• Medical Lasers
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• v.10 no.3
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• pp.123-131
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• 2021

Optical imaging modalities with properties of real-time, non-invasive, in vivo, and high resolution for image-guided surgery have been widely studied. In this review, we introduce two optical imaging systems, that could be the core of image-guided surgery and introduce the system configuration, implementation, and operation methods. First, we introduce the optical coherence tomography (OCT) system implemented by our research group. This system is implemented based on a swept-source, and the system has an axial resolution of 11 ㎛ and a lateral resolution of 22 ㎛. Second, we introduce a fluorescence imaging system. The fluorescence imaging system was implemented based on the absorption and fluorescence wavelength of indocyanine green (ICG), with a light-emitting diode (LED) light source. To confirm the performance of the two imaging systems, human malignant melanoma cells were injected into BALB/c nude mice to create a xenograft model and using this, OCT images of cancer and pathological slide images were compared. In addition, in a mouse model, an intravenous injection of indocyanine green was used with a fluorescence imaging system to detect real-time images moving along blood vessels and to detect sentinel lymph nodes, which could be very important for cancer staging. Finally, polarization-sensitive OCT to find the boundaries of cancer in real-time and real-time image-guided surgery using a developed contrast agent and fluorescence imaging system were introduced.

• Journal of Sensor Science and Technology
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• v.25 no.4
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• pp.280-284
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• 2016

For an arc-flash protection system, the selection of arc-flash sensor in implementation is largely dependent on the coverage area and the spatial resolution. Typically, a point sensor is used to accurately measure an arc event within a very narrow region; whereas, a loop or a line sensor can cover several electrical compartment at the same time, but with a poor resolution. In this work, a novel scheme for an arc-flash sensor was developed by making use of the transmission loss of plastic optical fibers (POFs) to cover a broad range with a high spatial resolution. By relating the amplitude ratio of the arc-signals at the ends of the POF with the arc-location, arc events could be located with a resolution of ~5 cm within a spatial range of 10 m, which has not been reported yet.

• Journal of the Optical Society of Korea
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• v.11 no.1
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• pp.18-25
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• 2007

We present an ultrahigh-resolution full-field optical coherence tomography (FF-OCT) implemented with a white-light interference microscope and a detector array as an alternative OCT technique. The use of detector array allows the capture of two-dimensional en-face images in parallel without taking any lateral scanning process. The phase shifting interferometric technique with the sinusoidal phase modulation (SPM) is utilized to get the demodulated OCT images. The configuration of the system and the resolution of the obtained image are presented. The topographic images, taken with the implemented system, of a coin, an integrated circuit chip, and the tomographic images of an onion epithelium are demonstrated also. Axial and lateral spatial resolution of ${\sim}1.0{\mu}m$ and ${\sim}2.0{\mu}m$ are achieved with the system respectively.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.6
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• pp.31-36
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• 2004

Optical coherence tomography system has been extensively studied because it has some advantages such as imaging of high resolution, low cost, and compact size configuration. In order to obtain high resolution of OCT system we configured OCT system using a femto-second laser. We measure the pulse width using autocorrelator function because a femto-second laser is ultra short pulse. And we measured the practical resolution using theoretical equation and the measurement of reference sample. It is confirmed that the proposed OCT system has 1.5 times higher resolution and un distinctive cross-sectional image than OCT system with SLD as a light source.

• Journal of the Institute of Convergence Signal Processing
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• v.2 no.3
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• pp.86-92
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• 2001

Position controls are very important in semiconductor manufacturing devices, machine tools, precision measuring instruments, etc. to measure the distance of movement of moving objects in minute units and the accuracy of measurement for the moving distance in these devices affect the performance of the whole devices. Therefore, in those precision instruments, a sensing device that can measure the distance of movement with high-precision resolution is required. Thus an optical encoder that has such advantages as easy digital interface, economical price, and a resolution similar to that of laser interferometers can be used. In this paper, a interferometer-type linear scale with easy digital interface and high-resolution has been set up and measured the distance of movement based on the diffraction principle. Interference signals produced in this optical setup of the linear scale have beers digitalized through fabricated photodetectors and designed signal processing circuits. A resolution of 0.5${\mu}{\textrm}{m}$ is acquired from the experimental interferometer-type linear scale without for the movement of scales any additional dividing circuits. It is shown that from this experiment a high-resolution distance measurement device can be designed by a simple optical setup.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.5
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• pp.120-124
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• 2017

