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Message ID: 2976     Entry time: Mon May 24 16:34:22 2010
Author: Kevin 
Type: Update 
Category: PSL 
Subject: ND Filters for 2W Beam Profile 

I tried to measure the beam profile of the 2W laser today but ran into problems with the ND filters. With the measurements I made a few weeks ago, I used a reflective ND 4.0 filter on the PD. The PD started to saturate and Koji and I noticed that a lot of the metallic coating on the filter had been burnt off. Koji told me to use an absorptive ND 4.0 filter in front of a reflective ND 0.6 filter. I tried this today but noticed that a few holes were being burned into the absorptive filter and that the coating on the reflective filter behind it was also being burned off in spots. I don't think we wanted to use a polarizing beam splitter to reduce the power before the PD but I didn't want to ruin any more filters.

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