[RASMB] question for XLA experts

[Borries Demeler]

Hi,
I am trying to calibrate our rotors for speed-dependent rotor stretching 
and the channel positions of our centerpieces. The problem I am facing is
that it seems to be very difficult to assign the exact bottom of a channel
to a peak from an absorption scan.

Attached is a typical absorbance scan of an empty 6-channel centerpiece.
For the first channel, I labeled the peaks 1-10 and found the radial
positions for them, shown below:

1 = 5.741
2 = 5.768
3 = 5.790
4 = 6.125
5 = 6.138
6 = 6.186
7 = 6.234
8 = 6.249
9 = 6.273
10 = 6.286

I then scanned the centerpiece on a 3200 DPI scanner and came up with
these dimensions (believe it or not, a half-way decent scanner does a
pretty good job at measuring small parts, good to within +/- 0.01 mm!)

Cell dimensions:

first channel: 3.83 mm, darkspace: 1.27 mm (channel width: 3.29 mm)

Now can someone tell me which peaks correspond to the channel bottom?
Or won't I be able to find it correctly with absorbance optics, should
I use interference optics? I guess IF has a better radial resolution,
is it also as accurate as the absorbance radii?

Any suggestions would be appreciated.

-Borries
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