OPTICAL MEASURING INSTRUMENT

PURPOSE:To process light which is transmitted through a body to be inspected or a signal which is converted photoelectrically as signals of straight traveling light and scattered light separately by providing a means which opens and closes a circuit for the signal of an optical path or photoelectrically converted signal. CONSTITUTION:An ultrasonic measurement part 10 measures the time required for the light to travels through the body 100 to be inspected linearly and an optical switch 5 close the optical path between the body 100 to be inspected and a photoelectron multiplier tube 6 according to the transmission time of the light found by the ultrasonic measurement part 10 to send only the light which travels in the body 100 to be inspected straight to the photoelectron multiplier tube 6. Therefore, it can be judged whether the quantity of the transmitted light is varied owing to variation of a part along the optical path where the light travels straight, and the measurement accuracy can be improved. Further, when this device is applied to an optical CT device, the resolution can be improved.