Скриптуй @ подгоняй

def width(L, wlen, d):
    return L * wlen / d

wlen = 650 * 10 ** -9
d = map(lambda x : x * 10 ** -6, [71, 59, 35.33, 28.33])
L = map(lambda x : x * 10 ** -3, [320, 420, 520])

for di in d:
    print "d = %f" % di
    for l in L:
        print "L = %f, dx = %f" % (l, width(l, wlen, di))