• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.5 s.108
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• pp.483-489
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• 2006

In this paper, new wideband lens amplifiers are proposed for C-band wireless communication service. In order to obtain the wideband property, all components of the proposed lens amplifiers are designed with balanced structure and wideband characteristics. Fat dipole antenna as the input and output antenna, balanced amplifier as amplifying components, and coplanar stripline(CPS) as the delay line fer the beam focusing are used fur composing the stable wideband lens amplifier. The $5{\times}5$ 2D lens amplifier has the characteristics that the absolute gain is 7.5 dB, the EIPG is 37.4 dB at 6 GHz, and the 3-dB gain bandwidth is 19.8 %.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.6
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• pp.8-14
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• 2006

The object transport system is used in many industry field such as the conveyor belt, which transports huge goods in container harbor, the magnetic levitation system, and the indexing system which transports precision components such as semiconductor and optical components. In conventional transport system, the magnetic field may damage semiconductor and the contact force may scratch on the optical lens. So ultrasonic wave transport system has been proposed to replace the previous transport system. In this paper, the good transport condition of optical lens is obtained according to the flexural beam shapes. The working frequency and transport speed are measured and the vibration characteristics of the flexural beams are investigated by Laser Scanning Vibrometer.

• Korean Journal of Optics and Photonics
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• v.5 no.1
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• pp.166-172
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• 1994

The fiber optic receiver, ETRI APD-FET 1.0, is developed for the application of optical communication. This fiber optic receiver includes PD sub-module and pre-amplifier case. A single lens system is introduced for the PD sub-module. The sub-module consists of the avalenche photodiode(APD), GRIN rod lens, and a single mode fiber. The above components are enclosed into the stainless steel 304L housings. By bevelling the fiber end, the single mode fiber provides less than ~ 28 dB of optical return loss. The area of image focus is controlled by adjusting the length of spacer located in-between the fiber and the GRIN rod lens. The laser welding technique is applied to achieve the maximum coupling efficiency for the joining of each housing. In the pre-amplifier case, GaAs FET pre-amplifier workes for photocurrent amplification and the thermister is mounted to control the APD bias. The performance of ETRI APD-FET1.0 shows the sensitivity of - 30.3 dBm at $10^{-10}$ BER(bit error rate) and 2.5 Gbps optical random signal of $2^{23}-1$ word length. The fiber optic receiver is one of the essensial parts of the transmission module for B-ISDN. Also, the above optical packaging technology will be adapted for the developement of 10 Gbps transmission application 2.5 Gbps 5 Gbps

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.6
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• pp.143-150
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• 2004

In this paper, resonant ultrasound spectroscopy(RUS) was used to determine the natural frequency of a ceramic ferrule and a ball lens. The ceramic ferrules are cylinderical shape with $\phi$ 2.56mm diameter and l0mm in length. Crack lengths of these ferrules are 10.40$\mu$m, 21.18$\mu$m and 32.35$\mu$m. The spherical ball lens was made of BK-7 glass, one's diameter in 2mm and 5mm. RUS system is consisted of spectrum analyzer, power amplifier, PZT sensor and support frame. The principle of RUS is that the mechanical resonant frequency of the materials depends on density and the coefficient of elasticity. Rus system is based on that given resonant frequency of the materials can be represented by the function of density and the coefficient of elasticity, and it is applied to excite specimen and to inspect the difference of natural frequency pattern between acceptable specimen and defective ones. Defect evaluation by RUS are performed to investigate the natural frequency measure of ferrule and ball lens.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.6
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• pp.1133-1138
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• 2010

We have developed an imaging radiometer system at W-band. The system consists of lens, reflector, 30-ch receiver array, scanner, and signal processor. One receiver consists of a dielectric rod antenna, a balun, LNA(low noise amplifier) and a detector. The system configuration requirements are described. Finally, we represent radiometer images to obtain through clouds, smoke, dust, and other obstructions which render visible and IR systems ineffective.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.4
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• pp.471-477
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• 2014

