This is essentially the optical element of a digital scanner or camera. You will find them in every camera phone or web cam.
They are essentially an exposed portion of a chip made with the same fabrication techniques used to mass produce most of the other integrated chips in the rest of the device carrying them. This what has made them so cheap. The exposed portion is an array of capacitors which are sensitive to light, and linked together.
For those experimenting with robot vision, a salvaged old EPROM chip with the UV cover removed may actually present an image across its pins, although webcams and camera phone elements are now becoming so cheap that it may not be necessary. However, the camera phone CCD element may be surface mounted to the phones control board, thus making it virtually impossible to remove and reuse without destroying it.