Getting Started 
Agilent Cary 630 FTIR Spectrometer User’s Guide  21 
Laser Frequency Calibration test 
The Laser Frequency Calibration test measures the frequency (X-axis) 
accuracy. The test is conducted by measuring a spectrum of a 
polystyrene film. Absorbance frequencies from this spectrum are 
compared to frequencies set by NIST SRM 1921 polystyrene film. The 
software allows administrative-level users to use the test results to set 
the laser calibration. Laser calibrations should only be set after 
consultation with an Agilent technical support engineer. For this test, 
a background is measured first. After the background collection, a 
spectrum of polystyrene film is measured, as instructed by the 
software. For the Diamond ATR sampling accessory, no sample is 
required for a background measurement, but the polystyrene test 
sample must be pressed firmly against the diamond sample interface 
during the sample collection using the sample press attachment. 
Neither the multi-bounce ATR, nor the diffuse reflectance accessory 
measurements should be used for the laser frequency calibration test.