JP4307983B2 - Optical element molding die and optical element molding method - Google Patents

Description

The present invention, lenses, relates to an optical element such as a prism optical element molding method using the mold and this optical element molding for the manufacture by press molding of glass material.

  In recent years, as a method for producing an optical element from such a glass material, there is press molding using a molding die. Since this manufacturing method does not require polishing, it has an advantage that an optical element can be manufactured easily and inexpensively. Conventionally, there are various types of molds for molding optical elements used for press molding, which can maintain the surface roughness of the molding surface that comes into contact with the glass material during molding and can mold optical elements over a long period of time. It is being considered.

That is, such an optical element molding die is used as a mold base material formed from cemented carbide or cermet sintered with a metal material such as chromium or titanium as a binder, and as a glass material when manufacturing an optical element. A noble metal layer in direct contact and an intermediate layer formed between the mold base material and the noble metal layer are provided (see, for example, Patent Document 1).
The noble metal layer is made of a noble metal material such as platinum or iridium, and prevents the glass material from being fused. The intermediate layer is made of one or more materials selected from titanium nitride, chromium carbide, titanium carbide, niobium carbide, tantalum carbide, silicon carbide, alumina, zirconia, titanium, and chromium.
As described above, the formation of the intermediate layer containing a metal material such as titanium or chromium aims at preventing precipitation of the metal component contained in the mold base material on the molding surface. The formation of the intermediate layer is intended to prevent peeling of the noble metal layer by improving the adhesion between the mold base material and the noble metal layer, and to suppress an increase in the roughness of the molding surface due to thermal relaxation during press molding.
Japanese Patent Publication No.62-28093

However, in the conventional optical element molding die, the intermediate layer is formed of a compound containing a metal material such as titanium or chromium. For this reason, when press molding is repeated, there is a problem that the metal material is deposited on the surface of the noble metal layer, which is the molding surface, to cause fusion of the glass material. In addition, there is a problem that a small amount of oxygen penetrates from the noble metal layer into the intermediate layer, and this small amount of oxygen oxidizes the intermediate layer, resulting in a decrease in adhesion.
Furthermore, the metal material deposited on the molding surface is oxidized by heat during press molding, or uneven crystal growth occurs on the molding surface of the noble metal layer, so that the surface roughness of the molding surface gradually increases. was there. From the above, there are problems that repeated press molding causes problems such as reduction in surface accuracy of the optical element to be molded and inability to release due to biting of the glass material.

In addition, the cause of non-uniform crystal growth on the molding surface of the noble metal layer due to heat during press molding has been clarified by the inventors' diligent research.
That is, the present inventor has found that there is a relationship with an increase in molding surface roughness that occurs during molding of an optical element, depending on the crystal state of the intermediate layer or noble metal layer. Further, it has been found that noble metal materials such as platinum and iridium forming the surface layer are affected by the crystal orientation of each crystal grain of the intermediate layer and mold base material formed immediately below. Furthermore, when a metal material such as titanium or chromium was used for the intermediate layer, it was found that the crystal orientation of each crystal grain of the intermediate layer was affected by the crystal orientation of each crystal grain of the mold base material immediately below it. .

From the above-mentioned contents, when the intermediate layer is formed with crystal grains larger than the crystal grain size of the material constituting the mold base material, and the surface layer is further formed with a noble metal material, crystals for each crystal of the noble metal layer It has been found that the orientation is affected by the crystal orientation of each crystal grain of the intermediate layer itself and the crystal orientation of each crystal grain of the mold base material via the intermediate layer. Further, during press molding, it has been found that the crystal growth, oxidation rate, and progress of the mold base material due to heat differ for each crystal grain of the mold base material.
From the above two points, the present inventors have found that each crystal of the noble metal layer has different effects on the crystal of the noble metal layer depending on the crystal growth and oxidation rate and progress of the base material for each crystal grain of the base material. It has been found that the crystal growth, oxidation rate, and progress are different, resulting in non-uniform crystal growth and an increase in the roughness of the molding surface.

The present invention has been made in view of the above-described circumstances, and even if an optical element is repeatedly molded by press molding, an increase in surface roughness of the molding surface is prevented, and an optical element with high surface accuracy is molded. It is an object of the present invention to provide an optical element molding die that can be used and an optical element molding method using the same.

