Variable Conditions In Taking Readings; Calibrating With Distilled Water; Operating Instructions - Leica Abbe Mark II Manual De Instrucciones

T T h h e e m m o o d d e e s s e e l l e e c c t t o o r r s s w w i i t t c c h h i i s s u u s s e e d d t t o o s s e e l l e e c c t t m m e e a a s s u u r r e e m m e e n n t t m m o o d d e e s s : :
T T h h e e m m o o d d e e s s a a r r e e : :
• % Solids-TC - Temperature Compensated % Solids as Sucrose
( Brix) per International Commission for Uniform Methods of
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Sugar Analysis Refractive Index Tables.
• n - Refractive Index
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• % Solids - Non-Temperature Compensated % Solids as Sucrose
The reticle adjustment access hole permits vertical adjustment
of the crosshair during calibration procedures.
Depress the read display button to obtain measurement values.
Depressing the temperature display button will provide
a reading of the prism temperature.
Readings are shown digitally in the display window.

5.1 Variable Conditions in Taking Readings

Distilled water readings above 20
refractive index % Solids-TC mode, assuming the instrument is
properly calibrated. Correct readings cannot be obtained in the
non-temperature compensated % Solids mode when the water
sample temperature is above or below 20
readings for distilled water can be obtained from 0
Chart 1 for values between 18-30
Refractive index is inversely proportional to temperature. As
temperature increases, the solution density decreases and the
refractive index or % Solids reading will decrease. As tempera-
ture decreases the solution density will increase and the
refractive index (% Solids) will increase. The % Solids-TC mode
automatically corrects the reading for temperature based on
the temperature coefficient of sucrose in solution. This coeffi-
cient is typical of most aqueous solutions.

5.2 Calibrating With Distilled Water

To calibrate:
1. Place a distilled water sample on the measuring prism surface
and let it stand undisturbed for 3-5 minutes to obtain temperature
stability. Turn the mode selector switch to the refractive index
(n ) position.
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2. Focus the eyepiece until the crosshair clearly appears.
3. Rotate the adjustment control clockwise until the shadow line
nearly meets the crosshair. Use the dispersion correction wheel
to obtain the sharpest possible color-free shadow line. Adjust the
Dispersion Correction Wheel
Adjustable Eyepiece
Reticle Adjustment
Access Hole
Display Window
Read Display Button
Temp. Display
Button
Power Switch
F F i i g g u u r r e e 1 1
4 English
C can be obtained in the
O
C. Refractive index (n )
O
D
O C to 80 O C (see
O C).
Prism Surface
Illuminator Arm
Adjustment
Control
Right Panel Cover
Mode Selector
shadow line to meet the crosshair. Press the Read button and
record the n value, then press the temperature button and
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record the temperature.
4. If the instrument is properly calibrated, the reading will be
1.3330 less 0.0001 for each degree above 20
each degree below 20 O C.
If the instrument is not calibrated, determine the proper reading
(Chart 1) and rotate the adjustment control and depress the READ
display button until the display reads correctly. (The shadow line
will no longer intersect the crosshair on the reticle.)
5. Insert a 1/16" Allen wrench into the reticle adjustment
access hole (Figure 2) located in the dispersion correction wheel.
Turn the wrench to bring the crosshair into proper position on the
shadow line.
N N O O T T E E : : The final movement made with the adjustment
correction control wheel should always be in a clockwise direc-
tion. The shadow line will move upward.
6. Turn the mode selector to the BX-TC position. Press the READ
button. An LED reading of 000.0 or 0.1 is normal. If a negative sign
and a decimal point appear, no reading can be given.
Go on to the next step.
If a "No Reading" condition persists after repeated READ
attempts, rotate the adjustment control until the display reads
000.0 or 0.1. Only a very slight adjustment will be necessary.
Readjust the reticle crosshair to the shadow line.
The display should now read 000.0.
Repeat the steps until the display reads 000.0.

6.0 OPERATING INSTRUCTIONS

To begin operation:
1. Open the prism assembly cover (Figure 4) and remove the
protective lens tissue. Clean the measuring prism surface with
alcohol and then distilled water. Wipe with a clean soft cloth or
lens tissue, but do not wipe the measuring prism surface while
it is dry. Any residue left on the prism can affect the accuracy
of readings.
2. Turn the mode selector to the desired mode position.
3. Apply a sample solution to the measuring prism surface using a
glass dropper. Close the prism cover and position the illumination
arm so that the exposed face of the upper prism is fully illuminated.
4. Turn the dispersion correction wheel so that the crosshair
adjustment access hole is at the six o'clock position.
Reticle Adjustment
Access Hole
F F i i g g u u r r e e 2 2
C or plus 0.0001 for
O