Patent ID: 8520217

Claim:
A Talbot interferometer configured to measure a wavefront of light that has passed a test object, said Talbot interferometer comprising: a diffraction grating configured to divide the light that has passed the test object into a plurality of diffracted light fluxes; an image pickup device configured to capture an interference fringe formed by the plurality of diffracted light fluxes; a moving unit configured to move at least one of the diffraction grating and the image pickup device; and a controller configured to control the image pickup device and the moving unit, wherein the controller captures a plurality of interference fringes using the image pickup device while changing a distance between the diffraction grating and the image pickup device using the moving unit, obtains a spatial frequency spectrum of each of the plurality of interference fringes, selects one of the plurality of interference fringes based on amplitude values of a plurality of spatial frequency spectra, and obtains a wavefront of the light that has passed the test object, based on a selected interference fringe.