In order to solve the above problems, the present invention proposes the following means.
The invention according to claim 1 is an optical element molding die for press-molding a glass material to mold an optical element, the mold base material made of sintered cemented carbide or silicon carbide, and the mold base A surface layer formed on the surface of the material and in contact with the glass material during press molding, and an intermediate layer formed between the mold base material and the surface layer, wherein the surface layer is platinum, Formed of at least one element selected from palladium, iridium, osmium, ruthenium, rhenium, or an alloy or compound containing these elements, and the intermediate layer includes a base material surface layer, a metal layer, and a nitride layer, The base material surface layer is formed in an amorphous state from at least one material of tungsten, carbon, tungsten carbide, and silicon carbide so as to contact the surface of the mold base material, and the metal layer is Base material Between the surface layer and the surface layer, the nitride layer is formed of at least one metal material of chromium, titanium, aluminum, and molybdenum, and the nitride layer is formed between the metal layer and the surface layer. proposes aluminum, at least one element is formed of a nitride containing an optical element molding die according to claim Rukoto of molybdenum.

According to the optical element molding die according to the present invention, by forming the base material surface layer to the amorphous state, at the time of press forming, the surface layer the influence of the crystal orientation of the crystal grains each different type matrix Is not to be given to .
Therefore, according to the optical element molding die of the present invention, even if crystal growth or oxidation occurs in the mold base material by heating the optical element molding die, the crystal grains and crystal grain boundaries of the mold base material No influence is exerted on the surface layer, and an increase in the roughness of the molding surface in contact with the glass material can be prevented.

Further, according to the optical element molding die according to the present invention, a sufficient adhesion can be obtained by forming a metal layer made of chromium, titanium, aluminum, and molybdenum between the base material surface layer and the surface layer. It can be obtained, and stress generated by the thermal cycle during press molding can be relieved.
Therefore, even if press molding is repeated, peeling of the surface layer can be reliably prevented.

Still further, according to the mold for molding an optical element according to the present invention, a nitride layer formed of a nitride such as chromium nitride, titanium nitride, aluminum nitride, aluminum nitride titanium, molybdenum nitride has heat resistance and oxidation resistance. Therefore, even if repeated press molding is performed, oxygen can be prevented from entering the intermediate layer from the molding surface of the surface layer. For this reason, oxygen does not reach the metal layer formed of chromium, titanium, or the like, and it is possible to prevent a decrease in adhesion due to oxidation of the metal layer. Therefore, peeling of the surface layer can be prevented over a long period.
Further, since this nitride layer is also stable as a compound, a metal material such as titanium or chromium in the metal layer does not precipitate on the molding surface of the surface layer. Therefore, an increase in the roughness of the molding surface due to oxidation of the deposited metal material can be prevented, and the glass material can be prevented from being fused to the molding surface during press molding.

The invention according to claim 2 is the optical element molding die according to claim 1 , wherein the nitride layer includes a nitrogen concentration gradient layer in which the nitrogen concentration gradually decreases toward the metal layer. An optical element mold has been proposed.
According to the optical element molding die according to the present invention, the boundary between the nitride layer made of a nitrogen compound and the metal layer made of a metal material not containing nitrogen becomes unclear. Also, the nitride layer does not peel from the metal layer. Therefore, it is possible to reliably prevent an increase in the roughness of the molding surface of the surface layer without lifting the surface layer.

The invention according to claim 3 proposes an optical element molding method characterized by molding a glass material using the optical element molding die according to claim 1.

As described above, according to the first aspect of the present invention, the base material surface layer made of at least one of tungsten, carbon, tungsten carbide, and silicon carbide formed in an amorphous state is brought into contact with the mold base material. By forming the surface, it is possible to prevent the roughness of the molding surface of the surface layer in contact with the glass material from increasing, so that an optical element with high surface accuracy can be molded.
Further, by providing a metal layer made of at least one metal material of chromium, titanium, aluminum, and molybdenum between the layer and the surface layer, the glass material based on the peeling of the surface layer can be used when repeatedly pressing. It becomes possible to mold an optical element with high surface accuracy while reliably preventing fusion.
In addition, by forming a nitride layer made of titanium or chromium between the metal layer and the surface layer, the glass material is prevented from being fused to the molding surface during press molding, and the metal layer is Since it is possible to prevent a decrease in adhesion due to oxidation of the metal material to be formed, an optical element with high surface accuracy can be molded over a long period of time.

