| 摘要 |
A conventional interferometer has been modified so that amplitude and phase information contained in an interference pattern may be calculated from intensities read out by a television camera and phase shifts introduced by rotation of a quarter-wave plate. To operate the device, reference light at a first phase is interfered on the television camera with light from the object being tested. Such an object might be a lens. The camera samples the intensity of the interference pattern at an array of points; and these values of intensity are stored in a computer. Next, a known phase shift is introduced into the reference beam by rotating the quarter-wave plate; and the intensity in the resulting interference fringe pattern is again sampled at the same points in the array and stored. This process is again repeated for a second known phase shift. Because the three values of intensity obtained at each point in the array are interrelated by the fact that the intensity at any point in the interferogram is a cosinusoidal function of phase, simultaneous solution at each point of three equations corresponding to the three values of intensity produces phase and amplitude plots of the wavefront from the object under study. Alternatively, by making several measurements of the intensity over phase angles from zero to 2 pi , it is possible to form phase and amplitude plots by determining Fourier coefficients.
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