Photometric device

摘要

A filter for compensation of spectral sensitivity is provided in front of a light receiving element through a light shielding tube. A light source emitting such light as having wave length characteristics which fall within a sensitive wave length zone of the light receiving element yet fall outside of transmitting wave length zone of the filter is provided between the filter and the light receiving element. Light from outside irradiates the light receiving element through the filter while light from the light source is so controlled as irradiating the light receiving element but not leaking through the filter to outside, so that the light from the light source can irradiate the light receiving element without any relationship with the irradiation of outside light on the light receiving element.