• Journal of the Optical Society of Korea
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• 제17권6호
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• pp.518-524
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• 2013

This study presents a new design method for a zoom lens, in which real lens groups are designed successively to combine to form a lens modules zoom system. The lens modules and aberrations are applied to the initial design for a four-group inner-focus zoom system. An initial design with a focal length range of 4.2 to 39.9 mm is derived by assigning the first-order quantities and third-order aberrations to each module along with the constraints required for optimum solutions. After obtaining the lens module zoom system, the real lens groups are successively, not separately, designed to get a zoom lens system. Compared to the separately designed real lens groups, this approach can give a better starting zoom lens and save time. The successively designed groups result in a zoom system that satisfies the basic properties of the zoom system consisting of the original lens modules. In order to have a slim system, we directly inserted the right-angle prism in front of the first group. This configuration resulted in a compact zoom system with a depth of 12 mm. The finally designed zoom lens has an f-number of 3.5 to 4.5 and is expected to fulfill the requirements for a mobile zoom camera having high zoom ratio of 10x.

• Journal of the Optical Society of Korea
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• 제20권2호
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• pp.283-290
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• 2016

This study presents an 8x four-group inner-focus zoom lens with one-moving group for a compact camera by use of a focus tunable lens (FTL). In the initial design stage, we obtained the powers of lens groups by paraxial design based on thin lens theory, and then set up the zoom system composed of four lens modules. Instead of numerically analytic analysis for the zoom locus, we suggest simple analysis for that using lens modules optimized. After replacing four groups with equivalent thick lens modules, the power of the fourth group, which includes a focus tunable lens, is designed to be changed to fix the image plane at all positions. From this design process, we can realize an 8x four-group zoom system having one moving group by employing a focus tunable lens. The final designed zoom lens has focal lengths of 4 mm to 32 mm and apertures of F/3.5 to F/4.5 at wide and tele positions, respectively.

• Journal of the Optical Society of Korea
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• 제13권2호
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• pp.206-212
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• 2009

This study presents the compact zoom lens with a zoom ratio of 5x for a mobile camera by using a prism. The lens modules and aberrations are applied to the initial design for a four-group inner-focus zoom system. An initial design with a focal length range of 4.4 to 22.0 mm is derived by assigning the first-order quantities and third-order aberrations to each module along with the constraints required for optimum solutions. We separately designed a real lens for each group and then combined them to establish an actual zoom system. The combination of the separately designed groups results in a system that satisfies the basic properties of the zoom system consisting of the original lens modules. In order to have a slim system, we directly inserted the right-angle prism in front of the first group. This configuration resulted in a more compact zoom system with a depth of 8 mm. The finally designed zoom lens has an f-number of 3.5 to 4.5 and is expected to fulfill the requirements for a slim mobile zoom camera having high zoom ratio of 5x.

• Current Optics and Photonics
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• 제6권1호
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• pp.104-113
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• 2022

We present a method to count the overall length of the zoom system in an initial design stage. In a zoom-lens design using the concept of the group, it has been very hard to precisely estimate the overall length at all zoom positions through the previous paraxial studies. To solve this difficulty, we introduce T_eq as a measure of the total track length in an equivalent zoom system, which can be found from the first order parameters obtained by solving the zoom equations. Among many solutions, the parameters that provide the smallest T_eq are selected to construct a compact initial zoom system. Also, to obtain an 8× four-group zoom system without moving groups, tunable polymer lenses (TPLs) have been introduced as a variator and a compensator. The final designed zoom lens has a short overall length of 29.99 mm, even over a wide focal-length range of 4-31 mm, and an f-number of F/3.5 at wide to F/4.5 at tele position, respectively.

• Journal of the Optical Society of Korea
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• 제19권6호
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• pp.629-637
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• 2015

Compact system cameras (CSCs) are commonly used nowadays and feature enhanced video functions and thin yet light interchangeable lenses. They differ from digital single-lens reflex (DSLR) cameras in their lack of mirror boxes. CSCs, however, have autofocus (AF) speeds lower than those of conventional DSLRs, requiring weight reduction of their AF groups. To ensure the marketability of large telephoto zoom lenses with fixed f/2.8 regardless of field angle variation, in particular, light weight AF groups are essential. In this paper, we introduce a paraxial optical design method and present a new, large, telephoto zoom lens with f/2.8 regardless of the field angle variation, plus a lightweight AF group consisting of only one lens. Using the basic paraxial optical design and optimization methods, we fabricated a new and lighter zoom lens system, including a single-lens, lightweight AF group with almost the same performance.