Further, according to the invention of claim 2 , since the boundary between the nitride layer and the metal layer is obscured, an increase in the roughness of the molding surface of the surface layer can be reliably prevented. The element can be molded for a longer period of time.

Furthermore, according to the invention of claim 3 , since the surface accuracy of the optical element is high, an optical element with high optical accuracy can be obtained.

1 and 2 show a first embodiment according to the present invention. The optical element molding die according to this embodiment is for manufacturing a convex lens (optical element) by press molding. As shown in FIG. 1, the optical element molding die 1 is formed on a pair of mold base materials 2 and 2 and a surface 2a of each mold base material 2, and contacts the glass material M during press molding. A surface layer 3 having a molding surface 3 a and an intermediate layer 4 formed between the mold base material 2 and the surface layer 3 are provided.
The mold base material 2 is formed of sintered cemented carbide or silicon carbide, and the surface 2a is formed in a concave shape in accordance with the radius of curvature of the convex lens.

As shown in FIG. 2, the intermediate layer 4 is made of a material such as tungsten or tungsten carbide formed in an amorphous state or a crystalline state composed of crystal grains of 1 to 2 μm in contact with the surface 2 a of the mold base 2. Formed in contact with the base material surface layer 5 and the surface 5a of the base material surface layer 5, formed in contact with the metal layer 6 made of a metal material such as chromium, titanium, and the surface 6a of the metal layer 6, And a nitride layer 7 made of a nitride containing an element such as chromium or titanium.
The surface layer 3 is made of a metal material such as platinum or iridium, and is formed in contact with the surface 7 a of the nitride 7. The surface layer 3 is formed by PVD (physical vapor deposition) or CVD (chemical vapor deposition) such as RF sputtering, ion beam sputtering, or vapor deposition.

  The base material surface layer 5 is formed by PVD such as RF sputtering, ion beam sputtering and vapor deposition, CVD, a method of ion-implanting a material for forming the base material surface layer 5, and an argon gas as a material for forming the base material surface layer 5. The film is formed by an ion-assisted film formation method in which film formation is performed while irradiating a mold base material by electrically accelerating ions such as ion beam mixing. Further, in order to efficiently suppress the crystal growth, while controlling the temperature of the material of the base material surface layer 5 and the temperature of the mold base material 2 to be lower than the crystal growth temperature of the material of the base material surface layer 5, the base material surface layer 5 is It is preferable to form. By these methods, the base material surface layer 5 can be formed while being controlled to be in an amorphous state or a crystalline state composed of 1 to 2 μm crystal grains.

  Nine types of optical element molding dies were produced by changing the materials and forming methods of the mold base material 2, the base material surface layer 5, the metal layer 6, the nitride layer 7 and the surface layer 3. A specific configuration is shown in Table 1.

The forming methods of Mold 1 to Mold 3 in Table 1 are as follows.
First, a mold base material 2 made of a cemented carbide mainly composed of tungsten carbide (WC) is formed by sintering, and a base material surface layer 5 made of tungsten carbide (WC) is formed on the surface 2a of the mold base material 2. It is formed by ion beam sputtering. Next, a metal layer 6 made of chromium (Cr) is formed by ion beam sputtering, and a nitride layer 7 made of chromium nitride (CrN) is formed by reactive sputtering in which chromium is sputtered while flowing nitrogen gas. Finally, a surface layer 3 made of platinum-iridium alloy (Pt-Ir), iridium-rhenium alloy (Ir-Re), or platinum (Pt) is formed by sputtering.

Moreover, the formation method of the shaping | molding die 4-the shaping | molding die 6 in Table 1 is as follows.
First, a mold base material 2 made of a cemented carbide mainly composed of tungsten carbide (WC) is formed by sintering, and a base material surface layer 5 made of tungsten carbide (WC) is formed on the surface 2a of the mold base material 2. It is formed by ion beam sputtering. Next, a metal layer 6 made of titanium (Ti) is formed by RF sputtering, and a nitride layer 7 made of titanium nitride (TiN) is formed by reactive sputtering in which titanium is sputtered while flowing nitrogen gas. Finally, a surface layer 3 made of platinum-iridium alloy (Pt-Ir), iridium-rhenium alloy (Ir-Re), or platinum (Pt) is formed by sputtering.

