JPH0517524B2 - - Google Patents

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to an improvement in a method for manufacturing a reflecting mirror.

(Prior Art) Conventionally, in order to manufacture a reflecting mirror having an optical mirror surface, a method of directly cutting, grinding, polishing, and mirror coating a workpiece has been carried out.

By the way, most reflecting mirrors have a concave shape, so
Hole drilling is required in the cutting process. For this reason, when manufacturing a small-sized reflecting mirror using the method described above, it is restricted by the size of the cutting tool, making drilling difficult. Specifically, when drilling a hole, if the inner diameter is about several tens of millimeters and the length is about twice that length, the bite shank becomes thin and has low rigidity, which results in crack vibrations occurring during drilling, which can cause processing to fail. It becomes difficult. Further, similar restrictions apply to the grinding and polishing processes, which restricts the shape and dimensions of the reflecting mirror, making it difficult to achieve a smaller size and higher precision. That is, when improving the surface roughness by polishing, it is difficult to process the inner surface of the hole, and there are restrictions on the shape of the inner surface of the hole and the measurement of the surface roughness. Furthermore, when manufacturing a plurality of reflecting mirrors having the same shape, it is necessary to repeat the above-described complicated process one by one, which causes problems such as variations in product precision and an increase in production costs.

(Problems to be Solved by the Invention) The present invention has been made to solve the above-mentioned conventional problems. The purpose of this invention is to provide a method for mass-producing mirrors with high precision and at low cost.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a method for producing a reflecting mirror having a penetrating hole and having an inner surface of the hole as a mirror surface, which has the same shape as the hole of the reflecting mirror. A first step of processing the base material,
a second step of forming a metal thin film on the outer peripheral surface of the base material; a third step of coaxially inserting the base material into a backing ring having a hole larger in diameter than the base material; a fourth step of filling the gap between the backing pin and the backing pin with an electroformed layer; and applying a sudden temperature change to the base material to which the backing pin is integrally adhered via the electroformed layer to form the metal thin film. a fifth step of separating the electroformed layer with a mirror surface transferred thereto and the backing cap from the base material on which the metal thin film is formed, the electroformed layer having a thermal expansion coefficient lower than that of the base material. The electroformed layer is made of a material having a large diameter, and the separation in the fifth step is performed using a difference in coefficient of thermal expansion between the electroformed layer and the base material.

As the base material, for example, an amber alloy or the like can be used.

The metal thin film coated on the outer circumferential surface of the base material acts as a peeling material when the electroformed layer is peeled off by applying a sudden temperature change. As such a metal thin film,
For example, gold (Au), copper (Cu), nickel (Ni), aluminum (Al), silver (Ag), platinum (Pt), etc. can be used. However, it is necessary to select a combination of the materials of these metal thin films and the material of the electroformed layer so that they are not of the same quality. Further, the thickness of the metal thin film may be approximately 10 Å to 1000 Å.

The electroformed layer becomes a reflective surface of a reflective mirror after being separated from the metal thin film. As such an electroformed layer, for example, Ni, Cr, Ni-Cr alloy, etc. can be used. In addition, the thickness of the electroformed layer is 5 μm to 30 μm.
It is desirable to set it to about mm. Note that, prior to forming the electroformed layer on the metal thin film, an electroless plating film such as an electroless nickel plating film may be formed on the metal thin film for the purpose of improving the reflection characteristics of the reflective surface. .

The backing ring is formed by cutting, polishing, etc. the workpiece, and its material is, for example, Ni,
Amber alloy can be used.

Examples of means for causing the above-mentioned rapid temperature change include immersing the base material on which the backing ring is formed in a cooling medium such as liquid nitrogen to rapidly cool it, and rapidly heating the base material by spraying high-temperature heating gas onto the base material. method may be adopted.

(Function) According to the present invention, a base material having the same shape as the hole of the reflecting mirror is processed, a thin metal film is formed on the outer peripheral surface of the base material, and a backing material having a hole with a larger diameter than the base material is formed. After coaxially inserting the base material into and filling the gap between the metal thin film and the backing cap with an electroformed layer,
The backing pawl applies a rapid temperature change to the base material integrally attached via the electroformed layer. At this time, since the electroformed layer is made of a material with a larger coefficient of thermal expansion than the base material, a mirror surface is transferred by the thin metal film by utilizing the difference in coefficient of thermal expansion between the electroformed layer and the base material. The electroformed layer and the backing cap can be separated from the base material on which the metal thin film is formed. Moreover, by applying the rapid temperature change, the temperature of the metal thin film coated on the surface of the base material changes more rapidly than other members. Therefore, the separation operation can be performed reliably by the synergistic effect of the use of the difference in thermal expansion coefficient between the electroformed layer and the base material and the rapid temperature change of the metal thin film. As a result, a reflecting mirror consisting of an electroformed layer serving as a reflecting surface and a backing layer can be manufactured.

Moreover, once the metal thin film-coated base material is produced, any number of reflecting mirrors having the same shape and less variation in precision can be manufactured using the base material.

