High Accuracy Distance Measurement by Two-Wavelength Pulsed Laser Source

摘要

The two-wavelength method permits fractional accuracies better than 1 ppm in ranging, and it has been so far applied only to continuous laser sources. An experiment was conducted to determine whether high power pulse lasers can be successfully used with this method, and to check the system feasibility. The main cause of error concerns threshold crossing in pulse discrimination specially in the presence of amplitude fluctuations. An analysis of error causes affecting such measurements was performed. Measurements on 5 and 13 km distances by pulsed ruby laser PTM emission (wavelength 6943 A) and its second harmonic (wavelength 3472 A) using a 20 psel accuracy time were made. Such measurements show that two-wavelength pulsed laser telemeters can reach 1 ppm accuracies for distances exceeding a few kilometers.