• Journal of the Optical Society of Korea
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• v.1 no.2
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• pp.74-80
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• 1997

300mm F/4.0 telephotolens with diffractive hybrid lens was designed, and its optical performance was tested and compared with a traditional lens system. DOE(Diffractive Optical Element) reconstructs wavefronts using wave phenomena of light to focus the incident light onto the focal point and has negative Abbe number while a traditional lens uses geometrical phenomena of light and has positive Abbe number. Therefore, a diffractive hybrid lens containing both refractive and diffractive elements can remarkably correct chromatic aberration and spherical aberration of an optical system. We investigated and analyzed the optical properties of a diffractive hybrid lens for the visible spectrum, and we used a difractive hybrid lens to design and evaluate a 300mm F/4.0 telephotolens without the special LD(Low Dispersive) glass lens which is costly and difficult to manufacture. Most traditional telephotolenses use the special LD glass for chromatic aberration correcton. Optical performance tests such as resolution and characteristics of aberration of both lens systems using a diffractive hybrid lens and traditional lens were performed.

• Journal of the Optical Society of Korea
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• v.19 no.4
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• pp.421-426
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• 2015

This paper presents a hybrid single optical system for an LED surgical light that combines the advantages of both lens- and reflector-type single optical systems. The proposed hybrid single optical system includes a lens in the center and the LED light originating from the lens is redirected using a reflector to achieve a high beam spread. Iterative optical software simulations are used to provide data for the design of the lens and reflector for a single optical system, and for a complex optical system for the LED light assembly. The resulting data is also used to fabricate a prototype system. Experiments using the prototype of the hybrid single optical system and a mock-up LED surgical light confirm the system's shadow dilution performance and its applicability to surgical operations.

• Korean Journal of Optics and Photonics
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• v.19 no.5
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• pp.349-359
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• 2008

For an inner-focusing 3-groups zoom lens system, this study suggests a new initial design method which applies the process that changes thin lenses into thick ones effectively and quickly, using the hybrid lens system(thin lens+thick lens). In other words, the hybrid lens system is the semi-automatic design process that makes the thin lens of one group change into a thick one while the other groups are composed of thin lenses. Keeping the total power of the system fixed, the power of each group and the distance between principal planes can be fixed. Of course, the other groups composed of thin lenses could be changed into thick lenses sequentially by this process. This design conception results in the 1/4" 5 M inner-focusing 3-groups 2x zoom lens system satisfying the specifications and performances of zoom lens for phone cameras. Also aspherization on lens elements of glass and plastic material enhanced the resolution and reduced the lens size. As a result, we have an ultra-compact inner-focusing 3-groups 2x zoom lens system for a phone camera, with a slim size with TTL of 9.8 mm.

• Korean Journal of Optics and Photonics
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• v.31 no.2
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• pp.96-104
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• 2020

A catadioptric omnidirectional zoom optical system using a hybrid lens (COZOSH) that performs simultaneously two functions of a lens and a mirror was designed at the visible wavelength range for daytime unmanned surveillance, and its performance was analyzed. The hybrid lens has lots of advantages in terms of fabrication and assembly of a COZOSH, because of the obviation of a lens boring process and reduction of the number of optical components. Additionally, we designed the COZOSH to expand the compressed inner-image region of a donut image at low spatial frequencies. As a result, the optimized design performance of the optical system that satisfies all initial design specifications was obtained from calculation of the modulation transfer function, spot diagram, and tolerance analysis. We confirmed that the COZOSH is a passively athermalized optical system under conditions of temperature variation from -30℃ to 50℃, by using athermalization analysis during zooming.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.05a
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• pp.123-126
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• 2005

Eye Glass Display (EGD) with microdisplay to realize the virtual display can make the large screen, so virtual image has been developed by using microdisplay panel. This paper shows study of low cost lens design and simulation for microdisplay system with 0.6"LCoS panel. Lens design optimized consider to spherical aberration, astigmatism, distortion, and chromatic aberration. Code V is used and it designed an aspheric lens about exit pupil 6mm, eye relief 20mm and 35 degree of field of view (FOV). With the application this aspheric lens to liquid crystal on silicon (LCOS) type's microdisplay, virtual image showed 50 inch at 2m. One side of the aspheric lens was constituted from diffractive optical element (DOE) for the improvement in a performance. It had less than 2.5% of distortion value and modulation transfer function in axial had 20% of resolution with 32 lp/mm spatial frequency. The optical system is suitable for display of 15.6 mm-diagonal with SVGA.

