Abstract

A first laboratory prototype of a novel concept for a short-range optical air data system for aircraft control and safety was built. The measurement methodology was introduced in [Appl. Opt. 51, 148 (2012)] and is based on techniques known from lidar detecting elastic and Raman backscatter from air. A wide range of flight-critical parameters, such as air temperature, molecular number density and pressure can be measured as well as data on atmospheric particles and humidity can be collected. In this paper, the experimental measurement performance achieved with the first laboratory prototype using 532 nm laser radiation of a pulse energy of 118 mJ is presented. Systematic measurement errors and statistical measurement uncertainties are quantified separately. The typical systematic temperature, density and pressure measurement errors obtained from the mean of 1000 averaged signal pulses are small amounting to < 0.22 K, < 0.36% and < 0.31%, respectively, for measurements at air pressures varying from 200 hPa to 950 hPa but constant air temperature of 298.95 K. The systematic measurement errors at air temperatures varying from 238 K to 308 K but constant air pressure of 946 hPa are even smaller and < 0.05 K, < 0.07% and < 0.06%, respectively. A focus is put on the system performance at different virtual flight altitudes as a function of the laser pulse energy. The virtual flight altitudes are precisely generated with a custom-made atmospheric simulation chamber system. In this context, minimum laser pulse energies and pulse numbers are experimentally determined, which are required using the measurement system, in order to meet measurement error demands for temperature and pressure specified in aviation standards. The aviation error margins limit the allowable temperature errors to 1.5 K for all measurement altitudes and the pressure errors to 0.1% for 0 m and 0.5% for 13000 m. With regard to 100-pulse-averaged temperature measurements, the pulse energy using 532 nm laser radiation has to be larger than 11 mJ (35 mJ), regarding 1-σ (3-σ) uncertainties at all measurement altitudes. For 100-pulse-averaged pressure measurements, the laser pulse energy has to be larger than 95 mJ (355 mJ), respectively. Based on these experimental results, the laser pulse energy requirements are extrapolated to the ultraviolet wavelength region as well, resulting in significantly lower pulse energy demand of 1.5 – 3 mJ (4–10 mJ) and 12–27 mJ (45–110 mJ) for 1-σ (3-σ) 100-pulse-averaged temperature and pressure measurements, respectively.

© 2013 OSA

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References

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  1. M. Fraczek, A. Behrendt, and N. Schmitt, “Laser-based air data system for aircraft control using Raman and elastic backscatter for the measurement of temperature, density, pressure, moisture, and particle backscatter coefficient,” Appl. Opt.51(2), 148–166 (2012).
    [CrossRef] [PubMed]
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  3. A. Behrendt, T. Nakamura, M. Onishi, R. Baumgart, and T. Tsuda, “Combined Raman lidar for the measurement of atmospheric temperature, water vapor, particle extinction coefficient, and particle backscatter coefficient,” Appl. Opt.41(36), 7657–7666 (2002).
    [CrossRef] [PubMed]
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    [CrossRef] [PubMed]
  5. A. Behrendt and J. Reichardt, “Atmospheric temperature profiling in the presence of clouds with a pure rotational Raman lidar by use of an interference-filter-based polychromator,” Appl. Opt.39(9), 1372–1378 (2000).
    [CrossRef] [PubMed]
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    [CrossRef]
  7. M. Radlach, A. Behrendt, and V. Wulfmeyer, “Scanning rotational Raman lidar at 355 nm for the measurement of tropospheric temperature fields,” Atmos. Chem. Phys.8(2), 159–169 (2008).
    [CrossRef]
  8. M. Radlach, “A scanning eye-safe rotational Raman lidar in the ultraviolet for measurements of tropospheric temperature fields,” PhD Dissertation (University of Hohenheim, Hohenheim, 2008).
  9. Y. F. Arshinov, S. M. Bobrovnikov, V. E. Zuev, and V. M. Mitev, “Atmospheric temperature measurements using a pure rotational Raman lidar,” Appl. Opt.22(19), 2984–2990 (1983).
    [CrossRef] [PubMed]
  10. G. J. Rabadan, N. P. Schmitt, T. Pistner, and W. Rehm, “Airborne lidar for automatic feedforward control of turbulent in-flight phenomena,” J. Aircr.47(2), 392–403 (2010).
    [CrossRef]
  11. N. P. Schmitt, W. Rehm, T. Pistner, H. Diehl, P. Navé, and G. J. Rabadan, “A340 flight test results of a direct detection onboard UV lidar in forward-looking turbulence measurement configuration,” in 15th Coherent Laser Radar Conference CLRC, 2009).
  12. Neslie Project,” retrieved March 2013, http://www.neslie-fp6.org .
  13. Daniela Project,” retrieved March 2013, http://www.danielaproject.eu .
  14. SAE International - The Engineering Society For Advancing Mobility Land Sea Air and Space, “Aerospace Standard AS8002: Air data computer - Minimum performance standard,” retrieved March 2013, www.sae.org .
  15. International Standard Atmosphere,” retrieved March 2013, http://www.icao.int .
  16. M. Fraczek, “Aircraft air data system based on the measurement of Raman and elastic backscatter via active optical remote-sensing,” PhD Thesis (University of Hohenheim, Hohenheim, Germany, 2013 - to be published).

