Retroreflector-based system and method for detecting intrusion into a restricted area

A system for detecting entry of an object from a first area to a second area comprising:

• a linear array of individual light sources for generating a plurality of light beams, said light beams forming a light plane separating said first area from said second area;
• a retroreflector positioned across from said linear array of individual light sources, said retroreflector for reflecting said plurality of light beams back to said individual light sources;
• a plurality of photodetectors positioned adjacent to said light sources, said photodetectors for detecting said light beams after reflection;
• and
• a processor coupled to said plurality of photodetector for generating a signal in response to one of said plurality of photodetector detecting an interruption in one of said plurality of light beams.

A method for detecting entry of an object from a first area to a second area comprising:

• generating a plurality of light beams at a plurality of light sources, said light beams forming a light plane separating said first area from said second area;
• reflecting said plurality of light beams back to said individual light sources by a retroreflector positioned across from said linear array of individual light sources;
• detecting said light beams after reflection at a plurality of photodetectors positioned adjacent to said light sources;
• detecting an interruption in one of said plurality of light beams;
• and
• generating an alarm signal in response to said interruption.