Abstract

We present the results of an experiment designed to verify the results of a previously published theoretical model that predicts the range resolution and peak-to-side lobe ratio of sparse frequency linearly frequency modulated (SF-LFM) ladar signals. We use two ultra stable diode lasers which are frequency locked and can be current tuned in order to adjust the difference frequency between the two lasers. The results of the experiment verify the previously developed model proving that SF-LFM ladar signals have the ability to increase the range resolution of a ladar system without the need for larger bandwidth modulators. Finally we simulate a target at a range of approximately 150 meters through the use of a fiber optic delay line, and demonstrate the ability of SF-LFM ladar signals to detect a target at range.

© 2010 OSA

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References

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  1. N. Levenon and E. Mozeson, Radar Signals, (Wiley-Interscience, 2004).
  2. C. J. Karlsson and F. Å. A. Olsson, “Linearization of the frequency sweep of a frequency-modulated continuous-wave semiconductor laser radar and the resulting ranging performance,” Appl. Opt. 38(15), 3376–3386 (1999), http://www.opticsinfobase.org/ao/abstract.cfm?URI=ao-38-15-3376 .
    [CrossRef]
  3. C. J. Karlsson, F. Å. A. Olsson, D. Letalick, and M. Harris, “All-Fiber Multifunction Continuous-Wave Coherent Laser Radar at 1.55 num for Range, Speed, Vibration, and Wind Measurements,” Appl. Opt. 39(21), 3716–3726 (2000), http://www.opticsinfobase.org/ao/abstract.cfm?URI=ao-39-21-3716 .
    [CrossRef]
  4. D. Nordin and K. Hyyppa, “Using a discrete thermal model to obtain a linear frequency ramping in a FMCW system,” Opt. Eng. 44(7), 74202–74205 (2005).
    [CrossRef]
  5. N. J. Miller, M. P. Dierking, and B. D. Duncan, “Optical sparse aperture imaging,” Appl. Opt. 46(23), 5933–5943 (2007), http://www.opticsinfobase.org/abstract.cfm?URI=ao-46-23-5933 .
    [CrossRef] [PubMed]
  6. R. L. Lucke, “Fundamentals of Wide-Field Sparse-Aperture Imaging,” in 2001 IEEE Aerospace Conference Proceedings (Institute of Electrical and Electronics Engineers, Big Sky,” Montana (March): 10–17 (2001).
  7. P. de Groot and J. McGarvey, “Chirped synthetic-wavelength interferometry,” Opt. Lett. 17(22), 1626–1628 (1992), http://www.opticsinfobase.org/abstract.cfm?URI=ol-17-22-1626 .
    [CrossRef] [PubMed]
  8. W. X. Liu, M. Lesturgie, and Y. L. Lu, “Real-time sparse frequency waveform design for HFSWR system,” Electron. Lett. 43(24), 1387–1389 (2007).
    [CrossRef]
  9. M. J. Lindenfeld, “Sparse Frequency Transmit and Receive Waveform Design,” IEEE Trans. Aerosp. Electron. Syst. 40(3), 851–861 (2004).
    [CrossRef]
  10. R. V. Chimenti, M. P. Dierking, P. E. Powers, and J. W. Haus, “Sparse frequency LFM ladar signals,” Opt. Express 17(10), 8302–8309 (2009), http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-17-10-8302 .
    [CrossRef] [PubMed]
  11. R. V. Chimenti, M. P. Dierking, P. E. Powers, and J. W. Haus, “Multiple chirp sparse frequency LFM ladar signals,” Proc. SPIE 7323, 73230N (2009).
    [CrossRef]
  12. R. V. Chimenti, E. S. Bailey, R. V. Dierking, M. P. Powers, P. E. Haus, and J. W. Haus, “A review of sparse frequency linearly frequency modulated (SF-LFM) laser radar signal modeling with preliminary experimental results,” 15th Coherent Laser Radar Conference (2009).
  13. R. V. Chimenti, “Sparse Frequency Linear Frequency Modulated Laser Radar Signal Generation, Detection, and Processing,” M. S. Thesis (University of Dayton, Dayton, OH, 2009).

2009 (2)

2007 (2)

N. J. Miller, M. P. Dierking, and B. D. Duncan, “Optical sparse aperture imaging,” Appl. Opt. 46(23), 5933–5943 (2007), http://www.opticsinfobase.org/abstract.cfm?URI=ao-46-23-5933 .
[CrossRef] [PubMed]

W. X. Liu, M. Lesturgie, and Y. L. Lu, “Real-time sparse frequency waveform design for HFSWR system,” Electron. Lett. 43(24), 1387–1389 (2007).
[CrossRef]

2005 (1)

D. Nordin and K. Hyyppa, “Using a discrete thermal model to obtain a linear frequency ramping in a FMCW system,” Opt. Eng. 44(7), 74202–74205 (2005).
[CrossRef]

2004 (1)

M. J. Lindenfeld, “Sparse Frequency Transmit and Receive Waveform Design,” IEEE Trans. Aerosp. Electron. Syst. 40(3), 851–861 (2004).
[CrossRef]

2001 (1)

R. L. Lucke, “Fundamentals of Wide-Field Sparse-Aperture Imaging,” in 2001 IEEE Aerospace Conference Proceedings (Institute of Electrical and Electronics Engineers, Big Sky,” Montana (March): 10–17 (2001).

2000 (1)

1999 (1)

1992 (1)

Chimenti, R. V.

de Groot, P.

Dierking, M. P.

Duncan, B. D.

Harris, M.

Haus, J. W.

Hyyppa, K.

