Re: OPTICS FOR TASS: REFLECTOR OR REFRACTOR?

[Chris Albertson <chris@topdog.pas1.logicon.com>]

Tom Droege wrote:
> 
> Chris,
> 
> The chip is 30 mm wide, other than that, below seems correct.  What is
> the resolution of a normal camera lens?

It depends on the contrast of the test target.  At 1000:1
It is not hard to get 80 lines/mm.  Some 50mm macro lenses can do 100
and I would think a cheap lens could do 50. (This is for 35mm cameras. 
Lenses made for medium and large format cameras have have lower l/mm)
My point was just that you could maybe get by with lenses from
Edmund Scientific and a plastic tube.

If the CCD chip is 30 mm wide then has a smaller diagonal than a
35mm frame which is 36x24mm.  If you see vignetting then it is
likely due to baffles or a field stop and not due to the optics.
You could have the baffle removed from the lens.


Stupendous Man wrote:

>   The pixels are 15 microns each -- that's 67 pixels per mm.
> So, indeed, a lens which resolves 25 lines/mm will do the trick.

It is kind of tricky applying Nyquest thorem to a 2d sensor.  Our
sampling rate depends on if you draw a vertical line or a diagonal
line accross the CCD.  If you are conservative you say the pixels
are "up to" 15*sqrt(2) um apart.


-- 

--Chris Albertson

  chris@topdog.logicon.com                Voice:  818-351-0089  X127
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