Abstract

We present a novel method for low noise, high-speed, real-time spectroscopy to monitor molecular absorption spectra. The system is based on a rapidly swept, narrowband CW Fourier-domain mode-locked (FDML) laser source for spectral encoding in time and an optically time-multiplexed split-pulse data acquisition system for improved noise performance and sensitivity. An acquisition speed of ∼100 kHz, a spectral resolution better than 0.1 nm over a wavelength range of ∼1335–1373 nm and a relative noise level of ∼5 mOD (∼1% minimum detectable base-e absorbance) are achieved. The system is applied for crank-angle-resolved gas thermometry by H2O absorption spectroscopy in an engine motoring at 600 and 900 rpm with a precision of ∼1%. Influences of various noise sources such as laser phase and intensity noise, trigger and synchronization jitter in the electronic detection system, and the accuracy of available H2O absorption databases are discussed.

© 2007 Optical Society of America

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References

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  1. S. T. Sanders, D. W. Mattison, L. Ma, J. B. Jeffries, and R. K. Hanson, "Wavelength-agile diode-laser sensing strategies for monitoring gas properties in optically harsh flows: application in cesium-seeded pulse detonation engine," Opt. Express,  10, (2002) 505-514.
    [PubMed]
  2. M. A. Oehlschlaeger, D. F. Davidson, and R. K. Hanson, "Investigation of the reaction of toluene with molecular oxygen in shock-heated gases," Combust. Flame 147, 195-208 (2006).
    [CrossRef]
  3. F. C. De Lucia, Jr., R. S. Harmon, K. L. McNesby, K. L. WinkelJr., R. J. and A. W. Miziolek, "Laser-induced breakdown spectroscopy analysis of energetic materials," Appl. Opt. 42, 6148-6152 (2003).
    [CrossRef] [PubMed]
  4. A. Suslov, B. K. Sarma, J. B. Ketterson, F. Balakirev, A. Migliori, and A. Lacerda, "Ultrasonic Instrumentation for Measurements in High Magnetic Fields. II. Pulsed Magnetic Fields" in 11th International Conference on Ion Sources, 2005, "Ultrasonic Instrumentation for Measurements in High Magnetic Fields. II. Pulsed Magnetic Fields" (AIP, Caen, France, 2006), pp. 35105-35111.
  5. L. A. Kranendonk, R. Huber, J. G. Fujimoto, and S. T. Sanders, "Wavelength-agile H2O absorption spectrometer for thermometry of general combustion gases," Proc. Combust. Inst. 31, 783-790 (2007).
    [CrossRef]
  6. L. A. Kranendonk, J. W. Walewski, T. Kim, and S. T. Sanders, "Wavelength-agile sensor applied for HCCI engine measurements," Proc. Combust. Inst. 30,1619-1627 (2005).
    [CrossRef]
  7. A. W. Caswell, S. T. Sanders, and M. J. Chiaverini, "Swept-Wavelength Laser Absorption Tomography for Imaging Rocket Plume Gas Properties" in 41st AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit, "Swept-Wavelength Laser Absorption Tomography for Imaging Rocket Plume Gas Properties", (2005).
  8. L. A. Kranendonk and S. T. Sanders, "Optical design in beam steering environments with emphasis on laser transmission measurements," Appl. Opt,  44, (2005) 6762-6772.
    [CrossRef] [PubMed]
  9. R. A. Palmer, J. L. Chao, R. M. Dittmar, V. G. Gregoriou, and S. E. Plunkett, "Investigation of Time-Dependent Phenomena by use of Step-Scan FT-IR" in Symposium on Advanced Infrared Spectroscopy (AIRS), "Investigation of Time-Dependent Phenomena by use of Step-Scan FT-IR," Tokyo, Japan, (1993) 1297-1310.
  10. R. Huber, M. Wojtkowski, and J. G. Fujimoto, "Fourier Domain Mode Locking (FDML): A new laser operating regime and application for optical coherence tomography," Opt. Express 14, 3225-37 (2006).
    [CrossRef] [PubMed]
  11. C. L. Hagen and S. T. Sanders, "Investigation of Multi-species (H2O2 and H2O) Sensing and Thermometry in an HCCI Engine by Wavelength-Agile Absorption Spectroscopy," Meas. Sci. Technol. 18, 1992-1998 (2006).
    [CrossRef]
  12. J. A. Filipa, J. W. Walewski, and S. T. Sanders, University of Wisconsin, 1500 Engineering Dr., Madison, WI 53706, are preparing a manuscript to be called "Optical beating in time-resolved spectroscopy. Part II: Strategies for spectroscopic sensing in the presence of optical beating".
  13. J. W. Walewski, J. A. Filipa, and S. T. Sanders, University of Wisconsin, 1500 Engineering Dr., Madison, WI 53706, are preparing a manuscript to be called "Optical beating of polychromatic light and its impact ontime-resolved spectroscopy. Part I: Theory".
  14. J. W. Goodman, "Some problems involving high-order coherence," in Statistical Optics (John Wiley & Sons, Inc., 1985), pp. 237-250.
  15. M. J. Beran and Jr. G. Parrent, Theory of Partial Coherence, (Society of Photo-Optical Instrumentation Engineers, Palos Verdes Estates, 1974).
  16. S. T. Sanders, "Online thermal beating noise calculator," http://chyp.erc.wisc.edu/tools/thermallight.html.
  17. R. Huber, M. Wojtkowski, K. Taira, J. G. Fujimoto, K. Hsu, "Amplified, frequency swept lasers for frequency domain reflectometry and OCT imaging: design and scaling principles," Opt. Express 13, 3513-3528 (2006).
    [CrossRef]
  18. R. Huber, D. C. Adler, J. G. Fujimoto, "Buffered Fourier domain mode locking: unidirectional swept laser sources for optical coherence tomography imaging at 370,000 lines/s," Opt. Lett. 31, 2975- 2977 (2006).
    [CrossRef] [PubMed]
  19. R. E. Herold, D. E. Foster, J. B. Ghandhi, R. J. Iverson, J. A. Eng, and P. M. Najt, "Fuel unmixedness effects in a gasoline homogeneous charge compression ignition engine," Int. J. Engine Res. 8, 241-257 (2007).
    [CrossRef]
  20. L. A. Kranendonk, A. W. Caswell, and S. T. Sanders, "Robust method for calculating temperature, pressure and absorber mole fraction from broadband spectra," Appl. Opt. 46, 4117-4124 (2007).
    [CrossRef] [PubMed]
  21. R. J. Barber, J. Tennyson, G. J. Harris, and R. N. Tolchenov, "A high-accuracy computed water line list," Monthly Notices of the Royal Astronomical Society 368, 1087-1094 (2006).
    [CrossRef]

