Microscopy Primer
Light and Color
Microscope Basics
Special Techniques
Digital Imaging
Confocal Microscopy
Live-Cell Imaging
Microscopy Museum
Virtual Microscopy
Web Resources
License Info
Image Use
Custom Photos
Site Info
Contact Us

The Galleries:

Photo Gallery
Silicon Zoo
Chip Shots
DNA Gallery
Amino Acids
Religion Collection
Cocktail Collection
Screen Savers
Win Wallpaper
Mac Wallpaper
Movie Gallery

Interactive Tutorials

Full-Frame CCD Operation

Full-frame charge-coupled devices (CCDs) feature high-density pixel arrays capable of producing digital images with the highest resolution currently available. This popular CCD architecture has been widely adopted due to the simple design, reliability, and ease of fabrication. Instructions for operation of the tutorial appear beneath the applet window.

The pixel array illustrated in the full-frame CCD above consists of a parallel shift register, onto which images are optically projected by means of a camera lens or microscope optical train. In this configuration, all of the photodiodes in the pixel array collectively act as the image plane and are available for detecting photons during the exposure period. This is illustrated in the tutorial as the area in which the image slowly formed. The speed in which the CCD collects image data is adjustable with the Image Acquisition Delay slider. A miniature portion of the total image is contained in each pixel element, which consists of four photodiodes masked with red, green, and blue colored filters. The image presented in the upper right-hand corner of the tutorial is an actual high-magnification photomicrograph of a single pixel element.

After photons composing the image have been collected by the pixel elements and converted into electrical potential, the CCD undergoes readout by shifting rows of image information in a parallel fashion, one row at a time, to the serial shift register (illustrated as a series of gray-scale elements at the bottom of the pixel array). The serial register then sequentially shifts each row of image information to an output amplifier as a serial data stream. This action is controlled by the CCD Speed slider in the tutorial. Use the mouse cursor to shift the slider to the left to observe the CCD at slower shift speeds, or to the right for faster speeds. The entire process is repeated until all rows of image data are transferred to the output amplifier and off the chip to a analog-to-digital signal converter integrated circuit. Reconstruction of the image in a digital format yields the final photograph or photomicrograph.

Full-frame CCD architecture has what is termed a 100 percent fill factor, meaning that the entire pixel array is used to detect incoming photons during exposure to the object being imaged. CCDs of this type typically have square pixel dimensions to avoid image distortion and are fabricated with pixel sizes ranging from 7 to 24 microns in arrays containing up to 6 million pixels. Due to the fact that the pixel array is used for both image detection and readout, a mechanical shutter or synchronized strobe illumination scheme must be used to prevent smearing for most exposure periods.

Contributing Authors

Mortimer Abramowitz - Olympus America, Inc., Two Corporate Center Drive., Melville, New York, 11747.

Matthew J. Parry-Hill and Michael W. Davidson - National High Magnetic Field Laboratory, 1800 East Paul Dirac Dr., The Florida State University, Tallahassee, Florida, 32310.


Questions or comments? Send us an email.
© 1998-2022 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.
This website is maintained by our
Graphics & Web Programming Team
in collaboration with Optical Microscopy at the
National High Magnetic Field Laboratory.
Last modification: Thursday, Feb 11, 2016 at 11:14 AM
Access Count Since June 8, 2000: 125481
Visit the websites of our partners in digital imaging education:
Visit the Olympus Microscopy Resource Center website. Visit the QImaging website.