The aspheric mirror can correct aberrations and improve imaging quality of optical system . M oreover using such mirror
can reduce the num ber of optical elem ents in an optical system and further reduce the weight and size of the system . In
order to improve the accuracy of aspheric mirror fabrication, there are many methods used to m easure aspheric mirror.
Am ong these methods, the most popular one is interferom etry which can m easure the surface with very high accuracy.
However, interferom etry commonly requires com plicated and expensive assistant optics, and its m easurem ent range is
limited. In order to measure aspheric mirror conveniently and effectively, we further evolve the well know n approaches
of 'Phase M easuring Deflectom ety'(PM D) to measure such surface.
In this study, we present a novel m ethod based on fringe reflection to m easure aspheric m irror. In the m easurem ent
process, the screen and the cam era are m oved along the mirror optical axis, respectively. Using the phase information of
the recording fringe patterns, for each cam era pixel, we can calculate the slope and coordinate of its corresponding point
on the surface to be tested. By integrating, the absolute height of the tested surface can be reconstructed. Com pared with
traditional PM D, this m ethod can m easure the absolute height of an aspheric m irror unam biguously and doesn't need
com plex calibration.