JP2002348127A - Optical element and method for moulding the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a blank coat capable of molding a glass having high concentrations of titanium oxide and niobium oxide such as a lead free SF glass having a high refractive index, for which an existing mold and a blank coat cannot be used due to occurrence of fusion bonding. SOLUTION: Reactivity of the glass surface is much lowered by attaching a transition metal oxide membrane on the surface of a blank. To put it concretely, the surface of the blank is coated with an oxide consisting of one (two) or more elements selectable from among Mn, Fe, Co, Ni, and (Cr).

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 above surface treatment of the conventional optical element molding material does not satisfy all of the above conditions. For example, the surface treatment (coating) materials described above have minimal chemical action on glass at high temperatures, but have the major disadvantage that they have a high coefficient of friction with the mold, and that the glass pressed surface of the mold during molding has scratches and the like. Because the mold is easily damaged and the adhesion between the mold and the glass is not sufficiently low, even if you try to remove the glass element molded from the mold at a relatively high temperature to shorten production tact, Is strongly adhered and cannot be taken out, and if it 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. Further, the above-described conventional method has no effect on glass containing high concentration of TiO ₂ or Nb ₂ O ₅ such as high-refractive-index lead-free SF glass, and has a disadvantage that fusion occurs during molding. there were.

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.

[0009]

In order to achieve the above-mentioned object, a first invention according to the present invention is to provide an optical element molding material made of glass in a molding die and press-mold the same under heating. In the method of manufacturing an optical element by performing, an optical element molding material in which the surface of the molding material is coated with an oxide composed of at least one element selected from Mn, Fe, Co, and Ni is press-formed by molding. A glass optical element and a molding method thereof.

In the above construction, M
The presence of an oxide composed of one or more elements selected from n, Fe, Co, and Ni significantly reduces the reactivity of the glass surface, thereby significantly reducing the adhesion to the mold and releasing the mold at a high temperature. It is possible to do. for that reason,
Manufacturing tact can be significantly shortened. Furthermore, there is no reactivity with glass. In addition, since there is no reactivity and the adhesion to the mold is low, the material does not adhere to the mold, and the coefficient of friction between the mold and the glass is reduced. It is hard to receive. Further, with the above-described configuration, 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, fusion does not occur during molding. The reason why a glass containing a high concentration of TiO ₂ or Nb ₂ O ₅ , such as a high refractive index lead-free SF glass, fuses with a mold is that, when TiO ₂ is taken as an example, the atmosphere during molding is a nitrogen atmosphere or the like. Therefore, oxygen of the Ti—O bond on the surface is reduced and eliminated (hole generation), and lattice defects are generated, and at the same time, titanium ions are changed from tetravalent to trivalent, which makes the glass surface extremely active. It is considered that the state becomes rich. In the present invention, it has been found that this activity can be suppressed by coating the surface of the glass to be formed with an oxide comprising at least one element selected from Mn, Fe, Co, and Ni.
The reason why the activity is suppressed is that the release of oxygen
It is considered that the generated holes are trapped by the transition metal ions and recombine.

Therefore, it is important as an optical element molding material used in an optical glass element manufacturing method 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. A glass that contains a high concentration of TiO ₂ or Nb ₂ O ₅ , such as a high-refractive-index lead-free SF glass, completely satisfies the conditions that the adhesion between the mold and the glass is low and there is no contamination to the mold. No fusion between the mold and the glass.

Next, a second invention according to the present application relates to a method for manufacturing an optical element by accommodating a material for molding an optical element made of glass in a molding die and press-molding under heating. Cr. On the surface of the material Mn, Fe, C
The present invention relates to a glass optical element formed by press-molding an optical element molding material coated with an oxide composed of two or more elements selected from o and Ni, and a molding method thereof.

[0013] In the above configuration, the surface of the molding material is C
r, Mn, Fe, Co. The presence of an oxide composed of two or more elements selected from Ni significantly reduces the reactivity of the glass surface, so that the adhesion to the mold is significantly reduced and the mold can be released at a high temperature. . Therefore, the manufacturing tact can be significantly reduced.
Furthermore, there is no reactivity with glass. Also, there is no reactivity,
In addition, since the adhesive force with the mold is low, the material does not adhere to the mold, and the coefficient of friction between the mold and the glass is reduced, so that the glass press surface of the mold is less susceptible to damage such as scratches.

