Self-derived reference beam holography using a dove prism

A system for use in recordation and recognition of signal information from such signals as acoustical waves, electromagnetic waves and like signals capable of being used to modulate light, comprising:

• a source of light radiation;
• receiving means for receiving desired signal information;
• modulating means adapted to receive the light provided by said light radiation source, said modulating means adapted to modulate at least a portion of light from said light source in accordance with the desired signal information to be recorded or recognized;
• optical means for allowing only modulated light radiation to be transmitted thereby;
• beam-splitting means for splitting said modulated object beam into a signal and a corresponding self-derived reference beam, said beam-splitting means including:
• a first transparent prism element having a first essentially flat incident surface, a first base surface and a first exit surface, the index of refraction of said first prism and the orientation of said first incident surface with respect to said base surface and object beam being selected to refract the object beam, when incident on said first incident surface, towards said first base surface whereat the once refracted object beam in part is reflected towards said first exit surface which is oriented to refract the reflected beam portion towards a predetermined plane to form said signal beam and in part is transmitted through said first base surface, said first prism comprising an isoselese trapezoidal dove prism having equal base angles along said first base surface;
• and
• a second transparent prism having a second base surface abutting said first base surface and a second exit surface, said second base surface and said second exit surface forming an angle smaller than the base angle of said first prism element, the interface of said first and second base surfaces being adapted to split the object signal beam into the reflected beam portion which is reflected towards said first exit surface and a transmitted beam portion which is transmitted into said second prism, the index of refraction of said second prism and the orientation of said second exit surface relative to said second base surface being selected to refract the transmitted beam portion towards said second exit surface which in turn refracts the transmitted beam portion towards the path of the signal beam to form said reference beam and to interfere optically with the signal beam at the predetermined plane, said first and second prisms being coupled together to form an essentially integral beam-splitting means which is virtually unaffected by mechanical vibrations;
• and
• a photo-optical element positioned essentially at the location of optical interference between said signal and reference beams.