Device for the individual adjustment of the intensity of several spectral lamps

A device for the individual adjustment of the intensity of a plurality of spectral lamps, the radiation of which is combined into a common ray path comprising:

• (a) modulating means for the modulation of emission from each of the spectral lamps with a different frequency,
• (b) beam-splitting means for extraction of a part of the total radiation that is inserted into the common ray path,
• (c) photoelectric receiver means for the generation of an electrical signal which is proportional to an intensity of the extracted radiation,
• (d) electronically tunable frequency filter means which is tuned to respective modulation frequencies of the spectral lamps and connected to an output of said photoelectric receiver means,
• (e) regulator means comprising a phase-locked loop, an automatic gain control, and a power amplifier having differently modulated outputs for operation of the spectral lamps, and
• (f) circuitry means for alternating tuning of said frequency filter means to the modulation frequencies of the spectral lamps and switching of a signal of the automatic gain control to a correspondingly modulated output of the power amplifier.