Fabry-Perot interferometer with personal computer control.

To record weak light scattering spectra with a Fabry-Perot interferometer, long measuring times are often necessary. For long term stability of the parallel alignment of the mirrors, a microcomputer controlled interferometer system has been developed for both single and multipass operation. The three piezo stacks, which are responsible for the alignment of the mirrors, are supplied from three digital-to-analog converters controlled by a personal computer. The test and correction steps of the mirror alignment are performed around two independent axes perpendicular to each other. A special function generator provides a nonlinear scanning ramp for the piezostacks, thereby allowing a temporally linear scanning of the Fabry-Perot.