Abstract

Intrinsic performance limits of noncontacting fiber lever displacement measuring systems are quantitatively described. Generalized relationships linking displacement detection limit, frequency response, dynamic range, linearity, and working distance to fiber diameter, illumination irradiance and coupling angle, photo-detector characteristics, and reflection and transmission losses were obtained by analysis and confirmed by measurement. Both procedures showed performance limits to be functions of the square root of the flux density coupled into the target-illuminating fiber(s) by the electroluminescent source. Displacement detection and bandwidth limits achievable with tungsten or LED sources were in the 2 × 10−11 to 2×10-12m/Hz and MHz, range respectively. A basis for optimizing levers for different applications and determination of intrinsic performance limits is provided.

© 1979 Optical Society of America

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References

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  1. J. A. Simpson, Rev. Sci. Instrum. 42, 1371 (1971).
    [CrossRef]
  2. A. W. Hartman, F. W. Roseberry, J. A. Simpson, Opt. Eng. 12, 95 (1973).
    [CrossRef]
  3. J. Simon, Appl. Opt. 9, 2337 (1970).
    [CrossRef] [PubMed]
  4. R. G. Goldman, W. R. Marklein, in Third Annual Symposium on Non-Destructive Testing of Missiles and Aircraft Components (Society for Non-Destructive Testing, San Antonio, Texas, 1963). Also described in U.S. Patent3,263,087 (1966),
  5. B. O. Kelly, Laser Focus, 11, (3), 38 (March1976).
  6. R. V. Jones, F. C. S. Richards, J. Sci. Instrum. 36, 90 (1959).
    [CrossRef]
  7. Frank’s disclosure preceded Kissinger’s by less than 2 weeks. While both disclosed the concept, Frank only claimed usages relating to diaphragm-type pressure transducers, thus leaving other usages (excepting reflectance compensation methods granted Kissinger) in the public domain.
  8. C. D. Kissinger, Fiber Optic Proximity Probe, U.S. Patent3,327,584 (27Sept.1967).
  9. W. E. Frank, Detection and Measurement Device having a Small Flexible Fiber Transmission Line (U.S. Patent3,273,447, 20Sept.1966).
  10. R. Hokenberg, Exptl. Mech. 7, 19A (June1967).
    [CrossRef]
  11. G. J. Jako, L. A. Maroti, S. Holly, J. Acoust. Soc. Am. 41, 1578 (1967).
    [CrossRef]
  12. R. O. Cook, T. Konishi, C. W. Hamm, A. H. Yankwich, J. Acoust. Soc. Am. 58, Suppl. 1, 447 (1975).
  13. R. O. Cook, T. Konishi, C. W. Hamm, A. H. Yankwich, L. Royster, J. Acoust. Soc. Am. 58, Suppl. 1, 448 (1975).
  14. R. O. Cook, “The Response of Guinea Pig Ears to Pure Tones, Speech and other Complex Waveforms Imparted Acoustically and by Ossicular Chain Coupled Piezoelectric Type Transducers,” unpublished Ph.D. dissertation, North Carolina State University, Raleigh (1976); available from University Microfilms, Ann Arbor, Michigan.
  15. J. Sanford, Des. News, 10, 8 (Feb.3, 1975).
  16. W. R. Moore, Am. Mach. 110, (18), 65 (Aug.29, 1966).
  17. J. Thorson, D. C. S. White, IEEE Trans. Biomed. Eng. BME-22, 293 (1975).
    [CrossRef]
  18. R. H. Pahler, A. S. Roberts, Am. Soc. Mech. Eng. Pap. 75-WA/DE-8 (1975).
  19. H. Matsumoto et al., Jpn. Med. Electron. Biol. Eng. 15, 480 (1977).
  20. A. Rameriz et al., J. Appl. Physiol. 26, 679 (1969).
  21. R. Cook, C. Hamm, A. Akay, J. Acoust. Soc. Am. 64, Suppl. 1, EE3 (1978).
