Interferometric testing of steep cylindrical surfaces with on-axis CGHs

We present a new approach for testing cylindrical optical surfaces using a Null-test. We suggest using a Computer Generated Hologram (CGH) in combination with a Transmission Sphere. It is shown that in such an optical layout the period of the diffractive structure is larger than in the case of a conventional scheme using a collimated beam. Therefore, this kind of hologram enables the test of cylinder surfaces with higher numerical apertures.