## Simultaneous ranging and velocimetry of fast moving targets using oppositely chirped pulses from a mode-locked laser |

Optics Express, Vol. 19, Issue 12, pp. 11213-11219 (2011)

http://dx.doi.org/10.1364/OE.19.011213

Acrobat PDF (1035 KB)

### Abstract

A lidar system based on the coherent detection of oppositely chirped pulses generated using a 20 MHz mode locked laser and chirped fiber Bragg gratings is presented. Sub millimeter resolution ranging is performed with > 25 dB signal to noise ratio. Simultaneous, range and Doppler velocity measurements are experimentally demonstrated using a target moving at > 330 km/h inside the laboratory.

© 2011 OSA

## 1. Introduction

5. B. W. Schilling, D. N. Barr, G. C. Templeton, L. J. Mizerka, and C. W. Trussell, “Multiple-return laser radar for three-dimensional imaging through obscurations,” Appl. Opt. **41**(15), 2791–2799 (2002). [CrossRef] [PubMed]

6. M.-C. Amann, T. Bosch, M. Lescure, R. Myllylä, and M. Rioux, “Laser ranging: a critical review of usual techniques for distance measurement,” Opt. Eng. **40**(1), 10 (2001). [CrossRef]

7. R. Agishev, B. Gross, F. Moshary, A. Gilerson, and S. Ahmed, “Range-resolved pulsed and CWFM lidars: potential capabilities comparison,” Appl. Phys. B **85**(1), 149–162 (2006). [CrossRef]

9. P. A. Hiskett, C. S. Parry, A. McCarthy, and G. S. Buller, “A photon-counting time-of-flight ranging technique developed for the avoidance of range ambiguity at gigahertz clock rates,” Opt. Express **16**(18), 13685–13698 (2008). [CrossRef] [PubMed]

10. J. Lee, Y.-J. Kim, K. Lee, S. Lee, and S. Kim, “Time-of-flight measurement with femtosecond light pulses,” Nat. Photonics **4**(10), 716–720 (2010). [CrossRef]

11. I. Coddington, W. C. Swann, L. Nenadovic, and N. R. Newbury, “Rapid and precise absolute distance measurements at long range,” Nat. Photonics **3**(6), 351–356 (2009). [CrossRef]

6. M.-C. Amann, T. Bosch, M. Lescure, R. Myllylä, and M. Rioux, “Laser ranging: a critical review of usual techniques for distance measurement,” Opt. Eng. **40**(1), 10 (2001). [CrossRef]

12. Z. W. Barber, W. R. Babbitt, B. Kaylor, R. R. Reibel, and P. A. Roos, “Accuracy of active chirp linearization for broadband frequency modulated continuous wave ladar,” Appl. Opt. **49**(2), 213–219 (2010). [CrossRef] [PubMed]

13. K. W. Holman, D. G. Kocher, and S. Kaushik, “MIT/LL development of broadband linear frequency chirp for high-resolution ladar,” Proc. SPIE **6572**, 65720J (2007). [CrossRef]

14. N. Satyan, A. Vasilyev, G. Rakuljic, V. Leyva, and A. Yariv, “Precise control of broadband frequency chirps using optoelectronic feedback,” Opt. Express **17**(18), 15991–15999 (2009). [CrossRef] [PubMed]

15. A. Vasilyev, N. Satyan, S. Xu, G. Rakuljic, and A. Yariv, “Multiple source frequency-modulated continuous-wave optical reflectometry: theory and experiment,” Appl. Opt. **49**(10), 1932–1937 (2010). [CrossRef] [PubMed]

16. P. A. Roos, R. R. Reibel, T. Berg, B. Kaylor, Z. W. Barber, and W. R. Babbitt, “Ultrabroadband optical chirp linearization for precision metrology applications,” Opt. Lett. **34**(23), 3692–3694 (2009). [CrossRef] [PubMed]

17. S. M. Beck, J. R. Buck, W. F. Buell, R. P. Dickinson, D. A. Kozlowski, N. J. Marechal, and T. J. Wright, “Synthetic-aperture imaging laser radar: laboratory demonstration and signal processing,” Appl. Opt. **44**(35), 7621–7629 (2005). [CrossRef] [PubMed]

