Engineering note · 31 October 2026
905 nm vs 1535 nm laser rangefinder modules for drones
Choose the wavelength after you define the target, reflectance, visibility and payload envelope. The published distances below are not interchangeable headline numbers.
905 nm: compact UART rangefinding
The LRF3000A1 record specifies a 905 nm source, UART with 3.3 V TTL logic and a long-range test of at least 3,000 m against a building target at 70% reflectivity in clear weather with visibility of at least 4 km. That is a defined test case, not a guaranteed distance to every object seen from a drone.
1535 nm: longer-range conditions and a different receiver budget
The LRF0815C record specifies 1535 ± 5 nm and at least 8,000 m to a 2.3 m × 2.3 m target at 30% reflectance with visibility of at least 10 km. Its published ranging frequency is 0.5–10 Hz with up to three targets. The lower reflectance and longer visibility condition explain why this number must not be compared directly with the 905 nm building test.
What to measure before choosing
- Target: size, material, incidence angle and reflectance; vegetation and dark roofs are not the same as a white building.
- Flight envelope: vibration, motion, sunlight, fog and the update rate required by the flight controller.
- Integration: UART framing, supply voltage, mechanical envelope, thermal path and the mass budget of the payload.
- Acceptance test: repeat the supplier's target condition at the intended distance, then record false alarms and missed returns at the real mounting angle.
Practical selection
Use 905 nm modules when a compact UART path and a documented 0.2–3,000 m class test fit the payload. Use a 1535 nm module when the mission needs the longer published test case and can carry the corresponding optical, electrical and safety review. Send the target reflectance, dimensions, visibility and quantity in an RFQ; ERDI confirms the model-specific configuration, MOQ and lead time in writing.