Purpose: We have analyzed the transmittance distribution of the ocular lens using local transmittance microscope to investigate the optical homogeneity of the lens. Methods: The transmittance of the laser which is focused on the surface of the ocular lens was measured by using the photo-detector and lock-in amplifier and analyzed. Multi-coated, uncoated, and progressive lenses were analyzed. Results: In the measurement of the progressive lens and a physical stimulated lens, local transmittance microscopy analysis showed a high degree of match with the measurement results through the optical microscope. In addition, the average value of the transmittance is reduced and the standard deviation was increased in the presence of optical defects. In unstimulated lens, there are a large impact on transmittance whether the anti-reflective coating is presence or absence in both the local transmittance microscopy and general transmittance analysis. Conclusions: The distribution of the transmittance measured by local transmission microscopy were changed when the various stimulus is applied to the lenses. These analyzes by local transmission microscopy can be utilized as a way to evaluate or determine the uniformity of the coating film or lens.

• Korean Journal of Optics and Photonics
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• v.7 no.1
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• pp.1-8
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• 1996

Charge-coupled device(CCD) array detectors are widely used in real time modulation transfer function(MTF) measurement systems. This paper presents the characteristics of two-dimensional CCDs used in a real time MTF measurement system for copy lenses. The MTF characteristics of a copy lens measured by this equipment show different results according to the direction of shift register, shutter speed and the amplifier gain of CCDs. An object generator is fabricated to reduce the variation of MTF values for the irradiance nonuniformity in on-axis and off-axis image plane and this MTF equipment is calibrated by using a standard lens.

• Korean Journal of Optics and Photonics
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• v.17 no.6
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• pp.556-563
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• 2006

We present a comprehensive study of a chirped pulse Ti:sapphire regenerative amplifier system operating at 1 kHz. Main constituents of the system are described in detail. The amplifier stage was first converted to a repetition rate-tunable kHz gain-switched nanosecond Ti:sapphire laser. Operation characteristics at different repetition rates such as build-up times of laser pulses, pump power-dependent output powers and pulse durations, damage thresholds, and tunability ranges were studied. Based on the results achieved, the switching time of the Pocket's cell used and the round trip numbers in the regenerative amplifier were optimized at 1 kHz. The output pulses with a pulse width of 50fs from a home-made Ken lens mode-locked Ti:sapphire oscillator were used as seed pulses. The pulses were expanded to 120ps in a grating stretcher prior to coupling into the 3-mirror amplifier cavity. After amplification and recompression, a stable 1kHz Ti:sapphire regenerative amplifier system, which delivers 85-fs, $320-{\mu}J$ pulses, was fully constructed.

• Journal of Korean Ophthalmic Optics Society
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• v.20 no.4
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• pp.471-476
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• 2015

Purpose: We have analyzed the transmittance distribution of various ocular lenses using local transmittance microscope to investigate the optical homogeneity of the lens. Methods: The local transmittance of the laser which is focused on the surface of the spectacle lens was measured by using the photo-detector, lock-in amplifier and motorized-stage. 25 multi-coated lenses with non-tinted of 5 groups and 45 multicoated lenses with tinted of 9 groups were analyzed as a sample respectively. Results: Average and deviation of local transmittance for nontinted lenses were measured almost uniformly with various refractive index and coating. However, deviation of transmittance of for tinted lenses was analyzed as about 3.7 times larger than that of non-tinted lenses. Inhomogeneity of local transmittance of for tinted lenses was also analyzed as about 3.1 times larger than that of non-tinted lenses. Conclusions: We could analyze that standard deviation of transmittance and inhomogeneity of local transmittance of for tinted lenses is larger than that of non-tinted lenses using the local transmittance microscope. These analysis using local transmittance microscope can be utilized as a way to evaluate lens performance and improve optical homogeneity.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.7
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• pp.577-583
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• 2014

In this study, we introduce how to apply "Information and Communication Technology (ICT) to injection molding system. We report the current state of IT technology applied to produce their products in micro lens injection molding system. And we explain key technology of ICT for injection molding system and how to implement. Especially, we also mention about an embedded controller, also called as "M2M device". It provides programmable intelligent functions, communication, various interfaces, amplifier functions and mobile device connection to our application.