Phase detection device and method for optical element

A phase-detection device for an optical element, wherein along the direction of the optical path the phase-detection device comprises:

• a light source, a beam collimator, a diffraction element and an imaging detector;
• the optical element to be detected is set between the filter and the diffraction element;
• the diffraction element comprises a mesh mask region and an array region segmented by the mesh mask region;
• the mesh mask region is used to block lights of a target wavelength;
• the array region comprises a first class of cell and a second class of cell, and the first class of cell and the second class of cell are alternatively arranged;
• the first class of cell is used to provide a first phase for the lights of the target wavelength, and the second class of cell is used to provide a second phase for the lights of the target wavelength;
• a phase difference between the first phase and the second phase is TC rad;
• the device further comprises a process;
• the process is communicatively connected to the imaging detector to determine a phase corresponding to the optical element according to an interference image recorded by the imaging detector.