JPH10133093A - Reflector holder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a reflector holder capable of reducing a shape change in a reflecting face even when an environmental change is generated and suitable for a highly accurate reflecting optical system by using the same material for a reflector and a base and setting up the center thickness of the reflector to the same thickness as the base. SOLUTION: The reflecting face 1a of the reflector 1 consists of a concave face, a convex face or an aspherical face. The base 2 holds the reflector 1. The reflector 1 is fixed to the base 2 by adhesion or fusion by the use of an adhesive member 3. A base supporting member 4 supports the base 2 and is fixed on a part of a casing. The reflector 1 and the base 2 are constituted of the same material. The linear expansion coefficient of the adhesive member 3 is different from that of the reflector 1 and the base 2. The center thickness of the reflector 1 is almost the same (a difference <=10%) as the thickness of the base 2. Consequently the reflector holder capable of reducing a shape change in the reflecting face even when an environmental change is generated and suitable for a highly accurate reflecting optical system is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflecting mirror holding device, and more particularly to a reflecting optical system in which a reflecting mirror is adhered or fused to a substrate with an adhesive member and fixed in a housing (lens barrel). It is suitable for use in optical systems such as astronomical telescopes and catadioptric systems (hereinafter referred to as "reflective optical systems").

[0002]

2. Description of the Related Art Conventionally, a reflecting optical system is constructed by housing a plurality of reflecting mirror devices in which a reflecting mirror having a concave surface, a convex surface, a parabolic surface, or the like is mechanically fixed to a substrate or fixed with an adhesive. I have. In general, a reflecting optical system using a plurality of reflecting mirror devices has a feature that a large diameter and a long focal length can be obtained relatively easily. Each of the reflecting mirror devices constituting these reflecting optical systems is held in a holding section and housed in a lens barrel.

[0003]

Generally, the reflecting optical system is difficult to assemble because of its long focal length, large diameter, and large in many cases, and the assembling precision is very severe. For this reason, each element constituting the reflective optical system is not affected by environmental changes such as ambient temperature and humidity, has little change over time, and is sufficiently large to withstand vibrations and shocks during transportation and the like. A mechanism is required.

For example, when the environmental temperature changes, the shape of the reflecting surface changes due to differences in the coefficient of linear expansion of the reflecting mirror, the coefficient of linear expansion of the substrate, and the longitudinal elastic coefficient of the adhesive for bonding the reflecting mirror to the substrate. The problem arises that the temperature decreases.

According to the present invention, the material and center thickness of the reflecting mirror, the material of the substrate for fixing and holding the reflecting mirror, and the material of the adhesive member for bonding or fusing the reflecting mirror to the substrate are appropriately set. It is an object of the present invention to provide a reflecting mirror holding device suitable for a high-precision reflecting optical system in which the shape of a reflecting surface does not change much even if there is an environmental change.

[0006]

According to the present invention, there is provided a reflecting mirror holding apparatus comprising: (1-1) when a reflecting mirror is fixedly held on a substrate by bonding or fusing with an adhesive member, the materials of the reflecting mirror and the substrate are changed; It is characterized in that the center thickness of the reflector and the thickness of the substrate are substantially the same.

(1-2) An adhesive having a longitudinal elastic modulus of 1/1000 or less of the longitudinal elastic modulus of the reflecting mirror when the reflecting mirror is fixed and held on the substrate by bonding or fusing the reflecting mirror with an adhesive member. It is characterized by using.

(1-3) When the reflecting mirror is fixed or held on the substrate by bonding or fusing with an adhesive member, the difference between the linear expansion coefficient of the reflecting mirror and the linear expansion coefficient of the substrate is 1 × 10 ^−7. It is characterized by the following.

(1-4) When the reflecting mirror is fixed or held to the substrate by bonding or fusing with an adhesive member, an adhesive having a longitudinal elastic coefficient of 1/1000 or less of the longitudinal elastic coefficient of the reflecting mirror is used as the adhesive member. And the difference between the coefficient of linear expansion of the reflector and the coefficient of linear expansion of the substrate is 1 × 10 ⁻⁷ or less.

(1-5) When the reflecting mirror is fixed or held to the substrate by bonding or fusing with an adhesive member, the longitudinal elastic coefficients of the reflecting mirror and the substrate are E ₁ and E ₂ , respectively, and the center of the reflecting mirror is When the thickness is t ₁ and the thickness of the substrate is t ₂ , (E ₂ / E ₁ ) ^1/3 × t ₂
It satisfies the condition of ≦ t ₁ .

