• Journal of Sensor Science and Technology
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• v.4 no.2
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• pp.22-28
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• 1995

A Michelson interferometric AC current sensor has been fabricated by using a single mode optical fiber and a cylindrical PZT tube of which a radial dimension varies with applied voltage. The signal processing scheme used in this work, measures the magnitude of AC current regardless of the frequency of the current. An AC current is measured by counting the number of interference fringe during half cycle of the AC current. The number of interference fringes varies linearly with the magnitude of the current and the error range is within 5% at the temperature range from $-20^{\circ}C$ to $80^{\circ}C$.

• Korean Journal of Optics and Photonics
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• v.16 no.3
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• pp.239-247
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• 2005

In this study, we have used newly developed dual-beam shearography which is based on laser speckle that includes various information about an object. Among the several shearing techniques, we used Michelson shearing interference technique which is the most powerful. Acrylate plate was used as a sample, which has inner defects and low thermal conductivity. Michelson shearing interferometer was used for obtaining speckle fringes. We also used phase shifting technique to get a phase map. Using single beam illumination, we could obtain mixture of deformation components of both in-plane and out-of-plane. In order to separate the two components, we have used dual-beam shearography technique. We have obtained a speckle pattern of both before and after deformation. Through LS filtering and unwrapping processes, we could find a position and a shape of the inner defects easily. Deformation of the acrylate plate due to thermal heating has occurred mainly in z-direction(out-of-plane) because it has low thermal conductivity. The acrylate plate was deformed only at the restricted area where the electrical heat applied.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.182-187
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• 2000

빛은 공간상에서 전파되는 특성상 전자기파(electromagnetic wave)로 규정될 수 있다. 빛의 파동성은 여러 형태의 간섭을 유발한다. 이중 정밀 길이측정에는 광위상간섭(phase measuring interferometry)의 원리가 대표적으로 이용된다. 그림1은 광위상간섭의 기본원리를 Michelson 광학계를 이용하여 설명하고 있다. 하나의 동일한 광원으로부터 출발된 광속(optical beam)은 광분할기(beam splitter)에 의해 두 개로 별도 광속으로 분활 된다. (중략)

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2707-2709
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• 2002

In this paper, we suggest new optical eye-diagnosis medical equipment. First, we simulate light propagation in bio-tissue using MC method. Second, we propose the OCT design parameter using Michelson interferometer.

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.216-217
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• 2003

컴퓨터 기술, 영상 처리기술, 기계장치의 자동화 발전에 따라 레이저를 이용한 형상 측정 기술 개발은 반도체 표면 측정 등에 응용되어지는 매우 중요한 분야를 차지하고 있다. 레이저를 이용한 정밀 표면 측정 기술은 레이저 파장의 1／4에 해당하는 높이까지 CCD 카메라와 연계시켜 측정할 수가 있다. 레이저 간섭계는 Michelson, Mirau, Linnik 등에 의해 개발된 간섭계가 주로 이용되고 있다. 본 논문에서는 4-bucket 알고리즘을 사용하기 위하여 영상을 $\theta$＝$\pi$／2씩 위상 이동시켜 다음과 같은 4개의 간섭 무의 강도 영상 정보를 획득하여 Borland C++ 프로그램을 이용 위상을 계산하였다. (중략)

• Proceedings of the KIEE Conference
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• 2002.11a
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• pp.239-241
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• 2002

Basically, OCT used the interference effect of Michelson interferometer. First, we have analyzed the optical heterodyne interferometer for OCT. Second, we implement new optical heterodyne interferometer for OCT.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.195.1-195.1
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• 2016

