Test of Large off-Axis Aspheric Surface with CGH

We are working on a 1.45m off-axis asphere with deep aspherical shape. A null-lens was designed, but because of distortion and map error of asphere, areas far from axis cannot be measured by interferometer. We analyzed distortion and then designed a CGH. Because of the distortion difference between CGH and null-lens, areas that cannot be measured by null-lens now can be measured by CGH. Then we combine both result to get full wavefront map.