  22. F. J. Crispi, G. C. Maling, A. W. Rzant, J. Res. Dev. 16, 307 (1972).
  23. The “Fotonic Sensor,” a trademark of Mechanical Technology, Inc., Latham, New York.
  24. C. Menadier, C. Kissinger, H. Adkins, Instrum. Control Syst. 40, 114 (1967).
  25. Sound pressure levels associated with normal speech (45–75 dB) produce ossicular chain displacements on the order of 1–30 Å.26 Some nerve impulses produce similar displacements.27
  26. M. Lawrence, in Sensorineural Hearing Processes and Disorders, A. B. Graham, Ed. (Little Brown, Boston, 1967).
  27. B. C. Hill, E. D. Schubert, M. A. Nokes, R. P. Michaelson, Science 196, 426 (1977).
    [CrossRef] [PubMed]
  28. Coupling of collimated rays is only one of several methods by which rays traveling at the same angle to a fiber’s longitudinal axis may be produced. Others include creating microbends in fibers by applying pressure and appropriately blocking the light leaving condensing lenses.
  29. A term P¯DC = PDC/PMDC is the ratio of power subtended at arbitrary target distances (PDC) to maximum subtended power (PMDC); differentiation of this term and Eq. (5) lead to Eq. (12), since DS = dy/dPDC by definition.
  30. S. Larach, Photoelectronic Devices and Materials (Van Nostrand, Princeton, N.J., 1965), Chap. 5.
  31. An analysis of the sources of intrinsic noise in various photodiode-op-amp combinations may be found in Refs. 32 and 33, supplemented by specific manufacturers literature.
  32. A. E. Barelli, Electron. Des. 15, 68 (July1973).
  33. P. H. Wendland, Electronics, 44 (11), 50 (May1971).
  34. An exception occurs where the luminous spectrum of the source extends well into the IR, i.e., beyond the response range of silicon or germanium detectors and at very low frequencies (<10 Hz) where 1/f intrinsic noise begins to exceed shot noise in most electronic devices.
  35. M. Madden, Opt. Spectra 12 (11), 51 (1978).
  36. D. B. Keck, Appl. Opt. 13, 1882 (1974).
    [CrossRef] [PubMed]
  37. , “Plastic Fiber Optics,” in Encyclopedia of Polymer Science and Technology (Wiley, New York, 1971), Vol. 15, p. 202.
  38. A trademark of Galite, Inc., Wallingford, Conn.
  39. W. J. Smith, Modern Optical Systems (McGraw-Hill, New York, 1966), p. 182.
  40. J. P. Wittke, M. Ettenberg, H. Kressel, RCA Rev. 37, 159 (1976).
  41. T. P. Lee, C. A. Burrus, IEEE J. Quantum. Electron. QE-8, 370 (1972).
  42. G. Tenchio, Electron. Lett. 12, 562 (1976).
    [CrossRef]
  43. J. L. Paoli, IEEE J. Quantum. Electron. QE-II, 276 (1975).
    [CrossRef]
  44. A. E. Barelli, report to the Deafness Research Foundation, 366 Madison Avenue, New York, N.Y. 10017 (August1974).
  45. H. Kressel, Appl. Opt. 17, 2233 (1978).
    [CrossRef] [PubMed]
  46. Working distance, standoff distance, and equilibrium distance are used interchangeably. Each refers to the fiber tip-to-target distance when the target is at rest. This distance is usually set to correspond to the approximate center of the dynamic range of the vibrating target.
  47. C. D. Kissinger, R. L. Smith in Proceedings of the Electro-Optical Systems Design Conference, 1973 (I.S.C.M., 222 W. Adams St., Chicago, Ill. 60606).
  48. C. D. Kissinger, B. Howland, Fiber Optic Displacement Measurement Apparatus, U.S. Patent3,940,608 (24Feb.1976).
  49. G. E. Moss, L. R. Miler, R. L. Forward, Appl. Opt. 10, 2495 (1971).
    [CrossRef] [PubMed]

