Three datasheets, three ranges: 23 km, 15 km, 8 km. All three call themselves "1535 nm laser rangefinder modules". None of those numbers can be compared, because none of them says what the laser was pointed at.
Here are three figures from our own catalogue, with the sentence that ships next to each one:
| Model | Published range | Condition, as published |
|---|---|---|
| LRF1829C | 23,000 m | line of sight, visibility not less than 26 km, humidity not greater than 50 % at 30 °C |
| LRF0610C | 6,000 m | ≥6,000 m against a 2.3 × 2.3 m reference target; ≥1,500 m against a human-size 0.5 × 1.7 m target |
| LRF0105C | 3,000 m | ≥3,000 m against 2.3 × 2.3 m at 30 % reflectance and ≥5 km visibility |
Look at the third row. Against the same reference target it claims 3 km; the 23 km row claims 23 km. Both are 1535 nm, both carry the same eye-safety argument, both talk over a serial link. What separates them is aperture, pulse energy, mass — and the condition each figure was measured under.
Why the condition is the only thing worth comparing first
At 1535 nm the transmitter is erbium glass and the receiver is InGaAs. Because the light is absorbed in the cornea before it reaches the retina, the allowable pulse energy is far higher than at 905 nm — which is exactly why 1535 nm modules exist at all in the kilometre range.
But "high pulse energy" does not mean "long range". Range depends on the target's reflectivity, its size, and how much daylight is in the receiver. A 23 km module against a 10 % reflective target in bad visibility is not a 23 km module. That is not a marketing problem, it is arithmetic.
Three questions resolve it faster than any datasheet:
- What target size and reflectance was the figure measured against?
- What visibility?
- Is the accuracy figure absolute (metres) or proportional (a percentage above some distance)?
What we did about it
We put the whole 1535 nm band on one page — every model, every published range, and the condition sitting next to it, unedited:
1535 nm laser rangefinder module — the band in one page
And the raw rows, if you would rather run your own filter:
- JSON / CSV: specs.erdilrf.com/data
- Versioned mirror: github.com/erdilrf-afk/erdi-lrf-specs
- Citable copy with a DOI: 10.5281/zenodo.23655337
If you have a datasheet in front of you that quotes a range with no condition, that is the first thing worth asking about — before the price, before the lead time.
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