Multi-Aperture Differential Image Motion Monitor

Physical Sciences Inc. (PSI) will develop a compact multi-aperture differential image motion monitor (MA-DIMM) to measure two-dimensional (spatial), range-resolved marine turbulence. The proposed MA-DIMM will be integrated with a 3-band picosecond laser and provide 3D spatial profiles of the Fried parameter, r0, and the structure constant, Cn2, as a function of range. The DIMM technique is based on a diffractive beam splitting optic and range-gated focal plane array (FPA). A four-aperture MA-DIMM is modeled to achieve 20 discrete range measurements within the threshold operational range of 5 km with a Cn2 error of < 10%. The MA-DIMM technique is expected to offer lateral resolutions on the order of the Fried parameter, r0 (i.e. 10s to 100s of cm), range resolutions as low as 1.5 m, and sparse range sampling with = 20 range bins. The Phase I effort has been designed to validate feasibility of the technique through extensive modeling, algorithm development, and characterization of a laboratory breadboard. Successful Phase I will result in design and development of a field-deployable MA-DIMM prototype in the Phase II program.