1978 (3)

R. Cook, C. Hamm, A. Akay, J. Acoust. Soc. Am. 64, Suppl. 1, EE3 (1978).

M. Madden, Opt. Spectra 12 (11), 51 (1978).

H. Kressel, Appl. Opt. 17, 2233 (1978).
[CrossRef] [PubMed]

1977 (2)

B. C. Hill, E. D. Schubert, M. A. Nokes, R. P. Michaelson, Science 196, 426 (1977).
[CrossRef] [PubMed]

H. Matsumoto et al., Jpn. Med. Electron. Biol. Eng. 15, 480 (1977).

1976 (3)

B. O. Kelly, Laser Focus, 11, (3), 38 (March1976).

J. P. Wittke, M. Ettenberg, H. Kressel, RCA Rev. 37, 159 (1976).

G. Tenchio, Electron. Lett. 12, 562 (1976).
[CrossRef]

1975 (6)

J. L. Paoli, IEEE J. Quantum. Electron. QE-II, 276 (1975).
[CrossRef]

R. O. Cook, T. Konishi, C. W. Hamm, A. H. Yankwich, J. Acoust. Soc. Am. 58, Suppl. 1, 447 (1975).

R. O. Cook, T. Konishi, C. W. Hamm, A. H. Yankwich, L. Royster, J. Acoust. Soc. Am. 58, Suppl. 1, 448 (1975).

J. Sanford, Des. News, 10, 8 (Feb.3, 1975).

J. Thorson, D. C. S. White, IEEE Trans. Biomed. Eng. BME-22, 293 (1975).
[CrossRef]

R. H. Pahler, A. S. Roberts, Am. Soc. Mech. Eng. Pap. 75-WA/DE-8 (1975).

1974 (1)

1973 (2)

A. E. Barelli, Electron. Des. 15, 68 (July1973).

A. W. Hartman, F. W. Roseberry, J. A. Simpson, Opt. Eng. 12, 95 (1973).
[CrossRef]

1972 (2)

F. J. Crispi, G. C. Maling, A. W. Rzant, J. Res. Dev. 16, 307 (1972).

T. P. Lee, C. A. Burrus, IEEE J. Quantum. Electron. QE-8, 370 (1972).

1971 (3)

P. H. Wendland, Electronics, 44 (11), 50 (May1971).

G. E. Moss, L. R. Miler, R. L. Forward, Appl. Opt. 10, 2495 (1971).
[CrossRef] [PubMed]

J. A. Simpson, Rev. Sci. Instrum. 42, 1371 (1971).
[CrossRef]

1970 (1)

1969 (1)

A. Rameriz et al., J. Appl. Physiol. 26, 679 (1969).

1967 (3)

C. Menadier, C. Kissinger, H. Adkins, Instrum. Control Syst. 40, 114 (1967).

R. Hokenberg, Exptl. Mech. 7, 19A (June1967).
[CrossRef]

G. J. Jako, L. A. Maroti, S. Holly, J. Acoust. Soc. Am. 41, 1578 (1967).
[CrossRef]

1966 (1)

W. R. Moore, Am. Mach. 110, (18), 65 (Aug.29, 1966).

1959 (1)

R. V. Jones, F. C. S. Richards, J. Sci. Instrum. 36, 90 (1959).
[CrossRef]

Adkins, H.

C. Menadier, C. Kissinger, H. Adkins, Instrum. Control Syst. 40, 114 (1967).

Akay, A.

R. Cook, C. Hamm, A. Akay, J. Acoust. Soc. Am. 64, Suppl. 1, EE3 (1978).

Barelli, A. E.

A. E. Barelli, Electron. Des. 15, 68 (July1973).

A. E. Barelli, report to the Deafness Research Foundation, 366 Madison Avenue, New York, N.Y. 10017 (August1974).

Burrus, C. A.

T. P. Lee, C. A. Burrus, IEEE J. Quantum. Electron. QE-8, 370 (1972).

Cook, R.

R. Cook, C. Hamm, A. Akay, J. Acoust. Soc. Am. 64, Suppl. 1, EE3 (1978).

Cook, R. O.

R. O. Cook, T. Konishi, C. W. Hamm, A. H. Yankwich, J. Acoust. Soc. Am. 58, Suppl. 1, 447 (1975).

R. O. Cook, T. Konishi, C. W. Hamm, A. H. Yankwich, L. Royster, J. Acoust. Soc. Am. 58, Suppl. 1, 448 (1975).

R. O. Cook, “The Response of Guinea Pig Ears to Pure Tones, Speech and other Complex Waveforms Imparted Acoustically and by Ossicular Chain Coupled Piezoelectric Type Transducers,” unpublished Ph.D. dissertation, North Carolina State University, Raleigh (1976); available from University Microfilms, Ann Arbor, Michigan.

Crispi, F. J.

F. J. Crispi, G. C. Maling, A. W. Rzant, J. Res. Dev. 16, 307 (1972).

Ettenberg, M.

J. P. Wittke, M. Ettenberg, H. Kressel, RCA Rev. 37, 159 (1976).

Forward, R. L.

Frank, W. E.

W. E. Frank, Detection and Measurement Device having a Small Flexible Fiber Transmission Line (U.S. Patent3,273,447, 20Sept.1966).

Goldman, R. G.

R. G. Goldman, W. R. Marklein, in Third Annual Symposium on Non-Destructive Testing of Missiles and Aircraft Components (Society for Non-Destructive Testing, San Antonio, Texas, 1963). Also described in U.S. Patent3,263,087 (1966),

Hamm, C.

