LiDAR brings with it a myriad of exciting applications, from autonomous vehicles, to mapping, to crop predictions and more. However, as the technology becomes more sophisticated, so does the demand for 300-meter range and increased laser power. Because of that, eye safety concerns and circuit tuning for ultrashort pulses to accommodate these concerns dominate design considerations.
It is key for manufacturers to design for short pulses and metricate them accurately. A circuit with multiple feedback loops can result in varying power pulse trains, which are not apparent when measuring average power.
In the March issue of Semiconductor Digest, the authors from Osram Opto Semiconductors present some ways to fine tune nanosecond drivers for multi-channel laser bars and properly metricate the laser pulse optically to ensure eye safety.
Although the circuit design and measurement setup will require some careful alignment and attention to detail, it is found to be worth the trouble. Accurate driver performance becomes obvious when one can observe changes in optical power over pulse trains, as well as true pulse shapes. The authors found this method of measurement provides the necessary feedback to correctly evaluate laser diode and driver performance and changes in spectral response with temperature simultaneously.