• Journal of the Optical Society of Korea
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• v.9 no.2
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• pp.49-53
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• 2005

We report a new configuration of a reflection-type confocal scanning optical microscope system for measuring the refractive index profile of an optical waveguide. Several improvements on the earlier design are proposed; a light emitting diode (LED) at 650 nm wavelength instead of a laser diode (LD) or He-Ne laser is used as a light source for better index precision, and a simple longitudinal linear scanning and curve fitting techniques are adapted instead of a servo control for maintaining an optical confocal arrangement. We have obtained spatial resolution of 700 nm and an index precision of $2\times10^{-4}$. To verify the system's capability, the refractive index profiles of a conventional multimode fiber and a home-made four-mode fiber were examined with our proposed measurement method.

• Journal of the Optical Society of Korea
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• v.13 no.3
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• pp.341-348
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• 2009

We report the development of full-field swept-source optical coherence tomography (SS-OCT) in the wavelength range of 815-870 nm using a unique combination of super-luminescent diode (SLD) as broad-band light source and acousto-optic tunable filter (AOTF) as a frequency-scanning device. Some new applications of full-field SS-OCT in forensic sciences and engineering materials have been demonstrated. Results of simultaneous topography and tomography of latent fingerprints, silicon microelectronic circuits and composite materials are presented. The main advantages of the present system are completely non-mechanical scanning, wide-field, compact and low-cost.

• Journal of Information Display
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• v.11 no.1
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• pp.24-27
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• 2010

A novel stereo 3D LCD for passive interference filter glasses is presented. A demonstrator based on a standard 120Hz LCD was set up. Stereoscopic image separation was realized in a time-sequential mode using a LED-based scanning backlight with two complementary spectra. A stereo brightness of 3 cd/$m^2$ and a channel separation of 30:1 were achieved.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.127.4-127
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• 2001

Inspection and shape measurement of three-dimensional objects are widely needed in industries for quality monitoring and control. A number of visual or optical technologies have been successfully applied to measure three dimensional surfaces. Especially, the shape measurement using an interferometric principle becomes a successful methodology. However, those conventional interferometric methods to measure surface profile have an inherent shortcoming, namely 2∏ ambiguity problem. The problem inevitably happens when the object to be measured has discontinuous shape due to the repetition of interferometric signal with phase period of 2∏. Therefore, in this paper, we choose as a shape measuring method, ...

• 제어로봇시스템학회:학술대회논문집
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• 1986.10a
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• pp.145-148
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• 1986

To perform the marking on metal with high speed and non-contact using the laser beam of high energy, laser marking system is designed and fabricated applying the galvanometer scanner capable of high speed-precise beam positioning controlled by microprocessor. Laser is a Q-switched Nd:YAG producing multi-mode, wavelength, 1060nm. Optical system is composed of beam expander, scanning mirror and flat field lens. Consequently, the laser marking is satisfactorily achieved regardless of kinds of metal.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.246-249
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• 2009

A compact, flexible family of UV laser material processing systems has been developed to drive advancements in both large area processing and annealing of semiconductor surfaces. UV photons can either be applied via demagnifying a mask pattern image or by scanning a homogenized excimer beam across the substrate area. 193nm, 248nm and 308nm wavelength applications are supported.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.05a
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• pp.247-247
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• 2012

Gd-doped ZnO thin films were prepared with different growth temperatures by using a radio-frequency magnetron sputtering method. The deposited samples were characterized by using the X-ray diffractometer, the scanning electron microscopy, and the photoluminescence spectroscopy. All of the films show an average transmittance of about 85% in the wavelength range from 400 to 1100 nm.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.590-595
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• 2004

The shape and size variations of the nanopatterns produced on a positive photoresist using a near-field scanning optical microscope(NSOM) are investigated with respect to the process variables. A cantilever type nanoprobe having a 100nm aperture at the apex of the pyramidal tip is used with the NSOM and a He-Cd laser at a wavelength of 442nm as the illumination source. Patterning characteristics are examined for different laser beam power at the entrance side of the aperture( $P_{in}$ ), scan speed of the piezo stage(V), repeated scanning over the same pattern, and operation modes of the NSOM(DC and AC modes). The pattern size remained almost the same for equal linear energy density. Pattern size decreased for lower laser beam power and greater scan speed, leading to a minimum pattern width of around 50nm at $P_{in}$ =1.2$\mu$W and V=12$\mu$m/. Direct writing of an arbitrary pattern with a line width of about 150nm was demonstrated to verify the feasibility of this technique for nanomask fabrication. Application on high-density data storage using azopolymer is discussed at the end.

• Korean Journal of Optics and Photonics
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• v.13 no.2
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• pp.155-161
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• 2002

The nail bed is located under the finger nail. The arched portions of the nail bed, which contain a large number of capillary loops, are separated by the valley of the nail bed. The valley of the nail bed does not contain capillary loops. Light is scattered when it propagates through the dermis of skin, and human blood strongly absorbs the light with proper wavelength. By use of the optical properties of the nail bed, we propose an optical technique which extracts the nail bed image of the finger nail. After achieving nail bed images of each individual, we correlated between them. The correlation outputs show that we can identify individuals by comparing the peak heights of the correlation outputs.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.402.1-402.1
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• 2014

Photonic force microscopy (PFM) is an optical tweezers-based scanning probe microscopy, which measures the forces in the range of fN to pN. The low stiffness leads proper to measure single molecular interaction. We introduce a novel photonic force microscopy to stably map various chemical properties as well as topographic information, utilizing weak molecular bond between probe and object's surface. First, we installed stable optical tweezers instrument, where an IR laser with 1064 nm wavelength was used as trapping source to reduce damage to biological sample. To manipulate trapped material, electric driven two-axis mirrors were used for x, y directional probe scanning and a piezo stage for z directional probe scanning. For resolution test, probe scans with vertical direction repeatedly at the same lateral position, where the vertical resolution is ~25 nm. To obtain the topography of surface which is etched glass, trapped bead scans 3-dimensionally and measures the contact position in each cycle. To acquire the chemical mapping, we design the DNA oligonucleotide pairs combining as a zipping structure, where one is attached at the surface of bead and other is arranged on surface. We measured the rupture force of molecular bonding to investigate chemical properties on the surface with various loading rate. We expect this system can realize a high-resolution multi-functional imaging technique able to acquire topographic map of objects and to distinguish difference of chemical properties between these objects simultaneously.