Short answer: a module advertised as a 100 m laser rangefinder reaches 100 m only against a 90% reflective target. The ERDILRF LRF100H is specified 0.05–100 m at 90% reflectivity but 0.05–30 m at 10%. If you need a reliable 100 m against dark surfaces, the module you actually want is the LRF300H, rated 0.05–100 m at 10% reflectivity.
Why the 100 m on the box is only half a specification
Every ERDILRF H-series direct time-of-flight (DToF) module publishes two range figures, not one: a maximum range against a 90%-reflective target and a second, much shorter maximum against a 10%-reflective target. The headline number on a product listing is almost always the 90% figure, because it is the larger one. That figure is measured against a bright, diffuse, cooperative surface — a white calibration board, essentially.
Real surfaces are rarely that cooperative. Weathered concrete, dark grain in a silo, wet asphalt and dark vegetation all behave much closer to the 10% case. So the practical question is not which module says 100 m, but which module still returns a valid reading at 100 m against your worst surface. Those are two different modules in the ERDILRF catalogue. Our guide to rangefinder range and accuracy selection covers the physics; this article is about the buying decision that follows from it.
ERDILRF H-series modules around the 100 m class
| Specification | LRF50H | LRF100H | LRF200H | LRF300H |
|---|---|---|---|---|
| Range @ 90% reflectivity | 0.05–50 m | 0.05–100 m | 0.05–200 m | 0.05–300 m |
| Range @ 10% reflectivity | 0.05–15 m | 0.05–30 m | 0.05–70 m | 0.05–100 m |
| Accuracy | ±5 cm (<10 m) · 1% (≥10 m), 2σ | ±10 cm (<10 m) · 1% (≥10 m) | ±10 cm (<10 m) · 1% (≥10 m) | ±10 cm (<10 m) · 1% (≥10 m) |
| Measurement frequency | 20 Hz–10 kHz, default 1 kHz | 20 Hz–10 kHz, default 1 kHz | 20 Hz–10 kHz, default 1 kHz | 1 kHz or 50 Hz, auto-switched by echo strength |
| Interface | UART | UART / I²C | UART / I²C | UART / I²C |
| Supply voltage | 9–36 V DC | 9–36 V DC | 9–36 V DC | 9–36 V DC |
| Dimensions | 38 × 20 × 30 mm | 33 × 34 × 18 mm | 33 × 34 × 18 mm | 33 × 34 × 18 mm |
| Weight | 15 ± 2 g | 20 ± 2 g | 20 ± 2 g | 20 ± 2 g |
| Average power | 0.8 W | 0.7 W | 0.7 W | 1.2 W |
| Ambient light immunity | 45 m | 100 kLux | 100 kLux | 100 kLux |
| Published price | $160 USD / unit | $230 USD / unit | $250 USD / unit | $280 USD / unit |
All four run at 905 nm, are IEC 60825-1 Class 1, and share a 0.05 m minimum range, a beam divergence of roughly 4 mrad and an operating temperature range of −20 to +60 °C. The figures above are published prices; confirm current terms in writing before design-in, since volume pricing, lead time and Incoterms are quoted per enquiry.
Three rules for sizing a 100 m requirement
1. Decide which reflectivity column is your requirement. If your surface is a painted machine face, a light-coloured wall or a reflective plate, the 90% column is realistic and the LRF100H 100 m module is the direct fit. If your surface is dark, dusty, wet or oblique, read the 10% column instead — and in that column only the LRF300H 300 m module delivers 100 m.
2. Buy headroom, not the exact number. A module rated at exactly your working distance has no margin for a dirty window, an ageing laser diode, rain, or a surface that turned out darker than the sample you tested. The LRF200H 200 m module at 70 m / 10% is the sensible middle step when your worst case sits between 30 and 70 m.
3. Check the near end too. All four modules start at 0.05 m, so a 100 m module is not disqualified from short-distance work. That matters for level measurement in a tank or silo that runs from nearly full to nearly empty, where the sensor must stay valid across the whole span.
The differences that decide the design-in
Interface. This is the one that most often forces a change late in a project. The LRF50H is UART only. The LRF100H, LRF200H and LRF300H all offer UART or I²C. If your controller is short on UARTs and you were planning to hang the sensor off an existing I²C bus, the LRF50H 50 m module will not do it. On the UART side all four use the same B-family framing — 460800 baud, 8-N-1, a four-byte little-endian frame with a 5C header and a checksum byte — described in our serial protocol and checksum guide.
Aiming light. The LRF50H carries a switchable 650 nm visible red aiming light (Class 2) that automatically turns off below −20 °C. For an installer aligning a fixed mount on a crane rail or a silo roof, that visible red dot saves real commissioning time. The 100H, 200H and 300H do not list one, so plan an alignment jig or a sighting scope instead.
Update-rate behaviour. The LRF50H, LRF100H and LRF200H run 20 Hz to 10 kHz with a 1 kHz default. The LRF300H behaves differently: it runs at 1 kHz or 50 Hz and switches automatically according to reflected signal strength. That adaptive behaviour is what buys the extra reach, but it means your host firmware must tolerate a frame interval that changes at runtime rather than assuming a fixed 1 ms cadence.
Power budget. The LRF300H draws 1.2 W average against 0.7 W for the 100H and 200H. On a mains-powered industrial cabinet this is noise. On a solar-and-battery remote deformation monitor it may be the deciding constraint.
Typical civil applications in this range class
The listed civil applications for the LRF100H are wind power monitoring, landslide and deformation monitoring, and material level detection. The LRF200H is listed for port and bridge crane positioning, long conveyor protection and tunnel collision avoidance. The LRF300H adds UAV height and distance measurement, tower crane collision prevention and traffic early warning. If you are integrating one of these into a flight controller, the ArduPilot rangefinder documentation covers the driver and parameter side.
All modules referenced here are Class 1 under IEC 60825-1, meaning they are safe under all reasonably foreseeable conditions of use without protective eyewear — though the classification of your finished product is your own responsibility once the module sits behind your optics.
Frequently asked questions
Is the LRF100H a true 100 m laser rangefinder module?
Yes, at 90% target reflectivity. Its specified range is 0.05–100 m against a 90%-reflective surface and 0.05–30 m against a 10%-reflective one. Both numbers come from the same datasheet; which one applies depends entirely on what you are measuring against.
Which ERDILRF module gives 100 m against a dark surface?
The LRF300H. It is rated 0.05–300 m at 90% reflectivity and 0.05–100 m at 10% reflectivity, so 100 m sits inside its low-reflectivity specification rather than at the edge of its best-case one.
What accuracy can I expect at 100 m?
For the LRF100H, LRF200H and LRF300H the specification is ±10 cm below 10 m and 1% of distance at or above 10 m. At 100 m that 1% term works out to roughly ±1 m. The LRF50H is tighter at short range, ±5 cm below 10 m at 2σ.
Can I put a 100 m module on an I²C bus?
The LRF100H, LRF200H and LRF300H list UART and I²C. The LRF50H is UART only. Note that the I²C slave address is not stated in the H-series manuals, so request the register map from us before you commit to an I²C design.
Do these modules work outdoors in direct sun?
The LRF100H, LRF200H and LRF300H specify ambient light immunity of 100 kLux, which covers full daylight. The LRF50H publishes ambient light performance as a range in metres (45 m) rather than an illuminance threshold — a different metric, so compare it against your own conditions rather than converting between the two.
Tell us your worst-case surface
Send us your working distance, the surface you are measuring against and the interface your controller exposes, and we will confirm which module actually meets it — in writing, with the datasheet attached. Start at our contact page.