MOOR INSTRUMENTS moorLDI2 RESEARCH USER MANUAL
49
the limit of the 12 bit A/D convertor). For distances of about 40 to 60 cm the
Factory Setup
gains of
2, 2, 2 will probably be ok for most measurements. Gain settings can be entered in the DC, Flux and
Conc boxes or the gains can be set automatically through
Gain Setup.
6.3.4.7 Auto Gain
The beam can be moved to any position on the tissue surface by right clicking the mouse. The gain
levels can be set automatically for that point (click
Auto Gain
).
There is large spatial heterogeneity of blood flow in many tissues so this technique may not be
reliable for all parts of the tissue surface. The Auto Gain facility could be used as a guide only
because the values are derived from one point only.
Gains need to be set according to the application: lower the gain when flux is high and the scan
distance is close (to avoid signal saturation, shown as white on the flux image and red on the photo
image); increase gains when flux is low and a longer scan distance is used (to make full use of
moorLDI sensitivity.
The image above shows a region of DC saturation:
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