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Novel Single Plane Optics for Lightweight, Compact Imaging Systems

Description:

TECHNOLOGY AREA(S): Electronics, 

OBJECTIVE: Develop and demonstrate an innovative optical element with broadband color correction with applicability in the MWIR (3-5 micrometer) or LWIR (8-12 micrometer) wavebands. The element should be capable of meeting high optical performance using flat surfaces on a thin (<1 mm) substrate with sub-wavelength or super-wavelength sized features formed on the surface. 

DESCRIPTION: As the Army continues to develop focal plane array (FPA) technology, it moves in either the direction of smaller, lighter electronics or larger formats and therefore physical size. In the first instance, these FPAs can be utilized by the Warfighter as situational awareness devices in conjunction with lightweight personal drones. Their performance in this application can be limited by the optics required to form an image onto the FPA. Conventional optics exceed the SWAP payloads these extremely small devices are able to accommodate and the system’s full potential will remain unrealized. In the second case, FPA sizes grow and the optics required for them also grow proportionally. The larger FPAs with greater pixel counts can enhance the situational awareness, survivability, and lethality of the Warfighter. However, the larger optics required and the weight associated can put a strain on the Soldier and decrease their ability to accomplish their mission. Innovative technologies have appeared that allow for novel optical elements that can be on flat substrates of less than a millimeter thickness. The elements, alone or paired with another flat planar optic or a conventional optical element, will allow for very lightweight optics that maintain a high level of optical performance. The technologies that allow for this are features on the scale of the wavelength of light (sub-wavelength or super-wavelength) that can be formed on the surface of the substrate using photolithography or similar techniques as well as increased computing power and sophisticated software to allow for the design and optimization of these features. As the technology development organization for the Army’s FPA and IR camera programs, the U.S. Army CCDC C5ISR Center NVESD provides research, development, and engineering support to programs such as Integrated Visual Augmentation System (IVAS), Soldier Borne Sensors (SBS), and Enhanced Night Vision Goggle (ENVG). In this role, C5ISR Center NVESD is seeking to partner with a small business to develop optical elements that can focus broadband wavelengths with an element that has a thickness of less than 1 mm. Wavebands of particular interest to the Army are the SWIR (1-2 micrometers), MWIR (3-5 micrometers) and, particularly in the short term, LWIR (8-12 micrometers). To support uncooled operation, these lenses will require diffraction-limited or near diffraction-limited performance at low f-numbers (F/0.9 to F/1.2) with high efficiency (>80%) across the waveband. 

PHASE I: Identify the key parameters and requirements associated with military optical systems. Conduct initial studies and design effort related to producing a planar lens on an appropriate substrate for MWIR or LWIR wavebands. Determine necessary equipment and manufacturing process to fabricate planar optical elements. Produce initial proof-of-concept lenses using the design and manufacturing processes to show viable path to meeting Army program requirements. 

PHASE II: Produce planar optical elements on appropriate substrate. Demonstrate diffraction-limited or near diffraction-limited optical performance across a large waveband with high-efficiency at a low f-number. Demonstrate ability to maintain performance across a 30 to 50 degree horizontal field of view. Subject planar optical elements to necessary environmental tests, such as temperature, to show applicability to military systems. Demonstrate path to manufacturing planar optical elements at production quantities. Deliver prototype lenses to C5ISR Center NVESD for further testing and application. 

PHASE III: Design and manufacture planar optics applicable to specific Army programs. Most likely applications for insertion include Soldier Borne Sensor (SBS), a handheld drone for squad level airborne recon and surveillance, Integrated Visual Augmentation System (IVAS), an augmented reality system for individual Soldiers, Enhanced Night Vision Goggles (ENVG), night vision goggles with LWIR camera imagery overlaid, or miniature cameras for covert persistent surveillance. Dual-use applications for planar lenses include any application where thermal cameras are used. Potential applications include law enforcement, fire-fighting, hunting, and paranormal research. 

REFERENCES: 

1: N. Mohammad, M. Meem, B. Shen and R. Menon, "Broadband imaging with one planar diffractive lens," arXiv:1712.09179 [physics.optics]

KEYWORDS: Optics, Planar Optics, Metalenses, IR Lenses, Diffractive Optics 

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