| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a displacement gauge capable of suppressing decrease in speed for changing a focal point even when a measurement range is enlarged on a measurement axis.SOLUTION: A displacement gauge 1 measures displacement of an object W to be measured on a predetermined measurement axis AX, and includes a polygon mirror 10 for successively deflecting light from a laser beam source 2 to a plurality of directions mutually different toward an object W to be measured; a second collimate lens 12 for converting each of the light deflected to a plurality of directions into the light parallel to one direction; a first concave mirror 21 for condensing the light parallel to one direction so as to focus at mutually different positions on the measurement axis AX and obliquely emitting the light for the measurement axis AX; a two-dimensional CCD8 for receiving the light reflected by the object W to be measured and condensed by a second concave mirror 22; and a control part. The control part measures the displacement of the object W to be measured based on information relating to a rotation angle of the polygon mirror 10 at the maximum amplitude point where an amount of light of the light receiving part becomes the maximum.</p> |
