Patent ID: 9115977
Filing Date: 2015-08-25
Classification: G01B,G01M

Abstract:
1. A near-null compensator for subaperture stitching interferometry of aspheric surfaces, comprising: a pair of counter-rotating computer-generated hologram phase plates, wherein each of said phase plates has a phase function comprising two terms Z5 and Z7 of Zernike polynomials: wherein ρ is pupil coordinate of normalized radial, θ is pupil coordinate of angular angle, and a is a coefficient of Z 5 polynomials and b is a coefficient of Z 7 polynomials; wherein said a of each of said two phase plates are contrary numbers and said b of each of said two phase plates are contrary numbers, and said coefficients a and b are determined by aberrations of off-axis subapertures; and said phase plates are mounted on a pair of precision rotary center-through tables while rotational axes said of precision rotary center-through tables coincide with optical axes of said phase plates.