18. C. J. Karlsson, F. A. A. Olsson, D. Letalick, and M. Harris, “All-fiber multifunction continuous-wave coherent laser radar at 1.55μm for range, speed, vibration, and wind measurements,” Appl. Opt. **39**(21), 3716–3726 (2000). [CrossRef]

21. R. E. Saperstein, N. Alic, S. Zamek, K. Ikeda, B. Slutsky, and Y. Fainman, “Processing advantages of linear chirped fiber Bragg gratings in the time domain realization of optical frequency-domain reflectometry,” Opt. Express **15**(23), 15464–15479 (2007). [CrossRef] [PubMed]

22. K. Kim, S. Lee, and P. J. Delfyett, “eXtreme chirped pulse amplification beyond the fundamental energy storage limit of semiconductor optical amplifiers,” IEEE J. Sel. Top. Quantum Electron. **12**(2), 245–254 (2006). [CrossRef]

23. S. Lee, D. Mandridis, and P. J. Delfyett Jr., “eXtreme chirped pulse oscillator operating in the nanosecond stretched pulse regime,” Opt. Express **16**(7), 4766–4773 (2008). [CrossRef] [PubMed]

24. M. U. Piracha, D. Nguyen, D. Mandridis, T. Yilmaz, I. Ozdur, S. Ozharar, and P. J. Delfyett, “Range resolved lidar for long distance ranging with sub-millimeter resolution,” Opt. Express **18**(7), 7184–7189 (2010). [CrossRef] [PubMed]

## 2. Temporally stretched, frequency chirped lidar for simultaneous velocity and range measurements

### 2.1 Interference of oppositely chirped pulses

_{up}in the up-chirped pulses, and another beat tone at frequency f

_{down}in the down-chirped pulses as shown in Fig. 1(b). The dispersion (D = 1651 ps/nm) of the CFBG can be expressed in terms of a chirp parameter S that is obtained by converting the dispersion units (from temporal delay per unit wavelength), to distance per unit optical frequency and then taking its inverse. This yields S = 250 MHz/mm, which implies a shift of 250 MHz in beat frequency for a 1 mm change in the target round trip distance. The one way target distance (d) is calculated by d = f

_{center}/ 2S where f

_{center}= (f

_{up}+ f

_{down}) / 2. The velocity is given by v = Δf . λ / 4 where Δf = f

_{down}– f

_{up}, and λ is the center wavelength. Since the observed frequency difference Δf is twice the actual Doppler shift in the echo signal, a factor of 2 has been included in the velocity calculation to account for this [2]. If f

_{down}> f

_{up}, the target is moving towards the observer, and vice versa.

### 2.2 Experimental setup for simultaneous, decoupled velocity and distance measurements

### 2.3 Results

_{center}= 1 GHz and Δf = 0.24 GHz as shown in Fig. 4(a) . This corresponds to a target distance of d = f

_{center}/ 2D = 2 mm from the mean position and a velocity of v = Δf . λ / 4 = 94 m/s. A signal to noise ratio of at least 25 dB is observed. A similar analysis of another segment from 39 – 40 µs reveals that the beat frequencies have shifted and a new value of f

_{center}= 2.28 GHz, corresponding to a new target distance of d = 4.56 mm (from the mean position) is observed. The width of each of the two notes is less than 140 MHz, resulting in a range resolution of < 0.3 mm. A beat note separation of Δf = 0.24 GHz is maintained, indicating a velocity of 94 m/s, which is in agreement with the previous velocity measurement. Separate Fourier transforms of the up and down-chirped pulses reveal f

_{down}> f

_{up}, indicating motion of the target away from the observer. The distance and velocity of the target at different times are given in Fig. 4(b). It must be noted that the beat notes in Fig. 4(a) are not single tones, but envelope structures over an array of narrow lines separated by 20 MHz (corresponding to the PRF of the MLL). For more accurate measurements, the ‘center of mass’ of the beat envelope can be determined or a MLL with a lower PRF can be used.

