• Title/Summary/Keyword: 대물

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Design of 4:1 I$\mathbb{R}$ zoom afocal telescope (원적외선 대역 4 : 1 줌 망원경 광학계 설계)

  • 김현숙;김창우;홍석민
    • Korean Journal of Optics and Photonics
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    • v.9 no.3
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    • pp.134-141
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    • 1998
  • A high performance afocal zoom telescope has been designed to operate in the 7.6${\mu}{\textrm}{m}$ to 10.3${\mu}{\textrm}{m}$ waveband for thermal imaging system. This IR zoom telescope is characterized by using of two movable optical element groups, variator and compensator, with mechanically compensated method and the positioning of these groups is controlled by means of a computerized program. The optical performance over the entire 4:1 zoom range and $\pm$2.31~$\pm$9.36 degrees field of view is near diffraction limit while maintaining a constant F-number. The all refracting surfaces of this system except only one aspheric surface are spherical curvature and the material for the optical elements is selected Ge and ZnSe which is used for correction of chromatic aberration.

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Gaussian Bracket Expressions of Aplanatic and Achromatic Conditions for Telephoto Type Telescope Objective Derived from the Numerical Solution (Aplanat조건과 Achromatwhrjs의 Gauss괄호 표현과 Telephoto형 망언경 대물렌즈의 설계)

  • 임천석
    • Korean Journal of Optics and Photonics
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    • v.4 no.3
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    • pp.243-251
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    • 1993
  • We have derived Gaussian bracket expressions of aplanatic and achromatic conditions and obtained the numerical solutions for each of two modules of the telephoto type telescope objective free from the Seidel first order spherical aberration, coma, and longitudinal chromatic aberration. The system which is for use in sighting a target is optimized within the resolution of eyes. The objective lens satisfying the aplanatic and achromatic condition has f/8.5 with the half field angle 0.$3^{\circ}$, and the telephoto ratio is 0.839 with the focal length of 30 cm.

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Twin-Image Elimination in In-line Digital Holography Microscope (In-line 디지털 홀로그래피 현미경에서 쌍둥이 상 제거연구)

  • Cho, Hyung-Jun;Yu, Young-Hun
    • Korean Journal of Optics and Photonics
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    • v.18 no.2
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    • pp.117-121
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    • 2007
  • A fundamental problem in the in-line digital holography microscope is that the real image and virtual image and zero-order image are not separated spatially. In this paper, we have eliminated the zero-order noise by an averaging method and the twin image is divided using a geometrical set-up in an in-line digital holographic microscope. The size of the virtual image depends on the distance between the objective lens and the hologram plane and on the distance between the hologram plane and the image plane. We found that the virtual image size is smallest when the distance between the objective lens and the hologram plane is equal to the back focal length of the objective lens. We could divide the virtual image and real image by controlling the distance between the hologram plane and the objective lens.

Optical Design of a Lister Objective Stable Against Chromatic Variation for 405-nm Wavelength (파장 405 nm에서 파장변화에 안정화된 Lister 대물렌즈 설계)

  • Kim, Jin-Hyung;Lee, Jong-Ung
    • Korean Journal of Optics and Photonics
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    • v.31 no.6
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    • pp.295-303
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    • 2020
  • A Lister objective of NA 0.25 and 10×, stabilized against chromatic variation for a wavelength of 405 nm is designed. We develop a new solution for stabilizing a cemented doublet that has specified axial thicknesses. Using the new method, we can easily obtain a useful design for some practical purpose. At the initial design stage, two cemented doublets corrected independently are used. The stabilizing conditions for the whole system are maintained during optimization. The final design of the Lister objective shows that the chromatic variation of EFL, BFL, and RMS wavefront errors are very small at the 405-nm wavelength, as expected.

Optical Design of Gradient-Index Objective for Optical Pickup (광 Pickup 용 Gradient-Index 대물렌즈 설계)

  • Park, In-Kyu;Lee, Jong-Ung
    • Korean Journal of Optics and Photonics
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    • v.18 no.4
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    • pp.256-263
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    • 2007
  • High NA objective design by using SELFOC materials was studied, and two kinds of objective for optical pick-up were designed. The SELFOC materials have radial gradient index distribution, and it gives additional degree of freedom in optical design. Therefore, we expect that optical design of high NA objective without aspheric surface will be possible. In this study, the variation of ms spot diameter was investigated as a function of quadratic constant and refractive index on axis for various combinations of axial thickness and entrance pupil diameter. For the survey, Code V was used for optimization and evaluation of the objective lenses. The result suggested that larger quadratic constant and higher refractive index on axis could give us better imaging performance for all combinations of axial thickness and pupil diameter. Based on the survey, we designed high NA objectives for DVR. There were two kinds of design solution consisting two spherical SELFOC lenses. The solution I had positive-positive lens configuration with short over-all-length, but it had poor off-axial performance compared with the solution II. The solution II had negative-positive lens configuration with good off-axial imaging performance. But the solution II had some disadvantages, long over-all-length and large diameter of the second lens.

Effect of Particle Contamination on Objective Lens in a CD-ROM Drive on Laser Diode Power and Photo Diode RF Signal (CD-ROM 드라이브의 대물렌즈 입자오염이 Laser Diode의 Power와 Photo Diode의 RF Signal에 미치는 영향)

  • Pae, Yang-Il;Hwang, Jung-Ho
    • Proceedings of the KSME Conference
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    • 2003.04a
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    • pp.1429-1434
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    • 2003
  • A number of dust particles are intruded into ODD(Optical disk drive) due to the flow caused by disk rotation and are adhered to a lens or disk surface. The space between the disk and the lens is being reduced. Someone indicates the problems of this drive that are relatively small data storing capacity and slow access time. In recent, the problems of this optical disk drive mentioned above are being solved by adding the speed of the disk's revolution, making the actuator high-speed or light, and making the beam spot size smaller than making the space narrow between disk and lens. These particle contamination affects seriously RF Signal, readout signal in an ODD. Especially, the affected parts by a particle contamination in an ODD's readout signal are objective lens and media.

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