• Journal of the Optical Society of Korea
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• v.18 no.1
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• pp.23-31
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• 2014

Recently, the number of camera companies that produce commercializing interchangeable lens systems such as digital single lens reflex (DSLR) and compact system camera (CSC) lenses has been gradually increasing. These interchangeable lenses have various kinds of lenses with distinct specifications. In particular, the distance window among these specifications is the function most preferred by customers. Mechanical manual zoom and manual focus in these high end camera lenses with a distance window are in particular desirable specifications and are required for product quality. However, the AF lens group is linked to the zoom cam and moves. Because the AF lens group moves along with the object distance, we can not realize the distance window with only zoom locus calculation. In this paper, in order to solve the problem, we suggest an optical calculation method for a corrected AF zoom cam for an interchangeable lens with a distance window to achieve product differentiation and analyze the error in the calculation.

• Korean Journal of Optics and Photonics
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• v.20 no.3
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• pp.156-165
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• 2009

We theoretically derive the set of general paraxial zoom locus equations for all zoom lens systems with finite object distance, including the infinite object distance case, by using the Gaussian bracket method and matrix representation of paraxial ray tracing. We make the zoom locus program by means of a numerical calculation method according to these equations in Visual Basic Language. Consequently, the solutions of this method can be consistently and flexibly used in all types of zoom lens in the step of initial design about zoom loci. Finally, in order to verify the justification and usefulness of this method, we show that two examples, such as $M_{4a}$ and $M_{4h}$ types of 4 groups, and one example, $M_{5n}$ type of 5 groups, which are very complicated zoom lens systems, can be rapidly and diversely traced through various interpolations by using this program.

• Korean Journal of Optics and Photonics
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• v.16 no.1
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• pp.34-42
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• 2005

This paper presents the optimum initial design containing the first and third order properties of the three-group zoom system using lens modules, and the real lens design of the system. The optimum initial design with focal length range of 4.3 mm to 8.6 mm is derived by assigning appropriate first and third order quantities to each module along with the specific constraints required for the system. An initial real lens selected for each group has been designed to match its focal length and the first orders into those of the each lens modules, and then combined to establish an actual zoom system by adjusting the air space between the groups at all zoom positions. The combination of the separately designed groups results in a system which satisfies the first order properties of the zoom system composed of the original lens modules. As a result, by residual aberration correction, we could obtain a zoom system useful in compact digital zoom cameras and mobile phone cameras employing the rear focus method.

• Journal of Korean Ophthalmic Optics Society
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• v.7 no.2
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• pp.113-121
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• 2002

Nowadays, developed camera, camcorder, CCTV and copier system accept a wide angle and a telephoto lens, and have an excellent capacity. Also, it is small as using aspheric surface. In this paper, after we evaluate and analyze two-group zoom lens system and three-group zoom lens system for camera, we refer to it, and design three-group zoom lens system for camera. Therefore, when we design a zoom lens system for camera, we use a symmetrical system. As using an aspheric surface, we can try to a miniaturization and an efficient improvement. We use optical valuable measure methods, a ray intercept plot, MTF and Seidel coefficient. So, we can confirm to have a similar level to compare with reference model.

• Journal of Korean Ophthalmic Optics Society
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• v.5 no.2
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• pp.119-125
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• 2000

We analyzed to calculate optical capacity after we chose established 2 component zoom copier lens system in this research. As the lens system is zoom lens system of finite object point, it has moving area limited not like to use generally camera zoom lens of infinite object point because it moves between object and image plane. The magnification of optical system can obtain -1.41~-0.64 i.e., extended or shortened image as transverse magnification, and it acquires f/12 and about $20^{\circ}$ field of view. Although this 2 component zoom copier lens system will be down resolution and dark compared with f/2.8 acquired at camera lens, it will be possibile to be able to make large aperture and it can acquire more better correct aberration with the addition of auxiliary group forward or backward.

• Proceedings of the KSRS Conference
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• 2005.10a
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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.

• Korean Journal of Optics and Photonics
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• v.33 no.6
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• pp.287-294
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• 2022

This study presents a method for designing an athermal middle wavelength infrared (MWIR) zoom lens with the iterative selection of material compositions on an athermal glass map. The optical properties of glass for MWIR are generally very sensitive to temperature, compared with visible glass. To compensate for focus error due to temperature change, the non-athermalized zoom system requires a large amount of movement of a compensator, which results in an unstable zoom system. To solve this problem, the material compositions for an athermal zoom lens have effectively been obtained using the thermal aberration correction process analytically on an athermal glass map. An expander lens is used to enlarge the focal lengths of an original main zoom lens two times. Finally, while this expander is attached to an original athermal zoom system, the final zoom system equipped with this expander doubles the focal length ranges and has stable performance over a specified temperature range.

• Korean Journal of Optics and Photonics
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• v.8 no.2
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• pp.81-87
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• 1997

This paper presents the optimum initial design containing the first and third order properties of the four-group video camera zoom system using lens modules, and its real lens design. The optimum initial design with focal length range of 6.1693 to 58.4065 mm is derived by assigning appropriate first order quantities and third order aberrations to each module along with the specific constraints required for optimization. By scaling the focal length of each lens group, an initial real lens selected for each group has been designed to match its focal length into that of the each lens module, and then combined to establish an actual zoom system by adjusting the air space between the groups at all zoom positions. The combination of the separately designed groups results in a system which satisfies the first order properties of the zoom system consisting of original lens modules. As a result, by residual aberration correction, we could obtain a zoom system useful in video zoom camera employing the rear focus method.

• Journal of Korean Ophthalmic Optics Society
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• v.6 no.1
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• pp.93-100
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• 2001

We analyzed aspheric patterns after we investigated zoom lens' constructions and optical capacities of a ordinary designed 35mm camera with an aspheric zoom lens system in this research. As this lens system was the zoom lens system about infinite object point, it was made to get a short back focal length, be able to use a lens unit more close to the image plane, and be used the compact camera which got a viewing system. The zoom ratio of the system was 1 : 2 and it got a positive and negative power's distribution. As it was determined the 35~70 mm focal length range which the most common people used, it might be called economic optical system considered universality. As it was used two aspheric surface, it was used just three lens, compensated the aberration and schemed lens' miniaturization, lightweightization, and the decrease effect of the unit cost of production.

• Journal of Korean Ophthalmic Optics Society
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• v.6 no.2
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• pp.1-9
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• 2001

This research chose the existing designed copier zoom lens system and analyzed to calculate the optical capacity. As this lens system was the zoom lens system of finite object point, differed form the general camera zoom lens of infinite object point, it got a limited movement range because it moved between the fixed object and the image. In the result of comparison the optical capacities between a symmetric form and a asymmetric form. We could find out the truth which a asymmetric form constituted comparative stable aberrations and existed a tracks of effort for aberration correction. Therefore, a symmetric form is allotted satisfactorily from improved aberrations by itself in the fixed focal lens system. However, it has a limit of improving for capacity when it is used a zoom lens system got a symmetric form.