<title>Hybrid analysis of optical elements by interferometry and thermography</title>

Abstract

Effects of thermal deformations of optical elements may be visualised and measured by interferometric methods. They correspond to the deformation of heated optical surface and/or deformation of the wave front of the light beam propagating through optical elements. In one of the experiments the optical effects for a single optical element heated by CO2 laser were measured. Single element was combined with the second optical element for spherical aberration correction. The measurement stand used was composed of five modules: interferometers in Fizeau or Twyman -Green configuration (He-Ne, aperture 100 mm), CO2 laser with the device for changing and measuring the power of the laser beam, the substrate module, thermovision camera AGEMA 470 for temperature measuring and the module for control, registration and analysis of interferometric images. The results of measurements provide the form of the wave front shape in combination with the thermal gradient of the surface. The experimental results are compared with computer simulated effects of the optical path difference and the temperature distribution calculated by the finite element method.