JP2002338262A - Optical element and method for forming the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare a mold releasing film adaptable to active glass rich in TiO2 and Nb2 O5 , such as high refractive index lead-free SF glass. SOLUTION: The surface of glass is irradiated and coated with a CH film. The resulting glass causes neither fusion bonding nor cracking in forming. The reason is considered that a tough film of O=Si-CH is formed on the surface of the glass by the irradiation to ensure mold releasability peculiar to CH even in the case of the above active glass.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an optical glass element, and more particularly to an optical glass element which does not require a polishing step after press molding and a method for molding the same.

[0002]

2. Description of the Related Art In recent years, there has been a tendency for optical glass lenses to have an aspherical surface that can simultaneously achieve both simplification of the lens configuration of an optical device and reduction in the weight of the lens portion. In the production of this aspherical lens, the direct press molding method is considered promising in terms of workability and mass productivity in the optical polishing method which is a conventional optical lens production method.

[0003] The direct press molding method is to heat a mass of optical glass on a non-spherical mold having been finished to a desired surface quality and surface accuracy in advance, or a mass of glass that has been heated in advance. This is a method of manufacturing an optical lens by press-molding an object, and after press-forming, does not require any further polishing or polishing step.

However, the above-mentioned method for producing an optical glass lens must be excellent to such an extent that the image forming quality of the obtained lens after press molding is not impaired. Particularly, in the case of an aspherical lens, it is required that the lens can be molded with high precision. Further, in consideration of mass productivity, it is required that the mold and the glass at a high temperature have good releasability and can be produced with a short tact.

[0005] Accordingly, the optical element molding material used in the above-mentioned manufacturing method is that the chemical action on glass at a high temperature is minimal, that the glass press surface of the mold is not easily damaged by abrasion, etc. It is necessary that the adhesion between the mold and the glass is low.

As optical element molding materials satisfying the conditions necessary for press molding of optical glass elements as described above to a certain extent, Japanese Patent Publication No. 7-45329 (blank CH coat) and Japanese Patent Publication No. 7-45330 (blank) CH & Glass coat) and JP-A-4-362029 (CH coat on ball blank) have been proposed.

[0007]

However, the conventional method described above has no effect on glass containing high concentrations of TiO ₂ or Nb ₂ O ₅ such as high refractive index lead-free SF glass. However, there is a disadvantage that fusion occurs during molding.

The reason for this is that, when TiO ₂ is taken as an example, the atmosphere at the time of molding is a nitrogen atmosphere or the like.
Oxygen in the O bond is reduced and eliminated (holes are generated), and lattice defects are generated, and at the same time, titanium ions are changed from tetravalent to trivalent, whereby the glass surface becomes extremely active. Conceivable.

In particular, when a carbon-based release film such as CH is used, carbon reacts with the above-described desorbed oxygen at the very beginning of molding and is consumed, so that carbon is not melted without exhibiting a desired release effect. Wearing occurs.

Even when fusion does not occur, since the adhesion between the mold and the glass is not sufficiently low, the glass element molded from the mold at a relatively high temperature in order to shorten the production tact time can be removed from the mold. When the lens is forcibly taken out, the molded product may be broken. Further, since the adhesion between the mold and the glass is relatively high, the molded product may be broken due to thermal stress caused by a difference in thermal expansion between the two in the cooling process after molding depending on the shape of the lens.

SUMMARY OF THE INVENTION In view of the above problems, the present invention provides an optical element molding material capable of molding an optical glass element having good optical performance and high accuracy by a short tact by a direct pressing method of optical glass. It is an object. Further, a second object of the present invention is to form an optical element which can be formed even in a glass containing a high concentration of TiO ₂ or Nb ₂ O ₅ , such as a high-refractive-index lead-free SF glass, without causing fusion during molding. Is to provide a way.

[0012]

According to the present invention, it has been found that this activity can be suppressed by irradiating the glass and then coating the surface of the glass to be molded with CH.

