A noncontact optical proximity sensor which can measure the distance ranging from 10 mm to 40 mm is constructed which is based on the phase information of modulated light signal.
The sensor system is composed of two infrared LEDs as the light source, a photo TR for detecting the reflected light and hardware circuit to obtain the phase information.
The relationship between the phase information and the distance is derived for the mirror surface by considering the luminance intensity.
In this thesis, the phase information is calculated theoretically by the optic theory, and these results are compared with ones of experiment using the constructed sensor system.
As a result, the measuring accuracy of the sensor is about +±1 mm for the operating range, and the sensor is shown to be insensitive to materials of mirror surface.
This sensor is applied to the edge detection of welding groove.
