• Korean Journal of Optics and Photonics
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• v.31 no.1
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• pp.20-25
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• 2020

To design a wide-field two-mirror system, the system must feature an off-axial field, to avoid ray obstruction and field screening by the secondary mirror. The off-axial aberrations of the system cannot be corrected sufficiently, though, because there are only a few design parameters. The present study designs an improved off-axial-field two-mirror system using a decentered aperture stop.

• Journal of the Korea Fashion and Costume Design Association
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• v.13 no.1
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• pp.99-112
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• 2011

The purpose of this research is to study India's traditional embroidery method, Mirror Work, and to evaluate the examples of contemporary costumes as well as the applications of art to clothing that have been influenced by this technique, in order to expand its usage for creation of a new fashion image. Research in the literature and application of works related to Mirror Work have demonstrated: First of all, as a traditional embroidery method that represents the folk art of India, Mirror Work displays unique methods used in different regions and the way that various methods and materials were combined by the use of mirrors, beads, and $appliqu{\acute{e}}$. Secondly, it was found that the presentation of Mirror Work in the $pr{\hat{e}}t$-a-porte collection is based on a traditional embroidery method using both developed materials and adapted methods to express traditional reproducibility, geometric simplicity, and aesthetic characteristics of complex decorations. Thirdly, new plasticity for art to wear clothing can be created through various methods aside from embroidery, for example by a technique of wrapping crochet laces and tapes around the mirror for decorative purposes. Based on these results it can be inferred that, from the perspective of multiple forms for decorations, Mirror Work shares multiple forms of personal aesthetic goals through the mirror's unique quality for expression and enhanced images of artistic decorative art. Also, the introduction of traditional materials and methods for today's folk art and traditional costumes can be the subject of unique aesthetic characteristics based on different perspectives of the recreation of tradition. Finally, it can further create a new plasticity within the globalization phenomena.

• Current Optics and Photonics
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• v.1 no.4
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• pp.364-371
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• 2017

Compared to one made of glass, an aluminum mirror features light weight, compact design, low cost, and quick manufacturing. Reflective mirrors and supporting structures can be made from the same material, to improve the athermal performance of the system. With the rapid development of ultraprecise machining technologies, the field of applications for aluminum mirrors has been developed rapidly. However, most of them are rotationally symmetric in shape, and are used for infrared applications. In this paper, the design and manufacture of an off-axis aluminum mirror used for a three-mirror-anastigmat (TMA) optical system at visible wavelengths is presented. An optimized, lightweight design provides a weight reduction of more than 40%, while the surface deformation caused by earth's gravity can meet the required tolerance. The two pieces of an off-axis mirror can be diamond-turned simultaneously in one setup. The centrifugal deformation of the off-axis mirror during single-point diamond turning (SPDT) is simulated through the finite-element method (FEM). The techniques used to overcome centrifugal deformation are thoroughly described in this paper, and the surface error is reduced to about 1% of the original value. After post-polishing, the form error is $1/30{\lambda}$ RMS and the surface roughness is better than 5 nm Ra, which can meet the requirements for visible-light imaging.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.6
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• pp.1194-1202
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• 2002

A study on the topology optimization of a multi-spectral camera for space-use is presented. The optimization is carried out under self-weight and polishing pressure loading. A multi-spectral camera for space-use experiences degradation of optical image in the space, which can not be detected on the optical test bench on the earth. An optical surface deformation of a primary mirror, which is a principal component of the camera system, is an important factor affecting the optical performance of the whole camera system. In this study, topology optimization of the primary mirror of the camera is presented. As an objective function, a measure of Strehl ratio is used. Total mass of the primary mirror is given as a constraint to the optimization problem. The sensitivities of the objective function and constraint are calculated by direct differentiation method. Optimization procedure is carried out by an optimality criteria method. For the light-weight primary mirror design, a three dimensional model is treated. As a preliminary example, topology optimization considering a self-weight loading is treated. In the second example, the polishing pressure is also included as a loading in the topology optimization of the mirror. Results of the optimized design topology for the mirror with various mass constraints are presented.

• Design & Manufacturing
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• v.12 no.1
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• pp.36-40
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• 2018

The car requires an inside mirror installed between the driver's seat and the passenger's seat to ensure the driver's rear and side view of the driver. Inside mirrors must always be attached to the vehicle to ensure the driver's visibility. Inside mirrors attached to the windshield of a vehicle are always exposed to direct sunlight and should be semi-permanently usable in hot and humid summer weather in Korea. Therefore, the mirror mount, which is the junction of the inside mirror, is particularly important in corrosion resistance and wear resistance suitable for humidity. Mirror mounts are currently difficult to manufacture due to their reliance on powder molding technology in advanced countries such as Japan and Germany. This paper focuses on the fabrication of high corrosion resistant stainless mirror mounts by vacuum sintering technique and focuses on the selection of materials suitable for the production of mirror mounts through experiments of 300 series stainless steel and 400 series stainless steel manufactured by vacuum sintering.