## 3. Discussion

_{up}and f

_{down}) do not look identical, as evident in Fig. 4(a). The setup can be modified as in [21

21. R. E. Saperstein, N. Alic, S. Zamek, K. Ikeda, B. Slutsky, and Y. Fainman, “Processing advantages of linear chirped fiber Bragg gratings in the time domain realization of optical frequency-domain reflectometry,” Opt. Express **15**(23), 15464–15479 (2007). [CrossRef] [PubMed]

25. J. A. Conway, G. A. Sefler, J. T. Chou, and G. C. Valley, “Phase ripple correction: theory and application,” Opt. Lett. **33**(10), 1108–1110 (2008). [CrossRef] [PubMed]

26. T.-J. Ahn, J. Y. Lee, and D. Y. Kim, “Suppression of nonlinear frequency sweep in an optical frequency-domain reflectometer by use of Hilbert transformation,” Appl. Opt. **44**(35), 7630–7634 (2005). [CrossRef] [PubMed]

## 4. Conclusion

## References and links

1. | T. Fujii, and T. Fukuchi, |

2. | M. I. Skolnik, |

3. | H. Araki, S. Tazawa, H. Noda, Y. Ishihara, S. Goossens, S. Sasaki, N. Kawano, I. Kamiya, H. Otake, J. Oberst, and C. Shum, “Lunar global shape and polar topography derived from Kaguya-LALT laser altimetry,” Science |

4. | “Lidar Tracks CO |

5. | B. W. Schilling, D. N. Barr, G. C. Templeton, L. J. Mizerka, and C. W. Trussell, “Multiple-return laser radar for three-dimensional imaging through obscurations,” Appl. Opt. |

6. | M.-C. Amann, T. Bosch, M. Lescure, R. Myllylä, and M. Rioux, “Laser ranging: a critical review of usual techniques for distance measurement,” Opt. Eng. |

7. | R. Agishev, B. Gross, F. Moshary, A. Gilerson, and S. Ahmed, “Range-resolved pulsed and CWFM lidars: potential capabilities comparison,” Appl. Phys. B |

8. | X. Sun, J. B. Abshire, M. A. Krainak, and W. B. Hasselbrack, “Photon counting pseudorandom noise code laser altimeters,” Proc. SPIE |

9. | P. A. Hiskett, C. S. Parry, A. McCarthy, and G. S. Buller, “A photon-counting time-of-flight ranging technique developed for the avoidance of range ambiguity at gigahertz clock rates,” Opt. Express |

10. | J. Lee, Y.-J. Kim, K. Lee, S. Lee, and S. Kim, “Time-of-flight measurement with femtosecond light pulses,” Nat. Photonics |

11. | I. Coddington, W. C. Swann, L. Nenadovic, and N. R. Newbury, “Rapid and precise absolute distance measurements at long range,” Nat. Photonics |

12. | Z. W. Barber, W. R. Babbitt, B. Kaylor, R. R. Reibel, and P. A. Roos, “Accuracy of active chirp linearization for broadband frequency modulated continuous wave ladar,” Appl. Opt. |

13. | K. W. Holman, D. G. Kocher, and S. Kaushik, “MIT/LL development of broadband linear frequency chirp for high-resolution ladar,” Proc. SPIE |

14. | N. Satyan, A. Vasilyev, G. Rakuljic, V. Leyva, and A. Yariv, “Precise control of broadband frequency chirps using optoelectronic feedback,” Opt. Express |

15. | A. Vasilyev, N. Satyan, S. Xu, G. Rakuljic, and A. Yariv, “Multiple source frequency-modulated continuous-wave optical reflectometry: theory and experiment,” Appl. Opt. |

16. | P. A. Roos, R. R. Reibel, T. Berg, B. Kaylor, Z. W. Barber, and W. R. Babbitt, “Ultrabroadband optical chirp linearization for precision metrology applications,” Opt. Lett. |

17. | S. M. Beck, J. R. Buck, W. F. Buell, R. P. Dickinson, D. A. Kozlowski, N. J. Marechal, and T. J. Wright, “Synthetic-aperture imaging laser radar: laboratory demonstration and signal processing,” Appl. Opt. |

18. | C. J. Karlsson, F. A. A. Olsson, D. Letalick, and M. Harris, “All-fiber multifunction continuous-wave coherent laser radar at 1.55μm for range, speed, vibration, and wind measurements,” Appl. Opt. |

19. | R. Schneider, P. Thurmel, and M. Stockmann, “Distance measurement of moving objects by frequency modulated laser radar,” Opt. Eng. |

20. | D. F. Pierrottet, F. Amzajerdian, L. Petway, B. Barnes, G. Lockard, and M. Rubio, “Linear FMCW laser radar for precision range and vector velocity measurements,” Proc. Mater. Res. Soc. Symp. (2008). |