R. Cook, C. Hamm, A. Akay, J. Acoust. Soc. Am. 64, Suppl. 1, EE3 (1978).

Hamm, C. W.

R. O. Cook, T. Konishi, C. W. Hamm, A. H. Yankwich, J. Acoust. Soc. Am. 58, Suppl. 1, 447 (1975).

R. O. Cook, T. Konishi, C. W. Hamm, A. H. Yankwich, L. Royster, J. Acoust. Soc. Am. 58, Suppl. 1, 448 (1975).

Hartman, A. W.

A. W. Hartman, F. W. Roseberry, J. A. Simpson, Opt. Eng. 12, 95 (1973).
[CrossRef]

Hill, B. C.

B. C. Hill, E. D. Schubert, M. A. Nokes, R. P. Michaelson, Science 196, 426 (1977).
[CrossRef] [PubMed]

Hokenberg, R.

R. Hokenberg, Exptl. Mech. 7, 19A (June1967).
[CrossRef]

Holly, S.

G. J. Jako, L. A. Maroti, S. Holly, J. Acoust. Soc. Am. 41, 1578 (1967).
[CrossRef]

Howland, B.

C. D. Kissinger, B. Howland, Fiber Optic Displacement Measurement Apparatus, U.S. Patent3,940,608 (24Feb.1976).

Jako, G. J.

G. J. Jako, L. A. Maroti, S. Holly, J. Acoust. Soc. Am. 41, 1578 (1967).
[CrossRef]

Jones, R. V.

R. V. Jones, F. C. S. Richards, J. Sci. Instrum. 36, 90 (1959).
[CrossRef]

Keck, D. B.

Kelly, B. O.

B. O. Kelly, Laser Focus, 11, (3), 38 (March1976).

Kissinger, C.

C. Menadier, C. Kissinger, H. Adkins, Instrum. Control Syst. 40, 114 (1967).

Kissinger, C. D.

C. D. Kissinger, B. Howland, Fiber Optic Displacement Measurement Apparatus, U.S. Patent3,940,608 (24Feb.1976).

C. D. Kissinger, R. L. Smith in Proceedings of the Electro-Optical Systems Design Conference, 1973 (I.S.C.M., 222 W. Adams St., Chicago, Ill. 60606).

C. D. Kissinger, Fiber Optic Proximity Probe, U.S. Patent3,327,584 (27Sept.1967).

Konishi, T.

R. O. Cook, T. Konishi, C. W. Hamm, A. H. Yankwich, J. Acoust. Soc. Am. 58, Suppl. 1, 447 (1975).

R. O. Cook, T. Konishi, C. W. Hamm, A. H. Yankwich, L. Royster, J. Acoust. Soc. Am. 58, Suppl. 1, 448 (1975).

Kressel, H.

H. Kressel, Appl. Opt. 17, 2233 (1978).
[CrossRef] [PubMed]

J. P. Wittke, M. Ettenberg, H. Kressel, RCA Rev. 37, 159 (1976).

Larach, S.

S. Larach, Photoelectronic Devices and Materials (Van Nostrand, Princeton, N.J., 1965), Chap. 5.

Lawrence, M.

M. Lawrence, in Sensorineural Hearing Processes and Disorders, A. B. Graham, Ed. (Little Brown, Boston, 1967).

Lee, T. P.

T. P. Lee, C. A. Burrus, IEEE J. Quantum. Electron. QE-8, 370 (1972).

Madden, M.

M. Madden, Opt. Spectra 12 (11), 51 (1978).

Maling, G. C.

F. J. Crispi, G. C. Maling, A. W. Rzant, J. Res. Dev. 16, 307 (1972).

Marklein, W. R.

R. G. Goldman, W. R. Marklein, in Third Annual Symposium on Non-Destructive Testing of Missiles and Aircraft Components (Society for Non-Destructive Testing, San Antonio, Texas, 1963). Also described in U.S. Patent3,263,087 (1966),

Maroti, L. A.

G. J. Jako, L. A. Maroti, S. Holly, J. Acoust. Soc. Am. 41, 1578 (1967).
[CrossRef]

Matsumoto, H.

H. Matsumoto et al., Jpn. Med. Electron. Biol. Eng. 15, 480 (1977).

Menadier, C.

C. Menadier, C. Kissinger, H. Adkins, Instrum. Control Syst. 40, 114 (1967).

Michaelson, R. P.

B. C. Hill, E. D. Schubert, M. A. Nokes, R. P. Michaelson, Science 196, 426 (1977).
[CrossRef] [PubMed]

Miler, L. R.

Moore, W. R.

