Protecting national borders, military and industrial complexes, national Infrastructure and high-value targets
is critical to national security. Traditional solutions use a combination of ground surveillance radar, motion
detection systems and video surveillance systems. Our development objective was to provide wide area
360-degree surveillance and ground-moving target detection using a passive optical system.
In order to meet this objective, the development of an optical system capable of wide-area surveillance with
intelligent cueing, high-resolution tracking and target identification is required. The predominant approach to
optical surveillance has traditionally been gimbaled narrow field-of-view systems. These systems miss the
majority of events occurring around them because of their inability to focus on anything other than a single
event or object at any one time.
Details of the system requirements definition, design trade studies and selected design configurations are
discussed. The experimental results obtained during the current development phase have provided
consistently high quality images and enhanced situational awareness. A summary of field validation
methods and results is provided.
Many target-tracking applications require an optical system to acquire the target in a wide field of view and then switch to a narrow field of view for tracking, and identification. This process is complicated by the time required, and the resulting loss of image data during the FOV switch. The objective of the investigation was to develop a dual field of view infrared lens system that could accomplish the FOV switch without the loss of any image data. The design was based on achieving this requirement with the lens system integrated with a range of commercially available mid wave infrared cameras. The results of trade studies and evaluation of user mission profiles, resulted in a system with 100mm and 500mm focal lengths, with a field of view switch within one frame period. The FOV switch was further required to coordinate with the frame synchronization timing to eliminate any loss of data during the FOV change. The requirements also specified a fully integrated system housed in a sealed enclosure that would support extended field deployment in a military environment with no maintenance. Presented herein are details of the design trade studies and specification development, highlights of the resulting optical design with a discussion of the optimization methods employed. Also included are details of the packaging challenges and solutions and sample performance data collected from successful field tests of the first two prototype units.
To explore the feasibility of utilizing an IR imaging system to support flow visualization studies, an initial series of tests were conducted using an AN/AAS-38, NITE Hawk targeting pod. The targeting pod, installed on the left side of an F/A-18 aircraft provides a stabilized infrared imaging capability in the 8-12 micron spectral band. Initial data acquired with system indicated that IR thermography was a very promising tool for flow visualization. For the next phase of the investigation, an advanced version of the NITE Hawk targeting pod equipped with a staring 3-5 micron sensor was utilized. Experimental results obtained with this sensor indicated improved sensitivity and resolution. This method was limited to position the experiment and chase aircraft sufficiently close to each other and with the sightline angle required to acquire the region of interest. For the current phase of the investigation, the proven 3-5 micron staring sensor was deployed in an externally mounted podlet, located on the experimental aircraft with a fixed line of sight, centered on the region of interest. Based on initial data collection efforts, this approach appears to provide consistent high quality data for a wide range of flight conditions. To minimize the size of the podlet and resultant drag, the sensor was oriented parallel to the air flow. This also placed the line of sight parallel to the experiment. A fold mirror was incorporated in the design to fold the line of sight inboard and down to center on the region of interest.
The experimental results obtained during the current test phase have provided consistently high quality images clearly mapping regions of laminar and turbulent flow. Several examples of these images and further details of the experimental approach are presented.
The Navy and Marine Corps F/A-18 pilots state that the targeting FLIR system does not provide enough target definition and clarity. As a result, high altitude tactics missions are the most difficult due to the limited amount of time available to identify the target. If the targeting FLIR system had a better stand-off range and an improved target contrast then the pilots' task would be easier. Unfortunately, the replacement cost of the existing FLIR equipment is prohibitive. The purpose of this study is to modify the existing F/A-18 targeting FLIR system with a dual-band color sensor to improve target contrast and stand- off ranges. Methods: A non-real-time color sensor fusion system was flown on a NASA F/A-18 in a NITE Hawk targeting FLIR pod. Flight videotape was recorded from a third generation image intensified CCD and a first generation long-wave infrared sensor. A standard visual search task was used to assess whether pilots' situational awareness was improved by combining the two sensor videotape sequences into a single fused color or grayscale representation. Results: Fleet aviators showed that color fusion improved target detection, but hindered situational awareness. Aviators reported the lack of color constancy caused the scene to be unaesthetically pleasing; however, target detection was enhanced. Conclusion: A color fusion scene may benefit targeting applications but hinder situational awareness.