Title:
OPTICAL SYSTEM FOR FOCUSING DETECTION
Document Type and Number:
Japanese Patent JPH03200207
Kind Code:
A
Abstract:
PURPOSE:To obviate the generation of erroneous distance measurement even if stray light infilters a prism by forming the non-effective optical path region of at least one prism surface which allows the transmission of the luminous flux passing the inside of the prism member and forming an object image or reflects the luminous flux as either of a light diffusing surface or surface coated with a light absorptive material. CONSTITUTION:The part A-B where the luminous flux from the subject does not pass in either of the case in which a joining material 11 is packed between an exit surface 10 and a photodetecting surface 7a or the case in which an air spacing is formed between the exit surface 10 and the photodetecting surface 7a is formed as the light diffusing surface 12 or the surface 13 coated with the light absorptive material. The stray light c is, therefore, shut off by this surface 12 or 13 and does not arrive at the photodetecting surface 7a. Thus, the arrival of the stray light at the photodetecting surface 7a of a photoelectric converting element is obviated and, therefore, the erroneous distance measurement is prevented.
Inventors:
INAHATA TATSUO
Application Number:
JP34352689A
Publication Date:
September 02, 1991
Filing Date:
December 28, 1989
Export Citation:
Assignee:
OLYMPUS OPTICAL CO
International Classes:
G03B13/36; G02B7/30; G02B7/34; (IPC1-7): G02B7/30; G03B13/36
Domestic Patent References:
| JPS55115023A | 1980-09-04 | |||
| JPS6278518A | 1987-04-10 | |||
| JPS61129609A | 1986-06-17 | |||
| JPS57161714A | 1982-10-05 |
Attorney, Agent or Firm:
Taiji Shinohara (1 person outside)