From: boyd@apt0.sao.arizona.edu   
      
   Bret Cannon wrote:   
   >   
   >   
   > "alex"  wrote in message   
   > news:30ed2499-1d2f-4ede-b9b7-163e3a13b1e5@x8g2000yql.googlegroups.com...   
   >   
   > Just a quick check...  I am using an oriel Multispec (model 78854) and   
   > a fibre attached to the input.  The spectrum of the (already filtered   
   > light) has peaks of about 10nm.  It seems very wide, when I know that   
   > the peaks are much narrower, because the light has been filtered with   
   > a Fabry perot with a resolution of 1nm.   
   >   
   > So what is wrong?  Do I need to match the NA of the fibre to the focal   
   > length of the first mirror(concaved) to get better resolution.  Is   
   > something likely to be misaligned?   
   >   
   > When I move the fibre away from entrance slit a little the peaks   
   > narrow abit...   
   >   
   > I can find no manual or data about this model.  Although it seems to   
   > be a czerny turner spectrometer.   
   >   
   > Thanks   
   > Alex   
   > ALex   
   >   
   > What is the core diameter of the fiber?  Does the fiber diameter act as   
   > the entrance slit, so that the core diameter times the dispersion give a   
   > limit on the resolution?   
   >   
   > Bret Cannon   
      
   If the fiber is short length, significant light may propagate though the   
   cladding as well as the core further degrading the spectrometer's   
   resolution.   
      
   When you say the spectrometer has "peaks of about 10nm" are you   
   suggesting they have flat tops?  If so then you may be saturating the   
   detector.  If the input fiber isn't in the input focal plane of the   
   spectrometer it will also severely broaden the spectral lines.   
      
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