JPH0116081Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field]

The present invention relates to a cold light reflector that transmits infrared light and reflects visible light in an optical system.

[Conventional technology]

BACKGROUND OF THE INVENTION Cold light reflectors, which are interference filters that reflect visible light and transmit infrared light, are currently in use and well known, by depositing a multilayer dielectric film on the surface of a transparent glass. The feature of this reflector is that the mid-infrared light emitted from the light source passes through the glass and is radiated from the back surface, and only visible light is reflected, making it the best reflector for irradiating heat-sensitive materials. be.

[Problem that the invention attempts to solve]

The above-mentioned reflector also has the following drawbacks. First, the base material is glass, and this glass lacks thermal and mechanical strength, so if a high-output lamp is used as a light source, the reflector may be damaged due to heat. Lamps such as high-pressure mercury lamps and xenon lamps often explode during use. During the explosion, the reflector used was also damaged, as it is made of glass. In order to eliminate this drawback, the base body of the reflecting mirror may be made of metal. However, most metals have a high reflectance in the infrared region of the light source, as shown by curves l ₁ , l ₂ , l ₃ and l ₄ in Figure 4.
Even if a luminescent film is coated on the surface of this metal, a luminescent effect cannot be obtained. Here, in Fig. 4, the curve l ₁ is the reflectance of silver,
l ₂ is the reflectance of aluminum, l ₃ is the reflectance of copper, l ₄
is the reflectance of gold and l ₅ is the reflectance of a black object.

[Means to solve the problem]

In view of the above-mentioned points, the present invention involves forming the surface of a reflective mirror base made of metal black, and providing a coating layer made of a dielectric material on this black surface that reflects visible light and transmits infrared rays. This provides a cold light reflector with excellent thermal and mechanical strength.

【Example】

Embodiments of the present invention will be described below with reference to FIGS. 1 to 4. As shown in FIG. 1, a reflective mirror base 1 made of metal is formed of a rotating circular body with both ends open, and the inner surface of the reflective mirror base 1 is covered with a black surface 2 made of a black plating layer or the like. It is formed. A multilayer coating layer 3 made of a dielectric material that transmits infrared rays and reflects visible rays is provided on this black surface 2 to constitute the cold light reflecting mirror. If a light emitting unit 4 such as a xenon lamp, which is a light source, is placed at the focal point of the cold light reflector, visible light will be reflected, while infrared rays will be transmitted through the cold light film formed by the coating layer 3 and absorbed by the black surface 2. will be done. That is, the curve _l6 in FIG. 2 shows the transmittance T of the light at the wavelength λ in the coating layer 3.
In the vicinity of λ=0.4 μ (microns), the transmittance T is 80%, and when λ>0.8 μ, the transmittance T is around 90%, and the infrared transmittance increases. Moreover, the curve _l7 in FIG. 3 shows the reflectance R for the wavelength λ of light in the coating layer 3. In the region of λ=0.4 to 0.75μ, the reflectance R>80%, and in the region of λ>0.9, the reflectance R=10. %, and the reflectance of infrared rays becomes extremely small. Although the embodiment shown in FIG. 1 describes the case of a concave reflecting mirror, the present invention can of course be applied to convex and flat reflecting mirrors. This refers to layers of alternating coatings of dielectric materials with low refractive index and low refractive index.

[Effect of the idea]

The visible part of the cold light reflective film reflects the same whether the base material is glass or metal, but the infrared light passes through the cold light film, is reflected by the metal surface, passes through the cold light film again, and becomes visible light. reflected in the same direction,
Although no cold light effect can be obtained, the principle of the present invention is extremely simple, and the purpose is to make the metal surface shiny and black. In other words, the infrared rays transmitted through the cold light film are absorbed by the black surface, while metal has good thermal conductivity, so the absorbed heat is radiated from the back surface and can be avoided from thermal effects. Since forced cooling is sufficient, the present invention has the effect of providing a high-performance cold light reflector with excellent thermal and mechanical strength.

[Brief explanation of the drawing]

Figure 1 is a quick sectional view showing an embodiment of the present invention;
The figure is a transmittance characteristic diagram of the cold light film with respect to the wavelength of light, FIG. 3 is a reflectance characteristic diagram of the same as above, and FIG. 4 is a reflectance characteristic diagram of the metal and black surface parts with respect to the wavelength of light. In the figure, 1 is a reflecting mirror matrix, 2 is a black surface, and 3 is a coating layer.

Claims (1)

[Scope of utility model registration request] A cold light reflector characterized in that the surface of a reflective mirror base made of metal is formed black, and a coating layer made of a dielectric material that transmits infrared rays and reflects visible rays is provided on the black surface.