The thermal deformation property of silicon mirror with different porosity fabricated by direct laser sintering

The effect of the heat sink's porosity on the thermal deformation of the laser silicon mirror has been investigated in this paper. The water-cooled laser silicon mirror with different porosity structure has been fabricated by direct laser sintering and powder mixture of Cu-based alloy and NaCl. A Twyman-Green interferometer was employed to measure the thermal deformation of the silicon mirrors radiated by a high power laser. It is shown that the thermal deformation of the mirrors surface is related to porosity significantly. As the porosity increases, the thermal deformation decreases at first and then increases. With the heat sink porosity of 30.3%, the smallest thermal deformation of the mirror surface is obtained. The maximum thermal deformation of the mirror is 0.25 µm if the absorbed laser power density achieves to 5.3 × 105 W/m2.