Electron-bombarded charge-coupled devices (CCDs) are a relatively new development in which photons are detected by a photocathode in a manner similar to an image intensifier. Instructions for operation of the tutorial appear beneath the applet window.
Photons (yellow) impinging upon the surface of the photocathode liberate photoelectrons (red), which are accelerated by a high voltage gradient and impact on the back side of a CCD. Use the Gain slider to control the voltage supplied to the photocathode and, hence, the intensity or number of photoelectrons emitted by the photocathode.
The high-energy electrons that strike the CCD generate multiple charges resulting in a modest gain of a few hundred. The advantages of this device over a cooled, slow-scan CCD are the additional gain and accompanying speed; the main disadvantages are the lower quantum efficiency of the photocathode and diminished dynamic range.
Kenneth R. Spring - Scientific Consultant, Lusby, Maryland, 20657.
John C. Long and Michael W. Davidson - National High Magnetic Field Laboratory, 1800 East Paul Dirac Dr., The Florida State University, Tallahassee, Florida, 32310.
BACK TO DIGITAL IMAGING IN OPTICAL MICROSCOPY
Questions or comments? Send us an email.
© 1998-2015 by
Michael W. Davidson and The Florida State University.
All Rights Reserved. No images, graphics, scripts, or applets may be reproduced or used in any manner without permission from the copyright holders. Use of this website means you agree to all of the Legal Terms and Conditions set forth by the owners.
Last modification: Thursday, Feb 11, 2016 at 12:09 PM
Access Count Since July 28, 2000: 32929
Visit the websites of our partners in digital imaging education: