Cracked polarizing lens?

Hi all-

replaced my laser tube on my 40*60" setup. Next thing I notice, the polarizing filter (I think that’s what it is, the first “lens”) is cracked.

Anyone know what this is called and where to buy a replacement?
Anyone know why it would crack??


I looked at the user manual for this and did not see anything except mirrors. I’ve never seen a polarizing lens on one of these… Can you show us where it came from?

It’s not in the manual…