CCD stands for a charge-coupled device, which was first invented in the late 1960s. CCDs are used to capture and store images in a digital memory, and they have proved to be vitally important in many areas of science and technology. CCDs allow the use of photocopiers, fax machines, security surveillance, mammography, dentistry X-rays, cameras and camcorders. Most digital cameras today contain a CCD image sensor to capture and store digital prints. Recently, the most popular use of CCD cameras is for astronomical research.
Charge-coupled devices (CCDs) were invented by Willard Boyle and George E. Smith at Bell Labs in 1969. Originally, Boyle and Smith considered this invention as a new type of computer memory circuit. The circuit is charged by light, and because of its silicon finish, the CCDs are very light sensitive. With this realization, Boyle and Smith knew that CCDs could capture better images if placed inside a camera. The more light that is collected, the clearer and more precise an image will appear. When digital cameras emerged, CCD image sensors were placed inside of them to capture light.
How They Work
Instead of film, most digital cameras house a CCD image sensor. When light is collected inside the camera and placed onto the silicon finish, this image sensor converts that light into electrical charges, or electrons, which allow the light to become digital images. In the most basic sense, Kodak's Technical Overview describes the process as the camera's shutter opening, the silicon CCD exposed to light, this light converted into electrons, the electrons converted into a digitized signal, and this signal captured as a memory and displayed on the camera's screen.
All CCD cameras provide high-quality, low-noise images with light sensitivity and a high number of pixels. All digital cameras measure light in red, green and blue hues, but the quality of the images depends on the quality of the camera you purchase. CCD cameras contain one to three CCD arrays. One CCD array deciphers all three hues, making it more difficult to separate each hue from the other. Cameras with one CCD array are usually used for security surveillance or other uses where precise color isn't necessary. Cameras with three CCD arrays provide one array for each hue, allowing more precision in the final outcome.
Although most digital cameras contain a CCD image sensor, high-tech CCD cameras are popular in life science and astrophotography use and are even used in the Hubble Telescope. CCD cameras allow long exposure times when capturing an image in a telescope. The camera replaces the eyepiece of a telescope, and it connects to a computer. Exposures are completed in seconds, they capture a great range of brightness and they can merge many images into one. CCD cameras respond to up to 70 percent of available light, compared to the 2 percent that traditional cameras capture in the night sky. Because these cameras are much more advanced, the cost ranges from $500 to $10,000.
Purchasing a CCD Camera
What type of CCD camera you purchase depends on how you plan to use it. For attaching to a telescope or microscope, purchase a CCD camera made specifically for that purpose, a c-mount or a t-mount adaptor to attach the camera to the telescope or microscope eyepiece, and an adaptor to connect the camera to a computer. If you just want a traditional camera that creates high-quality images, look for a digital camera that contains a CCD image sensor. Video cameras, webcams and video surveillance cameras are also available with CCDs.