A theoretical and experimental comparison of photon-counting cameras and CCD’s for use in astronomical speckle imaging was performed. Photon-counting cameras able to detect single-photon events typically exhibit a lower quantum efficiency (QE) and suffer saturation effects at high light levels. In contrast, CCD’s offer a high QE and virtually unlimited photon-count rate. However CCD’s are limited at lower light levels by noise associated with the readout process. Speckle-imaging performance was quantified by derivation of the signal-to-noise ratio (SNR) of the power spectrum and the Knox–Thompson product to include CCD readout noise. Ground-based telescope observations at various light levels were obtained with an advanced, high-speed, low-noise CCD camera to verify SNR expressions. The useful operating ranges for these two camera types were compared by consideration of the effects of QE, readout noise, and maximum photon-count rate. Although photon-counting cameras continued to dominate low-light-level applications, CCD’s are shown to offer significant improvements over photon-counting cameras for a wide range of light levels. Future reductions of readout noise will further improve CCD speckle-imaging performance.
© 1998 Optical Society of AmericaFull Article | PDF Article
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