Further, according to the above configuration, a high refractive index lead-free material is used.
High concentration of TiO such as SF glass ₂And Nb₂O₅Including
Even with the glass, the fusion does not occur during molding. High
High concentration of TiO such as refractive index lead-free SF glass₂And
Nb₂O₅The cause of the fusion of the glass containing the metal with the mold is T
iO₂For example, if the atmosphere during molding is a nitrogen atmosphere, etc.
Therefore, the oxygen of the Ti—O bond on the surface is reduced and released.
(Generation of holes), lattice defects are generated, and
Ion changes from tetravalent to trivalent, which
It is thought that the glass surface will be in an extremely active state
It is.

In the present invention, this activity is determined by using Cr, Mn, F
It has been found that it can be suppressed by coating the surface of the glass to be molded with an oxide composed of two or more elements selected from e, Co, and Ni. It is considered that the reason why the activity is suppressed is that the generated holes are trapped by the transition metal ions and recombine by the desorption of oxygen.

Therefore, it is important as an optical element molding material used in an optical glass element manufacturing method 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. A glass that completely satisfies the conditions that the adhesion between the mold and the glass is low and that there is no contamination to the mold, and further contains a high concentration of TiO ₂ or Nb ₂ O ₅ such as a high refractive index lead-free SF glass. However, fusion between the mold and the glass does not occur.

A third invention according to the present application is the glass optical element according to the first or second invention, wherein the coating has a film thickness of 10 to 900 nm, and a molding method thereof.

In the above structure, the thickness of the coating is 10
If the thickness is smaller than 900 nm, the above-mentioned effect is not sufficient, and
If the thickness is larger than that, it is not preferable because the film is easily peeled off, the film remains in the mold and the appearance of the molded product is deteriorated, and it takes a lot of trouble to remove the film from the molded product after molding.

A fourth invention according to the present application is the glass optical element according to the first or second invention, wherein the coating is peeled off after molding, and a molding method thereof.

In the above configuration, the surface of the molded article after the molding is coated with Cr, Mn, Fe, Co. There are oxides composed of one or more elements selected from Ni, but these need to be peeled off depending on the use of the lens. Of course, depending on the application, there is no need to peel off the film, and 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, in the method according to the first aspect, the peeling according to the fourth aspect comprises a chemical method or a physical method, or a combination of two methods. And a method for molding the glass optical element.

To remove the oxide film on the surface of the molded article, a solution having a function of dissolving the oxide, for example, a strong acid (hydrochloric acid, nitric acid, sulfuric acid), a strong alkali (KOH, NaOH), a high-concentration surfactant or the like There are a chemical method of immersing the molded article in the mold and a physical method such as polishing. In addition, by using these together, the oxide film can be more efficiently peeled off.

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

[0024]

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-forming dies having a concave pressing surface with a curvature radius of 10 mm.

[0026]

[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.]

[0029]

[Table 2]

[0030]

[Table 3]

[0031]

[Table 4]

Various transition metal oxide films were formed on the ball lens by vapor deposition (see FIG. 4). For comparison, a hydrocarbon film (CH film) was formed by the following method. Table 5 shows the formed films.

(Comparative Example) Deposition of a 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 carbon: hydrogen atomic ratio in the hydrocarbon coating is, for example, 10/6 to 10 / 0.5.

[0034]

[Table 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 results of molding at 5,000 shots are shown in Table 4 above.
Shown in In Examples 1 and 2 of the present invention, good moldability was obtained in all the molds.

On the other hand, the one coated with a hydrocarbon coating had a high glass adhesion, and the lens could not be removed from the mold at a temperature lower than Tg by 10 ° C., and when the lens was forcibly removed, the lens was broken. . In some cases, the film on the surface of the mold stuck to the broken lens. 1 than Tg
When the mold was released after cooling to a temperature lower by 00 ° C., the mold release came to be no problem (borosilicate glass SK12
And lanthanum glass LaK12 only. High refractive index lead-free SF glass (1), (2), (3) fusion occurs)
When the lens was scratched at about 1000 shots, the lens was found to be scratched. When the mold was taken out and examined, it was found that the mold had abrasions that appeared to have occurred when the glass was deformed. In addition, when the glass surface is not attached, the releasability is further deteriorated.
When the mold was opened at a temperature lower by 10 ° C., the lens cracked and a part of the lens was stuck to the mold and fused. When the temperature at which the mold was stably released was determined, it was found that cooling to 200 ° C. lower than Tg was sufficient (borosilicate glass S
Only K12 and lanthanum glass LaK12. The high refractive index lead-free SF glass (1), (2), and (3) caused fusing). After about 500 shots, the lens was found to be scratched. There was an abrasion on the mold that seemed to have occurred.

