Radiation detector based on liquid crystal light valve for large-area imaging applications

Kang, Sang-Sik; Park, Ji-Koon; Cha, Byung-Youl; Cho, Sung-Ho; Shin, Jung Woog; Lee, Kunhwan; Nam, Sang-Hee

doi:10.1016/j.nima.2007.01.125

Cited by 4 publications

(4 citation statements)

References 5 publications

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“…[94][95][96][97] As a recent topical example, the COVID-19 detectors based on nematic and cholesteric liquid crystals can be considered. 98,99 Liquid crystals are also used in thermography for mapping of temperature and turbulent streaks, [100][101][102] X-ray radiation detection 103 and sunlight ultraviolet. [104][105][106] In a recent study, ML algorithm has been applied to the shear-sensitive liquid crystal coating (SSLCC) used for nonintrusive global wall shear stress measurements.…”

Section: Parsing the Liquid Crystal Director Fieldmentioning

confidence: 99%

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Machine learning methods for liquid crystal research: phases, textures, defects and physical properties

Piven,

Darmoroz,

Skorb

et al. 2024

Soft Matter

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Section: Parsing the Liquid Crystal Director Fieldmentioning

confidence: 99%

“…94–97 As a recent topical example, the COVID-19 detectors based on nematic and cholesteric liquid crystals can be considered. 98,99 Liquid crystals are also used in thermography for mapping of temperature and turbulent streaks, 100–102 X-ray radiation detection 103 and sunlight ultraviolet. 104–106…”

Section: Main Textmentioning

confidence: 99%

Machine learning methods for liquid crystal research: phases, textures, defects and physical properties

Piven,

Darmoroz,

Skorb

et al. 2024

Soft Matter

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show abstract

“…Third, when the electric potential applied to top and bottom electrodes is removed, variations in potential occurr as a function of the x-ray intensity because the generated electrons or holes are stored at the interface between the photoconductive and LC layer. Last, the variation in electric field across the LC layer modifies the molecular arrangement and controls the intensity of light passing through the LC cell [5,6]. A key feature of the XLV x-ray detector is that it utilizes the potential variations caused by the charges collected at the photoconductive layer, which results in a minimal lateral spread of charge and thus a high spatial resolution.…”

mentioning

confidence: 99%

Development of an x-ray detector based on polymer- dispersed liquid crystal

Hong

Kim

et al. 2015

J. Inst.

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The applications of active matrix flat-panel imagers (AMFPIs) in large-area x-ray imaging systems have increased over time but are still severely limited owing to its pixel resolution, complex fabrication processes, and high cost. As a solution, x-ray light valve (XLV) technology was introduced and expected to have a better resolution and contrast ratio than those of AMFPI, owing to its micrometer level of the LC cells and signal amplification by an external light source. The twisting angle of the LC cells was changed by charge carrier signals created in a photoconductor layer against x-rays, and the diagnostic images from XLV were acquired from the transmittance of the external light source. However, there was a possibility that the photoconductor layer may be crystallized or degenerated due to the application of high temperatures for sealing the LC layer during the fabrication process. To solve such problems, polymer-dispersed liquid crystals (PDLCs), which do not need high temperature for the sealing process of the LC layer, are used in this study instead of typical LC cells. A photoconductor and PDLC are combined to develop an x-ray detector. An external light source and optical sensor are used to investigate the light transmission of the PDLC. The PDLCs used in this paper do not need polarizers and are self-adhesive. Hence, the transmittance is very high in the transparent state, which allows for a linear x-ray response and sufficient dynamic range in digital radiography.

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“…In recent digital X-ray systems, increases in the image quality and reductions in the patient dose have been achieved primarily through technologies based on largearea active matrix flat panel detectors. However, limitations in image acquisition have appeared because the production process is too complicated and the thin-film transistor panel is pixelated [1]. Other X-ray systems such as computed radiography, which uses the concept of non-pixels to obtain high-resolution images, use photostimulable phosphors, also known as storage phosphors.…”

mentioning

confidence: 99%

Feasibility study of a multi-layer liquid-crystal-based non-pixel X-ray detector

Kim

Shin

et al. 2012

J. Inst.

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The recent study of digital X-ray detectors in medical diagnostics has focused on high-resolution image acquisition. Digital X-ray detectors use either a direct or an indirect method of converting X-ray into an electric charge. Indirect systems have low resolution due to blurring of light from the scintillator. In contrast, direct systems have higher resolution than indirect systems, but they are expensive, and systems that have large areas are difficult. This paper proposes a new structure for a non-pixel detector in order to resolve these problems by constructing multiple layers, including photoconductor and liquid crystal (LC) cell layers. First, simulations were conducted to measure changes in the transmittance and electric field of the LC cell under different applied voltages and different thicknesses of a glass layer between the LC and the photoconductor. Subsequently, non-pixel X-ray films having an optimized structure were fabricated using the optimal glass thickness and voltage obtained from the simulation results. In a previous study, X-ray film was fabricated from an LC and a photoconductor by a single integrated production process. In this study, the fabrication process was divided into two steps to prevent damage to the X-ray conversion materials caused by the high temperature used to manufacture the LC cell. The photoconductor layer was fabricated by screen-printing at room temperature on the LC cell. HgI 2 was used as the photoconductor material and an aluminum reflective layer was then deposited. The photoconductor was approximately 150-250µm thick. The linear range of LC twisting was acquired by measuring the transmittance-voltage curve; when a voltage of 1.3V to 2.2V is applied to the LC

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Radiation detector based on liquid crystal light valve for large-area imaging applications

Cited by 4 publications

References 5 publications

Machine learning methods for liquid crystal research: phases, textures, defects and physical properties

Machine learning methods for liquid crystal research: phases, textures, defects and physical properties

Development of an x-ray detector based on polymer- dispersed liquid crystal

Feasibility study of a multi-layer liquid-crystal-based non-pixel X-ray detector

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