Monocular Passive Ranging by an Optical System With Band Pass Filtering

<p>An instrument for monocular passive ranging based on atmospheric oxygen absorption near 762 nm has been designed built and deployed to track emissive targets including the plumes from jet engines or rockets. An intensified CCD array is coupled to variable band pass liquid crystal display filter and 3.5 - 8.8 degree field of view optics to observe the target. By recording sequential images at 7 Hz in three 6 nm width bands the transmittance of the R-branch of the O2 (X-b) (00) band is determined. A metric curve for determining range from transmittance is developed using the HITRAN spectral database. A low cost system was designed and ground tested at ranges of 50 -380 m using halogen and incandescent light sources establishing an average range error of 12%. The system was first deployed for a ground test viewing an F-16 in afterburner at ranges of 0.35 - 4.8 km establishing a range error of 15% despite the presence of optical turbulence and a structured source spectrum. Finally the instrument was flight tested in a C-12 imaging an F-16 in afterburner at ranges up to 11 km. The target was manually tracked and pointing jitter limited image interpretation. A study of range error as a function of signal-to-noise ratio produced superior results to previous methods using Fourier Transform Spectroscopy. However increased signal relative to background scatter will be required for accurate ranging for these tactical air-to-air scenarios. The promise for improved instrument performance is discussed.</p><p>This work has been selected by scholars as being culturally important and is part of the knowledge base of civilization as we know it. This work was reproduced from the original artifact and remains as true to the original work as possible. Therefore you will see the original copyright references library stamps (as most of these works have been housed in our most important libraries around the world) and other notations in the work.</p><p>This work is in the public domain in the United States of America and possibly other nations. Within the United States you may freely copy and distribute this work as no entity (individual or corporate) has a copyright on the body of the work.</p><p>As a reproduction of a historical artifact this work may contain missing or blurred pages poor pictures errant marks etc. Scholars believe and we concur that this work is important enough to be preserved reproduced and made generally available to the public. We appreciate your support of the preservation process and thank you for being an important part of keeping this knowledge alive and relevant.</p>