Changed Crystal and Diode filters in both the chiller room and in the PSL enclosure. 

   Crystal Chiller: Some darkening of the 0.5um filter in the enclosure. This darkening runs a bit more than half way up the filter, which means there was plenty of life left in this filter. There was a small amount of debris in the bottom of the filter. One was a small piece of metal,one small piece of what looked like some sealer material, and one bit of fuzz with a tail. This looked like plastic, perhaps from the installation. 

   The 1.0um Crystal chiller filter has some slight yellowing; but no debris of any size.   

   Diode Chiller: Both the 1.0um and the 0.5um filters showed no signs of any issues with this cooling circuit. Only a very slight yellowing of the 1.0um filter. NO debris in either filter.  

   After more than a year of continuous operations all four of these filters look great. The debris found the the 0.5um Crystal chiller filter is not significant. 

Closing WP #7337