Characterization of lenslet arrays for astronomical spectroscopy

Microlens arrays are now widely used in a variety of astronomical instrumen ts that require high performance. This paper describes the applications of microlenses in astronomical spectroscopy and discusses the necessary perfor mance requirements. A variety of optical tests, including high dynamic rang e point-spread function measurements and determination of encircled energy, were developed to characterize the performance of a variety of lenslet arr ays. Results are presented that indicate the best types of lenslet array fo r use for astronomical spectroscopy.