The invention discloses a common-optical-path point-diffraction synchronous phase-shift interferometer using lenses for light splitting. The interferometer comprises a testing optical path, a 4f system optical path, a light splitting optical path and a phase-shaft optical path arranged successively along the optical path. The testing optical path comprises a laser, a beam expanding system and a tested sample arranged successively in the common optical axis, and obtains measured information; the 4f system optical path comprises two Fourier-lens-and-reflector groups positioned in two arms of an interference system respectively, a linear-polarization pinhole diffraction plate is arranged in a confocal position of two Fourier lenses, and reference light and test light are obtained; the light splitting optical path comprises a lambda/4 waveplate and three light splitting lens groups, each of the reference light and test light is split into four beams at equivalent light path; and the phase-shaft optical path comprises a beam compressing system, a polarization array and a detector arranged successively in the common optical axis, and the light is received by the detector after beam compression, and four interference images are formed. According to the invention, pinholes are used for form spherical waves, the measuring precision is high, a common-optical-path system is included, the structure is compact and the anti-vibration performance is high.

Common-optical-path point-diffraction synchronous phase-shift interferometer using lenses for light splitting

The invention discloses a spatial beam splitting coaxial Fizeau type synchronous phase-shift interferometer and a measuring method thereof and belongs to the optical interference measurement instrument field. The interferometer comprises a point light source, a beam splitting assembly thereof, a Fizeau type main interferometer and a beam splitting and imaging assembly. The method includes the following steps that: spherical waves emitted by the point light source are split into four light beams through the beam splitting assembly, and the four light beams enter the main interferometer, namely, one point light source is duplicated into four point light sources through the beam splitting assembly; distances between the four point light sources on the focal plane of the collimation objective of the main interferometer and an optical axis are adjusted; different phase shifting quantities are introduced into the interference of a reference plane and a test plane; and four clearly-imaged phase-shift interference patterns can be obtained simultaneously on one CCD through the beam splitting and imaging assembly. The interferometer of the invention has the advantages of low cost, excellent seismic performance, easiness in operation and the like, and can be applied to fields such as real-time high precision detection of optical components.

Spatial beam splitting coaxial Fizeau type synchronous phase-shift interferometer and measuring method thereof

The invention discloses an ePIE phase recovery algorithm based on entrance pupil scanning modulation. Based on a built entrance pupil scanning modulation overlapping imaging device, a variable-size rectangular box is adjusted to change the entrance pupil, and illumination light is modulated to get diffraction patterns under the condition that no to-be-tested sample is added and diffraction patterns under the condition a to-be-tested sample is added. An extended aperture is introduced to replace the actual aperture. Finally, the phase information of a to-be-tested sample is obtained using the ePIE algorithm twice. The ePIE phase recovery algorithm of the invention has such advantages as imaging without lenses, wide field, fast convergence, and high stability.

ePIE phase recovery algorithm based on entrance pupil scanning modulation

The invention relates to a digital Moire fringe phase extraction method based on nonlinear optimization, belonging to the technical field of optical measurement and image processing. According to the method, a Moire synthesis light intensity distribution graph mathematical model is established, a fringe phase is used as an optimization variable, with actual Moire synthesis graph light intensity distribution as an optimization target, phase continuity is taken as a boundary condition, through nonlinear optimization calculation, the light intensity distribution of the mathematical model is equal to the light intensity distribution of an actual Moire synthesis graph, and the fringe phase at that time is the Moire fringe phase of the actual Moire synthesis graph. According to the method, the Moire fringe phase can be obtained without low pass filtering, a filtering error in a spectrum aliasing condition can be avoided, and a phase measurement precision is improved.

Digital Moire fringe phase extraction method based on nonlinear optimization

The invention discloses a method for eliminating axial distance error between an object and a CCD through a self-focusing iterative algorithm. The method comprises the following steps: establishing anaxial distance error model through a Fresnel diffraction theory, and calculating axial distance through measurement of resolution of amplitude of a restored object, that is, in the laminated imagingprocess, transmitting reconstructed images to axial-distance-different planes through Fresnel diffraction integral and calculating a Tamura coefficient at each plane, the Tamura coefficients being resolution evaluation indexes, and when the Tamura coefficient reaches a maximum value, the generated restored image being clearest; and serving the axial distance corresponding to the place as a new axial distance for the next iteration, and repeating the process until the axial distance converges, and thus accurate axial distance is obtained. The method is good in correction effect for the axial distance errors in the laminated imaging process, is fast in operation speed and is high in image restoration resolution; and the method can be applied to the field of biological microscopy and opticaltest and the like.

Method for eliminating axial distance error between object and CCD through self-focusing iterative algorithm

The invention discloses a device and method for measuring the curvature radius of a spherical mirror based on a pinhole type point diffraction interferometer. Double quantitative defocusing is realized through sequentially inserting two parallel flat plates with different thicknesses in an interfering cavity of the pinhole type point diffraction interferometer. When the parallel flat plates are not placed in a test optical path, wavefront data W0 are obtained through phase shifting measurement. After the two parallel flat plates with different thicknesses are respectively placed in the test optical path, two different wavefronts W1 and W2 are obtained through phase shifting measurement, and the calculating formula of the curvature radius of the spherical mirror is derived through the difference between the defocusing coefficients of the W1 and the W0, the difference between the defocusing coefficients of the W2 and the W0 and a Gaussian imaging formula. When the non-contact type measurement method is adopted, the damage of the surface of the spherical mirror is avoided, a feasible method is provided for the non-destructive measurement of the curvature radius of the spherical mirror with a large numerical aperture. Meanwhile, the method is suitable for the surface shape test of the spherical mirror with the large numerical aperture.