Moreover, the formation method of the shaping | molding die 7-the shaping | molding die 9 in Table 1 is as follows.
First, a mold base material 2 mainly composed of silicon carbide (SiC) is formed by sintering, and a base material surface layer 5 made of silicon carbide (SiC) is formed on the surface 2a of the mold base material 2 by CVD. . Thereafter, the surface 5a of the base material surface layer 5 is formed by mirror polishing. Next, a metal layer 6 made of chromium (Cr) is formed by RF sputtering, and a nitride layer 7 made of chromium nitride (CrN) is formed by reactive sputtering in which chromium is sputtered while flowing nitrogen gas. Finally, a surface layer 3 made of platinum-iridium alloy (Pt-Ir), iridium-rhenium alloy (Ir-Re), or platinum (Pt) is formed by RF sputtering.

As shown in Table 1, as the optical element molding die 1 of the three comparative examples for the molding die 1 to the molding die 9 described above, Comparative Example 1 in which the base material surface layer 5 is omitted, the base material surface layer 5 and nitriding Comparative Example 2 in which the material layer 7 was omitted and Comparative Example 3 in which the base material surface layer 5, the metal layer 6, and the nitride layer 7 were omitted from the mold 4 were produced. The manufacture of Comparative Examples 1 to 3 is performed in the same manner as the mold 1 and the mold 4.
In addition, although the composition of the nitride layer 7 in the mold 1 to the mold 3 and the mold 7 to the mold 9 is expressed as CrN in Table 1, actually Cr or Cr ₂ N is mixed with CrN. What you did is fine. Further, the composition of the mold 4 to 6 and the nitride layer 7 in the comparative example 1 is expressed as TiN in Table 1, but actually TiN and Ti or Ti ₂ N may be mixed. . Further, the composition of the mold 4 to the mold 6 and the nitride layer 7 in the comparative example 1 is not limited to TiN, and may be, for example, aluminum titanium nitride (TiAlN).

  About the above 12 types of optical element molding dies 1, the temperature of the optical element molding dies 1 is fixed at 580 ° C., and actually, the glass material M is repeatedly pressed to form the molding surface 3 a of the surface layer 3. An experiment was conducted with respect to the number of moldings until a defect occurred in a molded product that would become a convex lens. Table 2 shows the results of these experiments.

  According to the results in Table 2, with respect to the mold 1 to the mold 9 according to the embodiment of the present invention, there are defects in the molding surface 3a of the surface layer 3 and the molded product even when press molding is performed 3000 times or more. I was not able to admit. On the other hand, in Comparative Example 1, there was a problem that the surface of the molded product was clouded when press molding was repeated about 140 times.

Regarding Comparative Example 1, when the surface roughness of the molding surface 3a of the surface layer 3 at this time was measured, no increase in numerical roughness was confirmed. However, when the crystal grains forming the molding surface 3a were observed with an electron microscope, patterns similar to the crystal grains and crystal grain boundaries of the mold base material 2 were observed, and a small portion of the surface of each crystal grain was observed. There were irregularities and crystal grain boundaries were conspicuous. This is because the crystal orientation of each crystal grain exposed on the surface 2 a of the mold base 2 is different, and the crystal orientation of the metal layer 6 and the surface layer 3 formed thereon is affected by the crystal orientation of the mold base 2. This is because different films are formed on a crystal grain basis. That is, in the metal layer 6 and the surface layer 3, the degree of crystal growth and oxidation differs in the same units as the crystal grains of the mold base material 2 depending on the heat during molding, so that the roughness of the molding surface 3a increases. it is conceivable that.
Moreover, when the surface of the molded product was observed in detail, the same pattern as the molding surface 3a of the surface layer 3 was recognized. From the above, it is considered that the fine change in the surface shape of the molding surface 3a is transferred to the surface of the molded product, and fogging occurs.

On the other hand, when the molding surface 3a of the surface layer 3 is observed in detail for the molding die 1 to the molding die 9, the pattern is different from the crystal grains and grain boundaries of the mold base material 2, and the metal layer 6, nitride It can be seen that the layer 7 and the surface layer 3 are not affected by the crystal grains and grain boundaries of the mold base material 2. This is presumably because the crystal grain size of the base material surface layer 5 is 2 μm or less, which is smaller than the crystal grain size of the mold base material 2.
Therefore, in the case of the mold 1 to the mold 9, even if crystal growth or oxidation occurs in the mold base 2 by heating the optical element molding mold 1, crystal grains and crystal grains of the mold base 2 Since the influence of the field is not transmitted to the surface layer 3, an increase in the roughness of the molding surface 3a that contacts the glass material M can be prevented.

