On 2008-11-18, cavelamb himself wrote:
DoN. Nichols wrote:
On 2008-11-17, Gunner wrote:

[ ... ]

If anyone wants to know why most specialists prefer fixed power
optics, Id be happy to expound.

[ ... ]

Could it be that the position of the cross-hairs shifts relative
to the target when the focal length is changed, so you have to zero it
at one focal length? (Or even worse -- the sliding components which
implement the zoom may shift with recoil, so even if you stay at a given
zoom point the cross hair point will shift.

Enjoy,
DoN.


Absolutely correct, DoN.

But it can be correct in software!

The predictable parts like the shift in point as you zoom -- but
I'm not sure about the shift resulting from recoil -- in the absence of
the alternate boresighted sensors (visible, IR, and intensified/near-IR)
which could be checked against each other.)

What the heck, I guess I can publish some of it now?

I forget how long it takes for something to be automatically
declassified. I guess that the 80186 and the Z80 sort of date it. :-)

Some notes from an early development project.

Note the hysteresis diagram on the 4th page down...

http://www.home.earthlink.net/~cave-1/

Hmm --- 2-1/2 generation image intensifier?

1st generation was one up to three cascaded intensifier tubes
with electrostatic lenses. Each stage inverted the image, and the
objective lens also inverted so you wound up right side up at the
eyepiece with a three-stage intensifier..

2nd generation was single stage with a microchannel amplifier
plate and proximity focus.

Not sure what the 2-1/2 gen would have been. Maybe a 2nd gen
intensifier married to a videcon?

My memories come from the Army Night Vision Labs. Yours from a
contractor perhaps?

Enjoy,
DoN

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