The principles of diffraction developed in preceding chapters were utilized in Chapter 3 to determine the diffracted field resulting from an array of similar diffracting apertures. This approach will lead naturally into the principles of interference, which are fundamentally important phenomena observed and utilized in physical optics. In essence, classical interferometry has been a very useful tool because of its ability to measure the relative phase of a wavefront by comparison to a calibrated reference wavefront. Table 22.I illustrates a small part of the myriad of applications for classical interferometry.
There are two general methods of creating beams of light that will interfere, and these provide a basis for classifying interference into two types. In one method, the beam is divided by passage through apertures placed side by side. This method is called division of wavefront. In the second method, the beam is divided at one or more partially reflecting surfaces into two or more wavefronts. This method is called division of amplitude. In this case, the two original wavefronts have the same width but reduced amplitudes.
In Chapters 22 through 24 we will discuss both types of interferometers and illustrate their utility in various applications.
Online access to SPIE eBooks is limited to subscribing institutions.