Remote measurement of near-surface physical properties using optically smart surfaces

A method for remotely measuring one or more physical characteristics at or near the surface of a curved object, said method comprising;

• a. conformally affixing to said surface of said object a thin flexible film, at least a portion of which contains a hologram, said hologram forming in response to illumination by electromagnetic radiation an image which varies in a predetermined way in response to variations in said physical characteristics at or near said surface, said hologram being further defined as including an image of two beams intersecting at or above the surface of said film,
• b. illuminating said film with one or more address beams of coherent radiation producing at or above said surface a sample volume containing a plurality of interference fringes usable to measure the Laser Doppler Velocity of particles flowing through said volume,
• c. collecting at least a portion of radiation diffracted from said film in response to said illumination, and
• d. analyzing said collected radiation to determine variations in said physical characteristics at or near said object surface that cause a variation in said collected radiation.

A method for remotely measuring one or more physical characteristics at or near the surface of a curved object, said method comprising;

• a. conformally affixing to said surface of said object a thin, flexible film elastically deformable in concert with deformations of said surface of said object, at least a portion of said film which contains a hologram, said hologram forming in response to illumination by electromagnetic radiation an image which varies in a predetermined way in response to variations in said physical characteristics at or near said object surface, said hologram including a first uniaxial grating, whereby first deformations of said object surface parallel to said grating vector, i.e., perpendicular to lines comprising said grating, alters the spatial frequency of said grating, thereby causing a beam diffracted from said hologram in response to illumination by a coherent address beam to produce a change in fringe pattern proportional to strain of said object surface,
• b. illuminating said film with one or more address beams of coherent radiation, said coherent radiation illuminating said film comprising two address beams laterally spaced apart from one another incident upon laterally spaced apart locations of said film, said incident address beams producing two separate diffracted beams that interfere with one another to produce a fringe pattern proportional to the difference in spatial frequencies of said grating at said locations of said film,
• c. collecting at least a portion of radiation diffracted from said film in response to said illumination, and
• d. analyzing said collected radiation to determine variations in said physical characteristics at or near said object surface that cause a variation in said collected radiation.

An apparatus for remotely measuring a physical characteristic at or near the curved surface of an object, said object having a thin film affixed to at least a portion of said surface of said object, said film being elastically deformable in concert with deformations of said surface of said object, said film having formed in at least a portion thereof a hologram containing a first uniaxial grating, whereby first deformations of said object surface perpendicular to lines comprising said first grating alter spacing between said lines, thereby causing a beam diffracted from said hologram in response to illumination by said address beam to produce a diffracted fringe pattern which changes in proportion to strain of said object surface, said apparatus comprising,

• a. means for illuminating said film with one or more address beams effective in producing one or more diffracted beams from said grating, said means for illuminating said film being further defined as comprising two address beams laterally spaced apart from one another incident upon laterally spaced apart locations of said film, said incident address beams being adapted to produce two separate diffracted beams that interfere with one another to produce a fringe pattern proportional to the difference in grating spacing at said locations of said film,
• b. means for collecting at least a portion of said diffracted beams, and
• c. signal processing means for analyzing said collected portion of said diffracted beams, whereby physical characteristics at or near said object surface may be remotely determined.