• Title/Summary/Keyword: Telecentric system

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Optical Design of an Image-space Telecentric Two-mirror System for Wide-field Line Imaging

  • Lee, Jong-Ung;Kim, Youngsoo;Kim, Seo Hyun;Kim, Yeonsoo;Kim, Hyunsook
    • Current Optics and Photonics
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    • v.1 no.4
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    • pp.344-350
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    • 2017
  • We present a new design approach and an example design for an image-space telecentric two-mirror system that has a fast f-number and a wide-field line image. The initial design of the telecentric mirror system is a conventional axially symmetric system, consisting of a flat primary mirror with fourth-order aspheric deformation and an oblate ellipsoidal secondary mirror to correct spherical aberration, coma, and field curvature. Even though in the optimized design the primary mirror is tilted, to avoid ray obstruction by the secondary mirror, the image-space telecentric two-mirror system shows quite good imaging performance, for a line imager.

Development of Image-space Telecentric Lens for Intra-Oral 3D Scanner

  • Kim, Tae Young;Shin, Min-Ho;Chang, Ryungkee;Kim, Young-Joo
    • Journal of the Optical Society of Korea
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    • v.19 no.3
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    • pp.303-310
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    • 2015
  • An image-space telecentric lens for an intra-oral 3D scanner was designed and fabricated for dental application. Since a telecentric function can provide the same results regardless of image plane position, it helps to realize a more accurate image for an intra-oral scanner. The performance of the designed lens meets the required properties for HD resolution. In particular, lateral color is corrected within 1 pixel. This system achieves depth of focus of more than 3 mm. For user convenience, the developed system consists of a prism part and an imaging part. Both parts are optimized to reduce the front size and weight of the system. In order to make the parallax sights, parallax angle was determined to be 8 degrees between two optical systems.

Design of a Telecentric Lens with a Smartphone Camera to Utilize Machine Vision (머신비전을 위한 스마트폰용 텔레센트릭 렌즈의 설계)

  • Choi, Yeon-Chan;Rim, Cheon-Seog
    • Korean Journal of Optics and Photonics
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    • v.29 no.4
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    • pp.149-158
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    • 2018
  • A generalized structural design equation can be used to simplify and systematize a telecentric lens system composed of multiple lenses, as a creative design method of the authors. Through this structural equation, we have investigated the feasibility and design methodology of a telecentric lens equipped with a conventional smartphone camera for machine vision. As a result, we could verify and present a useful, generalized structural equation termed the $f{\theta}$ formula, being able to divide and combine the whole telecentric lens system into two modularized lens groups.

A conceptual introduction and the research of the optical properties of the Telecentric lens system (Telecentric 렌즈계의 이해와 광학적 성능 조사)

  • Kim, Bonghwan;Lim, Hyeonseon;Ji, Taeksang;Yoon, Sungro
    • Journal of Korean Ophthalmic Optics Society
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    • v.7 no.2
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    • pp.197-202
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    • 2002
  • In this paper, we want to help understanding about telecentric as introducing the concept of the system and researching the optical properties after we choose the designed profile projection lens. An analyzed optical system is F-number=2.8 and the first lens is used negative lens. Accordingly, we can know this system is compacter, because the front focal position is to the inside of the system and aperture stop is designed to the inside of the optical system. The field is about $21^{\circ}$. Since the entrance pupil is located the front focal point, we can certify the exit pupil is -49404.1mm, located on the infinite toward the object space. Therefore, the optical system is the form of 'image space telecentricity'.

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Development of a Measuring Instrument for the Coefficient of Luminous Intensity of Retro-Reflection of Miniature Telecentric Cameras (소형 텔레센트릭 카메라 광학계의 재귀반사 측정 방법 연구 및 측정 장치 개발)

  • Yeo, TaeWoon;Karasik, V.E.;Kim, Young Il
    • Korean Journal of Optics and Photonics
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    • v.25 no.6
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    • pp.334-339
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    • 2014
  • In this paper, the optical properties of a miniature telecentric camera are studied analytically and experimentally. By means of optical properties, the luminous intensity of retro-reflection of a miniature telecentric optical system is investigated. First, from a simulation the theoretical value of the coefficient of luminous intensity of retro-reflection of a miniature telecentric system is estimated. Second, a miniature telecentric camera device is designed, and the value of the coefficient of luminous intensity of retro-reflection of the actual device is measured through experiment. From simulation and experiment, we found that both the estimated and observed values of the coefficient of luminous intensity of retro-reflection range from 0.002 to $0.03m^2/sr$ (P384200CPH: $0.0042-0.018m^2/sr$, P285200CPH: $0.0045-0.0297m^2/sr$, P321450S: $0.0021-0.00963m^2/sr$) at 1.4 to 4.9 arcminute. The results prove the significance of the mechanisms used to design the miniature telecentric camera, and the experimental method. Accordingly, with these significant results, this study contributes to the development of theory and practice in optical engineering science.

