Testing system based on computer-generated holograms(CGHs) can achieve high accuracy of aspherical measurement,
this paper studies a new method for testing convex aspheric surface-two CGHs. This method has an advantage in
resisting interference and needing no huge assistance surfaces. For a convex hyperboloidal mirror, such a testing system
has been designed and optimized in Zemax with the testing accuracy of prior to 0.015λ, and all of other disturbing rays
image outside of aperture with a radius of 0.8mm. Finally, the system errors are analyzed in detail and the results show
that this system can guarantee the testing accuracy of aspherics. In addition, this testing system can also measure off-axis
aspherics and free-form surfaces.