| 摘要 |
PURPOSE:To eliminate the influence of temperature variation and to improve the precision by measuring the distance between a projecting and a photodetecting lens as a correcting value of distance arithmetic. CONSTITUTION:Light from a light source 1 is projected on a body to be measured by the projecting lens 2 through a half-mirror 7 and the spot of the emitted light is image-formed by the photodetecting lens 4 and detected by the 1st photodetector 5, whose output is sent out to a processing circuit 6 through a switch together with the signal of the 2nd photodetector 8 which photodetects reflected light from the mirror 7. Then, variation DELTAl in the distance between the mirror 7 and detector 8 with the ambient temperature is calculated from variation DELTAl of the signal of the photodetector 8, and the conversion coefficient used for the measured distance arithmetic by the detector 5 is corrected with the variation DELTAl. |
