Calibration; Calibration With Standard Solids - PCE Instruments AR3 Betriebsanleitung

4. Calibration

4. Calibration

4.1 Calibration with standard solids

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Before taking any measurements, the calibration of the
scale must be checked. Two possible ways of doing this
are described as follows:
After switching the instrument on turn the locking knob
clockwise and lift up the illuminating prism. Put a few
drops of contact liquid on the measuring prism before
placing the polished surface of the standard glass block
on the measuring prism. Make sure that there are no
air bubbles between the two surfaces.
The standard glass block must be slightly covered by
the illuminating prism. This is done so that the direct
light is reduced otherwise an over-exposure will occur
which would make an exact calibration impossible.
Look through the eyepiece and turn to the left or to the
right until it is possible to see the reticle clearly.
Then turn the scale knob to the value marked on the
standard glass block.
Then eliminate the colour round the light/ dark line with
the compensation knob, the separation line must now
lie on the point of intersection of the reticle.
If this is not the case, adjust the position of the light/
dark line by turning the adjustment screw on the front of
the refractometer, with a screwdriver, until it lies exactly
on the point of intersection of the reticle.