  Moreover, about the comparative example 2, when press molding is repeated about 70 times, the malfunction that the glass raw material M fuse | melts to the molding surface 3a of the surface layer 3 generate | occur | produces, and when a press molding is repeated further, a molded article cracks. It became impossible to continue press molding. When the molding surface 3a was observed in detail, discoloration was recognized in a part of the molding surface 3a. This discolored portion was found to be chromium or chromium oxide by elemental analysis, and it was found that chromium of the metal layer 6 was deposited on the molding surface 3a and a part thereof was oxidized. Therefore, it is considered that the glass material M was fused to these chromium and chromium oxide at the time of press molding.

On the other hand, even if the molding surface 3a of the surface layer 3 was observed in detail for the molding dies 1 to 9 and the comparative example 1, the above-described discolored portion was not observed. This is because nitrides such as chromium nitride, titanium nitride and aluminum titanium nitride have stable properties as compounds, and prevent the metal material forming the metal layer 6 from being deposited on the molding surface 3a of the surface layer 3. Because it is. Therefore, it is possible to prevent the glass material M from being fused to the molding surface 3a during press molding.
Further, since these nitrides have properties excellent in heat resistance and oxidation resistance, oxygen can penetrate from the molding surface 3a of the surface layer 3 to the metal layer 6 even if repeated press molding is performed. Stop. Therefore, even if it repeats press molding, the fall of the adhesive force by the oxidation of the metal material which forms the metal layer 6 can also be prevented.

  Further, in Comparative Example 3, when the press molding was repeated about 50 times, the glass material M was fused to the molding surface 3a of the surface layer 3, and a part of the molded product was clouded. When this molding surface 3a was observed in detail, it was confirmed that the adhesion was reduced and the surface layer 3 was peeled off from the mold base material 2. Further, it has been found that fusion of the glass material M and fogging of the molded product occur in the peeled portion of the surface layer 3. From this, it is considered that the glass material M is fused due to the exposure of the mold base material 2 and the molded product is fogged due to an increase in surface roughness due to the oxidation of the exposed mold base material 2.

  On the other hand, even when the molding surface 1a of the surface layer 3 was observed in detail for the molding die 1 to the molding die 9 and the comparative example 1, peeling of the surface layer 3 was not confirmed. This indicates that chromium and titanium forming the metal layer 6 have high adhesion, and it can be seen that the metal layer 6 prevents the surface layer 3 from peeling off.

  As described above, according to the optical element molding die 1, any one of tungsten, carbon, tungsten carbide, and silicon carbide formed in an amorphous or crystalline material having a grain size of 1 to 2 μm is used. By forming the base material surface layer 5 made of the material in contact with the mold base material 2, it is ensured that the roughness of the molding surface 3a of the surface layer 3 in contact with the glass material M is increased during press molding. Therefore, it is possible to mold a convex lens with high surface accuracy.

Further, by forming a metal layer 6 made of titanium or chromium between the base material surface layer 5 and the nitride layer 7 and the surface layer 3, the surface layer 3 can be peeled off during repeated press molding. It is possible to reliably prevent the fusion of the glass material M based on it and to mold a convex lens with high surface accuracy.
Further, by forming a nitride layer 7 made of titanium or chromium between the metal layer 6 and the surface layer 3, it is possible to prevent the glass material M from being fused to the molding surface 3a during press molding. In addition, since it is possible to prevent a decrease in adhesion due to oxidation of the metal material forming the metal layer 6, a convex lens with high surface accuracy can be molded over a long period of time.
Moreover, since the surface accuracy of the convex lens molded using this optical element molding die 1 is high, a convex lens with high optical accuracy can be obtained.

  Next, FIG. 3 shows a second embodiment according to the present invention. This embodiment has the same basic configuration as the optical element molding die 1 shown in FIGS. The structure of the layer 7 is different. Here, in FIG. 3, the nitride layer 7 will be described, and the same components as those in FIGS.

  That is, the nitride layer 7 includes a nitrogen concentration gradient layer 8 in which the nitrogen concentration gradually decreases toward the metal layer 6. Three types of optical element molding dies 1 having the nitrogen concentration gradient layer 8 were produced. A specific configuration is shown in Table 3.

