Thermoluminescence (TL) flat optical fibers (FF) have been proposed as radiation sensor in medical dosimetry for both diagnostic and radiotherapy applications. A flat optical fiber with nominal dimensions of (3.226 × 3.417 × 0.980) mm3 contains pure silica SiO2 was selected for this research. The FF was annealed at 400°C for 1 h before irradiated. Kinetic parameters and dosimetric glow curve of TL response were studied in FF with respect to electron irradiation of 6 MeV, 15 MeV and 21 MeV using linear accelerator (LINAC) in the dose range of 2.0-10.0 Gy. The TL response was read using a TLD reader Harshaw Model 3500. The Time-Temperature-Profile (TTP) of the reader used includes; initial preheat temperature of 80°C, maximum readout temperature is 400°C and the heating rate of 30°Cs-1. The proposed FF shows excellent linear radiation response behavior within the clinical relevant dose range for all of these energies, good reproducibility, independence of radiation energy, independence of dose rate and exhibits a very low thermal fading. From these results, the proposed FF can be used as radiation dosimeter and favorably compares with the widely used of LiF:MgTi dosimeter in medical radiotherapy application.
The application of laser shearography is becoming an acceptance tools in industrial NDT and material evaluation. The method has an advantage over other techniques due to non-contact real time measurement via a CCD camera. Recent application shows that this technique could offer a quantitative analysis in determining the magnitude of defect and strain of an inspected object. However problem of error in measurement particularly related to the optical phase change is a major concerned, it is known that the magnitude of the optical phase error could be associated with the optical,
mechanical and electronics factors. This paper describes the effect of relative maximum phase change difference with load variation for difference shearing amount and the optical phase magnitude change with the change of shearing direction. Experiment used cantilever beam clearly indicated that the error difference with the variation of load applied to a maximum fringe density of 5mm shearing amount provides 6-12% compared with 10-12% of 15mm shearing amount. The phase magnitude changes its sign from negative to positive value in contrary to the direction of upper speckle shearing.
This paper aims at assessing of corrosion defects in standard petroleum pipelines by shearography method. Shearography
reveals the stress-affected zone due to additional loading that can be realized by the laser speckle correlation on the
inspected object. In this study, the artificial corrosion in pipeline is modeled by creating circular defects of different
depths and sizes. An internal air pressure was exerted to the 7mm thick pipe wall. The results show that change of
internal pressure is an effective means to reveal corrosion activity in the pipelines. The speckle correlation for corrosion
of more than 3mm depth with ▵P≥0.24MPa can clearly be observed. For comparison, radiography technique is used to
correlate the depth and size of the corrosion defects and finally to detect the location of the corrosion area.
ESPSI or shearography has been successfully used in non-destructive testing (NDT) for measuring the derivative out-of-plane displacement, w/x and/or w/y, and recently a few investigations of derivative in-plain displacement, u/x, v/y, u/y and v/x have been reported. The demand of quantitative measurement has encouraged manufacturers to produce a quantitative shearography system. However, errors arising from numerous sources, including wavefront divergence and object geometry are not taken into account when calculating the interferometer fringe function and quantifying the data. In this paper the novel approach in quantified error that propagates from the divergence illumination wavefront is presented. The theoretical error is formulated by means of mathematical approach that comprises of three dependent variables, the inspected object distance, the object size (field area covered by the CCD camera) and the illumination angle. The error defined by the difference of phase data using divergence illumination object wavefront compared to phase data that is measured by using collimated illumination wavefront. Theoretical analysis and experimental validation indicates that the magnitude of the maximum phase change difference due to the divergence of illumination wavefront to exceed 10% for out-of-plane and 40% for in-plane analysis.
The application of optical metrology using Electronics Speckle Pattern Shearing Interferometry (ESPSI) in industry, is becoming more prevalent as a method of quality assurance and non-destructive testing (NDT). ESPSI provides non-contact full-field inspection of the test object generating displacement derivative data. The trend of using ESPSI in quality assurance in NDT involves the desire for quantitative measurement. ESPSI may be used for out-of-plane displacement derivative (slope) measurements ((delta) w/(delta) x) or potentially in-plane slope measurements (such as (delta) u/(delta) x), depending on optical configurations and object boundary conditions. Current concern is focussed on accuracy of commercial ESPSI systems and questioning the extent of error compensation in the associated fringe software systems. This paper presents studies which have been analyzing in-plane derivative measurement accuracy, as a function of object illumination wave-front divergence. Theoretical error analysis supported by experimental analysis has been performed using restrained aluminum alloy cantilever beam. The relative error is measured by comparing displacement derivative data of measurements using divergent illumination with respect to collimated illumination. The measurement error has been found to be dependent on the direction of illumination and the shearing amount at a fixed distance, with certain combinations producing values exceeding 30%.
Electronic Speckle Pattern Shearing Interferometry (ESPSI) is becoming a common tool for the qualitative analysis of material defects in the aerospace and marine industries. Current trends in the development of this optical metrology nondestructive testing (NDT) technique is the introduction of quantitative analysis, which attempts to detail the defects examined and identified by the ESPSI systems. Commercial systems use divergent laser illumination, this being a design feature imposed by the typically large sizes of objects being examined, which negates the use of collimated optics. Furthermore, commercial systems are being applied to complex surfaces which distort the understanding of the instrumentation results. The growing commercial demand for quantitative out-of-lane and in-plane ESPSI for NDT is determining the quality of optical and analysis instrument. However very little attention is currently being paid to understanding, quantifying and compensating for the numerous error sources which are a function of ESPSI interferometers. This paper presents work which has been carried out on the measurement accuracy due to the divergence of the illumination wavefront and associated with the magnitude of lateral shearing function. The error is measured by comparing measurements using divergent (curvature) illumination with respect to collimated illumination. Results show that the error is increased by approximately a power factor as the distance from the illumination source to the object surface decreases.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.