Patent ID: 8648289

Claim:
A device for detecting small quantities of light, comprising a first CCD or CMOS electronic image converter having a large number of light-sensitive cells for detecting photons representing the small quantities of light and for supplying a readout signal, and a processing circuit for processing the readout signal to a measurement signal representing the quantity of received photons, wherein the device comprises at least one second electronic image converter which is the same as the first electronic image converter and which is shielded from light; the processing circuit is also connected to the second electronic image converter and is adapted to compensate the readout signal of the first electronic image converter with a readout signal of the second electronic image converter; the first and the second image converters are thermally closely coupled to each other; and for each image converter, readout signals coming from any of the light sensitive cells of said image converter are respectively added together either by the processing circuit or by said image convertor for an adjustable period of time.