COMBINED DISPLACEMENT
If there are several anisoplanatic effects present, with each not
decreasing the Strehl ratio much, it is a common practice to
multiply the Strehl ratios for the individual effects to get a
combined Strehl ratio. The validity of this assumption is now
examined. The total displacement that is due to a translation, an
angular offset, a time delay, and a chromatic offset is
#math104#
| dt(z) = d + #tex2html_wrap_indisplay1258#θz + v(z)τ + dc(z), |
|
|
(46) |
where chromatic displacement is given in Eq. (50).
The two terms necessary for calculating the Strehl ratio are
#math105#
| E |
= |
#tex2html_wrap_indisplay1265#, |
(47) |
| σ#tex2html_wrap_indisplay1267#2 |
= |
d 5/3, |
(48) |
where
#math106#
| dm = 2.91 k02#tex2html_wrap_indisplay1272#dz Cn2(z) #tex2html_wrap_indisplay1275#dt(z)#tex2html_wrap_indisplay1276#. |
|
|
(49) |
...
...
Tyler <#376#>et al.<#376#>[#18##1###] took advantage of the vector nature of
the displacement almost to eliminate the effect of chromatic
anisoplanatism on an adaptive-optics system by choosing an optimal
offset angle of a beacon from the propagation direction.