Re: ATM Astigmatism

[Ricardo Dunna <rdunna@infolink.com.br>]

Rick

  Thereīs something more you can make to be shure. Find the astimatism
axis, thatīs done using the ronchi lines verticaly and rotating the
mirror at the stand some degrees up to the point that the swirl effect
doesnīt 
happens when moving the ronchi grating in and out focus.

  At that point the mirrorīs vertical and  horizontal diameters are the
longest and shortest ROC (you donīt know witch is witch). Just measure
the 
difference between ROCs with the focault measuring one diameter,
rotating  
the mirror carefuly 90 deg. without changing  the distance to focault
and 
measuring again. 

  You can follow the progress of any trial to defeat the astig this way.

Ricardo Dunna


> Now, is that not the case....seems if the light comes
> to a point at ROC, all light will be opposite outside
> of ROC as to what it is inside of ROC, therefore
> causing this shift, does that make sense, or should I
> try something else to determine for sure whether or
> not astigmatism does exist on the surface of this
> mirror.