Abstract

Imaging of phase objects can be divided into two cases: For large phase-changed objects, Topler invented a phase-to-amplitude conversion technique based on geometric optics using incoherent light—the so-called schlieren method. For small objects, Zernike invented a phase contrast method based on diffraction theory that used coherent light. However, for an acoustic standing wavefront the phase contrast method is not satisfactory; we did not pursue the reason.

© 1987 Optical Society of America