This paper reviews work done at Trex Enterprises Corporation over the past 18 years on electro-optic surveillance and tracking systems. The range of objects that can be detected and tracked cover awide range of brightness and velocities, from slower moving mortars to fast moving bullets.
A megawatt-class high energy laser aboard a Navy ship could provide effective self defense against modern anti-ship missiles. The free electron laser is a candidate for use in this mission, and has several advantages over chemical lasers, which have been previously considered. One obvious advantage is wavelength tune-ability of teh FEL-allowing tuning of the laser wavelength to an atmospheric spectral window of minimum absorption. This study reports on analysis performed to select optimum wavelengths for a ship-based FEL in consideration of atmospheric effects. We examine atmospheric absorption, scattering, trubulence, and thermal blooming, and compare their relative importance in optimizing power in the bucket on target for representative scenarios. We also examine the issue of thermal blooming caused by atmospheric aerosol absorption, and examine the relative absorption of open-ocean vs continental aerosols. We find excellent propagation results at 1.625 and 1.047 microns.
We describe test results using the FIRST (Fast InfraRed Sniper Tracker) to detect, track, and range to bullets in flight for determining the location of the bullet launch point. The technology developed for the FIRST system can be used to provide detection and accurate 3D track data for other small threat objects including rockets, mortars, and artillery in addition to bullets. We discuss the radiometry and detection range for these objects, and discuss the trade-offs involved in design of the very fast optical system for acquisition, tracking, and ranging of these targets.
This paper describes a prototype sensor system for detection and 3D tracking of bullets and other small projectiles. The intended purpose of the system is to rapidly locate a sniper to a few meters accuracy at ranges to 1 km in three dimensions. The system detects and tracks a single bullet, and based on the measured 3D trajectory, backtracks to the sniper location. Details of the system are describe including optics, infrared camera, scanning system, laser ranging system, computer control and electronics, and data reduction algorithm. The system has been field tested against bullets, and has been shown to locate a sniper to a few meters accuracy at 500 meters range. Plans for improving tracking performance are also described.
We are currently building a custom adaptive optics system for viewing missile defense testing in Hawaii. The system will utilize natural target emission in the 3 - 5 micron MWIR for imagery, as well as for sensing the phase distortion caused by atmospheric turbulence. Use of the system with the 3.67 meter AEOS telescope will provide near-diffraction-limited performance for imaging at very long range and low elevation angle.
The ROBS instrument has recently acquired unique imagery of a missile intercepting an airborne drone target. We present a summary of that mission. We also present imagery of three airborne targets collected while the ROBS instrument simultaneously tracked all three aircraft. The recent test data highlights the capability of the ROBS instrument for autonomous acquisition, tracking, and imaging of multiple targets under field test conditions. We also describe improvements to the optical system currently underway.
We present a summary of recent imagery and tracking measurements made with the ROBS laser radar system operating at White Sands Missile Range. The ROBS instrument utilizes a 0.5 meter aperture optical system, 3 - 5 micron imaging cameras, and a coherent CO2 laser radar for range and Doppler measurements. The optical system is based on a roving fovea design, which enables signal target tracking over large angles at high track update rate, and rapid retargeting between multiple targets. Results of several field measurements are presented.
Range information from a laser radar can be used to rapidly converge target track files for theater missile defense from an airborne sensor platform. This paper examines the application of laser radar technology to this mission. Eyesafe lasers including carbon dioxide, holmium/thulium, and YAG shifted by optical parametric oscillators or Raman cells are considered. Performance analyses include the effects of wavelength dependent target cross sections, atmospheric attenuation and background radiation, and either direct or heterodyne detection processes on the received signal to noise ratio. Signal processing analyses include the effects of noise statistics, target fading for either direct or heterodyne detection, and the optical wavelength dependent effects of atmospheric turbulence on system false alarm and detection probabilities.
Basing laser radar systems aboard aircraft provides capability for accurate tracking of ground, airborne, and ballistic missile targets from long range. The atmospheric effects of long propagation paths impact the performance of laser radar systems in two important ways -- molecular and aerosol extinction and optical turbulence. This paper provides quantitative assessment of the impact of these effects for laser radar wavelengths beyond 1.4 microns. The treatment of round-trip turbulence on direct detection systems is believed to be the first estimate of this effect. A more complete system analysis is underway and will be described in a forthcoming paper.
Basing laser devices on aircraft leads to new problems in atmospheric transmission due to the long, nearly-horizontal propagation paths in the upper troposphere and stratosphere. This paper analyzed the molecular and aerosol extinction impact on near-IR aircraft-based laser performance. Calculations using standards atmospheric models are reviewed. Recent volcanic activity has required examination of the impact of stratospheric aerosols for propagation paths of interest. Calculations as a function of geometry are presented which use satellite limb viewing data to asses the impact of cirrus clouds and volcanic aerosols.
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