A large core polymer optical fibre sensor for x-ray dosimetry based on luminescence occurring in the cladding

Abstract

An optical fibre sensor for short pulse duration x-ray dosimetry is presented. The sensor is based on luminescence generated in the cladding of a 1 mm core diameter polymer optical fibre which has been doped with a radioluminescent phosphor. On interaction with x-rays, this phosphor emits visible light, part of which is coupled to the fibre core through a combination of surface roughness at the core-cladding interface and through evanescent wave coupling of these guided waves. From here it is transmitted to an optoelectronic photodetector for monitoring. A 15 cm fibre sensor was used for the experiment which was conducted using a pulsed x-ray source normally employed for the preionization of excimer lasers. The results are calibrated against the emission intensity from a scintillating plastic block and a pen dosimeter. The peak output signal of the fibre sensor increases linearly with the dose produced by the x-ray source. There is also a discussion on the long-term stability of such a sensor, the expansion of this sensor into a multi-point device and methods to improve the efficiency of the luminescence coupling from cladding to core for large core polymer fibres included.

Highly Sensitive Extrinsic X-Ray Polymer Optical Fiber Sensors Based on Fiber Tip Modification

“…All the samples have been made essentially following the procedure described by McCarthy et al [6,7,15]. Thus, the scintillating medium is a mixture of the scintillating material (GADOX) with general purpose epoxy resin (EVO-STICK Epoxy Control).…”

“…This kind of radiation can be found in nature through radioactive elements, but also can be artificially produced in areas such as nuclear power plants [1,2], industrial facilities [3][4][5], and for diagnostic and therapeutic healthcare applications [6][7][8][9]. Therefore, a proper protection protocol for irradiation prevention must be based on the precise measurement of radiation levels in these areas [10][11][12].…”

“…A current trend in this field, is the use of extrinsic polymer optical fiber (POF) based dosimeters or detectors [6,8,[10][11][12]. These arrangements add the well-known advantages of the use of optical fibers, such as immunity to electromagnetical interferences, small size and weight, multiplexing capabilities, to the easy handling and low cost of the POF.…”

“…Since the fiber itself is not sufficiently radiation sensitive for low dose applications, a suitable transducer must be added to the fiber. Rare earth doped phosphors have been successfully applied for this purpose [6,14,15]. Then, the operational principle of such extrinsic sensors is the radiation induced fluorescence, in which the impinging radiation on the phosphor release visible light that is gathered by the POF and driven to the optoelectronics unit to be measured [10].…”

Fluorescence-based remote irradiation sensor in liquid-filled hollow-core photonic crystal fiber

“…Typically, the tip of an optical fiber is coated with a suitable luminescent material, and the emitted radiation is collected by the fiber core and transmitted to the diagnostics. While this method enables detection from the ultraviolet (UV) to the x-ray spectral regions [1][2][3][4], spatially resolved measurements are cumbersome and difficult, especially in hazardous environments. In addition, the detectable spectral range is limited by the properties of the luminescent material, and material degradation (e.g., photo-darkening) can severely limit applications when the irradiation levels are high.…”