Development of 3D scanner using structured light module based on variable focus lens

  • Kim, Kyu-Ha;Lee, Sang-Hyun
    • International Journal of Advanced Culture Technology
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    • v.8 no.3
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    • pp.260-268
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    • 2020
  • Currently, it is usually a 3D scanner processing method as a laser method. However, the laser method has a disadvantage of slow scanning speed and poor precision. Although optical scanners are used as a method to compensate for these shortcomings, optical scanners are closely related to the distance and precision of the object, and have the disadvantage of being expensive. In this paper, 3D scanner using variable focus lens-based structured light module with improved measurement precision was designed to be high performance, low price, and usable in industrial fields. To this end, designed a telecentric optical system based on a variable focus lens and connected to the telecentric mechanism of the step motor and lens to adjust the focus of the variable lens. Designed a connection structure with optimized scalability of hardware circuits that configures a stepper motor to form a system with a built-in processor. In addition, by applying an algorithm that can simultaneously acquire high-resolution texture image and depth information and apply image synthesis technology and GPU-based high-speed structured light processing technology, it is also stable for changes to external light. We will designed and implemented for further improving high measurement precision.

Novel Telecentric Collimator Design for Mobile Optical Inspection Instruments

  • Hojong Choi;Seongil Cho;Jaemyung Ryu
    • Current Optics and Photonics
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    • v.7 no.3
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    • pp.263-272
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    • 2023
  • A collimator refers to an optical system that images a collimated beam at a desired point. A resolution target located at a near distance can be converted into a virtual image located at a long distance. To test the resolution for mobile cameras, a large target is placed at a long distance. If a collimator system is used, the target can be placed at a near distance. The space required for a resolution inspection can thus be drastically reduced. However, to inspect a mobile camera, the exit pupil of the collimator system and the entrance pupil of the mobile camera must match, and the stop of the collimator system must be located on the last surface. Because a collimator system cannot be symmetrical with respect to the stop, the distortion becomes extremely large, which can be corrected by combining the collimator symmetrically with respect to the object plane. A novel system was designed to inspect an optical lens on a mobile phone. After arranging the refractive power, lenses were added using the equivalent lens design method. The distortion was reduced to less than 1%. This optical system satisfies a half-field angle of 45° and an optical performance sufficient for inspection.

Four-mirror optical system for UV submicron lithography (서브미크론 리소그라피를 이한 4 반사광학계의 설계)

  • 박성찬
    • Proceedings of the Optical Society of Korea Conference
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    • 1991.06a
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    • pp.81-87
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    • 1991
  • A design of a four-mirror optical system for submicron lithography using KrF excimer laser beam(λ=248nm) is presented. By using the third order aberration theory, analytic solutions for a telecentric, flat-field, and anastigmatic four-spherical-mirror system (reduction magnification 5$\times$) are found. Aspherization is carried out to the spherical mirror surfaces in order to reduce the residual higher order aberrations and vignetting effect. Finally we obtain a reflection system useful in submicron lithographic application.

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Design of a Tele-centric Wide Field Lens with High Relative Illumination and Low Distortion Using Third-order Aberration Analysis

  • Kim, Kae-Hong;Kim, Yeong-Sik;Park, Sung-Chan
    • Journal of the Optical Society of Korea
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    • v.19 no.6
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    • pp.679-686
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    • 2015
  • This paper presents a design method for improving the low relative illumination and large distortion due to widening the field of a system. A tele-centric optical system in image space was suggested to increase the relative illumination. Through the analyses of the third-order aberrations affected by introducing aspherical surfaces, we have proposed a method to determine analytically what surface should be aspheric to correct each aberration effectively. By utilizing this method to design a wide field lens, a tele-centric wide field lens with f-number of F/2.0 was obtained. Even though the field angle is 120 degrees, it has a very low distortion less than -2% and high relative illumination more than 73.7%. In conclusion, this analytic method for selecting aspherical surfaces is expected to serve as a useful way to find design solutions.