Background and ObjectivesWidespread applications of supercontinuum (SC) source lead to the possibility of ocular damages. However, the corneal damage effects induced by SC have not been explored before. The objectives of this study are to determine the rabbit corneal injury threshold for SC radiation and to examine whether the existing safety guidelines and standards are suitable for the hazard evaluation of this new kind of light source.Study Design/Materials and MethodsA series of experiments was conducted in the New Zealand white rabbit model to determine the corneal damage thresholds induced by a 770–2,500 nm SC source, with a corneal 1/e beam diameter of 0.37 mm. Through slit‐lamp biomicroscope, optical coherence tomography (OCT), and histopathology the corneal damage characteristics at the threshold level were revealed. By employing the action spectra determined through the analysis of safety guidelines and standards, the damage thresholds for SC source could be compared with the corresponding exposure limits.ResultsThe determined damage thresholds given in terms of the peak radiant exposure for exposure durations of 2.0 and 10.0 seconds were 2.1 × 103 and 7.4 × 103 J/cm2, respectively. At threshold level, corneal damages involved the epithelium and the shallower stroma, and no obvious changes could be found in the deep stroma, Descemet's membrane, and endothelium.ConclusionsThe exposure limits for the anterior parts of the eye in the wavelength range of 700–1,200 nm are overly conservative. The obtained results contribute to the knowledge base for the hazard evaluation of SC source. Lasers Surg. Med. © 2019 Wiley Periodicals, Inc.
There is an increasing use of near-infrared lasers in biomedical applications operating in the spectrum between 1300 and 1400 nm. To corroborate and expand the existing safety data for skin exposure to lasers in this wavelength region, the in-vivo ED 50 damage thresholds were determined in Guizhou miniature pigs for 1319-nm laser radiation. Exposure durations of 0.4, 1.0, and 3.0 s and 1∕e 2 beam diameters of 0.98 and 1.96 cm were employed. Damage lesion determinations were performed at 1-and 24 h post exposure. The Bliss probit analysis was employed to establish the ED 50 damage thresholds. Histopathological studies of skin damage were performed at 48 h after irradiation to reveal the damage characteristics. The skin damage thresholds at 1 h post exposure, given in peak radiant exposure, were 35.5, 36.1, and 37.1 J∕cm 2 at exposure durations of 0.4, 1.0, and 3.0 s with the spot diameter of 0.98 cm, and 28.6 J∕cm 2 at exposure duration of 3.0 s with the spot diameter of 1.96 cm. At 24 h post exposure, the ED 50 s increased slightly. Histologically, the thermal damage characteristics at the near-threshold level included gathering of the nuclear chromatin and cell vacuolation in the epidermis and deposition of blood cells in the capillary vessels. However, at the apparently above-threshold level, the damage characteristics included obvious stretching of the nuclear chromatin in the epidermis, closing of the capillary lumen, structural change of collagen fibers, and coagulative necrosis of the hair follicle cells. The damage induced by this laser could go deep into the fatty tissue. The obtained results may contribute to the knowledge base for the damage mechanisms and expand the database for the refinement of laser safety standards in the wavelength range of 1300 to 1400 nm.
With the rapid developments and widespread applications of supercontinuum (SC) sources, ocular damage induced by this new light source becomes possible and receives our concern. To explore the ocular damage effect of an SC source, a series of experiments were conducted in a chinchilla grey rabbit model to determine the invivo retinal damage thresholds induced by a 420-750 nm SC source and a 532 nm laser. For the SC source, the beam divergence and the corneal 1/e 2 beam diameter were 3.8 mrad and 2.45 mm, respectively. The determined ED 50 values given in terms of total intraocular energy (TIE) for exposure durations of 0.1, 1.0, and 10.0 s were 1.57, 12.1, and 86.0 mJ, respectively. For the 532 nm laser, the beam divergence and the corneal 1/e 2 beam diameter were 0.9 mrad and 2.25 mm, respectively. The determined ED 50 value for an exposure duration of 0.1 s was 1.39 mJ. By employing the retinal thermal action spectrum in the ICNIRP guidelines, the damage thresholds for SC sources could be compared with the exposure limits for incoherent and laser radiation. Between the 420-750 nm SC source and the 532 nm laser, no significant difference could be found for the damage effects including damage threshold, retinal lesion size, and histological damage characteristics.
Surface Plasmon Polaritons (SPPs) Propagate along the Interface between Metal and Dielectric, so that Spps can Propagate along the Designed Interface, Spread to the Specified Region and Convert Back to Light Wave. through this Method, Modulated Light can be Guided to Setting Area and the Propagation Direction can be Changed. in this Paper, a Kind of all-Optical Switch Composed of Metallic Isosceles Triangle is Introduced. the Principle of the all-Optical Switch is this. Firstly, the Modulated Light is Converted into Spps in the Metal Triangle at the Bottom Corner. then, Spps Propagate along Designed Interface between Metal and Dielectric. Finally, Spps Become Scattered Light in the Vertex of Triangle where the Signal Light also Become Scattered Light. Two Scattering Light Interfere Cancellation to Achieve the Goal that the Modulation with very Low Power Light can Control the Signal Light. the most Remarkable Advantage of the all-Optical Switch is that the Incident Angle of Modulated Light does Not Require Strictly. as Long as the Light Intensity and Phase of Light is Proper, the Aim of Extinction can be Achieve. the Reaction Speed of the all-Optical Switch is Nearly the Speed of Light. Response Time is 0.9 Femtosecond. Extinction Ratio is about 34.93558dB.The Entire Structure Size is only 1.81μm× 1μm(x×z).The all-Optical Switch has the Characteristics of Low Threshold Power, Small Size and Easily Integrated. in the Case of Relatively High Extinction, the Switch can Control Signal of any Channel. it is Able to be Applied to High-Speed, Large Capacity, Channel Spacing of 0.8nm DWDM Optical Network
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.