A Hartmann wavefront sensor employing different-time exposure comprises a spectroscope, an optical power density measurer, a step-by-step acquisition controller, a microlens array, a CCD (Charge Coupled Device) camera, a center-of-mass calculator and a wavefront restorer, wherein the optical power density measurer measures the optical power density of incident wavefront at first; the step-by-step acquisition controller calculates the exposure time of step-by-step acquisition of the CCD camera to a light spot array according to the characteristics of the optical power density of the incident wavefront and the response sensitivity of the CCD camera, and then controls the center-of-mass calculator to calculate the center of mass of the light spot array step by step after the completion of acquisition; and finally, the wavefront restorer restores the incident wavefront according to the center-of-mass matrix obtained by the center-of-mass calculator. The Hartmann wavefront sensor acquires the array of the light spots at the CCD camera step by step by different exposure time by means of the step-by-step acquisition controller, thereby improving the signal-to-noise ratio of light spot center-of-mass detection in a single sub-aperture when the incident light intensity is uneven, enhancing the accuracy of center-of-mass detection and providing a solution for restoring the incident wavefront with high accuracy under the condition with uneven lighting.
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