The temporal super resolution is a method for increasing the frame rate. Electro-optical sensors are used in various surveillance and reconnaissance weapons systems, and the spatial resolution and temporal resolution of the required electro-optical sensors vary according to the performance requirement of each weapon system. Because most image sensors capture images at 30~60 frames/second, it is necessary to increase the frame rate when the target moves and changes rapidly. This paper proposes a method to increase the frame rate using color channel extrapolation. Using a DMD, one frame of a general camera was adjusted to have different consecutive exposure times for each channel, and the captured image was converted to a single channel image with an increased frame rate. Using the optical flow method, a virtual channel image was generated for each channel, and a single channel image with an increased frame rate was converted to a color channel image. The performance of the proposed temporal super resolution method was confirmed by the simulation.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.23 no.1
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• pp.49-57
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• 2005

The proposed algorithm is to achieve the robust optical flow detection which is applicable for the case that the outlier rate is over 80%. If the outlier rate of optical flows is over 30%, the discrimination between the inliers and outlier with the conventional algorithm is very difficult. The proposed algorithm is to overcome such difficulty with three steps of grouping algorithm; 1) constructing the 2D histogram with two axies of the lengths and the directions of optical flows. 2) sorting the number of optical flows in each bin of the two-dimensional histogram in the descending order and removing some bins with lower number of optical flows than threshold. 3) increasing the resolution of the two-dimensional histogram if the number of optical flows in a specific bin is over 20% and decreasing the resolution if the number of optical flows is less than 10%. Such processing is repeated until the number of optical flows falls into the range of 10%-20% in all the bins. The proposed algorithm works well on the different kinds of images with many of wrong optical flows. Experimental results are included.

• Journal of the Optical Society of Korea
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• v.19 no.6
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• pp.695-699
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• 2015

A high spectral resolution lidar (HSRL) system based on injection-seeded Nd:YAG laser and iodine absorption filter has been developed for the quantitative measurement of aerosol and cloud. The laser frequency is stabilized at 80 MHz by a frequency locking system and the absorption line of iodine cell is selected at the 1111 line with 2 GHz width. The observations show that the HSRL can provide vertical profiles of particle extinction coefficient, backscattering coefficient and lidar ratio for cloud and aerosol up to 12 km altitude, simultaneously. For the measured cases, the lidar ratios are 10~20 sr for cloud, 28~37 sr for dust, and 58~70 sr for urban pollution aerosol. It reveals the potential of HSRL to distinguish the type of aerosol and cloud. Time series measurements are given and demonstrate that the HSRL has ability to continuously observe the aerosol and cloud for day and night.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.12
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• pp.15-21
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• 2010

Recently, there is a demand for a thermal imaging microscope in the medical field as well as the semi-conductor industry Although the demand of the advanced thermal imaging microscope has been increased, it is very difficult to obtain the technology of developing a thermal camera, because it is used for defense industry. We developed the ${\times}5$ zoom microscope which has $3\;{\mu}m$ spatial resolution to research the design and fabrication of the IR (Infrared) optical system. The optical system of the IR microscope consists of four spherical lenses and four aspheric lenses. We verified individual sensitivity of each optical parameter as the first order approach to the analysis. And we also performed structure and vibration analysis. The optical elements are fabricated using Freeform 700A. The measurement results of surface roughness and form accuracy using NT 2000 and UA3P are Ra 2.36 nm and P-V $0.13\;{\mu}m$. Finally we ascertained resolution power of $3\;{\mu}m$ using USAF (United State Air Force) 1951 IR resolution test chart.

• Proceedings of the Membrane Society of Korea Conference
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• 2003.07a
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• pp.61-64
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• 2003

Optical resolution of a-amino acid (tryptophan and tyrosine) optical isomers was achieved by a pressure driven membrane separation process, using self-supporting crosslinked membranes base on polysaccharide with different swelling indices that ranged from 100 to 70%. The membranes prepared by casting and drying the polymer solution containing 5wt% acetic acid on an acryl plate followed by crosslinking with glutaraldehyde were characterized using such analytical methods as FTIR and swelling index measurements. On the way of separating the optical isomers, several experimental factors such as the concentration of the feed solutions, operating pressure and temperature, and degree of crosslinking of the membranes have been studied. When the chitosan membranes with 70% of swelling index were used , almost complete optical resolution was obtained; 97.92% of enantiomeric excess (ee %) and 2.26 g/$m^2$ㆍh of flux. The operating pressure and the concentration of feed solutions were respectively 1.0 kgf/$\textrm{cm}^2$ and 0.49 mmol/L.