SBIR-STTR Award

We propose a novel SWIR/MWIR imaging system targeted for deployment at geosynchronous orbits. The new system is based on interferometric principles, is scalable, light-weight, and uses easily replicable inexpensive optics. The optics, detectors, and interferometric signal processing principles draw heavily on decades of experience in ground-based astronomical applications designed to yield the highest sensitivity and resolution in the IR with cost-effective optical solutions. The system is designed to fit within a 2 foot cube. Light weight is assured by building the infrastructure from carbon fiber reinforced polymer (CFRP) which has been qualified in space. The same material is employed for the primary mirrors of the interferometric elements in a replication process. Thus, not only are they light weight, but they are cheap, easy to fabricate, and readily produced in quantity. They also demonstrate excellent optical quality. The design allows for up to six interferometer elements to be combined in an arrangement that comes close to providing the sensitivity of a filled aperture while remaining much more compact. Dual imaging cameras behind the interferometer allow broad wavelength coverage in the atmospheric windows across the SWIR and MWIR bands. Beam combination is by conventional glass optics held rigidly in place. Processing of the interferometer signals to remove the instrumental point-spread function uses a light-weight on-board processor that runs in real time.

Benefit:
Anticipated benefits are a light-weight space based sensor for SWIR/MWIR imaging that is inexpensive, easy and rapid to manufacture, and can readily be deployed on commercial buses. The principles developed under this program are easily transferred to airborne platforms to provide larger apertures with greater resolution and sensitivity than current technology without increasing the system size, weight, and power demands. Ground-based platforms for surveillance and security will also benefit from the same advantages.

Research Objectives: 1) Quantify the size, weight, power consumption and cost of flight units of the Space-based InfraRed Imaging Interferometer (SIRII) sensor. 2) Quantify the fundamental advantages of the interferometric approach in comparison to conventional sensor design. 3) Quantify the impact of disadvantages of the interferometer. 4) Establish the steps required to mature the design to a flight unit in Phase III, and the additional cost and schedule required to get there. Technical Approach: Construct a full-scale prototype of the SIRII sensor in light-weight composite materials using a low-cost SWIR focal plane array. Validate manufacturing techniques, assembly tooling and procedures, and test methodology. Demonstrate performance of the prototype. Through detailed modeling and analysis anchored by measurements from the prototype, establish expected on-orbit performance in fulfillment of the sensor?s primary mission, as well as any enhancements to the design required for flight hardware. In addition, investigate the use of the SIRII design in other applications: from space (e.g. Space Situational Awareness (SSA), in particular within the GEO belt, forest fire detection, agricultural water and crop management) and from airborne platforms (e.g. anti-access/area denial, smuggling interdiction).

Benefit:
Anticipated Impact and Outcome: The primary mission of the SIRII sensor is the detection of missile plumes from orbit. For that purpose, the Phase I study has shown that application of the principles of optical interferometry has both practical and performance advantages over conventional sensor designs. The main outcomes of the Phase II work will be a quantitative demonstration of those advantages in prototype hardware, and a sound understanding of the cost, time, and effort required to proceed to a fully qualified flight system. The overall structure of the SBIR program, including the breakout to commercial products in Phase III, is summarized in Figure 1. SIRII is to be commercialized for defense and civil security applications.

Keywords:
Imaging Interferometer, Missile Plume Detection, Ir Sensor, Hosted Payload, Optical Interferometry, Space-Based Sensor