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Hi all,

I've recently started working on an older 2-photon LSM (Prairie  
Ultima) using Hamamatsu R3896 PMTs. Compared to what I've seen on  
comparable systems in the past the images are very noisy. Given that  
the system has been used by many people over the years and was  
probably not always treated as well as it should, I have the suspicion  
that the PMTs might be degraded after having "seen" too much incident  
light.

 From my understanding, this should cause a loss in signal. Would it  
also explain the increase in noise?

If so, how would I go about verifying if this the case?

Thankful for any help,

Christian