Long-Range Laser Vibrometer for Target Identification

MetroLaser proposes to interface a laser Doppler vibrometer (LDV) sensor to a phased array telescope (PAT) for long-range vibration and target identification measurements and presents a work plan to demonstrate the feasibility of this technique. LDV systems are well suited for long-range interrogation of vibrational signatures, and they have been shown to work at standoff distances of several kilometers. Unfortunately, LDV have two significant limitations that impact their measurement sensitivity in practical environments: 1) they experience significant signal deterioration when the target is moving, and 2) a turbulent atmosphere deteriorates its signal sensitivity, especially at shorter wavelengths. In this proposal, we discuss strategies to mitigate both of these problems; and we show ways to develop a long-range LDV for target identification that is compact and rugged. The Phase I work will consist of both analyses and proof-of-concept experiments to evaluate the feasibility of using coherent LDV at short wavelengths for long ranges. BENEFIT: The proposed system will fill a market need for a long-range laser vibrometer. Presently, there are no viable commercial off-the-shelf, long-range LDV systems that operate on arbitrary surfaces at distances of about 50 m and above. Furthermore, there are no commercial LDV systems that operate at the eye-safe wavelength of 1.55 microns. Market inputs indicate that there is a significant need for a long-range LDV like the one proposed here; that is, a system that can operate on targets of arbitrary reflectivity and that is capable of measuring several locations simultaneously. Specific commercial and/or military sectors include remote vehicle inspection, bridge inspection, inspection of electrical transformers, and remote inspection of historical buildings.