIG.

In the figure, 11 is a vacuum container, 12 is an ion gun, 13 is a gas inlet,
Reference numeral 14 is a substrate, 15 is an exhaust port, 16 is tungsten, and 17 is an electron gun.

The mold base material was WC (90%) + Co (10%). Vacuum container 11
After depressurizing the inside to 1 × 10 ⁻⁶ Torr, Ar gas was introduced into the ion gun 12 through the gas inlet 13 to perform irradiation cleaning on the surface of the substrate (base material) 14 as an Ar ⁺ ion beam.

Then an intermediate layer was produced. Methane gas was introduced into the ion gun from the gas inlet, and the acceleration voltage was 100v and the ion current was 0.05mA / cm ^2.
Was applied to form an ion beam, while a high-purity (99.99%) Tungsten 16 was irradiated with an electron beam (9KV, 1A) from an electron gun 17 to perform simultaneous vapor deposition. The substrate temperature was kept at 300 ° C., and the pressure inside the vacuum container was 4 × 10 ⁻⁴ Torr. The generated intermediate layer was 1,000 liters.

Next, an aC: H film was formed. Introducing a proportion mixed gas to _{CH 4 / H 2 = 1/} 2 in the ion gun, the acceleration voltage applied to 600V, the substrate holding the ion beam of the ion current 0.85 mA / cm ² on the substrate temperature 0.99 ° C. (base material + (Intermediate layer).

The pressure was 2 × 10 ⁻⁴ Torr, and the aC: H layer had a film thickness of 5,000Å.

Next, an example in which a glass lens is press-molded by the optical element molding die according to the present invention will be described in detail. Table 1 below shows the types of mold materials used in the experiment.

Nos. 1 to 3 are comparative materials, and No. 4 is a material proposed by the present invention. The lens forming apparatus used is shown in FIG.

In FIG. 7, 51 is a vacuum chamber main body, 52 is a lid thereof, 53 is an upper mold for molding an optical element, 54 is a lower mold thereof, 55 is an upper mold holder for holding an upper mold, and 56 is a body mold. , 57 is a mold holder, 58
Is a heater, 59 is a lifting rod that lifts the lower die, 60 is an air cylinder that operates the lifting rod, 61 is an oil rotary pump,
Reference numerals 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.

First, adjust the flint type optical glass (SF14) to a predetermined amount, place the spherical glass material in the mold cavity,
This is installed in the device.

After placing the mold into which the glass material was placed in the equipment, vacuum chamber
The lid 52 of 51 is closed, water is flowed through the water cooling pipe 70, and the heater 58
Pass a current through. 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. Air cylinder when the temperature reaches a certain level
Activate 60 and pressurize at 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, and 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 die is removed, and the molded product is taken out.

As described above, the flint optical glass SF148 (softening point S
(p = 586 ° C., dislocation point Tg = 485 ° C.) was used to mold the lens 4 shown in FIG. FIG. 9 shows the molding conditions at this time, that is, the time-temperature relationship diagram.

Next, the surface roughness of the molded lens and the surface roughness of the mold before and after molding were measured. The results are shown in Table 2.

Next, using the same mold for No. 1 and 4 that do not cause fusion,
After performing molding 0 times, the surface roughness was measured. The results are shown in Table 3.

As is clear from the results shown in Tables 2 and 3, the mold material according to the present invention has excellent releasability from glass, and even if it is repeatedly used, the surface deterioration is extremely small as compared with the conventional mold material.

Example 2 The same mold base material and apparatus as in Example 1 were used. After cleaning the substrate in the same manner, the pressure was kept at 4 × 10 ⁻⁴ Torr and the substrate temperature was kept at 150 ° C., methane gas was introduced into the ion gun, ion beam irradiation was carried out, and tungsten was vapor deposited at the same time.
At that time, the acceleration voltage of the ion gun and the current value of the electron beam for vapor deposition were changed as shown in Fig. 4, and the intermediate layer, aC: H
A total of 6,000Å layers were deposited in succession.

Next, an example in which the apparatus shown in FIG. 8 is used to press-mold a glass lens with the above mold will be described in detail.

In FIG. 8, 104 is an intake substitution chamber, 106 is a forming chamber, 108 is a vapor deposition chamber, and 110 is an ejection substitution chamber. Reference numerals 112, 114 and 116 are gate valves, 118 is a rail, and 120 is a pallet that can be conveyed on the race in the direction of arrow A. Reference numerals 124, 138, 140 and 150 are cylinders, and 126 and 152 are valves. A heater 128 is arranged along the rail 118 in the molding chamber 106.