2007

L. A. Kranendonk, R. Huber, J. G. Fujimoto, and S. T. Sanders, "Wavelength-agile H2O absorption spectrometer for thermometry of general combustion gases," Proc. Combust. Inst. 31, 783-790 (2007).
[CrossRef]

R. E. Herold, D. E. Foster, J. B. Ghandhi, R. J. Iverson, J. A. Eng, and P. M. Najt, "Fuel unmixedness effects in a gasoline homogeneous charge compression ignition engine," Int. J. Engine Res. 8, 241-257 (2007).
[CrossRef]

L. A. Kranendonk, A. W. Caswell, and S. T. Sanders, "Robust method for calculating temperature, pressure and absorber mole fraction from broadband spectra," Appl. Opt. 46, 4117-4124 (2007).
[CrossRef] [PubMed]

2006

R. J. Barber, J. Tennyson, G. J. Harris, and R. N. Tolchenov, "A high-accuracy computed water line list," Monthly Notices of the Royal Astronomical Society 368, 1087-1094 (2006).
[CrossRef]

R. Huber, M. Wojtkowski, K. Taira, J. G. Fujimoto, K. Hsu, "Amplified, frequency swept lasers for frequency domain reflectometry and OCT imaging: design and scaling principles," Opt. Express 13, 3513-3528 (2006).
[CrossRef]

