From: luweitest@address.invalid   
      
   On 2015-12-11 0:19, Phil Hobbs wrote:   
   > Could be defocusing caused by heating.  The hot spot becomes convex.   
   >   
   Unlikely, because the slit is set to 5nm, that is when measuring, only a   
   very small portion of spectra is passed onto the sample, and even if the   
   whole spectra is passed during aligning, the spot is not very bright or   
   hot to any extent that could curve the glass, for I can put my finger on   
   the focus.   
      
   --   
   Regards,   
   Lu Wei   
   PGP key ID: 0x92CCE1EA   
      
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