• Korean Journal of Optics and Photonics
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• v.14 no.4
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• pp.392-398
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• 2003

We present a novel concept of a phase-shifting diffraction-grating interferometer, which is intended for the optical testing of concave mirrors with high precision. The interferometer is configured with a single reflective diffraction grating, which performs multiple functions of beam splitting, beam recombination, and phase shifting. The reference and test wave fronts are generated by means of reflective diffraction at the focal plane of a microscope objective with large numerical aperture, which allows testing fast mirrors with low f-numbers. The fiber-optic confocal design is adopted for the microscope objective to focus a converging beam on the diffractive grating, which greatly reduces the alignment error between the focusing optics and the diffraction grating. Translating the grating provides phase shifting, which allows measurement of the figure errors of the test mirror to nanometer accuracy.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.47 no.2
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• pp.51-60
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• 2010

This paper proposes a new scheme to obtain enhanced 3D shape information rapidly for WLPSI(White Light Phase Shifting Interferometry). WLPSI is a convenient method to measure the height of the micro products. First we propose an effective method of limiting search interval for detecting the peak of the visibility function in order to obtain 3D shpae information rapidly. Second we propose an automatic base level decision method basad on image processing and a correction algorithm using the least square approximation method to overcome the global tilt problem of the conventional WLPSI algorithms. Third we propose an adaptive filtering method to remove the distortion known as bat-wing effect which appears near the step discontinuity. Experimental results show that the proposed overall technique is fast and provides more enhanced 3D shape information compared with the conventional WLPSI algorithms.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.629-630
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• 2012

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.1079-1080
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• 2013

• Proceedings of the Optical Society of Korea Conference
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• 2003.07a
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• pp.148-149
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• 2003

렌즈와 거울의 형상을 정밀하게 측정하고 평가하는 광학시험에 많은 형태의 광간섭계가 개발되고 사용되어왔다. 그 중, 회절격자를 광선분할기로 사용하는 광간섭계들을 통칭하여 회절격자 간섭계라 부른다. 회절격자 간섭계는 별개의 광학표면을 사용하지 않고 회절격자에서 회절된 파면을 직접 기준파면으로 사용할 수 있으므로, 격자의 형태, 주기를 선정하여 기준파면과 측정파면을 원하는 방향으로 재생하여 다양한 형태의 간섭계를 만들 수 있다.(중략)

• Proceedings of the Optical Society of Korea Conference
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• 2003.07a
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• pp.274-275
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• 2003

광통신 분야의 연구 중 근거리 광통신 분야에 적용하기 위한 Plastic Optical Fiber(POF)에 관한 연구와 개발이 활발히 이루어지고 있다. POF의 광전송 특성을 결정짓는 요소 중 가장 중요한 특성이 바로 굴절률 분포이다. 이에 따라 그동안 다양한 형태의 POF 굴절률 측정 방법이 연구되어 왔다. 기존 Glass Optical Fiber의 굴절률 분포 측정 방법 중 가장 일반적이고 효과적인 방법 중 하나는 coherent 빛의 간섭을 이용한 transverse interferograms을 분석하는 방법으로 Fizeau 간섭계와 같은 간섭계를 이용하여 위상변화를 측정하고 측정한 위상을 tomography적인 해석방법을 통해 굴절률 분포를 계산하는 방법이다. (중략)

• Korean Journal of Optics and Photonics
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• v.15 no.3
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• pp.248-253
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• 2004

We propose a near- field scanning optical interferometer (NSOI) based on the facet reflection of a nano-sized moveable tapered optical fiber. The interferometer can measure the position and the wave-front of a focused spot simultaneously. The interfering fringes are generated by the reflected beams from the sample surface and from the fiber facet. The wave-front analysis at the focusing position is obtained by using a phase shifting technique with a four-step algorithm. It is found that the resolution for controlling the focal position of our proposed NSOI is less than λ/3 and the measured wave-front aberration at the focal position is in good agreement with the ones obtained by a Twyman-Green interferometer.

• Proceedings of the Optical Society of Korea Conference
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• 2005.07a
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• pp.246-247
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• 2005

• Proceedings of the Optical Society of Korea Conference
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• 2004.02a
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• pp.32-33
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• 2004

• Journal of IKEEE
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• v.28 no.3
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• pp.271-278
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• 2024

An encryption and decryption method using phase mapping of a gray scale image based on a phase-shifting interferometry principle is proposed in which an encrypted image is formed into complex digital hologram function by symmetric security key in the proposed encryption system.. The gray scale image to be encrypted is converted to phase mapped function that is mixed with a randomly generated binary security encryption key and is used as an input. Decryption of phase information is performed by complex digital hologram and security encryption key, which reconstructs the original gray scale image by phase unmapping. The proposed method confirms that correlation coefficient of the decrypted image is 0.995 when quantization level of CCD is 8-bits(2⁸=256 levels).