Thermal Radiation Marker With Thin Enclosure
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Solution Overview
Problem
Existing thermal markers operating in the midwave-infrared and longwave-infrared spectrum bands face challenges in achieving high temperature stability and covert visibility, with current solutions either being inefficient in energy conversion or visible to unauthorized observers.
Innovation Solution
A thermal radiation marker utilizing a thin glass or quartz enclosure filled with pressurized inert gas and an incandescent filament, capable of reaching temperatures beyond 2000°C, with a regenerative cycle to extend service life and modulate radiation within specific wavelength bands for covert operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If blackbody radiance sources are used to emit thermal radiation in the 3-5 μm or 8-14 μm wavelength bands, then the marker becomes detectable by thermal imaging systems, but the source objects become visible to unauthorized observers and energy conversion efficiency decreases
Solution Approach 1:
The patent applies local quality by making the enclosure selectively transparent to specific wavelength bands. The enclosure material and thickness are designed to transmit thermal radiation in the 3-5 μm or 8-14 μm bands while blocking visible and near-infrared wavelengths, creating different optical properties at different parts of the electromagnetic spectrum.
Solution Approach 2:
The patent employs spectral filtering analogous to color changes, where the enclosure acts as a wavelength-selective filter. It allows certain infrared wavelengths to pass through while blocking visible light, effectively changing the 'optical color' properties of the marker to be invisible to the human eye but detectable by thermal imaging systems.
2Power
If heater temperature is increased to improve blackbody radiation output, then thermal radiance intensity increases, but the service life of the heater decreases due to melting, oxidation, or disintegration
Solution Approach 1:
The patent uses an inert atmosphere (vacuum or inert gas) inside the enclosure to prevent oxidation of the heater element. This creates a protective environment that allows the heater to operate at high temperatures without chemical degradation, significantly extending its service life while maintaining high thermal radiance output.
Solution Approach 2:
The patent employs composite material structures, particularly in the enclosure design that combines materials with specific thermal and optical properties. The enclosure material is selected to withstand high temperatures while providing selective wavelength transmission, and the heater element may use composite structures to resist thermal stress and oxidation.
3Object-affected harmful factors
If a window is added to block visible and NIR energy for covert operation, then covert visibility is improved, but transmittance of thermal radiation in the required wavelength bands decreases
Solution Approach 1:
The window or enclosure is designed with local quality properties where different regions or aspects of the material have different optical characteristics. The material is specifically engineered to be opaque to visible and NIR wavelengths while maintaining high transmittance in the thermal infrared bands, achieving covert visibility without energy loss in the required wavelength ranges.
Solution Approach 2:
The window material exhibits wavelength-selective transmission properties similar to color filtering. It appears opaque or colored in the visible spectrum (providing covert visibility) but is transparent in the thermal infrared regions, allowing thermal radiation to pass through efficiently to thermal imaging detectors.
4Power
If filament temperature is increased beyond oxidization temperature to improve radiation output, then thermal radiation efficiency increases, but the filament degrades rapidly due to oxidation
Solution Approach 1:
The patent places the filament in an inert atmosphere (vacuum or inert gas environment) within the enclosure, preventing oxidation even at temperatures above the normal oxidization point. This allows the filament to operate at high temperatures for improved radiation output efficiency while the inert environment protects it from oxidative degradation, extending its service life.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides efficient thermal radiation output within the 3-5 μm and 8-14 μm bands, maintaining covert visibility and extending the service life of the marker, while being compatible with various imaging devices.
Implementation Method 1
an incandescent filament for producing radiation at least within the thermal portion of the infrared spectrum
Implementation Method 2
the incandescent filament may be surrounded by a pressurized inert gas enclosed within a glass or quartz enclosure
Implementation Method 3
at least a portion of the glass or quartz enclosure may be sufficiently thin so as to enable good transmittance therethrough for thermal radiation approximately in the 3-5 μm wavelength band
Implementation Method 4
emit radiation at least within the thermal portion of the infrared spectrum, and more particularly adapted to emit radiation within the 3-5 μm wavelength band
Data Source
AI summary
In accordance with an aspect of the invention, there is provided a thermal radiation marker (10) adapted to emit radiation within the thermal portion of the infrared spectrum. According to some embodiments of the invention, the thermal radiation marker may include an incandescent filament (16) and a glass or quartz enclosure (12). The incandescent filament may be adapted to produce radiation at least within the thermal portion of the infrared spectrum. The glass or quartz enclosure may include at least a portion that is substantially thin, and may enclose pressurized inert (14) gas and the incandescent filament surrounded by the inert gas. At least a portion of the glass or quartz enclosure may be sufficiently thin so as to enable good transmittance therethrough for tli3rmal radiation approximately in the 3-5&mgr,-m wavelength band. The pressurized inert gas enclosed within the glass or quartz enclosure and surrounding the incandescent filament may enable a regenerative cycle to take place within the enclosure.