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Low light level charge coupled devices (L3CCDs) have recently been developed, incorporating on-chip gain. They may be operated to give an effective readout noise much less than one electron by implementing an on-chip gain process allowing the detection of individual photons. However, the gain mechanism is stochastic and so introduces significant extra noise(More)
Numerical Simulation is an essential part of the design and optimisation of astronomical adap-tive optics systems. Simulations of adaptive optics are computationally expensive and the problem scales rapidly with telescope aperture size, as the required spatial order of the correcting system increases. Practical realistic simulations of AO systems for(More)
We present a summary of the activity of the Cambridge Optical Aperture Synthesis Telescope (COAST) team and review progress on the astronomical and technical projects we have been working on in the period 2002– 2004. Our current focus has now moved from operating COAST as an astronomical instrument towards its use as a test-bed for strategic technical(More)
A technique used to accelerate an adaptive optics simulation platform using reconfigurable logic is described. The performance of parts of this simulation has been improved by up to 600 times (reducing computation times by this factor) by implementing algorithms within hardware and enables adaptive optics simulations to be carried out in a reasonable time(More)
Recently, low light level charge coupled devices (L3CCDs) capable of on-chip gain have been developed, leading to sub-electron effective readout noise, allowing for the detection of single photon events. Optical interferometry usually requires the detection of faint signals at high speed and so L3CCDs are an obvious choice for these applications. Here we(More)
Group delay fringe tracking using spectrally-dispersed fringes is suitable for stabilising the optical path difference in ground-based astronomical optical interferometers in low light situations. We discuss the performance of group delay tracking algorithms when the effects of atmospheric dispersion, high-frequency atmospheric temporal phase variations,(More)
We present a design improvement for a recently proposed type of Shack-Hartmann wavefront sensor that uses a cylindrical (lenticular) lenslet array. The improved sensor design uses optical binning and requires significantly fewer detector pixels than the corresponding conventional or cylindrical Shack-Hartmann sensor, and so detector readout noise causes(More)
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