To: Laserman
adaptive optics cannot correct for thermal blooming if it is present.
however
wrt dwell time on the target,
this is not a problem if the target is rapidly moving.
The presence of absorption is not sufficent to conclude that there is
thermal blooming. One of the most important factors is how long any
parcel of air spends in the beam.
and if the beam slew is sufficiently large to prevent thermal
blooming from developing into a significant effect. Also, the beam is strongly
focused, making the dwell time in the beam even smaller.
For small scale blooming, the conversion of absorption into index of
refraction fluctuations does not occur near the beam director. The
turbulence-induced phase fluctuations must propagate to turn into
scintillations first. For even small beam slews, the beam is moving so
fast by the time this occurs that there is simply no time to heat the
air before the beam passes.
some JASON involvement before the JASONs were history
44 posted on
10/27/2003 3:55:49 PM PST by
inPhase
To: inPhase
AO does help under certain conditions. The simulation codes and the experimental data were developed in the 70's (I did some of it), and repeated with greater fidelity recently that showed some AO utility. However, with turbulence you can develop a phase compensation instability that further limits its utility.
Worked in SDI myself as well as other national review panels.
55 posted on
10/27/2003 5:21:00 PM PST by
Laserman
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