[A monochromator system for the irradiation of biological material, utilizing interference filters and an electronically controlled 2.5 kW xenon arc].

A high pressure xenon arc lamp XBO 2500 W is used as a radiation source for the production of quantum fluxes of the order of 6 μEinstein/sec at λ=700 nm and of 2 μEinstein/sec at λ=400 nm. Wavelength selection between 300 and 900 nm is made by tandem interference filters of the band pass type (band width at half peak transmission approximately 16 nm), with a total transmission outside of passband<0.08%. The radiation load on the filters is reduced by the use of interchangeable selective mirrors. The front surface of the interference filters is cooled with de-ionized water (metal interference filters absorb more than 30% of the impinging visible radiation). Homogenity of irradiance is achieved by means of a "honeycomb condensor". A simple cascaded feedback system sensitive to changes in lamp current and irradiance keeps radiation intensity constant with time. Technical details including safety devices are given.