INVESTIGATION OF ACOUSTOOPTIC TUNABLE FILTER PARAMETERS FOR FAST SPECTROMETER APPLICATION

Ideally an acousto-optic tunable filter is capable for selecting a single optical wavelength from a broadband polychromatic light beam simply by its electronic tuning. In practice, however, both the wavelength resolution and the operating wavelength range of the filter are limited by its electric and optical properties. An experimental configuration of a computer-controlled, fast acousto-optic spectrometer, based on an acousto-optic tunable filter operating in the 400- to 800-nm visible range with an average resolution of 10 nm is constructed and studied. The spectrometer has been operated in broadband optical measurements, such as determination of transmission spectra of complex, multilayer optical thin films and also real-time, in situ monitoring of evaporation processes. During the experiments, an anomalous behavior of the filter was observed that seriously limited the performance of the filter in the blue region. Some requirements necessary for spectrometer application are summarized and theoretical and experimental results are given illustrating the existence and also the elimination of this anomalous behavior.