User`s manual

4200-DR Series LaserSource User’s Manual · Page 27
Menu Entry Description
I Set LoM Io set point, low range, slope
I Set LoB Io set point, low range, offset (mA)
I Set HiM Io set point, high range, slope
I Set HiB Io set point, high range, offset (mA)
Im Set M Im set point, slope
Im Set B Im set point, offset (μA)
V Set M Vf local sense set point, slope
V Set B Vf local sense set point, offset (V)
V Set Rm M Vf remote sense set point, slope
V Set Rm B Vf remote sense set point, offset (V)
I LoM Io measurement low range, slope
I LoB Io measurement low range, offset (mA)
I HiM Io measurement high range, slope
I HiB Io measurement high range, offset (mA)
Im M Im measurement, slope
Im B Im measurement, offset (μA)
V M Vf local sense measurement, slope
V B Vf local sense measurement, offset (V)
V Rem M Vf remote sense measurement, slope
V Rem B Vf remote sense measurement, offset (V)
When the slope is 1 and the offset is zero, this is considered an
“uncompensated” measurement. If you change either the slope or offset, the
value becomes “compensated” based on these values. The compensation
formula (a linear equation) is very simple:
Compensated = Slope * Uncompensated + Offset
The short form for Slope is typically ‘m’, and the short form for offset is typically
‘b’, which is why you see these letters used in the instrument menu (you will
often see this equation written as y=mx+b).
Depending on how you wish to calibrate, a simple offset calibration may be
sufficient, where only the offset value is adjusted and the slope is left at 1. This
level of calibration can be done using a single measurement, and if absolute
accuracy is only critical at a single point, this may be sufficient. For a slope and
offset calibration, you will need at least two points to compute the slope and
offset, and greater than two points can be used in a least-squares-fit algorithm.
Single Point Offset Calibration
Let’s say that you want to precisely calibrate the instrument at 300mA, and you
are using a 4205-DR in high range. You set the instrument at 300mA, observe
that the actual current is
298.6mA and the current measured by the 4205-DR is
301.2mA.