JPS6416906A - Displacement gage utilizing laser light - Google Patents

Abstract

PURPOSE:To improve the resolution of a displacement gage by arranging an image sensor so that images formed through a light receiving lens at the farthest and nearest points within a displacement measurement range are at due positions on the image sensor where the farthest and nearest points are image-formed. CONSTITUTION:The photodetection lens 2 has the same focal length (f) and photodetection angle theta with a conventional lens and is so arranged that the optical axis L1 of reflected light when a surface 4 to be measured at the farthest measurement point (c) from a laser 1 runs in the center M1 of the lens 2. Further, the image sensor 3 is so arranged that the length l between the image formation point c' on the sensor when the surface 4 to be measured is at the measurement point (c) and the image formation point a' on the sensor 3 when the surface 4 to be measured is at the nearest measurement point (a) to the laser 1 is equal to the length l of conventional arrangement. Consequently, the angle beta1 between the sensor 3 and optical axis L1 is larger than a conventional angle and the high-resolution is therefore obtained.