Working with Lenses Beyond the Visible

摘要

With the availability of high-resolution indium gallium arsenide (InGaAs) shortwave-infrared (SWIR) sensors, infrared imaging is now practical in commercial and industrial inspection and imaging applications. As the number of SWIR imaging applications has increased, so has the need for affordable off-the-shelf SWIR imaging lenses. While much of the conventional wisdom regarding lens performance criteria in visible imaging translates well to SWIR, SWIR is not without its own unique set of challenges. Infrared wavelengths exist in the part of the electromagnetic spectrum that extends from approximately 700 nm. The IR portion of the spectrum can be divided into sections generally referred to as near (NIR)/shortwave, midwave (MWIR), and longwave (LWIR). While no exact definitions exist, the 700-to-1800-nm SWIR wavelength corresponds approximately to the standard InGaAs sensor response curve (see Fig. 1).