Computer-generated hologram for optical testing: a review

The computer generated hologram, or CGH, is the current de facto standard for accurate surface figure measurements of aspheres and freeforms. In this paper we will go over the history of the CGH technology development: from the birth of the holography to the invention of computer generated hologram; from early application of the CGH in testing aspheric surfaces to the development of precision fabrication techniques; from use of the CGH as null lens to more innovative applications testing and aligning optical systems. Dr. Wyant is a pioneer in the early development of the technology. His specific contributions will be introduced in detail. Efforts underway to expand the CGH use are also described.