[0011]

FIG. 1 is a perspective view of a main part of a first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a reflecting mirror, and 1a denotes a reflecting surface of the reflecting mirror 1, which comprises a concave surface, a convex surface, an aspherical surface, and the like. Reference numeral 2 denotes a substrate, which holds the reflecting mirror 1.
Reference numeral 3 denotes an adhesive member, which fixes the reflecting mirror 1 to the substrate 2 by bonding or fusing. Reference numeral 4 denotes a substrate supporting member, which supports the substrate 2 and fixes it to a part of a housing (not shown).

In this embodiment, the reflector 1 and the substrate 2 are made of the same material. The linear expansion coefficient of the bonding member 3 is different from the linear expansion coefficients of the reflecting mirror 1 and the substrate 2.
In this embodiment, the coefficient of linear expansion of the reflecting mirror 1 and the substrate 2 is 5 ×
10 ⁻⁸ [/ K], and the linear expansion coefficient of the adhesive member 3 is about 3
× 10 ^-4 [/ K]. The longitudinal elastic modulus of the adhesive member 3 is 1/100 of that of the reflecting mirror 1 and the substrate 2.
Very small, 0 or less.

In this embodiment, the longitudinal elastic coefficient of the reflecting mirror 1 and the substrate 2 is about 9200 [kgf / mm ² ], and the longitudinal elastic coefficient of the bonding member 3 is about 1 [kgf / mm ² ]. In the present embodiment, when the reflecting mirror 1, the substrate 2, and the bonding member 3 are deformed due to, for example, a temperature change among the environmental changes, the reflecting mirror 1
And the substrate 2 undergo a similar deformation, and the adhesive member 3 causes a greater deformation than the reflecting mirror 1 and the substrate 2. However, since the longitudinal elastic modulus of the adhesive member is very small as compared with that of the reflecting mirror 1 and the substrate 2, the force exerted on the reflecting mirror 1 and the substrate 2 is small, and the reflection surface 1a of the reflecting mirror 1 is affected by the change in surface. The effect is small.

In this embodiment, by adopting such a configuration, a highly accurate reflecting surface is maintained even in an environment where a temperature change occurs. In addition, as a material of the reflecting mirror 1 and the substrate 2, especially when it is necessary to maintain high accuracy with respect to a temperature change,
Low expansion metal materials such as invar alloys, low expansion glass, glass ceramics, ceramics and the like are suitable. If higher accuracy is required, it is preferable to select an adhesive having a smaller longitudinal elastic modulus of the adhesive member 3.

In this embodiment, the center thickness of the reflecting mirror 1 and the thickness of the substrate 2 are set to be substantially the same (difference within 10%). Thereby, even when the linear expansion coefficient of the adhesive member or the fusion portion of the bonding surface between the reflection surface and the substrate is different from the linear expansion coefficient of the reflection mirror and the substrate, when the temperature changes, the reflection mirror is There is no difference in force generated between the substrate and the substrate, so that a surface change is unlikely to occur on the reflection surface, and the reflection surface is maintained with high accuracy.

Next, another embodiment of the present invention will be described. The appearance of the reflector holding device is the same as that shown in FIG.

(A1) In the present embodiment, the reflector 1 and the substrate 2 are made of a material having substantially the same linear expansion coefficient. For example, the difference between the linear expansion coefficient of the reflector and the linear expansion coefficient of the substrate is set to 1 × 10 ⁻⁷ or less. Specifically, the linear expansion coefficient of the reflecting mirror 1 is 5 × 10 ⁻⁸ [/ K], the linear expansion coefficient of the substrate 2 is 4.8 × 10 ⁻⁸ [−K], The expansion coefficient is about 3 × 10 ⁻⁴ [/ K].

In the above arrangement, since the difference between the coefficient of linear expansion of the reflecting mirror and the substrate is small, the difference in the amount of deformation between the reflecting mirror and the substrate is small when a temperature change occurs. The force generated between the substrate and the substrate is reduced, so that the surface is unlikely to change on the reflection surface, and the reflection surface is maintained with high precision.

(A2) Also, the adhesive member 3 whose longitudinal elastic modulus is much smaller than that of the reflecting mirror 1 and the substrate 2 is used. For example, an adhesive having a longitudinal elastic coefficient of 1/1000 or less of the longitudinal elastic coefficient of the reflecting mirror 1 is used as the adhesive member 3. Specifically, the longitudinal elastic coefficient of the reflecting mirror 1 is about 920
0 [kgf / mm ² ], the longitudinal elastic coefficient of the substrate 2 is about 6900 [kgf / mm ² ], and the longitudinal elastic coefficient of the adhesive member 3 is about 1 [kgf / mm ² ].

