Physics / mechanism
Time-of-Flight measures distance by timing light (or other EM radiation) round-trips. iToF (indirect) modulates a continuous-wave source and measures phase shift between emitted and received signals; depth = (c × Δφ) / (4πf). Typical precision: 1–5 mm at 1–4 m, 30–120 fps, 64×64 to 640×480 resolution. dToF (direct) fires discrete pulses and timestamps photon returns via SPAD (single-photon avalanche diode) arrays; resolves sub-mm at longer range, better outdoor performance. Key parameters: modulation frequency (iToF, 10–200 MHz), SPAD fill factor, TDC resolution (dToF, ~10–50 ps), multipath interference, and ambient light rejection. Apple’s LiDAR Scanner (iPhone/iPad) is mass-market dToF; Sony and STMicro dominate iToF sensor supply.
Competitive landscape
iToF competes directly with structured light (cheaper BOM, weaker outdoors), stereo vision (software-heavy, no active illumination cost), and scanning LiDAR (superior range/resolution, far higher cost). dToF competes with FMCW LiDAR (coherent detection, velocity + depth simultaneously, but complex PIC integration). Flash LiDAR is architecturally dToF at array scale.
Companies using
Connected ideas
Sources
Frontier (open questions)
- To be added.