Streak Tube Imaging LIDAR (STIL) for 3-D Imaging of Terrestrial Targets

摘要

The Streak Tube Imaging LIDAR (STIL) is a patented active imaging system using a pulsed laser and a streak tube receiver to produce high resolution 3-D range and intensify imagery. The laser beam is diverged in the cross-track (azimuth) direction into a fan beam which is projected into the scene as a cross-track line. The backscattered light from the scene is imaged onto the streak tube's photocathode, and is time (range) resolved by electrostatically sweeping the resultant electron beam across the streak tube's phosphor screen to generate from each laser pulse a continuous intensity-range- azimuth image which is captured by a CCD array fiber optically coupled to the phosphor screen. A high resolution 3-D image of the scene is produced from multiple sequential frames formed by repetitively pulsing the laser in synchrony with the CCD frame rate as an airborne platform 'push broom' scans or as a single-axis scanner on a ground-based platform scans the laser fan beam over the scene. The frames are registered using data from an inertial measurement with (IMU) to compensate for platform motion. The system can also use GPS data with the 3-D data from the sensor for absolute geolocation of points in the scene. Ground based field tests were conducted with STIL operating at 128 range by 512 azimuth pixels over 12.6 degrees and 47.6 degrees azimuthal fields-of-view (FOV). Targets included a HMMWV, a C-130 transport plane, two range resolution panels, and a contrast resolution panel. Data was collected at ranges from 100 m to 1 km. Data from these tests demonstrating achievement of pixel limited image resolution and 6 inch range resolution are presented.