Ophir Optronics Ltd QSR Manual Do Utilizador

The sensitivity of the various Ophir pyroelectric sensors vary from one to 
another, as well as with wavelengths. Therefore, Ophir pyroelectric detectors are 
individually calibrated against NIST traceable standards. In addition, the 
calibration is corrected in the device for different wavelengths. 

Ophir pyroelectric detectors are calibrated using a 1.06µm repetitively pulsed 
laser referenced to a NIST traceable thermal power meter. The average energy is 
set to the average power of the standard power meter, divided by the laser 
frequency. The metallic PE25 and PE50 heads are also calibrated with an 
excimer laser at 248nm to correct the rather large absorption variations in that 
spectral region with those heads. 

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 in the StarLab application, the correction 
factor for that wavelength is applied. 

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%. For error due to wavelength, refer to  
Table B-3.  

In addition to the above errors, the reading of a pyroelectric head changes with 
frequency. The device has a built-in correction for this error. For frequencies 
above 50% of maximum frequency, inaccuracies in this correction can increase 
the total error up to 3%. 

The maximum error in measurement will be less, and in general will be 
considerably less, than the sum of the above mentioned errors.