21. | R. E. Saperstein, N. Alic, S. Zamek, K. Ikeda, B. Slutsky, and Y. Fainman, “Processing advantages of linear chirped fiber Bragg gratings in the time domain realization of optical frequency-domain reflectometry,” Opt. Express |

22. | K. Kim, S. Lee, and P. J. Delfyett, “eXtreme chirped pulse amplification beyond the fundamental energy storage limit of semiconductor optical amplifiers,” IEEE J. Sel. Top. Quantum Electron. |

23. | S. Lee, D. Mandridis, and P. J. Delfyett Jr., “eXtreme chirped pulse oscillator operating in the nanosecond stretched pulse regime,” Opt. Express |

24. | M. U. Piracha, D. Nguyen, D. Mandridis, T. Yilmaz, I. Ozdur, S. Ozharar, and P. J. Delfyett, “Range resolved lidar for long distance ranging with sub-millimeter resolution,” Opt. Express |

25. | J. A. Conway, G. A. Sefler, J. T. Chou, and G. C. Valley, “Phase ripple correction: theory and application,” Opt. Lett. |

26. | T.-J. Ahn, J. Y. Lee, and D. Y. Kim, “Suppression of nonlinear frequency sweep in an optical frequency-domain reflectometer by use of Hilbert transformation,” Appl. Opt. |

**OCIS Codes**

(120.0120) Instrumentation, measurement, and metrology : Instrumentation, measurement, and metrology

(280.0280) Remote sensing and sensors : Remote sensing and sensors

(280.3340) Remote sensing and sensors : Laser Doppler velocimetry

(280.3640) Remote sensing and sensors : Lidar

**ToC Category:**

Remote Sensing and Sensors

**History**

Original Manuscript: March 14, 2011

Revised Manuscript: May 17, 2011

Manuscript Accepted: May 19, 2011

Published: May 24, 2011

**Citation**

Mohammad U. Piracha, Dat Nguyen, Ibrahim Ozdur, and Peter J Delfyett, "Simultaneous ranging and velocimetry of fast moving targets using oppositely chirped pulses from a mode-locked laser," Opt. Express **19**, 11213-11219 (2011)

