Study On The Key Technologies Of The Stitching Interferometry Of Cylindrical Surface

Cylindrical parts such as precision shafting play an important role in aerospace,numerical control machine,precision instruments and other engineering fields.Besides,there is a high requirement for the accuracy and quality of cylindrical optical elements in large-scale optical structures such as synchrotron radiation devices,high-power laser systems,satellite guidance and navigation systems.Due to the low axial sampling rate,the traditional contact measurement method is difficult to frequency-division reflect the shape error of the measured cylindrical surface.Compared with the contact measurement method,the area array measurement technology based on interferometry can achieve non-contact,high-precision and high-resolution cylindricity measurement,which has been proved to be an effective measurement method for cylindrical measurement.Therefore,this dissertation studies cylindrical surface measurement based on stitching interferometry,taking the misalignment error suppression of the cylindrical interferometry,adaptive strategy cylinder adjustment,evaluation of the cylindricity,cylindrical and acylindrical lens measurement as the perspective,providing the highprecision surface measurement and rich error characterization for cylindrical parts.The main research work is summarized as the following aspects:(1)Misalignment error suppression of cylindrical interferometry:In order to remove the misaligned aberration caused by the spatial position error of the measured cylinder,the misaligned aberration separation algorithm is deduced to effectively separate the real surface and misaligned aberration.The residual error of the sepereted surface is 5% of the real surface.(2)Strategy of adaptive cylinder adjustment:According to the requirements of high-precision cylinder measurement,a set of noncontact cylindricity adjustment device and an adaptive adjustment strategy is established.By analyzing and compensating the spatial attitude error of the cylinder,the adaptive leveling and centering function,automatic sampling and measuring are realized.The device can realize the leveling and centering of the cylinder in several minutes.After the fine adjustment,the horizontal error of the measured cylinder relative to the turntable is±10μm,the deflection error is ±0.2μrad.The proposed adjustment strategy greatly improves the robustness of the stitching interferometry and ensures the reliability of the stitching result.(3)Evaluation of the cylindricity based on the stitching interferoemetry:In order to enhance the ability of error representation of cylindricity error,this paper deepens the evaluation analysis of cylindrical error based on CGH reconstruction,and constructs the evaluation parameters from the aspects of power spectral density,separation of medium and low frequency errors,uncertainty estimation.The power spectral density of cylindrical profile error is analyzed to obtain the spatial frequency characteristic distribution of generatrix and circumferential direction.The twodimensional Gaussian filter weighting function for cylindrical contour is designed to separate and extract the low-frequency contour and medium-frequency waviness information of the cylindrical contour.Aiming at the lack of uncertainty of stitching results,the stitching interferometry model is analyzed,and the uncertainty of each point on the cylindrical surface is calculated.In addition,an uncertainty evaluation method of cylindricity of cylindrical stitching interferometry based on Bayesian estimation is proposed.The environmental error is introduced into the prior information of the subaperture.The global optimal subaperture joint probability distribution function is constructed.At the same time,the uncertainty interval of cylindricity is calculated by the Markov chain Monte Carlo method,which enhances the reliability of cylindricity of stitching results.(4)The measurement of cylindrical and acylindrical lenses:To solve the problem that the off-axis subapertures of cylindrical and acylindrical lens are lack of constraints,an iterative stitching interferometry of cylindrical surface is proposed.In the calculation process,the spatial position of subapertures is adjusted several times until the surface profile of cylindrical lens with high accuracy and no stitching trace is obtained.The residual of subapertures in overlapping areas is greatly suppressed.Aiming at the problem of high-gradient deviation of subaperture of acylindrical surface,an acylindrical stitching measurement method of CGH is proposed based on the existing measurement system.The linear relationship between different yawing angles of CGH and the generated coma wavefront is verified.The wavefront with specific coma aberration is generated by adjusting CGH,the surface deviation of the offaxis subaperture is compensated.The resolvable fringe pattern and phase are obtained and the phase reconstruction of the off-axis subaperture is realized.The phase reconstruction of the high steepness surface of the acylindrical lens surface is realized by the iterative stitching method.The measured results are consistent with the profilometer.The above research work provides a theoretical and technical basis for the conduction of cylindrical stitching interferometry,and realizes the measurement of ceramic plug gauge,metal shaft,glass cylinder,cylindrical and acylindrical lens.The method proposed in this paper has the characteristics of non-contact and high resolution.Compared with the results displayed by the current contact method,it has higher generatrix resolution and richer error characterization,more intuitively reflects the surface error of cylindrical parts,and establishes the foundation for the development of the new type of high-precision cylindricity measuring instrument.