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Optics test got worse after cleaning


I ran an optics test and the results were not bad but there could be some improvement. I cleaned the glass top and bottom and cleaned the mirror. After reassembling and running a new test the results were dramatically worse. Below is before (good) and after (bad). Any help would be greatly appreciated.


How, exactly, did you clean the mirror?


I used IPA on a swab


You may have ruined your mirrors.

The mirrors in the FL printers are all “primary” mirrors. This means the reflective coating (a very thin layer of aluminum applied by vapor deposition) is on the front side of the glass. So if you just wipe down the mirror like you would the mirror in your bathroom, you’ll probably remove some or most of the reflective coating, and or abrade the surface so it’s specularity increases and it scatters the laser light (the effect would be like the laser was defocused), or both.


FL strongly recommends that you clean the mirrors with “Pec Pads”, which are specifically designed so they will minimize any abrasion of the aluminum reflective coating when you clean them.

You probably need to open a support ticket with FL now, and see if they can help you figure out if the mirrors are toast or there is some other problem.


I got the same issue.
I got this result before cleaning, and after. I think that something is wrong with the laser because mirrors are in very good condition.


The lasers definitely do wear out.

But using a generic cotton swab on the mirrors is not a good idea.


But instructions for cleaning from FL saying that you must use a cotton swab.


Just following up. I took apart the printer and thoroughly cleaned the optics, mirror and glass with PEC PADS and IPA. Below are pictures of the results with the optics file. The results are vastly better than my original print. I also adjusted the z and after adjustment the 4 blocks measure 12.00mm-12.03mm in height which I think is adequate. It looks like I am good to go. Thanks for following up.


Every place I’ve looked, the FL instructions for cleaning say to use “PEC*PAD contaminant free wipes” on both the mirrors and the glass window.



Hi @E3DP,

I’m glad that you were able to resolve this issue! For reference, Formlabs recommends “PEC*PAD contaminant-free wipes” and “90% or higher isopropyl alcohol, non-recycled” to clean the optical surfaces of the printer. Any other materials could damage the optical surfaces and affect print quality on your machine. For more information, be sure to check out our official support article!