Athermalization and Achromatization of Multiband Optics using Instantaneous Abbe Number

摘要

Over the past few years, new detector technologies have enabled multiband detection through a single aperture. This creates significant SWAP advantages (size, weight and power) and has spurred significant interest in multiband optics (for instance SWIR/MWIR, MWIR/LWIR, etc.). However, due to the small number of materials available in the infrared regions, passive optical athermalization and achromatization can be challenging even over single waveband. This becomes even more challenging in the case of multiband optics. One method for determining appropriate material combinations for athermalization and achromatization is use of a γ * v vs. v diagram. We examine an updated form of the γ * vvs. v diagram using instantaneous Abbe number. While Abbe number is an effective metric for dispersion within single bands, it becomes less reliable when extended to wider wavelength ranges. Instantaneous Abbe number allows for a wider waveband to be defined, without a loss of generality; and this allows for an updated definition of the γ * v vs. v diagram for the development of multiband optics. We present an example of a multiband lens as well as compare the typical definition of Abbe number with instantaneous Abbe number to determine the validity of the updated model.