﻿Focal 
  Plane 
  of 
  a 
  Telescope 
  with 
  Circular 
  Aperture. 
  13 
  

  

  1 
  

  

  a. 
  

  

  J 
  R- 
  

  

  a. 
  

  

  J 
  E- 
  

  

  20 
  

  

  04695 
  

   0-4747 
  

   04832 
  

   0-4809 
  

   04830 
  

   0-4846 
  

   04860 
  

   0-4880 
  

   0-4895 
  

   0-4906 
  

   0-4915 
  

   0-4923 
  

   0-4946 
  

   0-4958 
  

  

  250 
  

  

  0-4985 
  

   0-4971 
  

   04977 
  

   0-4981 
  

   0-4984 
  

   0-4986 
  

   0-4988 
  

   0-4989 
  

   0-4990 
  

   0-4993 
  

   04995 
  

   0-4996 
  

   0-4996 
  

   0-5000 
  

  

  1 
  

  

  25 
  

  

  300 
  

  

  30 
  

  

  400 
  

  

  35 
  

  

  500 
  

  

  40 
  

  

  600 
  

  

  45 
  

  

  700 
  

  

  50 
  

  

  800 
  

  

  60 
  

  

  900 
  

  

  70 
  

  

  1000 
  

  

  80 
  

  

  1500 
  

  

  90 
  

  

  2000 
  

  

  100 
  

  

  2500 
  

  

  150 
  

  

  3000 
  

  

  00 
  

  

  200 
  

  

  

  

  6. 
  Intensity 
  at 
  any 
  Point 
  of 
  the 
  Focal 
  Plane 
  due 
  to 
  a 
  

   Circular 
  Source 
  of 
  Light. 
  

  

  Let 
  the 
  intensity 
  of 
  light 
  be 
  required 
  at 
  any 
  point 
  in 
  the 
  

   focal 
  plane 
  of 
  a 
  telescope, 
  where 
  the 
  point 
  O 
  may 
  lie 
  either 
  

   external 
  or 
  internal 
  to 
  the 
  image 
  of 
  the 
  circular 
  source 
  (see 
  

   figs. 
  3 
  and 
  4). 
  

  

  Fig. 
  3. 
  

  

  Fig. 
  4. 
  

  

  Put 
  zBCP 
  = 
  2</>; 
  ^BOP=0; 
  A0 
  = 
  S 
  ; 
  then 
  

  

  OP 
  2 
  = 
  / 
  D 
  2 
  =(a 
  + 
  S) 
  2 
  + 
  a 
  2 
  + 
  2a(a 
  + 
  S)cos2<^ 
  

   = 
  (2aTS) 
  2 
  -4a(rt 
  + 
  S) 
  sin 
  2 
  ; 
  

   when 
  lies 
  within 
  the 
  circle, 
  

  

  Pi 
  = 
  (2a-S) 
  •1-V«m^ 
  where 
  *?= 
  *?£~& 
  i 
  

  

  