JPS63319218A - Production of optical device - Google Patents

Abstract

PURPOSE:To produce an optical device in which a fault such as strain and deformation is not caused in a short time by regulating only the vicinity of the surface of a press-molding face of a stock for molding to temp. not lower than the transition point of glass and press-molding the stock with a mold regulated to temp. not lower than this temp. CONSTITUTION:A stock 1 which has a protruding face 1b correspondent to the fitting face 2a of a lower mold 2 and is used for molding an optical device is arranged on the fitting face 2a of the lower mold 2 arranged in a drum mold 5. The top face of the stock 1 is previously formed into a recessing face 1a close to the shape of a required molded article. The recessing face 1a is heated with an infrared heater or the like and only the vicinity of its surface is regulated to temp. not lower than the transition point of glass. The upper mold 3 of the metallic mold for pressing is heated together therewith and its temp. is regulated to temp. not lower than the temp. of the surface of the stock 1. Then this upper mold 3 is pressed on the recessing face 1a and the press- action face 3a of the upper mold 3 is transferred thereon. Thereafter all parts of the mold are cooled and the molded article of the optical device finished in press-molding is taken out therefrom.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an optical element manufacturing method for manufacturing an optical element by pressure molding. More specifically, the present invention relates to a method of manufacturing an optical element with high surface accuracy that requires only pressure molding and eliminates the need for grinding.

(Prior Art) Conventionally, many optical elements such as lens 8 prisms and filters have been molded by polishing a material for molding optical elements such as glass. However, this polishing process requires a considerable amount of time and skill, making it difficult to manufacture a large number of optical elements in a short period of time.

Therefore, in recent years, a method has been developed in which optical element molding materials are housed in a pair of molding chambers and pressurized to mold optical elements such as lenses.

Here, a conventional example of molding an x-dimensional element using this method will be described with reference to FIG. 5 and wcG diagram.

The mold for molding an optical element shown in the figure is for molding a concave lens, and consists of an upper mold 16, a lower mold 17, and a working mold 18. The upper mold 16 has a convex inner surface 16 with a mirror finish to form one functional surface of the optical element to be molded. The lower mold 17 has a similarly mirror-finished concave inner surface 17m so as to mold the functional surface on the opposite side of the optical element. Further, the molder 8 molds the side surface of the optical element.

To mold an optical element with this mold, first
A molding material 13 is placed on the inner surface 17a of the molding material 13, and an upper mold 16 is further provided thereon. Next, it is heated in this state and set in a pressurizing device (not shown). And molding material 1
After heating the entire 3 to the temperature required for molding, pressurize the upper mold 16 with a pressure rod 15 to mold the optical element 14.
to form. Next, after applying pressure for a sufficient period of time to mold the molding material 13 into the optical element 14, the entire mold is cooled, and then the optical element 14 indoors is removed.

According to such a pressure molding method, an optical element with high surface precision can be obtained without performing grinding after molding.

(Problems to be Solved by the Invention) However, in this pressure molding method, when pressurizing the molding material with a mold, the entire material is heated to a temperature above the glass transition point to soften it. There were problems like. That is, it takes 15 to 20 minutes to heat the molding material as described above. Further, the time required for pressurization is several minutes to about 10 minutes since the entire material is deformed. Furthermore, if the entire material is cooled quickly after being pressurized, distortion tends to occur inside the molded product, causing birefringence, and making it more likely to break with a small amount of force. In order to prevent the occurrence of such distortion, it is necessary to slowly cool the material to a predetermined temperature at a rate of 3° C. to several 10° C. per minute, and a considerable amount of time is required from heating to cooling.

The present invention was made to solve the above-mentioned problems, and provides an optical element that shortens the time required from heating to cooling and does not cause defects such as distortion and deformation in the obtained molded product. The purpose is to provide a manufacturing method.

(Means for Solving the Problems) Therefore, in order to solve the above-mentioned conventional problems, the optical element manufacturing method of the present invention includes disposing an optical element molding material between the upper mold and the lower mold. In the method for manufacturing an optical element in which the material is pressure-molded, when the molding material is pressure-molded,
Only the vicinity of the surface of the surface to be pressurized of this molding material is heated to a temperature higher than the glass transition point, and the temperature of the mold to be pressed against this surface is set to be higher than the surface temperature of the heated molding material. It is characterized by pressure molding.

(Function) The function of the present invention configured as described above will be explained.

In the optical element manufacturing method according to the present invention, the surface of the molding material is heated. The surface of this material may be a functional surface on only one side of the desired optical element, or may be a functional surface on both sides including a functional surface on the opposite side. In any case, only the desired molded surface is heated to a temperature above the glass transition point and softened. As a heating means for this purpose, an infrared heater is more suitable than a heater using a nichrome wire which heats the entire molding material.

