PURPOSE: To reflect reflected light from a reference mirror in the same direction as the incident direction by integrally providing a condenser lens the focal point of which lies near the position of the reference mirror with the reference mirror in front of the reference mirror.
CONSTITUTION: The laser beam emitted from each laser light source 31 and 32 is made incident to a beam splitter 36 by which the laser beam is split into P1 and P2. The P2 is condensed to the reflecting surface 38a of an object 38 to be measured through a condenser lens 37, again made incident to the splitter 36, and reflected by the splitter 36 toward a condenser lens 39. The P1' on the other hand, is condensed to the reflecting surface 42a of a reference mirror 42 through a condenser lens 41, made incident to the splitter 36, and advances toward the lens 39 after passing through the splitter 36. The reflected light rays P1 and P2 become interference light rays and are received by the light receiving surface 40a of a light receiving section 40 through the lens 39. By moving the mirror 42 forward and backward along its optical axis so that interference fringes can be formed on the light receiving surface 40a, the distance to the mirror 38 to be measured is measured.
MINEGISHI ISAO
KAWASHIMA HIROYUKI
Next Patent: VIDEO TYPE THROTTLE MACHINE