Radiant energy – Radiant energy generation and sources – Plural radiation sources
Reexamination Certificate
2001-06-25
2004-10-19
Nguyen, Judy (Department: 2861)
Radiant energy
Radiant energy generation and sources
Plural radiation sources
Reexamination Certificate
active
06806480
ABSTRACT:
FIELD OF THE INVENTION
The present invention refers to targets devices used for simulating of various military and civilian objects, like armored fighting vehicles, battle tanks, armored personnel carriers, military and civilian vehicles. The invention also refers to identification and marking means used for identification of those objects.
The products of the invention are intended mainly but not solely for activities associated with improvement the combat effectiveness of military forces, e.g. gunnery training, friend or foe target recognition and identification training, battlefield simulating and other activities.
The present invention refers to multi-spectral products including targets and identification means capable to simulate both the thermal and visual detectable signatures of various military and civilian equipment and to allow its detection and recognition either in darkness or in the daytime.
BACKGROUND OF THE INVENTION
There are known various military targets, which have been devised for simulating of military assets and intended for use in so-called cover, concealment and deception (CC&D) activities.
The existing military targets used in CC&D activities can be divided into three groups according to the principle of their operation.
The first group includes military targets, which are detectable and recognizable during the day only. An example of such a target is inflatable target apparatus, disclosed in U.S. Pat. No. 4,505,481. This apparatus simulates battlefield and comprises an inflatable target mounted on a trolley. The inflated target is suitable for detection the passage of a projectile. The disadvantage of this group of targets, associated with their limitation strictly to daylight is self-evident.
The second group of targets includes so-called thermal targets, i.e. those, which are detectable and recognizable at night. These targets when heated emanate infrared radiation, known as object's thermal signature. A sighting device or so-called thermal image capable to detect infrared radiation at night or can see the thermal signature in conditions of obscured visibility.
The main disadvantage of these targets is associated with the fact, that they necessitate an external source of energy, capable to heat the target and to induce the infrared radiation. For the sake of brevity, such thermal targets will be referred-to further as active thermal targets.
An example of such active thermal target can be found in U.S. Pat. No. 5,065,032, disclosing thermal integrated target that produces and emits an infrared image for simulating heat emitting equipment or personnel. The image is formed when an electric current passes through a resistive coating applied to the target. This integrated target is intended for use at night only.
Another example of an active thermal target for night vision is described in U.S. Pat. No. 4,260,160. This thermal target is intended for practice shooting in darkness and it comprises a thin supple fabric supported on a rigid frame. The configuration of the fabric simulates the silhouette of an object at which firing would take place, e.g. a tank as seen from its front. The fabric comprises a front protective sheet and a rear radiation-absorbing sheet. The front sheet is held spaced and parallel from the fabric and thus a heat insulating space is defined between them. An infrared radiator heats the heat-absorbing sheet, which radiates as a black body. By virtue of this provision a heat radiation pattern is produced, which closely simulates the object. The disadvantage of this target is similar to that mentioned in connection with U.S. Pat. No. 5,065,032.
The third group includes active thermal targets, which can be used also during the daytime. Those targets are known as multi-spectral targets.
An example of such thermal target is disclosed in U.S. Pat. No. 5,599,023 referring to partially translucent mural decoy. This decoy contains selective translucent panels representing horizontal and other areas of the simulated target. By virtue of this provision, the target represents the object realistically during the day irrespective of the incidence of sunlight to the object. The decoy can be also provided with an auxiliary means for supplying warm air into a bag disposed on one said of the target. By virtue of this provision, the decoy appears warm under infrared observation and therefore is detectable at night.
Even more sophisticated multi-spectral active thermal target is disclosed in U.S. Pat. No. 4,422,646. In this patent, there is described infrared target for military applications. The target comprises a multiplicity of independent modules, each of modules corresponding to a thermal cue of a military object. Each module comprises flexible laminate capable of conducting an electric current, supplied from an external electrical power source. The top layer of the laminate is covered by a flexible, thermal insulating pad containing a multiplicity of discrete air-containing cells through which an infrared signal can pass. The modules are covered by visible graphics to depict the object in visible light and thus the visual signature of the military object is superimposed upon the thermal signature. Nevertheless, by virtue of the cells the thermal signature can be radiated and seen at night through the visual signature.
The active multi-spectral targets are good for recognition of a simulated object. Nevertheless, their sufficient intrinsic disadvantage is the necessity in an auxiliary source of heat energy, which should be sufficient for producing reliably detectable and recognizable thermal signature. Active targets require relatively large amount of electrical power, they are difficult to control, their construction is complicate and they are relatively expensive items.
There are also known so-called low emissivity thermal coatings, which exhibit very low emissivity in the thermal infrared band range. When such a coating covers some areas of an object, the intensity of the infrared radiation, emanated by the coated areas is much lower in comparison with the intensity of the infrared radiation emanated by the uncoated areas. This phenomenon allows using such coatings for thermal insulation applications, in particular for insulation curtains of windows.
Insulation products, based on low emissivity coatings are manufactured for example by Hanita Coatings, Israel. These products comprise sandwiched structure, consisting of several thin aluminum layers interspersing with polyester film layers. A low emissivity lacquer, having emissivity 0.22-0.29, coats the upper aluminum layer. Such sandwiched structure reflects more than 70% of the radiation in the several micron band ranges and provides reliable thermal insulation.
By virtue of low emissivity insulation coating a thermal contrast can be created, enabling detection and recognition within the IR specter of those areas, which were hidden by the coating. The hidden areas of an object will be seen in a thermal imager as “cool” regions, contrasting with the adjacent “hot ” regions, corresponding to the uncoated areas. It can be easily appreciated, that this thermal contrast can be induced without heating of an object and thus without the necessity to employ an external source of thermal energy.
The targets based on this approach include so-called passive or no-power targets and they refer to the fourth group. These targets are manufactured for example by Opticoat Associates Inc. U.S.A.
A target employing low-emissivity coating is disclosed in U.S. Pat. No. 3,986,384. This target is used for testing infrared sensors and provides a known spatial pattern such as a bar group. In order to provide a passive target, which is suitable for a range of thermal contrasts the target is formed as a sandwiched structure, consisting of three plane rigid members. The intermediate member is incrementally slidable between the front and rear member. The front member has a cutout, which exposes the intermediate member and the intermediate member has a perforated region in the area exposed by the cutout. The perforat
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