Mobile terawatt femtosecond laser system (MTFLS) for long range spectral sensing and identification of bioaerosols and chemical agents in the atmosphere

Abstract

The present invention relates to a system for detection and identification of airborne biological, chemical and / or nuclear threats such as toxins, spores, bacteria, and viruses in real time at distances from a few meters to several kilometers. Compact femtosecond terawatt laser technology is combined with spectroscopic and mathematical methods for spectral sensing of airborne warfare agents such as bio-aerosols. Trigger sensors and standoff devices based on mobile terawatt femtosecond laser systems are provided that may be placed at strategic monitoring locations. Furthermore, the invention relates to the propagation of airborne ultra-short, ultra-intense laser pulses giving rise to plasma channels (filamentation) producing white light supercontinuum ranging from the ultraviolet (UV), visible (VIS), near infra-red (NIR) and middle infra-red (MIR). According to this invention, the supercontinuum can be directly produced in a particle cloud and hence is uniquely suitable for multi-spectral long-range atmospheric agent and radioactive isotope detection.

Description

[0001] This patent application claims the benefit of U.S. Patent Application Ser. No. 60 / 458,757, filed Mar. 28, 2003 which is hereby fully incorporated by reference.FIELD OF THE INVENTION [0002] The present invention is related to detection and identification of airborne biological and chemical threats in real time at distances from a few meters to several kilometers. Advanced compact femtosecond terawatt laser technology is combined with state-of-the-art spectroscopic and computational methods. These methods are implemented in a unique mobile standoff detection system. BACKGROUND OF THE INVENTION [0003] U.S. Pat. No. 5,175,664 to Diels et al. describes a method and arrangement for discharge of lightning using ultra-short laser pulses. This proposed method enables discharges of electricity transmitted via conductive ionized channels produced by one or more first laser pulses of wavelengths essentially within the ultraviolet (UV) range. The preferred wavelength of operation is about...

AI Technical Summary

Benefits of technology

[0008] This invention presents a promising new trigger sensor and a standoff detection system that can identify airborne biological, chemical, and nuclear agents within a few seconds at distances from a few meters to several kilometers. The biological agent-sensing device is based on the principle of remote differential time resolved monitoring of the atmosphere using ultrashort terawatt laser pulses. According to this invention, concept of advanced compact femtosecond Terawatt (fs-TW) laser technology is combined with state-of-the-art spectroscopic and computational methods. The stand off sensing technology permits real time detection, discrimination, and identification of the full spectrum of threats including; toxins, spores, bacteria and virus. The sensing range spans up to 10,000 meters and can be applied to airborne versions together with stand alone devices at strategically vital locations on sea, air or land. This system would reduce the probability of false alarm and time for detection by more than one order of magnitude. The minimum anticipated range would be of the order of 5-10 spores per liter of air.

[0021] The system may provide for remote monitoring of the atmosphere using ultra-short terawatt laser pulses giving rise to strongly nonlinear optical processes in the air thus generating plasma channel type of filaments encompassing: NIR femtosecond laser pulses at a center wavelength of approximately 800 nm and spectral width of 20 nm creating plasma filaments caused by self-channeling / guiding effects and producing a supercontinuum atmospheric light source ranging for optical sensing applications from the UV to the MIR and UV femtosecond laser pulses operating at a wavelength of approximately 267 nm corresponding to the SHG creating no new wavelengths but propagating with much lower losses up to several km through the plasma channel when compared to the NIR laser pulses.

[0024] One aspect of the invention is that it provides high range resolution over long distances to record the signal of the backscattered light due to Raleigh and Mie scattering from gaseous molecules, bio-aerosols and water droplets in the clouds and plumes. It combines the advantages of the remote sensing techniques and their broadband spectral resolution, with 3D mapping capability. This permits the simultaneous measurement of several bio-aerosol compounds, even with overlapping spectral signatures.

[0025] Furthermore, the invention provides sophisticated differential absorption, fluorescence, Raman Raleigh and Mie scattering, multi-channel, multi-wavelength, multi-spectral LIDAR system for ground based and air based monitoring of bio-aerosols and chemical agents in real time with high accuracy and reduced false alarms for long range detection from about a few meters to 10 km.

Problems solved by technology

However, this patent does not address applications associated with atmospheric spectral sensing of atmospheric gases, pollutants and biological agents using femtosecond terawatt laser generated filaments as light sources.

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