SWIR and NIR low-SWaP zoom lenses: optical design challenges and performances

In this paper we review the optical design challenges and performance of a new NIR+SWIR zoom lens. The main features of this lens include a wide spectral range of 700nm to 1700nm covering both NIR and SWIR bands, a 10x zoom ratio; a 25-250mm EFL range, a F/5.5 to support both 10um and 5um pixel pitch detectors including SXGA format, a low SWaP athermal design, and a high MTF performance along the zoom range and over a wide temperature range. The most significant challenge in this design was the wide spectral range requirement of 700nm to 1700nm, resulting in challenging control of the chromatic aberrations. Another challenge was the reduced SWaP requirements which limited the physical length of the design and therefore increased the performance sensitivity to tolerances. These design considerations and the high-performance results over the full zoom range are described.