A dual-wavelength single-exposure interferometry method and system

Abstract

The present invention provides a dual-wavelength single-exposure interferometry method and system based on spatial carrier frequency phase shift. A monochrome black-and-white image sensor is used to record a dual-wavelength aliasing off-axis interferogram including spatial carrier frequency, and then the One of the interferograms is converted into multiple dual-wavelength phase-shifted sub-interferograms, and then the least squares phase extraction algorithm is used to simultaneously obtain two wrapped phases at a single wavelength, and then a simple subtraction operation can be used to obtain the composite wavelength lower phase. The feature of the present invention is that it proposes a large-scale single-exposure interferometry method. This measurement method has a simple device, but is stable and reliable, and has high precision. The most obvious advantage is that only one interferogram needs to be collected to realize two The phase shift under the wavelength expands the application field of the phase shift method, and it has a good application prospect in preventing environmental interference or dynamic phase measurement in phase measurement.

Description

technical field [0001] The invention relates to the field of optical interferometry or digital holography, in particular to a method and system for single-exposure dual-wavelength interferometry based on space carrier frequency phase shift technology. Background technique [0002] Optical interferometry technology uses the interference principle of light to record the phase information of the object to be measured in the form of interference fringes, and the phase of the object to be measured can be obtained by processing the interference fringes. Usually the use of single-wavelength measurement technology will encounter the problem of phase ambiguity caused by the fluctuation of the object to be measured beyond the measurement wavelength. The use of dual-wavelength measurement technology can generate a synthetic wavelength (equivalent wavelength) that is much larger than the original wavelength. , so as to avoid the problem of understanding the phase wrapping, and can reali...

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Problems solved by technology

[0003] In order to overcome the technical problems of phase ambiguity, low precision, high requirements for environmental stability and complex and time-consuming measurement process in the prior art when measuring large mutation objects, the present invention provides a technology based on space carrier frequency phase shift The single-exposure dual-wavelength interferometry method only needs to collect a dual-wavelength aliasing off-axis interferogram from a single black-and-white image sensor to simultaneously extract the wrapped phase at two wavelengths, and then use the frequency difference of the two wavelengths to generate Synthetic wavelengths to achieve the measurement of larger jump objects, the invention combines the advantages of the time domain phase shift method and the Fourier transform method, while maintaining the measurement accuracy of the time domain phase shift method, it expands the measurement range and reduces the Meet the requirements of environmental stability, reduce the acquisition time, and facilitate the realization of dynamic phase measurement

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