Optical Interferometry with Flexible Coherent Fiber Bundle for Measuring Deposits or Contamination on Surfaces and Inside Tubes

A new measuring/cleaning method for closed surfaces (pipes) applicable to removing contaminants (oil films, fungus, rust) from NASA instruments and spacecraft is being proposed.  This technique relies on a combination of a practical single-beam Holographic in-line interferometry (HILI) and Coherent fringe projection (CFP) techniques in one set-up with modification needed to work inside closed surfaces of tubes and pipes. Additionally, a unified approach for modeling of both HILI and CFP that is suitable for remote characterization of contaminants inside these structures is also being proposed.  This modeling approach is based on the concept of the coherent superposition of partial interference patterns.  Then, it will be shown that the combination of laser-induced fluorescence and laser induced optical trapping and evaporation may provide more accurate detection of contaminants and a new method of laser-induced cleaning of contamination. Based on previous experience with oil contamination, a modified version of fringe projection interferometry to monitor contamination in the pipes, which will include a flexible coherent optical fiber bundle to allow inspection of pipe’s inner space will be used. Flexible coherent optical fiber bundle allow to transmit images of contaminated spots from the enclosed surface inside the pipes and tanks. Coherent fringe projection (CFP) techniques proved to be efficient in our previous efforts involving non-contact metrology of microstructured objects.

The contaminant removal from the pipes will be patterned along the lines of our previous work on removal of oil films from water.  For cleaning of closed surfaces (pipes, tanks) flexible optical fibers will be used. Laser evaporated volatile fractions will be removed by air pumps and they may be condensed for further utilization.

The proposed efforts will develop the basis of an important tool, a tool that when fully developed will be extremely useful for NASA scientists in monitoring oil drilling related activities.

This project involves a demonstration for a new environmentally safe and accurate cleaning method for removing contaminants (oil films, fungi,) in enclosed areas such as pipes, tanks, and tubes.  It relies on a combination of techniques such as, Laser-induced fluorescence (LIF), Optical trapping (OT), Holographic in-line interferometry (HILI), Coherent fringe projection (CFP), and Optical evaporation (OE).   To enable inspection and operation of the method inside enclosed surfaces, the techniques will operate with a flexible coherent optical fiber bundle.  A unified approach for modeling both HILI and CFP will be developed to demonstrate that these techniques are suitable for accurate remote characterization of contaminants.