Charged Coupled Device

A charge coupled device (CCD) is an integrated circuit etched onto a silicon surface forming light sensitive elements called pixels. Photons incident on this surface generate charge that can be read by electronics and turned into a digital copy of the light patterns falling on the device. CCDs come in a wide variety of sizes and types and are used in many applications from cell phone cameras to high-end scientific applications.

The function of a CCD can be visualized as an array of buckets(pixels) collecting rainwater (photons). Each bucket in the array is exposed for the same amount of time to the rain. The buckets fill up with a varying amount of water, and the CCD is then read one bucket at a time. This process is initiated by pouring water into the adjacent empty column. The buckets in this column transfer their ‘water’ down to a final pixel where the electronics of the camera read-out this pixel (the computer measuring the bucket) and turn it into a number that can be understood and stored by a computer.

CCDs are sensors used in digital cameras and video cameras to record still and moving images. The CCD captures light and converts it to digital data that is recorded by the camera. For this reason, a CCD is often considered the digital version of film. The quality of an image captured by a CCD depends on the resolution of the sensor. In digital cameras, the resolution is measured in Megapixels (or thousands of or pixels. Therefore, an 8MP digital camera can capture twice as much information as a 4MP camera. The result is a larger photo with more detail.

CCDs in video cameras are usually measured by physical size. For example, most consumer digital cameras use a CCD around 1/6 or 1/5 of an inch in size. More expensive cameras may have CCDs 1/3 of an inch in size or larger. The larger the sensor, the more light it can capture, meaning it will produce better video in low light settings. Professional digital video cameras often have three sensors, referred to as "3CCD," which use separate CCDs for capturing red, green, and blue hues.