• Journal of Korean Ophthalmic Optics Society
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• v.8 no.2
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• pp.177-183
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• 2003

We tried to design and manufacture an iris photographing optical-system which is used in the Oriental medicine or medical diagnostics. The whole system consists of a light source part, an image focusing part, a CCD transfer part and a diagnosis S/W. We designed the image focusing part to the reduction optical-system with 0.58X magnification of which the chromatic aberration is removed by using materials of FD60 and BACD5. The image focusing part's localization did big contribution in coot reduction of products. The manufactured iris photographing optical-system had superior performance in aspect that has stereoscopic effects of images in comparison with the foreigner's.

• Journal of Magnetics
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• v.8 no.1
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• pp.45-49
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• 2003

We present a brief review of recent experimental and theoretical results on new magneto-optical phenomena in magnetic granular metal-insulator alloys with tunnel-type magnetoresistance, focusing on magnetorefractive effect and cubic nonlinear magneto-optics.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.432-435
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• 2005

The Mega-pixel camera phones become main trends in mobile phone market. The lens modules used in mesa-pixel camera phones need high resolution. One of the main factors of resolution drop is the defects of bare lens. Though there are many advantages in auto-inspection of defects of bare lens, high technical problems take the defect inspections to be done with manual process. In this paper, the type and the source of defects were described and bare lens defect auto-inspection system design was explained. The designed auto-inspection system is composed of illumination optics part, focusing optics part and auto-moving system. With the proposed auto-inspection system, fast and uniform inspection of bare lens can be achieved.

• Journal of the Optical Society of Korea
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• v.7 no.3
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• pp.193-196
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• 2003

We have developed a laser welding monitoring system to monitor laser welding process conditions such as sample feed rate, laser focal position, and laser power. A 2 ㎾ Nd:YAG CW laser beam has been applied to the welding of a stainless steel plate (SUS306) to investigate the welding monitoring. Theradiation signal from the weld pool was guided back through the focusing optics and the laser delivery fiber, and measured by a photo detector. By changing the focus of the laser beam along the z-direction, the penetration depth of the welding material has been measured. That shows the penetration depth depends on the frequency fluctuations of the plume signals which can be used in welding quality control.

• Journal of the Optical Society of Korea
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• v.1 no.1
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• pp.23-25
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• 1997

In this paper we will show theoretically that a refractive index grating exhibits a retro-self-focusing effect and an accompanying pinholing effect under the Gaussian intensity distribution of an incident optical field. Those effects result from an effective wave number change of the medium due to the intense optical field.

• Korean Journal of Optics and Photonics
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• v.3 no.1
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• pp.11-15
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• 1992

In this work we analyze effects on the spectra of an integrated-mirror etalon by the absorption in a spacer layer, scattering loss at the interfaces between layers, and the focusing of incident beam.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.6
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• pp.96-101
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• 2020

In this paper, we present the results of our research to perform 3D laser scanning functions by adding a focusing lens to a conventional 2D laser scanner. For the optical design, the ray-tracing technique was used along with a total of four lenses as the variable incident focusing lens, the collimating lens, and the F-Theta lens. As design variables, the curvature of the incident focusing lens (Lens #1) was assumed to be us, l mm and sumed mm, and the incident angles were set at 0cidenus, l. In addition, the distance between the focusing lens and the collimating lens was set to vary from 5 mm to 15 mm. When the incident focal length was varied from 5 mm to 15 mm, the exit focal length was calculated to vary from 67.5 mm to 56.8 mm for the lens with R = 100 mm and from 108.5 mm to 99.0 mm for the lens with R = 150 mm. When the incident angle was 0°, the focal aberration was only slightly observable at 10㎛ in both the x- and y-direction. At 7.5° was the focal aberration of approximately 20~50㎛ was measured at 20㎛. To investigate the chromatic aberration of the designed optical device, the distortion of the focus was observed when the 550 nm beam was simulated on lens designed for a 980 nm wavelength.

• Analytical Science and Technology
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• v.18 no.6
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• pp.483-490
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• 2005

Mass resolution of the time of flight aerosol mass spectrometer for an aerosol component analysis depends on the initial direction and the initial energy of the ions. We have found that the shape of the optimum post focusing electric field is not linear. The maximum electric potential should be applied to the ions whose initial direction is 90 degree. To check on the post focusing effects, we have installed a laser ablation mass spectrometer. By using this LA-MS, we have found that the average energy distribution of the laser ablated ions is 8 eV. To establish the optimum mass resolution, a time delay and a high voltage are needed, and the results of the study show that 1500 nsec, and 3.7 kV are the optimum parameters for our system respectively. The isotope mass signals of copper show a good resolution.

• Current Optics and Photonics
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• v.5 no.4
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• pp.402-408
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• 2021

An off-axis system refers to an optical system in which the optical axis and normal vector at the vertex of each surface do not match. The most important specification in an optical system is its focal length. Among the various methods for measuring the focal length, the most suitable method for the off-axis system is the method that adopts magnification. However, head-mounted display (HMD) optics must be measured while considering the virtual image distance, which is not infinity owing to product characteristics. For the virtual image distance, a camera with a focusing function was used. By measuring HMD optics via this magnification method, the error generated in this measurement was 0.68% of the HMD's focal length, which is within the 1%-3% range of the conventionally permitted design error for the focal length allowed at the optical design stage. Therefore, it can be verified that the measurement accuracy of the method proposed in this study is sufficiently feasible in practice.

• ETRI Journal
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• v.29 no.6
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• pp.817-819
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• 2007

A low-stress organic polymer membrane is proposed as a deformable mirror that can be incorporated into a cellular phone camera to achieve auto focusing without motor-type moving parts. It is demonstrated that our fabricated device has an optical power of 20 diopters and can switch focus in 14 ms. The surface roughness of the organic membrane is measured around 15 nm, less than ${\lambda}$/20 of the visible light. With curve fitting, we found that the actuated membrane is almost parabolic in shape, which leads to less aberration than spherical surfaces. It is suitable for reflective-optics systems.