The temperature of the mold for pressure-molding the molding material whose surface has been heated and softened in this manner is set to be higher than the temperature of the surface of the heated material, thereby shortening the molding time. .

In the molding method of the present invention, the workpiece to be heated, pressurized, and cooled is limited to the surface of the molding material, so the time required for this process is significantly shortened. Furthermore, when this material is rapidly cooled, only the surface of the material is hardened, so there is very little risk of distortion or deformation occurring in the molded product.

As the molding material supplied in such a molding method, one having a shape roughly similar to the desired molded product is suitable. That is, the present invention is particularly suitable for, for example, pressure molding of a molding material that has been processed into a spherical surface, which is relatively easy to grind, into an aspherical surface that is difficult to grind.

(Example) Examples of the present invention will be described below with reference to the drawings.

Figure Wc1 is a diagram for explaining the first embodiment of the present invention, and shows a schematic cross-sectional view of a press mold suitable for pressure molding only one functional surface.

In the figure, this press mold is made up of a shed 3, a lower mold 2, and a set of molds 5, and a molding material 1 is placed on the lower mold 2.

The molding material 1 has a shape approximating a concave meniscus lens having an aspherical surface on one functional surface as a desired molded product, that is, both functional surfaces are machined into spherical surfaces, which can be easily manufactured by conventional grinding methods. A material for molding concave meniscus lenses.

The lower mold 2 has, on its upper side, a concave surface corresponding to the convex surface 16 of the molding material as a retaining surface 2a. This holding surface 2
Depending on a, the molding material 1 is not molded, and the receiver serves to catch the material when it is pressurized.

The upper plate 3 has a convex surface having a desired aspherical surface on its lower side as a pressing surface 3m. This press action surface 3a
is a surface for forming the concave surface 1a of the molding material 1 into an aspherical functional surface, and has a predetermined surface accuracy.

In order to apply the method of the present invention to the apparatus configured as described above, first, the molding material 1 as described above is placed on the lower mold 2 with its convex surface 16 facing downward. In this state, the retaining surface 2a of the lower mold 2 and the convex surface 16 of the molding material 1 are in even contact with each other.

Next, the molding material 1 is heated from near the concave surface 1a of the molding material 1. As this heating means, it is preferable to use, for example, a heater (not shown) using infrared rays, which rapidly heats and softens only the vicinity of the surface of the molding material 1. This heater heats the molding material 1 until the heating depth at the concave surface 1 is about 2.5 times the desired deviation depth and the conductivity is higher than the glass transition point.

Then, the shed 3 is heated together with heating.

The heating temperature of the upper mold 3 is higher than the heating temperature of the concave surface 1a of the molding material 1, and the upper mold 3 is heated over 1 m of the concave surface 1a of the molding material 1.
This is useful for shortening the time required for pressure molding when pressed.

Thereafter, while maintaining the heating temperature of the upper mold 3, the upper mold 3 is pressed by a pressure rod (not shown) to form the concave surface 1 of the molding material 1.
1 is pressurized. After applying pressure for a time sufficient to transfer the pressure on the press working surface 3 of the shed 3, the entire mold is cooled, and the molded product that has been press-formed is taken out.

As mentioned above, if only the vicinity of the surface of the concave surface 1a of the molding material 1 is heated and softened in a short time, but if this surface is subjected to carbon vapor deposition, the surface becomes black and absorbs heat well. That's it. However, heating the carbon-deposited molding material 1 in air will burn the carbon, so in such cases it is necessary to carry out the work in an inert atmosphere such as nitrogen gas or in a vacuum.

The deposited carbon is burned off by introducing air during cooling, so it does not cause any problems to the molded product.

A unique advantage of this embodiment is that only one side of the molding material can be molded.

Next, a second embodiment of the present invention will be described with reference to FIG. This figure is a cross-sectional view of the press die used in this example, and shows that the upper die 8, the lower die 7, and the molding material 6 are located between the upper die 8 and the lower die 7 and are in contact with them. It is made up of a Yatoi 9 that is held in place. This press mold differs from the first embodiment in that both functional surfaces of the molding material 6 can be molded. Therefore, the upper die 8 and the lower die 7 are provided with pressing surfaces 8m and 7m, respectively.

