<title>Measurement of a convex secondary mirror using a holographic test plate</title>

Abstract

A 26-cm diameter aspheric convex secondary mirror was successfully measured using a holographic test plate. This measurement demonstrates the viability of the holographic test plate method for measuring convex aspheres. An opticai writer was built and used to demonstrate the ability to write precise holograms on large, curved substrates. The hologram written for this test was fabricated using a thermochemical method that does not require the use of photoresist. The accuracy of the holographic test is demonstrated with a comparison with data from an independent Hindle test.