• Journal of Veterinary Clinics
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• v.39 no.3
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• pp.114-120
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• 2022

The purpose of this study is to examine the status of quality control using multipurpose phantom of ultrasound equipment used in hospital of veterinary college in South Korea by using ATS-539 multipurpose phantom so as to examine quantitative and objective new image evaluation method. Specialists discussed and analyzed multipurpose phantom images acquired by using convex transducer of 10 ultrasound imaging devices, currently used in 9 veterinary colleges, at 4.0-6.0 MHz. Total 8 items that can be measured with ATS-539 multipurpose phantom including dead zone, vertical and horizontal measurement, axial/lateral resolution, sensitivity, focal zone, functional resolution and gray scale/dynamic range were evaluated. For qualitative evaluation, valid decisions were made based on dead zone, axial/lateral resolution, and gray scale/dynamic range which are resolution index, and coefficient of variation (COV) and blind referenceless image spatial quality evaluator (BRISQUE) were found to increase objectivity. As a result of experiment, all the targeted ultrasonic devices were found appropriate from qualitative evaluation items of dead zone, axial/lateral resolution, and gray scale/dynamic range. In other evaluation items, they were found to be appropriate from focal zone and vertical measurement of quantitative evaluation while inappropriate from horizontal measurement, sensitivity, and functional resolution. COV value was 0.12 ± 0.04, and BRISQUE value was 47.77 ± 2.77, both analysis results show that the noise level of all ultrasonic devices was located within tolerance range. Upon image examination using ATS-539 multipurpose phantom, they were 100% appropriate with inspection standards of dead zone, axial/lateral resolution, and gray scale/dynamic range, and besides, focal zone and functional resolution can be used as evaluation items. In the field of veterinary medicine, 8 standard items using ATS-539 multipurpose phantom and image evaluation items using COV and BRISQUE can be used as standards for quality control of ultrasonography machine.

• Journal of the Optical Society of Korea
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• v.9 no.1
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• pp.26-31
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• 2005

We describe the design and the implementation of video-rate reflection confocal scanning microscopy (CSM) using an acousto-optical deflector (AOD) for the fast horizontal scan and a galvanometer mirror (GM) for the slow vertical scan. Design parameters of the optical system are determined for optimal resolution and contrast. The OSLO simulations show that the performances of CSM are not changed with deflection angle and the wavefront errors of the system are less than 0.012λ. To evaluate the performances of designed CSM, we do a series of tests, measuring lateral and axial resolution, real time image acquisition. Due to a higher axial resolution compared with conventional microscopy, CSM can detect the surface of sub-micrometer features. We detect 138㎚ line shape pattern with a video-rate (30 frm/sec). And 10㎚ axial resolution is archived. The lateral resolution of the topographic images will be further enhanced by differential confocal microscopy (DCM) method and computational algorithms.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.576-580
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• 2005

New real-time confocal microscopy using spectral encoding technique and slit confocal aperture is proposed and designed. Spectral encoding technique, which encodes one-dimensional spatial information of a specimen in wavelength, and slit aperture make it possible to obtain two-dimensional lateral image of the specimen simultaneously at standard video rates without expensive scanning units such as polygon mirrors and galvano mirrors. The working principle and the configuration of the system are explained. The variation in axial responses for the simplified model of the system with normalized slit width is numerically analyzed based on the wave optics theory. Slit width that directly affects the depth discrimination of the system is determined by a compromise between axial resolution and signal intensity from the simulation result. On the assumption of the lateral sampling resolution of 50 nm, design variables and governing equations of the system are derived. The system is designed to have the mapping error less than the half pixel size, to be diffraction-limited and to have the maximum illumination efficiency. The designed system has the FOV of $12.8um{\times}9.6um$, the theoretical axial FWHM of 1.1 um and the lateral magnification of-367.8.

• Journal of the Optical Society of Korea
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• v.9 no.1
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• pp.32-35
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• 2005

In light microscopy, spatial resolution is limited by diffraction effect. Confocal microscopy has improved resolutions in both lateral and axial directions, but these are still limited by diffraction effect. Confocal self-interference microscopy (CSIM) uses interference between two perpendicularly polarized beams to enhance lateral resolution. In previous research, we proposed a calcite plate with its optic-axis perpendicular to the propagation angle and one of the boundary surfaces of the plate. This type of plate is not widely used to our knowledge. In this paper, we change the calcite plate to more common one, which is commercially available. This calcite plate has its optic axis in the plane of incidence. We analyze the characteristics of this calcite plate and numerically compare the performances of CSIM in previous research and CSIM with the commercial calcite plate. Numerical results show improved performance when using the commercial calcite plate

• Journal of the Korean Institute of Navigation
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• v.16 no.3
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• pp.77-85
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• 1992

Camera arrangement for depth and image correspondence is very important to the computer vision. Two conventional comera arrangements for stereo computer vision are lateral model and axial motion model. In this paper, using the axial motion stereo camera model, the algorithm for camera focal length measurement and the surface smoothness with the radiance-irradiance is proposed fro 3-dimensional image correspondence on stereo computer vision. By adapting the above algorithm, camera focal length can be measured precisely and the resolution of 3-dimensional image correspondence has been improved comparing to that of the axial motion model without the radiance-irradiance relation.

• 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 Biomedical Engineering Research
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• v.5 no.1
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• pp.77-84
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• 1984

A prototype of a linear real-time ultrasound B-scanner has been developed which has an axial resolution of 1-2mm and lateral resolution of 2-3mm. In the actual hardware and software implementations of the B-scanner, the following features were emphasized; (1) a dynamic focusing to improve resolution; (2) signal processing to obtain low noise image; (3) various functions for the user's convenience' (4) simplification of the system by an extensive use of recently developed LSI's; (5) development of a prototype at the level of a commercial product. This paper reports the experimental results of the overall system and the design approach of the analog part. The work on the digital part of the B-scanner is reported in part (II) seperately.

• Applied Microscopy
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• v.46 no.4
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• pp.176-178
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• 2016

Efficient neural circuit reconstruction requires sufficient lateral and axial resolution to resolve individual synapses and map a large enough volume of brain tissue to reveal the molecular identity and origin of these synapses. Sparse circuit reconstruction using array tomography meets many of these requirements but also has some limitations. In this minireview, the advantages and disadvantages of applicable imaging techniques will be discussed.

• Current Optics and Photonics
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• v.8 no.4
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• pp.421-426
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• 2024

The use of stimulated emission depletion (STED) microscopy has significantly improved resolution beyond the limits imposed by diffraction; Furthermore, STED microscopy adopts a 4Pi-geometry to achieve an isotropic improvement in resolution. In isoSTED microscopy, a polarizing beam splitter and retarders are used in a 4Pi cavity to split beams of identical power, generating constructive and destructive interference for lateral and axial resolution improvements, respectively. The precise alignment of the retarders is crucial for optimizing the performance of isoSTED microscopy, because this orientation affects the quality of the depletion focus, necessitating zero intensity at the center. Incomplete destructive interference can lead to unwanted fluorescence inhibition, resulting in degraded resolution and contrast. However, measuring the intensity and polarization state in each optical path of the 4Pi cavity is complex and requires additional devices such as a power meter. Here, we propose a simple and accurate alignment method for the 4Pi cavity in isoSTED microscopy. Our approach demonstrates the equal allocation of power between upper and lower beam paths and achieves complete destructive interference using a polarizing beam displacer and a single CCD camera positioned outside the 4Pi cavity.

• 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.