LOW-LIGHT IMAGING: Novel back-illuminated CCD enhances low-light-level detection

摘要

Conventional CCDs come in several forms, each with certain disadvantages for low-light imaging; a new take on back-illuminated technology resolves these issues while maintaining the benefits. Since their invention in 1969, CCDs have been used to detect faint light from entities that range from stellar objects at the edge of the known universe to nanospheres under a microscope--and practically everything in between. Key features that have enabled low-light CCD cameras to facilitate numerous breakthroughs in both the life sciences and physical sciences include greater than 90percent peak quantum efficiency (QE), very low read noise of 2 e- rms or less, excellent linearity, 100percent fill factor, and outstanding charge-transfer efficiency. About ten years ago, a variant of CCDs known as electron-multiplying CCDs (EMCCDs) was developed. In addition to the features noted previously, EMCCDs are able to achieve subelectron read noise at high frame rates, allowing single-photon detection. Thus, CCD and EMCCD cameras are commonly the instruments of choice for scientific applications ranging from steady-state astronomical imaging to dynamic single-molecule imaging, and from widefield imaging to spectroscopy.