Abstract

A microcontroller-based digital signal processing system developed for use with fiber-optic sensors for measuring pressure in internal combustion engines is described. A single distributed feedback laser source provides optical power for four interferometric sensors. The laser current is repetitively modulated so that its optical frequency is nearly a linear function of time over most of a cycle. The interferometer phase shift is proportional to the elapsed time from the initiation of a sawtooth until the sensor output signal level crosses a threshold value proportional to the laser output power. This elapsed time, assumed to vary linearly with the combustion chamber pressure, is determined by the use of a digital timer–counter. The system has been used with fiber Fabry–Perot interferometer transducers for in-cylinder pressure measurement on a four-cylinder gasoline-powered engine.

© 1995 Optical Society of America

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  1. A. Dandridge, A. B. Tveten, T. G. Giallorenzi, “Homodyne demodulation scheme for fiber optic sensors using phase generated carrier,” IEEE J. Quantum Electron. QE-18, 1647–1653 (1982).
    [CrossRef]
  2. A. Dandridge, A. B. Tveten, A. D. Kersey, A. M. Yurek, “Multiplexing of interferometric sensors using phase carrier techniques,” J. Lightwave Technol. LT-5, 947–952 (1987).
    [CrossRef]
  3. D. A. Jackson, A. D. Kersey, M. Corke, J. D. C. Jones, “Pseudoheterodyne detection scheme for optical interferometers,” Electron. Lett. 18, 1081–1083 (1982).
    [CrossRef]
  4. I. J. Bush, D. R. Sherman, “High performance interferometric demodulation techniques,” in Fiber Optic and Laser Sensors X, R. P. DePaula, E. Udd, eds., Proc. Soc. Photo-Opt. Instrum. Eng.1795, 412–420 (1992).
  5. Y. Yeh, J. H. Lee, C. E. Lee, H. F. Taylor, “In-line Fabry–Perot interferometric temperature sensor with digital signal processing,” in Fiber Optic and Laser Sensors IX, R. P. DePaula, E. Udd, eds., Proc. Soc. Photo-Opt. Instrum. Eng.1584, 72–78 (1991).
  6. J. J. Alcoz, C. E. Lee, H. F. Taylor, “Embedded fiber-optic Fabry–Perot ultrasound sensor,” IEEE Trans. Ultrason. Ferroelectr. Freq. Control 17, 302–306 (1990).
    [CrossRef]
  7. S. Kobayashi, Y. Yamamoto, M. Ito, T. Kimura, “Direct frequency modulation in AlGaAs semiconductor lasers,” IEEE J. Quantum Electron. QE-18, 528–535 (1982).
  8. G. Jacobsen, H. Olesen, F. Birkedahl, “Current/frequency modulation characteristics for directly modulated optical frequency modulated injection lasers at 830 μm and 1.3 μm,” Electron. Lett. 18, 874–876 (1982).
    [CrossRef]
  9. L. Goldberg, H. F. Taylor, J. F. Weller, “Time dependent thermal effects in current modulated semiconductor lasers,” Electron. Lett. 17, 497–499 (1981).
    [CrossRef]
  10. C. E. Lee, H. F. Taylor, “Interferometric optical fibre sensors using internal mirrors,” Electron. Lett. 24, 193–194 (1988).
    [CrossRef]
  11. R. A. Atkins, C. E. Lee, H. F. Taylor, “New fiber optic in-cylinder pressure sensor,” Diesel Gas Turb. Worldwide, Apr.1995.
  12. R. A. Atkins, J. H. Gardner, W. N. Gibler, C. E. Lee, M. D. Oakland, M. O. Spears, V. P. Swenson, H. F. Taylor, J. J. McCoy, G. Beshouri, “Fiber-optic pressure sensors for internal combustion engines,” Appl. Opt. 33, 1315–1320 (1994).
    [CrossRef] [PubMed]

1995 (1)

R. A. Atkins, C. E. Lee, H. F. Taylor, “New fiber optic in-cylinder pressure sensor,” Diesel Gas Turb. Worldwide, Apr.1995.

