How to Choose a Linear LED Diffuser

Linear luminaires are judged along their whole length, so the diffuser has to be chosen as part of the optical design rather than picked from a catalogue at the end.

1. Start with the mounting method

The cross-section follows the housing. Snap-in and clip-on profiles fix into an aluminium extrusion; lay-in profiles rest on a frame; wrap-around and suspended profiles carry their own geometry. Decide this first, because it constrains everything else.

2. Set the transmission target

Efficacy targets push transmission up; appearance targets push it down. The useful exercise is to state the minimum acceptable luminaire efficacy, then choose the highest diffusion level that still meets it.

3. Check the LED pitch against the profile

Hotspots appear when the LEDs are too far apart for the diffusion and wall thickness. Diffusion level, wall thickness and LED pitch have to be considered together — which is why trial lengths in the real fixture are worth more than a calculation.

4. Choose the material

Polycarbonate for impact and temperature; PMMA for clarity, hardness and UV stability. Both are extruded in single-colour and two-colour forms.

5. Choose the surface finish

Frosted and embossed faces hide the LED pitch. Gloss faces keep output high but show the sources. Prismatic structures control glare and shape the distribution without sacrificing as much output as a diffusing surface.

6. Fix the length and the end preparation

Profiles are extruded continuously and cut to length, so the diffuser can match the luminaire dimension exactly. Specify end caps, mitring, notching or drilling at the same time.

Frequently asked questions

Can one profile serve a whole fixture family?

Often yes, if the housings share a mounting detail. Lengths are then cut per variant.

Do I need a prismatic or a frosted surface?

Prismatic if glare and distribution control matter; frosted if hiding the LED pitch matters most.