| Non-rotationally symmetric optical aspheric surface such as cylinder etc, have unique optical properties, Which have been widely applied in laser, astronomy and other advanced optics system. But because of the non-rotational symmetry characteristics, there didn’t have accurate absolute test method to measure these surface. The computer generated hologram (CGH) can produce the wavefront in any shape, which can realize null-test of complex optical element, but the system error and reference error limits the detection precision of the null-test which based on the CGH. In order to improve the testing accuracy, this paper discuss the conjugate differential method which can complete the absolute test of Non-rotationally symmetric optical aspheric surface, in terms of cylinder. The main research contents are as follows:Accomplish the design of CGH using in cylinder compensation, build interference measuring device, and realize the interference null-test of cylinder. At the same time, the Chebyshev-polynomial is adopted to detect the aberration, and separated adjust error in the process of null-testing.Reconstruct the surface with three kinds of Difference wave-front reconstruction algorithm during the simulation. And compared result with differential method’s, the precision of differentia surface data is enhanced by conjugate differential method, thus the test reliability is improved. At the same time, analyze the influence on reconstruction precision.by superposition the error such as noise, adjust error ect.Using conjugate difference method based on the orthogonal bilateral symmetry position realize the absolute test of cylinder. Design the clamping adjusting mechanism to complete the cylinder’s installation and conjugate movement, and get the absolute surface. Compare the contour line in the absolute surface with Taylor Hobson contourgraph’s test result at the same position.The two results are almost the same, Their RMS value deviation is better than 1/40X, (λ=632.8 nm). |
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