User`s manual

5.10.2 SoftCal™ Accuracy with DT-400 Series Silicon Diode Sensors 83
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5.10.2 SoftCal™
Accuracy with DT-400
Series Silicon Diode
Sensors
A SoftCal™ calibration is only as good as the accuracy of the calibration points. The
accuracies listed for SoftCal™ assume ±0.01 K for 4.2 K (liquid helium), ±0.05 K for
77.35 K (liquid nitrogen), and 305 K (room temperature) points. If you are performing
the SoftCal™ with Lake Shore instruments, note that the boiling point of liquid cryo-
gen, though accurate, is affected by atm
ospheric pressure. Use calibrated standard
sensors if possible.
One-point SoftCal™ calibrations for applications under 30 K are performed at liquid
helium (4.2 K) tempera
ture. Accuracy for the DT-470-SD-13 diode is ±0.5 K from 2 K
to <30 K with no accuracy change above 30 K.
Two-point SoftCal™ calibrations for applications above 30 K are performed at liquid
nitrogen (7
7.35 K) and room temperature (305 K). Accuracy for the DT-470-SD-13
diode sensor is as follows:
Two-point SoftCal™ calibration
accuracy for DT-470-SD-13 diode sensors
±1.0 K 2 K to <30 K (no change below 30 K)
±0.25 K 30 K to <60 K
±0.15 K 60 K to <345 K
±0.25 K 345 K to <375 K
±1.0 K 375 to 475 K
Three-point SoftCal™ calibrations are performed at liquid helium (4.2 K), liquid nitro-
gen (77.35 K), and room temperature (305 K). Accuracy for the D
T-470-SD-13 diode
sensor is as follows:
Three-point SoftCal™ calibration
accuracy for DT-470-SD-13 diode sensors
±0.5 K 2 K to <30 K
±0.25 K 30 K to <60 K
±0.15 K 60 K to <345 K
±0.25 K 345 K to <375 K
±1.0 K 375 to 475 K
5.10.3 SoftCal™ With
Platinum Sensors
The platinum sensor is a well-accepted temperature standard because of its consis-
tent and repeatable temperature response abov
e 30 K. SoftCal™ gives platinum sen-
sors better accuracy than their nominal ma
tching to the DIN 43760 curve.
Acceptable temperature range for platinum SoftCal™ sensors
SoftCal Point One
Liquid nitrogen
boiling point
77.35 K
SoftCal Point Two
Room temperature
point
305 K
SoftCal Point Three
High temperature
point
480 K
50 – 100 K 200 – 325 K 400 – 600 K
650600550500450400350300250200150100500
One, two, or three calibration data points can be used. If you are using one point, the
algorithm shifts the entire curve up or down to meet the single point. If you are using
two points, the algorithm has enough information to tilt the curve, achieving good
accuracy between the data points. The third point extends the improved accuracy to
span all three points.
TABLE 5-6
TABLE 5-7
FIGURE 5-10