Temperature-dependent perturbations on LTP measurements

The Long Trace Profiler (LTP) has proved to be one of the major metrological aids for the characterization of synchrotron radiation optics. Currently the optical components installed at the beamlines face higher and higher demands, requiring a precise calibration and control of the measuring conditions. One important parameter to be considered while scanning is the temperature drifts afflicting the measuring sessions. We will review our experiences about the influence of this parameter on the LTP ability in measuring very accurate optical surfaces. It is possible to discriminate at least four major sources of perturbations due to temperature changes: air turbulence, deformation in the optical train inside the LTP optics head, deformation of the optical surface under test (SUT) and deformation of the holders of the SUT itself. Some addresses on the curing of these perturbations can be obtained.