W. R. Moore, Am. Mach. 110, (18), 65 (Aug.29, 1966).

Moss, G. E.

Nokes, M. A.

B. C. Hill, E. D. Schubert, M. A. Nokes, R. P. Michaelson, Science 196, 426 (1977).
[CrossRef] [PubMed]

Pahler, R. H.

R. H. Pahler, A. S. Roberts, Am. Soc. Mech. Eng. Pap. 75-WA/DE-8 (1975).

Paoli, J. L.

J. L. Paoli, IEEE J. Quantum. Electron. QE-II, 276 (1975).
[CrossRef]

Rameriz, A.

A. Rameriz et al., J. Appl. Physiol. 26, 679 (1969).

Richards, F. C. S.

R. V. Jones, F. C. S. Richards, J. Sci. Instrum. 36, 90 (1959).
[CrossRef]

Roberts, A. S.

R. H. Pahler, A. S. Roberts, Am. Soc. Mech. Eng. Pap. 75-WA/DE-8 (1975).

Roseberry, F. W.

A. W. Hartman, F. W. Roseberry, J. A. Simpson, Opt. Eng. 12, 95 (1973).
[CrossRef]

Royster, L.

R. O. Cook, T. Konishi, C. W. Hamm, A. H. Yankwich, L. Royster, J. Acoust. Soc. Am. 58, Suppl. 1, 448 (1975).

Rzant, A. W.

F. J. Crispi, G. C. Maling, A. W. Rzant, J. Res. Dev. 16, 307 (1972).

Sanford, J.

J. Sanford, Des. News, 10, 8 (Feb.3, 1975).

Schubert, E. D.

B. C. Hill, E. D. Schubert, M. A. Nokes, R. P. Michaelson, Science 196, 426 (1977).
[CrossRef] [PubMed]

Simon, J.

Simpson, J. A.

A. W. Hartman, F. W. Roseberry, J. A. Simpson, Opt. Eng. 12, 95 (1973).
[CrossRef]

J. A. Simpson, Rev. Sci. Instrum. 42, 1371 (1971).
[CrossRef]

Smith, R. L.

C. D. Kissinger, R. L. Smith in Proceedings of the Electro-Optical Systems Design Conference, 1973 (I.S.C.M., 222 W. Adams St., Chicago, Ill. 60606).

Smith, W. J.

W. J. Smith, Modern Optical Systems (McGraw-Hill, New York, 1966), p. 182.

Tenchio, G.

G. Tenchio, Electron. Lett. 12, 562 (1976).
[CrossRef]

Thorson, J.

J. Thorson, D. C. S. White, IEEE Trans. Biomed. Eng. BME-22, 293 (1975).
[CrossRef]

Wendland, P. H.

P. H. Wendland, Electronics, 44 (11), 50 (May1971).

White, D. C. S.

J. Thorson, D. C. S. White, IEEE Trans. Biomed. Eng. BME-22, 293 (1975).
[CrossRef]

Wittke, J. P.

J. P. Wittke, M. Ettenberg, H. Kressel, RCA Rev. 37, 159 (1976).

Yankwich, A. H.

R. O. Cook, T. Konishi, C. W. Hamm, A. H. Yankwich, L. Royster, J. Acoust. Soc. Am. 58, Suppl. 1, 448 (1975).

R. O. Cook, T. Konishi, C. W. Hamm, A. H. Yankwich, J. Acoust. Soc. Am. 58, Suppl. 1, 447 (1975).

Am. Mach. (1)

W. R. Moore, Am. Mach. 110, (18), 65 (Aug.29, 1966).

Am. Soc. Mech. Eng. Pap. 75-WA/DE-8 (1)

R. H. Pahler, A. S. Roberts, Am. Soc. Mech. Eng. Pap. 75-WA/DE-8 (1975).

Appl. Opt. (4)

Des. News (1)

J. Sanford, Des. News, 10, 8 (Feb.3, 1975).

Electron. Des. (1)

A. E. Barelli, Electron. Des. 15, 68 (July1973).

Electron. Lett. (1)

G. Tenchio, Electron. Lett. 12, 562 (1976).
[CrossRef]

Electronics (1)

P. H. Wendland, Electronics, 44 (11), 50 (May1971).

Exptl. Mech. (1)

R. Hokenberg, Exptl. Mech. 7, 19A (June1967).
[CrossRef]

IEEE J. Quantum. Electron. (2)

