| 摘要 |
<p>PURPOSE:To constitute an optical separator having a relief type diffractied grid, so that a separated luminous flux is not influenced by a stray light beam, by specifying a shape of the diffracted grid. CONSTITUTION:An optical separator 25 consists of transparent substances 18, 18 on whose surface a relief type diffracted grid has been engraved, adhesive agents 19, 19 having the same refractive index, and a transparent substance 20 made of the same quality of material. On the diffracted grid surface is formed a reflection fiml 21. When a light beam 22 from an object is made incident to the optical separator 25, a part of said light beam becomes a reflected diffraction light beam 24 by the reflection film 21, and the residual passes through. In case when optical separators 25 (35) have been applied to a photometric system of a single-lens reflex camera so that the diffraction light beam and the transmission light beam are led to a photodetector 8 and an eyepiece part, respectively, an incident light beam 34 from the eyepiece part is diffracted by the film 21, proceeds to the photodetector 8, and becomes disturbance for an exact photometry. The disturbance light beam is totally reflected by a surface 40 under the condition as shown in the expression. Provided that, DELTAtheta, thetac and alpha, beta show an extended half angle in the optical separator of the incident light beam, a critical angle, and angles shown in the figure, respectively.</p> |
