NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: G Becker
Date: 2013 Aug 21, 14:10 -0400
I can post a photo tomorrow. I don’t have a lab, so I have to set everything up. Just to clarify, only prisms cause rotation? If that is true, then it is the prism.
--Original Message-----
From: NavList@fer3.com
[mailto:NavList@fer3.com] On Behalf Of Brad
Morris
Sent: Wednesday, August 21, 2013 2:04 PM
To: george@gwbeckerpls.com
Subject: [NavList] Re: Request for
autocollimator help
Hello George
Kind of narrows down the choices of which prism is rotated, as there is only one.
A pure Cartesian shift of the prism (horizontally) would not cause a rotation in the optical bundle of light. An angular shift in the prism will indeed produce rotation in the optical bundle.
Is it possible to present an image of the 'skewed' result?
Brad
On Aug 21, 2013 1:08 PM, "G Becker" <george{at}gwbeckerpls.com> wrote:
Thank you for the response, but I had a typo in the first post. Only one prism, the three surfaces in the back are mirrors. The prism is vertically square, just off a hair on the horizontal.
-----Original Message-----
From: NavList@fer3.com [mailto:NavList@fer3.com] On Behalf Of Brad Morris
Sent: Wednesday,
August 21, 2013 12:56 PM
To: george{at}gwbeckerpls.com
Subject: [NavList] Re: Request for
autocollimator help
Hello George
I'll be the 'master of the obvious". One of the prisms is rotated relative to the optical path. This is based upon "askew", meaning twisted relative to frame of reference. Which prism is rotated? Couldn't tell you.
Master
of the Obvious.... Out
On Aug 21, 2013 12:24 PM, "G Becker" <george{at}gwbeckerpls.com> wrote:
Hello all,
I have a Davidson optronics autocollimator with a strange quirk. I called Davidson and asked if they could calibrate it. They declined and stated this autocollimator could not be calibrated.
This model has a lit grid screen that sits askew in the field of view. (Google askew, I assume that is a Google joke.) The first mirror the light path hits is adjustable. The adjustment is similar to the three screw Dobson main mirror adjustment. It then hits a prism with a lens glued to the top, leaves the prism and hits a second lens, then it hits two more 45 deg prisms and ends on the lit grid screen. Adjustments I have attempted, rotating grid screen in mount (does not help), systematically adjusting the first mirror (this seems to only help center on the lit grid). If I focus past infinity, I can see the back of the prism (it seems a little off line but vertical). The prism is hard mounted with no adjustment. If I run through the focus range I can count all the surfaces the light bounces off. Please suggest any possible ides to why the grid is askew.
Thanks
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