Ruiyang Wang - Academia.edu (original) (raw)

Papers by Ruiyang Wang

Research paper thumbnail of Study on eliminating the effect of parasitic reflection on deflectometry measurement of planar optical element surface figure

9th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Meta-Surface-Wave and Planar Optics

Phase measuring deflectometry (PMD) with structured light projection and phase-shifting technique... more Phase measuring deflectometry (PMD) with structured light projection and phase-shifting technique is a highly accurate optical surface measuring method. For surface shape measurement of transparent planar elements, PMD suffers from parasitic reflection. To avoid the unwanted effect of parasitic reflection, a method based on fringe frequency tuning and Fourier-transform is introduced in this paper. Numerical simulations and experiments are both conducted to evaluate the performance of the proposed method. An optical planar element with a thickness of 24.5mm is measured, and measurement error is within 200nm PV.

Research paper thumbnail of Marker-free stitching deflectometry for three-dimensional measurement of the specular surface

Optics Express, 2021

Due to the ‘invisible’ property of the specular surface, it is difficult for the stitching deflec... more Due to the ‘invisible’ property of the specular surface, it is difficult for the stitching deflectometry to identify the overlapping area. Previously, markers were used on the unit under test with a roughly known shape to find the overlapping area. We propose a marker-free stitching deflectometry that utilizes the stereo-iterative algorithm to calculate the sub-aperture point cloud without height-slope ambiguity, and the overlapping area is identified with the point cloud datum. The measured area is significantly enlarged. The simulation and experiments are conducted to verify the proposal and evaluate the accuracy. We test a high-quality flat with 190mm diameter, the measurement error is below 100nm RMS with comparison to the interferometer.

Research paper thumbnail of Transparent element surface measurement using binary pattern in phase-measuring deflectometry

Advances in Metrology for X-Ray and EUV Optics VIII, 2019

For on-line surface measurement of transparent optical elements, phase measuring deflectometry (P... more For on-line surface measurement of transparent optical elements, phase measuring deflectometry (PMD) is a very promising method. However, the parasitic reflection from the rear surface is an existing problem for PMD to measure transparent element. A parasitic reflection eliminating method using binary pattern is proposed, the principle of which is described in detail. And the proposed method is implemented on a transparent window glass with a thickness of about 10mm. The surface shape result shows a good agreement with the interferometer data with a sub-wavelength level accuracy.

Research paper thumbnail of Polarization aberrations corrections and polarization-dependent imaging quality analysis in polarization lidars

Optics Communications, 2021

Abstract The polarization aberration in lidar system can reduce the imaging quality and causes th... more Abstract The polarization aberration in lidar system can reduce the imaging quality and causes the atmospheric polarization measurement error. In order to accurate polarization signal measurement, the polarization aberration correction of system is necessary. In this paper, the physical properties of Jones pupil function are analyzed and the polarization-dependent point spread function is derived for the polarization lidar. A high-reflection dielectric multilayer coating with low polarization effect is designed to correct the polarization aberration of Cassegrain telescope in lidar. The simulation shows that the polarization aberration of telescope coated with multilayer coatings are significantly smaller than that coated with aluminum coating. Furthermore, the imaging quality performance of telescope coated with multilayer coatings is analyzed, and the relative error of atmosphere parameter is calibrated based on the imaging information of two receiver channels in linear or circular polarization lidar. The correction method can reduce the polarization aberration and improve the measurement accuracy in polarization lidar.

Research paper thumbnail of Phase extraction based on iteration algorithm with crossed fringes in phase measuring deflectometry

In phase measuring deflectometry, two orthogonal sinusoidal fringe patterns are separately projec... more In phase measuring deflectometry, two orthogonal sinusoidal fringe patterns are separately projected on the test surface and the distorted fringes reflected by the surface are recorded, each with a sequential phase shift. Then the two components of the local surface gradients are obtained by triangulation. It usually involves some complicated and time-consuming procedures (fringe projection in the orthogonal directions, accurate phase shifting).To avoid the complex process, a novel phase extraction algorithm with crossed fringes is presented in this paper. It is based on a least-squares iterative process. Both a numerical simulation and a preliminary experiment are conducted to verify the validity and performance of this algorithm. Experimental results obtained by our method are shown, and comparisons between our experimental results and those obtained by the traditional phase-shifting algorithm and between our experimental results and those measured by the Fizeau interferometer are...