Inside the molding chamber 106, a heating zone 106-1, a press zone 106-2, and a slow cooling zone 106-3 are sequentially arranged along the pallet conveying direction. In the press zone 106-2, the cylinder 138
An upper molding member 130 is fixed to the lower end of the rod 134, and a lower molding 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 according to the present invention shown in FIG.
In the vapor deposition chamber 108, a container 14 containing a vapor deposition substance 146 is placed.
2 and a heater 144 for heating the container are arranged.

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

Place glass blanks on pallet 120 and take in replacement chamber 1
It is put in the position 120-1 in 04, and the pallet at that position is pushed in the direction A by the rod 122 of the cylinder 124, and the gate valve 11
It is conveyed to the position 120-2 in the molding chamber 106 over 2 and thereafter, in the same manner, new intake and replacement chambers 104 are sequentially transferred at a predetermined timing.
Put the pallet inside and form the pallet every time.
Inside, they were sequentially transported to the positions of 120-2 → ・ ・ ・ ・ ・ → 120-8. In the meantime, in the heating zone 106-1, the glass blank is gradually heated by the heater 128 so as to have the softening point or lower at the position 120-4, and then conveyed to the press zone 106-2, where the cylinders 138 and 140 are operated. Upper mold member 130 and lower mold member 13
Press at 10 kg / cm ² for 5 minutes by 2 and then release the applied pressure and cool to below the glass transition point, and then operate the cylinders 138 and 140 to separate the upper mold member 130 and the lower mold member 132 from the glass molded product. Typed At the time of the pressing, the pallet was used as a body member for molding. After that, the glass molded product was gradually cooled in the slow cooling zone 106-3. The interior of the molding chamber 106 was filled with an inert gas.

The pallet that has reached the position 120-8 in the forming chamber 106 is passed through the gate valve 114 in the next conveyance and then stored in the vapor deposition chamber 108.
Transported to position 120-9. Usually, vacuum vapor deposition is performed here, but in the present embodiment, the vapor deposition was not performed. Then, in the next transportation, the material was transported beyond 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 150 was operated and the glass molded article was taken out of the molding apparatus 102 by the rod 148.

Table 4 shows the surface roughness of the molding surfaces of the mold members 130 and 132 before and after the above-described press molding, the surface roughness of the optical surface of the molded optical element, and the releasability between the molding optical element and the mold members 130 and 132. Show.

Next, with respect to Nos. 1 and 4 in which fusion did not occur, press molding was continuously performed 10,000 times using the same mold member. Mold member 130 at this time,
Table 5 shows the surface roughness of the molding surface of 132 and the surface roughness of the optical surface of the molded optical element.

As described above, in the examples of the present invention, it was possible to sufficiently maintain good surface accuracy even when used for repeated press molding, and to mold an optical element with good surface accuracy without causing fusion.

Example 3 A schematic diagram of the apparatus used is shown in FIG.

In the figure, 21 is a vacuum container, 22 is an ion gun, 23 and 23 'are gas inlets, 24 is a substrate, 25 is an exhaust port, 26 is tungsten, 27 is an electron gun, 28 is a matching box, 29 is a high frequency power supply. is there.

Using the same die base material as in Example 1, the substrate (base material) 24 was cleaned with an Ar ⁺ ion beam in the same manner. After that, methane gas from the gas inlet 23 into the ion 22 4 × 10 ^-3 To
The substrate was irradiated with an ion beam at an accelerating voltage of 100 V and an ion current of 0.05 mA / cm ² by introducing rr. Simultaneously, 4 × 10 ⁻⁴ Torr of argon gas was introduced from the gas introduction port 23 ′ in the vicinity of 99.99% high-purity tungsten 26, and tungsten was sputter-deposited by applying a high frequency of 13.56 MHz output of 1 kw. The substrate temperature was 150 ° C, and 1,000 Å of the intermediate layer was formed.

Next, an aC: H film was formed in the same manner as in Example 1, and the total film thickness including the intermediate layer was set to 6,000Å.

Using the optical element molding die thus obtained, Example 1
When a molding test was conducted using the apparatus shown in FIG. 7 in the same manner as in Example 1, good results were obtained as in the case of mold No. 4 of Example 1.

