The CCD: a quantum leap

In a book on the nature of scientific discovery science historian Gerald Hawkins notes that recent centuries of human endeavour show a highly significant pattern. Our perception of the Universe tends to evolve, not in a steady upward curve, but on a generally level line that periodically takes a sudden step upward.

Quantum leaps in knowledge, Hawkins points out, invariably follow the introduction of radically new observational tools. Thus, a revelatory new view of deep space was the immediate result of the invention of astronomical photography in the mid-nineteenth century. Photographic emulsions were able to accumulate an image during a long exposure and some emulsions were sensitive to wavelengths never seen by the human eye. A new Cosmos of nebulae and intricately structured galaxies was suddenly accessible.

In recent years a similar leap forward has occurred, in the introduction of the CCD camera, an electronic innovation that has expanded the horizons of first the professional astronomer and then, almost immediately, the amateur as well.

The CCD camera

The charge coupled device (CCD) is an electronic camera designed to capture light and, in conjunction with a computer, to produce an image. The heart of the CCD is a silicon chip with thousands of light-sensitive sites called pixels. Each pixel converts incoming photons of light into electrons, which are stored in the pixel.