See how time-of-flight know-how measures distance. Learn the way knowledge converters, optics, and sign processing are utilized in drones, LiDAR, and robotics.
Time-of-flight (ToF) optical strategies are utilized in varied purposes for exact distance measurement, together with laser security scanners, vary finders, drones, steerage programs, and autonomous autos. TIDA-01187, LIDAR-pulsed time-of-flight reference design utilizing high-speed knowledge converters from Texas Devices (TI), highlights the advantages of a high-speed knowledge converter-based resolution, reminiscent of improved goal identification, lowered pattern fee calls for, and an easier sign chain. It additionally covers optics, driver and receiver front-end circuits, ADCs, DACs, and sign processing.
Functions embody architectural surveying tools, automotive scanning LiDAR, drones, fuel evaluation, laser vary finders (LiDAR), laser security scanners, retinal imaging, and robotics.
The design helps a measurement vary of as much as 9 meters or extra with extra optics and elevated laser energy. It achieves a variety measurement imply error of lower than ±6 mm and a regular deviation of lower than 3 cm, guaranteeing excessive accuracy.
The system contains a 5.75-W pulsed 905-nm near-infrared laser diode and driver with a median output energy of lower than 1 mW. It features a near-infrared PIN photodiode with a high-speed trans-impedance amplifier entrance finish. Laser collimation and photograph receiver focusing optics are additionally included for enhanced efficiency.
Key elements embody 14-bit, 125-MSPS ADCs, 16-bit, 500-MSPS DACs, high-speed amplifiers, and exact clocking. The system makes use of a pulsed ToF measurement methodology with DFT-based vary estimation for improved effectivity. Moreover, automotive-grade variations can be found for chosen gadgets.
The coherent nature of laser mild makes it excellent for distance measurement, as it may be simply collimated right into a slender beam with minimal divergence. By using the fixed pace of sunshine, distance will be calculated by measuring the time it takes for laser mild to journey to a goal and return. Advances in small lasers and photodiodes have enabled the event of compact and moveable programs, supporting purposes reminiscent of laser security scanners, drones, laser vary finders, and steerage programs.
On this system, mild emitted by the laser is collimated right into a slender beam utilizing a lens. The beam travels to the goal, displays off it, and is then centered onto the detector by a second lens. The laser driver and stimulus subsystem can apply pulsed or amplitude modulation (AM) waveforms. Whereas some lasers assist frequency modulation (FM), which includes modulating the emitted wavelength, this function is past the scope of this design.
To additional optimize system vary, the optical detector—a PIN or avalanche photodiode—generates a present proportional to the return sign. A really low-noise TIA is crucial for amplifying the sign, as its amplitude decreases with the sq. of the space. The amplified sign is then processed to supply correct vary measurements, making this design a complete resolution for distance measurement purposes.
TI has examined this reference design. It comes with a invoice of supplies (BOM), schematics, meeting drawing, printed circuit board (PCB) format, and extra. The corporate’s web site has extra knowledge in regards to the reference design. To learn extra about this reference design, click on right here.
