Diplopore heterodyne ineterferometer based on acousto-optic low-frequency difference phase shift

Abstract

The invention discloses a diplopore heterodyne ineterferometer based on acousto-optic low-frequency difference phase shift. The diplopore heterodyne ineterferometer employs acousto-optic frequency shifter heterodyne interference phase shift, a detector continuously acquires an interferogram of a same optical path, and no aligning of multiple interferograms is required. The measuring precision is further improved. Low frequency difference heterodyne interference and high speed camera continuous acquisition are employed to obtain more abundant information, thereby facilitating accurate phase calculation and noises suppression.

Description

technical field [0001] The invention relates to the field of optical technology, in particular to a dual-aperture heterodyne interferometer based on acousto-optic low-frequency difference phase shifting. Background technique [0002] The high-end optical equipment represented by the projection exposure system of the deep ultraviolet lithography machine poses great challenges to the processing of optical components and the integration of optical systems. Interferometer is an indispensable core detection equipment for high-precision optical component processing and optical system integration, and the detection accuracy requirements are constantly improving. [0003] The optical surface shape detection methods used in traditional optical processing include Hartmann sensor method, knife edge method and contour method. These methods have different disadvantages such as non-digital subjective interpretation or contact damage to the test piece, and it is difficult to achieve high ...

AI Technical Summary

Problems solved by technology

However, although the polarization phase-shifting method is anti-vibration, if multiple phase-shifting images captured at the same time need to be registered to solve the phase, it will inevitably bring matching errors; The accuracy is restricted, and the phase-shifting accuracy of several phase-shifting images is limited by the phase-shifting module, which directly affects the surface inversion accuracy

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