TECHNOLOGY AREAS: Sensors

ACQUISITION PROGRAM: PMA-290 Maritime Surveillance Aircraft

RESTRICTION ON PERFORMANCE BY FOREIGN CITIZENS (i.e., those holding non-U.S. Passports): This topic is "ITAR Restricted." The information and materials provided pursuant to or resulting from this topic are restricted under the International Traffic in Arms Regulations (ITAR), 22 CFR Parts 120 - 130, which control the export of defense-related material and services, including the export of sensitive technical data. Foreign Citizens may perform work under an award resulting from this topic only if they hold the "Permanent Resident Card", or are designated as "Protected Individuals" as defined by 8 U.S.C. 1324b(a)(3). If a proposal for this topic contains participation by a foreign citizen who is not in one of the above two categories, the proposal will be rejected.

OBJECTIVE: Design and build a wavefront sensing system that can measure large amplitude wavefront errors on extended scenes in a tactical environment.

DESCRIPTION: Extended-scene wavefront sensing (WFS) techniques like correlations Shack-Hartmann and Phase-Diversity can be effective for measuring low to moderate atmospheric turbulence levels and optical alignment errors where the wavefront root mean square error (RMSE) is on the order of a wavelength. Astronomical systems and some defense applications fall in this turbulence and optical alignment error regime. However, important and significant applications require WFS techniques capable of measuring optical errors with wavefront RMSE larger than this regime. For example, tactical airborne systems image over paths where turbulence effects can easily defeat conventional WFS technologies. The challenging tactical operational environment, which includes platform vibration and altitude and airflow-induced temperature gradients, also produces large time-varying optical alignment errors. Furthermore, tactical system manufacturing is subject to high-tempo production schedules and cost constraints which do not allow the use of exotic materials or lengthy alignment procedures. These effects result in imagery with a significant reduction in information content compared to a diffraction-limited system with the same size aperture. As a consequence, cost-effective, near-term, innovative methods to perform near real-time measurement of large-amplitude wavefront errors on extended-scenes with the intent to use the technology as input into future tactical adaptive optics systems is sought. These WFS must be capable of measuring optical disturbances covertly (no active beacon) on extended scene imagery. The WFS will have a goal of robustly measuring optical disturbances an order of magnitude greater than those encountered in solar adaptive optics (e.g. for a 1m diameter telescope and an r0 of 10cm a RMSE is calculated of approximately 1wave tip/tilt removed). Its mechanical footprint should not require significant modification or growth in envelope of current tactical system design and aim to fit within a box 10 x 10 x 10 inches. The initial system may not draw more than 1kW of power with a goal of 100W. A design which is scalable to a variety of optical wavebands is preferable. In addition, this system needs to work in a very target rich environment. Modeling of wavefront disturbances caused by atmospheric turbulence and mechanical errors associated with optical reconnaissance and surveillance systems being used at long stand-off and medium altitude should be included.

PHASE I: Develop and prove feasibility of a passive, extended scene wavefront-sensing device. A performance analysis based on optical simulation should be performed.

PHASE II: Build, test and demonstrate a laboratory extended scene large amplitude wavefront sensing prototype with both hardware and software. Perform tower testing under various lighting and atmospheric conditions. Investigate ruggedizing the design and developing a real-time operational implementation of the code.

PHASE III: Integrate into a new system design with a deformable mirror. Integrate the wave front sensors to systems as upgrades as well as new builds.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Broad commercial uses such as ground imaging systems and commercial laser communications would benefit from successful development of this technology.

REFERENCES:
1. Rimmele, Thomas R., (2004). Recent Advances in Solar Adaptive Optics, Proc. SPIE, Vol. 5490 (34) doi: 10.1117/12.551764

2. Rimmele, Thomas R. & Radick, Richard R., (1998). Solar adaptive optics at the National Solar Observatory, Proc. SPIE, Vol. 3353 (72) doi: 10.1117/12.321734

3. Fried, David L., (1998). Branch Point Problem in Adaptive Optics. Journal of the Optical Society of America (JOSA) A, 15 (10), pp. 2759-2768. doi:10.1364/JOSAA.15.002759

4. Barchers, Jeffrey D. (2002). Closed-loop Stable Control of Two Deformable Mirrors for Compensation of Amplitude and Phase Fluctuations. Journal of the Optical Society of America (JOSA) A, 19 (5), pp. 926-945. doi:10.1364/JOSAA.19.000926

5. Tyler, G.A. (2006). Adaptive Optics Compensation for Propagation through Deep Turbulence: Initial Investigation of Gradient Descent Tomography. JOSA A, 23 pp. 1914-1923. doi:10.1364/JOSAA.23.001914

6. Roggemann, Michael C. & Lee, David J. (1998). Two-Deformable-Mirror Concept for Correcting Scintillation Effects in Laser Beam Projection through the Turbulent Atmosphere. Applied Optics, 37, pp. 4577-4585. DOI: 10.1364/AO.37.004577

KEYWORDS: Sensing; Wavefront; Imaging; Adaptive; Optics; Modulation Transfer Function

** TOPIC AUTHOR (TPOC) **

DoD Notice:   Between November 10 and December 12, 2010, you may talk directly with the Topic Authors to ask technical questions about the topics. Their contact information is listed above. For reasons of competitive fairness, direct communication between proposers and topic authors is not allowed starting December 13, 2011, when DoD begins accepting proposals for this solicitation.

However, proposers may still submit written questions about solicitation topics through the DoD's SBIR/STTR Interactive Topic Information System (SITIS), in which the questioner and respondent remain anonymous and all questions and answers are posted electronically for general viewing until the solicitation closes. All proposers are advised to monitor SITIS (11.1 Q&A) during the solicitation period for questions and answers, and other significant information, relevant to the SBIR 11.1 topic under which they are proposing.

If you have general questions about DoD SBIR program, please contact the DoD SBIR Help Desk at (866) 724-7457 or email weblink.