Optical Imaging and Spectroscopy

DETECTION

Despite the wide variety of applications, all digital electronic cameras have the same basic functions:

1. Optical collection of photons (i.e., a lens)
2. Wavelength discrimination of photons (i.e., filters)
3. A detector for conversion of photons to electrons (e.g., a photodiode)
4. A method to read out the detectors [e.g., a charge-coupled device (CCD)]
5. Timing, control, and drive electronics for the sensor
6. Signal processing electronics for correlated double sampling, color processing, and so on
7. Analog-to-digital conversion
8. Interface electronics

—E. R. Fossum [78]

5.1 THE OPTOELECTRONIC INTERFACE

This text focuses on just the first two of the digital electronic camera components named by Professor Fossum. Given that we are starting Chapter 5 and have several chapters yet to go, we might want to expand optical systems in more than two levels. In an image processing text, on the other hand, the list might be (1) optics, (2) optoelectronics, and (3–8) detailing signal conditioning and estimation steps. Whatever one's bias, however, it helps for optical, electronic, and signal processing engineers to be aware of the critical issues of each major system component. This chapter accordingly explores electronic transduction of optical signals.

We are, unfortunately, able to consider only components 3 and 4 of Professor Fossum's list before referring the interested reader to specialized ...