Method and apparatus for producing a holographic shadowgram

An apparatus for producing a holographic shadowgram of an object, the apparatus comprising:

• light source means for generating a coherent light beam;
• reflector means for reflecting the coherent light beam to simultaneously produce a diffuse object beam and a coherent reference beam such that differential vibration between the object and reference beams is substantially eliminated, and for back illuminating the object with the object beam such that the object and reference beams create a substantially stable interference pattern, the reflector means comprising a rigid board having a reflective surface, the reflective surface having a diffuse portion and a non-diffuse portion wherein the diffuse portion reflects the coherent light beam to produce the diffuse object beam and the non-diffuse portion reflects the coherent light beam to produce the coherent reference beam;
• and
• recorder means for recording the interference pattern of the object and reference beams to produce the holographic shadowgram.