We have developed a silicon MEMS optical accelerometer in which the motion of the proof mass is mechanically
amplified using a V-beam mechanism prior to transduction. The output motion of the V-beam is detected using a Fabry-Pérot interferometer (FPI) which is interrogated in reflection mode via a single-mode optical fibre. Mechanical
amplification allows the sensitivity of the accelerometer to be increased without compromising the resonant frequency or
measurement bandwidth. We have also devised an all-optical method for calibrating the return signal from the FPI, based
on photothermal actuation of the V-beam structure using fibre-delivered light of a different wavelength. A finite-element
model has been used to predict the relationship between the incident optical power and the cavity length at steady state,
as well as the step response which determines the minimum time for calibration. Prototype devices have been fabricated
with resonant frequencies above 10 kHz and approximately linear response for accelerations in the range 0.01 to 15 g.
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
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.