SBIR-STTR Award

Achieving NASA's strategic goal of 'Expanding Human Knowledge through New Scientific Discoveries' requires high-performance instrumentation capable of operating under extreme conditions while maintaining a low size, weight, and power. Hyperspectral imaging (HSI) systems represent a class of instruments that have played a significant role in previous NASA missions in remote sensing and planetary surveying on Earth and other planetary systems. The HSI systems on these missions have relied on bulky optics that also require large system sizes to achieve high spectral resolution. The large size and mass of these spectrometers represent a significant barrier to widespread adoption due to the opportunity cost of the space, weight, and power consumption. Tunoptix proposes to utilize meta-optics in conjunction with computational imaging to drastically reduce the SWaP of HSI systems while maintaining high spectral and spatial resolution. A meta-optic consists of an array of subwavelength scatterers, which locally control the amplitude, phase, and spectrum of incident light with high spatial resolution. A metasurface is optically thin, with an active layer thickness of of less than a micrometer, and total optical thickness on the order of millimeters. Tunoptix will develop a HSI system based on an optical front-end and computational back-end. This approach leverages the unique ability of meta-optics to implement near-arbitrary optical functionalities to implement a well-conditioned wavelength-dependent transformation on incident light. This will then be decoded using a low latency postprocessing algorithm to extract a high-fidelity hyperspectral image. With this method, Tunoptix well demonstrate a compact, snapshot polarization independent HSI system with F/1.8, a 10 cm x 8 cm x 4 cm form factor, and a mass of less than 1 kg operating over a bandwidth of 350-1050 nm, and with over 40 channels. Potential NASA Applications (Limit 1500 characters, approximately 150 words): A drastically lower SWaP snapshot HSI system would reduce the opportunity cost for their adoption in a wider set of NASA missions and applications. In particular, applications of a low SWaP, snapshot HSI system would include satellite-based and rover-based imaging and spectroscopy of planetary surfaces, airborne remote sensing of coastal and oceanic regions, and in-field inspection of mission-critical satellite systems. Potential Non-NASA Applications (Limit 1500 characters, approximately 150 words): The primary applications for an HSI system in the private sector would be in quality control and inspection for industrial settings, and plane-based or drone-based surveying. In these applications, the design would increase throughput of the customer's processes while maintaining spectral and spatial resolution and relaxing stabilization tolerances when compared to pushbroom HSI systems. Duration: 6

Large aperture optics are important for various applications including remote sensing and gigapixel imaging, but such optics are generally very heavy. For example, the optics in the Hubble telescope (aperture of ~ 2m) are on the order of 1000 kg. The emerging field of meta-optics, which utilizes arrays of sub-wavelength nano-scatterers to manipulate wave-fronts can drastically reduce the size and weight of optical systems. Each scatterer is individually engineered and arranged in a precisely aligned grid to enable optical functionalities that are difficult, if not impossible to achieve using conventional refractive optics. Moreover, these flat optical elements can be ultrathin, with active layer thicknesses on the order of a single optical wavelength. However, the imaging performance and achievable apertures of the most sophisticated meta-optics are currently constrained by fundamental limitations of electromagnetic responses, Seidel aberrations, available electromagnetic design software, and practical manufacturing challenges. Tunoptix proposes to address these limitations by using a photolithography compatible metasurface-based computational imaging system where the metasurface is supported by an image processing backend to produce high fidelity, aberration-free images. Tunoptix’s effort is comprised of three complementary thrusts focused on: (1) the design and optimization of centimeter and decimeter-scale meta-optics with accompanying reconstruction software, (2) the development of a scalable photolithography fabrication process for centimeter and decimeter-scale metasurfaces, and (3) the characterization of the fabricated metalenses and data acquisition for use in learned reconstruction models. In thrust (1), Tunoptix will use metasurface scatterer geometries described by simple shapes such as square pillars with modest aspect ratios to make our designs easily compatible with conventional deep UV photolithography techniques. Instead of using difficult-to-fabricate intricate scatterer geometries to correct optical aberrations, Tunoptix will instead leverage computational imaging techniques to perform image reconstruction. In thrust (2), Tunoptix will fabricate the centimeter-scale designs by using a foundry service. The metasurface designs will be amended such that they fall within the design rules of the chosen foundry service. In addition, to fabricate decimeter-scale designs, a step-and-stitch process will be developed to minimize the required reticles. In thrust (3), the fabricated metalenses will be fully measured in terms of their chromatic and Seidel aberrations by measuring their point spread functions and characterized in terms of their dependence on incident wavelength, angle of incidence, and object depth. These point spread functions will then be used to reconstruct high quality images in lab and real-world settings. A learned reconstruction algorithm will then be fine-tuned using the point spread function and imaging data.