An inexpensive optical reflective sensor was evaluated for possible use as a precision proximity sensor. The output signal of the sensor was measured as a function of the distance of a flat reflecting surface from the front glass window of the sensor. The experimental data support the hypothesis that the sensor may be used as a precision proximity sensor.
and Dagalakis, N.
Calibration of an Optical Sensor, Calibration of an Optical Sensor, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=823393
(Accessed September 25, 2023)