1994 (1)

1990 (1)

J. J. Alcoz, C. E. Lee, H. F. Taylor, “Embedded fiber-optic Fabry–Perot ultrasound sensor,” IEEE Trans. Ultrason. Ferroelectr. Freq. Control 17, 302–306 (1990).
[CrossRef]

1988 (1)

C. E. Lee, H. F. Taylor, “Interferometric optical fibre sensors using internal mirrors,” Electron. Lett. 24, 193–194 (1988).
[CrossRef]

1987 (1)

A. Dandridge, A. B. Tveten, A. D. Kersey, A. M. Yurek, “Multiplexing of interferometric sensors using phase carrier techniques,” J. Lightwave Technol. LT-5, 947–952 (1987).
[CrossRef]

1982 (4)

D. A. Jackson, A. D. Kersey, M. Corke, J. D. C. Jones, “Pseudoheterodyne detection scheme for optical interferometers,” Electron. Lett. 18, 1081–1083 (1982).
[CrossRef]

A. Dandridge, A. B. Tveten, T. G. Giallorenzi, “Homodyne demodulation scheme for fiber optic sensors using phase generated carrier,” IEEE J. Quantum Electron. QE-18, 1647–1653 (1982).
[CrossRef]

S. Kobayashi, Y. Yamamoto, M. Ito, T. Kimura, “Direct frequency modulation in AlGaAs semiconductor lasers,” IEEE J. Quantum Electron. QE-18, 528–535 (1982).

G. Jacobsen, H. Olesen, F. Birkedahl, “Current/frequency modulation characteristics for directly modulated optical frequency modulated injection lasers at 830 μm and 1.3 μm,” Electron. Lett. 18, 874–876 (1982).
[CrossRef]

1981 (1)

L. Goldberg, H. F. Taylor, J. F. Weller, “Time dependent thermal effects in current modulated semiconductor lasers,” Electron. Lett. 17, 497–499 (1981).
[CrossRef]

Alcoz, J. J.

J. J. Alcoz, C. E. Lee, H. F. Taylor, “Embedded fiber-optic Fabry–Perot ultrasound sensor,” IEEE Trans. Ultrason. Ferroelectr. Freq. Control 17, 302–306 (1990).
[CrossRef]

Atkins, R. A.

Beshouri, G.

Birkedahl, F.

G. Jacobsen, H. Olesen, F. Birkedahl, “Current/frequency modulation characteristics for directly modulated optical frequency modulated injection lasers at 830 μm and 1.3 μm,” Electron. Lett. 18, 874–876 (1982).
[CrossRef]

Bush, I. J.

I. J. Bush, D. R. Sherman, “High performance interferometric demodulation techniques,” in Fiber Optic and Laser Sensors X, R. P. DePaula, E. Udd, eds., Proc. Soc. Photo-Opt. Instrum. Eng.1795, 412–420 (1992).

Corke, M.

D. A. Jackson, A. D. Kersey, M. Corke, J. D. C. Jones, “Pseudoheterodyne detection scheme for optical interferometers,” Electron. Lett. 18, 1081–1083 (1982).
[CrossRef]

Dandridge, A.

A. Dandridge, A. B. Tveten, A. D. Kersey, A. M. Yurek, “Multiplexing of interferometric sensors using phase carrier techniques,” J. Lightwave Technol. LT-5, 947–952 (1987).
[CrossRef]

A. Dandridge, A. B. Tveten, T. G. Giallorenzi, “Homodyne demodulation scheme for fiber optic sensors using phase generated carrier,” IEEE J. Quantum Electron. QE-18, 1647–1653 (1982).
[CrossRef]

Gardner, J. H.

Giallorenzi, T. G.

A. Dandridge, A. B. Tveten, T. G. Giallorenzi, “Homodyne demodulation scheme for fiber optic sensors using phase generated carrier,” IEEE J. Quantum Electron. QE-18, 1647–1653 (1982).
[CrossRef]

Gibler, W. N.

Goldberg, L.

L. Goldberg, H. F. Taylor, J. F. Weller, “Time dependent thermal effects in current modulated semiconductor lasers,” Electron. Lett. 17, 497–499 (1981).
[CrossRef]

Ito, M.

S. Kobayashi, Y. Yamamoto, M. Ito, T. Kimura, “Direct frequency modulation in AlGaAs semiconductor lasers,” IEEE J. Quantum Electron. QE-18, 528–535 (1982).

Jackson, D. A.