The reason why the above activity is suppressed is that the bond of O—Si is broken by irradiation to generate a dangling bond of —Si≡O, and when the glass in this surface state is coated with CH, the O—Si— A bond of CH and O = Si-CH is formed. In this case, CH is not attached to the glass but chemically bonded, so it is difficult to peel off,
In addition, since it is difficult to react with desorbed oxygen generated from Ti,
The original release effect is exhibited until the molding step is completed.

[0014] Further, the bonding portion of O = Si-CH is bonded to the released oxygen, and the amount of the released oxygen itself is reduced.

The thickness of the coating is 0.5 nm to
900 nm is suitable. That is, if the thickness is less than 0.5 nm, the effect of the film is not sufficient. If the thickness is more than 900 nm, the film is broken at the time of molding, and the glass component to be molded exudes to the surface, and the effect is lost.

In the present proposal, the irradiation treatment includes light (laser), plasma (positive and negative ions), electromagnetic waves (electrons).
Irradiation, specifically, CO ₂ laser irradiation,
Ar ion irradiation, electron beam irradiation and the like can be mentioned.

It is desirable that the above-mentioned film be peeled off after molding by a chemical method (eg, acid treatment, alkali treatment, heat combustion in an oxidizing atmosphere) or a physical method (eg, finish polishing, oxygen plasma treatment). Depending on the film thickness, the optical performance of the lens is not significantly degraded, so that the lens can be used without being peeled off.

The following is a detailed description corresponding to each claim.

A first invention according to the present invention relates to a method for manufacturing an optical element by housing an optical element molding material made of glass in a molding die and press-molding the same under heating. A glass optical element and a method for molding the glass optical element, which are obtained by subjecting an optical element molding material coated with a hydrocarbon film to press molding by molding after irradiation treatment.

In the above structure, the O-Si bond on the glass surface is broken by the irradiation treatment to generate a dangling bond of -Si≡O, and when the glass in this surface state is coated with CH, O-Si-CH And O = Si-CH bonds are formed. In this case, CH is not attached to the glass but chemically bonded to the glass, so that it is difficult to be peeled off and hardly reacts with the released oxygen generated from Ti. Shows type effect.

Further, the bonding portion of O = Si-CH is bonded to the released oxygen, and the amount of the released oxygen itself is reduced.

Therefore, it is important as an optical element molding material used in the optical glass element manufacturing method that the chemical action on glass at a high temperature is minimal, the adhesion between the mold and the glass is low, and there is no contamination on the mold. That is, even if the glass contains a high concentration of TiO ₂ or Nb ₂ O ₅ such as a high refractive index lead-free SF glass, fusion of the mold and the glass does not occur.

Next, a second invention according to the present application is the glass optical element according to claim 1, wherein the thickness of the coating is 0.5 to 900 nm. .

The thickness of the coating is 0.5 nm to 90 nm.
0 nm is suitable. That is, if the thickness is less than 0.5 nm, the effect of the film is not sufficient. If the thickness is more than 900 nm, the film is broken at the time of molding, and the glass component to be molded exudes to the surface, and the effect is lost. It takes a great deal of time to do so, which is not preferable.

A third invention according to the present application is characterized in that the irradiation treatment is at least one selected from irradiation of light (laser), plasma (positive and negative ions), and electromagnetic waves (electrons). Item 2 is a glass optical element according to Item 1 and a method for molding the same.

In the above configuration, it is a necessary condition that the O-Si bond on the glass surface is broken by the irradiation treatment to generate a dangling bond of -Si≡O. Fulfill. Further, the above-described irradiation processing is selected from the viewpoint of the availability of the irradiation processing apparatus and the cost.

According to a fourth aspect of the present invention, there is provided the glass optical element according to the first aspect, wherein the coating is peeled off after molding.

In the above structure, a CH film is present on the surface of the molded article after molding, but it is necessary to peel off the CH film depending on the use of the lens. Of course, depending on the application,
In some cases, it is not necessary to remove the film, or a multilayer antireflection film having the above-mentioned film as the first layer can be designed without peeling.

According to a fifth aspect of the present invention, there is provided the fourth aspect of the present invention.
3. The glass optical element according to claim 1 or 2, wherein the peeling is performed by a chemical method or a physical method, or a combination of two methods. .