The forming method of forming mold 10 to forming mold 12 in Table 3 is as follows.
First, a mold base material 2 made of a cemented carbide mainly composed of tungsten carbide (WC) is formed by sintering, and a base material surface layer 5 made of tungsten carbide (WC) is formed on the surface 2a of the mold base material 2. It is formed by ion beam sputtering. Next, a metal layer 6 made of chromium (Cr) is formed by ion beam sputtering, and then the nitrogen concentration is gradually increased by gradually increasing the amount of nitrogen gas introduced from 0 sccm to 8 sccm while performing this chromium film formation. The nitrogen concentration gradient layer 8 that increases in the following manner is formed. Then, the remaining nitride layer 7 made of chromium nitride (CrN) is formed by reactive sputtering in which chromium is sputtered while the introduction amount of nitrogen gas is maintained at 8 sccm. Finally, a surface layer 3 made of platinum-iridium alloy (Pt-Ir), iridium-rhenium alloy (Ir-Re), or platinum (Pt) is formed by ion beam sputtering.
Further, as a comparative example for these molds 10 to 12, Comparative Example 4 having the same configuration as the mold 1 described in the first embodiment was produced. In these molds 10 to 12 and Comparative Example 4, the materials of the mold base material 2, the base material surface layer 5, the metal layer 6, the nitride layer 7, and the surface layer 3 except for the presence or absence of the nitrogen concentration gradient layer 8. Are the same.

  With respect to these four types of optical element molding molds 1, the number of times of molding until a defect occurs in the molded surface 3 a of the surface layer 3 and the molded product that becomes the convex lens is actually repeatedly pressed using the glass material M. The experiment was conducted. The temperature of the optical element molding die 1 at the time of molding was 580 ° C. in the press molding up to 3000 times, and 600 ° C. in the subsequent press molding. Table 4 shows the results of these experiments.

According to the result of Table 4, even if it performed 3000 times of press molding at 580 degreeC, the malfunction did not generate | occur | produce in the shaping | molding die 10-the shaping | molding die 12 and the comparative example 4. FIG. However, as a result of further press molding after changing the temperature to 600 ° C., in the mold 10 to the mold 12, no trouble occurred even after 2000 times of press molding, whereas in the comparative example 4, The glass material M was found to be fused after about 1500 times of press molding.
When the molding surface 3a of the surface layer 3 of the comparative example 4 was observed in detail, a part of the surface layer 3 and the nitride layer 7 was peeled off from the metal layer 6, and the chromium of the metal layer 6 was exposed at the peeled portion. Was. It is considered that the glass material M is fused to the chromium of the metal layer 6.

As described above, according to this optical element molding die 1, the nitrogen concentration gradient layer 8 is formed to eliminate a clear boundary between the metal layer 6 and the nitride layer 7, thereby reducing the press molding temperature. Even if it is raised, the nitride layer 7 does not peel off from the metal layer 6, so that it is possible to reliably prevent an increase in the roughness of the molding surface 3 a of the surface layer 3. Therefore, a convex lens with high surface accuracy can be molded over a longer period.
Moreover, since the surface accuracy of the convex lens molded using this optical element molding die 1 is high, a convex lens with high optical accuracy can be obtained.

  In the above embodiment, the crystal grain size of the base material surface layer 5 is set to 1 to 2 μm. However, the crystal grain size of the base metal surface layer 5 is not limited to this and may be at least smaller than the crystal grain size of the mold base material 2. However, the crystal grain size of the base material surface layer 5 is preferably small and is particularly preferably 1 μm or less.

  In addition, although the base material surface layer 5 is formed on the surface 2a of the mold base material 2, the present invention is not limited to this. At least the base on which the metal layer 6 is formed is in an amorphous state or crystal grains of the mold base material 2 What is necessary is just to be formed in the crystalline state which consists of a crystal grain of a diameter smaller than a diameter. Therefore, for example, after forming the mold base material 2, ions such as argon are implanted from the surface 2 a of the mold base material 2, and the vicinity of the surface 2 a of the mold base material 2 is in an amorphous state or a particle size of 1 to 2 μm. The metal layer 6 may be formed on the surface 2 a of the mold base material 2 in a crystalline state composed of crystal grains.

