Re: Kohler illumination question...

So let me get this ... I have a Leica DMLS... and yes there is a peice
of frosted glass ... I never like it ...cuts down on available
light.... So lets say I take it out ... then what??

Thanks

David



On Tue, 26 Apr 2005 15:41:34 -0400, Andy Resnick
<andy.resnick@xxxxxxxxxxx> wrote:

>justbeats wrote:
>> Given that the final step is to hide it behind frosted glass, why is it
>> necessary to get a focussed image of the lamp filament when setting up
>> for Kohler illumination?
>>
>> I tried to answer this myself by taking images at different powers with
>> the filament defocussed to varying degrees. I couldn't detect any
>> difference in final image quality for any of the settings (as long as
>> the filament remains nicely centered of course).
>>
>> After unsuccessfully Googling for the answer, I've another (maybe
>> related) question. Is critical illumination considered an old and
>> inferior technique, or a modern and superior one?
>
>Well... the semi-obvious thing to do is remove the frosted glass.
>Truth is, the manufacturers put it (or a similar diffracting element) in
>the beam to pacify people who don't know how to properly align a scope.
> Honestly, or at least that's what my sales rep told me. So I make
>sure to remove it as a matter of practice.
>
>Critical illumination, for all practical purposes, is functionally
>identical to Kohler illumination. Both maximize throughput, both
>maximize the "performance" of the illumination system, etc. etc. Some
>people like critical, most prefer Kohler. Critical illumination
>generally means one ends up examining a magnified image of the bulb
>filament. (Guess which I prefer?)
>
>Hope this helps....

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