• Current Optics and Photonics
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• v.7 no.5
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• pp.537-544
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• 2023

Differential phase contrast (DPC) microscopy, a central quantitative phase imaging (QPI) technique in cell biology, facilitates label-free, real-time monitoring of intrinsic optical phase variations in biological samples. The existing DPC imaging theory, while important for QPI, is grounded in paraxial diffraction theory. However, this theory lacks accuracy when applied to high numerical aperture (NA) systems that are vital for high-resolution cellular studies. To tackle this limitation, we have, for the first time, formulated a nonparaxial DPC imaging equation with a transmission cross-coefficient (TCC) for high NA DPC microscopy. Our theoretical framework incorporates the apodization of the high NA objective lens, nonparaxial light propagation, and the angular distribution of source intensity or detector sensitivity. Thus, our TCC model deviates significantly from traditional paraxial TCCs, influenced by both NA and the angular variation of illumination or detection. Our nonparaxial imaging theory could enhance phase retrieval accuracy in QPI based on high NA DPC imaging.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1358-1361
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• 2008

Several different techniques currently exist for measuring display view angle performance. These include conoscopes, goniometric systems, and, most recently introduced to the market, instruments based on Imaging Sphere technology. This paper will compare measurement accuracy and speed of these various methodologies with different FPD types and even 3-D displays.

• Nuclear Medicine and Molecular Imaging
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• v.43 no.3
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• pp.229-239
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• 2009

Molecular imaging strives to visualize processes in living subjects at the molecular level. Monitoring biochemical processes at this level will allow us to directly track biological processes and signaling events that lead to pathophysiological abnormalities, and help make personalized medicine a reality by allowing evaluation of therapeutic efficacies on an individual basis. Although most molecular imaging techniques emerged from the field of oncology, they have now gradually gained acceptance by the cardiovascular community. Hence, the availability of dedicated high-resolution small animal imaging systems and specific targeting imaging probes is now enhancing our understanding of cardiovascular diseases and expediting the development of newer therapies. Examples include imaging approaches to evaluate and track the progress of recent genetic and cellular therapies for treatment of myocardial ischemia. Other areas include in vivo monitoring of such key molecular processes as angiogenesis and apoptosis, Cardiovascular molecular imaging is already an important research tool in preclinical experiments. The challenge that lies ahead is to implement these techniques into the clinics so that they may help fulfill the promise of molecular therapies and personalized medicine, as well as to resolve disappointments and controversies surrounding the field.

• Journal of Chest Surgery
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• v.52 no.4
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• pp.205-220
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• 2019

Near-infrared (NIR) fluorescence imaging provides a safe and cost-efficient method for immediate data acquisition and visualization of tissues, with technical advantages including minimal autofluorescence, reduced photon absorption, and low scattering in tissue. In this review, we introduce recent advances in NIR fluorescence imaging systems for thoracic surgery that improve the identification of vital tissues and facilitate the resection of tumorous tissues. When coupled with appropriate NIR fluorophores, NIR fluorescence imaging may transform current intraoperative thoracic surgery methods by enhancing the precision of surgical procedures and augmenting postoperative outcomes through improvements in diagnostic accuracy and reductions in the remission rate.

• Investigative Magnetic Resonance Imaging
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• v.25 no.4
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• pp.218-228
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• 2021

Due to their high degree of freedom to transfer and acquire light, fiber optics can be used in the presence of strong magnetic fields. Hence, optical sensing and imaging based on fiber optics can be integrated with magnetic resonance imaging (MRI) diagnostic systems to acquire valuable information on biological tissues and organs based on a magnetic field. In this article, we explored the combination of MRI and optical sensing/imaging techniques by classifying them into the following topics: 1) functional near-infrared spectroscopy with functional MRI for brain studies and brain disease diagnoses, 2) integration of fiber-optic molecular imaging and optogenetic stimulation with MRI, and 3) optical therapeutic applications with an MRI guidance system. Through these investigations, we believe that a combination of MRI and optical sensing/imaging techniques can be employed as both research methods for multidisciplinary studies and clinical diagnostic/therapeutic devices.

