A simple technique for measuring thickness distribution of transparent plates from a single image by using the sampling moiré method

Ri, Shien; Muramatsu, Takashi

doi:10.1088/0957-0233/21/2/025305

Cited by 22 publications

(10 citation statements)

References 16 publications

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“…By phase shifting spatially, i.e., changing the start-sampling pixel point in succession such that the sampling interval is similar to the pitch of the specimen grating, a series of moiré patterns can be attained. Eventually, from the series of phase-shifted moiré patterns, the phase of the moiré fringe is analyzed by using the phase-shifting method [2,3,[13][14][15].…”

Section: Principle Of Sampling Moiré Methodsmentioning

confidence: 99%

“…This method uses a charge-coupled device (CCD) or complementary metal-oxide semiconductor (CMOS) sensor to capture a single image of a specimen grating of known pitch during deformation. Only one image is handled to evaluate the phase distribution by generating multiple phase-shifted moiré patterns by the thinning-out, down-sampling, and interpolation of the sequential pixels through phase analysis [2][3][4][5][6][7][8][9][10][11][12][13][14][15]. Through the phase difference of the moiré fringe prior to deformation to that of post-deformation, the displacement distribution is attained.…”

Section: Introductionmentioning

confidence: 99%

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CCTV Camera Array for the Displacement and Strain Measurement of a Beam Specimen in a Laboratory

2022

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The available conventional sensors, like displacement transducers, used in the Structural Engineering Laboratory are expensive. In addition to that, the need for data acquisition devices also escalates the expense invested in point contact measurement systems. The recent appeal of vision-based measurement and the search for cost-effectiveness has led to an exploration of the established sampling moiré method using cheap closed-circuit television (CCTV) cameras as a viable option. The sampling moiré method is simple and analyzes the displacements from grating images by a phase-shifting method. Several trial experiments were conducted, which demonstrated that the setup is at least as accurate as the traditional measuring system. An experiment was conducted on a steel I-beam for displacement measurement, which displayed satisfactory results. In addition, the setup was also tested for strain measurement, and it has yielded promising results that need fine-tuning. This paper discusses the challenges, findings, and the possibility of incorporating vision-based displacement measurements in laboratory platforms.

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Section: Principle Of Sampling Moiré Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

CCTV Camera Array for the Displacement and Strain Measurement of a Beam Specimen in a Laboratory

2022

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“…However, the moiré technique is a typical method for quality control. It is a nondestructive technique used for measuring the thickness distribution of transparent plates [35].…”

Section: Introductionmentioning

confidence: 99%

Precision inspection of transparent component quality

Meziane

Saïd

Messagier

2023

Int J Adv Manuf Technol

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In this work, a method using transmission interferometry is proposed to detect surface defects on transparent materials. This technique is non-destructive and non-contact for the analysis of transparent and optical components whose surfaces vary from a few mm 2 to larger sizes. The purpose of this method is to provide, a means as simple as possible to identify defects with low contrast, and in particular barely visible defects, and of differentiate between the defects. The constructed transmission system generates fringes by the superposition of two microscopic periodic structures. According to the method, the test structure deforms after passing through the object. The information about surface defects is obtained from the object analyzed, and superposed on reference structure similar to test structure. Then, fringes are collected with information transported in the variation of their form. It is possible to clearly identify microscopic and submicroscopic defects thanks to the implementation of high-resolution detection in the nanoscale. The magnifying properties of the technique, up to 1000 times, allow better observation of defects which facilitates the automation of measurements and controls.Therefore, the proposed method can be suitable for the detection of surface defects in transparent optical objects such as optical lms, lenses, prisms.

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“…Mechanical stylus profilers [7] can measure thickness accurately, but the stylus may destroy the surface during tests; Ri and Muramatsu [8] realized non-contact thickness distribution measurements of transparent plates by using the sampling moiré method with an error ranging from 0.6% to 2.9% over a thickness of 3.5 mm, but the method is only applicable to isotropic materials with limited precision.…”

Section: Introductionmentioning

confidence: 99%

KTP crystal thickness distribution measurements based on laser feedback interferometry

Niu

Liu

et al. 2014

Appl. Opt.

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KTiOPO(4) (KTP) crystal is a widely used nonlinear optical crystal, and it can meet high requirements for parallelism of crystal surfaces and the length in the light propagation direction in its application fields. In this paper, we present a method for measuring the thickness distribution of cuboid KTP crystals based on laser feedback interferometry (LFI). The accuracy of the measurements for the relative thickness distribution was 8.8 nm, and that of the absolute thickness can be improved by increasing the accuracy of the refractive index. This method is applicable to measurements of all light transmissive birefringent materials, and the results provide detailed instructions for crystal processing and polishing.

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A simple technique for measuring thickness distribution of transparent plates from a single image by using the sampling moiré method

Cited by 22 publications

References 16 publications

CCTV Camera Array for the Displacement and Strain Measurement of a Beam Specimen in a Laboratory

CCTV Camera Array for the Displacement and Strain Measurement of a Beam Specimen in a Laboratory

Precision inspection of transparent component quality

KTP crystal thickness distribution measurements based on laser feedback interferometry

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