• Korean Journal of Optics and Photonics
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• v.9 no.4
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• pp.245-250
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• 1998

A new computational algorithm is presented for the peak point detection of white light interferograms. Assuming the visibility function of white light interferograms as a quadratic polynomial, the peak point is searched so as to minimize the error sum between the measured intensity data and the analytical intensity. As compared with other existing algorithms, this new algorithm requires less computation since the peak point is simply determined with a single step matrix multiplication. In addition, a good robustness is obtained against external random disturbances on measured intensities since the algorithm is based upon least squares principles.

• Journal of the Optical Society of Korea
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• v.17 no.4
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• pp.317-322
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• 2013

We have proposed and demonstrated a low numerical aperture technique to measure the depth of through silicon vias (TSVs) using white-light scanning interferometry. The high aspect ratio hole like TSV's was considered to be impossible to measure using conventional optical methods due to low visibility at the bottom of the hole. We assumed that the limitation of the measurement was caused by reflection attenuation in TSVs. A novel interference theory which takes the structural reflection attenuation into consideration was proposed and simulated. As a result, we figured out that the low visibility in the interference signal was caused by the unbalanced light intensity between the object and the reference mirror. Unbalanced light can be balanced using an aperture at the illumination optics. As a result of simulation and experiment, we figured out that the interference signal can be enhanced using the proposed technique. With the proposed optics, the depth of TSVs having an aspect ratio of 11.2 was measured in 5 seconds. The proposed method is expected to be an alternative method for 3-D inspection of TSVs.

• Proceedings of the Optical Society of Korea Conference
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• 2006.02a
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• pp.209-210
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• 2006

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.12
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• pp.2341-2346
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• 2017

The relative position of the eyeballs in the orbit can be a criterion for estimating multiple pathological conditions. Especially, it is useful to diagnose orbital fracture, thyroid eye disease, orbital tumor, and to evaluate the result of drug and surgical treatment. The Hertel and Naugle exophthalmometer, which are the most commonly used measuring instruments for measuring the prominence of the eye, are different from each other. Even if the same examiner repeatedly measures, it is inevitable. Also, even if the same exophthalmometer is different from the manufacturing company, the design of the fixed part of the orbit is different, and a measurement error is caused by the inspectors. In this paper, we propose a method of automatic measurement that can increase the accuracy and repeatability of measurement of exophthalmos using white light scanning interferometer, which is a 3D image measurement technique.

• Journal of Technologic Dentistry
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• v.35 no.1
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• pp.37-42
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• 2013

Purpose: The purpose of this study was to evaluate the repeatability of dental white light scanner. Methods: The impression(Zerosil, Dreve, Germany) were digitized in white light scanner(Identica, Medit, Korea) to create 3-dimensional surface-models. The distribution of the discrepancies between the number of points in the corresponding CRM models and the point clouds in the others were measured by a matching-software(PowerInspect 2012, Delcam Plc, UK). The discriptive statistics were used for statistical analysis(SPSS 20.0). Results: The measurement of repeatablity showed very good reliability. The mean(SD) discrepancy value on the white light scanner digital models was 8.7(0.67) ${\mu}m$, based on SD and absolute mean values. Conclusion: These in vitro studies showed that repeatability of dental white light scanner is high reliability. These results can be confirmed in further clinical studies.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.6
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• pp.519-522
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• 2008

As industry of a semiconductor and LCD industry have been rapidly growing, precision technologies of machining such as etching and 3D measurement are required. Stylus has been important measuring method in traditional manufacturing process. However, its disadvantages are low measuring speed and damage possibility at contacting point. To overcome mentioned disadvantage, non-contacting measurement method is needed such as PMP(Phase Measuring Profilometry), WSI(white scanning interferometer) and Confocal Profilometry. Among above 3 well-known methods, WSI started to be applied to FPD(flat panel display) manufacturing process. Even though it overcomes 21t ambiguity of PMP method and can measure objects which has specular surface, the measuring speed and vibration coming from manufacturing machine are one of main issue to apply full automatic total inspection. In this study, We develop high speed WSI system and algorithm to reduce unknown noise. The developing WSI and algorithm are implemented to measure 3D surface of wafer. Experimental results revealed that the proposed system and algorithm are able to measure 3D surface profile of wafer with a good precision and high speed.

• Korean Journal of Materials Research
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• v.21 no.1
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• pp.46-49
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• 2011

Bi co-doped ZnS:Mn,Bi yellow phosphors for white light emitting diodes were prepared by the conventional solidstate reaction method. The optical and structural properties of ZnS:Mn,Bi phosphors were investigated by x-ray diffraction, scanning electro microscopy and photoluminescence. ZnS:Mn,Bi phosphors showed XRD patterns of hexagonal structure. The photoluminescence of ZnS:Mn,Bi phosphors showed spectra extending from 480 to 700 nm, peaking at 580 nm. The photoluminescence of 580 nm in the ZnS:Mn,Bi phosphors was associated with the 4T1 ${\rightarrow}$ 6A1 transition of the Mn2+ ions. The highest photoluminescent intensity of the phosphors under 405 nm and 450 nm excitation was obtained at Bi concentration of 7mol%. The optimum mixing conditions with epoxy and yellow phosphor for white light emitting diodes were observed in a ratio of epoxy:yellow phosphor of 1:3.5. The CIE chromaticity of the white LED at the 1:3.5 ratio was X = 0.3454 and Y = 0.2449.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.9 s.186
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• pp.102-110
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• 2006

We discuss two possibilities of using femtosecond pulse lasers as a new interferometric light source for enhanced precision surface-profile metrology. First, a train of ultra-fast laser pulses yields repeated low temporal coherence, which allows unequal-path scanning interferometry, which is not feasible with white light. Second, the high spatial coherence of femtosecond pulse lasers enables large-sized optics to be tested in nonsymmetric configurations with relatively small-sized reference surfaces. These two advantages are verified experimentally using Fizeau and Twyman-Green type scanning interferometers.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.917-918
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• 2013

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.61-62
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• 2007