%! 
(lenses.inc) run 

gsave 
72 72 scale 
0.01 setlinewidth 
2 2 translate 


newpath
0.5 -1 moveto 
4 -1 lineto 
4 4 lineto 
0.5 4 lineto 
closepath
clip 

newpath 
3 3 1 0 360 arc 
gsave 
0.8 0.9 1 setrgbcolor
fill 
grestore 
stroke 

1 0 0 setrgbcolor 
/x 3 def 
/y 1 25 div .0015 add def 
25 { 
newpath 
0 x moveto 
/P0 [0 x] def 
/V0 [1 0] def 
/C [3 3] def 
/R 1 def 

/P1 P0 V0 C R hit def 
P1 0 get P1 1 get lineto 


/n C P1 gradient normalized def 
/V1 n V0 1.33 refraction def 
/P2 P1 V1 C R hit def 
P2 0 get P2 1 get lineto 

/n C P2 gradient normalized def 
/V2 n V1 reflection def 
/P3 P2 V2 C R hit def 
P3 0 get P3 1 get lineto 

/n C P3 gradient normalized def 
/V3 n V2 1 1.33 div refraction def 
/P4 P3 V3 [1 0 0] line-intersection def 
P4 0 get P4 1 get lineto 

stroke 
/x x y add def 
} repeat 



newpath
0 0 0 setrgbcolor
/Times-Bold findfont
0.3 scalefont
setfont
42 rotate
1 -1 moveto
(Descartes Ray) show

grestore