| 摘要 |
PURPOSE:To ensure the photometry for a subject of low brightness and to realize an attachment of such photometric device to a conventional camera mechanism with no serious modification, by leading effectively the light to a photodetector by means of a light condenser plate of a microstructure and at the same time increasing the light condensing area up to several times as much as a conventional area. CONSTITUTION:A submirror 14 is set at the back of a transmitting part 13 of a mirror 7, and the light 15 is turned to a plate type condenser optical element 16. A part of the luminous flux transmits through the part 13 and is made incident to a photodetector 17 through an optical path shown in the diagram to be measured. The element 16 contains a reflecting surface 21 at the end face of a transparent substrate 20 and grating lines 22-1-22-3 of diffraction grating on the lower surface, respectively. The incident light 23 is reflected by an end mirror 21 and then fully reflected to both upper and lower surfaces 24 and 25 of the substrate 20 to be sent to the photodetector 17. At the same time, the incident light 26 goes to the detector 17 in the same way by a line 22. The lines 22 are condensed onto the detector 17 by curved grating lines. |
