Broadband laser ranging (BLR) is essentially a spectral interferometer used to infer distance to a moving target. The light source is a mode-locked fiber laser, and chromatic dispersion maps the spectral interference pattern into the time domain, yielding chirped beat signals at the detector. A BLR record is a sequence of these chirped signals, representing consecutive target positions. To infer distance to a target, each underlying pulse envelope must be consistently registered and subtracted despite environmentally-induced variability. Then, nonlinear transformation of the phase is applied to remove the chirp, an FFT is performed to determine the peak frequency of the de-chirped signal, and a calibration factor relating de-chirped frequency to distance results in target position. Here, these analysis steps are discussed in detail.
Natalie Kostinski, Michelle A. Rhodes, Jared Catenacci, Marylesa Howard, Brandon M. La Lone, Patrick Younk, Adam Lodes, Corey V. Bennett, and Patrick J. Harding, "Broadband laser ranging: signal analysis and interpretation," Proc. SPIE 10089, Real-time Measurements, Rogue Phenomena, and Single-Shot Applications II, 100890G (Presented at SPIE LASE: January 30, 2017; Published: 22 February 2017); https://doi.org/10.1117/12.2255679.
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