• Korean Journal of Optics and Photonics
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• v.1 no.1
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• pp.12-15
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• 1990

Holospeckle interferometry, the combined technique of holographic interferometry and speckle photography, was applied to the measurement of 3-D contact deformation created by an indentor. This new tech$.$ nique makes possible to measure both in-plane and out-of-plane displacements from one photographic plate. In this study, the optical system based on image holography was set up. In order to enhance the size and the contrast of the speckle, a proper magnification and a low reference beam ratio was used as compared with the conventional holographic interferometry technique. This system shows the magnified and clear holographic interference fringe as well as Young's fringe patterns.tterns.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.6
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• pp.1485-1492
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• 2015

This paper proposes a double frequency method using FTP(Fourier Transform Profilometry) in fringe projection techniques for 3D measurement systems. In fringe projection techniques, fringe pattern images are projected and captured, and then object is measured by analysing phase. PMP(Phase Measuring Profilometry) for analysing phase provides high-resolution and is robust to object's reflection and background intensities. However, the measurement range is narrow due to 2π ambiguity. In order to overcome this problem, a double frequency method is often used. This method can widen the range of measurement while maintaining the high-resolution, but the measurement time is taken about twice due to grab 2 times number of images. The proposed double frequency method using FTP requires an additional image for resolving 2π ambiguity. The proposed method effectively reduces the measurement time while maintaining the same accuracy.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.389-392
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• 2016

As technologies evolve, 3D measurement techniques using cameras have been developed continuously. In 3D measurement, high accuracy, fast speed, and easy implementation are very important factors. Recently, 3D measurement using multi-frequency fringes has been widely used. This method is generally a method of measuring the height of a image obtained by projecting a sine wave through the projector. The sine wave is produced by software. However, this sine wave is not a perfect sine wave by gamma of projector. This is given a bad influence on the height measurement, and can not measure the correct height. In this paper, we propose a method for correcting the phase of the sine wave to avoid being affected gamma. Through this method it will be able to make more accurate height measurement.

• Journal of Advanced Marine Engineering and Technology
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• v.12 no.3
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• pp.43-56
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• 1988

The image processing system consisted of the microcomputer IBM PC-XT and the graphic board (16 gray level and $640{\times}400$ pixels resolution) has been proposed, and the image processing softwares programmed in the BASIC and in the assembler language have been developed. The programs are consisted of the main menu and the sub menu, that have contained the subroutine for the capture for image data, the determination of region, the histogram, the change of value, the montage, the skeleton, the mask, the moving, the zoom, the disk access and the print. For the application, the photoelastic fringe data have been captured and analyzed. It was seen that the programs are available for the image processing.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.163-163
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• 2009

Viewing angle controllable liquid crystal display (LCD) associated with fringe-field switching (FFS) mode with high image quality is proposed. In the device, one pixel is composed of main and sub pixels, in which adjacent sub pixel is patterned with pixel electrodes direction orthogonal to the adjacent one. In this way, light leakage can be generated in the all viewing angle directions except the normal direction, realizing view angle controllable LCD in both horizontal and vertical directions.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.2
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• pp.564-574
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• 1996

This paper describes as Electronic Speckle Pattern Interferometry system which has been designed for measuring vibration patterns and quantitative measurement of vibration amplitude fields by using the time average method on a object. Visbility of fringe patterns is more improved by using the phase stepping and frame average method to reduce speckle and electric noise. And a bias vibration is introduced into the reference beam to shift the $\frac{2}{0}$ fringes so that fringe shift algorithms can be used to determine vibration amplitude. The experimental results are compared to those of the FFT analyzer and the FEM model analysis.

• Journal of Mechanical Science and Technology
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• v.16 no.2
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• pp.175-181
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• 2002

A new polariscope system involving two rotating optical elements and a digital camera for whole field fringe analysis allows automated data to be acquired quickly and efficiently. The developed phase measuring technique that uses eight images through a circular polariscope is presented for the digital measurement of isochromatics and isoclinics, respectively, from photoelastic fringes in a circular disk under diametric compression. Isochromatics can directly be obtained using wrapped isoclinic phases calculated by the arc tangent operator which is the four-quadrant operator from -$\pi$ to $\pi$. It is not required to unwrap isoclinic phases for the calculations of isochromatics. Unwrapped isoclinics are directly determined from isochromatic parameters. Distributions of digitally determined isoclinics are in close agreement to manual measurements. The errors which would appear in unwrapping process of isoclinics can be avoided in the determination of isochromatics.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.686-689
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• 2003

Many technologies are applied to the measurement of elastohydrodynamic lubrication (EHL) film thickness. In particular, optical in-situ interferometric method has many advantages in making the actual contact behaviors realized with the experimental apparatus. Careful selection of incident lights greatly enhances the fringe resolution up to nanometer scale by using image processing technology. In this work, it is found that dichromatic incident light can provide much finer resolution of EHL film thickness than monochromatic incident light, because it has much more variables of color components to be discriminated among the wavelengths of colors according the variations of EHL film thickness. Some simulated interferometric images are shown how the film thickness is resolutionized in nanometer scale

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.419-422
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• 2005

We have studied transflective liquid crystal displays (LCDs) associated with fringe-field switching (FFS) mode to achieve high image quality. In the past, several cell structures were used to fabricate transflective FFS liquid crystal display s. Their structures and characteristics are carefully examined to find their merits and cons. Further, optimization of cell parameters to achieve a single driving circuit is performed.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.545-548
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• 2007

This Viewing angle control of fringe-field switching (FFS)-LCD using only one panel has been investigated. Viewing angle switching cell is composed of main- and sub-pixel, in which the former has a role of image expression and the latter has a role of viewing angle switching.