D. A. Jackson, A. D. Kersey, M. Corke, J. D. C. Jones, “Pseudoheterodyne detection scheme for optical interferometers,” Electron. Lett. 18, 1081–1083 (1982).
[CrossRef]

Jacobsen, G.

G. Jacobsen, H. Olesen, F. Birkedahl, “Current/frequency modulation characteristics for directly modulated optical frequency modulated injection lasers at 830 μm and 1.3 μm,” Electron. Lett. 18, 874–876 (1982).
[CrossRef]

Jones, J. D. C.

D. A. Jackson, A. D. Kersey, M. Corke, J. D. C. Jones, “Pseudoheterodyne detection scheme for optical interferometers,” Electron. Lett. 18, 1081–1083 (1982).
[CrossRef]

Kersey, A. D.

A. Dandridge, A. B. Tveten, A. D. Kersey, A. M. Yurek, “Multiplexing of interferometric sensors using phase carrier techniques,” J. Lightwave Technol. LT-5, 947–952 (1987).
[CrossRef]

D. A. Jackson, A. D. Kersey, M. Corke, J. D. C. Jones, “Pseudoheterodyne detection scheme for optical interferometers,” Electron. Lett. 18, 1081–1083 (1982).
[CrossRef]

Kimura, T.

S. Kobayashi, Y. Yamamoto, M. Ito, T. Kimura, “Direct frequency modulation in AlGaAs semiconductor lasers,” IEEE J. Quantum Electron. QE-18, 528–535 (1982).

Kobayashi, S.

S. Kobayashi, Y. Yamamoto, M. Ito, T. Kimura, “Direct frequency modulation in AlGaAs semiconductor lasers,” IEEE J. Quantum Electron. QE-18, 528–535 (1982).

Lee, C. E.

R. A. Atkins, C. E. Lee, H. F. Taylor, “New fiber optic in-cylinder pressure sensor,” Diesel Gas Turb. Worldwide, Apr.1995.

R. A. Atkins, J. H. Gardner, W. N. Gibler, C. E. Lee, M. D. Oakland, M. O. Spears, V. P. Swenson, H. F. Taylor, J. J. McCoy, G. Beshouri, “Fiber-optic pressure sensors for internal combustion engines,” Appl. Opt. 33, 1315–1320 (1994).
[CrossRef] [PubMed]

J. J. Alcoz, C. E. Lee, H. F. Taylor, “Embedded fiber-optic Fabry–Perot ultrasound sensor,” IEEE Trans. Ultrason. Ferroelectr. Freq. Control 17, 302–306 (1990).
[CrossRef]

C. E. Lee, H. F. Taylor, “Interferometric optical fibre sensors using internal mirrors,” Electron. Lett. 24, 193–194 (1988).
[CrossRef]

Y. Yeh, J. H. Lee, C. E. Lee, H. F. Taylor, “In-line Fabry–Perot interferometric temperature sensor with digital signal processing,” in Fiber Optic and Laser Sensors IX, R. P. DePaula, E. Udd, eds., Proc. Soc. Photo-Opt. Instrum. Eng.1584, 72–78 (1991).

Lee, J. H.

Y. Yeh, J. H. Lee, C. E. Lee, H. F. Taylor, “In-line Fabry–Perot interferometric temperature sensor with digital signal processing,” in Fiber Optic and Laser Sensors IX, R. P. DePaula, E. Udd, eds., Proc. Soc. Photo-Opt. Instrum. Eng.1584, 72–78 (1991).

McCoy, J. J.

Oakland, M. D.

Olesen, H.

G. Jacobsen, H. Olesen, F. Birkedahl, “Current/frequency modulation characteristics for directly modulated optical frequency modulated injection lasers at 830 μm and 1.3 μm,” Electron. Lett. 18, 874–876 (1982).
[CrossRef]

Sherman, D. R.

I. J. Bush, D. R. Sherman, “High performance interferometric demodulation techniques,” in Fiber Optic and Laser Sensors X, R. P. DePaula, E. Udd, eds., Proc. Soc. Photo-Opt. Instrum. Eng.1795, 412–420 (1992).

Spears, M. O.

Swenson, V. P.

Taylor, H. F.

