Night Vision risley prisms

[wigwamitus]

There seems to be some confusion about how "real" clipons whether thermal or i2, come to be "collimated" ...

The trick is done with prisms ... sometimes called "risley prisms" ... these sit on the rear end of the device and when properly rotated ... the device in question is said to have been "collimated". This requires the use of a piece of equipment called a "collimating table". The result is a device, which, within tolerance, will shift the image as required, to align the optical paths of the clipon and the day scope.

Note, that "real" clipons, such as the PVS-30 or the UTC-x do not have external or menu adjustabilty for boresight. If you mount the clipon and the day scope so that the offsets are within tolerance, you will be dead on ... out to 900 yards, in my experience, with both the UTC and the PVS-30. The tolerance for the PVS-30 is at least 0.2 inches and for the UTC at least 0.1 inches ....

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"wanna be" clipons ... do not have these risley prisms and hence by definition, cannot be collimated. For those sort of widgets, you must line them up with the day scope, "exactly" if possible ... and or use menu driven adjustments to try to get things lined up. And such alignment might work within a certain tolerance of distance ... such as between 50 to 150yds ... but not at any distance ... such as out to 900yds.

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The real clipons are expensive for a reason ... and risley prisms that have been collimated on a colliating table are a part of that cost. They are what make devices such as the PVS-30 and the UTC "magic" and able to be moved from rifle to rifle with no adjustments.


https://www.lens.org/lens/patent/175-421-927-693-087

https://www.photonics.com/Article.aspx?AID=25652

 

[ballistic1]

What do you think about a standalone risley prism on it's own qd pic rail mount, set to correct height center matching whatever clipon unit is in front of it... so it cd be mounted directly behind said clip on.. to act as a collimating device..

I ask because many units do not have a way to mount a collimator into the eye piece.
But a stand alone pic rail mounted collimator would allow this.. in theory..

With obvious things like needed to placile it on a a collimation table, etc .. just an idea
I had when reading this post

 

[wigwamitus]

Well, there are critters like this ..

https://www.bhphotovideo.com/c/prod...h_zl_pvs14_universal_riflescope_to_pvs14.html

Which replaces the prism alignment with mechanical alignment for those devices that have no adjustments.

And it would be possible to make such devices for other optics.

You would still need to get a close as possible in terms of height, as this mechanical sort of alignment will only work out a certain distance ... the closer the starting point for the alignment to less divergence you will see downrange.

 

[ballistic1]

So a mount with a built in sliding ramp for height, lateral, and longitudinal.. x,y, and z axis
. ie, precision micro height adjustable would be requisite for such a stand alone risley prism

In that the mount could be micro precision moved/ tuned, to be side to side, up or down, or forward or rearward, along the pic rail

 

[wigwamitus]

The risley prisms need to be in a "module" that allows them to rotate.

 

[ballistic1]

Yep.. there is no reason why it couldn't be mounted in its own housing, so it could
be turned inside itself to collimate.. but still be effectively moved via the mount to proper positioning

 

[wigwamitus]

Ok, you're hired ... let's get to work !!!

 

[ballistic1]

Deal! ?

Should try this principle on the Patrol

 

[Squibbler]

I call dibbs on the first unit!

 

[Prebanpaul]

My name is Risley, quit trying to circumvent perfection. There is a reason why we are expensive.

 

[Frog05]

Following! I want to see where this joint venture on the Patrol goes.