Furthermore, the backing pin is produced by machining from a workpiece, and requires drilling to form a substantially truncated conical hole therethrough. However, since the inner surface of the backing cap does not function as a reflective surface after manufacturing the reflecting mirror, the drilling process does not require as much precision as the conventional method of manufacturing the reflecting mirror from the workpiece itself. Polishing of the inner surface is also unnecessary. Therefore, a reflecting mirror having a desired shape and dimensions can be mass-produced with high precision and at low cost without being subject to constraints on shape and dimensions resulting from processing steps.

(Embodiments of the Invention) Hereinafter, embodiments of the present invention will be described with reference to the drawings.

First, a workpiece made of amber alloy is cut,
A base material 1 having a substantially truncated conical shape that was reflected by a reflecting mirror to be manufactured was prepared by performing machining such as grinding and polishing. Subsequently, a gold (Au) thin film 2 having a thickness of 10 Å was formed on the outer peripheral surface of the base material 1 by gold plating (as shown in FIG. 1). Subsequently, a backing capacitor 3 having a substantially truncated conical hole passing through the workpiece made of an amber alloy is produced by drilling and grinding, and the hole in the backing capacitor 3 is made of the gold thin film of the base material 1. After placing it on the outer circumferential surface of 2 with an interval of about 3 mm,
Nickel electroforming was performed to form a 3 mm thick Ni electroformed layer 4 between the gold thin film 2 of the base material and the inner surface of the backing cap 3 (as shown in Figure 2).

Next, when the base material 1 with the backing cap 3 integrated through the Ni electroformed layer 4 was immersed in liquid nitrogen and rapidly cooled, due to the difference in thermal expansion coefficient between the base material 1 and the Ni electroformed layer 4. The Ni electroformed layer 4 and the backing cap 3 are separated from the base material 1 with the gold thin film 2 as a boundary, and as shown in FIG. A reflecting mirror 5 consisting of a cast layer 4 could be manufactured.

In addition, when the same process as described above was carried out multiple times using the coated base material 1 of the gold thin film 2 from which the Ni electroformed layer 4 and the backing cap 3 were separated, it was found that even the already manufactured reflector was included. By using this method, we were able to manufacture multiple reflecting mirrors with the same shape and little variation in accuracy.

In the above embodiment, the base material was made of an amber alloy, the electroformed layer was made of nickel, and the backing cap was made of an amber alloy, and the reflector was manufactured by rapid cooling, but the present invention is not limited thereto. For example, a reflecting mirror can be manufactured in the same manner as in the embodiment by forming the base material from an amber alloy, the electroformed layer from nickel, and the backing ring from a nickel alloy, and rapidly heating them.

In the above example, an Au thin film was used as the metal thin film covering the outer peripheral surface of the base material, but the same reflective mirror as in the example can be obtained by using a thin film of Cu, Ni, Al, Ag, or Pt instead of the Au thin film. can be manufactured. However, when using a Ni thin film, an electroformed layer made of Cr was used.

[Effects of the Invention] As detailed above, according to the present invention, a reflecting mirror with a desired shape and dimensions can be mass-produced with high precision, at low cost, without being subject to constraints on shape and dimensions resulting from the processing process. Furthermore, it has remarkable effects such as being able to be effectively used in optical elements and the like.

[Brief explanation of the drawing]

1 to 3 are cross-sectional views showing the manufacturing process of a reflecting mirror in an embodiment of the present invention. 1...Base material, 2...Gold thin film, 3...Backing material, 4...
Ni electroformed layer, 5...Reflector.

Claims (1)

[Scope of Claims] 1. In manufacturing a reflecting mirror having a penetrating hole and having a mirrored inner surface of the hole, a first step of processing a base material having the same shape as the hole of the reflecting mirror; a second step of forming a metal thin film on the outer circumferential surface of the material; a third step of coaxially inserting the base material into a backing cap having a hole larger in diameter than the base material; and a fourth step of filling the gap between the backing cap and the base material with an electroformed layer, and applying a sudden temperature change to the base material, on which the backing ring is integrally adhered via the electroformed layer, to create a mirror surface by the metal thin film. a fifth step of separating the transferred electroformed layer and the backing cap from the base material on which the metal thin film is formed, the electroformed layer having a larger coefficient of thermal expansion than the base material. A method for manufacturing a reflecting mirror, wherein the separation in the fifth step is performed using a difference in coefficient of thermal expansion between the electroformed layer and the base material. 2. The method for manufacturing a reflecting mirror according to claim 1, wherein the metal thin film has a thickness of 10 Å to 1000 Å. 3. The method for manufacturing a reflecting mirror according to claim 1, wherein the electroformed layer is made of nickel, and the base material is made of an amber alloy. 4. A patent characterized in that the rapid temperature change in the fifth step is performed by immersing the base material, on which the backing pin is integrally adhered via the electroformed layer, in liquid nitrogen. A method for manufacturing a reflecting mirror according to claim 1.