  Further, the combination of the material forming the mold base material 2 and each layer of the optical element molding mold 1 is not limited to the mold 1 to the mold 12. That is, the mold base material 2 may be selected from a cemented carbide such as tungsten carbide or a material mainly composed of silicon carbide, and the base material surface layer 5 may be one of tungsten, carbon, tungsten carbide, and silicon carbide. What is necessary is just to select from the above materials. That is, for example, the composition of the base material surface layer 5 in the molds 1 to 6 may be changed from tungsten carbide (WC) to tungsten (W). Further, for example, the composition of the base material surface layer 5 in the mold 7 to the mold 9 may be changed from silicon carbide (SiC) to carbon (C). In the case of the above composition, the base material surface layer 5 may be formed by ion implantation in addition to PVD and CVD.

The metal layer 6 may be selected from at least one metal material of chromium, titanium, aluminum, and molybdenum, and the nitride layer 7 is a nitride containing at least one element of chromium, titanium, aluminum, and molybdenum. You can choose from. However, the metal material of the metal layer 6 and the metal material contained in the nitride of the nitride layer 7 are preferably the same.
Furthermore, the surface layer 3 may be selected from at least one metal material of platinum, palladium, iridium, osmium, ruthenium, rhenium, or an alloy or compound containing these elements. That is, the surface layer 3 is made of, for example, an alloy such as platinum-palladium alloy (Pt—Pd), platinum-rhenium alloy (Pt—Re), iridium-ruthenium alloy (Ir—Ru), iridium (Ir), osmium ( Os), ruthenium (Ru), and rhenium (Re) may be used.

Further, the intermediate layer 4 of the optical element molding die 1 is composed of the base material surface layer 5, the metal layer 6 and the nitride layer 7. However, the present invention is not limited to this. It may be configured only by the layer 6. Even in this configuration, there is an effect that the glass material M can be reliably prevented from being fused based on the peeling of the surface layer 3 during press molding.
Further, the intermediate layer 4 may be configured to further exclude the metal layer 6 from the above configuration, that is, may be configured only from the base material surface layer 5. Even in this configuration, there is an effect that it is possible to reliably prevent an increase in the roughness of the molding surface 3a of the surface layer 3 that contacts the glass material M during press molding.

Further, the optical element molding die 1 is for molding a convex lens, but is not limited to this, as long as it molds an optical element such as a flat lens, a concave lens, a prism, or a cell having an optical surface. Good.
As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the concrete structure is not restricted to this embodiment, The design change etc. of the range which does not deviate from the summary of this invention are included.

It is the schematic which shows the structure of the type | mold for optical element shaping | molding based on 1st, 2nd embodiment of this invention. FIG. 2 is an enlarged cross-sectional view showing the main part of FIG. 1 in the optical element molding die according to the first embodiment of the present invention. FIG. 4 is an enlarged cross-sectional view showing a main part of FIG. 1 in an optical element molding die according to a second embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical element shaping | molding die 2 Type | mold base material 2a Surface 3 Surface layer 4 Intermediate | middle layer 5 Base material surface layer 6 Metal layer 7 Nitride layer 8 Nitrogen concentration gradient layer M Glass material

Claims (3)

An optical element molding die for molding an optical element by press molding a glass material,
A mold base material made of sintered cemented carbide or silicon carbide, a surface layer formed on the surface of the mold base material and in contact with the glass material during press molding, and the mold base material and the surface layer An intermediate layer formed between,
The surface layer is formed of at least one element selected from platinum, palladium, iridium, osmium, ruthenium, rhenium, or an alloy or compound containing these elements,
The intermediate layer includes a base material surface layer, a metal layer, and a nitride layer,
The base material surface layer is formed in an amorphous state from at least one material of tungsten, carbon, tungsten carbide, and silicon carbide so as to contact the surface of the mold base material ,
The metal layer is formed of at least one metal material of chromium, titanium, aluminum, and molybdenum between the base material surface layer and the surface layer,
The nitride layer is chromium, titanium, aluminum, at least one element is formed of a nitride containing an optical element molding die according to claim Rukoto of molybdenum between the metal layer and the surface layer.   The optical element molding die according to claim 1, wherein the nitride layer includes a nitrogen concentration gradient layer in which a nitrogen concentration gradually decreases toward the metal layer. A glass material is molded using the optical element molding die according to claim 1 .

Images