Single-Photon Detection Laser Ranging Based On FP Etalon Filtering

Laser range finder is widely used because of its high measurement accuracy and large measurement range.Single photon detection laser ranging is one of the time-of-flight laser ranging technology,whose echo signal at single photon level can be detected by using single-photon detector.Moreover,its detection sensitivity can be increased to the quantum limit by using time-correlated single-photon counting method.Single photon detection laser ranging can not only greatly reduce laser power and improve the eye safety performance of laser range finder,but also can break through the current bottleneck of laser power and extend the measurement distance.Compared with the traditional laser ranging method based on linear optical detector,the single-photon detection laser ranging system is susceptible to background light.In the daytime with strong background,the single-photon detectors are easily saturated or even damaged.Therefore,all-day operation a key technical problem for the practical application of single-photon detection laser ranging.In this thesis,aiming at the technical difficulties of daytime single-photon detection laser ranging,a single photon detection laser ranging method based on FP etalon filtering is proposed.We used a narrow-band interference filter and an ultra-narrow linewidth FP etalon to form a second-order filter,and combined with spatial aperture filter to effectively suppress background light.At the same time,a piezoelectric ceramic deflector was used to drive the FP etalon,and adjust the central transmission wavelength of the FP etalon by adjusting the angle between incident light and the FP etalon,so that it can be locked with laser wavelength to keep high transmission of the echo light.In the experiment,we used the FP etalon to realize ultra-narrow band filter of 10 pm at 532 nm,and kept the laser echo at the maximum transmittance through photon-counting feedback control.The daytime laser ranging with a PMT single-photon detector was realized based on the filtering system.When the sunshine illumination was 1.1×10~4 lx,the background counts of the system was decreased 9.0×10~5counts per second.The ranging signal-to-noise ratio reached 16 dB,while the detection distance is 1.4km.The deflection adjustment method developed in this thesis can quickly lock the FP etalon on the laser wavelength,which provides an effective background light suppression method for all-day single-photon detection laser ranging.