Abstract There is disclosed a photoelectric intrusion detector comprising a transmitter unit and a receiver unit. Each unit includes a collimating lens and a mirror adjustable about two axes of rotation. The detector employs an infrared beam invisible to the human eye and the mirror of each unit is positioned behind a dark red window, making it extremely difficult to ascertain beam direction. Jamming of the system is prevented by utilizing a pulsed, rather than a steady, beam. This also makes the system substantially insensitive to ambient light. There is also disclosed means for rapid alignment upon installation by method of an external visible light source attachable to each unit in turn, followed by adjustment of the mirror of the other unit.
The method of aligning an optical intrusion detector system including a transmitting unit having an invisible radiation source, an adjustable transmitting mirror and a collimating lens, a receiving unit having an adjustable receiving mirror, a photosensitive receiver and a focusing lens, and an auxiliary visible light source, which comprises: manually positioning said visible light source adjacent one of said transmitting and receiving units; adjusting the mirror of the other of said units to focus visible light from said light source through its corresponding lens onto its corresponding source or receiver; manually repositioning said visible light source adjacent the other of said transmitting and receiving units; and adjusting the mirror of said one unit to focus visible light from said light source through its corresponding lens onto its corresponding source or receiver.
Claim 2
Independent Claim
131 words
The method of aligning an optical intrusion detector system including a transmitting unit having an invisible radiation source, an adjustable transmitting mirror and a collimating lens, a receiving unit having an adjustable receiving mirror, a photosensitive receiver and a focusing lens, and an auxiliary visible light source, which comprises: manually positioning said visible light source adjacent one of said transmitting and receiving units; adjusting the mirror of the other of said units to focus visible light from said light source through its corresponding lens onto its corresponding source or receiver; manually repositioning said visible light source adjacent the other of said transmitting and receiving units; and adjusting the mirror of said one unit to focus visible light from said light source through its corresponding lens onto its corresponding source or receiver.