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Optical Additive Manufacturing in Mid-Wave and Long-Wave Infrared Bands


OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Advanced Computing and Software; Advanced Materials OBJECTIVE: Demonstrate the capabilities and benefits of applying state-of-the-art additive manufacturing (AM) for Mid-Wave (MWIR) and Long-Wave infrared (LWIR) refractive lenses, and optically transparent windows, by developing novel AM methods and processes using toxic precursor materials. DESCRIPTION: For the last few decades, the military has used LWIR (8–12 µm wavelength range) and MWIR (3–5 µm wavelength range) sensors and cameras for reconnaissance and surveillance of targets of interest by thermal emissions. These MWIR and LWIR sensors and cameras use hazardous materials, mercury (Me), cadmium (Cd), and tellurium (Te) as precursor materials in their optics manufacturing. Indium phosphide (InP) and zinc sulfide (ZnS) have emerged as a presumably less hazardous alternative to cadmium-based optics, yet little is known about their toxicological effects. Currently, no commercial AM system can be used to repair MWIR and LWIR imaging quality optical glass with sufficient dimensional accuracy and surface finish. A robust MWIR and LWIR AM process to perform net deposition of MWIR and LWIR optical materials on existing glass substrate, which can provide MWIR and LWIR optical imaging surface quality, is needed. This MWIR and LWIR AM process should be able to deposit hazardous MWIR and LWIR optical materials within the desired transmission band, and provide a smooth optical surface quality, so that minimum post-processing is needed. With homogeneous glasses, AM has the potential to rapidly repair existing MWIR and LWIR optical systems with no or minimal post processing (e.g., least amount of time for a final polish to achieve a desired surface flatness, such as lambda/10.) This will dramatically enhance the logistics and maintenance of the Navy’s optical systems. In January 2007, President George W. Bush signed Executive Order (EO) 13423 (2007) Strengthening Federal Environmental, Energy, and Transportation Management, requiring government agencies to reduce the quantity of toxic and hazardous chemicals and materials that are acquired, used, or disposed. Cadmium is among the chemicals to be reduced by the DoD. As a result of this regulation, the use of cadmium significantly raises the maintenance costs throughout the life of MWIR and LWIR sensors and cameras. Due to these increasing costs, regulatory pressure, and risk to personnel performing, a robust MWIR and LWIR AM process to repair MWIR and LWIR optical sensors and cameras with good optical properties and surface quality is needed. This MWIR and LWIR AM process should be able to deposit MWIR and LWIR optical precursor materials within the desired transmission band and provide a smooth optical surface quality so that minimum post-processing is needed. The Navy desires to understand how to implement and use a novel MWIR and LWIR AM process with respect to: (a) optical materials deposition within the desired transmission band, thus providing optics with an optical surface quality of lambda/10 flatness with minimum post-processing; and (b) how and when MWIR and LWIR AM will be financially beneficial to support field optical repairs. Emphasis should be placed on MWIR and LWIR AM systems with respect to minimizing hazards, risks, accidents, and near misses, cost reduction (both production and Non-Recurring Engineering (NRE) for tooling), sustainability (waste reduction, reduced need for large dedicated tools, etc.), and AM manufacturing process improvements. The proposer should consider this effort as the innovative advancement of developing a novel MWIR and LWIR AM systems for MWIR and LWIR optical components repairs that meets the following performance objectives: 1. Prove by demonstration the state-of-the-art novel MWIR and LWIR AM methods to produce an optical surface with a flatness having the following characteristics: (a) a net surface flatness of lambda/10, Centration = 3 arc minutes, Clear Aperture > 90% of Diameter; (b) with a transmission window from 3—5 µm and a second transmission window 8—12 µm; (c) Clear aperture must be 3 in. in diameter; and (d) a thermalized design that must work from -54° to 90°C. 2. Provide a cost analysis of MWIR and LWIR AM for MWIR and LWIR optical components versus machining or tooling, which should include the cost of time to acquire the parts (impact on enabling a rapid prototype turnaround), as well as material and any associated labor costs. 3. Based on research, develop a timeline of events for when the developed MWIR and LWIR AM technology may be extended to high-rate production of optical components. 