We present a novel technique for the calibration of a high speed FBG interrogation system which incorporates an
Arrayed Waveguide Grating (AWG). It uses temperature tuning to wavelength sweep the AWG to generate calibration
data and to determine the optimum temperature of AWG for the actual test. For ideal operation the FBG wavelengths
under zero stimulus would lie midway between the International Telecommunications Union (ITU) grid wavelengths of
the AWG. The attached FBG wavelengths cannot always be accurately prescribed since they vary during attachment,
and with temperature. This technique reduces this constraint and enables different detector gains to be used on different
channels for system optimisation.
Ultra fast X-ray imaging has been undertaken upon AWE's and Sandia National Laboratories' radiation effects x-ray
simulators. These simulators typically yield a single very short (<20ns) pulse of high-energy (MeV endpoint energy
bremsstrahlung) x-ray radiation with doses in the kilorad (krad (Si)) region. X-ray source targets vary in size from 2 to
25cm diameter, dependent upon the particular simulator. Electronic imaging of the source x-ray emission under dynamic
conditions yields valuable information upon how the simulator is performing. The resultant images are of interest to the
simulator designer who may configure new x-ray source converter targets and diode designs. The images can provide
quantitative information about machine performance during radiation effects testing of components under active
conditions. The paper highlights the new ULTRA fast framing camera, developed by Photek Ltd. in-conjunction with
AWE, which is capable of imaging up to 500 Million frames per second. Unique sequences of time resolved high spatial
resolution images, have been captured in the nanosecond timeframe with zero interframe time, of the source x-rays,
utilising our novel configurations.
Further, a dedicated diagnostic experiment capturing time resolved x-ray phenomenon, utilising a customised streak
tomographic technique, with a multi-billion frames per second recording and 2048 frames capture sequence capability, is
described. The fundamental principles of our imaging systems can be applied to other visible and x-ray imaging
scenarios.
We report an accelerometer based upon a simple fibre cantilever constructed from a short length of multicore fibre
(MCF) containing fibre Bragg gratings (FBGs). Two-axis measurement is demonstrated up to 3 kHz.
X-ray imaging has been undertaken on Sandia National Laboratories' radiation effects x-ray simulators. These
simulators typically yield a single very short (<20ns) pulse of high-energy (MeV endpoint energy bremsstrahlung) x-ray
radiation with doses in the kilorad (krad (Si)) region. X-ray source targets vary in size from 2 to 25cm diameter,
dependent upon the particular simulator. Electronic imaging of the source x-ray emission under dynamic conditions
yields valuable information upon how the simulator is performing. The resultant images are of interest to the simulator
designer who may configure new x-ray source converter targets and diode designs. The images can provide quantitative
information about machine performance during radiation effects testing of components under active conditions. The
effects testing program is a valuable interface for validation of high performance computer codes and models for the
radiation effects community. A novel high-energy x-ray imaging spectrometer is described whereby the spectral energy
(0.5 to 1.8MeV) profile may be discerned from the digitally recorded and viewable images via a
pinhole/scintillator/CCD imaging system and knowledge of the filtration parameters. Unique images, analysis and an
evaluation of the capability of the spectrometer are presented.
Pioneering x-ray imaging has been undertaken on a number of AWE’s and Sandia National Laboratories’ radiation effects x-ray simulators. These simulators typically yield a single very short (<50ns) pulse of high-energy (MeV endpoint energy bremsstrahlung) x-ray radiation with doses in the kilorad (krad(Si)) region. X-ray source targets vary in size from 2 to 25cm diameter, dependent upon the particular simulator. Electronic imaging of the source x-ray emission under dynamic conditions yields valuable information upon how the simulator is performing. The resultant images are of interest to the simulator designer who may configure new x-ray source converter targets and diode designs. The images can provide quantitative information about machine performance during radiation effects testing of components under active conditions. The effects testing program is a valuable interface for validation of high performance computer codes and models for the radiation effects community. A novel high-energy x-ray imaging spectrometer is described whereby the spectral energy (0.1 to 2.5MeV) profile may be discerned from the digitally recorded and viewable images via a pinhole/scintillator/CCD imaging system and knowledge of the filtration parameters. Unique images, analysis and a preliminary evaluation of the capability of the spectrometer are presented. Further, a novel time resolved imaging system is described that captures a sequence of high spatial resolution temporal images, with zero interframe time, in the nanosecond timeframe, of our source x-rays.
