#Note in advance: My first posting was rejected, I do not know why, with the
#answer I attach at the end. Please excuse if you get this mail twice.
 
 
I have a question concerning the resolution of the confocal microscope:
 
Normally the resolution of a confocal is given as the distance by which two
points must be separated to resolve them in two points (about 300x600nm x,y
and z.). But this is not the type of experiment I am interested in. I want
to determine the gravity centers of point-like Fluorescence in situ
hybridization signals (cosmid or YAC-probes) and then (by 3D image analysis)
the shortest distance of these gravity centers to a nearby surface of a
large structure recorded in another color (a chromosome). This larger
structure has a strong gray-level increase over several pixels at the border
and in the core the gray-levels move around a mean.
 
My questions are:
(1)  How accurate (in nm) can the gravity center of a point like signal can
be determined (relative to other signals) and
(2)  How accurate can the position of a "surface" be determined, lets say at
a particular threshold?
 
I am working on a Leica TCS System and use mainly the 63x, 1.32NA PL APO lens
 
Any ideas about it?
 
Greetings
 
Steffen Dietzel
 
 
#and here comes the error message I got after the *first* posting
>Your message  is being returned to  you unprocessed because it  appears to have
>already  been  distributed to  the  CONFOCAL  list.  That  is, a  message  with
>identical text  (but possibly with different  mail headers) has been  posted to
>the list recently, either by you or by  someone else. If you have a good reason
>to resend this message to the list (for instance because you have been notified
>of a hardware failure with loss of  data), please alter the text of the message
>in some way and  resend it to the list. Note that  altering the "Subject:" line
>or adding blank  lines at the top  or bottom of the message  is not sufficient;
>you should  instead add a  sentence or  two at the  top explaining why  you are
>resending the  message, so that the  other subscribers understand why  they are
>getting two copies of the same message.
>
>------------------------ Rejected message (58 lines) --------------------------
>
 
-- -------------------------------------------------------------------
Steffen Dietzel
Institute of Human Genetics, University of Heidelberg
Im Neuenheimer Feld 328, D-69121 Heidelberg, Germany
phone:+49/6221/56-3998 or -3119 fax: -5332
personal e-mail: [log in to unmask]
listservmail: [log in to unmask]
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