The absolute instruments like the Maxwell’s fisheye (MFE) lens with aberration-free imaging properties have found interesting applications such as waveguide crossing. The flat wavefront of an optical ...wave in the waveguide does not match with the circular wavefront of the circular MFE lens at its edge, hence, we design and study the performance of a square MFE lens as photonic crystal waveguide crossing medium. We also have truncated the square MFE lens to a cross-shaped lens to squeeze it inside the crossing waveguides, therefore, practically no extra footprint is consumed by the truncated MFE lens. The numerical simulations show that graded photonic crystal-based implementation of the truncated MFE lens provides a bandwidth of 186 nm covering the entire S- and C-bands and partially covering the E- and L-bands of optical communication. The crosstalk levels are lower than −18 dB while the average insertion loss is 0.32 dB in the C-band.
Abstract We analysed the skulls and faces of Korean subjects using anthropometric methods to understand the anatomical characteristics of the eyeball and eye orbit region of Korean population and to ...determine the correlations between the hard and soft tissues around the eyeball and eye orbit region. In total, 82 sections in the region were measured to determine the correlations; among them, 34 showed significant differences by sex, and 6 showed significant differences by age. As the distance from the centre of the eye lens to the eye orbit is calculated as a ratio, we determined that the centre of the eye lens is located relatively on the lateral and superior position in each eye orbit in front view. Fourteen sections that could be used for craniofacial reconstruction/approximation in men and women were selected. Regression equations were derived according to the correlation of each section, and their reliabilities were verified by out of sample validation tests. Therefore, our results increase the accuracy of eyeball position determination, which would be useful for more efficient craniofacial reconstruction/approximation of the Korean population and should improve the efficiency of facial recognition.
Mandatory eye lens monitoring for exposed workers who are liable to receive an equivalent dose to the lens of the eye higher than 15 mSv in one year, required by the new European Basic Safety ...Standard 2013/59 and the recommendation given by the International Commission on Radiological Protection to lower the annual dose limit for the lens of the eye to 20 mSv, have put dosimetry services using Panasonic dosemeters in a difficult position. There are no commercially available eye lens dosemeter holders to fit Panasonic TLD pellets. Therefore, we designed and 3D printed inexpensive, splash proof, reusable and comfortable holders to fit a Panasonic nLi2nB4O7:Cu pellet. The eye lens dosemeter consists of an acrylonitrile butadiene styrene (ABS) plastic holder with a slot for a TLD pellet. The slot with the TLD pellet is covered by a heat-shrink tube and shortly heated with hot air to shrink wrap. Results of combined energy/angular response measurements, for all photon radiation qualities used, relative to N-100 at 0° as the reference energy, were within IEC 62387:2012 limits. Additionally, electron spin resonance spectroscopy was used to test the effect of irradiation to the degradation properties of the plastic ABS holder. The dosemeter is to be worn fixed to a headband, close to the eye, on the left side of the head or in the middle of the forehead.
•An inexpensive and comfortable eye lens dosimeter holder can be 3D printed.•The 3D-printed holder fits a Panasonic TL single dosimeter element.•Holders with Li2B4O7 TLD are suitable for Hp(3) measurements in IR and IC.•Properties of the ABS plastic are not affected by radiation in low range.
The lobster eye lens uses square channels to reflect and converge light. It has no fixed optical axis and possesses advantages such as a broad field of view (FOV) and no chromatic aberration. ...Moreover, lobster eye lenses based on microporous optics manufacturing technology have been successfully applied to the spatial detection of soft X-ray spectra. Based on the penetrability of hard X-rays, lobster eye lenses can detect the perspective of hidden targets, which can be applied to fields such as safety inspection and industrial flaw detection. This study proposes an algorithm for comprehensive analysis of the imaging ability of a hard X-ray lobster eye lens, focusing on the stray rays transmitted by high-penetration X-rays. The simulation results showed that the point-spread function of the off-axis FOV is different. With the increase in the photon energy, the enhanced superposition effect of the cross-arm decreases the image contrast. Both the simulated and experimental images show that the image contrast decreases as the photon energy increases. The image contrast can be improved by adding more Pb to the materials used to create the lobster eye lens owing to the strong attenuation ability of Pb to X-rays. These results can contribute to the improvement of lobster eye lenses in X-ray backscatter imaging.
