lens/helpers.lisp

   1 (in-package :lens)
   2
   3 ;;                      |
   4 ;; --------             |
   5 ;;   SS    \---         |
   6 ;;             \--      |
   7 ;;                X-----+-------------------------------
   8 ;;              /-  \   |
   9 ;;            /-     \  |
  10 ;;    nf=h  /-        \ | D/2=R
  11 ;;        /-           \|
  12 ;;      /-              |
  13 ;;    /- alpha          |
  14 ;; ---------------------+----------------------------------------
  15 ;;             nf       |
  16 ;;
  17 ;; sin(alpha) = R/nf
  18
  19 (defmethod back-focal-plane-radius ((objective objective))
  20   (declare (values double-float &optional))
  21   (with-slots (focal-length numerical-aperture) objective
  22     (* focal-length numerical-aperture)))
  23
  24 (defun focal-length-from-magnification (mag)
  25   (declare (double-float mag)
  26            (values double-float &optional))
  27   (/ 164.5 mag))
  28 #+nil
  29 (focal-length-from-magnification 63d0)
  30
  31 (defun make-objective (&key (magnification 63d0)
  32                        (numerical-aperture 1.38d0)
  33                        (immersion-index 1.515d0)
  34                        (center (v))
  35                        (normal (v 0 0 1)))
  36   (let* ((f (focal-length-from-magnification magnification))
  37          (o (make-instance 'objective
  38                            :bfp-radius 1d0 ;; these need to be generated
  39                            :focal-length f
  40                            :radius 1d0
  41                            :numerical-aperture numerical-aperture
  42                            :immersion-index immersion-index
  43                            :center center
  44                            :normal normal))
  45          (bfp-radius (back-focal-plane-radius o)))
  46     (make-instance 'objective
  47                    :bfp-radius bfp-radius
  48                    :focal-length f
  49                    :radius (* 10 bfp-radius)
  50                    :numerical-aperture numerical-aperture
  51                    :immersion-index immersion-index
  52                    :center center
  53                    :normal normal)))
  54 #+nil
  55 (make-objective)
  56
  57 (defmethod get-ray-behind-objective ((obj objective)
  58                                      x-mm y-mm bfp-x/r bfp-y/r)
  59   "Take a point on the back focal plane and a point in the sample and
  60  calculate the ray direction ro that leaves the objective. The return
  61  values are the exiting ray with normalized direction from the
  62  principal plane and the entering ray from the bfp."
  63   (declare (double-float x-mm y-mm)
  64            ((double-float -1d0 1d0) bfp-x/r bfp-y/r)
  65            (values ray ray &optional))
  66   (with-slots (bfp-radius center
  67                (f focal-length)) obj
  68     (let* ((theta (find-inverse-ray-angle obj x-mm y-mm))
  69            (phi (atan y-mm x-mm))
  70            (start (v+ center (make-vec (* bfp-radius bfp-x/r)
  71                                        (* bfp-radius bfp-y/r)
  72                                        (- f))))
  73            (enter (make-instance 'ray
  74                                  :start start
  75                                  :direction (v-spherical theta phi)))
  76            (exit (refract enter obj))
  77            (norm-exit (make-instance
  78                        'ray
  79                        :start (vector::start exit)
  80                        :direction (normalize (vector::direction exit)))))
  81       (values norm-exit enter))))
  82
  83 #+nil
  84 (get-ray-behind-objective .1d0 .1d0 0d0 0d0)