• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.573-576
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• 2005

A compact linear and angular displacement measurement device was developed by combining a Michelson interferometer and an autocollimator to characterize the movement of a precision stage. A Michelson interferometer and an autocollimator are typical devices for measuring linear and angular displacement, respectively. By controlling the polarization of reflected beam from the target mirror of the interferometer, some part of light was retro-reflected to the light source and the reflected beam was used for angle measurement. The interferometer and the autocollimator use the same optic axis and the target mirror can be easily and precisely aligned orthogonal to the optic axis by monitoring the autocollimator s signal. The autocollimator was designed for angular resolution of 0.1 arcsec and dynamic range of 60 arcsec. The nonlinearity error of interferometer was minimized by trimming the gain and offset of the photodiode signals. Through the experiments, we evaluate the performance of measurement device and discuss its applications.

• Journal of the Korean Society for Precision Engineering
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• v.4 no.4
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• pp.36-42
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• 1987

Very accurate calibration is needed to index tables which are necessary for precision angle measurement. The repeatability of index table is less than 0.2 second, so that attentions should be paid to choosing devices to be used in the calibration of index tables. The auto- collimators have been used in the calibration of index tables, but the repeatability of auto- collimators is bad compared with that of index table. In place of autocollimators, we described a method which uses electric comparators which are possessed by most precision measurement laboratories. Electric comparators are set to measure small angle displacement without interrupting the rotation of index tables and the signals of two electric comparators are added to remove the run-out errors of the shafts of index tables. Two index tables have been calibrated simulataneously by this method and the measurement data have been analyzed by the least squares method. We compare the calibration results with those of methods using autocollimator and auto- matic autocollimator and are able to know that the data of electric comparator method lie between the data of autocollimator methods. The repeatability of measurement is less than 0.02 second. The electric comparator method is economical and capable of reducing the uncertainty of the measurement.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.264-270
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• 1996

In this paper, a computer automated system has been developed for measuring the focal length of camera lens using the MTF(Modurar Transfer Function) based on the signal processing around a line CCD and autocollimator. An optical Path for the focal length measurement system has been designed around thelight sourec, collimator, camera, mirror and the line CCD. The eyepiece of the collimator is replaced byline CCD, and the mirror is moved along the focal axis by a PC driven step motor. An efficient method has been designed for finding the optimum MTF value for the focal length based on the least squares approach. The developed system is fullycomputer automated: signal transmission to and from the camera, MTF evaluation based on the line CCD, step motor contorl, etc. The developed system has been applied to a practical camera manufacturing process and demonstrated its performance

• Proceedings of the Optical Society of Korea Conference
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• 2006.07a
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• pp.449-450
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• 2006

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.940-944
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• 2004

This is a thesis about the Solid Coupling Design and Torsional Angular Error Character. The solid coupling which is designed and made is a strong rigidity material. This is a experiment of Solid Coupling Torsional Error. The Angular Error, FEM and Circularity Measurement. Devices are Twist Friction Driver, Polygon, Autocollimator and Standard Encoder for Measurement. Coupling caused by elastic deformation causes angular error.

• Korean Journal of Optics and Photonics
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• v.15 no.3
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• pp.254-257
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• 2004

A null optical system for monitoring the alignment of the optical beam director is proposed instead of the conventional autocollimator alignment system. A null optical system for the optical beam director of aperture 30 cm is designed and its performance is analysed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.636-642
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• 1996

본 연구는 4축 또는 5축 NC 공작기계에 사용되는 Rotary Table의 오차를 측정하고 이를 보정하기 위한 연구이다. 먼저 일반적인 Rotary Table에 대한 오차모델이 설정되었으며, Rotary Table에서 존재하는 6가지의 오차를 각각 측정하였다. 측정방법은 3개의 길이오차는 1 개의 정밀볼(Master ball)과 3개의 LVDT, 3개의 각도 오차는 6각 폴리곤과 Autocollimator를 사용하여 측정하였다. 측정된 오차 성분들은 오차모델을 이용하여 보상치를 계산하였으며, 이 값은 추후 원래의 측정오차와 비교하는 방법으로 모델의 정확성을 검증할 것이다. NC 공작기계상에서 Rotary Table의 실제 보상 실험을 위하여 30$^{\circ}$간격으로 정밀한 볼이 장착된 볼-테이블을 설계하였다.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.8
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• pp.71-80
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• 1998

A computer aided system has been developed for the focal length measurement/compensation in camera manufacture. Signal data proportional to light intensity is obtained and sampled very rapidly from the line CCD. Based on the measured signal, the MTF performance is calculated, where the MTF is the ratio of magnitude of the output image to the input image. In order to find the optimum MTF performance, an effcient algorithm has been implemented using the least squares technique. The developed system has been applied to a practical camera manufacturing process, and demonstrated high productivity with high precision.

• Korean Journal of Optics and Photonics
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• v.2 no.1
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• pp.7-12
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• 1991

A nondestructive technique for measuring the refractive index of a simple lens is described. The shearing interferornetric technique is used for determining the focal length of a lens by immersing it in various liquids. The lens itself acts as autocollimator and decollimator. An equation for the defocusing error has been theoretically deduced and experimentally verified. The wave aberration has also been investigated for the different values of the focal length.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1438-1441
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• 2005

To establish of standard technique of nano-length measurement in 2D plane, new AFM system has been designed. In this system, measurement uncertainty is dominantly affected by the Abbe error of XY scanning stage. No linear stage is perfectly straight; in other words, every scanning stage is subject to tilting, pitch and yaw motion. In this paper, an AFM system with minimum offset of XY sensing is designed. And XY scanning stage is designed to minimize rotation angle because Abbe errors occur through the multiply of offset and rotation angle. To minimize the rotation angle optimal design has performed by maximizing the stiffness ratio of motion direction to the parasitic motion direction of each stage. This paper describes the design scheme of full AFM system, especially about XY stage. Full range of fabricated XY scanner is $100um\times{100um}$. And tilting, pitch and yaw motion are measured by autocollimator to evaluate the performance of XY stage. Using this AFM system, 3um pitch specimen was measured. As a result, the uncertainty of total system has been evaluated.