http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-19-12-11213

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### References

- T. Fujii, and T. Fukuchi, Laser Remote Sensing (Taylor & Francis, 2005).
- M. I. Skolnik, Introduction to Radar Systems (McGraw-Hill, 2001).
- H. Araki, S. Tazawa, H. Noda, Y. Ishihara, S. Goossens, S. Sasaki, N. Kawano, I. Kamiya, H. Otake, J. Oberst, and C. Shum, “Lunar global shape and polar topography derived from Kaguya-LALT laser altimetry,” Science 323(5916), 897–900 (2009). [CrossRef] [PubMed]
- “Lidar Tracks CO2,” Gary Gimmestad, SPIE Professional January, 2011.
- B. W. Schilling, D. N. Barr, G. C. Templeton, L. J. Mizerka, and C. W. Trussell, “Multiple-return laser radar for three-dimensional imaging through obscurations,” Appl. Opt. 41(15), 2791–2799 (2002). [CrossRef] [PubMed]
- M.-C. Amann, T. Bosch, M. Lescure, R. Myllylä, and M. Rioux, “Laser ranging: a critical review of usual techniques for distance measurement,” Opt. Eng. 40(1), 10 (2001). [CrossRef]
- R. Agishev, B. Gross, F. Moshary, A. Gilerson, and S. Ahmed, “Range-resolved pulsed and CWFM lidars: potential capabilities comparison,” Appl. Phys. B 85(1), 149–162 (2006). [CrossRef]
- X. Sun, J. B. Abshire, M. A. Krainak, and W. B. Hasselbrack, “Photon counting pseudorandom noise code laser altimeters,” Proc. SPIE 6771, 677100 (2007).
- P. A. Hiskett, C. S. Parry, A. McCarthy, and G. S. Buller, “A photon-counting time-of-flight ranging technique developed for the avoidance of range ambiguity at gigahertz clock rates,” Opt. Express 16(18), 13685–13698 (2008). [CrossRef] [PubMed]
- J. Lee, Y.-J. Kim, K. Lee, S. Lee, and S. Kim, “Time-of-flight measurement with femtosecond light pulses,” Nat. Photonics 4(10), 716–720 (2010). [CrossRef]
- I. Coddington, W. C. Swann, L. Nenadovic, and N. R. Newbury, “Rapid and precise absolute distance measurements at long range,” Nat. Photonics 3(6), 351–356 (2009). [CrossRef]
- Z. W. Barber, W. R. Babbitt, B. Kaylor, R. R. Reibel, and P. A. Roos, “Accuracy of active chirp linearization for broadband frequency modulated continuous wave ladar,” Appl. Opt. 49(2), 213–219 (2010). [CrossRef] [PubMed]
- K. W. Holman, D. G. Kocher, and S. Kaushik, “MIT/LL development of broadband linear frequency chirp for high-resolution ladar,” Proc. SPIE 6572, 65720J (2007). [CrossRef]
- N. Satyan, A. Vasilyev, G. Rakuljic, V. Leyva, and A. Yariv, “Precise control of broadband frequency chirps using optoelectronic feedback,” Opt. Express 17(18), 15991–15999 (2009). [CrossRef] [PubMed]
- A. Vasilyev, N. Satyan, S. Xu, G. Rakuljic, and A. Yariv, “Multiple source frequency-modulated continuous-wave optical reflectometry: theory and experiment,” Appl. Opt. 49(10), 1932–1937 (2010). [CrossRef] [PubMed]
- P. A. Roos, R. R. Reibel, T. Berg, B. Kaylor, Z. W. Barber, and W. R. Babbitt, “Ultrabroadband optical chirp linearization for precision metrology applications,” Opt. Lett. 34(23), 3692–3694 (2009). [CrossRef] [PubMed]
- S. M. Beck, J. R. Buck, W. F. Buell, R. P. Dickinson, D. A. Kozlowski, N. J. Marechal, and T. J. Wright, “Synthetic-aperture imaging laser radar: laboratory demonstration and signal processing,” Appl. Opt. 44(35), 7621–7629 (2005). [CrossRef] [PubMed]
- C. J. Karlsson, F. A. A. Olsson, D. Letalick, and M. Harris, “All-fiber multifunction continuous-wave coherent laser radar at 1.55μm for range, speed, vibration, and wind measurements,” Appl. Opt. 39(21), 3716–3726 (2000). [CrossRef]
- R. Schneider, P. Thurmel, and M. Stockmann, “Distance measurement of moving objects by frequency modulated laser radar,” Opt. Eng. 40(1), 33–37 (2001). [CrossRef]
- D. F. Pierrottet, F. Amzajerdian, L. Petway, B. Barnes, G. Lockard, and M. Rubio, “Linear FMCW laser radar for precision range and vector velocity measurements,” Proc. Mater. Res. Soc. Symp. (2008).
- R. E. Saperstein, N. Alic, S. Zamek, K. Ikeda, B. Slutsky, and Y. Fainman, “Processing advantages of linear chirped fiber Bragg gratings in the time domain realization of optical frequency-domain reflectometry,” Opt. Express 15(23), 15464–15479 (2007). [CrossRef] [PubMed]
- K. Kim, S. Lee, and P. J. Delfyett, “eXtreme chirped pulse amplification beyond the fundamental energy storage limit of semiconductor optical amplifiers,” IEEE J. Sel. Top. Quantum Electron. 12(2), 245–254 (2006). [CrossRef]
- S. Lee, D. Mandridis, and P. J. Delfyett., “eXtreme chirped pulse oscillator operating in the nanosecond stretched pulse regime,” Opt. Express 16(7), 4766–4773 (2008). [CrossRef] [PubMed]
- M. U. Piracha, D. Nguyen, D. Mandridis, T. Yilmaz, I. Ozdur, S. Ozharar, and P. J. Delfyett, “Range resolved lidar for long distance ranging with sub-millimeter resolution,” Opt. Express 18(7), 7184–7189 (2010). [CrossRef] [PubMed]
- J. A. Conway, G. A. Sefler, J. T. Chou, and G. C. Valley, “Phase ripple correction: theory and application,” Opt. Lett. 33(10), 1108–1110 (2008). [CrossRef] [PubMed]
- T.-J. Ahn, J. Y. Lee, and D. Y. Kim, “Suppression of nonlinear frequency sweep in an optical frequency-domain reflectometer by use of Hilbert transformation,” Appl. Opt. 44(35), 7630–7634 (2005). [CrossRef] [PubMed]

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