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eyepiece

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eyepiece


  2  definitions  found 
 
  From  Webster's  Revised  Unabridged  Dictionary  (1913)  [web1913]: 
 
  Eyepiece  \Eye"piece`\,  n.  (Opt.) 
  The  lens,  or  combination  of  lenses,  at  the  eye  end  of  a 
  telescope  or  other  optical  instrument,  through  which  the 
  image  formed  by  the  mirror  or  object  glass  is  viewed. 
 
  {Collimating  eyepiece}.  See  under  {Collimate}. 
 
  {Negative},  or  {Huyghenian},  {eyepiece},  an  eyepiece 
  consisting  of  two  plano-convex  lenses  with  their  curved 
  surfaces  turned  toward  the  object  glass,  and  separated 
  from  each  other  by  about  half  the  sum  of  their  focal 
  distances,  the  image  viewed  by  the  eye  being  formed 
  between  the  two  lenses.  it  was  devised  by  Huyghens  who 
  applied  it  to  the  telescope.  Campani  applied  it  to  the 
  microscope,  whence  it  is  sometimes  called  {Campani's 
  eyepiece}. 
 
  {Positive  eyepiece},  an  eyepiece  consisting  of  two 
  plano-convex  lenses  placed  with  their  curved  surfaces 
  toward  each  other  and  separated  by  a  distance  somewhat 
  less  than  the  focal  distance  of  the  one  nearest  eye,  the 
  image  of  the  object  viewed  being  beyond  both  lenses;  -- 
  called  also  from  the  name  of  the  inventor,  {Ramsden's 
  eyepiece}. 
 
  {terrestrial},  or  {Erecting  eyepiece},  an  eyepiece  used  in 
  telescopes  for  viewing  terrestrial  objects,  consisting  of 
  three  or  usually  four  lenses,  so  arranged  as  to  present 
  the  image  of  the  object  viewed  in  an  erect  position. 
 
  From  WordNet  r  1.6  [wn]: 
 
  eyepiece 
  n  :  combination  of  lenses  at  the  viewing  end  of  optical 
  instruments  [syn:  {ocular}] 




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