Abstract

The acoustooptic tunable filter (AOTF) is an electronically programmable spectral filter with large optical throughput.¹ The small size, low weight, and rugged construction makes it well suited to spaceborne systems. One major deficiency of current AOTFs that limits its potential for system deployment is the high side lobes in the bandpass response. In principle these side lobes can be suppressed by suitable amplitude apodization of the acoustic excitation. Previous attempts have not yet produced acceptable results because of the difficulty of implementing the apodized transducer. Several apodization techniques were studied, including tapered dielectric coupling, segmented transducer, electrode shaping, and tapered transducer. A theoretical analysis of these apodization techniques were made and the bandpass responses were calculated using various choices of weighting functions. These techniques were experimentally investigated.

© 1991 Optical Society of America