The system includes a fixed wavelength laser and a tunable wavelength laser
as inputs. Respective input optical fibers receive the inputs and transmit
them to a first position proximate a location on a surface to be
interrogated. Respective fiber coupling optics deliver the inputs to the
interrogated location on the surface. The inputs are alignable so that
their surface locations of optical illumination overlap on the
interrogated location. Output fiber coupling optics receives a reflected
output resulting from a three-wave mixing process occurring at the
interrogated location. An output optical fiber receives an output of the
output fiber coupling optics and transmits the output to a desired
position from the interrogated location. An output sensor system receives
an output of the output optical fiber and collects, analyzes and
interprets the output of the output optical fiber, wherein the fixed
wavelength laser, tunable wavelength laser and the output sensor system
may be disposed at desired distances and angles from the interrogated
location.
