The Department of Defense, specifically the Navy, is seeking innovative solutions to address the persistent issue of biofouling on submerged broadband optical surfaces through the Small Business Innovation Research (SBIR) program. The objective is to develop a cost-effective and environmentally friendly nanotechnology that mitigates biofouling and salt mineral deposition on optical head windows, ensuring high optical transmission and durability. This technology is crucial for enhancing the performance of optics and sensors in marine environments, with potential applications extending to various sectors, including defense and commercial industries. Proposals are due by February 5, 2025, with the opportunity opening on January 8, 2025, and further details can be found at the official solicitation link: https://www.dodsbirsttr.mil/topics-app/.

## Description

Biofouling has been a long-lasting problem in a variety of marine systems. Optics and sensors suffer reduced performance and, in some cases, catastrophic failure due to biofouling. No suitable optical surface coating is available to mitigate biofouling and salt mineral depositions. Legacy coating (Ameral) was effective on imaging systems, but Ameral has been discontinued due to environmental and health hazards. A replacement solution (Rain-X) has a short lifetime and requires frequent beam director window cleaning applications. Neither solution is effective for Photonics periscope and Laser applications, since both solutions absorb light and need periodic applications. No current market options combine the required hydrophobicity and broadband anti-reflection (AR) properties when applied to broadband optical surfaces exposed to a marine environment. Nanostructured materials with super-hydrophobic self-cleaning surfaces, and hyper-branched polymer structures with hydrophilic-ended or activated foulant releasing groups are incorporated in most current coating techniques on the glass or sensors surface. However, advanced nano-structured coatings are usually associated with reduced mechanical properties, sophisticated fabrication processes, and extensive use of chemicals resulting in higher costs and more environmental issues. The Navy seeks an innovative nanotechnology to mitigate broadband AR coating challenges. In this STTR topic, the Navy is looking for a cost effective and environmentally friendly innovative approach to mitigating biofouling on submerged glass and sensors. The exposed broadband optical surfaces employed are either sapphire, aluminum oxide, spinal, gallium germinate, or Germanium Oxide (GeO) . The proposed innovative technology should address biofouling and salt mineral deposition mitigation. Both an active and passive solution will be considered. Solutions must provide self-cleaning of the optical and sensor surface with ultra hydrophobicity and broadband AR coating. Proposals will be evaluated on: <ol><li> Nano structured deposition optical surface transmission wavelength from 0.45 to higher than 5 micrometer with greater than 90% transmission and higher than 99% optical transmission between 1 to 1.5 micrometer Wavelength. </li></ol><ol><li> Nano structure coating on head window will have wave-front error less than wavelength of light/50. </li></ol><ol><li> Optical Surface size of minimum 12-inch diameter shall not introduce any polarization or birefringence. </li></ol><ol><li> Surface durability more than 720 hours of continuous operation against any salt/mineral and any marine particle. </li></ol><ol><li> Optical surface should introduce self-cleaning technology.</li></ol>

## Objective

Design an innovative approach to reduce or mitigate biofouling on submerged broad band optical head windows.

## Phase I

Develop a concept to solve the Navy&rsquo;s biofouling problem on Optical Head Window. Demonstrate the feasibility of the innovative concept to solve or mitigate the Navy&rsquo;s problem of broad band glass with nano structure for anti-reflection (AR), biofouling and salt mineral deposition mitigation. Deliverable will include the initial modeling of the biofouling mitigation on broadband developed glass optical surface with salt mineral deposition and broad band AR coating. The Phase I Option, if exercised, will include the validation modeling and capabilities description to build a sample prototype optical glass for testing to mitigate biofouling of the proposed broadband glass surface at Phase II.

## Phase II

Develop the biofouling mitigated broadband glass with self-cleaning optical surface for an HEL beam director or Photonics periscope for data collection analysis. Deliver the prototype to the Navy for further evaluation. In Phase II Base the awardee shall demonstrate the broad band glass GeO and its biofouling properties and hydrophobicity. Test of the glass shall be performed inhouse.The biofouling and salt mineral deposition mitigated broad band HEL window shall support multi kW laser power transmission with self-cleaning surface technology. The wave front error of the biofouling mitigated surface shall not be bigger than optical wavelength/50 of the optical surface. The Bio fouling mitigated surface shall also have higher than 160-degree contact angle with ultra-hydrophobic surface for water shedding and have broadband (visible to Mid wave IR) anti reflection properties.

## Phase III: Dual Use Applications

Complete the final design of the biofouling mitigated broad band glass with self-cleaning optical surface. Support the Navy in transitioning the technology to Navy use. This technology can have application to both DoD and commercial sectors such as ship&rsquo;s hulls, underwater pipes, oceanographic sensors, terrestrial optical sensors and laser systems, drilling equipment, oil platforms, fishing industry, power plants, and aquaculture systems.

Marine Biofouling Mitigation and Innovative Broad Band Hydrophobic Glass Development

STTR Opportunity Analysis

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Opportunity Snapshot

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