From: naftalline@gmail.com   
      
   On Wednesday, November 21, 2012 3:02:08 PM UTC-8, anorton wrote:   
   > "Naftalline"  wrote in message news:6f50   
   637-8341-4b4f-acfb-07f2e07d2c32@googlegroups.com... >Hi: > >The Polarizing   
   Beam Splitter Cubes we are using are N-BK7 and >12.7mmX12.7mmX12.7mm in size   
   and are from CVI. The operation    
   wavelength is >~ 900nm and its power is low (~ 50 >uW). >When we look into the   
   rejected PBS cubes (looking at the diagonal interface >where the polarization   
   coating is) we see the polarizing coating is not >uniform, part of it   
   appearing like an >   
   irregular stain (foggy looking), >this indicates that this polarization   
   coating might be going bad. We don't >what could cause this, our geuss is   
   humidity and temperature combination. > >Our requirements are the size   
   12.7mmX12.7mmX12.7mm, ~3 deg Field of    
   View, >and Extinction ratio > 500. > >We appreciate if you know of suplliers   
   that could provide these cubes, or >have ideas and suggestions > >thanks What   
   sort of humidity and temperture extremes are you dealing with? That really   
   should not be happening    
   for any sort of reasonable indoor environment outside of a steam bath. I am   
   thinking you might have simply received a defective batch. Irregular stains   
   could be due to bad cleaning of the surface before coating. I would contact   
   CVI. They might replace    
   them if the damage was not caused by abuse. As for other vendors, all the   
   major catalog houses -- Thorlabs, Edmund, Newport plus probably a few others   
   -- would likely have these. Search for NIR beamspitting cubes.   
      
      
      
   These PBS Cubes are inspected first before being used, there are no visible   
   irregular stains at this stage indicating any coating problem. These cubes are   
   inside of intstrument in an office environment, so temp and humidity is that   
   of an office area in    
   the local country.  We are sure the cubes are not from same batch, and this   
   problem occures from time to time.   
      
   We have sent poctures and data to CVI and they are looking into it.  I thought   
   it would be nice to know an alternative source, if this doesn't work out.   
      
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