Phase gradient contrast microscope

Abstract

Apparatus and methods for producing an intensity image from a transparent phase object. A laser beam is generated and expanded. A shutter disposed in the path of the expanded laser beam is opened, and the expanded laser beam is split into first and second beams. The first beam is directed through the transparent phase object and focused into a photorefractive hologram recording crystal for the write time of the crystal. The shutter is closed, and the position of the transparent phase object is shifted an incremental amount. The shutter is opened again so that the first beam is directed through the shifted transparent phase object and into the photorefractive hologram recording crystal such that a phase-conjugate beam is produced traveling in the opposite direction of the first beam. The phase-conjugate beam is collimated, directed through the shifted transparent phase object, and split into third and fourth beams. The third beam is directed into the objective of a microscope to form an intensity image of the transparent phase object.