To remove the CH film on the surface of the molded product, a solution having an action of dissolving the CH film, for example, a strong acid (hydrochloric acid, nitric acid,
Slightly polishing the lens surface with a chemical method such as a method of immersing the molded product in a strong alkali (KOH, NaOH) or a high concentration of a surfactant, a method of burning and removing CH by heating in an atmosphere containing oxygen, etc. And a physical method such as an oxygen plasma treatment. Also, by using these together, the CH film can be more efficiently peeled off.

According to the present invention, it is possible to obtain an optical element molding material which satisfies all of the above-mentioned requirements which could not be realized by the conventional surface treatment of an optical element molding material. By using
The optical glass element can be formed by directly pressing.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for manufacturing an optical element according to the present invention will be described below with reference to the drawings.

A cemented carbide having a diameter of 16 mm and the materials shown in Table 1 were processed into a pair of optical glass lens press-molding dies having a concave press surface with a curvature radius of 10 mm.

[0034]

[Table 1]

The press surfaces of these molds were polished to a mirror surface using diamond particles of 0.1 μm. Next, an alloy film shown in Table 1 was formed on the mirror surface by a sputtering method. A diagram of the mold is shown in FIG.

Next, an optical element molding material used for the test was manufactured. The glass is borosilicate glass SK12 (nd =
1.58313, vd = 59.4, transition point Tg = 550
° C, yield point At = 588 ° C, composition shown in Table 2) and lanthanum-based glass LaK12 (nd = 1.677790, νd
= 55.3, transition point Tg = 554 ° C, yield point At = 59
6 ° C., see Table 3 for composition) and high refractive index lead-free SF glass (1), (2), (3) [(1): nd = 1.808
09, νd = 22.8, transition point Tg = 552 ° C., yield point At = 589 ° C., (2): nd = 1.80518, νd
= 25.4, transition point Tg = 604 ° C., yield point At = 63
0 ° C., (3): nd = 1.80645, vd = 24.
4, the transition point Tg = 503 ° C., the sag point At = 538 ° C., and the composition is shown in Table 4.]

[0037]

[Table 2]

[0038]

[Table 3]

[0039]

[Table 4]

After performing various irradiation treatments on the ball lens, a CH film was formed (see FIG. 4). For comparison, a hydrocarbon film (CH film) was formed without performing irradiation treatment. The applied irradiation treatment is shown in Table 5, and the method of forming the CH film is shown below.

[0041]

[Table 5]

Formation of hydrocarbon film (CH film): The thickness of the hydrocarbon film is 1.5 to 50 nm. The hydrocarbon film can be formed using a simple thin film deposition technique such as plasma processing or ion gun processing. The atomic ratio of carbon: hydrogen in the hydrocarbon coating is, for example, 10/6 to
10 / 0.5.

FIG. 3 is a schematic diagram showing a schematic configuration of a hydrocarbon film deposition apparatus used for manufacturing the optical element molding material. Hereinafter, a method for applying a hydrocarbon film to the surface of the optical element molding material will be described with reference to this drawing.

In FIG. 3, reference numeral 112 denotes a vacuum chamber,
Reference numeral 14 denotes an exhaust port formed in the vacuum chamber. The exhaust
The port is connected to a vacuum exhaust source (not shown). 116 is above
At the gas inlet for introducing gas into the vacuum chamber 112
is there. The gas inlet is connected to a gas source (not shown).
You. In the vacuum chamber 112, a mold holding mold is provided at an upper part.
Holder 122, heater 124 for heating the mold
And a quartz film thickness monitor 126 for measuring the coating thickness are provided.
Have been. 128 is a high frequency application antenna. still,
130 is a mold held by the holder 122.
When applying a hydrocarbon film to the surface of the mold 130,
Evacuation is performed from the exhaust port 114, and the pressure in the vacuum chamber 112 is reduced.
After that, the hydrocarbon gas is supplied from the gas inlet 116, for example.
If 5 × 10 ^-2~ 5 × 10^-4Lead until Torr
And the antenna 128 for high frequency application
Applying high frequency of 500W to form hydrocarbon plasma
I do. As a hydrocarbon gas introduced into the vacuum chamber 112
Is, for example, methane, ethane, propane, ethylene,
Lopyrene, acetylene and the like can be exemplified. Hydrocarbon coating
Atomic ratio of carbon: hydrogen varies with deposition conditions
Therefore, set the conditions so that the desired atomic ratio is obtained.
Was.