J. L. Paoli, IEEE J. Quantum. Electron. QE-II, 276 (1975).
[CrossRef]

T. P. Lee, C. A. Burrus, IEEE J. Quantum. Electron. QE-8, 370 (1972).

IEEE Trans. Biomed. Eng. (1)

J. Thorson, D. C. S. White, IEEE Trans. Biomed. Eng. BME-22, 293 (1975).
[CrossRef]

Instrum. Control Syst. (1)

C. Menadier, C. Kissinger, H. Adkins, Instrum. Control Syst. 40, 114 (1967).

J. Acoust. Soc. Am. (4)

R. Cook, C. Hamm, A. Akay, J. Acoust. Soc. Am. 64, Suppl. 1, EE3 (1978).

G. J. Jako, L. A. Maroti, S. Holly, J. Acoust. Soc. Am. 41, 1578 (1967).
[CrossRef]

R. O. Cook, T. Konishi, C. W. Hamm, A. H. Yankwich, J. Acoust. Soc. Am. 58, Suppl. 1, 447 (1975).

R. O. Cook, T. Konishi, C. W. Hamm, A. H. Yankwich, L. Royster, J. Acoust. Soc. Am. 58, Suppl. 1, 448 (1975).

J. Appl. Physiol. (1)

A. Rameriz et al., J. Appl. Physiol. 26, 679 (1969).

J. Res. Dev. (1)

F. J. Crispi, G. C. Maling, A. W. Rzant, J. Res. Dev. 16, 307 (1972).

J. Sci. Instrum. (1)

R. V. Jones, F. C. S. Richards, J. Sci. Instrum. 36, 90 (1959).
[CrossRef]

Jpn. Med. Electron. Biol. Eng. (1)

H. Matsumoto et al., Jpn. Med. Electron. Biol. Eng. 15, 480 (1977).

Laser Focus (1)

B. O. Kelly, Laser Focus, 11, (3), 38 (March1976).

Opt. Eng. (1)

A. W. Hartman, F. W. Roseberry, J. A. Simpson, Opt. Eng. 12, 95 (1973).
[CrossRef]

Opt. Spectra (1)

M. Madden, Opt. Spectra 12 (11), 51 (1978).

RCA Rev. (1)

J. P. Wittke, M. Ettenberg, H. Kressel, RCA Rev. 37, 159 (1976).

Rev. Sci. Instrum. (1)

J. A. Simpson, Rev. Sci. Instrum. 42, 1371 (1971).
[CrossRef]

Science (1)

B. C. Hill, E. D. Schubert, M. A. Nokes, R. P. Michaelson, Science 196, 426 (1977).
[CrossRef] [PubMed]

Other (20)

Coupling of collimated rays is only one of several methods by which rays traveling at the same angle to a fiber’s longitudinal axis may be produced. Others include creating microbends in fibers by applying pressure and appropriately blocking the light leaving condensing lenses.

A term P¯DC = PDC/PMDC is the ratio of power subtended at arbitrary target distances (PDC) to maximum subtended power (PMDC); differentiation of this term and Eq. (5) lead to Eq. (12), since DS = dy/dPDC by definition.

S. Larach, Photoelectronic Devices and Materials (Van Nostrand, Princeton, N.J., 1965), Chap. 5.

An analysis of the sources of intrinsic noise in various photodiode-op-amp combinations may be found in Refs. 32 and 33, supplemented by specific manufacturers literature.

The “Fotonic Sensor,” a trademark of Mechanical Technology, Inc., Latham, New York.

Sound pressure levels associated with normal speech (45–75 dB) produce ossicular chain displacements on the order of 1–30 Å.26 Some nerve impulses produce similar displacements.27

M. Lawrence, in Sensorineural Hearing Processes and Disorders, A. B. Graham, Ed. (Little Brown, Boston, 1967).

An exception occurs where the luminous spectrum of the source extends well into the IR, i.e., beyond the response range of silicon or germanium detectors and at very low frequencies (<10 Hz) where 1/f intrinsic noise begins to exceed shot noise in most electronic devices.

, “Plastic Fiber Optics,” in Encyclopedia of Polymer Science and Technology (Wiley, New York, 1971), Vol. 15, p. 202.

A trademark of Galite, Inc., Wallingford, Conn.

W. J. Smith, Modern Optical Systems (McGraw-Hill, New York, 1966), p. 182.

R. G. Goldman, W. R. Marklein, in Third Annual Symposium on Non-Destructive Testing of Missiles and Aircraft Components (Society for Non-Destructive Testing, San Antonio, Texas, 1963). Also described in U.S. Patent3,263,087 (1966),

Frank’s disclosure preceded Kissinger’s by less than 2 weeks. While both disclosed the concept, Frank only claimed usages relating to diaphragm-type pressure transducers, thus leaving other usages (excepting reflectance compensation methods granted Kissinger) in the public domain.

