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LiDAR (Light Detection And Ranging) systems measures the distance from the sensor to the target by determining the time between the release of the laser pulse to the receiving of the backscattered pulse. The interest in LiDAR technology has exploded in recent years since the applications are numerous. Here, we would highlight the Advanced Driver Assistance Systems (ADAS) and for rendezvous & docking operations between spacecraft. We built two LiDAR systems differing for the detector: a Silicon Photomultiplier (SiPM) and an Avalanche Photodiode (APD). The advantages of the SiPM approach has been extensively discussed in [1]. The comparison between these systems has been performed in terms of Time Of Flight (TOF) measurements varying the distance of the target at different intensities of ambient light and at various weather conditions. The APD, specifically designed for LiDAR applications, was chosen for its high performances at 905nm, the emission wavelength of our laser diode. The SiPM, fabricated by STMicroelectronics, was selected for its high responsivity, high gain, high fill factor with very low breakdown voltage (28V vs. 175V of the APD), low operating bias (30V vs. 164V of the APD) and low price. Both the LiDARs (Fig. 1) are battery-operated (supply voltage = 5V) and exhibit the same optical system with separated lenses for emission (2 glass lenses that behave as a collimator with an equivalent focal length of 110 mm) and receiving (a 100-mm focal length lens). The SiPM or the APD, that triggers the pulse stopping the time count, is placed behind the receiving lens. The laser diode is pulsed at 35ns with a pulse repetition frequency |
