Re: [ATM] Zernike (or Lyot) phase contrast tests

[Guy Brandenburg <gfbrandenburg@yahoo.com>]

Thanks for the link, Uwe, but unfortunately I don't
read German. And, not having tried this myself, so I
don't know, but let me quote a couple of paragraphs
from Best of ATMJ2, page 339, article by Herbert
Highstone:

"Photographing phase contrast images requires a
specialized film with extremely high contrast and
resolution. Ordinary films give mediocre results. For
the photographs printed in this article, I used 35-mm
Kodak Ektagraphic HC slide film that has a Kodalith
emulsion. It was successfully developed and printed
just like any other black-and-white film by my local
photo shop using their standard B&W processing methods
(special processing is not requited).

"I used 10-minute exposures with an extremely sharp,
15-inch f/9 "process" lens of the kind used in
printing shops. (snip ... ) Please note that ordinary
camera lenses may not have the necessary sharpness.
You should bracket widely to ensure usable results. Be
careful to avoid any vibration of your equipment
during the long exposures. Ektagraphic HC slide film
has a resolution of 700 line pairs per millimeter; and
it can provide sharp, grain-free enlargements with
plenty of fine detail."

This seems to directly contradict what you were
saying, Uwe. What is your response?

Guy

--- "Uwe Süßenberger" <u.suessenberger@t-online.de>
wrote:
> Hello Guy,
> 
> From: "Guy Brandenburg" <gfbrandenburg@yahoo.com>
> > How many people have ever performed one of those
> > Zernike Phase Contrast Tests to examine surface
> > roughness? I have just been reading about them in
> Best
> > of ATMJ #2 and it all looks fairly easy to make,
> and
> > rather useful and informative as well. There is
> just
> > one problem: It says that if you want to make a
> > photograph, you have to make 10-MINUTE exposures
> with
> > Kodalith film!!! That must mean that the images
> are
> > EXCEEDINGLY dim...
> 
> afaik, the kodalith is not used for taking an image
> of the surface-roughness but it serves as a screen
> on which a 0.1mm bar is been used as
> phase-shifting-device. Instead of kodalith you may
> use TP 2415. For construction details see:
>
http://home.t-online.de/home/wolfgang.rohr/phaskont.htm
> The phase-contrast image itself may be taken with
> any (digital-) camera.
> 
> Kind Regards: Uwe
> _______________________________________________
> ATM mailing list http://www.atmlist.net/
> 


=====
Guy  BrandenburgWashington, DChttp://home.earthlink.net/~gfbranden/GFB_Home_Page.html
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