Under conditions where a CCD is exposed to very high intensity illumination, it is possible to exhaust the storage capacity of the CCD wells, a condition known as blooming. When this occurs, excess charge will overflow into adjacent CCD photodiode wells resulting in a corrupted image near the blooming site. This tutorial explores the operation of a lateral overflow drain to prevent CCD blooming.

	Interactive Java Tutorial
ATTENTION Our servers have detected that your web browser does not have the Java Virtual Machine installed or it is not functioning properly. Please install this software in order to view our interactive Java tutorials. Visitors using the Netscape and Microsoft Internet Explorer browsers can download the appropriate software from the websites where the browsers are distributed. Please do not contact us for information about specific URLs where this software can be obtained.

A common CCD anti-blooming technique involves "overflow" drain structures that are incorporated into the CCD during fabrication. Two of the most common drain structures are the vertical overflow drain (VOD) and the lateral overflow drain (LOD), illustrated above. Drains enable integration time to be controlled independently of charge readout, which allows them to serve as an electronic exposure or shutter mechanism to limit pixel saturation and provide a more reliable shuttering method than is currently possible with mechanical devices.

When the tutorial initializes, two sliders appear that control photon wavelength (color) and illumination intensity. Use the Photon Intensity slider to adjust the number of photons striking the CCD during a unit time period. The Illumination Wavelength slider can be used to control the wavelength of incoming photons.