Research paper thumbnail of Comparison of Camera Calibration and Measurement Accuracy Techniques for Phase Measuring Deflectometry

Applied Sciences, 2021

Phase measuring deflectometry (PMD) is a competitive method for specular surface measurement that... more Phase measuring deflectometry (PMD) is a competitive method for specular surface measurement that offers the advantages of a high dynamic range, non-contact process, and full field measurement; furthermore, it can also achieve high accuracy. Camera calibration is a crucial step for PMD. As a result, a method based on the calibration of the entrance pupil center is introduced in this paper. Then, our proposed approach is compared with the most popular photogrammetric method based on Zhang’s technique (PM) and Huang’s modal phase measuring deflectometry (MPMD). The calibration procedures of these three methods are described, and the measurement errors introduced by the perturbations of degrees of freedom in the PMD system are analyzed using a ray tracing technique. In the experiment, a planar window glass and an optical planar element are separately measured, and the measurement results of the use of the three methods are compared. The experimental results for the optical planar eleme...

Research paper thumbnail of Dynamic speckle deflectometry based on backward digital image correlation

Measurement, 2021

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Research paper thumbnail of Phase extraction based on iterative algorithm using five-frame crossed fringes in phase measuring deflectometry

Optics and Lasers in Engineering, 2018

In phase measuring deflectometry, two orthogonal sinusoidal fringe patterns are separately projec... more In phase measuring deflectometry, two orthogonal sinusoidal fringe patterns are separately projected on the test surface and the distorted fringes reflected by the surface are recorded, each with a sequential phase shift. Then the two components of the local surface gradients are obtained by triangulation. It usually involves some complicated and time-consuming procedures (fringe projection in the orthogonal directions). In addition, the digital light devices (e.g. LCD screen and CCD camera) are not error free. There are quantization errors for each pixel of both LCD and CCD. Therefore, to avoid the complex process and improve the reliability of the phase distribution, a phase extraction algorithm with five-frame crossed fringes is presented in this paper. It is based on a least-squares iterative process. Using the proposed algorithm, phase distributions and phase shift amounts in two orthogonal directions can be simultaneously and successfully determined through an iterative procedure. Both a numerical simulation and a preliminary experiment are conducted to verify the validity and performance of this algorithm. Experimental results obtained by our method are shown, and comparisons between our experimental results and those obtained by the traditional 16-step phase-shifting algorithm and between our experimental results and those measured by the Fizeau interferometer are made.

Research paper thumbnail of Study on eliminating the effect of parasitic reflection on deflectometry measurement of planar optical element surface figure

9th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Meta-Surface-Wave and Planar Optics

Phase measuring deflectometry (PMD) with structured light projection and phase-shifting technique... more Phase measuring deflectometry (PMD) with structured light projection and phase-shifting technique is a highly accurate optical surface measuring method. For surface shape measurement of transparent planar elements, PMD suffers from parasitic reflection. To avoid the unwanted effect of parasitic reflection, a method based on fringe frequency tuning and Fourier-transform is introduced in this paper. Numerical simulations and experiments are both conducted to evaluate the performance of the proposed method. An optical planar element with a thickness of 24.5mm is measured, and measurement error is within 200nm PV.

Research paper thumbnail of Marker-free stitching deflectometry for three-dimensional measurement of the specular surface

Optics Express, 2021

Due to the ‘invisible’ property of the specular surface, it is difficult for the stitching deflec... more Due to the ‘invisible’ property of the specular surface, it is difficult for the stitching deflectometry to identify the overlapping area. Previously, markers were used on the unit under test with a roughly known shape to find the overlapping area. We propose a marker-free stitching deflectometry that utilizes the stereo-iterative algorithm to calculate the sub-aperture point cloud without height-slope ambiguity, and the overlapping area is identified with the point cloud datum. The measured area is significantly enlarged. The simulation and experiments are conducted to verify the proposal and evaluate the accuracy. We test a high-quality flat with 190mm diameter, the measurement error is below 100nm RMS with comparison to the interferometer.

Research paper thumbnail of Transparent element surface measurement using binary pattern in phase-measuring deflectometry

Advances in Metrology for X-Ray and EUV Optics VIII, 2019

For on-line surface measurement of transparent optical elements, phase measuring deflectometry (P... more For on-line surface measurement of transparent optical elements, phase measuring deflectometry (PMD) is a very promising method. However, the parasitic reflection from the rear surface is an existing problem for PMD to measure transparent element. A parasitic reflection eliminating method using binary pattern is proposed, the principle of which is described in detail. And the proposed method is implemented on a transparent window glass with a thickness of about 10mm. The surface shape result shows a good agreement with the interferometer data with a sub-wavelength level accuracy.

