Measurement based on fringe reflection for testing aspheric optical axis precisely and flexibly.

A method based on fringe reflection is proposed to measure the optical axis of an aspheric mirror precisely and flexibly. In the measurement, a screen displaying a fringe pattern is moved along its normal direction, and a camera is located beside and observes the fringe pattern reflected via a tested surface. This method can test the optical axis of an aspheric mirror quantitatively before measuring the absolute height of the tested surface. And it can be combined with some presented methods that need to fit the aspheric mirror according to the optical axis to measure the surface. To validate the ability of this method, it is combined with one of the presented methods to measure absolute height of an aspheric mirror precisely and flexibly. Computer simulations and preliminary experiment validate the feasibility of this method.