Today's trade publications have been touting the benefits of CMOS-based imagers over their CCD counterparts. CCD designs, they say, will be easier to fabricate because they use "standard" CMOS fabrication lines as opposed to the specialized processes required by CCDs.
Today's trade publications have been touting the benefits of CMOS-based imagers over their CCD counterparts. CCD designs, they say, will be easier to fabricate because they use "standard" CMOS fabrication lines as opposed to the specialized processes required by CCDs. CCDs continue to provide superior performance over CMOS imagers, however. This month, we take a look at some sites that offer insight into the differences between the two technologies.
As a designer and integrator of cooled integrating charge-coupled-device (CCD) digital imaging systems, Apogee Instruments (Tucson, AZ) maintains a Web site that contains information on its products and their application in astronomy, microscopy, spectroscopy, and radiography. Of special interest, however, is a section called "CCD University," which provides information on such CCD specifications as quantum efficiency, blooming, pixel binning, and system gain. Using these data you will be able to directly compare the differences between CCDs and CMOS devices.
Devices and cameras
Entering "CMOS CCD comparison" into the on-site search engine on the Web site of Dalsa (Waterloo, Ont., Canada) brings you to technical papers that describe the differences between CCD and CMOS imagers in terms of technology and potential applications. Of particular interest is an interview-style paper that concludes that for machine vision and web-inspection applications, cameras based on CCD technology are still the imagers of choice.
CCDs and night vision
Brooke Clarke's Web site contains information about CCD and CMOS cameras, night-vision devices, scientific CCD cameras, frame grabbers, and software. Clarke references specific devices with Hotlinks so that readers can access technical data from independent manufacturers.
PixelVision (Tigard, OR) manufactures CCD-based digital imaging systems for the scientific, medical, industrial, and surveillance markets. In addition to describing the company's products, this site contains a number of technical papers that describe the types of imagers now available, their performance characteristics, and systems design and image-quality issues. As well, there are descriptions of applications including thermal imaging, astronomy, and confocal imaging, with links to cameras that can be used in such applications.
Alireza Moini's book, Vision Chips or Seeing Silicon, was developed at the department of electrical and electronics engineering of the University of Adelaide (Adelaide, Australia) three years ago. This lengthy work is invaluable for anyone wishing to study imaging devices. With descriptions of nearly every device ever developed, this site includes information and comparisons on devices ranging from Carver Mead's silicon retina to logarithmic sensors using MOS diodes.
CMOS vs. CCD
Established by IMEC in December 1999 as a spin-off, FillFactory (Mechelen, Belgium) develops and markets CMOS image sensors. On the company's site there are a number of technical papers that describe the fundamental and technological performance of these devices as well as a well-documented FAQ section. Here, too, you'll discover how such devices can be used in high-resolution digital photography and high-speed imaging.