Passive vehicle presence detection system

In a passive optical system for use in detecting the presence of one or more objects in an area of surveillance, comprising

• a tubular sensing member arranged with its longitudinal axis directed to the area of surveillance in which the object may intrude, said sensor member having a light sensitive device including at least one light sensitive cell mounted interiorly thereof at one end and being adapted for sensing the light variations of light rays entering and projecting through said member in response to light variations produced between light rays emanating from one or more target vehicles intruding into the area of surveillance and the light rays emanating from the ambient light conditions adjacent or within the area of surveillance, said member being adapted to produce a signal in accordance with variations thereof, said member also being formed with means for directing and focusing light rays emanating from the area of surveillance through said tubular member and upon said at least one light sensitive cell, and a second sensor member arranged for sensing the ambient light conditions within the area of surveillance.

A passive optical system for use in a host aircraft for detecting the presence of one or more aircraft in airspace under surveillance, comprising

• a plurality of sensing tubes, each being arranged with its longitudinal axis directed to a predetermined portion of the air-space under surveillance in which an aircraft may intrude, each of said sensor tubes having a light sensitive device including at least one light sensitive cell mounted interiorly thereof at one end and being adapted for sensing light variations of light rays entering and projecting through said tube in response to light variations produced between light rays emanating from one or more target aircraft intruding into the airspace under surveillance and the light rays emanating from the ambient light conditions within the airspace under surveillance, said tubes being adapted to produce a signal in accordance with said light variations thereon, each of said tubes also being formed with means for directing and focusing light rays emanating from their respective portions of the airspace under surveillance upon said at least one light sensitive cell, said means for directing and focusing including a lens device prefocused to a predetermined distance into its respective portion of the airspace.

In a passive optical system for use in a host vehicle for detecting the presence of one or more target vehicles in an area of surveillance, comprising

• at least one cylindrical sensor member mounted on the host vehicle and arranged with its longitudinal axis directed to the area of surveillance in which the target vehicle may intrude, said sensor member having a light sensitive device including at least one light sensitive cell mounted interiorly thereof at one end and being adapted for sensing the light variations of light rays entering said member in response to one or more target vehicles intruding into the area of surveillance, said cell being adapted for producing a signal in accordance with variations thereof and therefore the presence of one or more target vehicles, said member also being formed with means for directing and focusing light rays emanating from the area of surveillance upon said at least one light sensitive cell, said light sensitive including a linear array of cells and the passive optical system including a control system operatively connected to said cells, said control system being arranged to deactivate the cells at one end of sid array and activate the cells at the other end thereof when the host vehicle is turning along a curve of a roadway.