Optical laser security system
First Claim
1. A security system for giving an alarm when an intruder in a protected area interrupts a laser beam of light, said system comprisinga modulated laser which emits a continuous modulated beam of coherent light,a signal generator which modulates the said laser,a photo-electric light detector which transforms the light emitted by the laser to electronic signals,a dual operational amplifier which transmits the output of the signal generator both to the laser and to a Compare circuit,said Compare circuit also connected to the output of the photo-electric light detector circuit so as to compare the signal received by the said light detector circuit from the laser beam, with the laser modulation signal produced by the signal generator, andalarm triggering means connected to the Compare circuit, which means are energized when the Compare circuit distinguishes a difference between the signal produced by the signal generator and the signal received through the photo-electric light detector, in whichthe signal generator is a random noise generator connected to a Schmitt Trigger circuit, which Schmitt Trigger circuit converts the output of said random noise generator into digital pulses.
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Abstract
An optical laser is operated in a continuous mode and modulated by a random noise generator. The laser beam is split into parallel beams which are reflected throughout the area by mirrors and each directed into a photo sensitive electronic receptor circuit which electronically combines the output signals of the parallel beams of laser light. The combined output is electronically compared with the signal employed to modulate the laser beams, with an alarm circuit triggered when any difference is detected between the output signal generated by the laser beams and the input modulating signal.
24 Citations
2 Claims
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1. A security system for giving an alarm when an intruder in a protected area interrupts a laser beam of light, said system comprising
a modulated laser which emits a continuous modulated beam of coherent light, a signal generator which modulates the said laser, a photo-electric light detector which transforms the light emitted by the laser to electronic signals, a dual operational amplifier which transmits the output of the signal generator both to the laser and to a Compare circuit, said Compare circuit also connected to the output of the photo-electric light detector circuit so as to compare the signal received by the said light detector circuit from the laser beam, with the laser modulation signal produced by the signal generator, and alarm triggering means connected to the Compare circuit, which means are energized when the Compare circuit distinguishes a difference between the signal produced by the signal generator and the signal received through the photo-electric light detector, in which the signal generator is a random noise generator connected to a Schmitt Trigger circuit, which Schmitt Trigger circuit converts the output of said random noise generator into digital pulses.
Specification
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- Resources
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Current AssigneeThe Raymond Lee Organization, Inc.
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Original AssigneeThe Raymond Lee Organization, Inc.
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InventorsTodeschini, David John
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Primary Examiner(s)Swann, III, Glen R.
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Application NumberUS05/587,308Time in Patent Office491 DaysField of Search340/258 B, 340/258 D, 340/280, 340/276, 250/578, 250/221, 250/199, 332/9 R, 332/9 TUS Class Current340/557CPC Class CodesG08B 13/184 using radiation reflectors
