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With laser interferometry, it is vital that the tuned wavelength of light is stable as
this is the base reference for all measurements. The Keysight
laser interferometry system is built around an in house designed and
manufactured Helium Neon laser source of great stability and long operational
life (50,000 hours). A testament to the stability of the laser head can be seen
from the results of wavelength checks in December 2001 (Figure 1) and December
2004 (Figure 2).
This shows a 9 year old Agilent long range (80m) laser head, regularly used for machine tool
calibration, which has been regularly calibrated by the NPL (National Physical
Laboratory, Teddington, UK). Each
calibration shows measurements of wavelength of light of the laser after switch on from
cold over a period of 12 hours. The mean vacuum wavelength for this laser tube
was reported as 632.991376 nm in December 2001 and 632.991377nm in December
2004, a change of 1 femtometre on the basic wavelength or 0.0016µm/m.
While this is the basis for an excellent laser calibration system, other factors
have far more influence on the final accuracy of a complete laser system. These
include, but are not limited to, sensor errors, optical alignment and
calibration uncertainties.
Figure 1 – Variation of laser wavelength with time. December 2001
Figure 2 – Variation of laser wavelength with time. December 2004
Back to Keysight Lasers or Calsure Calibration Software
C. D. Measurements Ltd., Chomlea House, Hadfield Road, Hadfield, Glossop, SK13 2ER, U.K.
Tel. 01457 852929
Email : sales@cdmeasurements.com
All Trade Marks Acknowledged