Currently, as Plasma application is expanded to the industrial and medical industrial, low temperature plasma applications became important. Especially in medical and biology, many researchers have studied about generated radical species in atmospheric pressure low temperature plasma directly adapted to human body. Therefore, so measurement their plasma parameter is very important work and is widely studied all around world. One of the plasma parameters is electron density and it is closely relative to radical production through the plasma source. some kinds of method to measuring the electron density are Thomson scattering spectroscopy and Millimeter-wave transmission measurement. But most methods have very expensive cost and complex configuration to composed of experiment system. We selected Michelson interferometer system which is very cheap and simple to setting up, so we tried to measuring electron density by laser interferometer with laser beam chopping module for measurement of temporal phase difference in plasma jet. To measuring electron density at atmospheric pressure Ar plasma jet, we obtained the temporal phase shift signal of interferometer. Phase difference of interferometer can occur because of change by refractive index of electron density in plasma jet. The electron density was able to estimate with this phase difference values by using physical formula about refractive index change of external electromagnetic wave in plasma. Our guiding laser used Helium-Neon laser of the centered wavelength of 632 nm. We installed chopper module which can make a 4kHz pulse laser signal at the laser front side. In this experiment, we obtained more exact synchronized phase difference between with and without plasma jet than reported data at last year. Especially, we found the phase difference between time range of discharge current. Electron density is changed from Townsend discharge's electron bombardment, so we observed the phase difference phenomenon and calculated the temporal electron density by using phase shift. In our result, we suggest that the electron density have approximately range between 1014~ 1015 cm-3 in atmospheric pressure Ar plasma jet.

• Journal of the Optical Society of Korea
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• v.20 no.1
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• pp.78-87
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• 2016

Red blood cells (RBCs) are customarily adhered to a bio-functionalised substrate to make them stationary in interferometric phase-imaging modalities. This can make them susceptible to receive alterations in innate morphology due to their own weight. Optical tweezers (OTs) often driven by Gaussian profile of a laser beam is an alternative modality to overcome contact-induced perturbation but at the same time a steeply focused laser beam might cause photo-damage. In order to address both the photo-damage and substrate adherence induced perturbations, we were motivated to stabilize the RBC in OTs by utilizing a laser beam of ‘arbitrary intensity profile’ generated by a source having cavity imperfections per se. Thus the immobilized RBC was investigated for phase-imaging with sinusoidal interferograms generated by a compact and robust Michelson interferometer which was designed from a cubic beam splitter having one surface coated with reflective material and another adjacent coplanar surface aligned against a mirror. Reflected interferograms from bilayers membrane of a trapped RBC were recorded and analyzed. Our phase-imaging set-up is limited to work in reflection configuration only because of the availability of an upright microscope. Due to RBC’s membrane being poorly reflective for visible wavelengths, quantitative information in the signal is weak and therefore, the quality of experimental results is limited in comparison to results obtained in transmission mode by various holographic techniques reported elsewhere.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.26 no.1
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• pp.1-7
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• 1990

Theoretical evaluations of the vertical displacement at the epicenter on the circular glass plate have been carried out in the case of the unit point loading(1 dyne force strength) with the Heaviside step-function time dependency. Acoustic emission signals generated during pencil lead($\Phi$=0.5mm, HB) fracture on the soda-lime glass($\Phi$=22cm, thickness=2.8cm) were observed by the optical Michelson interferometer with the stabilized circuit, and then the source function of the observed acoustic emission signals was analyzed by the deconvolution method. The source function of acoustic emission during pencil lead fracture had a 'dip' of~0.7$\mu$sec duration time at the front portion and a step function of~0.5$\mu$sec rise time with a force strength of~4.5N.

• Korean Journal of Optics and Photonics
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• v.11 no.5
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• pp.306-311
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• 2000

This paper deals with the development of Laser Doppler Vibrometer (LDV) that can mea~ure the tlequency and amphlude of the ultrasonic vibralion. Hc-Ne laser (632.8 om) is used as a light source, and Michelson interferometer in winch frequency of the objective beam is shIfted by Bragg cell IS adopted The frequency modulated signal centered at 40 MHz flom the PIN diode IS amplified. down-col1vel1ed to 2.5 MHz, filtered and digiLized. The voltage output that is proportional to the velocity of the vibratwg surface is obtawed using digItal PLL. A microprocessor is used to extract the frequcncy aud amplitude of the vibratIOn from the voltage output. It is found that the developed LDV can measure up to 300 kHz vibratIOn and the mlillmUITI measurable amplitude is I nm at 300 kHz. We believe thatlhis LDV can be used to measure the vibratIOn of the heavy electric maclllnery and micro-size structures. tures.