• Korean Journal of Optics and Photonics
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• v.24 no.6
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• pp.318-323
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• 2013

Digital holographic microscopy allows optical path difference measurement. Optical path difference depends on both the refractive index and the morphology of the sample. When interference fringes are very closely spaced, the phase data contain high frequencies where $2{\pi}$ ambiguities cannot be resolved. The immersion testing method, which is a transmission test while the sample is immersed in liquid, is very effective in reducing high frequency fringes in transmission measurements so that large dynamic range testing is possible for a non-null configuration. We developed a digital holographic microscope using liquid that can measure the high numerical aperture aspheric morphology of a sample. This system provides highly precise three-dimensional information on the sample. By improving the experimental method, choosing liquids which have similar refractive index to the sample, we can measure more accurate three-dimensional information on the samples.

• Proceedings of the Optical Society of Korea Conference
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• 2009.10a
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• pp.329-330
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• 2009

• Proceedings of the Optical Society of Korea Conference
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• 2007.07a
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• pp.69-70
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• 2007

• Proceedings of the Optical Society of Korea Conference
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• 2008.07a
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• pp.173-174
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• 2008

• Korean Journal of Optics and Photonics
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• v.17 no.4
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• pp.329-334
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• 2006

We have reconstructed 3-dimensional images by using the digital holographic microscope and the Mask-cut phase unwrapping algorithm. Off-axis holograms recorded with a magnified image of the microscopic object lens and reference beam are numerically reconstructed in amplitude and phase image by the Fresnel diffraction approximation. We have simultaneously reconstructed 2-dimensional and 3-dimensional images of the sub-micrometer objects.

• Korean Journal of Optics and Photonics
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• v.22 no.5
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• pp.214-218
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• 2011

In this paper we have applied self-reference hologram to DHM (digital holography microscopy) to remove phase aberration. We have constructed an off-axis reflection- type digital holography microscope. We have extracted a low spatial frequency hologram from the conjugated hologram and used it as a reference hologram. Experimentally we show that distortion of image and aberration of phase in a measurement system are removed using the self-reference hologram.

• Korean Journal of Optics and Photonics
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• v.17 no.4
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• pp.323-328
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• 2006

A fundamental problem in digital holography is the presence of zero-order noise in the reconstruction process, which decreases the signal to noise ratio(SNR). For many applications, that reduction of SNR makes digital holography impractical, so a great number of approaches have been tested in order to overcome such a problem. In this paper we use the scanning method to suppress the zero-order diffraction noise and the interference noise between object beams. We demonstrate that it is possible to increase the image quality with the scanning method.

• Korean Journal of Optics and Photonics
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• v.21 no.3
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• pp.91-96
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• 2010

The size of a reconstructed image depends on the reconstruction distance and wavelength. The double fourier transform method is proposed to eliminate the dependence on the reconstruction distance and wavelength. We can get a fixed reconstructed image size by using the double fourier transform method. Two wavelength digital holography is proposed to measure the step height, which is larger than a single wavelength. The two image size of different wavelength holograms should be the same in order to apply two wavelength digital holography. We use two wavelength digital holography and double fourier transforms to measure the step height. The measured data were reasonable and we found that the double fourier transform is useful in two wavelength digital holography.

• Journal of Broadcast Engineering
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• v.28 no.1
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• pp.55-78
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• 2023

The fringe pattern obtained through a DHM (Digital Holographic Microscopy) contains the thickness information of the sample. However, there is a disadvantage that the data capacity is large. Therefore, a compression method that can reduce the data size while minimizing damage to the thickness information of the sample contained in the fringe pattern is required. This paper presents the phase compression method and confirmed through experiments that the phase compression method is more efficient that the fringe pattern compression method used in JPEG Pleno Holography. As a result of evaluation using RMSE, BD-Rate and PSNR the phase compression method showed up to 92.39% improvement in performance than the fringe pattern compression method. In addition, experiment were conducted under various conditions to compare and analyze the compression performance for each condition. In the case of the fringe pattern compression method, it includes not only the phase information for calculating the thickness of the sample but also other information, whereas the phase compression method compresses only the phase information after removing unnecessary information from the fringe pattern. It is judged to have high performance.