CGH testing for large concave surface

For the large concave surface, the traditional testing method is null tests by using refractive compensator. However, not only it is difficult to align the optical elements of the system, but also it is expensive to fabricate them. In this paper the CGH fabricated on the compensator lens surface which is utilized in system to substitute the traditional compensator is discussed, and the practical optical parameters are given.For the sample surface with the aperture of 950 mm, testing result of P-V is 0.024λ.