Fringe-pattern demodulation using an iterative linear digital phase locked loop algorithm

Gdeisat, Munther; Burton, David R.; Lalor, Michael J.

doi:10.1016/j.optlaseng.2004.08.006

Cited by 6 publications

(4 citation statements)

References 10 publications

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“…However, the measurement structure for the surface shape of a microlens was incompatible with the measurement structure of the light characteristics of a microlens, and had to be measured by two instruments. Gdeisata et al (2005) proposed a novel technique termed an iterative linear digital phase locked loop (DPLL) for fringe-pattern demodulation. Huang et al (1999) proposed a novel digital fringe projection (DFP) technique for quantitative evaluation of corrosion.…”

Section: Introductionmentioning

confidence: 99%

An automatic optical inspection system for measuring a microlens array with an optical interferometric microscope and genetic algorithm

Yang

Lin

et al. 2013

Assembly Automation

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Purpose-The purpose of this paper is to propose an automatic optical inspection system for measuring the surface profile of a microlens array. Design/methodology/approach-The system setup was constructed according to the principle of the Fizeau interferometer. After capturing the ring interference fringe images of the microlens with a camera, the diameter, profile information and optical properties were analyzed through a microlens surface profile algorithm using innovative image pre-processing with a precision of less than 0.09 micron. Findings-By integrating with the genetic algorithm, the XY-Table shortest moving path of the system is calculated to achieve the purpose of highspeed inspection and automatic microlens array surface profile measurement. Originality/value-The measurement results of this system were also compared with other systems, including the atomic force microscope and stylus profiler, to verify the measurement precision and accuracy of this system.

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Section: Introductionmentioning

confidence: 99%

An automatic optical inspection system for measuring a microlens array with an optical interferometric microscope and genetic algorithm

Yang

Lin

et al. 2013

Assembly Automation

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“…Quan et al [16] proposed the 3D shape measurement of a hydroformed shell by a non-contact optical method based on the fringe projection technique. Munther et al [17] proposed a novel technique termed an iterative linear digital phase locked loop (DPLL) for fringe-pattern demodulation. This novel technique has better noise immunity than the basic 1D DPLL algorithms because it processes a fringe pattern in two dimensions.…”

Section: Introductionmentioning

confidence: 99%

An automatic evaluation method for the surface profile of a microlens array using an optical interferometric microscope

Lin

Loh

et al. 2010

Meas. Sci. Technol.

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In this paper, an automatic evaluation method for the surface profile of a microlens array using an optical interferometric microscope is presented. For inspecting the microlens array, an XY-table is used to position it. With a He–Ne laser beam and optical fiber as a probing light, the measured image is sent to the computer to analyze the surface profile. By binary image slicing and area recognition, this study located the center of each ring and determined the substrate of the microlens array image through the background of the entire microlens array interference image. The maximum and minimum values of every segment brightness curve were determined corresponding to the change in the segment phase angle from 0° to 180°. According to the ratio of the actual ring area and the ideal ring area, the area ratio method was adopted to find the phase-angle variation of the interference ring. Based on the ratio of actual ring brightness and the ideal ring brightness, the brightness ratio method was used to determine the phase-angle variation of the interference ring fringe. The area ratio method and brightness ratio method are interchangeable in precisely determining the phase angles of the innermost and outermost rings of the interference fringe and obtaining different microlens surface altitudes of respective pixels in the segment, to greatly increase the microlens array surface profile inspection accuracy and quality.

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“…Many techniques have been proposed for the analysis of fringe patterns such as: Fourier Fringe Analysis (FFA) [1][2][3][4][5][6][7][8][9][10], three-dimensional windowed Fourier Fringe Analysis [11], phase stepping [12][13][14][15][16], direct phase detection [17], wavelet transform fringe analysis [18][19][20][21][22], phase locked loop methods [23,24] and many other techniques. These methods all vary in accuracy, the number of frames required and processing time.…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional Fourier Fringe Analysis

Abdul-Rahman

Gdeisat

Burton

et al. 2008

Optics and Lasers in Engineering

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Fringe-pattern demodulation using an iterative linear digital phase locked loop algorithm

Cited by 6 publications

References 10 publications

An automatic optical inspection system for measuring a microlens array with an optical interferometric microscope and genetic algorithm

An automatic optical inspection system for measuring a microlens array with an optical interferometric microscope and genetic algorithm

An automatic evaluation method for the surface profile of a microlens array using an optical interferometric microscope

Three-dimensional Fourier Fringe Analysis

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