# Notes

Canonical: https://www.formlightoptics.com/notes
Markdown: https://www.formlightoptics.com/notes.md

Short technical notes. These are not case studies.

- [TIR collimator basics for LED downlights](https://www.formlightoptics.com/notes/tir-collimator-basics-for-led-downlights): How a PMMA collimator splits an LED into a refracted core and a reflected outer band, from a 2D ray trace.
- [Building a tolerance budget for a small imaging lens](https://www.formlightoptics.com/notes/tolerance-budget-for-a-small-imaging-lens): An example root-sum-square tolerance budget for a three-element imaging lens, with focus treated as a compensator.