Aspheric subaperture stitching based on system modeling

Zhang, Lei; Liu, Dong; Shi, Tu; Yang, Yongying; Chong, Shiyao; Ge, Baoliang; Shen, Yibing; Bai, Jian

doi:10.1364/oe.23.019176

Cited by 32 publications

(13 citation statements)

References 20 publications

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“…2, a synthetic large sinusoidal surface was considered as the targeted measuring surface. The design of the surface is determined by (0, 0.1) 500 sin( ) cos( ) z GN xy    (9) where (0,0.1) GN is the added Gaussian noise with zero mean and 0.1 µm variance.…”

Section: Simulation Verificationmentioning

confidence: 99%

“…Moreover, they developed a coarse-to-fine stitching strategy. Zhang et al [9] developed a simultaneous reverse optimizing reconstruction method which is based on system modelling technique for aspheric sub-aperture stitching interferometer. Ye et al [10] used an optimal stitching planning method to measure large aspheric optical surface with ±4 mm range of probe and 20% of overlapped region.…”

Section: Introductionmentioning

confidence: 99%

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A Gaussian process and image registration based stitching method for high dynamic range measurement of precision surfaces

Liu

Cheung

Cheng

et al. 2017

Precision Engineering

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Please cite this article as: Liu MY, Cheung CF, Cheng CH, Su R, Leach R.K.A Gaussian process and image registration based stitching method for high dynamic range measurement of precision surfaces.Precision Engineering http://dx.doi.org/10. 1016/j.precisioneng.2017.04.017 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. 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. A Gaussian Highlights： It makes use of Gaussian process to model the sub-aperture measurement datasets to obtain the mean surface for registration, which is a novel method as comparing to traditional filtering methods, and provides better registration accuracy. Image registration and z shift method are used to simplify the 6 degrees of freedom 3D point cloud registration to a 3 degrees of freedom registration. Edge intensity data fusion method is used to fuse the overlapped region to provide a better transition between two datasets. It provides a novel stitching solution for a wide range of optical measurement instruments for achieving high dynamic range optical measurement of precision surfaces Abstract: Optical instruments are widely used for precision surface measurement. However, the dynamic range of optical instruments, in terms of measurement area and resolution, is limited by the characteristics of the imaging and the detection systems. If a large area with a high resolution is required, multiple measurements need to be conducted and the resulting datasets needs to be stitched together. Traditional stitching methods use six degrees of freedom for the registration of the overlapped regions, which can result in high computational complexity. Moreover, measurement error increases with increasing measurement data. In this paper, a stitching method, based on a Gaussian process, image registration and edge intensity data fusion, is presented. Firstly, the stitched datasets are modelled by using a Gaussian process so as to determine the mean of each stitched tile. Secondly, the datasets are projected to a base plane. In this way, the three-dimensional datasets are transformed to two-dimensional (2D) images. The images are registered by using an (x, y) translation to simplify the complexity. By using a high precision linear stage that is integral to the measurement instrument, the rotational error becomes insignificant and the cumulative rotational error can be eliminated. The translational error can be compensated by the image registration process. The z direction registration is performed by a least-squares error algorithm and the (x, y, z) translational information is determined. Finally, the overlapped regions of the measurement datasets are fused together by the edge intensity ...

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Section: Simulation Verificationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Gaussian process and image registration based stitching method for high dynamic range measurement of precision surfaces

Liu

Cheung

Cheng

et al. 2017

Precision Engineering

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“…Gappinger et al [ 33 ] modeled a non-null interferometric system and used the reverse iterative optimizing reconstruction (ROR) algorithm to calibrate the non-null interferometric results for the first time. Zhang et al [ 34 , 35 ] proposed a simultaneous reverse iterative optimizing reconstruction (SROR) algorithm for subaperture stitching, modeled the optical wedge scan interferometric system [ 36 ], and analyzed the influence of interferogram noise and modeling error on test accuracy. To address the influence of retrace error and alignment error in practical interferometers, a virtual–real combination interferometer was proposed in our previous work [ 37 , 38 ] as a tool to describe optical systems and eliminate system errors accurately.…”

Section: Introductionmentioning

confidence: 99%

Circular Subaperture Stitching Interferometry Based on Polarization Grating and Virtual–Real Combination Interferometer

Wang

Hao

2022

Sensors

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This paper presents a polarization grating based circular subaperture stitching interferometer. The system can be used for small F/# concave surface tests with a large F/# transmission sphere, where F/# is the ratio of focal length to aperture. A polarization grating was employed to deflect the incident beam for subaperture scanning by its axial rotation instead of a multi-axis motion-control system. Compared with the traditional subaperture stitching interferometric system, the system proposed in this paper is smaller in size and reduces the measurement error introduced by mechanical adjustment. Using a virtual interferometer model and a virtual–real combination algorithm to remove the retrace error, the full-aperture figure error can be directly obtained without the need for a complex stitching algorithm. The feasibility of the algorithm was verified, and the measurement error caused by the modeling error was analyzed by simulation. The capability of the polarization grating to scan subapertures was experimentally confirmed, and possible solutions to some engineering challenges were pointed out. The research in this paper has pioneering and guiding significance for the application of polarization grating in interferometry.

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“…Most methods typically require measuring sub-apertures of the unit, which are then 'stitched' together. Great improvements have been made in interferometry algorithms which lead to improved sub-aperture stitching results [14,[16][17][18]. Unfortunately, having an interferometric setup and the required null optic is not always a viable option.…”

Section: Introductionmentioning

confidence: 99%

Infinite deflectometry enabling 2π-steradian measurement range

Graves¹,

Quach²,

Choi³

et al. 2019

Opt. Express

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We present a novel deflectometry implementation termed Infinite Deflectometry. The technique provides a full aperture surface reconstruction sag map of freeform surfaces, including previously challenging to measure optics such as highly convex surfaces. The method relies on the creation of a virtual source enclosure around the tested optic, which creates a virtual 2π-steradian measurement range. To demonstrate the performance, a fast f/1.26 convex optical surface was measured with a commercial interferometer and with the Infinite Deflectometry system. After removing Zernike terms 1 through 37, the metrology tests resulted in absolute RMS surface values of 18.48 nm and 16.26 nm, respectively. Additionally, a freeform Alvarez lens was measured with the new technique and measured 22.34 m of surface sag RMS after piston, tip/tilt, and defocus had been removed. The result deviated by 488 nm RMS from a profilometer measurement while standard interferometry failed to measure the Alvarez lens due to its non-nulled wavefront dynamic range limitation.

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Aspheric subaperture stitching based on system modeling

Cited by 32 publications

References 20 publications

A Gaussian process and image registration based stitching method for high dynamic range measurement of precision surfaces

A Gaussian process and image registration based stitching method for high dynamic range measurement of precision surfaces

Circular Subaperture Stitching Interferometry Based on Polarization Grating and Virtual–Real Combination Interferometer

Infinite deflectometry enabling 2π-steradian measurement range

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