R. A. Atkins, C. E. Lee, H. F. Taylor, “New fiber optic in-cylinder pressure sensor,” Diesel Gas Turb. Worldwide, Apr.1995.

R. A. Atkins, J. H. Gardner, W. N. Gibler, C. E. Lee, M. D. Oakland, M. O. Spears, V. P. Swenson, H. F. Taylor, J. J. McCoy, G. Beshouri, “Fiber-optic pressure sensors for internal combustion engines,” Appl. Opt. 33, 1315–1320 (1994).
[CrossRef] [PubMed]

J. J. Alcoz, C. E. Lee, H. F. Taylor, “Embedded fiber-optic Fabry–Perot ultrasound sensor,” IEEE Trans. Ultrason. Ferroelectr. Freq. Control 17, 302–306 (1990).
[CrossRef]

C. E. Lee, H. F. Taylor, “Interferometric optical fibre sensors using internal mirrors,” Electron. Lett. 24, 193–194 (1988).
[CrossRef]

L. Goldberg, H. F. Taylor, J. F. Weller, “Time dependent thermal effects in current modulated semiconductor lasers,” Electron. Lett. 17, 497–499 (1981).
[CrossRef]

Y. Yeh, J. H. Lee, C. E. Lee, H. F. Taylor, “In-line Fabry–Perot interferometric temperature sensor with digital signal processing,” in Fiber Optic and Laser Sensors IX, R. P. DePaula, E. Udd, eds., Proc. Soc. Photo-Opt. Instrum. Eng.1584, 72–78 (1991).

Tveten, A. B.

A. Dandridge, A. B. Tveten, A. D. Kersey, A. M. Yurek, “Multiplexing of interferometric sensors using phase carrier techniques,” J. Lightwave Technol. LT-5, 947–952 (1987).
[CrossRef]

A. Dandridge, A. B. Tveten, T. G. Giallorenzi, “Homodyne demodulation scheme for fiber optic sensors using phase generated carrier,” IEEE J. Quantum Electron. QE-18, 1647–1653 (1982).
[CrossRef]

Weller, J. F.

L. Goldberg, H. F. Taylor, J. F. Weller, “Time dependent thermal effects in current modulated semiconductor lasers,” Electron. Lett. 17, 497–499 (1981).
[CrossRef]

Yamamoto, Y.

S. Kobayashi, Y. Yamamoto, M. Ito, T. Kimura, “Direct frequency modulation in AlGaAs semiconductor lasers,” IEEE J. Quantum Electron. QE-18, 528–535 (1982).

Yeh, Y.

Y. Yeh, J. H. Lee, C. E. Lee, H. F. Taylor, “In-line Fabry–Perot interferometric temperature sensor with digital signal processing,” in Fiber Optic and Laser Sensors IX, R. P. DePaula, E. Udd, eds., Proc. Soc. Photo-Opt. Instrum. Eng.1584, 72–78 (1991).

Yurek, A. M.

A. Dandridge, A. B. Tveten, A. D. Kersey, A. M. Yurek, “Multiplexing of interferometric sensors using phase carrier techniques,” J. Lightwave Technol. LT-5, 947–952 (1987).
[CrossRef]

Appl. Opt. (1)

Diesel Gas Turb. Worldwide (1)

R. A. Atkins, C. E. Lee, H. F. Taylor, “New fiber optic in-cylinder pressure sensor,” Diesel Gas Turb. Worldwide, Apr.1995.

Electron. Lett. (4)

D. A. Jackson, A. D. Kersey, M. Corke, J. D. C. Jones, “Pseudoheterodyne detection scheme for optical interferometers,” Electron. Lett. 18, 1081–1083 (1982).
[CrossRef]

G. Jacobsen, H. Olesen, F. Birkedahl, “Current/frequency modulation characteristics for directly modulated optical frequency modulated injection lasers at 830 μm and 1.3 μm,” Electron. Lett. 18, 874–876 (1982).
[CrossRef]

L. Goldberg, H. F. Taylor, J. F. Weller, “Time dependent thermal effects in current modulated semiconductor lasers,” Electron. Lett. 17, 497–499 (1981).
[CrossRef]

C. E. Lee, H. F. Taylor, “Interferometric optical fibre sensors using internal mirrors,” Electron. Lett. 24, 193–194 (1988).
[CrossRef]

IEEE J. Quantum Electron. (2)

S. Kobayashi, Y. Yamamoto, M. Ito, T. Kimura, “Direct frequency modulation in AlGaAs semiconductor lasers,” IEEE J. Quantum Electron. QE-18, 528–535 (1982).