In the above configuration, when a temperature change occurs, a force generated due to a difference in a linear expansion coefficient between the reflecting mirror and the substrate and the adhesive member becomes small, whereby the reflecting surface is hardly changed. The reflection surface is maintained with high precision.

In particular, since the longitudinal elastic modulus of the adhesive member is small, the force generated between the reflecting mirror and the substrate in the adhesive layer is reduced, so that the reflecting surface is hardly changed, and the reflecting surface can be formed with high precision. I keep it.

(A3) In the present invention, the rigidity of the reflecting mirror 1 is made equal to or greater than the rigidity of the substrate 2 in order to suppress the deformation of the reflecting surface of the reflecting mirror 1 to be small. In this embodiment, the longitudinal elastic modulus of the reflector 1 is E ₁ , and the thickness (center thickness) is t.
₁ , if the longitudinal elastic modulus of the substrate 2 is E ₂ and the thickness is t ₂ ,
Bending rigidity relates to the adhesive surface is E ₁ × t ₁ ³ by the reflector 1, a E ₂ × t ₂ ³ in the substrate 2. In the present embodiment, the thickness t ₁ of the reflecting mirror 1 is set to satisfy t ₂ × (E ₂ / E ₁ ) ^1/3 ≦ t ₁ .

In the above configuration, since the difference between the coefficient of linear expansion of the reflector and the substrate is small, the difference in the amount of deformation between the reflector and the substrate becomes small when a temperature change occurs. In addition, the bending rigidity of the bonding surface of the reflecting mirror is equal to or greater than the bending rigidity of the bonding surface of the substrate, whereby a change in the surface of the reflecting surface hardly occurs, and the reflecting surface is maintained with high precision.

(A4) In the present embodiment, in order to maintain higher accuracy, a material is selected so that the difference between the linear expansion coefficients of the reflector 1 and the substrate 2 is reduced, and the reflector 1 has a longitudinal elastic modulus. It is preferable to use a material having a large modulus of elasticity and to use a bonding member 3 having a smaller longitudinal elastic modulus.

[0025]

As described above, according to the present invention, as described above, the material and the center thickness of the reflector, the material of the substrate for fixing and holding the reflector, and the material of the adhesive member for bonding or fusing the reflector to the substrate are provided. By appropriately setting such factors, it is possible to achieve a reflecting mirror holding device suitable for a high-precision reflecting optical system in which the shape of the reflecting surface changes little even if there is an environmental change.

[Brief description of the drawings]

FIG. 1 is a perspective view of a main part of a first embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reflecting mirror 1a Reflecting surface 2 Substrate 3 Adhesive member 4 Substrate support member

Claims (5)

[Claims] When the reflector is fixedly held on a substrate by bonding or fusing with a bonding member, the material of the reflector and the substrate are made the same, and the center thickness of the reflector and the thickness of the substrate are substantially equal. A reflector holding device characterized by the same. 2. When the reflecting mirror is fixed or held to the substrate by bonding or fusion bonding with an adhesive member, an adhesive having a longitudinal elastic coefficient of 1/1000 or less of the longitudinal elastic coefficient of the reflecting mirror is used as the adhesive member. A mirror holding device. 3. When the reflecting mirror is fixed or held to a substrate by bonding or fusing with an adhesive member, a difference between a linear expansion coefficient of the reflecting mirror and a linear expansion coefficient of the substrate is 1 × 10 ⁻⁷ or less. A reflector holding device, characterized in that: 4. When the reflecting mirror is fixed or held to the substrate by bonding or fusing with a bonding member, an adhesive having a longitudinal elastic coefficient of 1/1000 or less of a longitudinal elastic coefficient of the reflecting mirror is used as the bonding member. A reflector holding device, wherein the difference between the coefficient of linear expansion of the reflector and the coefficient of linear expansion of the substrate is 1 × 10 ⁻⁷ or less. 5. When the reflecting mirror is fixed and held on the substrate by bonding or fusing with an adhesive member, the longitudinal elastic coefficients of the reflecting mirror and the substrate are E ₁ and E ₂ , respectively, and the center thickness of the reflecting mirror is t. _1. A reflecting mirror holding device, which satisfies a condition of (E ₂ / E ₁ ) ^1/3 × t ₂ ≦ t ₁ when the thickness of the substrate is t ₂ .