R. Huber, M. Wojtkowski, and J. G. Fujimoto, "Fourier Domain Mode Locking (FDML): A new laser operating regime and application for optical coherence tomography," Opt. Express 14, 3225-37 (2006).
[CrossRef] [PubMed]

R. Huber, D. C. Adler, J. G. Fujimoto, "Buffered Fourier domain mode locking: unidirectional swept laser sources for optical coherence tomography imaging at 370,000 lines/s," Opt. Lett. 31, 2975- 2977 (2006).
[CrossRef] [PubMed]

M. A. Oehlschlaeger, D. F. Davidson, and R. K. Hanson, "Investigation of the reaction of toluene with molecular oxygen in shock-heated gases," Combust. Flame 147, 195-208 (2006).
[CrossRef]

C. L. Hagen and S. T. Sanders, "Investigation of Multi-species (H2O2 and H2O) Sensing and Thermometry in an HCCI Engine by Wavelength-Agile Absorption Spectroscopy," Meas. Sci. Technol. 18, 1992-1998 (2006).
[CrossRef]

2005

L. A. Kranendonk, J. W. Walewski, T. Kim, and S. T. Sanders, "Wavelength-agile sensor applied for HCCI engine measurements," Proc. Combust. Inst. 30,1619-1627 (2005).
[CrossRef]

L. A. Kranendonk and S. T. Sanders, "Optical design in beam steering environments with emphasis on laser transmission measurements," Appl. Opt,  44, (2005) 6762-6772.
[CrossRef] [PubMed]

2003

2002

Adler, D. C.

Barber, R. J.

R. J. Barber, J. Tennyson, G. J. Harris, and R. N. Tolchenov, "A high-accuracy computed water line list," Monthly Notices of the Royal Astronomical Society 368, 1087-1094 (2006).
[CrossRef]

Caswell, A. W.

Davidson, D. F.

M. A. Oehlschlaeger, D. F. Davidson, and R. K. Hanson, "Investigation of the reaction of toluene with molecular oxygen in shock-heated gases," Combust. Flame 147, 195-208 (2006).
[CrossRef]

De Lucia, F. C.

Eng, J. A.

R. E. Herold, D. E. Foster, J. B. Ghandhi, R. J. Iverson, J. A. Eng, and P. M. Najt, "Fuel unmixedness effects in a gasoline homogeneous charge compression ignition engine," Int. J. Engine Res. 8, 241-257 (2007).
[CrossRef]

Foster, D. E.

R. E. Herold, D. E. Foster, J. B. Ghandhi, R. J. Iverson, J. A. Eng, and P. M. Najt, "Fuel unmixedness effects in a gasoline homogeneous charge compression ignition engine," Int. J. Engine Res. 8, 241-257 (2007).
[CrossRef]

Fujimoto, J. G.

Ghandhi, J. B.

R. E. Herold, D. E. Foster, J. B. Ghandhi, R. J. Iverson, J. A. Eng, and P. M. Najt, "Fuel unmixedness effects in a gasoline homogeneous charge compression ignition engine," Int. J. Engine Res. 8, 241-257 (2007).
[CrossRef]

Hagen, C. L.

C. L. Hagen and S. T. Sanders, "Investigation of Multi-species (H2O2 and H2O) Sensing and Thermometry in an HCCI Engine by Wavelength-Agile Absorption Spectroscopy," Meas. Sci. Technol. 18, 1992-1998 (2006).
[CrossRef]

Hanson, R. K.

Harmon, R. S.

Harris, G. J.

R. J. Barber, J. Tennyson, G. J. Harris, and R. N. Tolchenov, "A high-accuracy computed water line list," Monthly Notices of the Royal Astronomical Society 368, 1087-1094 (2006).
[CrossRef]

Herold, R. E.

R. E. Herold, D. E. Foster, J. B. Ghandhi, R. J. Iverson, J. A. Eng, and P. M. Najt, "Fuel unmixedness effects in a gasoline homogeneous charge compression ignition engine," Int. J. Engine Res. 8, 241-257 (2007).
[CrossRef]

Hsu, K.

Huber, R.

Iverson, R. J.

