Author
Charles G. Askins
Bio: Charles G. Askins is an academic researcher from United States Naval Research Laboratory. The author has contributed to research in topics: Optical fiber & Fiber Bragg grating. The author has an hindex of 21, co-authored 79 publications receiving 5020 citations.
Papers published on a yearly basis
Papers
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TL;DR: In this paper, the authors review the recent developments in the area of optical fiber grating sensors, including quasi-distributed strain sensing using Bragg gratings, systems based on chirped gratings and intragrating sensing concepts.
Abstract: We review the recent developments in the area of optical fiber grating sensors, including quasi-distributed strain sensing using Bragg gratings, systems based on chirped gratings, intragrating sensing concepts, long period-based grating sensors, fiber grating laser-based systems, and interferometric sensor systems based on grating reflectors.
3,665 citations
TL;DR: More than 450 fiber Bragg gratings have been fabricated in line during the draw process in a period of 1 h with single pulses of a KrF excimer laser.
Abstract: More than 450 fiber Bragg gratings have been fabricated in line during the draw process in a period of 1 h with single pulses of a KrF excimer laser. Arrays of gratings have been written at different Bragg wavelengths by using an automated, computer-controlled interferometer.
177 citations
01 Feb 1984-Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms
TL;DR: In this article, the authors review recent progress in understanding the behavior of optical fiber waveguides when they are exposed to ionizing radiation and identify the defect centers which cause these absorptions.
Abstract: This paper will review recent progress in understanding the behavior of optical fiber waveguides when they are exposed to ionizing radiation. Not only have the growth and recovery of the radiation-induced attenuations been thoroughly characterized, in some cases the defect centers which cause these absorptions have been identified, and means for reducing the radiation sensitivity of the fibers have become apparent. The behavior of the radiation-induced loss is described in terms of parameters such as fiber composition and dopants, fiber structure, wavelength and intensity of the light source, temperature, total dose, time after irradiation, dose rate, and radiation history.
148 citations
TL;DR: Narrow-line, permanent Bragg reflection gratings have been created in Ge-doped silica-core optical fibers by interfering beams of a single 20-ns pulse of KrF excimer laser light.
Abstract: Narrow-line, permanent Bragg reflection gratings have been created in Ge-doped silica-core optical fibers by interfering beams of a single 20-ns pulse of KrF excimer laser light. Of the fibers studied, the highest reflectance value of ~2% was observed with a linewidth (FWHM) of 0.1 nm, which corresponds to a 2-mm grating length with an index modulation of ~3 x 10(-5).
126 citations
TL;DR: In this article, the authors review the results of recent work at the Naval Research Laboratory where optical fiber strain sensors have been used on spacecraft structures and ground test hardware for structural health monitoring, shape determination, and spacecraft qualification testing.
Abstract: Optical fiber sensors offer a number of advantages for spacecraft applications. A principal application is strain sensing for structural health monitoring, shape determination, and spacecraft qualification testing. This paper will review the results of recent work at the Naval Research Laboratory where optical fiber strain sensors have been used on spacecraft structures and ground test hardware. The sensors have been both surface mounted to the structure and embedded in fiber-reinforced polymer composites. The issue of potential strength reduction of high-performance composites due to embedded optical fiber sensors and leads has been studied, low-cost fabrication of tubular struts with embedded sensors has been demonstrated, and a novel technique for fiber ingress-egress from composite parts has been developed. Applications of fiber sensors discussed in this paper include distributed dynamic strain monitoring of a honeycomb composite plate and a lightweight reflector during acoustic qualification tests, ultrahigh-sensitivity static strain and temperature measurements for precision structures, and on-line system identification of a lightweight laboratory truss.
106 citations
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TL;DR: In this paper, the authors review the recent developments in the area of optical fiber grating sensors, including quasi-distributed strain sensing using Bragg gratings, systems based on chirped gratings and intragrating sensing concepts.
Abstract: We review the recent developments in the area of optical fiber grating sensors, including quasi-distributed strain sensing using Bragg gratings, systems based on chirped gratings, intragrating sensing concepts, long period-based grating sensors, fiber grating laser-based systems, and interferometric sensor systems based on grating reflectors.
3,665 citations
TL;DR: This article reviews the recent progress in optical biosensors that use the label-free detection protocol, in which biomolecules are unlabeled or unmodified, and are detected in their natural forms, and focuses on the optical biosENSors that utilize the refractive index change as the sensing transduction signal.
2,060 citations
TL;DR: Among the various fiber-optic sensor technologies, especially, technologies such as fiber grating sensors, fiber- Optic gyroscopes, and fiber-Optic current sensors are discussed with emphasis on the principles and current status.
1,610 citations
TL;DR: In this paper, the authors reviewed recent research on fiber optic long-period gratings (LPGs) with emphasis placed upon the characteristics of LPGs that make them attractive for applications in sensing strain, temperature, bend radius and external index of refraction.
Abstract: Recent research on fibre optic long-period gratings (LPGs) is reviewed with emphasis placed upon the characteristics of LPGs that make them attractive for applications in sensing strain, temperature, bend radius and external index of refraction. The prospect of the development of multi-parameter sensors, capable of simultaneously monitoring a number of these measurands will be discussed.
1,203 citations
TL;DR: In-fibre Bragg grating (FBG) sensors are one of the most exciting developments in the field of optical fiber sensors in recent years as discussed by the authors, and significant progress has been made in applications to strain and temperature measurements.
Abstract: In-fibre Bragg grating (FBG) sensors are one of the most exciting developments in the field of optical fibre sensors in recent years. Compared with conventional fibre-optic sensors, FBG sensors have a number of distinguishing advantages. Significant progress has been made in applications to strain and temperature measurements. FBG sensors prove to be one of the most promising candidates for fibre-optic smart structures. This article presents a comprehensive and systematic overview of FBG sensor technology regarding many aspects including sensing principles, properties, fabrication, interrogation and multiplexing of FBG sensors. It is anticipated that FBG sensor systems will be commercialized and widely applied in practice in the near future due to the maturity of economical production of FBGs and the availability of cost effective interrogation and multiplexing techniques.
1,170 citations