To: atm{at}shore.net
From: tkrajci{at}san.osd.mil
Reply-To: tkrajci{at}san.osd.mil


>From: "Jack Schmidling" 
>
>From: "Tom Krajci" 
>
>> >Assuming they are all like this, how is it possible to align things
>> whenlooking off axis with the diagonal blocking an on axis view.
>>
>> You can view the reflection of the laser collimator's face (shoved in
>> the focuser tube) by looking at the main mirror, or you can use a
>> handheld mirror to 'peek' around the secondary if the secondary blocks
>> your view.........
>
>I understand the procedure.  I was wondering how it can be lined up if one
>is viewing off axis.
>
>Wouldn't the fact that one is viewing from off center cause an error in
>the alighnment?

Based on how I understand it, no.

You are projecting laser spots on surfaces.  On that same surface are other
marks (center ring on mirror, center spot on laser collimator's face. 
Because the spots and marks are all on one 'two dimensional'
surface...tilting that surface should not affect how 'centered' the
spots/marks appear.

To test this idea, draw a circle on a sheet of paper and put some
concentric marks in that circle on the same sheet of paper.  View the paper
'square on' and from various oblique angles.  The marks should always
appear concentric...just that from the oblique angles the circle will look
like an ellipse.

However, if there is a '3D' aspect to your surfaces, spots, etc...then
viewing from off axis will make alignment difficult, if not impossible.

Tom Krajci
Tashkent, Uzbekistan

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