Hologram Interferometer for Null-testing and Measuring Paraboloidal Mirror Configuration

Abstract

A new type of hologram interferometer for null-testing and measuring a paraboloidal mirror configuration is proposed. In the interferometer a hologram causes a spherical reference wavefront which interferes with a spherical wavefront reflected by a paraboloidal mirror under test. The method to calculate the amount of configuration error of a paraboloidal mirror from the interferogram is also proposed. Almost straight and equally spaced tilt fringes obtained in the experiment for a commercial on-axis paraboloidal mirror shows the interferometer is useful.