10 REM RONCHI.BAS
20 REM
30 INPUT "Mirror diameter "
40 INPUT "Radius of curvature";R
50 INPUT "Grating frequency ";F
60 PRINT "Grating distance Delta"
70 PRINT " from the mirror's
80 PRINT " center of curvature"
90 INPUT " (+ is outside) ";DL
100 W=1/(2*F): REM Line width
120 CLS
130 SCREEN 2
140 X0=300: Y0=100: C=300
150 K=.42
160 CIRCLE (X0,Y0),C/2
170 FOR I=1 TO 10000
180 X=D*(RND(1)-.5)
190 Y=D*(RND(1)-.5)
200 REM X and Y are the ray's
210 REM coordinates on the face
220 REM of the mirror
230 S2=X*X+Y*Y
240 IF SQR(S2)>D/2 THEN 390
250 Z=R+S2/R
260 L=R+DL-Z
270 U=L*X/Z
280 REM Now, test to see if the
290 REM ray is blocked (FL=0)
300 REM or transmitted (FL=1)
310 REM by the grating
320 FL=0: REM Reset flag
330 T=INT(ABS(U/W)+.5)
340 IF T/2=INT(T/2) THEN FL=1
350 IF FL=0 THEN 390
360 XP=X0+X*C/D
370 YP=Y0+Y*K*C/D
380 PSET(XP,YP): REM Plot point
390 NEXT I
400 LOCATE 1,1
410 PRINT "Diameter = "
420 LOCATE 2,1
430 PRINT "R of C = ";R
440 LOCATE 3,1
450 PRINT "Ronchi freq =";F
460 LOCATE 4,1
470 PRINT "Delta = ";DL
480 END
490 REM ************************************
500 REM APPEARED IN ASTRONOMICAL COMPUTING
510 REM SKY & TELESCOPE - APRIL 1991 ISSUE
520 REM ************************************
