A theoretical and experimental comparison of photon-countingcameras and CCD’s for use in astronomical speckle imaging wasperformed. Photon-counting cameras able to detect single-photonevents typically exhibit a lower quantum efficiency (QE) and suffersaturation effects at high light levels. In contrast, CCD’s offera high QE and virtually unlimited photon-count rate. However CCD’sare limited at lower light levels by noise associated with the readoutprocess. Speckle-imaging performance was quantified by derivationof the signal-to-noise ratio (SNR) of the power spectrum and theKnox–Thompson product to include CCD readout noise. Ground-basedtelescope observations at various light levels were obtained with anadvanced, high-speed, low-noise CCD camera to verify SNRexpressions. The useful operating ranges for these two camera typeswere compared by consideration of the effects of QE, readout noise, andmaximum photon-count rate. Although photon-counting camerascontinued to dominate low-light-level applications, CCD’s are shown tooffer significant improvements over photon-counting cameras for a widerange of light levels. Future reductions of readout noise will further improve CCD speckle-imaging performance.
© 1998 Optical Society of America
(010.1330) Atmospheric and oceanic optics : Atmospheric turbulence
(030.4280) Coherence and statistical optics : Noise in imaging systems
(030.6610) Coherence and statistical optics : Stellar speckle interferometry
(040.1520) Detectors : CCD, charge-coupled device
(110.6150) Imaging systems : Speckle imaging
Jerome A. Zadnik and James W. Beletic, "Effect of CCD Readout Noise in Astronomical Speckle Imaging," Appl. Opt. 37, 361-368 (1998)