C. D. Kissinger, Fiber Optic Proximity Probe, U.S. Patent3,327,584 (27Sept.1967).

W. E. Frank, Detection and Measurement Device having a Small Flexible Fiber Transmission Line (U.S. Patent3,273,447, 20Sept.1966).

R. O. Cook, “The Response of Guinea Pig Ears to Pure Tones, Speech and other Complex Waveforms Imparted Acoustically and by Ossicular Chain Coupled Piezoelectric Type Transducers,” unpublished Ph.D. dissertation, North Carolina State University, Raleigh (1976); available from University Microfilms, Ann Arbor, Michigan.

Working distance, standoff distance, and equilibrium distance are used interchangeably. Each refers to the fiber tip-to-target distance when the target is at rest. This distance is usually set to correspond to the approximate center of the dynamic range of the vibrating target.

C. D. Kissinger, R. L. Smith in Proceedings of the Electro-Optical Systems Design Conference, 1973 (I.S.C.M., 222 W. Adams St., Chicago, Ill. 60606).

C. D. Kissinger, B. Howland, Fiber Optic Displacement Measurement Apparatus, U.S. Patent3,940,608 (24Feb.1976).

A. E. Barelli, report to the Deafness Research Foundation, 366 Madison Avenue, New York, N.Y. 10017 (August1974).

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Figures (15)

Fig. 1
Fig. 1

Schematic of a basic seven-fiber optic lever. Section AA taken at bundle exit/return plane shows exit and reflected patterns at this plane. Area of return fibers subtended by reflected light is proportional to target distance; modulated area enclosed by dashed lines is proportional to target vibratory motion.

Fig. 2
Fig. 2

Cross sections through seven-fiber bundle showing the relationship between illumination exit angle (ϕ), fiber radius (x0), and reflected illumination radius (q); y = (qx0)/(2 tanϕ). Solid line in both sections is leading edge of ring (radius q) reflected from stationary target; dotted lines (dq) are (exaggerated) minimum and maximum values subtended from a vibrating target.

Fig. 3
Fig. 3

Optic ray geometry associated with ideal fiber, uniangular ray optic lever, and reflective target. Under assumption of ray optics, the irradiance of the bright spot located in the center of the target (at B) is seen to be equal to the emittance exiting the illuminate fiber while the remaining power uniformly illuminates the dimmer area. Illumination from the dimmer portion is reflected onto the return fiber(s) plane; illumination from the bright spot is reflected back into the illuminate fiber. At target distances greater than E, reflected rays are no longer subtended by return fibers.

Fig. 4
Fig. 4

Geometry associated with geometric (area) sensitivity of uniangular optic lever with negligible cladding thickness. The subtended area A of the return fiber may be determined as a function of the reflected illumination radius by trigonometry or by direct integration using polar coordinates.

Fig. 5
Fig. 5

Return fiber normalized subtended area, illumination irradiance, and subtended power as functions of the ratio (k) of the reflected illumination radius (q) to fiber radius (x0). Subtended power is the product of subtended area and irradiance. The bold and double-bold portions of the power curve show the maximum range within which the ratio of subtended power to k differs from linearity by less than 10% and by less than 1%, respectively.

Fig. 6
Fig. 6

Photodiode-operational amplifier connection diagram for transimpedance, photoconductive operation. Reverse biasing of the photodiode (+V) extends frequency response. Capacitor (C f ) is necessary to prevent instability in very high frequency systems.

Fig. 7
Fig. 7

Illumination-produced shot noise voltage, op-amp intrinsic noise voltage, and optical detection limit at optimal transimpedance gain (see text) for radiometric power on the diode. Intrinsic and shot noise values (circles) were obtained from a hybrid device (Silicon Detector Corp., SD-441-41-21-261). Other appropriately selected (see text) hybrid and separate component devices produced similar results. Dashed line is continuation of theoretical shot noise values.

Fig. 8
Fig. 8

Displacement detection limit vs illuminate fiber irradiance for 14° uniangular lever, including packing fraction losses but excluding transmission and reflection losses. Limits are referenced to center of quasi-linear positive and negative slope ranges. Normal beam irradiances of He–Ne and YAG lasers are shown for order-of-magnitude reference purposes; irradiance increases on the order of several orders of magnitude can be obtained by focusing these sources.