A. Dandridge, A. B. Tveten, T. G. Giallorenzi, “Homodyne demodulation scheme for fiber optic sensors using phase generated carrier,” IEEE J. Quantum Electron. QE-18, 1647–1653 (1982).
[CrossRef]

IEEE Trans. Ultrason. Ferroelectr. Freq. Control (1)

J. J. Alcoz, C. E. Lee, H. F. Taylor, “Embedded fiber-optic Fabry–Perot ultrasound sensor,” IEEE Trans. Ultrason. Ferroelectr. Freq. Control 17, 302–306 (1990).
[CrossRef]

J. Lightwave Technol. (1)

A. Dandridge, A. B. Tveten, A. D. Kersey, A. M. Yurek, “Multiplexing of interferometric sensors using phase carrier techniques,” J. Lightwave Technol. LT-5, 947–952 (1987).
[CrossRef]

Other (2)

I. J. Bush, D. R. Sherman, “High performance interferometric demodulation techniques,” in Fiber Optic and Laser Sensors X, R. P. DePaula, E. Udd, eds., Proc. Soc. Photo-Opt. Instrum. Eng.1795, 412–420 (1992).

Y. Yeh, J. H. Lee, C. E. Lee, H. F. Taylor, “In-line Fabry–Perot interferometric temperature sensor with digital signal processing,” in Fiber Optic and Laser Sensors IX, R. P. DePaula, E. Udd, eds., Proc. Soc. Photo-Opt. Instrum. Eng.1584, 72–78 (1991).

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Figures (7)

Fig. 1
Fig. 1

Frequency versus time for a sawtooth waveform as described by Eq. (5).

Fig. 2
Fig. 2

Temporal dependence of P out and P th. The time at which the sawtooth ramp begins is t n , and a time at which the two curves cross is t cn . In this case, in which several such crossings occur (indicated by the vertical dotted lines), one particular crossing is selected by the microcontroller and used for the phase shift determination. For example, t cn might be determined as the first crossing for tt n > 100 μs for which P out is increasing with time. In (a) the temporal extent of the plot exceeds one modulation cycle. In (b) the information in (a) is replotted on an expanded time scale, and the effect of a change in ϕ m on the crossing time is indicated.

Fig. 3
Fig. 3

FFPI sensor for measuring the pressure in an internal combustion engine.

Fig. 4
Fig. 4

Engine-pressure measurement system.

Fig. 5
Fig. 5

Schematic diagram of the signal processor and optoelectronic interfaces. Filled arrows are electrical connections and unfilled arrows are optical paths.

Fig. 6
Fig. 6

Measured phase shift versus temperature for a FFPI sensor. The linearity of this plot confirms the linearity of the laser chirp over a phase shift of 2π rad (one fringe).

Fig. 7
Fig. 7

Pressure versus time for a four-cylinder test engine determined by the use of the arrangement of Fig. 4.

Equations (12)

Equations on this page are rendered with MathJax. Learn more.

P out = P 1 ( 1 + k + cos ϕ ) ,
ϕ = ϕ m + ϕ s ,
ϕ s = 2 π Δ L v / c ,
ϕ m = cos - 1 [ ( P out - P 1 - k P 1 ) / P 1 ] - ϕ s .
v = v 0 + α ( t - t n ) ,             t n t < t n + 1 ,             n = integer ,
Δ ϕ s = 2 π Δ L α T / c ,
P th = β P 1 ( t ) ,
ϕ c = cos - 1 ( β - 1 - k ) .
ϕ m = ϕ c - ( 2 π Δ L / c ) [ v 0 + α ( t c n - t n ) ] ,             t n t c n < t n + 1 ,
Δ T ( τ ) = - t F ( t - τ ) I ( τ ) δ τ ,
I ( t ) = I 0 ln [ 1 + ( t - t n ) / Δ ] ,             t n t < t n + 1 ,             n = integer ,
Δ J / J = ( 2 e B / J ) 1 / 2 ,

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