From: "CSC" 
To: "Atm" 
Reply-To: "CSC" 


Sorry to be slow in response.  For TDE, just as the ronchi bands will hook
outward on the left and right sides of the mirror  when the grating is
outside focus(roc), they will hook inward on the left and right sides of
the mirror when inside of focus.

Opposite directions on opposite sides of focus.  Error is on the glass. TDE
outside focus    ][
TDE inside focus     [ ]


Your KE shadow will behave the same as a ronchi line as it crosses the
mirror.  Best place to analyze the "kinks" is when the shadow is
1/3 the way across the mirror.



If a small hook seems to be the in the same direction when you move the
ronchi grating or KE both inside and outside focus, you may be seeing a
diffraction effect of the grating.  Using a coarser grating, like 50 lpi,
can unscramble this illusion.

Same directions on opposite sides of focus.  Error is NOT on the glass.

Colin

-----Original Message-----
From: lifedata{at}vol.com [mailto:lifedata{at}vol.com]
Sent: Thursday, December 12, 2002 6:04 PM To: CSC
Subject: RE: ATM My TDE



>If you see the  edge of the shadow hook in opposite directions when
>you're well inside and well outside the focus area

Might you clarify "opposite directions?"  Do you mean the hooks
pointing away from each other on opposite sides of the mirror?  Away from
each other or toward each other - either one would be pointing in opposite
directions.

Jim L

--- BBBS/NT v4.00 MP