Device and method for measuring curvature radius of spherical mirror based on pinhole type point diffraction interferometer

The invention discloses an off-axis phase waveband plate-based interference microscopic detection apparatus including a 13.5nm extreme ultraviolet light source, a focusing waveband plate, a five-dimensional precision micro adjustment table, an off-axis waveband plate, an optical fiber point diffraction device, an extreme ultraviolet bright field CCD and an extreme ultraviolet dark field CCD. The off-axis waveband plate is a hollow phase type structure, can realize modulation of + 1 level diffraction light, when the light is incident on sample surface, scattering and reflection occur simultaneously, the off-axis waveband plate takes effect on reflected light and scattered light, the reflected light is modulated into axial focusing, and the scattered light is reflected to the dark field CCD; the optical fiber point diffraction device provides reference light for testing light, interference of the reference light and the testing light is realized, an interferogram enters the bright field CCD, and the interferogram is interpreted by a computer for reduction of contour information of a to-be-tested sample. The off-axis phase waveband plate-based interference microscopic detection apparatus has the advantages of simple structure, good vibration resistance, high precision, low system cost, simultaneous bright field and dark field analysis and timely positioning and analysis of phase defects, and can obtain defect contour information.

Off-axis phase waveband plate-based interference microscopic detection apparatus

The invention discloses a lens focal length measuring device and method based on a Fizeau interferomenter. According to the lens focal length measuring method, two parallel flat plates different in thickness are sequentially inserted into an interference cavity in the lens focal length measuring device for introducing axial displacement of an object point and a image point, and the lens focal length is measured. The lens focal length measuring method includes the steps that a glass flat plate is placed at the cat eye position, and when no parallel flat plate is placed in a test light path, the difference W1-W0 of test wavefront data W1 and reference wavefront data W0 is obtained through phase shift interferometry; the two parallel flat plates different in thickness are respectively arranged in the test light path, and the wave difference W2-W0 and the wave surface W3-W0 which are different from each other are obtained through phase shift interferometry; the wave difference W2-W1, the wave difference W3-W1 and a Gaussian imaging formula are obtained through calculation by adopting a wavefront difference algorithm, and a calculation formula of the lens focal length is derived. Damage to the surface of a lens is avoided by the adoption of the non-contact measuring method, and the lens focal length measuring device and method are suitable for measuring positive and negative lens focal lengths.

Lens focal length measuring device and method based on Fizeau interferomenter

The invention discloses an optical heterogeneity measurement device and method based on a dual wavelength fizeau interferometer With the dual wavelength fizeau interferometer, interferograms of a reference light wave and a light wave reflected by the front surface of a to-be-tested flat mirror are sequentially collected, and wavefront aberration data [delta]W11(x,y) and [delta]W21(x,y) corresponding to wavelengths [Lambda]1 and [Lambda]2 are obtained by first phase shift measurement; interferograms of the reference light wave and a light wave passing through the to-be-tested flat mirror and reflected by the rear surface of the to-be-tested flat mirror are collected, and wavefront aberration data [delta]W12(x,y) and [delta]W22(x,y) corresponding to the wavelengths [Lambda]1 and [Lambda]2 are obtained by phase shift measurement; and a difference value is calculated by the wavefront aberration data corresponding to the wavelengths obtained by two-stepped measurement, and the optical heterogeneity of the to-be-tested flat mirror is obtained The invention does not require a standard reflector, and completely eliminates influences of the surface shape of the standard reflector on measurement results The measurement steps are simple, and the defects that the traditional absolute measurement method has tedious steps and is vulnerable to air disturbance are tackled

Optical heterogeneity measurement device and method based on dual wavelength fizeau interferometer

The invention discloses a Fizeau double-wavelength interference test device and a synthetic wavelength phase extraction method thereof During work under two wavelengths, a dichroic mirror is used to collect a single-wavelength phase-shifting interferogram Work under two wavelengths can be realized by only eliminating the chromatic aberration of part of optical paths Then, in view of the problem in the traditional double-wavelength phase-shifting interference test device that phase shifting error under different wavelengths is caused by PZT phase shifting, a way of synthetic wavelength-single wavelength phase processing is used to suppress the influence of phase shifting error under different wavelengths on synthetic wavelength phase and avoid calibration of phase-shifting step amount under two wavelengths The method can also be used to effectively measure the vibration and multiple-beam interference errors under different wavelengths As there is only the need to control the test precision under a single wavelength, synthetic wavelength phase data can be extracted quickly and easily by use of the method

Yuan Qun

Papers

Device and method for measuring curvature radius of spherical mirror based on pinhole type point diffraction interferometer

Off-axis phase waveband plate-based interference microscopic detection apparatus

Lens focal length measuring device and method based on Fizeau interferomenter

Optical heterogeneity measurement device and method based on dual wavelength fizeau interferometer

Fizeau double-wavelength interference test device and synthetic wavelength phase extraction method thereof