Also, in the case of the film of the present invention, when the film thickness is smaller than 10 nm, the same result as that obtained when nothing is attached to the glass surface, and when the film thickness is larger than 900 nm,
The film breaks during molding or sticks to the mold, causing NG
Met. These results were common to all the mold members shown in Table 1 above.

As described above, when the oxide film of the present invention is not formed, the mold releasability deteriorates, and it becomes difficult to open the mold at a temperature lower than Tg by 10 ° C. to remove the molded product. It is necessary to lower the Tg by 100 ° C. to 200 ° C. (borosilicate glass SK12 and lanthanum glass L
aK12 only. High refractive index lead-free SF glass (1),
(2) and (3), fusion occurred), 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 oxide film of the present invention was successfully formed.

It should be noted that the oxide films shown in the text are merely examples, and may be, for example, an oxide film obtained by combining these in a multilayer or an oxide film in which two or more kinds of oxides are simultaneously blown. Further, in the above embodiment, the film is formed by using the vacuum evaporation method. However, other methods such as sputtering, various methods of forming a film such as an evaporation method such as plasma CVD or an impregnation method or a coating method are appropriately used. A film can be formed.

The oxide 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.

[0047]

As described above, according to the first aspect of the present invention,
In a method of manufacturing an optical element by housing an optical element molding material made of glass in a molding die and press-molding under heating, the surface of the molding material has Mn, Fe, C
Since an optical element molding material coated with an oxide composed of one or more elements selected from o and Ni is press-molded by molding, it is an ideal method as a glass optical element and a molding method therefor.

That is, the present invention provides a material for press-molding optical glass which satisfies all the above-mentioned requirements as a material for molding optical glass, and is used for producing high-precision optical glass elements in a very short tact in large quantities. It is extremely effective. 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. However, only the oxide film of the present invention is effective.

Next, according to a second aspect of the present invention, there is provided a method for manufacturing an optical element by housing an optical element molding material made of glass in a molding die and press-molding under heating. Cr, Mn, Fe, Co,
Since an optical element molding material coated with an oxide composed of two or more elements selected from Ni is press-molded by molding, this is an ideal method as a glass optical element and a molding method therefor.

That is, the present invention provides a material for press-molding optical glass which satisfies all the above-mentioned requirements as a material for molding optical glass, and is used for producing a high-precision optical glass element in a large amount with an extremely short tact. It is extremely effective. 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. However, only the oxide film of the present invention is effective.

According to the third aspect of the present invention, since the thickness of the coating is set to 10 to 900 nm, there is an effect that 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 the fourth aspect can be easily peeled off because it comprises a chemical method or a physical method or a combination of the two.
Cost increase can be minimized.

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 tank 114 exhaust port 116 gas introduction slot 122 dome shaped holder 124 heater 126 Crystal thickness monitor 128 High frequency application antenna 130 Optical element molding material 131 Transition metal oxide film

Claims (5)

[Claims] 1. A method for manufacturing an optical element by accommodating an optical element molding material made of glass in a molding die and press-molding it under heating, the method comprising:
A glass optical element and a method for molding the glass optical element, wherein an optical element molding material coated with an oxide comprising at least one element selected from Mn, Fe, Co, and Ni is press-molded. 2. A method of manufacturing an optical element by accommodating an optical element molding material made of glass in a molding die and press-molding it under heating, the method comprising:
A glass optical element and a method for molding the glass optical element, wherein an optical element molding material coated with an oxide comprising two or more elements selected from Cr, Mn, Fe, Co, and Ni is press-molded by molding. 3. The glass optical element according to claim 1, wherein the coating has a film thickness of 10 to 900 nm. 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.