6. LSServer, Scanner Shell and Download
2004-11
Operating Manual for the LS Series Scanner No. 30001798 Rev. No. 1.5
6-45
Z-Scan Height
Z-Scan Height
group box
•
Slide Thickness
static edit box
The
Slide Thickness
static box gives information about the current slide
thickness that has been defined in the Geometry Parameters tab.
The Slide Thickness is considered in displaying the slide scheme and
needs to be defined for searching the focal plane within an appropriate
range.
•
Z-Scan End
controls
Use the
Z-Scan End
controls (µm) to enter the
End
value of the
autofocus z-scan (= scan in vertical direction). Use the arrows or type in
the value manually.
•
Z-Scan Start
controls
Use the
Z-Scan Start
controls (µm) to enter the
Start
value of the
autofocus z-scan (= scan in vertical direction). Use the arrows or type in
the value manually.
For a Standard.saf file, the default start and end values for the autofocus
search area are +/- 800 µm. The range considers the tolerance of the
slide thickness, the tolerances of positioning the slide adapter to the
instrument as well as internal tolerances of the instrument itself. However,
it might be necessary to increase the z-scan to guarantee that the
algorithm finds the focal position reliably.
Higher autofocus search areas (increased z-scan distances) prolong the
time for autofocus determination.
Focus Offset
Focus
Offset
controls
•
Focus Offset
controls
Use the
Focus Offset
controls (µm) to measure a certain value below or
above a focal plane. Set the value by spinning the arrows or by typing in
the offset manually.
In certain cases the autofocus plane and the scan plane might differ, for
instance: - slides with cover glasses, slides with membranes or filters. A
certain value can be set as focus offset to perform the scan below (-) or
above (+) the focal plane.
E.g.: For a cover glass with a thickness of 170 µm, the correct focus
offset would be 113 µm, - calculated according to following formula:
Formula for the offset:
d-[(n-1)/n]*d
n= refractive index of the cover glass (= 1,5)
d= thickness of cover glass
