Overview It is beyond the scope of this presentation to cover all aspects of the applications of optical filters and combined filter/detector products. Therefore, the following notes will be somewhat limited to the more common aspects. The instrument designer will find a variety of books and articles available to offer further assistance in the pursuit of instrument design. In particular, we recommend Modern Optical Engineering by Warren J. Smith from McGraw-Hill. Any engineer designing instruments using optical filters will find chapters 7 and 8 of this book to be very informative. A good book on thin film technology is Thin-Film Optical Filters by H. A. MacLeod from American Elsevier Publishing Company. For Silicon detector circuitry, we recommend Photodetector Amplifiers by Jerald Graeme from McGraw Hill, it can usually be found in any good technical library. There are three major categories of filter and combined filter/detector usage: 1. Absorptance of energy in a transmitted path 2. Reflectance of energy from an object 3. The use of optical energy in data transfer This list does not represent all possible uses of filtered optical energy, merely a majority of applications. Other major factors to be considered in instrument design are the optical filter specifications, spectral distribution of the energy source, and the spectral distribution of the receiving element. All of these must be carefully evaluated for optimum instrument performance.