Research paper thumbnail of Polarization aberrations corrections and polarization-dependent imaging quality analysis in polarization lidars

Optics Communications, 2021

Abstract The polarization aberration in lidar system can reduce the imaging quality and causes th... more Abstract The polarization aberration in lidar system can reduce the imaging quality and causes the atmospheric polarization measurement error. In order to accurate polarization signal measurement, the polarization aberration correction of system is necessary. In this paper, the physical properties of Jones pupil function are analyzed and the polarization-dependent point spread function is derived for the polarization lidar. A high-reflection dielectric multilayer coating with low polarization effect is designed to correct the polarization aberration of Cassegrain telescope in lidar. The simulation shows that the polarization aberration of telescope coated with multilayer coatings are significantly smaller than that coated with aluminum coating. Furthermore, the imaging quality performance of telescope coated with multilayer coatings is analyzed, and the relative error of atmosphere parameter is calibrated based on the imaging information of two receiver channels in linear or circular polarization lidar. The correction method can reduce the polarization aberration and improve the measurement accuracy in polarization lidar.

Research paper thumbnail of Phase extraction based on iteration algorithm with crossed fringes in phase measuring deflectometry

In phase measuring deflectometry, two orthogonal sinusoidal fringe patterns are separately projec... more In phase measuring deflectometry, two orthogonal sinusoidal fringe patterns are separately projected on the test surface and the distorted fringes reflected by the surface are recorded, each with a sequential phase shift. Then the two components of the local surface gradients are obtained by triangulation. It usually involves some complicated and time-consuming procedures (fringe projection in the orthogonal directions, accurate phase shifting).To avoid the complex process, a novel phase extraction algorithm with crossed fringes is presented in this paper. It is based on a least-squares iterative process. Both a numerical simulation and a preliminary experiment are conducted to verify the validity and performance of this algorithm. Experimental results obtained by our method are shown, and comparisons between our experimental results and those obtained by the traditional phase-shifting algorithm and between our experimental results and those measured by the Fizeau interferometer are...

Research paper thumbnail of Comparison of Camera Calibration and Measurement Accuracy Techniques for Phase Measuring Deflectometry

Applied Sciences, 2021

Phase measuring deflectometry (PMD) is a competitive method for specular surface measurement that... more Phase measuring deflectometry (PMD) is a competitive method for specular surface measurement that offers the advantages of a high dynamic range, non-contact process, and full field measurement; furthermore, it can also achieve high accuracy. Camera calibration is a crucial step for PMD. As a result, a method based on the calibration of the entrance pupil center is introduced in this paper. Then, our proposed approach is compared with the most popular photogrammetric method based on Zhang’s technique (PM) and Huang’s modal phase measuring deflectometry (MPMD). The calibration procedures of these three methods are described, and the measurement errors introduced by the perturbations of degrees of freedom in the PMD system are analyzed using a ray tracing technique. In the experiment, a planar window glass and an optical planar element are separately measured, and the measurement results of the use of the three methods are compared. The experimental results for the optical planar eleme...

Research paper thumbnail of Dynamic speckle deflectometry based on backward digital image correlation

Measurement, 2021

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Research paper thumbnail of Phase extraction based on iterative algorithm using five-frame crossed fringes in phase measuring deflectometry

Optics and Lasers in Engineering, 2018

In phase measuring deflectometry, two orthogonal sinusoidal fringe patterns are separately projec... more In phase measuring deflectometry, two orthogonal sinusoidal fringe patterns are separately projected on the test surface and the distorted fringes reflected by the surface are recorded, each with a sequential phase shift. Then the two components of the local surface gradients are obtained by triangulation. It usually involves some complicated and time-consuming procedures (fringe projection in the orthogonal directions). In addition, the digital light devices (e.g. LCD screen and CCD camera) are not error free. There are quantization errors for each pixel of both LCD and CCD. Therefore, to avoid the complex process and improve the reliability of the phase distribution, a phase extraction algorithm with five-frame crossed fringes is presented in this paper. It is based on a least-squares iterative process. Using the proposed algorithm, phase distributions and phase shift amounts in two orthogonal directions can be simultaneously and successfully determined through an iterative procedure. Both a numerical simulation and a preliminary experiment are conducted to verify the validity and performance of this algorithm. Experimental results obtained by our method are shown, and comparisons between our experimental results and those obtained by the traditional 16-step phase-shifting algorithm and between our experimental results and those measured by the Fizeau interferometer are made.