On Friday, May 27, 2016 at 6:59:18 AM UTC-4, j.dem...@gmail.com wrote:   
   > Hi All   
   >    
   > I was hoping someone might be able to help me. I plan to build a simple   
   interferometer, for which I require some 90 degree hollow roof prism mirrors    
   (or alternative roof mirrors) with roughly +- 10 arcsec dihedral angle   
   accuracy. I have checked the    
   usual scientific suppliers (Thorlabs etc) but costs are more than $300 for a   
   one-inch-square component, which is unfortunately too much for this particular   
   project. Is anyone able to recommend a more economic option? Ideally, I am   
   looking for a cost of <    
   $100 per roof mirror. Are they by chance a standard component in any existing   
   mass-produced products?   
   >    
   > Many thanks!   
   >    
   > John   
      
   In the past I got some surplus optics from Anchor optics... but they got    
   bought by Edmunds and I think the prices went up.     
      
   Phil H. will mention the Surplus Shack.. or Shed.  I've never bought stuff   
   from them.   
      
   George H.   
      
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