11 May 2017 Design of multiband optics using updated athermal/achromatic glass map
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Recently, optical materials have been developed by Schott and NRL to improve material selection in the SWIR, MWIR, and LWIR wavelength regions. In addition, new multiband detectors are reaching maturity, leading to a natural push for common aperture lens systems. Detectors that can span the SWIR/MWIR, MWIR/LWIR or SWIR/MWIR/LWIR wavelengths regions will require complex optical systems to effectively utilize their full potential. Designing common aperture wide-band systems that are both achromatized and passively athermal, especially while maintaining SWAP-c (size, weight, power and cost), poses significant challenges. Through use of the updated γν-ν diagram, which provides guidance on material combinations that both achromatize and athermalize, part of that challenge is reduced. This updated γν-ν diagram uses instantaneous Abbe number and peak wavelength. The instantaneous Abbe number is a function of wavelength and is the scaled reciprocal of the instantaneous dispersion. The instantaneous Abbe number is defined at the peak wavelength, which occurs when the second derivative of the index of refraction goes to zero. Three examples will be presented using this updated athermal/achromatic glass map to demonstrate its effectiveness. These design examples will include a SWIR/MWIR design, a MWIR/LWIR design and, a SWIR/MWIR/LWIR design.
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J. L. Ramsey, J. L. Ramsey, B. L. Unger, B. L. Unger, "Design of multiband optics using updated athermal/achromatic glass map", Proc. SPIE 10181, Advanced Optics for Defense Applications: UV through LWIR II, 1018103 (11 May 2017); doi: 10.1117/12.2260898; https://doi.org/10.1117/12.2260898


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