h****a
发帖数: 234 | 1 a rough estimation:
radius = 1.22 lambda/D f
D=diameter of the beam |
b*****t
发帖数: 26 | 2 For ideal lens and a plane wave propagating along the optical axis
of the lens, the size equals to Ariy spot.
For stew line, need divide by sin(\theta) of Ariy spot.
For non-ideal lens, more complicated, please check the book for
optical engine. |
c*****t
发帖数: 1879 | 3
learning X-Ray Crystallography? :)
Informations can be obtained are:
1. crystal unit cell dimensions. They can be easily calculated using
Braggs' law. Usually you take the smallest distance between dots
(for primary lattice).
2. The intensities of the dots. The variations in intensities for these
dots are influenced by what are in the cell. A simple view is that
the intensities are the Amplitude of the waves w/o the phase.
The real space image determines the reciprocal space :) |
q*******u
发帖数: 68 | 4 你可以进入四方数据库系统下栽，www.yifan.org>科技>期刊， lucky! |
b*k
发帖数: 27 | 5 Assume L is regular, then from pumping lemma there is
a integer m > 0 such that for any enough long string w in L,
w can be decomposed into : w=xyz st. |xy| < m , |y| > 0 and
for any i>=0 xy^iz is also in L.
Consider w = a^nb^n in L, s.t n > m, then w can be decomposed into
w = xyz as stated in the pumping lemma, then take i = 0, from
the PL the string xz also in L. Since y contains only a so xz has
fewer a than b, it's a contradiction |
h*********n
发帖数: 3 | 6 It is not a simple question since you have to assume some
property of the grating, for instance, the refraction index
modulation. There are some methods to calculate it, like 4*4
transformation method. Or you can use 2*2 transformation
method or coupled wave method if you assume some condition. |
a****y
发帖数: 1035 | 7 if P(f=y)= L^y * e^(-L) / y! , (L=lamda)
then,
P(f/x =y)= L^(y*x)* e^(-L) / (y*x)!
P(ln(f/x) =y)= L^(e^y*x)* e^(-L) / (e^y*x)! |