•Lobster eye lenses can detect the perspective of hidden targets using hard X-rays.•We analyse imaging of a large-field-of-view hard X-ray lobster eye lens.•The analysis focuses on the stray light transmitted by high-penetration X-rays.•The image contrast can be improved by adding more Pb.•Findings contribute to improving lobster eye lenses in X-ray backscatter imaging.
Abstract This retrospective study aimed to compare the outcomes of modified double-flanged sutureless scleral fixation versus sutured scleral fixation. Medical records of 65 eyes from 65 patients who ...underwent double-flanged scleral fixation (flange group) or conventional scleral fixation (suture group) between 2021 and 2022 were reviewed. Visual and refractive outcomes, as well as postoperative complications, were compared 1, 2, and 6 months after surgery. We included 31 eyes in the flange group and 34 eyes in the suture group. At 6 months postoperatively, the flange group showed better uncorrected visual acuity (0.251 ± 0.328 vs. 0.418 ± 0.339 logMAR, P = 0.041) and a smaller myopic shift (− 0.74 ± 0.93 vs. − 1.33 ± 1.15 diopter, P = 0.007) compared to the suture group. The flange group did not experience any instances of iris capture, while the suture group had iris capture in 10 eyes (29.4%; P < 0.001). In the flange group, all intraocular lenses remained centered, whereas in the suture group, they were decentered in 8 eyes (23.5%; P = 0.005). The double-flanged technique not only prevented iris capture and decentration of the intraocular lens but also reduced myopic shift by enhancing the stability of the intraocular lens.
Because of the negative impact of radiation on the eye lens and the changes recommended by the International Commission on Radiological Protection (ICRP) 103 (2007) from 150 to 20 mSv (2 rem, the ...Regulation of BAPETEN Head No. 4 (2013) article 56 give the instruction that Monitoring of eye lens dose should be implemented starting from March 13, 2016, more intensive around the eye lens. To prepare eye lens dose assessment, The Center for Safety Technology and Radiation Metrology (CSTRM) - NNEA study the response of TLD-700H against the X-ray: N (80), N (100) and N (120) energies (usually used in the interventional radiology). Goals and objectives of this study were to obtain the response/calibrated TLD-700H which is traceable to the international system (SI) and TLD-700H can be used for an eye lens dose assessment in Indonesia. Twenty-one TLDs were irradiated with seven dosage variations (0.1; 0.5; 1; 5; 10; 15; 20) mSv at the Secondary Standard Dosimetry Laboratory (SSDL) - Jakarta. After being stored for 24 hours, the TLD were read by using TLD-Reader. The Dosimeter Response, R against doses of X-ray were: R(N80) = 34.595x + 0.1262; R² = 0.9986; R(N100) = 24.484x + 1.1357; R² = 0.9993; and R(N120) = 27.908x - 5.1065; R² = 0.9971. R: correlation coefficient, x: doses; These calibration responses can be used for eye lens dose assessment in Indonesia.
The imaging properties of the Maxwell’s fisheye (MFE) lens makes it a viable candidate to implement power coupling between different types of waveguides. A coupler based on the MFE lens is designed ...to couple a square lattice photonic crystal to a triangular lattice one. The MFE lens is implemented as ring-based multilayer and graded photonic crystal (GPC) structures. The performance of the ring-based MFE lens is better than the GPC-based one in the C-band of optical communication. The proposed ring-based MFE coupler has a footprint of 3.62×3.62μm and covers the entire C and U bands. The S and L bands are partially covered. The average insertion loss of 0.1dB and the maximum return loss of -11dB in the C-band is achieved.
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