• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 1999.11a
• /
• pp.240-246
• /
• 1999

The determination of surface topography is believed to be extremely important in the areas of contact mechanics, adhesion and friction. In order to describe topography of various frictional surface, the wear test was carried out under different experimental conditions in dry friction. And fractal descriptors was applied to frictional surface of laser modified steel with image processing system. These descriptors to analyze surface structure are fractal dimension. Surface fractal dimension can be determined by sum of intensity difference of surface pixel. Topography of frictional surface can be effectively obtained by fractal dimensions.

• Journal of the Korean Society for Precision Engineering
• /
• v.16 no.10
• /
• pp.203-208
• /
• 1999

By tilting the reference mirror of Twynman-Green interferometer having a reference mirror and a moving mirror, firinge pattern composed of bright and dark parallel lines can be obtained and the fringe pattern is shifted according to the displacement of the mowing mirror. Several studies are executed for displacement measurement by detecting the intensity of the fringe with photo-diodes having small detecting area. In this study, to improve the sensitivity and robustness, the intensity of fringe is detected by using a large-area quadratic photo-diode masked with a grating panel having four kinds of binary grating having phase-difference of 0, {\pi}$/4, {\pi}$/2, 3 {\pi}$/4. The phase of the fringe is calculated with a simple 4-buckets algorithm. A experimental result shows that standard deviation of 5.653 nm is obtained comparing with a capacitive type gap sensor having nearly 1 nm accuracy.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.08a
• /
• pp.107-107
• /
• 2010

In this study, we have investigated the holographic grating formation on Ag-doped amorphous chalcogenide AsGeSeS thin films with Ag thickness. Ag/AsGeSeS thin films with the incident laser beam wavelength for the improvement of the polarization diffraction grating efficiency. Holographic gratings have been formed using Diode Pumped Solid State laser (DPSS, 532.0nm) under [P:P] polarized the intensity polarization holography. The diffraction efficiency was obtained by +1st order intensity. The result is shown that the diffraction efficiency of Ag/AsGeSeS double layer thin film for the Ag thickness, the maximum grating diffraction efficiency using 60nm Ag layer is 0.96%.

• Journal of the Optical Society of Korea
• /
• v.9 no.2
• /
• pp.45-48
• /
• 2005

We investigate effects of the injected ASE (Amplified spontaneous emission) bandwidth on the performance of the wavelength-locked Fabry-Perot laser diodes (F-P LDs) under constant injection power density and constant injection power. For the constant injection power density, we can determine the minimum injection bandwidth by the required intensity noise or the bit-error rate (BER) performance. On the other hand, there exists the optimal ASE bandwidth for the constant injection power to minimize the intensity noise.

• Korean Journal of Optics and Photonics
• /
• v.4 no.4
• /
• pp.493-495
• /
• 1993

The frequency of the 633 nm internal mirror He-Ne laser has been stabilized by using the beat frequency and the intensity difference between two Zeeman split components in a transverse magnetic field. The frequency stability and the frequency temperature coefficient for the beat frequency method was $7.0{\times}10^{-11}$ and $170 kHz/^{\circ}C$, respectively, and those for the intensity difference was $1.1{\times}10^{-9}$ and $1.8 MHz/^{\circ}C$, respectively.

• Journal of the Optical Society of Korea
• /
• v.18 no.5
• /
• pp.611-615
• /
• 2014

We report high-speed pulse train generation from a relatively low-speed 10-GHz mode-locked laser by means of line-by-line spectral coding. To increase the pulse repetition rate multiplication (RRM) factor, we combine coding schemes for both spectral intensity and phase by placing a simple mask at the coder focal plane. The resulting RRM factor, determined by multiplying the RRM factors of the individual coding schemes, rises as high as 16. To verify the generated pulses, the optical spectra and autocorrelation traces are examined.

• Journal of IKEEE
• /
• v.16 no.4
• /
• pp.364-368
• /
• 2012

We generate 10 GHz short pulses from a continuous wave laser at 1.5 um by cascaded intensity and phase modulation, followed by chirp compensation using a single mode fiber. The measured spectral and pulse widths are 0.64 nm and 5.7 ps respectively, resulting in the time-bandwidth product of 0.46.

• Korean Journal of Optics and Photonics
• /
• v.12 no.6
• /
• pp.496-502
• /
• 2001

We generated a nondiffracting beam and investigated its intensity profile on propagation. We first obtained an annular output beam from Nd:YAG laser with a negative branch unstable ring resonator and, using a 1m focal length lens, we generated a Bessel- Gauss beam. The inner radius of the annular output beam was 2.57 mm and the ring width was 0.145 mm. The intensity profile of the nondiffracting beam did not show any appreciable diffraction up to 33 m distance from the focal lens. This result was compared with the theory.

• Journal of Sensor Science and Technology
• /
• v.24 no.2
• /
• pp.93-95
• /
• 2015

We present an optical detection method for the fundamental vibrational mode of a tuning fork crystal oscillator in air. A focused He/Ne laser beam is directed onto the edge of one vibrating tine of the tuning fork; its vibrating motion chops the incoming laser beam and modulates the intensity. The beam with modulated intensity is then detected and converted to an electrical signal by a high-speed photo-detector. This electrical signal is a sinusoid at the resonant frequency of the tuning fork vibration, which is 32.76 kHz. Our scheme is robust enough that the sinusoidal signal is detectable at up to $40^{\circ}$ of rotation of the tuning fork.

• Korean Journal of Optics and Photonics
• /
• v.2 no.3
• /
• pp.133-138
• /
• 1991

Eosin-doped boric acid glass saturable absorber has a relatively low saturation intensity (700 mW/$\textrm{cm}^2$) and low power optical phase conjugation is achived by the degenerate four-wave mixing (DFWM) experiments. Polarization properties of optical phase conjugation by DFWM have been demonstrated in this materials using a cw argon ion laser at wavelength 488 nm. The dependence of the phase conjugated reflectivity on the intensity and wavelength of the pump beam is examined. The magnitude of the energy exchange by the nondegenerate two-wave mixing (NDTWM) is maximized by frequency difference between the two beams of $\varphi\simeq$ 1100 Hz.