Holographic imaging

An apparatus for imaging an object obscured by a diffusing medium, comprising:

• a pulsed laser light source to generate an object beam (3') and a reference beam (4') whereby the object (7) obscured by the diffusing medium can be illuminated with the object beam (3');
• a real time interferogram recording medium (8), comprising a photorefractive medium, arranged to be exposed to, and to record an interferogram formed by the coincidence of light from the object (7) and the reference beam (4');
• a means for reconstructing an image from the interferogram;
• and
• a means for recording the image;
• wherein said apparatus includes a reference beam path means for guiding the reference beam so that a pulse of the reference beam arrives at the real time interferogram recording medium so as to be coincident with at lease one of unscattered light and least scattered light from the object, thereby causing the interferogram recorded to represent the information content contained within the unscattered light or the least scattered light from the object (7);
• and
• wherein the object and reference beams (3, 3'), (4, 4') impinge upon the recording medium (8) substantially parallel to each other and the reference beam (4, 4') passes through an adjustable delay line assembly (14) whereby the length of the path followed by the reference beam (4, 4') can be adjusted.

A method of imaging an object obscured by a diffusing medium, the method comprising:

• employing a pulsed laser light source to generate an object beam (3') and a reference beam (4') whereby the object (7) obscured by the diffusing medium can be illuminated with the object beam (3');
• recording on a real time interferogram recording medium (8) comprising a photorefractive medium, an interferogram formed by the coincidence of light from the object (7) and the reference beam (4');
• guiding the reference beam so that a pulse of the reference beam arrives at the real time interferogram recording medium so as to be coincident with at least one of unscattered light and least scattered light from the object, thereby causing the interferogram recorded to represent the information content contained within the unscattered light or the least scattered light from the object (7);
• reconstructing an image from the interferogram;
• and
• recording the image.