Patent ID: 7715025

Claim:
An optical displacement measuring apparatus, comprising an objective optical system and a detection section, for introducing light from a light source through the objective optical system to an object to be measured, and detecting light reflected from the object to be measured in the detection section to measure a displacement of the object to be measured relative to the objective optical system, wherein; the objective optical system is an optical prism which includes a broad-area flat portion and a narrow-area flat portion, each of whose flat surface is perpendicular to an optical axis, and includes a connection surface for connecting the broad-area flat portion and the narrow-area flat portion; the optical prism being placed at a position where an apex angle side having the narrow-area flat portion is opposed to the object to be measured, to thereby introduce the light from a broad-area flat portion side through a narrow-area flat portion side to the object to be measured, receive light reflected from the object to be measured on the connection surface, and direct the reflected light toward the detection section.