• Korean Journal of Optics and Photonics
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• v.11 no.4
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• pp.239-245
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• 2000

In this paper, the fundamental properties of diffractive optical element were investigated. Also, this work deals with theoretical approaches for achromatization in DOE's optical system based on thin lens theory. It is found that achromatization could be satisfied by one hybrid lens only, which is composed of a diffractive and a refractive element. In order to have compact optical system, we used the tele-photo type lens composed of a positive and a negative power elements instead of retro-focus lens. From the Gaussian brackets and Seidel aberration theory, the initial design was numerically obtained. The aberration properties of an initial design was aplanat and flat field. In order to correct the chromatic aberrations, refractive and diffractive elements were used on front element. This hybrid lens is also useful for correction of higher order aberrations. Compared to conventional design composed of refractive lenses only, this approach dramatically improved the compactness of the optical system. Finally, residual aberration balancing results in a lens with focal length of 3.89 mm and overall length of 5.19 mm, which has enough performance over an f-number of 4.0. Also, it is expected to fulfill all the requirements of a digital still camera lens. This optical system is superior to the current refractive lens system in the number of elements, weight, and aberration properties. rties.

• Current Optics and Photonics
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• v.4 no.5
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• pp.441-445
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• 2020

A novel design for a Fresnel lens for a solar end-pumped laser is demonstrated in this paper. The new hybrid Fresnel lens includes two parts, inner and outer. The inner part is a twice-total-internal-reflection and vertical-transmission lens. The outer part is a once-total-reflection and vertical-transmission lens. The radius of the Fresnel lens is 600 mm, and its focal length is 750 mm. The concentrating performance of the Fresnel lens is examined using TracePro. The results show that the concentration efficiency has been greatly improved. The total concentration efficiency of the hybrid Fresnel lens reaches 73.2% when the radius of the laser rod is 3 mm. This design can simplify the concentration system of a solar end-pumped solid-state laser.

• Korean Journal of Optics and Photonics
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• v.14 no.3
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• pp.236-243
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• 2003

We discussed the design of lens module schematic eyes equivalent to finite model eyes, which are used to model the human eye based on spherical aberration and Stiles-Crowford effect. The optical system for head mounted display (HMD) is designed and evaluated using lens module schematic eyes. In addition to a compact HMD system, an optical system with high Performance is required. To satisfy these requirements, we used diffractive optical elements and aspheric surfaces so that the color and mono-chromatic aberrations were corrected. The optical system for HMD is composed of 0.47 inch micro-display of SVGA grade with 480,000 pixels, a plastic hybrid lens for the virtual image, and the lens module schematic eyes. The designed optical system fulfills the current specifications of HMD: such as, EFL of 31.25 mm, FOV of 24H$\times$18V$\times$30D degrees, and overall length of 59.1 mm. As a result, we could design an optical system useful for HMD; the system is expected to be comfortable while the user wears it.

• The Journal of Korea Robotics Society
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• v.6 no.3
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• pp.210-219
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• 2011

This paper studies how to combine devices such as monocular/stereo cameras, motors for panning/tilting, fisheye lens and convex mirrors, in order to solve vision-based robotic problems. To overcome the well-known trade-offs between optical properties, we present two mixed versions of the new systems. The first system is the robot photographer with a conventional pan/tilt perspective camera and fisheye lens. The second system is the omnidirectional detector for a complete 360-degree field-of-view surveillance system. We build an original device that combines a stereo-catadioptric camera and a pan/tilt stereo-perspective camera, and also apply it in the real environment. Compared to the previous systems, we show benefits of two proposed systems in aspects of maintaining both high-speed and high resolution with collaborative moving cameras and having enormous search space with hybrid configuration. The experimental results are provided to show the effectiveness of the mixing collaborative and hybrid systems.

• Korean Journal of Optics and Photonics
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• v.28 no.5
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• pp.241-249
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• 2017

This paper presents the design and evaluation of the optical system for an uncooled thermal-imaging camera. The operating wavelength range of this system is from $7.7{\mu}m$ to $12.8{\mu}m$. Through optimization, we have obtained a LWIR (Long Wave Infrared) optical system with a focal length of 5.44 mm, which consists of four aspheric surfaces and two diffractive surfaces. The f-number of the optical system is F/1.2, and its field of view is $90^{\circ}{\times}67.5^{\circ}$. The hybrid lens was used to balance the higher-order aberrations, and its diffraction properties were evaluated by scalar diffraction theory. We calculated the polychromatic integrated diffraction efficiency, and the MTF drop generated by background noise. We have evaluated the thermal compensation of a LWIR fixed optical system, which is optically passively athermalized to maintain MTF performance in the focal depth. In conclusion, these design results are useful for an uncooled thermal-imaging camera.