Choose a diffuser in the lit fixture, not from an unlit white sheet photo. LED spacing, distance to the cover, cavity surfaces and drive level all affect whether buyers see individual points, bright stripes or a smooth face. This worksheet helps you define a short two-sample trial and a PC diffuser quotation; the product page covers sheet options and sizes.
Request PC diffuser samples See PC diffuser sheet
First, check the geometry that causes hotspots
Less travel before the cover. Widely spaced LEDs are more likely to appear as points; a more scattering sheet may hide them but can reduce useful output.
More mixing distance may help evenness. Changing the gap can alter uniformity; test it alongside sheet options and record the geometry.
This is a concept diagram, not a photometric simulation. Record the real LED pitch (centre-to-centre spacing) and LED-to-cover gap in millimetres, plus the viewing angle. For example, “12 mm pitch, 8 mm gap” and “12 mm pitch, 20 mm gap” are two different fixture trials even with the same sheet; no universal pass/fail ratio is implied.
Choose the next sample from what you see
Swipe sideways to see all columns →
| Lit fixture symptom | Check before changing the sheet | Useful next trial |
|---|---|---|
| Distinct LED dots | Pitch, gap, viewing angle and whether each LED points at the cover. | Compare a more scattering PC diffuser at the same thickness and drive; measure output against the current cover. |
| Bright stripes or dark edges | LED layout, reflectors, cavity wall colour and edge shading. | Change one variable at a time; test the full lit cover, not only a small coupon. |
| Smooth appearance but too dim | Drive level, reference cover, optical losses and actual brightness target. | Test a more transmissive PC candidate while holding the hotspot acceptance limit. |
| Colour changes across a batch | LED colour bin, sheet thickness, coating, production reference and measuring method. | Agree a physical lit reference and written tolerance before production approval. |
A two-sample test a buyer can actually run
- Fix the setup: use the same LED array, drive setting, reflector, gap, viewing positions and camera exposure or meter method for both samples. Photograph the current cover as a baseline.
- Compare two PC candidates: one prioritizing hotspot hiding and one prioritizing light output, at the quoted thickness. Record both their grade/colour and the finished cover dimensions.
- Approve the lit result: judge visible points/stripes at your normal and angled viewing positions, output against your reference, colour and any dark-edge issue. If a numeric transmission/haze or luminance-uniformity target is required, name the test method and agree it before sampling.
Example acceptance wording you can adapt: “At our production LED drive and 18 mm LED-to-cover gap, no distinct LED points are visible from the normal 1 m viewing position or the specified side view. Measured output must meet our attached current-cover reference under the same setup.” The 18 mm and 1 m values are example buyer choices, not guaranteed values for any SinoPlastix grade. Add your own numerical brightness/uniformity limits if required by your design.
Copy this brief into your inquiry
Fill the lines below, then copy them into the message box on the request form. Missing measurements can be marked “to confirm”; a fixture photo and drawing are still useful.
The current opal PC diffuser route gives a starting thickness range of 2.0–8.0 mm; custom specifications can be reviewed. SinoPlastix can quote production-representative samples or finished cut covers. Common original test reports can be requested from sales; the lit assembly still needs buyer approval. The written custom quote confirms actual price and lead time; website averages are planning references.
Send the trial brief Ask about cut covers
Questions buyers ask
Can a diffuser sheet alone guarantee that LED dots disappear?
No. The same sheet can look different with another LED pitch, cover gap, drive or viewing angle. Test the candidate over the actual lit array and agree an acceptance view.
Should I choose the sheet with the highest haze?
Not automatically. More scattering can help hide points but may reduce useful light. Compare hotspot appearance and output together in your fixture, at the quoted grade and thickness.
What can I send before I know a transmission target?
Send LED pitch, cover gap, fixture photo, cover dimensions, quantity, desired appearance and current reference. We can suggest PC samples for an optical trial while you define any later numerical target.