Design Of Achromatic Prisms for Broadband Risley Prism Devices

A primary concern of any device that uses prisms is the fact that prisms are inherentlydispersive. Risley prism optical steering devices are made of two or more prisms rotatedabout a common axis. Dispersion is the fact that any homogeneous glass will refract eachwavelength differently because the index of refraction of a material is not constant acrosswavelength. Risley prisms have other positives that broadband systems would like to makeadvantage of, and dispersion is their primary roadblock.This paper will investigate two possible solutions to the issue of dispersion in prisms.Examples will be generated for the visible, short-wave infrared, mid-wave infrared, andlong-wave infrared broadbands of each dispersion removal method. Lastly, a real worldprism using one of these methods was tested.