• Journal of the Optical Society of Korea
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• 제18권2호
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• pp.134-145
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• 2014

The number of lens groups in modern zoom camera systems is increased above that of conventional systems in order to improve the speed of the auto focus with the high quality image. As a result, it is difficult to calculate zoom loci using the conventional analytic method, and even the recent one-step advanced numerical calculation method is not optimal because of the time-consuming problem generated by the iteration method. In this paper, in order to solve this problem, we suggest a new unified analytic method for zoom lens loci with finite object distance including infinite object distance. This method is induced by systematically analyzing various distances between the object and other groups including the first lens group, for various situations corresponding to zooming equations of the finite lens systems after using a spline interpolation for each lens group. And we confirm the justification of the new method by using various zoom lens examples. By using this method, we can easily and quickly obtain the zoom lens loci not only without any calculation process of iteration but also without any limit on the group number and the object distance in every zoom lens system.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
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• pp.213-216
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• 2005

A novel hyperspectral imaging spectrometer controlling spatial and spectral resolution individually has been proposed. This imaging spectrometer uses a zoom lens as a telescope and a focusing element. It can change the spatial resolution fixing the spectral resolution or the spectral resolution fixing the spatial resolution. Here, we report the concept of the hyperspectral imaging spectrometer with the novel zooming function and the optical design of a zoom lens as the focusing element. By using lens module and third-order aberration theory, we have presented the initial design of four-group zoom lens with external entrance pupil. And the optimized zoom lens with a focal length of 50 to 150 mm is obtained from the initial design by the optical design software. As a result, the designed zoom lens shows satisfactory performances in wavelength range of 450 to 900 nm as a focusing element in an imaging spectrometer. Furthermore, the collimator lens of the imaging spectrometer is designed through the third-order aberration correction by using an iterative process.

• 한국광학회지
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• 제16권1호
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• pp.34-42
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• 2005

본 논문은 3군 구성의 줌 광학계에 대해 렌즈모듈의 개념을 이용하여 1차량 및 3차 수차를 고려한 최적의 초기설계와 이로부터 실제 줌 광학계를 설계하는 방법을 제안 하였다. 각각의 렌즈모듈에 적절히 1차량과 3차 수차량을 설정함으로써 줌비 2배(f = 4.3∼8.6 mm)를 갖고, 시스템에서 요구하는 구속조건을 만족시키는 초기설계 줌 광학계를 얻었다. 각 군의 역할에 따라 적절히 선정된 각각의 렌즈군의 초점거리 및 1차량이 렌즈모듈의 값과 같도록 독립적으로 설계한 후, 군사이의 공기간격을 조정하므로써 줌궤적을 일치시켰다. 이러한 과정을 통해 설계된 줌 광학계는 렌즈모듈로 구성된 원래의 초기 설계된 줌 광학계와 동일한 1차 특성을 갖는다. 결과적으로 잔여수차 보정을 통해 후군초점조절방식을 이용하는 컴팩트 디지털 카메라 및 모바일 폰용 줌 렌즈로서 유용한 줌 광학계를 얻을 수 있었다.

• 한국안광학회지
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• 제7권2호
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• pp.113-121
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• 2002

요즈음 개발되는 각종 카메라, 캠코더, CCTV, 복사기 등의 광학계는 줌과 비구면을 이용하여 작으면서도 광각과 망원을 동시에 수용하고 성능도 우수하다. 본 논문에서는 사진기에 이용되는 2군 줌 렌즈계(비구면 사용)와 3군 줌 렌즈계의 성능을 분석, 평가한 것들을 참고로 하여 사진기용 3군 줌 렌즈계도 설계하였다. 설계한 사진기용 줌 렌즈계는 3군으로 하고 비구면을 도입함으로써 성능향상과 소형화를 도모하였다. 설계결과는 광학계 평가 도구인 유한광선수차, MTF, Seidel 수차 계수 등을 이용하여 참고 모델과 비교하였으며 거의 비슷한 수준이 유지됨을 확인하였다.

• 한국광학회지
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• 제8권2호
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• pp.81-87
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• 1997

본 논문은 4군구성의 비디오 카메라용 줌광학계에 대해 렌즈모듈의 개념을 이용하여 1차량 및 3차 수차를 고려한 최적의 초기설계와 이로부터 설계 줌광학계를 설계하는 방법을 제안하였다. 최적화 과정을 통해 각각의 렌즈모듈에 적절히 1차량과 3차 수차량을 설정함으로써 줌비 10배(f'=6.1693~58.4065)를 갖고, 최적설계에 필요한 구속조건을 만족시키는 초기설계 줌광학계를 얻었다. 적절히 선정된 각각의 렌즈군의 촛점거리가 렌즈모듈의 촛점거리와 같도록 scaling 한 후, 군사이의 공기간격을 조정하므로써 줌궤적을 일치시켰다. 이러한 과정을 통해 독립적으로 설계된 군들을 결합시켜 얻은 줌광학계는 렌즈모듈로 구성된 원래의 초기설계된 줌광학계와 동일한 1차특성을 갖는다. 결과적으로 잔여수차 보정을 통해 후군촛점조절방식을 이용하는 비디오 카메라 줌렌즈로서 유용한 줌광학계를 얻을 수 있었다.