D. Nordin and K. Hyyppa, “Using a discrete thermal model to obtain a linear frequency ramping in a FMCW system,” Opt. Eng. 44(7), 74202–74205 (2005).
[CrossRef]

Karlsson, C. J.

Lesturgie, M.

W. X. Liu, M. Lesturgie, and Y. L. Lu, “Real-time sparse frequency waveform design for HFSWR system,” Electron. Lett. 43(24), 1387–1389 (2007).
[CrossRef]

Letalick, D.

Lindenfeld, M. J.

M. J. Lindenfeld, “Sparse Frequency Transmit and Receive Waveform Design,” IEEE Trans. Aerosp. Electron. Syst. 40(3), 851–861 (2004).
[CrossRef]

Liu, W. X.

W. X. Liu, M. Lesturgie, and Y. L. Lu, “Real-time sparse frequency waveform design for HFSWR system,” Electron. Lett. 43(24), 1387–1389 (2007).
[CrossRef]

Lu, Y. L.

W. X. Liu, M. Lesturgie, and Y. L. Lu, “Real-time sparse frequency waveform design for HFSWR system,” Electron. Lett. 43(24), 1387–1389 (2007).
[CrossRef]

Lucke, R. L.

R. L. Lucke, “Fundamentals of Wide-Field Sparse-Aperture Imaging,” in 2001 IEEE Aerospace Conference Proceedings (Institute of Electrical and Electronics Engineers, Big Sky,” Montana (March): 10–17 (2001).

McGarvey, J.

Miller, N. J.

Nordin, D.

D. Nordin and K. Hyyppa, “Using a discrete thermal model to obtain a linear frequency ramping in a FMCW system,” Opt. Eng. 44(7), 74202–74205 (2005).
[CrossRef]

Olsson, F. Å. A.

Powers, P. E.

Appl. Opt. (3)

Electron. Lett. (1)

W. X. Liu, M. Lesturgie, and Y. L. Lu, “Real-time sparse frequency waveform design for HFSWR system,” Electron. Lett. 43(24), 1387–1389 (2007).
[CrossRef]

IEEE Trans. Aerosp. Electron. Syst. (1)

M. J. Lindenfeld, “Sparse Frequency Transmit and Receive Waveform Design,” IEEE Trans. Aerosp. Electron. Syst. 40(3), 851–861 (2004).
[CrossRef]

Montana (1)

R. L. Lucke, “Fundamentals of Wide-Field Sparse-Aperture Imaging,” in 2001 IEEE Aerospace Conference Proceedings (Institute of Electrical and Electronics Engineers, Big Sky,” Montana (March): 10–17 (2001).

Opt. Eng. (1)

D. Nordin and K. Hyyppa, “Using a discrete thermal model to obtain a linear frequency ramping in a FMCW system,” Opt. Eng. 44(7), 74202–74205 (2005).
[CrossRef]

Opt. Express (1)

Opt. Lett. (1)

Proc. SPIE (1)

R. V. Chimenti, M. P. Dierking, P. E. Powers, and J. W. Haus, “Multiple chirp sparse frequency LFM ladar signals,” Proc. SPIE 7323, 73230N (2009).
[CrossRef]

Other (3)

R. V. Chimenti, E. S. Bailey, R. V. Dierking, M. P. Powers, P. E. Haus, and J. W. Haus, “A review of sparse frequency linearly frequency modulated (SF-LFM) laser radar signal modeling with preliminary experimental results,” 15th Coherent Laser Radar Conference (2009).

R. V. Chimenti, “Sparse Frequency Linear Frequency Modulated Laser Radar Signal Generation, Detection, and Processing,” M. S. Thesis (University of Dayton, Dayton, OH, 2009).

N. Levenon and E. Mozeson, Radar Signals, (Wiley-Interscience, 2004).

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Figures (6)

Fig. 1
Fig. 1

A schematic of the experimental setup (no delay). The system components: splitter (Spl), Coupler (Cpl), photodiode (PD), the ultra stable laser diodes (USLD) and other components are discussed in the text.

Fig. 2
Fig. 2

The experimental data from Table 1 plotted on top of the modeled results for a 37MHz SF-LFM chirp ladar signal (a) PSLR verse difference frequency (b) range resolution verse difference frequency.

Fig. 3
Fig. 3

Comparison of experimental data and modeling with the waveform modified to fit the experimental chirp function for the range resolution (a) and PSLR (b) for a 4µs LFM chirp with a 37MHz bandwidth.

Fig. 4
Fig. 4

Zoomed in view of the data points from Fig. 4.3a showing the data follows the moving average of the theory and is within one standard deviation.

Fig. 5
Fig. 5

Schematic of the new experimental setup to test a time delay in the system. The signal was delayed by ~1µs. Refer to Fig. 1 for the component legend.

Fig. 6
Fig. 6

Matched filter output of a SF-LFM Signal with T = 4µs, B = 37 MHz, df = 50.1281 MHz, and τ ~1µs. (a) Full matched filter output. (b) Matched filter output zoomed in about τ/T = 0.25.

Tables (1)

Tables Icon

Table 1 Range resolution and PSLR for a SF-LFM ladar signal with a modulator bandwidth of 37MHz and a pulse duration of 4µs.

Equations (2)

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| χ ( τ , 0 ) | = I × I L O | sinc ( B τ ) e i 2 π ( f o + B 2 ) τ ( 1 + e i 2 π d f τ ) + B d f B [ δ ( τ + T d f B ) + δ ( τ T d f B ) ] e i 2 π 2 d f B ( d f + 2 f o ) τ { sinc ( ( B d f ) τ ) e i 2 π i ( f o + B + d f 2 ) τ ,      i f   d f B 0 ,      i f   d f > B | ,
δ R = δ τ × c 2 ,

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