Radiant energy – Photocells; circuits and apparatus – Photocell controls its own optical systems
Reexamination Certificate
2000-01-28
2002-10-01
Allen, Stephone (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
Photocell controls its own optical systems
C250S208100, C348S122000, C472S061000
Reexamination Certificate
active
06459076
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates to camouflage. More particularly, the present invention relates to reactive camouflage. Still more particularly the present invention relates to a method and system for disguising an object using reactive camouflage.
2. Description of Related Art
During World War II, allied torpedo bomber aircraft were assigned the task of hunting and sinking German submarines on the surface of the open ocean. The bombers were largely unsuccessful because submarine lookouts could see the bombers from a distance, silhouetted against a bright sky, allowing the submarines ample time to dive to safety. An allied invention using one element contained in the present invention was used to greatly increase the number of German submarines that were sunk by torpedo bombers. A row of simple incandescent lights was placed on the leading edge of the wing of the torpedo bombers to fill in the forward-facing silhouette of the torpedo bomber with light. After this invention was implemented, German submarine captains reported that they could hear the engines of the torpedo bomber before they could see it.
In order to camouflage an object to blend with its background when viewed by the human eye, it is generally accepted that the contrast between the object and its background must be reduced. In order to reduce the contrast, the color and intensity of the light coming from the object toward the viewer's eye must simulate the color and intensity of the light coming toward the viewer's eye from the background immediately behind the object. Most methods of camouflage vary the shape, texture and surface color of an object in order to make it reflect light in such a manner that the viewer sees a color and intensity of reflected light (also known as diffuse reflection and/or specular reflection) similar to the object's background. Traditional camouflaging techniques provide passive color shading and, therefore, cannot react to changing backgrounds which silhouette a moving object. Furthermore, passive camouflage cannot fill in light, which has been blocked by the object, or increase lighting levels when the object is less radiant than its background.
Another, potentially serious problem with current camouflage techniques is that a camouflaged object has approximately the same color shading from any angle. This is a critical flaw for a moving object that gives observers different views of the object against different backgrounds. While an object may be obscured from one observer by its camouflage pattern, a second observer from a second vantage point might distinguish the object against a different background with different lighting conditions, even though the two observers are roughly equal distances from the object.
It is important to understand that, in many regional conflicts, the weaponry utilized by the adversaries is less technologically advanced. Most regional armies rely upon weapons that require visual acquisition of a target. These weapons are generally less effective at longer ranges, so the longer it takes for an advisory to detect an object and identify the object as a threat, the less chance that the advisory can bring weapons to bear on the object before it moves out of range.
It would be advantageous to provide an object with a camouflage that matches the lighting intensity of the object's background by actively generating such intensity of light as may be appropriate to the object's background. It would also be advantageous to provide an object with a camouflage, which varies in color and intensity with the viewpoint from which an observer views the object, providing simultaneously differing images in differing directions. It would also be advantageous to provide an object with a camouflage which utilizes its capability of projecting simultaneously differing images in differing directions to vary in color and intensity with varying background changes as the object moves from one position to another with respect to the observer. It would be further advantageous to utilize such advanced projection techniques to create an image that is intentionally visible, but which creates an illusion to mimic some other object.
SUMMARY OF THE INVENTION
In accordance with an illustrative embodiment of the present invention, a camouflage system comprises variable light transmitters covering the surface of an object, which are used to blend the object with its background, making it difficult to visually distinguish from its background. Variable light transmitters covering an object are each individually controlled by a controller, which varies the light color and intensity coming from the light transmitters. In order to blend the object with its background, light sensors are placed on the opposite sides of the object, and paired through a controller or controllers to individual light transmitters. Each light sensor senses the color and intensity of light coming from one side of an object, and a controller uses this information to vary the color and intensity of light transmitted from a paired light transmitter on the opposite side of the object, exactly matching the color and intensity of background light. For example, if a viewer sees the object against a bright blue sky, the light transmitters covering the object which are facing the viewer would be transmitting bright blue light to match the background light as sensed by paired sensors on the opposite side.
Note that “color and intensity” of light in the description of the present invention means the specular power distribution, luminance, and other specular characteristics of light. Note also that the matching of colors in the present invention is metameric color matching, meaning that the simulated colors need not have specular characteristics identical in every way to the original color, but need only appear to the human eye to be a perfect match because of the limited range of color sensitivity in the human eye and other psychophysical and psychological factors.
In some applications a viewer may view the object from an oblique angle, seeing the object against different background light than would be seen if viewed from a “straight on” view at a right angle to the surface of the object. In order to allow for camouflage from oblique views, light sensors and transmitters are designed to be directional and are designed to receive or transmit light at varying angles. Each light transmitter transmits light rays outward essentially parallel to a single axis. Transmission of light outward from light transmitters that do not create diffuse light, but transmit light in a narrow dispersion of nearly parallel light rays, can be accomplished with a variety of existing technologies. For example, light sources can be equipped with lenses or view limiting devices so that only nearly parallel light rays are emitted from individual light transmitters, and light can only be viewed by viewers directly in line with a light transmitter's aiming path. Light sensors are similarly fitted with lenses or view limiting devices so that light is only sensed from sources directly in line with the aiming path of each sensor. A light transmitter with an aiming path that is at a right angle to the surface of the camouflaged object is varied by a controller to match light measured by sensors on the same aiming axis as the transmitter but with an aiming path pointed in the exact opposite direction on the opposite side of the object. Light transmitters with an aiming path that is at an oblique angle to the object would be varied by a controller to match light measured by sensors on the same axis as the transmitter, but with an aiming path pointed in exactly the opposite direction. Light transmitters with aiming paths at a variety of angles are interspersed in close proximity to each other on the surface of the object so that transmitted light originating from all parts of the surface of the object would be visible to a viewer from any perpendicular or oblique viewing angle, without any “blank
Allen Stephone
Hill Bradford
Holmes Patrick
Yee Duke W.
LandOfFree
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