2012 (1)

2010 (1)

G. J. Rabadan, N. P. Schmitt, T. Pistner, and W. Rehm, “Airborne lidar for automatic feedforward control of turbulent in-flight phenomena,” J. Aircr.47(2), 392–403 (2010).
[CrossRef]

2008 (1)

M. Radlach, A. Behrendt, and V. Wulfmeyer, “Scanning rotational Raman lidar at 355 nm for the measurement of tropospheric temperature fields,” Atmos. Chem. Phys.8(2), 159–169 (2008).
[CrossRef]

2004 (2)

P. Girolamo, R. Marchese, D. N. Whiteman, and B. Demoz, “Rotational Raman lidar measurements of atmospheric temperature in the UV,” Geophys. Res. Lett.31(1), L01106 (2004).
[CrossRef]

A. Behrendt, T. Nakamura, and T. Tsuda, “Combined temperature lidar for measurements in the troposphere, stratosphere, and mesosphere,” Appl. Opt.43(14), 2930–2939 (2004).
[CrossRef] [PubMed]

2002 (1)

2000 (1)

1983 (1)

Arshinov, Y. F.

Baumgart, R.

Behrendt, A.

Bobrovnikov, S. M.

Demoz, B.

P. Girolamo, R. Marchese, D. N. Whiteman, and B. Demoz, “Rotational Raman lidar measurements of atmospheric temperature in the UV,” Geophys. Res. Lett.31(1), L01106 (2004).
[CrossRef]

Diehl, H.

N. P. Schmitt, W. Rehm, T. Pistner, H. Diehl, P. Navé, and G. J. Rabadan, “A340 flight test results of a direct detection onboard UV lidar in forward-looking turbulence measurement configuration,” in 15th Coherent Laser Radar Conference CLRC, 2009).

Fraczek, M.

Girolamo, P.

P. Girolamo, R. Marchese, D. N. Whiteman, and B. Demoz, “Rotational Raman lidar measurements of atmospheric temperature in the UV,” Geophys. Res. Lett.31(1), L01106 (2004).
[CrossRef]

Marchese, R.

P. Girolamo, R. Marchese, D. N. Whiteman, and B. Demoz, “Rotational Raman lidar measurements of atmospheric temperature in the UV,” Geophys. Res. Lett.31(1), L01106 (2004).
[CrossRef]

Mitev, V. M.

Nakamura, T.

Navé, P.

N. P. Schmitt, W. Rehm, T. Pistner, H. Diehl, P. Navé, and G. J. Rabadan, “A340 flight test results of a direct detection onboard UV lidar in forward-looking turbulence measurement configuration,” in 15th Coherent Laser Radar Conference CLRC, 2009).

Onishi, M.

Pistner, T.

G. J. Rabadan, N. P. Schmitt, T. Pistner, and W. Rehm, “Airborne lidar for automatic feedforward control of turbulent in-flight phenomena,” J. Aircr.47(2), 392–403 (2010).
[CrossRef]

N. P. Schmitt, W. Rehm, T. Pistner, H. Diehl, P. Navé, and G. J. Rabadan, “A340 flight test results of a direct detection onboard UV lidar in forward-looking turbulence measurement configuration,” in 15th Coherent Laser Radar Conference CLRC, 2009).

Rabadan, G. J.

G. J. Rabadan, N. P. Schmitt, T. Pistner, and W. Rehm, “Airborne lidar for automatic feedforward control of turbulent in-flight phenomena,” J. Aircr.47(2), 392–403 (2010).
[CrossRef]

N. P. Schmitt, W. Rehm, T. Pistner, H. Diehl, P. Navé, and G. J. Rabadan, “A340 flight test results of a direct detection onboard UV lidar in forward-looking turbulence measurement configuration,” in 15th Coherent Laser Radar Conference CLRC, 2009).

