• Current Optics and Photonics
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• v.6 no.4
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• pp.375-380
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• 2022

We demonstrate two types of light field displays based on waveguide grating coupler arrays: a line beam type and a point source type. Ultra violet imprinting of an array of diffractive nanograting cells on the top surface of a 50-㎛-thin slab waveguide can deliver a line beam or a point beam to a multidirectional light field out of the waveguide slab. By controlling the grating vectors of the nanograting cells, the waveguide modes are externally coupled to specific viewing angles to create a multidirectional light field display. Nanograting cells with periods of 300 nm-518 nm and slanted angles of -8.5°~+8.5° are fabricated by two-beam interference lithography on a 40 mm × 40 mm slab waveguide for seven different viewpoints. It is expected that it will be possible to realize a very thin and flexible panel that shows multidirectional light field images through the waveguide-type diffraction display.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.6
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• pp.654-662
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• 1988

A simple and useful model of light distribution for the biologhical tissue to the Gaussian beam is proposed. This model assumes that the incident Gaussian beam broadens into two Gaussian beams, travelling in the opposite directions as the result of both isotropic scattering and absorption in the tissue. With this assumption, two-dimensional light intensity of each flux as well as the equations of both absorption and scattering have been derived, and the validity of modeling has been confirmed experimentally. Consequently, the results paved a way for easy evaluation of the light distribution in the biological tissue.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.4
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• pp.371-379
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• 2015

This paper represents the structural design of the light weight axle beam for medium duty commercial vehicle using hot press. To reduce the weight of the axle, axle beam of solid type was replaced by hollow type which was made by hot press. According to the change of axle beam structure and manufacturing method, we have to investigate the structural strength and fatigue performance. To verify the axle beam performance, the structural analysis was carried out by simplified axle beam model and various design parameters that are axle beam height, thickness and width. From the analysis results, the light weight axle beam structure was founded and applied the full model analysis. This study will be used as a guidance in development of the light weight axle for medium duty commercial vehicle.

• 전기의세계
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• v.19 no.6
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• pp.8-12
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• 1970

A Device is described which intensity modulates a light beam at modulating frequency in the M/W region. A Method of designing a practical crystalline microwave-Freg. light modulator has been described. In addition, Electrooptic properties and operation as light modulator of NH$_{4}$H$_{2}$po$_{4}$ is described. A light path is provided through the crystal into a suitably oriented analyzer. The intensity of the light beam emerging from the latter varies at the same rate as the cavity frequency.

• Korean Journal of Optics and Photonics
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• v.15 no.2
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• pp.171-176
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• 2004

A light deflector integrated laser diode(LD) was fabricated and the characteristics of LD and ourput beam deflection as a function of deflector injection current were measured. To integrate the deflector with LD, a passive waveguide was integrated with the LD and a triangular-type light deflector was fabricated on the upper clad of the passive waveguide section. Light deflection from the fabricated light deflector is controlled by the effective refractive index variation induced by carrier injection. To characterize the effect of the deflector injection current, threshold current, slope efficiency, and output beam spectrum were measured as a function of deflector injection current. From these measured data, the increment in the threshold current and the decrement of the slope efficiency were observed. However, the output beam spectrum was not affected by the deflector. The Beam Propagation Method(BPM) was used to simulate the proposed device and the light deflection was measured by the far-field pattern of the output beam as a function of the deflector injection current. In the fabricated deflector integrated LD, the deflection angle of 1.9$^{\circ}$ at the injection current of 15 ㎃ was obtained.

• Transactions on Electrical and Electronic Materials
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• v.16 no.4
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• pp.201-205
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• 2015

This paper dealt with the condensing technology of an LED light source that uses a parabolic reflector to replace a searchlight equipped with a xenon lamp. A ray-tracing simulation was conducted to analyze the influence of the diameter of the reflector and the size of the light source on light condensing. The combination of a parabolic reflector with a diameter of 620 mm and a focal distance of 220 mm, and a 9 mm multi-chip package (MCP) with a luminous flux of 7,000 lm showed the narrowest beam angle. The luminous intensity at the center was measured at 7.7×10⁶ cd. The distance between the light source and the point where the illuminance was 1 lx was calculated to be 2.8 km. The power consumption of the system was 95 W, which is only 9.5% of that of the 1 kW xenon searchlight, and the beam angle was 1.03°. In a site experiment, it was confirmed that the light ray reflected from the LED searchlight proceeds forward without any diffusion because of the narrow beam angle.

• Laser Solutions
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• v.15 no.2
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• pp.11-14
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• 2012

In this paper, we have made a proposal concerning the beam shaping mask(BSM) using random-array slits to control intensity distribution profile of laser beam and demonstrated its proprieties experimentally. When a lot of slits are set out irregularly, diffraction patterns of light does not appear but granularity patterns as a bundle of fibers appear. Intensity distribution profile is controlled by densities distribution of circular slits arrayed randomly because the number of slits and its area means amount of light energy through BSM. Namely as the number of slits in high intensity area is increased and that in low intensity area decreased, amount of light energy is same over all local parts. So gaussian intensity distribution could be changed to flat-top.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.130-131
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• 2000

One of the more promising proposals for guiding and focusing neutral atoms involves dark hollow laser beams. When the frequency of the laser is detuned to the blue of resonance, the dipole force the atoms feel in the light confines them to the dark core where the atoms can be transported with minimal interaction with the light. The ability of the all-light atom guides to transport large number of ultracold atoms for long distances without physical walls leads to the possibility of a versatile tool for atom lithography, atom interferometry, atomic spectroscopy as well as for transporting and manipulating Bose-Einstein condensates. Furthermore since the atoms transported in all-light atom guides do not come into contact with matter, they can in principle be used to transport antimatter as well. The ability to vary the core size of the hollow beam makes the all-light atom guide potentially useful for focusing neutral atoms. The atoms could be focused as tight as the core size of the hollow beam at its waist. This new focusing scheme, called the atom funnel, would not show spherical and chromatic aberrations that conventional harmonic focusing suffers from. (omitted)

• Journal of the Korean Society of Visualization
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• v.18 no.1
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• pp.38-43
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• 2020

This paper presents a new type of electrowetting driven tandem light deflector for high performance optical application. To steer an incident light, the proposed light deflector deforms the fluid interface using electrowetting actuation. The performance of the light deflector was experimentally verified by using a prototype of the proposed light deflector. Single and tandem light deflectors were separately prepared using microfabrication processes. The optical tests of the deflectors were conducted using a laser light. The proposed tandem light deflector obtained a 45° beam steering angle with a 5.3° deflection angle while a single light deflector was required for a 10.9° deflection angle to obtain the same beam steering angle. The proposed tandem light deflector with high optical capability can be applied to various optical applications from camera modules in mobile smart devices to advanced future optical systems.

• Journal of Sensor Science and Technology
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• v.15 no.3
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• pp.186-191
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• 2006

In general, Cerenkov light is produced by a charged particle that passes through a medium with a velocity greater than that of visible light. Although the wavelength of Cerenkov light is very broad, the peak is in the almost visible range from 400 to 480 nm. Therefore, it always causes a problem to detect a real light signal that is generated in the scintillator on the fiber-optic sensor tip for dose measurements of high-energy electron beam. The objectives of this study are to measure, characterize and remove Cerenkov light generated in a fiber-optic radiation sensor tip to detect a real light signal from the scintillator. In this study, the intensity of Cerenkov light is measured and characterized as a function of incident angle of electron beam from a LINAC, and as a function of the energy of electron beam. As a measuring device, a photodiode-amplifier system is used, and a subtraction method using a background optical fiber is investigated to remove Cerenkov light.