• Journal of Engineering Education Research
• /
• v.16 no.2
• /
• pp.24-30
• /
• 2013

This paper deals with the measurement theory and technique of linear expansion coefficient for solid material using Michelson interferometer. The Michelson interferometer produces interference fringes by splitting a beam of monochromatic light so that one beam strikes a fixed mirror and the other a movable mirror. When the reflected beams are brought back together, an interference pattern results. Precise distance measurements until a quarter of wave length can be made with the Michelson interferometer by moving the mirror and counting the interference fringes which move by a photo diode. This paper represents the application of Michelson interferometer for measuring infinitesimal length system and shows the measurement method of linear expansion coefficients for various materials like copper, aluminum and iron. the results are good agreement with theoretical value within margin of error for each materials.

• Proceedings of the KIEE Conference
• /
• 1988.07a
• /
• pp.418-421
• /
• 1988

Holographic interferometry is applied in dental research to study the motion of teeth and the deformation of the associated facial structure. We consider double exposure holographic interferometry which has limiting factors such as the stability of fringes, the recording time, the amount of exposure, the localization of fringes and sensitivity. These factors are taken into account to make interferogram. The resulting interferogram gives fringe pattern which is analyzed qualitatively to determine the relative rotation and the deformation of the facial structure.

• Journal of the Optical Society of Korea
• /
• v.16 no.2
• /
• pp.121-126
• /
• 2012

We propose a novel technique that records the horizontal-parallax-only (HPO) hologram of a real object using optical scanning holography (OSH). The proposing HPO-OSH is composed of a conventional OSH and an electronics low pass filter. When we scan an object along vertical direction before horizontal direction, the electronic low pass filter filters the vertical fringes with preserving horizontal fringes and gives an HPO hologram. To the best of our knowledge, this is the first time to record the HPO hologram using OSH without either truncation of the scanning beam or digital post processing.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.16 no.8
• /
• pp.1530-1535
• /
• 1992

An optical method of phase shifting interferometry is presented for the 3-dimensional profile measurement of mirror surfaces with nanometer resolution. A series of optical interferometric fringes are generated by comparing the surface to be measured with a reference flat. The fringes are captured by a CCD camera and then analyzed to obtain actual surface profile. Detailed principles are described along with necessary image processing algorithms. finally, several measurement examples are discussed which were performed on lapped surfaces, hard discs, and semiconductor wafers.

• Tribology and Lubricants
• /
• v.16 no.5
• /
• pp.317-323
• /
• 2000

The film thickness and shape of elastohydrodynamic lubrication is measured by optical interferometer, which is the most precise method for EHL film measurement. However, the interpretation of the image pattern from optical viscometer is not simple for two-dimensional shape. A newly developed method of image processing makes it possible to evaluate the film thickness and shape in every point of contact region with two dimensional aspects. In this study, we captured the film shape of EHL film by the monochromatic incident light and analyzed the film thickness with the image processing method, which uses phase shift method. From the values of intensity in fringes, the qualitative feature of film thickness in the contact area are obtained by using Zernike polynomial

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.21 no.6
• /
• pp.995-1001
• /
• 1997

In this paper, a new positioning method with incoherence of white light is described and practically implemented to attach VCR heads on a drum very accurately. This method utilizes the Michelson Interferometer which uses white light with short coherence length as the light source to generate interference fringes only in case the optical path difference is shorter than about 2.mu.m. The course position of VCR heads and the fine are determined by appearance and visibility of interference fringes, respectively. The appearance are detected by an image processing technique using FFT(Fast Fourier Transform).

• Journal of Integrative Natural Science
• /
• v.5 no.1
• /
• pp.13-17
• /
• 2012

Changes of Fabry-Perot fringe patterns in porous silicon during etching process has been investigated. Four porous silicon samples were prepared with four different etch currents: (a) 10 $mA/cm^2$, (b) 30 $mA/cm^2$, (c) 50 $mA/cm^2$, (d) 100 $mA/cm^2$, respectively. Optical characterization of Fabry-Perot fringe pattern on porous silicon was achieved by Ocean optics 2000 spectrometer. The change of Fabry-Perot fringes was monitored and measured during the etching process. Fabry-Perot fringes pattern start to form after couple of minutes. As the etching time increased, more reflection peaks were observed. Its full width at half maximum (FWHM) decreased rapidly when the etching time increased.

• Journal of the Optical Society of Korea
• /
• v.14 no.1
• /
• pp.33-37
• /
• 2010

The joint transform correlator (JTC) has been the best known technique for pattern recognition and identification. The JTC optically compares the reference image with the sample image then examines match or non-match by acquiring a correlation peak. However, the JTC technique has some problems such as weak correlation discrimination and noise which originates from the interference fringes in the Fourier transform plane. In order to solve these problems, this paper proposes a new technique of modifications of the interference fringes by adopting special iterative filters. Experimental results are presented to show that the proposed technique can successfully improve the correlation peaks and the level of discrimination.

• Proceedings of the Optical Society of Korea Conference
• /
• 1997.08a
• /
• pp.79-79
• /
• 1997

• The korean journal of orthodontics
• /
• v.24 no.2
• /
• pp.447-476
• /
• 1994

This study was performed to evaluate the initial reaction of maxillofacial complex to the Class II intermaxillary and the anterior vertical elastic forces on the six types of archwires including multiloop edgewise arch wires(MEAW). A human dry skull was used for this purpose and this investigation was done by holographic interferometry. Based on such investigation, the fringe pattern and the number of fringes of each condition were compared and analyzed. The findings of this study were as follows: 1. As the orthodontic forces increased, the amount of displacement increased. 2. As the orthodontic forces were applied, the fringes were shown not only in the teeth and the maxilla but also in the adjacent bones, i.e., temporal bone, zygomatic bone, nasal bone, frontal bone and sphenoid bone. And the direction of fringe pattern and the number of fringes were different from each other by the sutures. 3. As the long Class II elastic forces were applied, the backward-downward displacements of the anterior teeth and the maxilla were shown, and backward displacement of the former were grater than those of the latter. And backward displacements were greater by the long Class II elastic forces than by the short Class II elastic forces. 4. As the anterior vertical elastic forces were applied, downward displacements of the anterior teeth and the maxilla were shown, and the downward displacements of the former were greater than those of the latter relatively. 5. The downward displacements of the anterior area to the anterior vertical elastic forces of the MEAW were greater than those of other archwires. In addition, the more tip-back bend was applied, the more displacement was seen. 6. As the Class II intermaxillary forces and the enough anterior vertical elastic forces were applied on the MEAW with tip-back bend, there was an intrusive effect of the posterior teeth.