• Journal of the Korean Graphic Arts Communication Society
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• v.20 no.1
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• pp.133-145
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• 2002

A study on electronic imaging system with silver halide photography emulation by a parametric approach will be introduced. The study contains the comparison analysis between silver halide imaging process and electronic imaging process, the characterization of the detailed process in those imaging chains, such as exposure, developing, photographic print and the other photographic and digital process. We investigated the characteristic curve between optical density and the amount of exposure in silver halide and digital photography systems. Under wide range of exposure condition, several sensitometric parameters were obtained via studio and outdoor photographic experiments with conventional photography and a digital camera. whose experimental results will be shown. Finally, the comparison between electronic imaging and conventional photography via silver halide photography emulation and modeling the silver halide process wi13 be discussed.

• Korean Journal of Optics and Photonics
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• v.12 no.4
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• pp.281-288
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• 2001

In this study we carried out athermalization analysis and tests to meet the required optical performance for thennal imaging systems even if the systems were operating over a wide temperature range. By using optical design programs such as Code- V and SIGMA2100, the simulation for athermalization was done with FPA thermal imaging system. In the athermalization test putting the thermal imaging system and collimator into a temperature chamber, the images depending on the temperature were recorded on video tape. In particular, the zoom thermal imaging system with two dimensional array detector was tested to check the result of the athermalization simulation. As a result, it was proved to meet the required optical performance for the thermal imaging system within $-32-+50^{\circ}C$ temperature range. range.

• Transactions of the Society of Information Storage Systems
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• v.9 no.1
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• pp.17-21
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• 2013

Optical coherence tomography (OCT) allows non-invasive, cross-sectional optical imaging of biological tissue with high spatial resolution and acquisition speed. In principle, it is analogous to ultrasound imaging, but uses near-infrared light instead of ultrasound, measuring the time-delay of back-scattered light from within biological tissue. Compared to ultrasound imaging, it exhibits superior spatial resolution (1~10 um) and high sensitivity. Therefore, OCT has been applied to a wide range of applications such as cellular imaging, ophthalmology and cardiology. Here, we describe a novel application of OCT technology in visualizing microneedles embedded in tissue that is developed to deliver drugs into the dermis without the injection mark in the human skin. Detailed three-dimensional structural images of microneedles and biological tissues were obtained. Examining structural modification of microneedles and tissues during insertion process would enable to evaluate performance of various types of microneedles in situ.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1485-1490
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• 2004

Recently, we have remarkable developments in intelligent robot systems. The remarkable features of intelligent robot are that it can track user, does face recognition and vital for many surveillance based systems. Advantage of face recognition when compared with other biometrics recognition is that coerciveness and contact that usually exist when we acquire characteristics do not exist in face recognition. However, the accuracy of face recognition is lower than other biometric recognition due to decrease in dimension from of image acquisition step and various changes associated with face pose and background. Factors that deteriorate performance of face recognition are many such as distance from camera to face, lighting change, pose change, and change of facial expression. In this paper, we implement a new 3D active camera system to prevent various pose variation that influence face recognition performance and propose face recognition algorithm for intelligent surveillance system and mobile robot system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.4
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• pp.639-642
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• 2012

Optical coherence tomography(OCT) can provide real-time and non-invasive subsurface imaging with ultra-high resolution of micrometer scale. However, conventional OCT systems generally have a limited imaging depth range within a depth of only 1-2 mm. To overcome the limitation, we have proposed an active surface tracking algorithm used in common-path Fourier-domain OCT system in order to extend the imaging depth range. The surface tracking algorithm based on the threshold and Savitzky-Golay filter of A-scan data was applied to real-time tracking. The algorithm has controlled a moving stage according to the sample's surface variance in real time. An OCT image obtained by the algorithm clearly show an extended imaging depth range. Consequently, the proposed algorithm demonstrated the potential for improving the conventional OCT systems with limitary depth range.