Acoustooptic filters for astronomical photometry: design and fabrication.

Using calculations based on the acoustooptic properties of the crystal material a procedure is outlined for the design of filters having a particular bandwidth specification and reduced sensitivity to the incidence angle of the input beam. Relevant aspects of the fabrication techniques are given. The optical performance of a prototype filter having a 0.5-2-nm bandwidth over the 400-700-nm tuning range based on the design methods outlined is satisfactory for the chosen application, but it is not optimum. Analysis of experimental and design data shows that this can be accounted for by an error in the specified angle of the crystal axis which is required to accuracy of some +/-0 5 degrees .