Radlach, M.

M. Radlach, A. Behrendt, and V. Wulfmeyer, “Scanning rotational Raman lidar at 355 nm for the measurement of tropospheric temperature fields,” Atmos. Chem. Phys.8(2), 159–169 (2008).
[CrossRef]

Rehm, W.

G. J. Rabadan, N. P. Schmitt, T. Pistner, and W. Rehm, “Airborne lidar for automatic feedforward control of turbulent in-flight phenomena,” J. Aircr.47(2), 392–403 (2010).
[CrossRef]

N. P. Schmitt, W. Rehm, T. Pistner, H. Diehl, P. Navé, and G. J. Rabadan, “A340 flight test results of a direct detection onboard UV lidar in forward-looking turbulence measurement configuration,” in 15th Coherent Laser Radar Conference CLRC, 2009).

Reichardt, J.

Schmitt, N.

Schmitt, N. P.

G. J. Rabadan, N. P. Schmitt, T. Pistner, and W. Rehm, “Airborne lidar for automatic feedforward control of turbulent in-flight phenomena,” J. Aircr.47(2), 392–403 (2010).
[CrossRef]

N. P. Schmitt, W. Rehm, T. Pistner, H. Diehl, P. Navé, and G. J. Rabadan, “A340 flight test results of a direct detection onboard UV lidar in forward-looking turbulence measurement configuration,” in 15th Coherent Laser Radar Conference CLRC, 2009).

Tsuda, T.

Whiteman, D. N.

P. Girolamo, R. Marchese, D. N. Whiteman, and B. Demoz, “Rotational Raman lidar measurements of atmospheric temperature in the UV,” Geophys. Res. Lett.31(1), L01106 (2004).
[CrossRef]

Wulfmeyer, V.

M. Radlach, A. Behrendt, and V. Wulfmeyer, “Scanning rotational Raman lidar at 355 nm for the measurement of tropospheric temperature fields,” Atmos. Chem. Phys.8(2), 159–169 (2008).
[CrossRef]

Zuev, V. E.

Appl. Opt. (5)

Atmos. Chem. Phys. (1)

M. Radlach, A. Behrendt, and V. Wulfmeyer, “Scanning rotational Raman lidar at 355 nm for the measurement of tropospheric temperature fields,” Atmos. Chem. Phys.8(2), 159–169 (2008).
[CrossRef]

Geophys. Res. Lett. (1)

P. Girolamo, R. Marchese, D. N. Whiteman, and B. Demoz, “Rotational Raman lidar measurements of atmospheric temperature in the UV,” Geophys. Res. Lett.31(1), L01106 (2004).
[CrossRef]

J. Aircr. (1)

G. J. Rabadan, N. P. Schmitt, T. Pistner, and W. Rehm, “Airborne lidar for automatic feedforward control of turbulent in-flight phenomena,” J. Aircr.47(2), 392–403 (2010).
[CrossRef]

Other (8)

N. P. Schmitt, W. Rehm, T. Pistner, H. Diehl, P. Navé, and G. J. Rabadan, “A340 flight test results of a direct detection onboard UV lidar in forward-looking turbulence measurement configuration,” in 15th Coherent Laser Radar Conference CLRC, 2009).

Neslie Project,” retrieved March 2013, http://www.neslie-fp6.org .

Daniela Project,” retrieved March 2013, http://www.danielaproject.eu .

SAE International - The Engineering Society For Advancing Mobility Land Sea Air and Space, “Aerospace Standard AS8002: Air data computer - Minimum performance standard,” retrieved March 2013, www.sae.org .

International Standard Atmosphere,” retrieved March 2013, http://www.icao.int .

M. Fraczek, “Aircraft air data system based on the measurement of Raman and elastic backscatter via active optical remote-sensing,” PhD Thesis (University of Hohenheim, Hohenheim, Germany, 2013 - to be published).

M. Radlach, “A scanning eye-safe rotational Raman lidar in the ultraviolet for measurements of tropospheric temperature fields,” PhD Dissertation (University of Hohenheim, Hohenheim, 2008).

A. Behrendt, “Temperature measurements with lidar,” in Lidar: Range-Resolved Optical Remote Sensing of the Atmosphere, C. Weitkamp, ed. (Springer Series in Optical Sciences, 2005), pp. 273–305.

