Newport LDC-3706 Series, Руководство пользователя

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December 2019 109 LDC-3706 Series Laser Controller
When the LDC-3706 instrument is shipped from the factory, the LM335 measurement system is
calibrated, but the sensor (C
1
and C
2
) is not. Nominally, C
1
= 0, and C
2
= 10. In that case, the
temperature accuracy is typically ±1
°
C over the rated operating range. With C
1
and C
2
calibrated
also, the temperature accuracy is typically ±0.3
°
C over the rated operating range. The
temperature accuracy may be improved over a narrow temperature range by a two-point
calibration of C
1
and C
2
. However, the LM335 is not perfectly linear, and even with C
1
accurately
known (and C
2
uncalibrated) there is a non-linear absolute temperature error associated with
the device. This non-linearity caused error is typically ±0.3
°
C, with the error associated with C
1
assumed to be zero.
If a maximum absolute error of ±1
°
C is tolerable, no calibration of C
1
or C
2
is required, just set
C
1
= 0, C
2
= 10. If a maximum absolute error of ±0.5
°
C is tolerable, the one point calibration of
C
1
may be used. If a greater accuracy is desired, the two point method of determining C
1
and C
2
should be used. Note however, the absolute error associated with the constant C
2
may vary
over different temperature ranges.
One Point Calibration Method
This procedure will work for any linear IC temperature sensor. The accuracy of this procedure
depends on the accuracy of the known temperature, externally measured. It is used to
determine the zero offset of the device, and it assumes that the gain offset (slope) is known
and is correct.
1. Allow the LDC-3706 instrument to warm-up for at least one hour. Set the sensor to
the desired sensor type, and RECALL the constants for the particular device to be
calibrated.
2. Select the C
1
parameter. Read and record the value of C
1
.
3. Place the sensor at an accurately known and stable temperature, T
a
. Connect the
sensor to pins 14 and 15 of the LDC-3736 or LDC-37620 25-pin connector or pins 7
and 8 for the LDC-3726. Set the LDC-3706 instrument for normal constant
temperature (T mode) operation. Allow the LDC-3706 instrument to stabilize at the
known temperature, T
a
and read the displayed temperature, T
d
.
4. Determine the new value of the offset, offset-new, from the formula:
− = + −
and replace the previous offset value with the newly calculated value by selecting the
offset parameter and entering the offset-new value.