Object detection method and apparatus employing electro-optics
US4926170A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 12, 1987 |
| Grant date | May 15, 1990 |
| Priority date | — |
| Expiry date | Feb 12, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01S2007/4975
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Apparatus for detecting the presence of an object within an area under surveillance employs an electro-optical emitter for directing light into the area and an electro-optical receiver for sensing light reflected from the object which originates from the emitter. The emitter emits light energy of a preselected wavelength and is modulated at a preselected frequency to provide the emanating light energy with a characteristic signature. Light reflected by an object within the area under surveillance is filtered and converted to an electrical signal which varies in accordance with the magnitude of the filtered light having the preselected wavelength and modulation frequency. A selected portion of the electrical signal is amplified by a band-pass amplifier and is synchronously sampled in accordance with the modulation frequency to determine the magnitude of the filtered light which originated from the emitter. The sampled signal is compared with a threshold value to determine whether an object is present within the area under surveillance. The emitter and receiver are covered by a transparent shield to protect them against foreign matter. An electro-optic detector monitors the accumulat…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.