Imaging in the short wave infrared (SWIR) wavelength band (0.9um to 2.5um) has generated much attention in recent years with new applications and mission development. Advancements in SWIR sensor and infrared focal plane array (IRFPA) technologies have been the primary drivers to growing interest in areas such as conventional surveillance imaging, as well as advancements in hyperspectral imaging applications.
Why SWIR? The SWIR waveband has some unique qualities to it that make it a useful band for sensing. For imaging applications, SWIR band sensors can uniquely work in the dark as infrared sensors even though the signal is actually reflected off the subject surface, much as visible light does. As a result, SWIR band imaging creates images that are similar to black and white visible cameras in that they have fine detail, including shadows, etc. This aids in scene interpretation. Another phenomenon of SWIR is that there is useful natural background illumination from the night sky. This night radiance, or “nightglow,’ provides an additional reflected signal to aid imaging sensitivity.
This article touches on two key applications for SWIR sensing and detection.