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How far will it actually reach? (and why we do not ship a calculator)

Every other supplier answers this with a number. The honest answer is a procedure: a range figure is a function of target size, target reflectance, visibility and the detection threshold — and the last one is not in any datasheet you will be shown.

Start here: which class of module do you need

Your target

Visibility you operate in

The published anchor points

Everything on this page is reasoned from measured points, quoted with their conditions. These are the only numbers in the catalogue that have a target and a visibility attached.

Module	Published range	Condition as published	Divergence
LRF1829C	23,000 m	6 x 6 m diffuse target, reflectance >= 30%, visibility >= 30 km	0.3 mrad
LRF1831C	12,000 m	20 x 20 m diffuse target, reflectance >= 30%, visibility >= 15 km	1.3 mrad
LRF0609C	6,000 m	vehicle-sized target, 0.3-reflectivity panel, visibility >= 12 km	0.5 mrad
LRF0405C	4,000 m	2 x 2 m class target, 30% reflectance, visibility >= 6 km	0.6 mrad

Why these four points cannot be turned into a calculator

The received power of a diffuse target follows

P ∝ ρ · min(A_target, A_beam(R)) · e^−2σR / R⁴

with σ ≈ k·3.912/V. Given one anchor point you can solve for the product of pulse energy, aperture, optics transmission and detector threshold — but not for each of them separately. That is enough to scale a small change, and not enough to cross a regime.

Concretely. Take the LRF1831C anchor: 12 km to a 20 × 20 m target at 30 % reflectance in 15 km visibility. Ask "what would it do against a 2.3 m target?" and the algebra returns about 4.9 km — if the link were atmosphere-limited in the same way at both distances, which it is not. At 12 km in 15 km visibility the atmosphere has already removed most of the budget, so the same module at 5 km is far above threshold. A naive scaling says 4.9 km; the truth could be 8 km. Both numbers are "modelled". Only one survives a bench test.

What to do instead

Read the condition, not the headline. 12 km at 20 × 20 m and 30 % reflectance is a different claim from 12 km at 0.3 m and 10 %.
Estimate the beam. Spot diameter ≈ divergence × distance. A 1.3 mrad module puts a 6.5 m spot at 5 km — anything smaller than that is a point target and costs you range fast.
Bench it. One afternoon, one target panel, twenty shots at three distances. The test guide has the procedure; it beats any calculator, including this page.
Ask us for the shortlist. We know which two modules to put on your bench, and we will say which one we expect to fail and why.

Give us four numbers, get two candidates Target size, reflectance, required distance, expected visibility. Email tommy@erdimail.com Error budget guide

Why publish a page that refuses to give a number

Because the alternative is a calculator that returns a confident number derived from one measurement and four assumptions. Buyers who have been burned once can tell the difference — and the ones who cannot were never going to survive a design review anyway.