In this embodiment, the concave surface 6a of the molding material 6
Not only is the concave surface 6b of the material 6 heated and softened, but also the concave surface 6b of the material 6 is heated and softened, and then pressure molded by the upper mold 8 and the lower mold 7, respectively. As in the first embodiment, the material to be supplied as the molding material 6 has a shape roughly similar to the desired molded product, and the functional surface of the material can be easily molded by ordinary grinding. It is a spherical surface. In addition, by press-forming the press working surfaces 8 a e 7 m of the upper die 8 and lower die 7 as aspherical surfaces corresponding to each functional surface of the desired molded product in the same manner as in the first embodiment, both sides function. A concave meniscus lens having an aspherical surface on each surface is obtained.

Furthermore, according to the present invention, as can be understood from FIGS. 3(-) and 3(b) showing the third embodiment, it is possible to obtain a lens shaped lens for use in a lens array or the like.

In FIG. 3(,), 11 is a mold 11 having a pressing surface 11a, and this mold 11 is used in the same manner as in the first embodiment.
By press-molding the end surface of the rod-shaped material 10, an optical element 12 shown in FIG. 3(b) is obtained.

This method is also suitable for processing the tips of single fibers.

In this third embodiment, the molding material is rod-shaped, and the only part of the material that needs to be molded is the end surface. Therefore, the method of the present invention, in which only the surface to be processed is heated and softened and press-formed using a disk, is also suitable for this embodiment.

In the present invention, the shape of the surface to be pressure molded is not limited, and it is possible to mold an aspherical surface onto any uneven spherical surface. Various spherical surfaces.

Various elemental elements can be obtained by forming an aspherical surface.

Next, effects common to each of the above embodiments will be explained based on actual results.

Conventionally, it took about 15 to 20 minutes to heat the entire molding material, but when heating only the surface to be molded as in the present invention, it only takes about 30 seconds. Moreover, since the time required for pressurization is not to deform the entire molding material, but to deform the surface of the material, the time required for pressurization, which used to take several minutes to 10 minutes, is now reduced to a few seconds. Furthermore, in order to suppress the distortion that occurs during cooling after pressurization, conventional methods require
Whereas slow cooling was performed at several tens of degrees Celsius to a predetermined temperature,
In the present invention, rapid cooling is possible because there is no need to consider the occurrence of distortion. As a result, the time required for cooling has been shortened to approximately IA~115 compared to the conventional method.

Based on these results, FIG. 4(1) shows the press molding cycles for the conventional method and the method of the present invention. The molding material used for this press molding is
Among optical glasses, heavy flint 5F14 is used, and its molding conditions are Tg (glass transition point): 485°C, At (
Molding temperature): 526°C, sp (softening point): 586°C.

As can be understood from the figure, in the conventional method, one cycle from heating to cooling takes 50 minutes, whereas in the method of the present invention, one cycle takes 15 minutes, which is a significant reduction in time.

In addition, to explain the experimental results in more detail, the radius of curvature of the left functional surface is 42 mm as shown in the cross section in Fig. 4(b).
．． 67. A spherical lens with a radius of curvature of 36.27 on the right functional surface (the glass material is the above-mentioned 5F14) was used as a molding material, and the left side surface was installed in the underflow, and the right side surface was molded with a lens according to the present invention (first embodiment). When molding was carried out under a load pressure of 100 Hg/m2 and a pressurization time of 10 seconds, an aspherical lens with a reference R of 36,22 and a deviation of 50 μm could be obtained.

(Effects of the Invention) As explained above, according to the optical element manufacturing method of the present invention, it is possible to obtain a press molding method in which the time required for each of heating, pressurization, and cooling is significantly shortened. A molded product without distortion or deformation can be obtained.

The present invention is particularly suitable for mass production of aspheric lenses, which conventionally required highly skilled techniques.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a press mold used in a first embodiment of the present invention, FIG. 2 is a cross-sectional view of a press mold used in a second embodiment of the present invention, and FIG. 3 is a cross-sectional view of a press mold used in a second embodiment of the present invention. Figure 4 (a) is a diagram comparing the time required for one cycle of the conventional method and the method of the present invention. Figure 4 (C) is a diagram for explaining the experimental results. The sectional view of the material, FIGS. 5 and 6, are sectional views of a conventional pressure molding apparatus.

Claims (2)

[Claims] (1) In an optical element manufacturing method in which a material for molding an optical element is placed between an upper mold and a lower mold and pressure molded, in pressure molding the molding material, applying pressure to the molding material. Pressure molding is performed by heating only the vicinity of the surface of the surface to be molded to a temperature higher than the glass transition point, and setting the temperature of the mold to be pressed against this surface to higher than the surface temperature of the heated molding material. Characteristic optical element manufacturing method. (2) The optical element according to claim 1, wherein the optical element molding material placed between the upper mold and the lower mold has a shape that approximates the shape of a desired molded product. Production method.