Large Dynamic Range Phase Retrieval Method For Aspheric Interferometry

In modern optical system,aspherical optical elements can significantly improve the system image quality,expand the field of view,reduce the number of optical elements,reduce the volume and weight of the system,and have been widely applied.The high precision Aspheric surface measurement method,which has the versatility and can be used for on-line measurement,has important directive significance to the aspheric surface processing.Partial compensation interferometry method achevieve versatility by the multiplexing of partial compensator.Digital moire phase-shifting interferometry can extract phase from a single interferogram,which is suitable for on-line measurement.Theoretically,the requirements of versatility and on-line measurement can be met by combining partial compensation interferometry and digital moire interferometry.However,the dynamic range of the digital moire phase-shifting interferometry is limited,which limits the versatility the combination method.So it is very important to study how to extend the dynamic range of phase extraction process.Based on the partial compensation interferometry and the digital moire phaseshifting interferometry,this thesis studies the phase extraction method with the large dynamic range in aspheric measurement,and the specific work is as follows:Firstly,the spectrum characteristics of digital moire phase-shifting interferometry is studied.By studying on the spectrum characteristics of the digital moire phase-shifting interferometry,the range of the space carrier,the selection of filter parameters and the dynamic range of the digital moire phase-shifting interferometry are given.Secondly,the regularization phase tracking method used in digital Moire method is studied.Combining the regularization phase tracing method with the digital Moire method,the regularization mathematical model of the digital Moire synthesis graph is given,the energy function satisfying the continuity priori hypothesis is constructed,and the phase estimation algorithm based on the gradient descent function is designed and implemented.The theoretical feasibility of the regularization phase-tracing method is verified by simulation.Thirdly,Phase extraction method based on wavelet denoising is studied.An improved method of digital moire phase-shifting interferometry based on wavelet denoising is proposed.The process of phase extraction method based on wavelet denoising is introduced.The key steps of the wavelet denoising method are described,including the decomposition of the signal,the determination of the processing area and the selection of the threshold value.The dynamic range of wavelet denoising method is analyzed.The theoretical feasibility of Phase extraction method based on wavelet denoising is verified by simulation.At last,the feasibility of the regularization phase tracking method and the wavelet denoising method is verified by the design and conduct experiment.The measurement experiment of defocus spherical lens is designed,and the data processing process and result of regularization phase tracing method and wavelet denoising method are given.When applied to the actual interferograms,the error of the regularized phase tracking algorithm is greatly affected by noise.The wavelet denoising algorithm has high precision when applied to the actual interferometric.And the phase solution precision PV value is better than the1 14 λ,the RMS value is better than 1 100 λ,and the repeatability precision PV value is better than the 1 30 λ,the RMS value is better than 1 170 λ.In this thesis,the regularized phase tracking method and the phase extraction method based on the wavelet denoising are studied.The phase extraction mehod based on wavelet denoising can effectively extend the dynamic range of digital moire phase-shifting interferometry and the compensation range of partial compensator.This method helps to achieve a versatile on-line aspherical measurement in practical application.