R. E. Herold, D. E. Foster, J. B. Ghandhi, R. J. Iverson, J. A. Eng, and P. M. Najt, "Fuel unmixedness effects in a gasoline homogeneous charge compression ignition engine," Int. J. Engine Res. 8, 241-257 (2007).
[CrossRef]

Jeffries, J. B.

Kim, T.

L. A. Kranendonk, J. W. Walewski, T. Kim, and S. T. Sanders, "Wavelength-agile sensor applied for HCCI engine measurements," Proc. Combust. Inst. 30,1619-1627 (2005).
[CrossRef]

Kranendonk, L. A.

L. A. Kranendonk, A. W. Caswell, and S. T. Sanders, "Robust method for calculating temperature, pressure and absorber mole fraction from broadband spectra," Appl. Opt. 46, 4117-4124 (2007).
[CrossRef] [PubMed]

L. A. Kranendonk, R. Huber, J. G. Fujimoto, and S. T. Sanders, "Wavelength-agile H2O absorption spectrometer for thermometry of general combustion gases," Proc. Combust. Inst. 31, 783-790 (2007).
[CrossRef]

L. A. Kranendonk and S. T. Sanders, "Optical design in beam steering environments with emphasis on laser transmission measurements," Appl. Opt,  44, (2005) 6762-6772.
[CrossRef] [PubMed]

L. A. Kranendonk, J. W. Walewski, T. Kim, and S. T. Sanders, "Wavelength-agile sensor applied for HCCI engine measurements," Proc. Combust. Inst. 30,1619-1627 (2005).
[CrossRef]

Ma, L.

Mattison, D. W.

McNesby, K. L.

Najt, P. M.

R. E. Herold, D. E. Foster, J. B. Ghandhi, R. J. Iverson, J. A. Eng, and P. M. Najt, "Fuel unmixedness effects in a gasoline homogeneous charge compression ignition engine," Int. J. Engine Res. 8, 241-257 (2007).
[CrossRef]

Oehlschlaeger, M. A.

M. A. Oehlschlaeger, D. F. Davidson, and R. K. Hanson, "Investigation of the reaction of toluene with molecular oxygen in shock-heated gases," Combust. Flame 147, 195-208 (2006).
[CrossRef]

Sanders, S. T.

L. A. Kranendonk, R. Huber, J. G. Fujimoto, and S. T. Sanders, "Wavelength-agile H2O absorption spectrometer for thermometry of general combustion gases," Proc. Combust. Inst. 31, 783-790 (2007).
[CrossRef]

L. A. Kranendonk, A. W. Caswell, and S. T. Sanders, "Robust method for calculating temperature, pressure and absorber mole fraction from broadband spectra," Appl. Opt. 46, 4117-4124 (2007).
[CrossRef] [PubMed]

C. L. Hagen and S. T. Sanders, "Investigation of Multi-species (H2O2 and H2O) Sensing and Thermometry in an HCCI Engine by Wavelength-Agile Absorption Spectroscopy," Meas. Sci. Technol. 18, 1992-1998 (2006).
[CrossRef]

L. A. Kranendonk and S. T. Sanders, "Optical design in beam steering environments with emphasis on laser transmission measurements," Appl. Opt,  44, (2005) 6762-6772.
[CrossRef] [PubMed]

L. A. Kranendonk, J. W. Walewski, T. Kim, and S. T. Sanders, "Wavelength-agile sensor applied for HCCI engine measurements," Proc. Combust. Inst. 30,1619-1627 (2005).
[CrossRef]

S. T. Sanders, D. W. Mattison, L. Ma, J. B. Jeffries, and R. K. Hanson, "Wavelength-agile diode-laser sensing strategies for monitoring gas properties in optically harsh flows: application in cesium-seeded pulse detonation engine," Opt. Express,  10, (2002) 505-514.
[PubMed]

Taira, K.

Tennyson, J.

R. J. Barber, J. Tennyson, G. J. Harris, and R. N. Tolchenov, "A high-accuracy computed water line list," Monthly Notices of the Royal Astronomical Society 368, 1087-1094 (2006).
[CrossRef]

Tolchenov, R. N.