Electronic imaging has been undertaken upon a selection of AWE's high power x-ray pulse accelerators used for radiation effects testing on electronic components and small sub-systems. Principally an experimental configuration, based upon a pinhole scintillator combination, has been implemented to test the feasibility of recording by an electronic imaging system for high energy (3MeV) and high dose (>16krads) x-ray pulse sources. Recording by CCD based imaging technology has been used to image and verify the uniformity of the bremsstrahlung source. The accelerators of interest are the Short Pulse Experimental Electron Device (SPEED), which is a 1 MeV, very short (15 ns) pulse, high dose, bremsstrahlung source and the accelerator EROS (Energetic Radiation Of Samples), which is a 3 MeV, 40 krad, 85 ns pulse source. Quantification of Scintillator and camera parameters are highlighted in the paper and the unique electronic images, of the respective sources, are presented. Some future temporal imaging concepts with resolution approaching one nanosecond are also highlighted. The fundamental principles of the imaging system can be applied to other pulsed x-ray scenarios.
Conventional ultra-high speed electronic framing cameras have typically employed either a multiplicity of image intensifiers and CCD cameras aligned on a common optical axis (example -- the Hadland 468). Alternatively, a single photo-cathode and a means of deflecting the resultant 'electron image' to differing areas on a phosphor screen which can then be recorded by a conventional CCD camera (example -- the Ultranac), shuttering being performed by the intensifier. These conventional techniques are powerful but inevitably lead to highly complex camera systems. The techniques described, center upon a new image intensifier construction. The photo- cathode of an otherwise standard generation 2 image intensifier, is fabricated in such a manner that separate portions or areas of the photo-cathode may be gated independently of others, creating in effect a multiplicity of separate 'intensifier' channels. Coupling this technique to a recently developed novel beam splitter plus a single large format CCD camera (covering all 'channels' simultaneously), has resulted in an extremely compact, rugged and flexible ultra high speed camera system. A further advantage of the technique is the simplicity by which advances in solid state camera technology may be exploited. These new techniques offer a new range of camera systems, allowing frame rates of up to 100,000,000 frames per second (fps) or more, of 4 to 136 independent frames with resolutions of up to 1000 X 1000 pixels per image with other user defined spectral filtering and or color options. Characterization of the true optical gating properties of the camera 'intensifier channels' operating in the nanosecond region is also quantified. Finally, example images and sequences are presented plus an overview of some of the new applications that these camera systems make feasible.
Radiation Imaging diagnostics invariably utilize gated micro-channel plate intensified components matted to solid state camera systems. Imaging is accomplished by conversion of radiation patterns to light which is viewed by optical sensors. This paper describes the effects of transient ionizing radiation directly impinging upon the solid state photo sensors which are typically used in the camera systems. These spurious radiation effects can cause degradation of the camera image. Gamma and neutron studies from earlier work are reviewed as well as electronic and electro-optic mitigation techniques to alleviate the problems of unwanted induced radiation artifacts in these photo sensors. Characterization of the true optical gating properties of the gated micro-channel plate operated in the nanosecond region (which aids image capture in pulse radiation scenarios) is described. X-Ray radiography imaging with large format gated intensified camera systems using high energy pulsed sources in the MeV region is also described.
A high resolution fast readout camera system has been developed around a specialized full frame 512 * 512 pixel format CCD sensor in conjunction with EEV Ltd. An equivalent readout rate of 600 frames per second with a spatial resolution of 24 line pairs per mm at the Nyquist limit is achieved. A binning capability increases the readout rate by up to a factor of four. The system dynamic range is in excess of 1000:1. System features include image analysis for computer with dedicated software, non volatile memory, high resolution and real time displays, instantly reset able, single shot image capture capability and remote head operation.
Limitations of standard three-phase frame transfer CCDs in high-speed operation are discussed with particular attention given to parallel and serial transfer, and the output amplifier. It is noted that in most CCD designs the greatest limitation on high-speed performance occurs in a serial register. At very high clock frequencies (greater than 30 MHz) actual generation and transmission of the necessary pulses can become the dominant restriction. Multiple output registers make it possible to obtain much higher readout frequencies. Design of a high-speed device capable of being fully readout in less than 2 mS is presented.
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