ABSTRACT
This chapter introduces the analytic signal to discuss non-chromatic waves. The analytic signal is a complex signal, of which imaginary part is given by the Hilbert transform of its real part. The Hilbert transform has its inverse transform. An application of the Hilbert transform to interference fringe analysis is described. The use of the complex representation of a real monochromatic sinusoidal wave has been mentioned, and its usability is emphasized. Even for non-monochromatic light, it is convenient to use the complex representation so that the real part of the complex representation of complex signal can give real amplitude of light wave. In linear operations, the wave in a complex form is used in the calculation process and the real part of the final result of the operation gives the physically existing wave.
