• Korean Journal of Optics and Photonics
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• v.5 no.2
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• pp.198-203
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• 1994

An improved method for the measuement of very long radius of curvature by using a bidirectional shearing interferometer in a noncollimated light beam is given. This method can be used for both lenses and surfaces with positive or negative power. Detailed analyses for optical arrangements and achievable accuracy are presented.sented.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.712-715
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• 2011

When simulate long distance infrared image in the laboratory the Infrared Refractive Collimator is used. In this case, infrared light reflected from the surface of the lens and target. The reflected infrared light causes Narcissus. Narcissus degrades the quality of the infrared image. To minimize Narcissus optimize the reflective index and placement of the lenses, lenses and target surface coated.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2009.04a
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• pp.41-48
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• 2009

Laser diode is used as a crucial part for minimization of terrestrial 3D Laser Scanner. But it has certain limitations such as oval beam shape and inevitable astigmatism. In order to realize a parallel light with beam divergence below 1 mrad, These problems of laser diode can be solved through beam shaping by Pinhole and Aperture. Finally, this study could materialize a collimated beam with 0.3 mrad beam divergence angle and 3mm diameter, that performance and checked by using real manufacture.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.2
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• pp.255-264
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• 2022

The conventional spot-type UV curing machine configures a collimator optical system using a plurality of lenses so that the light beam is incident through an optical cable. In order to increase the transmission light efficiency, a collimator optical system composed of three or more lenses is required, and accordingly, it is difficult to align the optical system, and it is difficult to implement the system compactly. In this study, a single TIR lens collimator that can realize the same level of spot diameter and light efficiency as the conventional collimator optical system composed of three lenses was designed. Through this, the light efficiency at the curing area with the minimum illuminance deviation was 33.2 %, which was similar to the performance of the reference collimator optical system, and the illuminance deviation on the curing area was 18.8 %, ensuring acceptable performance. In addition, by arranging a fly-eye lens with field flattening function at the front end of the condensing lens, the effective curing area diameter was reduced from 5.0 mm to 3.0 mm, enabling higher curing energy density to be realized. In addition, it was confirmed that the illuminance deviation can be greatly improved to a level of 14.4%.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.51-54
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• 2000

The traditional surface measuring method using confocal principle requires much time to measure an object surface since it is a scanning tool. In this paper, the upgraded confocal microscope is introduced. It is also a scanning tool but it requires 2D-scanning while the traditional one requires 3D-scanning. It means the time for measuring is considerably reduced. In addition, the measuring system is configured to increase the efficiency of beam. He-Ne laser whose frequency is 632.8nm is used for the laser source. An example of measuring result through the upgraded confocal microscope is showed.

• Korean Journal of Optics and Photonics
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• v.5 no.2
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• pp.304-310
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• 1994

The use of thermally expanded core (TEe) fibers fabricated by thermal diffusion of dopants such as $GeO_{2}$ in hybrid fiber components has an advantage of eliminating lenses for collimation and focusing. An electric furnace is fabricated to heat the fibers locally for the core expansion. We observed an expansion of the mode size at $1.3\mu\textrm{m}$ wavelength by 27% after treating a section of single mode optical fiber at $1250^{\circ}C$ for 10 hours. hours.

• Korean Journal of Optics and Photonics
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• v.17 no.2
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• pp.165-174
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• 2006

The autotstigmatic null lens system is designed and constructed for the fabrication of a parabolic mirror with the diameter of 450 mm(f/2.7). And the measurement reliability is also analyzed theoretically by means of the tolerancing technique using lens design software(CODE V). From this analysis, we can precisely fabricate a parabolic mirror with the large diameter of 450 mm(f/2.7). Meanwhile, in order to confirm the fabrication results by the autostigmatic method, the mirror surface is tested again by an autocollimating method that uses only a plane mirror without any null lens.

• Korean Journal of Optics and Photonics
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• v.13 no.2
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• pp.92-97
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• 2002

A real-time OTF (optical transfer function) measuring system with on- and off-axis nodal slide bench type for the camera lens is fabricated and evaluated. It consists of a nodal slide bench including a T-bar for the OTF measurement of an off-axis object, two dimensional CCD (charge coupled device) with pixel of 9.9${\mu}{\textrm}{m}$$\times$9.6${\mu}{\textrm}{m}$ for real-time OTF measurment, and a collimating lens of focal length of 300 mm for the optimization of this system. The OTF system is corrected by using the OTF of a SIRA lens of fnumber of F/8 and focal length 50 mm. In order to confirm the reliability of the OTF system, two MTFs (modulus transfer functions) of CCTV & VIDEO lens (JAPAN, AVENIR-SE 2514) of focal length of 25mm and field of view 10.6$^{\circ}$are measured by the camera bench type OTF system of reference OTF system and the nodal slide bench type OTF system and compared with each other. As a result, these two values are agree well with each other within 4% from 0 1p/mm to 100 1p/mm.

• Korean Journal of Optics and Photonics
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• v.7 no.3
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• pp.191-195
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• 1996

A optical system of a movile LIDAR is designed for air pollution research. After the inverse Cassegrain type collimator, the laser beam falls on the mirror which serve for coinciding optical axis of laser beam and the receiving telescope. Then, it is directed into the atmosphere and back scattered radiation back to the receiving telescope by the scanning mirror. The unit of scanning mirror allows to rotate the mirror along the altitude 0$^{\circ}$~60$^{\circ}$, and the azimuth 0$^{\circ}$~360$^{\circ}$. The scanning mirror is not connected with the receiving telescope but placed on the roof of the mobile. The received beam is spatial filtered by a spatial filter and collimated by a fabric lens. Thereafter, the beam is devided into 2 channel for registration by a beam splitter. Each laser beam is transformed into an electrical signal by means of the photomultifier and then processed to be analyzed.

• Korean Journal of Optics and Photonics
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• v.5 no.1
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• pp.51-59
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• 1994

We constructed travelling type Nd:YAG laser with a negative branch confocal unstable ring (NBCUR) resonator like a Newtonian telescope type using four flat mirror and two positive lenses. Annular output beam was obtained by using scraper mirror. This laser oscillator has 22 optical faces and optical alignment was done by equal inclination interferance method. We inserted a Faraday rotator of permanent magnet type designed in the laboratory for unidirectional operation. We obtained laser output energy of 80m.I with electrical input energy of 70 J. and we obtained that peak power of 0.5MW through Q-switching with BDN dye.