R. J. Barber, J. Tennyson, G. J. Harris, and R. N. Tolchenov, "A high-accuracy computed water line list," Monthly Notices of the Royal Astronomical Society 368, 1087-1094 (2006).
[CrossRef]

Walewski, J. W.

L. A. Kranendonk, J. W. Walewski, T. Kim, and S. T. Sanders, "Wavelength-agile sensor applied for HCCI engine measurements," Proc. Combust. Inst. 30,1619-1627 (2005).
[CrossRef]

Winkel, K. L.

Wojtkowski, M.

Appl. Opt

L. A. Kranendonk and S. T. Sanders, "Optical design in beam steering environments with emphasis on laser transmission measurements," Appl. Opt,  44, (2005) 6762-6772.
[CrossRef] [PubMed]

Appl. Opt.

Combust. Flame

M. A. Oehlschlaeger, D. F. Davidson, and R. K. Hanson, "Investigation of the reaction of toluene with molecular oxygen in shock-heated gases," Combust. Flame 147, 195-208 (2006).
[CrossRef]

Int. J. Engine Res.

R. E. Herold, D. E. Foster, J. B. Ghandhi, R. J. Iverson, J. A. Eng, and P. M. Najt, "Fuel unmixedness effects in a gasoline homogeneous charge compression ignition engine," Int. J. Engine Res. 8, 241-257 (2007).
[CrossRef]

Meas. Sci. Technol.

C. L. Hagen and S. T. Sanders, "Investigation of Multi-species (H2O2 and H2O) Sensing and Thermometry in an HCCI Engine by Wavelength-Agile Absorption Spectroscopy," Meas. Sci. Technol. 18, 1992-1998 (2006).
[CrossRef]

Monthly Notices of the Royal Astronomical Society

R. J. Barber, J. Tennyson, G. J. Harris, and R. N. Tolchenov, "A high-accuracy computed water line list," Monthly Notices of the Royal Astronomical Society 368, 1087-1094 (2006).
[CrossRef]

Opt. Express

Opt. Lett.

Proc. Combust. Inst.

L. A. Kranendonk, R. Huber, J. G. Fujimoto, and S. T. Sanders, "Wavelength-agile H2O absorption spectrometer for thermometry of general combustion gases," Proc. Combust. Inst. 31, 783-790 (2007).
[CrossRef]

L. A. Kranendonk, J. W. Walewski, T. Kim, and S. T. Sanders, "Wavelength-agile sensor applied for HCCI engine measurements," Proc. Combust. Inst. 30,1619-1627 (2005).
[CrossRef]

Other

A. W. Caswell, S. T. Sanders, and M. J. Chiaverini, "Swept-Wavelength Laser Absorption Tomography for Imaging Rocket Plume Gas Properties" in 41st AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit, "Swept-Wavelength Laser Absorption Tomography for Imaging Rocket Plume Gas Properties", (2005).

R. A. Palmer, J. L. Chao, R. M. Dittmar, V. G. Gregoriou, and S. E. Plunkett, "Investigation of Time-Dependent Phenomena by use of Step-Scan FT-IR" in Symposium on Advanced Infrared Spectroscopy (AIRS), "Investigation of Time-Dependent Phenomena by use of Step-Scan FT-IR," Tokyo, Japan, (1993) 1297-1310.

J. A. Filipa, J. W. Walewski, and S. T. Sanders, University of Wisconsin, 1500 Engineering Dr., Madison, WI 53706, are preparing a manuscript to be called "Optical beating in time-resolved spectroscopy. Part II: Strategies for spectroscopic sensing in the presence of optical beating".

J. W. Walewski, J. A. Filipa, and S. T. Sanders, University of Wisconsin, 1500 Engineering Dr., Madison, WI 53706, are preparing a manuscript to be called "Optical beating of polychromatic light and its impact ontime-resolved spectroscopy. Part I: Theory".

J. W. Goodman, "Some problems involving high-order coherence," in Statistical Optics (John Wiley & Sons, Inc., 1985), pp. 237-250.

