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  • Techniques in Broadband Interferometry

    A Compilation of Patents 1997-2002

    David J. Erskine

    Lawrence Livermore National Laboratory

    December 2003 UCRL-TR-201695

  • This document was prepared as an account of work sponsored by an agency of the United States

    Government. Neither the United States Government nor the University of California nor any of theiremployees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the

    accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, orrepresents that its use would not infringe privately owned rights. Reference herein to any specific

    commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does notnecessarily constitute or imply its endorsement, recommendation, or favoring by the United States

    Government or the University of California. The views and opinions of authors expressed herein do not

    necessarily state or reflect those of the United States Government or the University of California, and shallnot be used for advertising or product endorsement purposes.

    This work was performed under the auspices of the U.S. Department of Energy by University of California,Lawrence Livermore National Laboratory under Contract W-7405-Eng-48.

    Available fromLawrence Livermore National Laboratory

    Technical Information Department's Digital Libraryhttp://www.llnl.gov/library/

  • Contents

    Preface ix

    Introduction x

    1 White Light Velocity Interferometer 1-1

    2 White Light Velocity Interferometer, continued 2-1

    3 Noise-Pair Velocity and Range Echo-Location System 3-1

    4 Multichannel Heterodyning for Wideband Interferometry,Correlation and Signal Processing 4-1

    5 Single and Double Superimposing Interferometer Systems 5-1

    6 Combined Dispersive/Interference Spectroscopy forProducing a Vector Spectrum 6-1

    7 Examples in the Scientific Literature 7-1

    Contents in detail

    1 White Light Velocity Interferometer 1-1

    I BACKGROUND OF THE INVENTION 1-1

    A Field of the Invention . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1

    B Description of Related Art . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1

    1 Superimposing interferometers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1

    2 Velocity sensitivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

    3 Using sources with higher power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3

    i

  • II SUMMARY OF THE INVENTION 1-4

    III DETAILED DESCRIPTION OF THE INVENTION 1-4

    A Explanation in Time-domain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4B Explanation in Frequency-domain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5

    1 Velocity sensitivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-52 Interferometry at multiple wavelengths . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6

    C Other topics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-61 Transverse velocity component . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-62 Relation to Optical Coherence Tomography . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6

    D Complementary outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-61 Push-pull use of complementary outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-62 Practicalities using complementary outputs . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7

    E Example application measuring fluid flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-71 Range of allowed velocities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-8

    F Theory regarding the superimposing condition . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-81 Distorting elements tolerated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-8

    IV Three modes of measuring fringes 1-9

    A Single detecting channel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-9B Multiple detecting channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-9

    1 Wavelength distributed system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-92 Delay distributed system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-103 Narrow-band illumination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-104 Chirped illumination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-11

    V Interferometer design classes 1-12

    A Michelson vs. Fabry-Perot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-12B Superimposition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-13

    1 Tolerance for smear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-13C Fabry-Perot Interferometers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-14D Superimposing delays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-14

    1 Etalon delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-152 Delays using real imaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-153 Lens delays using virtual imaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-154 Minimizing chromatic aberrations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-165 Creating negative and positive delays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-166 Computing the net delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-177 Use with optical waveguide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-178 Why put image at mirror plane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-189 Use with sound or microwaves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1810 One-dimensional configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1811 For matter waves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-19

    ii

  • VI Example apparatus using retro-reflected light 1-19

    Acknowledgments 1-19

    VII CLAIMS 1-20

    2 White Light Velocity Interferometer, continued 2-1

    I CLAIMS 2-1

    3 Noise-Pair Velocity and Range Echo-Location System 3-1

    I Introduction 3-1

    A Field of the Technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1

    B Description of the Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1

    II SUMMARY OF THE INVENTION 3-3

    III DETAILED DESCRIPTION OF THE INVENTION 3-3

    A Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3

    B About the interferometers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4

    C Measuring a Doppler Shift . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4

    D Velocity from Phase Shift . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5

    E Equivalence to an Autocorrelation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5

    F Targets Separated from Clutter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6

    G Clutter Cancellation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-8

    H Plotting the Autocorrelation vs Wavelength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-9

    I Sensing Target Albedo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-9

    J Pulse Repetition and Echolocation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-9

    K Explanation in Frequency Domain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-11

    1 Undesired Kind of Illumination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-12

    2 Comparison to Matched Filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-12

    L Expected Practice for Radar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-13

    1 Moving Reference Frame . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-13

    M Several Embodiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-13

    1 Ultrasound . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-14

    2 General Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-14

    N Simultaneous Multiple Banded Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-14

    1 Means for Achieving Long Delays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-14

    O Optical Embodiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-17

    iii

  • Acknowledgments 3-19

    IV CLAIMS 3-21

    4 Multichannel Heterodyning for Wideband Interferometry,Correlation and Signal P

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