Collar around the raft

Hi, please do not know anyone why the collar is made around the raft, resin black V4, year of manufacture 2021, resin tank LT.
I tried to move the Z-axis, no major difference, the printer is clean, everything aligned and tightened.
I don’t know what to do anymore, Firmware up to date (rc-1.19.23-965).
It doesn’t matter the size of the press or the type of raft, there is always a large collar around it, which sometimes loosens and completely degrades the entire contents of the tank with small fragments.
Thank you very much for your help.

Clean your optics - the glass cover and the mirrors inside. Follow the FL instructions carefully and only use the exact recommended materials (because the mirrors are very easy to damage).

You might also try lightly sanding the build platform. If it’s too reflective, I think this kind of problem can happen. In fact, try this first before you attempt to clean the optics.

Thanks for the answer,
the build platform is new, I bought another one for sure. The optical system is absolutely clean, the printer works in a dust-free environment.

However, during the last very large print, the printer got stuck, I checked to see if there was a dropped piece of print somewhere, but I didn’t find anything, so I continued printing and it ended up with a good result. This problem has been going on ever since.

Is it not possible for any damage or tilting of the tank holder? Thank you

The print itself looks pretty good, I think. It’s just the base that has the problem. The difference between the base and the print itself is the laser power level, which is higher for the base. But I can’t think of a good explanation for what you’re seeing, since my expectation would be that a problem as severe as this when the base is being printed should continue to have an affect on the rest of the print, too. It’s kind of weird that it’s doing what it’s doing. Maybe the resin is bad. It “overreacts” to the higher power level… that’s the next thing to try I guess - new resin.

I agree with @Randy_Cohen in that if I saw that print I’d suspect dirty optics and inspect the glass window, main mirror, galvos, etc. Even if your environment has no dust, I’ve noticed a thin hazy film tends to develop on the main mirror over time from printing.

thank you for the answers, I completely cleaned the upper glass and the main mirror. I’m sincerely afraid to touch the galvos so as not to damage them. And yes you were right, the main mirror had a lot of fine dust, I’d say it was greasy. I ordered a new resin and for a certain new tank and I’ll do another try. I hope this helps. Thank you and I will write what the result is.