TECHNOLOGY AREA(S): Electronics, Weapons

ACQUISITION PROGRAM: PMA 299 (ASW) H-60 Helicopter Program

OBJECTIVE: Develop an efficient laser cooling system for heat removal from a laser enclosure system.

DESCRIPTION: Most Naval platforms use a combination of imaging systems with laser emitters for the purpose of real-time active imaging, laser designation, and range finding capabilities. Due to the high output energy requirements from the lasers, there is a need for the development of an additional cooling system for laser enclosures to supplement the conventional closed liquid loop cooler. No interfacing between the primary and secondary cooling systems is necessary. This requirement is mainly driven by the fact that laser head can heat up faster than the rest of the system and ambient temperature of -40�C to 55�C, can be much higher than the internal temperature of the laser enclosure.

The system should be designed to be rugged, compact and lightweight enough to be used in Naval aircraft, both fixed and rotatory wing platforms. It is therefore the goal of this program to seek the development of the cooling system for a power-scalable laser system solution that will meet the size, weight, performance and reliability requirements below while considering component costs for future production of the system.� The proposer should consider this development as the innovative advancement and combination of laser and supporting technologies towards the goals stated below; and their design should focus mainly on cooling the laser head; however, the cooling system must be designed such that it cools down the laser head and minimizes the heat throughout the entire system as specified by the internal temperature requirement.

The performance objectives of the cooling system are;
1. Maintain consistent internal temperature of 25�C with the laser head being cooler than the overall internal temperature at approximately 10�C.
2. Thermal management largely driven by an internal temperature limit of 65�F and the fact that ambient temperature may be significantly higher than the required internal temperature.
3. The cooling system must dissipate heat in the order of ~20KJ.
4. Ability to be ruggedized and packaged to withstand the shock, vibration, pressure, temperature, humidity, electrical power conditions, etc. encountered in a system built for airborne use per MIL-STD-810G
5. Weight of approximately 125 pounds.
6. Physical size of 16 x 15 x102 inches.
7. Reliability: mean time between equipment failure of 300 operating hours.
8. Full Rate Production Cost: Threshold <$50,000; Objective <$15,000 (based on 1000 units).

PHASE I: Define and develop a concept for a viable and robust cooling system solution that meets or exceeds the requirements specified in the description.� Identify technological and reliability challenges of the design approach, and propose viable risk mitigation strategies.� The Phase I effort will include plans to develop a prototype under Phase II.

PHASE II: Design, fabricate, and demonstrate a laser system prototype based on the design from Phase I.� Test and fully characterize the system prototype.

PHASE III DUAL USE APPLICATIONS: Using Phase II test results and Navy feedback, finalize the design, fabricate a ruggedized laser system solution, and assist with efforts to obtain certification for flight on a NAVAIR R&D aircraft.

High-power, pulsed lasers have applications in manufacturing and lithography.� An efficient cooling system for the lasers used for drilling or etching would help stabilize the laser beam divergence and increase the accuracy of the cutting process.

REFERENCES:

1. Tuckerman, D. B. et al. �High Performance Heat Sinking for VLSI.� IEEE Electron Device Letters, May 1981, Vol. 2, Issue 5, pp. 126-129. http://ieeexplore.ieee.org/document/1481851/

2. Bland, T. J. et al. �A Compact High Intensity Cooler (CHIC).� SAE Technical Paper 831127, 13th Intersociety Conference on Environmental Systems, San Francisco, Calif., July 11-13, 1983. https://www.researchgate.net/publication/260903319_A_compact_high_intensity_cooler_CHIC

3. MIL-STD-810G, DEPARTMENT OF DEFENSE TEST METHOD STANDARD: ENVIRONMENTAL ENGINEERING CONSIDERATIONS AND LABORATORY TESTS (31 OCT 2008). http://everyspec.com/MIL-STD/MIL-STD-0800-0899/MIL-STD-810G_12306/

KEYWORDS: Cooling System; Heat Control; Temperature Control; Heat Stability; Designator; Target Marker