An intensity regulation system for a monochromator

A relatively inexpensive system is described which utilizes a commercial grating monochromator and external feedback electronics to regulate the output intensity as the wavelength is varied. In this system, a sample of the output intensity is taken by a photosensor with known spectral response. The output of the photosensor is then compared electronically with that of a preprogrammed function generator which cancels nonlinearities in the photosensor. The resulting signal is used to regulate the monochromator light source. System output intensity has been observed to be constant to within 5% from 4750 A to 12000 A using two gratings.