• 한국광학회지
• /
• 제13권5호
• /
• pp.442-448
• /
• 2002

지상용 천문 망원경에서 대기의 영향으로 인해 발생하는 오차를 실시간으로 보상해주는 적응 광학을 이용하면 지상용 망원경으로도 막대한 비용이 드는 우주용 망원경에 버금가는 이미지를 얻을 수 있다. 일반적으로 적응 광학계에서는 대기에 의한 파면 오차를 제거하기 위하여, 변형 거울을 변형시켜 각 부분의 파면 오차를 보정하는 방법을 이용하므로, 변형 거울을 효과적으로 변형시키기 위한 구동기의 특성과 구동기의 배열에 대한 연구가 필수적이다. 하나의 구동기론 작동하여 거울을 변형시킬 때, 변형된 거울면의 형태를 영향 함수라고 정의하며, 이러한 영향 함수를 이용하여 변형 거울을 효과적으로 모형화하고 설계할 수 있다. 본 논문에서는 유한요소해석을 이용하여 계산된 변형 거울의 실제 영향 함수를 가우시안 함수 형태로 단순화하고, 추가로 구동기들 사이의 영향을 고려한 커플링 계수를 도입하여, 주어진 구동기 배열에 대한 영향 함수를 결정하였다. 또한 변형 거울에 사용되는 구동기들 사이의 적절한 커플링 계수를 결정하기 위하여, 커플링 계수 변화에 따른 변형거울의 성능 변화를 해석하였다. 이와 같이 구성된 영향 함수를 이용하석, 구동기가 삼각형과 사각형 형태와 같이 등간격으로 배치되어 있을 때의 구동기 간격에 따른 변형 거울의 성능을 해석하고 효과적인 배열을 제안하였다.

• 로봇학회논문지
• /
• 제10권3호
• /
• pp.146-153
• /
• 2015

In order to contain as much information as possible in a single image, a wide FOV(Field-Of-View) imaging system is required. The catadioptric imaging system with hyperbolic cylinder mirror can acquire over 180 degree horizontal FOV realtime panorama image by using a conventional camera. Because the hyperbolic cylinder mirror has a curved surface in horizontal axis, the original image acquired from the imaging system has the geometrical distortion, which requires the image processing algorithm for reconstruction. In this paper, the image reconstruction algorithms for two cases are studied: (1) to obtain an image with uniform angular resolution and (2) to obtain horizontally rectilinear image. The image acquisition model of the hyperbolic cylinder mirror imaging system is analyzed by the geometrical optics and the image reconstruction algorithms are proposed based on the image acquisition model. To show the validity of the proposed algorithms, experiments are carried out and presented in this paper. The experimental results show that the reconstructed images have a uniform angular resolution and a rectilinear form in horizontal axis, which are natural to human.

• 천문학회보
• /
• 제43권2호
• /
• pp.55.4-56
• /
• 2018

Linear Astigmatism Free - Three Mirror System (LAF-TMS) is the linear astigmatism free off-axis wide field telescope with D = 150 mm, F/3.3, and $FOV=5.51^{\circ}{\times}4.13^{\circ}$. We report the design and analysis results of its mirrors and optomechanical structures. Tolerance allowance has been analyzed to the minimum mechanical tolerance of ${\pm}0.05mm$ that is reasonable tolerance for fabrication and optical alignment. The aluminum mirrors are designed with mounting flexure features for the strain-free mounting. From Finite Element Analysis (FEA) results of mounting torque and self-weight, we expect 33 - 80 nm RMS mirror surface deformations. Shims and the L-bracket are mounted between mirrors and the mirror mount for optical alignment. The mirror mount is designed with four light-weighted mechanical parts. It can stably and accurately fix mirrors, and it also suppresses some of stray light.

• 한국주조공학회지
• /
• 제14권6호
• /
• pp.558-565
• /
• 1994

The horizontal continuous casting process with the heated mold was applied to obtain the unidirectionally solidified rods($4{\sim}8mm$ dia.) of pure copper with good surface quality. The results could be summarized as follows. 1. The unidirectional solidification of pure copper rods with good surface(mirror surface) quality could be obtained by placing the S/L interface inside the heated mold cavity even though the cast copper rods were covered with thin copper oxide layer. 2. The casting speed for 4mm dia. rods with mirror surfaces was affected significantly by the mold-cooler distance rather than the cooling flow rate when other casting conditions were fixed. 3. The casting speed was the main factor affecting the oxidation of copper during the continuous casting and the thickness of copper oxide layer decreased almost linearly as the casting speed increased.

