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

["Nils Olof Carlin" <nilsolof.carlin@telia.com>]

Uwe wrote:

> 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

Just a guess: the idea is to take an image of a light source by the mirror,
and
1) dim the central portion representing large-scale features, thus enhancing
the "sidebands" that represent small-scale irregularities, and
2) phase-shift the central portion WRT the "sidebands", converting phase
differences to intensity differences.

2) may be done by the thin dark line on the film, or a semi-transparent
layer of soot.
1) may be done by the gelatin layer that tends to be thicker with some
silver mixed in.

Could Wolfgang's poor success with sharp lines be explained by too opaque
lines?

Just guessing here,

Nils Olof

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