• Journal of Korea Multimedia Society
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• v.21 no.8
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• pp.864-875
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• 2018

In this paper, we propose a measurement method for height of white light scanning interferometer using deep learning. In order to measure the fine surface shape, a three-dimensional surface shape measurement technique is required. A typical example is a white light scanning interferometer. In order to calculate the surface shape from the measurement image of the white light scanning interferometer, the height of each pixel must be calculated. In this paper, we propose a neural network for height calculation and use virtual data generation method to train this neural network. The accuracy was measured by inputting 57 actual data to the neural network which had completed the learning. We propose two new functions for accuracy measurement. We have analyzed the cases where there are many errors among the accuracy calculation values, and it is confirmed that there are many errors when there is no interference fringe or outside the learned range. We confirmed that the proposed neural network works correctly in most cases. We expect better results if we improve the way we generate learning data.

• Journal of the Korean Institute of Intelligent Systems
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• v.22 no.6
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• pp.694-699
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• 2012

In this paper, semiconductor package inspection results using white light interferometer with large F.O.V., in order to apply semiconductor product inspection process, are shown. Experimental 3D data repeatability test results for the same special bumps of each substrate are shown. Experimental 3D data repeatability test results for all the bumps in each substrate are also shown. Semiconductor package inspection using white light interferometer with large F.O.V. is very important for the fast 3D data inspection in semiconductor product inspection process. This paper is surely helpful for the development of in-line type fast 3D data inspection machine.

• Korean Journal of Optics and Photonics
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• v.15 no.4
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• pp.331-336
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• 2004

The phase change due to the reflection from target surfaces in a white-light interferometer induces measurement errors when target surfaces are composed of dissimilar materials. We prove that this phase change on reflection as the polarization of the white-light changes causes a shift of both envelope peak position and fringe peak position of several tens of nanometers as the polarization of the white-light changes. In addition, we propose a new equation for white-light interference fringes depending on the polarization of the source.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.531-532
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• 2012

• Journal of the Korean Institute of Intelligent Systems
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• v.23 no.4
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• pp.286-291
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• 2013

In this paper, in-line type flip chip bump 3D inspection equipment, using white light interferometer with large F.O.V., which is aimed to be used in flip chip bump test process is developed. Results of flip chip bump height measurement in many substrates and repeatability test results for the bumps in fixed location of each substrate are shown. Test results from test bench and those from developed flip chip bump 3D inspection equipment are compared and as a result repeatability is improved by reducing the impact of system vibration. A valuation basis for the testing quality of flip chip bump 3D inspection equipment is proposed.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.7
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• pp.702-708
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• 2013

The white-light scanning interferometer (WSI) is an effective optical measurement system for high-precision industries (e.g., flat-panel display and electronics packaging manufacturers) and semiconductor manufacturing industries. Its major disadvantages include a slow image-capturing speed for interferogram acquisition and a high computational cost for peak-detection on the acquired interferogram. Here, a WSI system is proposed for the semiconductor inspection process. The new imaging acquisition technique uses an 'on-the-fly' imaging system. During the vertical scanning motion of the WSI, interference fringe images are sequentially acquired at a series of pre-defined lens positions, without conventional stepwise motions. To reduce the calculation time, a parallel computing method is used to link multiple personal computers (PCs). Experiments were performed to evaluate the proposed high-speed WSI system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.175-178
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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 the Naugle exophthalmometer, which are typical measuring instruments used mainly to measure the protrusion of the eye, are inevitably error by the measurer. In this paper, we propose a method to increase the accuracy and repeatability of the measurement of eyeball exophthalmometric values by using a white light interferometer.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.195-198
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• 2002

Demand for high precision measurement of large area is increasing in many industrial fields. White-light Scanning Interferometer(WSI) is a well-known method for 3D profile measurement. However WSI has some limitations in a measurement range because of the sensing mechanism. Therefore, in this paper we use a heterodyne laser interferometer to get over the limitations of a short measurement range in WSI, We suggest a new WSI system combined with heterodyne laser interferometer. This system is aimed at eliminating Abbe error with measuring the focus point directly. With the use of triggering functionality of WSI, we can use this system as a probe of a precision stage such as a probe of CMM. The suggested system gives a repeatability of 87 nm in the absolute distance measurement test under the laboratory environment.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.110-113
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• 2001

We present an interferometer system, which is able to perform both the phase shifting interferometry and white light interferometry. The interferometer system uses a d.c. motor to control the probe position with an accuracy of 10nm, which shows an outstanding performance on white light interferometry. However, the moving mechanism of d.c. motor is not accurate enough for the phase shifting interferometry that requires a moving precision less than 1 nm. We therefore propose a Fourier transform technique to calculate the phase of interferograms, which is strongly resistant to calibration errors and external vibration. Experimental results show that the Fourier transform technique is capable of reducing the measurement error caused by inaccurate movement within 0.1nm.

• Current Optics and Photonics
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• v.1 no.6
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• pp.604-612
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• 2017

An effective and precise method using a scanning white-light interferometer (SWLI) for three-dimensional surface measurements, in particular for roughness measurements, has been proposed. The measurement of a microscopically sloped area using an interferometer has limitations, due to the numerical aperture of the lens. In particular, for roughness measurements, it is challenging to obtain accurate height data for a sloped area using the interferometer, due to diffraction of the light. Owing to these optical limitations of the interferometer for roughness measurements, the Ra measurements performed using an interferometer contain errors. To overcome the limitations, we propose a method consisting of the following two steps. First, we evaluate the height data and set the invalid height area to be blank, using the characteristics of the modulus peak, which has a low peak value for signals that have low reliability in the interferogram. Next, we interpolate the blank area using the adjacent reliable area. Rubert roughness standards are used to verify the proposed method. The results obtained by the proposed method are compared to those obtained with a stylus profilometer. For the considered sinusoidal samples, Ra ranges from $0.053{\mu}m$ to $6.303{\mu}m$, and we show that the interpolation method is effective. In addition, the method can be applied to a random surface where Ra ranges from $0.011{\mu}m$ to $0.164{\mu}m$. We show that the roughness results obtained using the proposed method agree well with profilometer results. The $R^2$ values for both sinusoidal and random samples are greater than 0.995.