Patent ID: 8692669

Claim:
A constant optical output illuminator system to enable reliable, long-duration, low-light imaging and data capture for surveillance and security applications, comprising an array of LEDs, LED power supply circuitry, and output feedback and compensation circuitry, in which: a) a photodetector circuit provides a voltage signal proportional to an amount of light falling on at least one photosensor and the voltage signal is fed to a drive control circuit that supplies electrical current to the LEDs, to achieve a desired level of optical output commensurate to a voltage setpoint of the photosensor in the photodetector circuit; and b) the output feedback and compensation circuitry adjusts the optical output from the LEDs to compensate for voltage variations in the current supplied to the LEDs, for temperature variations that affect the optical output of the LEDs, for component tolerances in the power supply circuitry and in the LEDs, and performance degradation of the LED power supply circuitry and of the LEDs.