• Journal of the Optical Society of Korea
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• v.19 no.6
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• pp.604-613
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• 2015

An unobstructed off-axis two-mirror system is presented in this paper. First a suitable initial configuration is established based on third-order aberration theory. In order to achieve a wide field of view (FOV) with high image quality , the diffractive mirror is adopted in the two-mirror system to increase the optimization freedom and the aberration relationship between diffractive phase coefficients and Zernike coefficients is derived. Furthermore, a complete comparison design example with a focal length of 1200 mm, F-number of 12, and FOV of 40° × 2° is given to verify the aberration correction ability of the diffractive mirror. The system average wavefront error is 0.007 λ (λ=0.6328 μm) developed from 0.061 λ when the system didn’t adopt the diffractive mirror. In this system the phase modulation function of the diffractive mirror is established as an even function of x, so we could obtain a symmetrical imaging quality about the tangential plane, and the symmetric aberration performance also brings considerable convenience to alignment and testing for the system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.205-208
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• 2005

Fabrication of large scaled mirror for the telescope application is the most challenging technology in recent year. Sophisticate technologies and know-how in fabrication and measurement are required to overcome the technological obstacles. KRISS(Korea Research Institute for Standards and Science) is now developing a large scaled mirror fabrication facility and KARI(Korea Aerospace Research Institute) is supporting the development. High precision interferometric test is required during the grinding and polishing of mirror to identify the surface profile precisely. The required fabrication accuracy of the mirror surface profile is $\lambda$/50 ms($\sim$10 nm for visible wave length). Thus the measurement accuracy should be far less than 10 m. To get this requirement, it is necessary to provide vibration free environment for the interferometer system and mirror under test. Thus the vibration responses on the mirror supporting table due to external vibration should be minimized by using a special isolation system. And the responses on the top of the tower, which hold the interferometer during test, should be minimized simultaneously. In this paper, we propose the concept design of vibration suppression system for the KRISS mirror fabrication facility.

• Journal of the Optical Society of Korea
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• v.16 no.4
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• pp.343-348
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• 2012

This paper described an off-axis five-mirror-anastigmatic telescope. It is composed of three aspheric surfaces and one spherical surface while the third mirror and fifth mirror have the same parameters at the same place. This configuration is useful for having wide field of view. The strip full field of view for the near infrared telescope is $20^{\circ}{\times}0.2^{\circ}$. The entrance pupil is located in front of the first mirror. There is an intermediate image between the second mirror and the third mirror. The entrance pupil diameter is 100 mm and the effective focal length is 250 mm. The spectral range is $0.85-1.75{\mu}m$. The pixel pitch is $15{\mu}m$. The image quality is near the diffraction limit. Some methods were used to restrain the stray light such as a field stop near the intermediate image, the baffle, the narrow-band pass filter and a stop in front of the focal plane.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.6
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• pp.198-206
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• 1999

An automobile outside rear view mirror system has been analyzed and designed to reduce vibration with a finite element model. model analysis is conducted for the calculation of natural frequencies. harmonic analysis is utilized to estimate the displacements of the glass surface under dynamic loads. The model is verified with the vibration experiment of the parts and the assembled body. The structure of the mirror system is optimized for the robustness defined by the Taguchi concept. At first, many potential design variables are defined. Final design variables are selected based on the amount of contribution on the objective function. That is, sensitive variables are chose. The SN ratio in the Taguchi method is replaced by an objective function with the mean and the standard deviation of the quality characteristic. The defined objective function is appropriate in the structural design in that the vibration displacements are minimized while the robustness is improved.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.59-64
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• 2002

One of the exciting research areas of the X-ray microscope is the observation of a living cell. In order to study a living cell with high resolution the order of the several tens nm, we need to improve the efficiency of mirrors which are components of an X-ray microscope system. In this paper we present the mirror design and manufacture to give a high resolution and reflectivity. We designed Wolter type I the condenser and objective mirror with the several tens of nm resolution. According to mirror design. we made the program using the visual basic. Using the new processing method as well as the ultra-precision diamond cutting, we directly processed the inside of an aluminum hulk in order to manufacture mirrors. From the experimental result, we think that the new processing method will improve a high reflectivity through the improved cutting tools and optimum cutting conditions.