Linear phase microscopy.

A technique is described for measuring the phase of complex transmitting objects. It consists of two basic parts. The first is an optical system that imposes the phase of an object onto a sinusoidal carrier in the form of a phase modulation. This is accomplished using interferometric and optical heterodyning techniques. The second is a phase detection system that converts this phase modulation into a signal that is directly proportional to the phase of the object. This technique measures phase variations from zero to 167pi, (2pi ambiguities are avoided) with a spatial resolution of 600 cycles/mm and a phase resolution of 2pi/100. Analysis of this technique and experimental results are given.