Visible-light sensor
Solems

Silicon based components are supplying electricity when placed under light. So, they can be used as optical sensors, to measure the light intensity in the visible and near IR range.
The short-circuit current of a silicon photodiode is directly proportional to the light intensity.

- Luxmeters and PAR sensors (Photsynthetically Active Radiation) : with amorphous silicon photodiodes which spectral response is a 350 - 750nm (or 400nm-750nm)
AGRONOMY, PHOTOMETRY, POSITION DETECTION, TWILIGHT SWITCHING...

- Solar radiation sensors : with crystalline silicon photodiodes which spectral response is 400 - 1100 nm METEOROLOGY, PHOTOVOLTAIC SYSTEMS CONTROL, AGRICULTURAL CONTROL UNITS...