Calibration, Maintenance, and Troubleshooting
1919-R User Manual
101
accuracy at any wavelength in the range. This is an exclusive feature with Newport energy
sensors.
Figure
12-23 Absorption of Newport Pyroelectric Absorbers
12.4.2
Calibration
The sensitivity of the various Newport Pyroelectric sensors can vary from one to another as well as
with wavelengths. Therefore, Newport Pyroelectric detectors are individually calibrated against
NIST traceable standards. In addition, there is a wavelength sensitivity correction curve in the
meter.
Newport Pyroelectric detectors are calibrated using a 1064 repetitively pulsed laser referenced to
a NIST traceable Thermopile power meter. The average energy is set to the average power of the
standard power meter divided by the laser frequency. They are also calibrated with an excimer
laser at 248nm to correct the rather large absorption variations in that spectral region with those
sensors.
The spectral absorption of the detector coating is measured spectroscopically and the absorption
curve is used to correct the calibration for other wavelengths. When the user selects his
wavelength on the 1919-R, the correction factor for that wavelength is applied.
Photodiode Energy sensors are calibrated in a two-step fashion. First, the Photodiode detector -
filter combination are calibrated against a NIST traceable master over the wavelength range of the
sensor. Then, the sensor is calibrated at one wavelength using a 905nm repetitively pulsed laser
referenced to a NIST traceable Photodiode meter. The average energy is set to the average power
of the standard power meter divided by the laser frequency.
12.4.3
Accuracy of Calibration
Since the instruments are calibrated against NIST standards, the accuracy is generally 3% at the
energy level and wavelength at which the calibration has been performed. This accuracy has been
verified by checking the scatter of the results when several instruments are calibrated against the
same standard. The maximum error in measurement will be less than the sum of the specified
accuracy, linearity and inaccuracy due to errors in the wavelength curve.
The non-linearity is approximately 2%, and the error due to wavelength is described in
In addition to the above errors, the reading of Pyroelectric sensors changes with frequency. The
sensor has a built in correction for this error. For frequencies above 50% of maximum frequency,
inaccuracies in this correction can increase the total error by about 3%.