Next, using the ball lens obtained as described above as a molding material, an optical element was molded using the mold shown in Table 1 above.

FIG. 2 schematically shows the apparatus used for the molding test. In FIG. 2, 24 is a chamber, 25 is an upper shaft, 26
Is a lower shaft, 27 is a block having a built-in heater (heater block), 28 is a heater block, 29 is an upper die,
0 is a lower mold, 31 is glass, and 32 is a hydraulic cylinder.

After the chamber 24 was evacuated by a vacuum pump (not shown), N ₂ gas was introduced,
After the inside of the heater block 4 is set to the N ₂ atmosphere, the heater blocks 27 and 2
8, the upper mold 29 and the lower mold 30 are heated and the temperature [SK1] corresponding to 10￣9 d · Pa · s in the viscosity of the glass to be formed.
2: 630 ° C, LaK12: 615 ° C, high refractive index lead-free SF glass (1): 645 ° C, (2) 660 ° C,
(3) At 580 ° C.], the upper shaft 25 was pulled up by the hydraulic cylinder 32, and the molding material (ball lens) was placed on the lower die 30 by an automatic hand (not shown). After holding for 1 minute at the mold temperature as it was, the upper shaft 25 was lowered by the hydraulic cylinder 32, and the ball lens was pressed by the upper mold 29 and the lower mold 30 with a force of 3,000 N for 3 minutes.
Thereafter, cooling was performed at 70 ° C./min, and when the upper and lower mold temperatures became lower by 10 ° C. than the Tg of each glass, the upper mold 29 was cooled.
Was raised, and the molded product 31 on the lower die 30 was taken out by an automatic hand (not shown). Subsequently, the molded product 31 was taken out of the chamber 24 through a replacement device (not shown). The upper and lower molds were heated again, and the above operation was repeated to perform 5,000 shot molding.

The molding results of 5,000 shots are shown in Table 4 above.
Shown in In Examples 1 to 3 of the present invention, good moldability was obtained in all the molds.

On the other hand, those coated with a hydrocarbon coating without irradiation treatment have a high glass adhesion, and are 10 times higher than Tg.
If the temperature is lower than ℃, the lens cannot be removed from the mold,
When I took it out forcibly, the lens broke. In some cases, the film on the surface of the mold stuck to the broken lens. When the mold was released after cooling to a temperature 100 ° C. lower than Tg, there was no problem with mold release (only borosilicate glass SK12 and lanthanum-based glass LaK12; high refractive index lead-free SF glass (1), (2) ),
However, in the case of (3), fusion occurred), but the molding condition was remarkably increased in tact, and mass production was not achieved. In addition, if the glass surface is not attached, the releasability is still worse, and the temperature is 10 ° C. higher than Tg.
When the mold was opened at a low temperature, the lens cracked and a part of the lens stuck to the mold and fused. The temperature at which the mold was stably released was found to be sufficient to cool to a temperature 200 ° C. lower than Tg (only borosilicate glass SK12 and lanthanum-based glass LaK12. High refractive index lead-free SF)
Glass (1), (2), and (3);
When the lens was scratched at about 0 shot, the lens was found to be scratched. When the mold was taken out and examined, it was found that the glass had abrasion that was thought to have occurred when the glass was deformed.

Also, in the case of the film of the present invention, if the film thickness is smaller than 0.5 nm, the same result as that obtained when nothing is attached to the glass surface is obtained. Cracking or sticking to the mold occurred, resulting in NG. These results were common to all the mold members shown in Table 1 above.

As described above, when the CH film is not formed after the irradiation treatment of the present invention is performed, the releasability is deteriorated and the Tg is reduced by 1 to
It became difficult to open the mold at a temperature lower by 0 ° C. and take out the molded product.
It is necessary to lower by 00 ° C. (only borosilicate glass SK12 and lanthanum-based glass LaK12. Lead-free high refractive index S
F glass (1), (2), and (3) suffered fusion), and the tact was significantly deteriorated, and the mold was deteriorated (scratched) during further molding.