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Figures (6)

Fig. 1
Fig. 1

Calculated backscatter coefficients of the pure rotational Raman spectrum for a laser wavelength of 532.07 nm and air consisting of the relevant nitrogen and oxygen spectral lines. The coefficients are plotted for an air temperature of 295 K and air density present at sea level, together with the spectral transmission curves of the manufactured filters RR1 and RR2. The filter central wavelengths (CWLs) in this Fig. are 531.2 nm and 528.9 nm, respectively. The Raman radiation spectral data are taken from [2].

Fig. 2
Fig. 2

Concept of the laboratory emitter and receiver system. A pulsed laser emits light into the atmosphere. Four channels detect and spectrally filter the light backscattered from the measurement volume at distances between around 0.4 m and 0.83 m.

Fig. 3
Fig. 3

Typical signal pulses recorded with the APD detectors in channel RR1 and RR2 from air at a temperature of Tchamber = 238 K and a pressure of pchamber = 946 hPa. (a) Direct APD detector outputs. (b) Digitally filtered with a 50 MHz low-pass filter and normalized to the laser output pulse energy. The post-processed signal pulse peaks URR1 and URR2 relevant for the air data analysis are marked.

Fig. 4
Fig. 4

Results of the measurements performed with the atmospheric simulator. The plots illustrate the statistical measurement uncertainties ΔT (top), ΔN / N (center) and Δp / p (bottom) as a function of measurement altitude for different laser pulse energies at 532.07 nm (100% Α 118 mJ). The 1-σ uncertainties for 100-pulse-average detection are shown. For temperature and pressure measurements, the requirements set by the aviation standard AS8002 (sect. 1) are indicated by black lines. For density measurements, no requirements are specified in the aviation standard. The air temperatures and pressures adjusted inside the atmospheric simulator are specific for the shown altitudes according to the ISA model [15].

Fig. 5
Fig. 5

(a) Laser pulse energies EL,min necessary at 532 nm in order to meet the temperature measurement requirements with the measurement apparatus at different measurement altitudes specified for aviation in AS8002 (sect. 1 and Fig. 4). The solid lines show the values obtained with the uncertainty functions ΔXstat,T (1-σ and 3-σ) when averaging 100 subsequent pulses. Dashed lines indicate the upper (u.b.) and lower bounds (l.b.) for EL,min, when assuming the fit constants Δ0,T and Δ0,T being erroneous by 20%. (b) The same for air pressure measurements.

Fig. 6
Fig. 6

(a) Minimum laser pulse energies EL,min needed to meet the temperature measurement requirements for aviation (sect. 1 and Fig. 4) when using different laser wavelengths λL and analyzing the average of 100 signal pulses. The measurement altitude is 10300 m, which poses the highest demand for temperature measurements. The solid lines describe the values expected to be required with the current measurement apparatus (1-σ and 3-σ). Dashed lines mark the upper (u.b.) and lower bounds (l.b.) for EL,min, when assuming the fit constants Δ0,T and Δ0,T being erroneous by 20%. (b) The same for air pressure measurements. Here, the measurement altitude is 1500 m, which poses the highest demand for pressure measurements.

Tables (2)

Tables Icon

Table 1 Optical properties of the RR interference filters. The values put into brackets are the correspondent angles of incidence φ.

Tables Icon

Table 2 Overview of the laser pulse energies EL,min at different laser wavelengths being necessary to reach the measurement error requirements specified in sect. 1. The values of EL,min are listed for 10-pulse-average measurements and 100-pulse-average measurements with the current measurement system.

Equations (8)

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Q(T)= U RR2 ( T,N ) U RR1 ( T,N ) .
T calib = 2 c 1 c 2 + c 2 2 4 c 1 ( c 3 ln(Q) ) .
S(N)=( U RR1 ( T,N )+ c 1 U RR2 ( T,N ) ) ( 1+ c 2 Q( T )+ c 3 Q 2 ( T ) ) .
N calib =a S ,
Δ X stat = ΔX X = ( ΔA ) 2 + ( ΔB( E det ) ) 2 X .
Δ X stat,0 = ( Δ A 0 ) 2 + ( Δ B 0 ) 2 X 0 .
Δ X stat = ( Δ A 0 ) 2 + ( n E Δ B 0 ) 2 n E X 0 = ( 1 n E Δ A 0 ) 2 + ( 1 n E Δ B 0 ) 2 X 0 .
Δ X stat = ( E L,0 N chamber,0 E L N chamber Δ A 0 ) 2 + ( E L,0 N chamber,0 E L N chamber Δ B 0 ) 2 .

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