• 마이크로전자및패키징학회지
• /
• 제10권4호
• /
• pp.61-64
• /
• 2003

단일이온교환된 유리의 응력 특성을 관찰하기 위하여 파괴분석을 하였다. 프로세스변화로 인하여 이온교환된 유리의 응력층이 유리표면에서 안쪽으로 이동하였다. 깃털모양자국(hackle marker)과 거울면(mirror region)의 크기가 이온교환프로세스의 온도, 시간에 따라 변화하였으며, 파괴강도에 비례하였다. 또한 Indenter를 사용하여 응력층을 파괴하는 경우 일반유리와 같은 파괴특성을 나타냈다.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2004년도 추계학술대회 논문집
• /
• pp.97-100
• /
• 2004

In recent years, a demand for micro-structure machining is increasing by the development of information and optics industries. Micro machining technology is in general well known in the field of lithograghy. However, the requirement of producing micro machine and/or micro mechanism with metal materials will be increased since a variety of workpiece configurations can be easily made. In this paper, ultra precision machine is developed to obtain micro groove and mirror surface using single crystal diamond tool. According to the cutting experiment, no burr was found at the edge of V-grooves, and the surface roughness of copper is about 1～3nm Ra. It is verified that ultra precision machine is effective to high precision machining.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2003년도 추계학술대회 논문집 전기물성,응용부문
• /
• pp.49-52
• /
• 2003

Single crystalline silicon (SCS) was adopted for a reliable micromirror array of biochip fabrication applications. SCS has excellent mechanical properties and smooth surface, which is the best material for micromirror devices. The mirror array has $16{\times}16$ micromirrors and each mirror has a $120{\mu}m{\times}100{\mu}m$ reflective surface. The micromirror has simple torsional beam springs and electrostatic force was used for driving. The designed tilting angle was $9.6^{\circ}$, and the tilting angles were measured according to applied voltages. The surface roughness was measured by a laser profiler. The response time was measured using He-Ne laser and position sensitive diode (PSD), and the lifetime was checked for reliability proof.

• 대한기계학회논문집A
• /
• 제23권6호
• /
• pp.1011-1017
• /
• 1999

Electrolytic in-process dressing grinding technique which enables application of metal bond wheels with fine superabrasives in mirror surface grinding operations has developed. It is possible to make efficient precision machining of hard and brittle material such as ceramic and hard metal by the employment of this technique. However, in order to ensure the success of performances such as efficient machining, surface finish, and surface quality, it is important to sustain the insulating layer that has sharply exposed abrasives in wheel surface. Using AE(Acoustic Emission) sensor, this paper will show whether the insulating layer sustains stably or not in real grinding time. And by comparing AErms value and surface roughness their thresholds for stable electrolytic in-process dressing grinding will be determined.

• 한국정밀공학회지
• /
• 제19권10호
• /
• pp.195-201
• /
• 2002

This paper deals with the precision grinding for aspherical surface of optical parts. A parallel grinding method using the spherical wheel was suggested as a new grinding method. In this method, the wheel axis is positioned at a $\pi$/4 from the Z-axis in the direction of the X-axis. An advantage of this grinding method is that the wheel used in grinding achieves its maximum area, reducing wheel wear and improving the accuracy of the ground mirror surface. In addition, a truing by the CG (curve generating) method was proposed. After truing, the shape of spherical wheel transcribed on the carbon is measured by the Form-Talysurf-120L. The error of the form in the spherical wheel which is the value ${\Delta}x$ and $R{^2}{_y}$ inferred from the measured profile data is compensated by the re-truing. Finally, in the aspherical grinding experiment, the WC of the molding die was examined by the parallel grinding method using the resin bonded diamond wheel with a grain size of ＃3000. A form accuracy of 0.16${\mu}m$ P-V and a surface roughness of 0.0067${\mu}m$ Ra have been resulted.

• 기술사
• /
• 제27권3호
• /
• pp.59-64
• /
• 1994