Quad Cell PhotoDiode Positioning Sensor-snippet
From CISSTwiki
Keywords
Sensor, positioning, photodiode
Description
Quad Cell PhotoDiode Sensor accurately sense and read the position of, or the movement of, a light beam on the sensing area. Some can give you sub micron (1/4 micron) resolution.
http://www.pacific-sensor.com/pdf/quadrant.pdf
http://www.phreshphotonics.com/Quadrant%20Photodiode%20SiQu50-MDtshVer2.htm