Example 4 Using the same die base material apparatus as in Example 3, the substrate was cleaned in the same manner. After that, methane gas was introduced into the ion gun and irradiation as an ion beam was performed. At the same time, tungsten was sputtered, but the high frequency output and the ion gun acceleration voltage were changed as shown in FIG. 6 to continuously form a film. The total film thickness was 5,500Å. Substrate temperature 150 ℃, Ar
Gas 4 × 10 ^-3 Torr → 0 Torr, high frequency (1356MHz) output 1kw →
0w, methane gas 4 × 10 ⁻⁴ Torr, acceleration voltage 50v → 500v.

Using the optical element molding die thus obtained, a molding test was conducted using the apparatus shown in FIG. 8 in the same manner as in Example 2. As a result, good results were obtained in the same manner as in Mold No. 4 in Example 2. .

EFFECTS OF THE INVENTION According to the present invention, an intermediate layer composed of a carbide of a mold base material component or a mold base material component and a-C: H is formed on a mold base material, and a-C: H is provided through the intermediate layer. By forming the H film, the film stress is relaxed in the intermediate layer, the strain due to thermal and mechanical deformation is relaxed, and the diffusion of the binder metal in the mold base material is prevented, so that it is contained in the glass. Metal, alkali element precipitation,
It was possible to obtain a molding die that did not cause glass fusion. Further, it was possible to obtain a molding die having excellent adhesion between the die base material and the film and excellent durability.

[Brief description of drawings]

1 and 2 are sectional views showing one embodiment of an optical element molding die according to the present invention. FIG. 1 shows a state before press molding, and FIG. 2 shows a state after press molding. FIGS. 3 and 5 are schematic views showing an apparatus used in the method of manufacturing the optical element molding die according to the present invention. Figures 4 and 6 show the main conditions that are changed when forming the intermediate layer, aC: H film. Figure 4 shows the relationship between ion gun acceleration voltage and electron gun current value with respect to film thickness, FIG. 5 is a diagram showing the relationship between ion gun acceleration voltage and high frequency output with respect to film thickness. 7 and 8 are sectional views showing a lens molding apparatus using the optical element molding die according to the present invention. FIG. 7 is a discontinuous molding type and FIG. 8 is a continuous molding type. FIG. 9 is a time-temperature relationship diagram at the time of lens molding. 1 ... Mold base material, 2 ... aC: H film, 3 ... Glass material, 4 ... Molded lens, 5 ... Intermediate layer, 11 ... Vacuum container, 12 ... Ion gun, 13 ... Gas inlet, 14 ... Substrate (base material), 15 ... Exhaust port, 16 ... Tungsten, 17 ...
… Electron gun, 21 …… Vacuum container, 22 …… Ion gun, 23,23 ′
Gas inlet, 24 ... Substrate (base material), 25 ... Exhaust port, 26 ...
… Tungsten, 27 …… electron gun, 28 …… matching box, 29 …… high frequency power supply, 51 …… vacuum tank body, 52 …… lid, 53 …… upper mold, 54 …… lower mold, 55 …… upper mold Hold, 56 ...
… Body type, 57 …… type holder, 58 …… heater, 59 …… raising rod, 60 …… air cylinder, 61 …… oil rotary pump,
62,63,64 …… valve, 65 …… inflow pipe, 66 …… valve, 67 …… outflow pipe, 68 …… valve, 69 …… temperature sensor, 70 …… water cooling pipe, 71 …… stand, 102… … Molding equipment, 1
04 …… Replacement chamber for intake, 106 …… Molding chamber, 108 …… Deposition chamber, 110 …… Replacement chamber for ejection, 112 …… Gate valve, 11
4 …… Gate valve, 116 …… Gate valve, 118 …… Rail, 120 …… Pallet, 122 …… Rod, 124 …… Cylinder, 126 …… Valve, 128 …… Heater, 130 …… Upper mold, 1
32 …… Lower mold, 134 …… Rod, 136 …… Rod, 138 ……
Cylinder, 140 ... Cylinder, 142 ... Vessel, 144 ... Heater, 146 ... Vapor deposition material, 148 ... Rod, 150 ... Cylinder, 152 ... Valve.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yasushi Taniguchi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Kiyoshi Yamamoto 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Within the corporation

Claims (1)

[Claims] 1. An optical element molding die used for press-molding an optical element made of glass, which comprises an intermediate layer made of carbide as a base material or a base material and hydrogenated amorphous carbon on at least the molding surface of a mold base material. Through the intermediate layer,
An optical element molding die characterized by being coated with a hydrogenated amorphous carbon film.