TECHNOLOGY AREAS: Air Platform, Electronics

ACQUISITION PROGRAM: PMA 261 - CH-53K Heavy Lift Helicopter, ACAT I; PMA-275; PMA-209

The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), which controls the export and import of defense-related material and services. Offerors must disclose any proposed use of foreign nationals, their country of origin, and what tasks each would accomplish in the statement of work in accordance with section 3.5.b.(7) of the solicitation.

OBJECTIVE: To advance the state-of-the-art of non-mechanical LADAR for the purpose of developing a near-real-time, light-weight, terrain mapping and obstacle detection capability for helicopters landing in reduced visual cue environments (ie: brown-out, white-out, etc). This SBIR topic is target towards development of an electronically scanned fiber laser array or suitable alternate technology that provides a very high speed laser beam steering capability. Concurrent with this development will be the receiver technology the will accompany the scanned array since they will use the same optics.

DESCRIPTION: Laser based sensors for measuring ground speed (Vg) and height above the ground (AGL) are very attractive for providing to the helicopter pilot, information regarding the aircraft position and drift over the ground in reduced visual cue environments. A laser-based system is currently under development which uses a 1.55 micron pulsed fiber laser, and is class I eye-safe. The system will be light weight and robust with no moving parts and is considered the first step towards a robust landing solution for helicopters. Significant progress has been made in the area of laser phased array technology for non-mechanical laser beam steering. One such technology is a two-dimensional optical beam deflector operated by wavelength tuning. For one dimensional beam steering, the laser beam to be deflected is split into N co-directional sub-beams of equal intensity with the aid of a plane-parallel plate. These sub-beams experience a relative time delay, which translates into a phase difference, thus forming a phased array. This concept has been carried further by to a 2-dimensional array and demonstrated in a lab. Other work has been conducted under the DARPA Steered Agile Beam (STAB) program. To achieve the goal of a light-weight steer-able beam system, they have pursued several candidate component technologies such as micro-electro-mechanical systems (MEMS) structures. In one of the MEMS projects, they are developing an array of actuators that translates a micro-lens array in both orthogonal lateral directions. Another technology under investigation is an electro-statically driven actuator approach which consists of micro-mirrors with novel "twin-crank" actuators that efficiently convert lateral motion into rotational motion in two dimensions. Another technique for steering a beam has been to use a liquid crystal optical phased array which can be fabricated such that the phase change introduced along the array can be electrically controlled. In this fashion, an incident beam sees a varying refractive index as it propagates along the array and is thereby steered. A significant amount of work has been accomplished by AFRL in the area of phased array laser technology, as well, in particular, a system called PAPA which is a phased array of phased arrays.

Although, there has been significant advancement in fiber lasers and non-mechanical agile beam steering, there is much work yet to be done to make this into a practical system that can survive the harsh helicopter environment. The state-of-the-art of electronic fiber laser beam steering needs to be advanced in order to achieve a practical LADAR system suitable for near-real-time terrain mapping. Additionally, the state of fiber laser receiver technology needs significant advancement in order to function with the above mentioned scanning laser. Although a separate aperture for the laser return can be used, in the interest of a simplified compact and light design, it is highly desirable to use the same aperture for coherent transmit and receive functions, To accomplish this, sub-aperture receive techniques need to be developed.

PHASE I: Determine the feasibility of developing a fully functional, near real-time, LADAR system that uses no mechanical moving components and can be used to improve a helicopter pilot’s situational awareness in reduced visual cue environments.

PHASE II: Develop a prototype LADAR that will demonstrate near-real-time imaging and demonstrate a scalable concept that can be further developed into a robust concept demonstrator suitable for installation on helicopters. Performance specifications have not yet been developed, but expect the laser to be class I eye-safe, with a field-of-regard of at least +/- 30 degrees. Image update rate on a suitable display should approach 10 hz, but there can be some relief if it can be shown that the update rate is limited by processing power and/or operating system.

PHASE III: Develop a functional prototype LADAR suitable for installation on a military helicopter. The LADAR system can be a strap-in system with a cockpit mounted display that provides near-real-time imagery of the LZ below the aircraft. Additionally, the system will provided Vg and AGL information that is extracted from the functional prototype LADAR. As in Phase II, the LADAR must be class I eye-safe and the objective display update rate is 10 hz. The system will be demonstrated in actual brown-out conditions at a government selected landing site.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: This technology is applicable to all helicopter operations, both military and civilian. In particular, helicopter operations that require flight in close quarter conditions or reduced visual cue (day or night) environments such as police operations, news agency operations, fire-fighting, off-shore oil platform operations, geological surveys, etc, would benefit significantly with this technology. Additionally, fixed wing commercial operations could benefit from the use of this technology to enhance situational awareness during airport landings in conditions of limited visibility.

REFERENCES:
1. M. Toyoshima, F. Fidler, M. Pfennighauer, W. R. Leeb, "Two-dimensional Optical Beam Deflector Operated by Wavelength Tuning", Proceeding Optical Society of America, 2006.

2. J. Stockley, X. Xia, T. Ewing, S. Serati, "Liquid Crystal Optical Phase Modulators for Beam Steering", Mat. Res. Soc. Symp. Proc. Vol. 709 © 2002 Materials Research Society

3. O. Steinvall, T. Carlsson, C. Gronwall, H. Larsson, P. Andersson, L. Klasen, "Laser Based 3-D Imaging; New Capabilities for Optical Sensing", FOI-R-0856 Technical Report, Swedish Defence Research Agency, 2003

4. P. McManamon, W. Thompson, "Phased Array of Phased Arrays (PAPA) Laser Systems Architecture", Fiber and Integrated Optics, 22:79-88, 2003

KEYWORDS: LADAR; Optical Phased Array; Brown-out; Laser; Landing Aid; Laser Beam-Steering; Situational Awareness

** TOPIC AUTHOR (TPOC) **

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