4. Develop a plan and process for using the developed AM technology for the manufacturing of MWIR and LWIR optical components, and ultimately implemented to develop and manufacture selected MWIR and LWIR optical components. PHASE I: Analyze the current state-of-the-art MWIR and LWIR AM technology. Identify the technological, innovative, and reliability challenges to determine the feasibility of using MWIR and LWIR AM for the refurbishment of MWIR and LWIR optical components (the required optical properties, full densification, and smooth surface finish, as provided in the Description), and propose a plan for how these will be addressed. Perform a preliminary identification of hazards and cost comparisons for MWIR and LWIR AM of MWIR and LWIR optical components. Demonstrate the feasibility of the concept in meeting topic description, and establish that the concept can be minimally toxic, feasible, and affordably produced. Feasibility will be established by some combination of initial prototype testing, analysis, or modeling. Affordability will be established by analysis of the proposed materials and processes, and by comparison to existing and established semiconductor, additive, and automated manufacturing techniques. The Phase I Option, if exercised, will include the initial design specifications and capabilities description to build a prototype using MWIR and LWIR AM. The Phase I effort will include prototype plans to be developed under Phase II. PHASE II: Design and fabricate, using MWIR AM, a MWIR window with an 8° or 0° face angle for imaging in the MWIR (3-5 µm) with a surface flatness of lambda/10. Perform optical testing on the components and compare to current production components. Integrate the prototype components into a U.S. Government-provided unmanned air vehicle (UAV) turret assembly, and perform a series of evaluation tests to validate feasibility. Government provided UAV specification documentation that includes metrics and testing methods will be provided prior to Phase II. Develop an initial process that will be further refined in Phase III as part of Government depots using the MWIR and LWIR optical component MWIR and LWIR AM capability, including a timeline of events envisioned. Determine optimized processing conditions, cost model, and report commercial viability of MWIR and LWIR AM process. PHASE III DUAL USE APPLICATIONS: Provide representative prototype samples using the developed AM process to a U.S. Government laboratory and a Government depot. Evaluate, by conventional metrology, the innovative optical surface with the flatness, as stated in the Description, to ensure the AM process is on par with an optical flatness produced by common practice. Transition the AM process to a U.S. Government laboratory and a Government depot. Perform testing and make improvements to the AM process based upon the Government’s evaluations and results. Begin producing optical MWIR and LWIR AM components for field testing and use in military systems. Laser manufacturers, camera manufacturers, and imaging technology manufacturers will benefit from this AM technology because they can now specify custom-size optical components with unique MWIR and LWIR transmission profiles that are not currently available with conventional optical processing. REFERENCES: 1. McCarthy, P. W. (2015). Gradient-index materials, design, and metrology for broadband imaging systems. University of Rochester. 2. Willis, K., Brockmeyer, E., Hudson, S., & Poupyrev, I. (2012, October). Printed optics: 3D printing of embedded optical elements for interactive devices. In Proceedings of the 25th annual ACM symposium on User interface software and technology (pp. 589-598). 3. Brockmeyer, E., Poupyrev, I., & Hudson, S. (2013, October). PAPILLON: designing curved display surfaces with printed optics. In Proceedings of the 26th annual ACM symposium on User interface software and technology (pp. 457-462). 4. Urness, A. C., Anderson, K., Ye, C., Wilson, W. L., & McLeod, R. R. (2015). Arbitrary GRIN component fabrication in optically driven diffusive photopolymers. Optics express, 23(1), 264-273. 5. Gissibl, T., Thiele, S., Herkommer, A., & Giessen, H. (2016). Two-photon direct laser writing of ultracompact multi-lens objectives. Nature Photonics, 10(8), 554-560. 6. Luo, J., Gilbert, L., Qu, C., Wilson, J., Bristow, D., Landers, R., & Kinzel, E. (2015, June 8–12). Wire-fed additive manufacturing of transparent glass parts. In International Manufacturing Science and Engineering Conference (Vol. 56826, p. V001T02A108). American Society of Mechanical Engineers. 7. Teichman, J., Holzer, J., Balko, B., Fisher, B., & Buckley, L. (2013). Gradient index optics at DARPA. Institute For Defense Analyses Alexandria Va. 8. Castillo-Orozco, E., Kumar, R., & Kar, A. (2019). Laser-induced subwavelength structures by microdroplet superlens. Optics express, 27(6), 8130-8142. 9. Gibson, D., Bayya, S., Nguyen, V., Sanghera, J., Beadie, G., Kotov, M., McClain, C., & Vizgaitis, J. (2019, May). Multispectral IR optics and GRIN. In Advanced Optics for Imaging Applications: UV through LWIR IV (Vol. 10998, p. 109980D). International Society for Optics and Photonics. 10. Executive Order 13423—Strengthening Federal Environmental, Energy, and Transportation Management, 3 C.F.R. 3919 (2007). KEYWORDS: additive manufacturing (AM); lens; window; toxic; repair; optical
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