M. J. Beran and Jr. G. Parrent, Theory of Partial Coherence, (Society of Photo-Optical Instrumentation Engineers, Palos Verdes Estates, 1974).

S. T. Sanders, "Online thermal beating noise calculator," http://chyp.erc.wisc.edu/tools/thermallight.html.

A. Suslov, B. K. Sarma, J. B. Ketterson, F. Balakirev, A. Migliori, and A. Lacerda, "Ultrasonic Instrumentation for Measurements in High Magnetic Fields. II. Pulsed Magnetic Fields" in 11th International Conference on Ion Sources, 2005, "Ultrasonic Instrumentation for Measurements in High Magnetic Fields. II. Pulsed Magnetic Fields" (AIP, Caen, France, 2006), pp. 35105-35111.

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Figures (9)

Fig. 1.
Fig. 1.

Schematic of FDML laser. A semiconductor optical amplifier (SOA) acts as gain medium, two isolators (ISO) ensure unidirectional lasing, a fiber Fabry Perot tunable filter (FFP-TF) which is driven by a sinusoidal electronic waveform provides active wavelength selection, a fiber coupler (FC) extracts light from the cavity, and a 2 km spool of single mode fiber (DELAY) optically stores the swept waveform and enables synchronization to the filter tuning period.

Fig. 2.
Fig. 2.

(One frame of 1.9 MB .avi movie) Individual intensity traces for the FDML laser used in this experiment at different FFP-TF drive frequencies, recorded at high temporal resolution (∼ 120 ps). At 120 ps time resolution, the relative beating noise is predicted to increase to 66% RMS [16]. At the lowest FFP-TF drive frequency, the FDML laser is detuned sufficiently that no mode-locking occurs; the high noise is attributed to beating. At slightly higher drive frequencies, patches of low noise appear. [Media 1]

Fig. 3.
Fig. 3.

Two cases of wavelength swept laser operation. (a) Drive frequency of FFP-filter in the FDML laser and optical roundtrip time slightly detuned. (b) Drive frequency and roundtrip time well matched.

Fig. 4.
Fig. 4.

Experimental configuration for reducing the minimum detectable absorbance in the presence of beating noise. Half of the light is directed through the engine, and half through a delay fiber. The light is recombined with a free-space beam splitter and the two signals are measured consecutively using a single photoreceiver.

Fig. 5.
Fig. 5.

Side (a) and isometric (b) views detailing the laser beam path through the combustion chamber. The laser beam is located 6.1 mm from the peak of the pent-roof and 7.7 mm from the fire deck, which for the present engine corresponds to the top of the piston at top dead center.

Fig. 6.
Fig. 6.

Upper panel: Absorbance (base e) spectrum measured at top dead center (TDC) of an engine motoring at 600 rpm (blue). A spectrum simulated from the BT2 database is shown as a reference (black); the conditions of the simulation are based on the best fit of the measured spectrum. Middle panel: Average of 28 sequential measured spectra (corresponding to 1 CAD) around TDC (red) with reference simulated spectrum (black). Lower panel: RMS difference between measured and simulated spectra (blue = no average, red = 28 average).

Fig. 7.
Fig. 7.

Temperature calculated from water absorption spectra as a function of crank angle, each point representing 10 μs of recorded data. This plot highlights the repeatable pattern attributed to trigger jitter.

Fig. 8.
Fig. 8.

Ideal gas temperature calculations (thick lines) and temperature calculated from absorption spectra (1 CAD average) versus crank angle degrees (CAD) from a motoring engine running at 600 rpm. The engine cycles had the intake air heated to 104 °C (blue), and 148 °C (red). Each measured point is calculated from H2O spectra averaged over 1 CAD. The measured temperatures for 3 consecutive engine cycles are shown in each case.

Fig. 9.
Fig. 9.

Ideal gas temperature calculations and temperature calculated from absorption spectra versus crank angle degrees (CAD) from a motoring engine running at 600 rpm (red) and 900 rpm (blue). Each measured point is calculated from H2O spectra averaged over 1 CAD. Again the measured data correspond to three consecutive engine cycles.

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