其中 MTF 的量測精度取決於 Wavefront Sensor 的波前量測精度與計算中近似造成誤差，由於是以傅氏轉換的方式去計算，所以其頻率解析度可以到無限小，但相對地計算量也會增加；至於焦平面的量測精度則是取決於Wavefront Sensor 的量測精度，以本實驗為例，其量測精度為3um。;In the Optical manufacturing industry, the reason that affects the image quality of Lens is not only caused by the surface processing error and decenter and tilt of assembly, but also the alignment error between the focal plane of lens and sensor or film. This misalignment will cause the image to become blurred. And The Modulation Transfer Function(MTF) is the most widely used analysis method to evaluate the image quality.
This thesis proposes to use the rotating stage to rotate the lens to be tested, and use the Shack-Hartmann Wavefront Sensor to measure its wavefront profile in different field and at different azimuths, and we can use the wavefront profile to calculate the focusing position of beam, and then use some experiment to calculate the center and vector of the axis of rotation, and finally get the focal plane profile of the Lens after the coordinate conversion, and we can also obtain the modulation transfer function by using Fourier transform and coordinate conversion on the measured wavefront, beam radius and focus position measured by wavefront sensor.