Fig. 9
Fig. 9

Elementary seven-fiber optic lever parametric relationships for uniangular input, ideal illuminate fiber and reflector. Subtended power, displacement sensitivity, and displacement detection limit are denoted by P, DS, and DDL, respectively. Ordinate and abscissa scales have been generalized to permit determination of actual values for any given lever (see text). The values a and a′, b and b′ denote the maximum ranges for 10% and 1% nonlinearity, respectively; the corresponding Δk ranges are 0.47, 0.70, 0.16, and 0.23, respectively.

Fig. 10
Fig. 10

Subtended power vs equilibrium distance for 14° and 20° uniangular and 0–20° isotropic levers. Numbers on brackets denote the 10% nonlinearity limits in multiples of fiber radius xo. The positive slopes of the 14° uniangular and 0–20° isotropic levers characteristic relationships are practically coincident.

Fig. 11
Fig. 11

Measured intensity exiting 200-μm Galite 4000-type fiber used as illuminate fiber. Fiber was illuminated at 12° coupling angle by an He–Ne laser (divergence ~1 mrad). Data were obtained by rotating a pinhole-photodetector combination in the far field and averaging the results to account for maxima and minima associated with coherence effects.

Fig. 12
Fig. 12

Calculated vs measured subtended power for quasi-uniangular insertion (12°) lever whose illuminate fiber output intensity is shown in Fig. 11. Solid line shows relationship computer-calculated from the data of Fig. 11 (see text); dashed line shows same relationship measured by using nonrotating micrometer face as target. Experimental data were obtained by terminating photosensor and linear variable displacement transducer (LVDT) outputs at Y and X terminals of an XY recorder.

Fig. 13
Fig. 13

Measured fiber output intensity (solid line) when incandescent filament was imaged on entrance face of 200-μm Galite 4000-type fiber by an optical system whose N.A. was greater than that of the fiber (nominally 0.35). Data were obtained by rotating a pinhole-photodetector combination in the far field. Published output intensity (dashed line) of typical commercially available light emitting diode/fiber pigtail is shown for reference purposes.

Fig. 14
Fig. 14

Calculated vs measured subtended power for the quasi-isotropic exit intensity shown in Fig. 13. Solid line shows calculated relationship (see text); dashed line shows relationship measured by using micrometer face as target. Experimental data were obtained by terminating photosensor and LVDT outputs at Y and X terminals of an XY recorder.

Fig. 15
Fig. 15

Normalized measured power vs working distance of a basic seven-fiber lever with and without optical extender (see text). Illumination source was a He–Ne laser.

Equations (20)

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y = ( q - x 0 ) / ( 2 tan ϕ ) ,
d A = 2 π q d q .
d y / d A = 1 / ( 2 π q 2 tan ϕ ) .
d y / d A = 1 / ( 2 π k x 0 2 tan ϕ ) ,
y = [ ( k - 1 ) x 0 ] / ( 2 tan ϕ ) .
A = ( x 0 / 2 ) [ Ψ k 2 + sin - 1 ( k sin Ψ ) - 2 k sin Ψ ]             k 5 ,
A = ( x 0 / 2 ) [ Ψ k 2 + π - sin - 1 ( k sin Ψ ) - 2 k sin Ψ ]             k 5 ,
A = ( x 0 / 2 ) [ Ψ k 2 + sin - 1 ( k sin Ψ ) - k l sin Ψ ]             k ( 1 + l 2 ) 1 / 2 ,
A = ( x 0 / 2 ) [ Ψ k 2 + π - sin - 1 ( k sin Ψ ) - k l sin Ψ ]             k ( 1 + l 2 ) 1 / 2 ,
I k = L I 0 [ ( 5 - k ) / ( 4 k + 4 ) ]             k 3 ,
I k = L I 0 [ 1 / ( 4 k - 4 ) ]             k 3 ,
D S = S ˜ [ x 0 / ( 2 tan ϕ P M D C ) ] .
i s h = [ P D C ( r ) ( 2 e ) ( B W ) ] 1 / 2 ,
( i sig ) / r = ( i s h ) / r = P sig .
E noise = i s h R f ,
E sig = i sig R f .
D D L = D ˜ x 0 tan ϕ [ ( e ) ( B W ) 2 r P M D C ] 1 / 2 .
L R = ( Δ k x 0 ) / ( 2 tan ϕ ) ,
D R = Δ k D ˜ ( P M D C r 2 e B W ) 1 / 2 ,
D R = Δ k x 0 D ˜ ( Z π r I 0 2 e B W ) 1 / 2 ,

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