Least-Square-Method-Based Optimal Laser Spots Acquisition and Position in Cooperative Target Measurement

Abstract

The relative positioning precisions of coordinate points is an important indicator that affects the final accuracy in the visual measurement system of space cooperative targets. Many factors, such as measurement methods, environmental conditions, data processing principles and equipment parameters, are supposed to influence the cooperative target’s acquisition and determine the precision of the cooperative target’s position in a ground simulation experiment with laser projected spots on parallel screens. To overcome the precision insufficiencies of cooperative target measurement, the factors of the laser diode supply current and charge couple device (CCD) camera exposure time are studied in this article. On the hypothesis of the optimal experimental conditions, the state equations under the image coordinates’ system that describe the laser spot position’s variation are established. The novel optimizing method is proposed by taking laser spot position as state variables, diode supply current and exposure time as controllable variables, calculating the optimal controllable variables through intersecting the focal spot centroid line and the 3-D surface, and avoiding the inconvenience of solving nonlinear equations. The experiment based on the new algorithm shows that the optimal solution can guarantee the focal spot’s variation range in 5–10 pixels under image coordinates’ system equivalent to the space with a 3 m distance and 0.6–1.2 mm positioning accuracy.

Research on Fiber-Optic Optical Coherence Ranging System Based on Laser Frequency Scanning Interferometry

“…FSI modulates the frequency or wavelength of lasers continuously, utilizing the change in the interference phase caused by demodulating frequency sweeps to achieve absolute distance measurement. Compared to femtosecond optical frequency comb methods, FSI devices are simpler and more cost-effective, playing important roles in scientific research and engineering applications such as alignment and measurement in high-energy particle detectors like the Large Hadron Collider [ 9 , 10 ], general coordinate measurements [ 11 , 12 ], and optical coherence tomography scans [ 13 , 14 ].…”