Viewing of objects in low visibility atmospheres

• US 4,671,614 A
• Filed: 09/14/1984
• Issued: 06/09/1987
• Est. Priority Date: 09/14/1984
• Status: Expired due to Fees

• Current Assignee: Salvatore B. Catalano
• Original Assignee: Salvatore B. Catalano
• Inventors: Catalano, Salvatore B.
• Primary Examiner(s): NOT, DEFINED
• Application Number:
  US06/650,474
• Time in Patent Office: 998 Days
• Field of Search: 350/276 R
• US Class Current: 359/601
• CPC Class Codes: G02B 23/12 with means for image conversion or intensification
• CPC Class Codes: G02B 26/04 by periodically varying the intensity of light, e.g. using choppers shutters, diaphragms for cameras G03B9/00; devices for eliminating or reducing the effect of flicker in projection systems G03B21/40

Abstract

A viewing system for use in low visibility atmospheres, such as fog, rain, snow, dust, smoke, etc., particularly under nighttime conditions. A cyclically-operated pulsed light source illuminates the scene for brief instances. A shutter is operated in synchronism with the light source for transmitting to a human observer (or TV camera) light rays reflected from objects located selected distance intervals away from the light source; light rays from other zones or areas are excluded. By thus excluding light reflections from zones outside the selected distance interval, it should be possible to minimize glare associated with the excluded light, thereby improving the view of objects located within the selected distance interval. The viewing system may include mechanisms for varying the time relationships between the pulsed light source and shutter, such that different selected distance intervals are viewed in continuous progression; the different views are flashed very rapidly so that the human observer or TV camera effectively sees objects in various different distance intervals, e.g., the entire range distance of the light source.

Claims

1. A system for viewing target objects in a low visibility atmosphere containing significant particulate matter in the form of fog, snow, rain, dust or smoke, where atmospheric glare due to backscattered light tends to unduly limit the distance at which target objects are visible:

said system comprising a light pulse source operable to direct time-spaced outgoing light pulses (10) of a required intensity through a multiplicity of non-overlapping contiguous distance intervals;

a viewer station comprising a shutter device operable to receive light rays reflected from objects located in said distance intervals;

means for controlling the shutter device so that at any one shutter-open period, the device passes a reflected light pulse (12) from only one distance interval; and

sequencing means for causing the shutter device to sequentially pass light pulses from different distance intervals;

said sequencing means being operable so that a given sequence takes place as a progression from the distance interval nearest the shutter device to the distance interval furthest from the shutter device, without significant delay between any given reflected light pulse (12) and the next outgoing light pulse (10);

the sequence of shutter operations being repeatable without interruption, whereby the shutter device effectively presents to the viewer the entire scene encompassed by the contiguous distance intervals;

each light pulse having a duration time 2d/10c and the shutter device having an open duration time 2d/c, where d is the width of a distance interval, and c is the speed of light;

the delay time between each light pulse and the instant of shutter opening being approximately n 2d/c, where n is the number of distance intervals between the viewer station and the distance interval exposed when the shutter opens;

said light source having a pulse duration time of about 0.1 microsecond, and the shutter device having a shutter-open time of about 1 microsecond, such that the light source pulse duration time is only about one tenth the shutter-open time.