lasertube falls apart

[waltfl]

Hi all
have you seen that a laser tube falls apart??
today during a job I realize that the power drop down and I look at the tube after checking all the mirrors and ther I see that the galss part in front of the tube was fallen off. I got no idea how this could happen because my cooling water is never mor then 70 degree
I dont even know what this part is for because it is open was just glued on to the front mirror of the laser tube.
it is very disapointing the whole shit
greetings
walt