Validating data analysis of broadband laser ranging

Fourier transform with matched non-linear frequency modulation in femtosecond laser ranging with imbalanced dispersion

We propose a new algorithm based on the Fourier transform with matched non-linear frequency modulation for processing femtosecond laser ranging data. The algorithm allows us to compensate for both the influence of the third-order dispersion in the fiber-based dispersive Fourier spectrometer and the influence of imbalanced second- and third-order dispersions in the interferometer. Computer simulations and experimental results show that the proposed algorithm significantly increases the accuracy of measuring the position of an object at larger displacements than the well-established non-linear time stretching.

In-fiber Michelson interferometric sensor fabricated by single CO2 laser pulse

An in-fiber Michelson interferometric sensor was presented by fabricating a concavity on the end face of a single mode fiber using a single CO₂ laser pulse. Reflected beams from the bottom and air-cladding boundary of the concavity are coupled into the fiber core and superimpose to generate a two-beam in-fiber Michelson interferometer. Compared with other laser-machining methods where multiple scanning cycles with precise manipulation are needed, the proposed method is more straightforward because only a single laser pulse is used to construct the sensor. The concavity constructed by the CO₂ laser is very smooth, and its shape could be controlled flexibly by changing the position of the single mode fiber and the parameters of the CO₂ laser pulse, so the fringe visibilities of the proposed sensors could be more than 15 dB, which is higher than that of the most reported laser-machining in-fiber Michelson interferometers. The proposed sensor was demonstrated by measuring the temperature with a sensitivity of 11.13 pm/°C. Furthermore, the proposed device is compact (<100 µm), economical, and robust. These advantages make it a promising candidate in practical applications.

The Short-Range, High-Accuracy Compact Pulsed Laser Ranging System

A short-range, compact, real-time pulsed laser rangefinder is constructed based on pulsed time-of-flight (ToF) method. In order to reduce timing discrimination error and achieve high ranging accuracy, gray-value distance correction and temperature correction are proposed, and are realized with a field programmable gate array (FPGA) in a real-time application. The ranging performances—such as the maximum ranging distance, the range standard deviation, and the ranging accuracy—are theoretically calculated and experimentally studied. By means of these proposed correction methods, the verification experimental results show that the achievable effective ranging distance can be up to 8.08 m with a ranging accuracy of less than ±11 mm. The improved performance shows that the designed laser rangefinder can satisfy on-line ranging applications with high precision, fast ranging speed, small size, and low implementation cost, and thus has potential in the areas of robotics, manufacturing, and autonomous navigation.