A technique for fabricating novel infrared (IR) lenses can enable a reduction in the size and weight of IR
imaging optics through the use of layered glass structures. These structures can range from having a few thick
glass layers, mimicking cemented doublets and triplets, to having many thin glass layers approximating graded
index (GRIN) lenses. The effectiveness of these structures relies on having materials with diversity in refractive
index (large Δn) and dispersion and similar thermo-viscous behavior (common glass transition temperature, ΔTg
= 10°C). A library of 13 chalcogenide glasses with broad IR transmission (NIR through LWIR bands) was
developed to satisfy these criteria. The lens fabrication methodology, including glass design and synthesis,
sheet fabrication, preform making, lens molding and surface finishing are presented.
An overpass solution for antitank pressure-fused mines was developed and demonstrated for a teleoperated, four-wheeled experimental unmanned ground vehicle hosting a mine detection system using a downlooking ground-penetrating radar. The capability to overpass pressure-activated antitank mines is one way to protect the vehicle. The requirement was to make the vehicle overpass capable by giving it an average footprint pressure of no more than 5 psi using commercially available equipment and without requiring any vehicle modification. An overpass solution was developed and demonstrated using low-pressure, minimal casing rigidity tires that produce a uniformly low ground pressure and enable the vehicle to exert less than the minimum force required to activate the large majority of pressure-fused antitank mines. Overpass requirements are discussed in terms of antitank mine threats, pressure plate size, activation forces, and ground pressure distribution uniformity. A variable-load tire footprint pressure measurement system and laboratory were developed and laboratory evaluation of a number of tire candidates was completed. Laboratory results were demonstrated through field performance demos of the selected low-pressure tire. Results present the successful overpass of various threat representative antitank mines with the pressure plate elevations/exposures at various positions relative to local grade.