Comb-calibrated frequency-modulated continuous-wave ladar for absolute distance measurements

Baumann, Esther; Giorgetta, Fabrizio R.; Coddington, Ian; Sinclair, Laura C.; Knabe, Kevin; Swann, William C.; Newbury, Nathan R.

doi:10.1364/ol.38.002026

Cited by 108 publications

(40 citation statements)

References 20 publications

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“…The advent of a new generation of mobile atomic clocks [16,17] and comb-based free-space optical frequency transfer [18] could permit precise timing networks, tests of relativity, and clock-based geodesy [19,20]. Finally, the precision and accuracy of comb-based LADARs are attractive for manufacturing and remote sensing in general [21][22][23][24][25][26][27][28][29][30]]. Here we demonstrate a self-referenced fiber frequency comb that can operate in the field while retaining its optical coherence and 5 femtosecond-level timing-jitter.…”

Section: Introductionmentioning

confidence: 99%

Operation of an optically coherent frequency comb outside the metrology lab

et al. 2014

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We demonstrate a self-referenced fiber frequency comb that can operate outside the wellcontrolled optical laboratory. The frequency comb has residual optical linewidths of < 1 Hz, subradian residual optical phase noise, and residual pulse-to-pulse timing jitter of 2.4 -5 fs, when locked to an optical reference. This fully phase-locked frequency comb has been successfully operated in a moving vehicle with 0.5 g peak accelerations and on a shaker table with a sustained 0.5 g rms integrated acceleration, while retaining its optical coherence and 5-fs-level timing jitter. This frequency comb should enable metrological measurements outside the laboratory with the precision and accuracy that are the hallmarks of comb-based systems.Work of the U.S.

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Section: Introductionmentioning

confidence: 99%

Operation of an optically coherent frequency comb outside the metrology lab

et al. 2014

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“…As the detected beat frequency is proportional to the desired range measurement through the speed of light and the chirp rate, the latter is the main parameter that must be calibrated to construct an accurate FMCW ladar system. Although characterization against an optical frequency comb showed that the sweep can be linearized and calibrated to less than 15 ppb [3,9,10], ∼ppm accuracy would be sufficient for most applications and a less-expensive traceable calibration method would be highly desired. Therefore, we focus in this paper on calibration by use of molecular frequency references HCN (C-band) or CO (L-band).…”

Section: Introductionmentioning

confidence: 99%

Precision and accuracy testing of FMCW ladar-based length metrology

Mateo

Barber

2015

Appl. Opt.

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The calibration and traceability of high-resolution frequency modulated continuous wave (FMCW) ladar sources is a requirement for their use in length and volume metrology. We report the calibration of FMCW ladar length measurement systems by use of spectroscopy of molecular frequency references HCN (C-band) or CO (L-band) to calibrate the chirp rate of the FMCW sources. Propagating the stated uncertainties from the molecular calibrations provided by NIST and measurement errors provide an estimated uncertainty of a few ppm for the FMCW system. As a test of this calibration, a displacement measurement interferometer with a laser wavelength close to that of our FMCW system was built to make comparisons of the relative precision and accuracy. The comparisons performed show <10 ppm agreement, which was within the combined estimated uncertainties of the FMCW system and interferometer.

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“…The sub-millimeter range resolution provided by the large bandwidth and the high sensitivity provided by coherent detection allows these FMCW ladar systems to make micron level precision range measurements at standoffs exceeding 10 m and to multiple simultaneous returns [3]. Calibration of these sources against molecular references [4] or optical frequency combs [5], [6] can provide ppm level or ppb level accuracy, respectively. Additionally, the multi-return capability of FMCW ladar allows measurement of multiple surfaces of (or through) transparent materials or obscurants.…”

Section: Introductionmentioning

confidence: 99%

Multi-dimensional, non-contact metrology using trilateration and high resolution FMCW ladar

Mateo

Barber

2015

Appl. Opt.

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Received Month X, XXXX; revised Month X, XXXX; accepted Month X, XXXX; posted Month X, XXXX (Doc. ID XXXXX); published Month X, XXXX Here we propose, describe, and provide experimental proof-of-concept demonstrations of a multi-dimensional, non-contact length metrology system design based on high resolution (millimeter to sub-100 micron) frequency modulated continuous wave (FMCW) ladar and trilateration based on length measurements from multiple, optical fiber-connected transmitters. With an accurate FMCW ladar source, the trilateration based design provides 3D resolution inherently independent of stand-off range and allows selfcalibration to provide flexible setup of a field system. A proof-of-concept experimental demonstration was performed using a highly-stabilized, 2 THz bandwidth chirped laser source, two emitters, and one scanning emitter/receiver providing 1D surface profiles (2D metrology) of diffuse targets. The measured coordinate precision of < 200 microns was determined to be limited by laser speckle issues caused by diffuse scattering of the targets.

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Comb-calibrated frequency-modulated continuous-wave ladar for absolute distance measurements

Cited by 108 publications

References 20 publications

Operation of an optically coherent frequency comb outside the metrology lab

Operation of an optically coherent frequency comb outside the metrology lab

Precision and accuracy testing of FMCW ladar-based length metrology

Multi-dimensional, non-contact metrology using trilateration and high resolution FMCW ladar

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