Interferometer for detecting point-diffraction wave aberration and its detection method

Abstract

The invention relates to a point diffraction wave aberration detection interferometer and detection method. The interferometer comprises a light source, a first splitter, a first light intensity and polarization regulator, a phase shifter, a second light intensity and polarization regulator, a point light source generation unit, an ideal wavefront generation unit, a to-be-detected optical system, a precise adjusting table, a small aperture light window device, a second splitter, a two-dimensional photoelectric detector and a data processing unit. The interferometer is advantaged in that measurement space resolution is high, interference fringe density is adjustable, multiple interference phase extraction algorithms such as phase shift and space carrier wave phase shift can be utilized, an interferometer system error can be calibrated, and interference contrast is adjustable.

Description

technical field [0001] The invention relates to the field of interferometry, in particular to a point-diffraction interference wave aberration detection interferometer and a detection method thereof. Background technique [0002] Waveform aberration is an important parameter to describe the performance of small aberration imaging optical system. The wave aberration of high-quality microscope objectives and space telescopes should be less than λ / 4PV or λ / 14RMS (λ is the working wavelength, and RMS is the root mean square value). The wave aberration of deep ultraviolet lithography projection objective lens and extreme ultraviolet lithography projection objective lens should be less than 1nm RMS. This puts high demands on wave aberration detection technology. [0003] The prior art (refer to prior art 1: Tang Feng, Wang Xiangchao, etc., point diffraction interference wave aberration measuring instrument and detection method, invention patent 201310126148.5) proposes a point d...

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Problems solved by technology

However, because this technical solution needs to place two point light sources on the object plane of the imaging system at the same time, due to the limitation of the spatial resolution of the photoelectric sensor, the two point light sources cannot be too far apart. Due to the noise problem of the light window of the point diffraction interferometer, a low The data measurement frequency band is limited by the pass filter, so that the measurement spatial resolution of the system is restricted (see prior art 2: Patrick P.Naulleau, Kenneth A.Goldberg, Dual-domain point diffraction interferometer, APPLIED OPTICS, 38(16), 3523-3533(1999).); Moreover, due to the use of dual-point light sources, the system cannot achieve zero fringe detection. When the phase-shift algorithm is used, it is more sensitive to noise factors such as vibration and phase shifter nonlinearity; on the other hand, the dual-point light source After the distance between point light sources is fixed, the number of interference fringes cannot be adjusted, and various interferometric data processing algorithms such as fringe carrier algorithm and space carrier phase shift algorithm cannot be flexibly used to improve the detection speed, which makes the use conditions of the interferometer subject to certain restrictions

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