Fabrication of a thermally actuated tunable grating and its application as a CO2 laser beam profile analyzer

We propose a thermally actuated tunable grating for measuring the beam profile of a CO(2) laser. The grooves of a transmissive grating are filled with a liquid whose refractive index depends on temperature. A visible laser as a probe and a CO(2) laser as a heat source are illuminated on the grating. The CO(2) laser is absorbed, and depending on its beam profile, a temperature profile is induced on the grating. The refractive index of the heated liquid is changed, resulting in a change of efficiency of the grating for the probe laser. By using the 1st orders of diffraction in a 4f imaging system, the beam profile of the CO(2) laser is imaged onto a CCD camera by the probe laser.