Abstract
New moldable, infrared (IR) transmitting glasses and diffusion-based gradient index (GRIN) optical glasses enable simultaneous imaging across multiple wavebands including short-wave infrared, midwave infrared, and long-wave infrared, and offer potential for both weight savings and increased performance in optical sensors. Lens designs show potential for significant reduction in size and weight and improved performance using these materials in homogeneous and GRIN lens elements in multiband sensors. An IR-GRIN lens with Δn = 0.2 is demonstrated.
Highlights
Recent advances in infrared (IR) detector technology combined with the increasing need within military imaging communities to simultaneously image in multiple IR wavebands have exposed the inadequacy of the currently available IR materials to achieve broadband imaging systems with acceptable system performance compatible with platforms constrained by size, weight, power, and cost (SWaP-C), such as airborne and soldier-borne systems.[1]
In an attempt to evaluate the utility of new homogeneous chalcogenide glasses in singlets, bonded doublets, and IR-gradient index (GRIN) lenses in practical imaging systems, design studies were performed using a variety of notional imager forms including a compact single-band LWIR imager, a cryogenically cooled simultaneous dual-band MWIR/LWIR imager, an uncooled, filterseparable MWIR–LWIR imager,[40] and a wideband SWIR–LWIR imager
This lens was much more compact, 27% shorter in overall length, and 40% lighter in weight compared to the baseline lens and had much better performance as the combined modulation transfer functions (MTFs), Fig. 20 (a) Baseline, all-crystalline, 50-mm f ∕1.4 lens designed for a notional uncooled dual-band MWIR/LWIR detector with four elements: ZnSe, GaAs, ZnS, and GaAs. (b) The calculated MTF for this lens at the full 3.5- to 12-μm combined spectrum
Summary
Recent advances in infrared (IR) detector technology combined with the increasing need within military imaging communities to simultaneously image in multiple IR wavebands have exposed the inadequacy of the currently available IR materials to achieve broadband imaging systems with acceptable system performance compatible with platforms constrained by size, weight, power, and cost (SWaP-C), such as airborne and soldier-borne systems.[1]. The modulation transfer functions (MTFs) of lenses in these systems need to be close to the diffraction limit out to about 70- to 100-line pairs/mm Meeting this design criteria requires the lens designer to utilize multiple lens elements with large differences in their refractive indexes and dispersions to limit optical aberrations. Gibson et al.: Diffusion-based gradient index optics for infrared imaging with refraction from the surfaces of the optic, provides the optical designer an additional degree of freedom that may be used in various ways including providing additional optical power or correction of chromatic aberration.[7] GRIN optics for visible wavelengths have been found in nature in the eyes of humans[8] and fish,[9,10] and have been demonstrated in laboratory environments[11,12,13] and commercialized in limited sizes and quantities. Thermal poling has been used to create GRIN profiles with small gradients (Δn 1⁄4 0.05) suitable for microlens arrays.[27]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