For a very reactive glass containing a high concentration of TiO ₂ or Nb ₂ O ₅ , such as a lead-free high refractive index SF glass, in the conventional method, the mold release temperature should be reduced no matter how much. No effect was obtained, and only the CH film applied after the irradiation treatment of the present invention could be molded favorably.

It should be noted that the irradiation treatment shown in the text is only an example, and the bonding of O-Si on the glass surface is broken and -Si≡
Any process may be used as long as dangling bonds of O are generated.

The CH film on the surface of the molded article could be easily removed by immersing the molded article in a strong alkali + surfactant for 30 minutes.

[0055]

As described above, according to the first aspect of the present invention,
By applying CH coating after irradiation treatment of the optical element molding material, the adhesion between the CH film and the glass is enhanced, the CH film's original release property improving effect is exhibited, and further, like the high refractive index lead-free SF glass This has the effect of suppressing the reactivity of glass having a very high reactivity containing a high concentration of TiO ₂ or Nb ₂ O ₅ .

Accordingly, the present invention provides a material for press-molding optical glass which satisfies all the above-mentioned requirements as a material for optical glass molding, and manufactures high-precision glass elements in a large amount with an extremely short tact. It is extremely effective for. In addition, with respect to a glass having a very high reactivity containing a high concentration of TiO ₂ or Nb ₂ O ₅ , such as a high refractive index lead-free SF glass, the effect of the conventional method can be reduced even if the mold release temperature is lowered. Instead, only the present invention is effective.

Next, according to the second aspect of the present invention, since the thickness of the CH film is set to 0.5 to 900 nm, there is an effect that the above-mentioned effects can be favorably obtained.

Further, according to the third aspect of the present invention, since the irradiation treatment can be effectively performed at low cost, the above-mentioned effects can be obtained well.

According to the fourth aspect of the present invention, since the coating is peeled off after molding, the lens performance of the molded article is not deteriorated by the method of the present invention.

According to the fifth aspect of the present invention, the peeling described in claim 4 can be easily peeled off by a chemical method, a physical method or a combination of the two, and the cost increase can be minimized. Can be kept to a minimum.

As described above, the present invention provides a material for press-molding an optical glass which satisfies all the necessary conditions as a material for molding an optical glass. This is extremely effective for mass-producing high-precision optical glass elements from glass in a very short tact.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a mold used in a first embodiment of the present invention.

FIG. 2 is a schematic sectional view of a press forming apparatus for an optical element.

FIG. 3 is a schematic diagram showing a schematic configuration of a hydrocarbon film deposition apparatus.

FIG. 4 is a schematic sectional view showing an optical element molding material used in the first embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 type base material 2 type surface protective film 24 chamber 25 upper shaft 26 lower shaft 27 heater block 28 heater block 29 upper die 30 lower die 31 glass 32 hydraulic cylinder 112 vacuum chamber 114 exhaust port 116 gas introduction port 122 dome shaped holder 124 heater 126 Quartz film thickness monitor 128 High frequency application antenna 130 Optical element molding material 131 CH film

Claims (5)

[Claims] 1. A method of manufacturing an optical element by housing an optical element molding material made of glass in a molding die and press-molding the material under heating, wherein the surface of the molding material is irradiated with a hydrocarbon film. A glass optical element and a method for molding the optical element, which are obtained by press-molding an optical element molding material coated with a resin. 2. The coating according to claim 1, wherein said coating has a thickness of 0.5 to 900 nm.
The glass optical element according to claim 1, and a molding method thereof. 3. The glass optical element according to claim 1, wherein the irradiation treatment is at least one selected from irradiation of light (laser), plasma (positive and negative ions), and electromagnetic waves (electrons). And its molding method. 4. The glass optical element according to claim 1, wherein the coating is peeled off after molding. 5. The glass optical element according to claim 1, wherein the peeling according to claim 4 comprises a chemical method or a physical method, or a combination of two methods.