There are many applications for thermal imaging systems where low weight, high performance and high durability are at a premium. These include UAV systems, future warrior programs and thermal weapon sights.
Thermal imaging camera design is restricted by a number external constraints including, detector packaging, detector performance and optical design. This paper describes how, by combining the latest 25µm pitch detector technology, novel optical design and shutter-less image processing a high resolution imager a system weight of 100g can be achieved.
Recently developed detectors have low mass vacuum packages, in this example a 384x288 25um un-cooled microbolometer has a weight of less than 25g. By comparison, earlier 35µm and 50 µm devices were In the region of 40g.
Where cameras are used in harsh environments mechanical shutters present both a reliability issue and additional weight. The low-weight camera utilises Xti Shutter-less technology to generate high quality images without the need for any form of mechanical shutter. The resulting camera has no moving parts.
Lenses for Long Wave Infrared (LWIR) Thermal imaging are typically manufactured using Germanium (Ge) elements. These lenses tend to be designed with f/1.0 apertures and as a result add significant weight to the design. Thanks to the smaller detector pitch and system sensitivity a lens has been designed with a focal length of 14.95mm at f/1.3 where the mass of the optical components is 9g. The final optical assembly, including passive athermalisation has a mass of no more than 15g.