Laser Scanning Microscopy for Tomographic Imaging of Roughness and Point Absorbers in Optical Surfaces

19 December 2024

High-precision laser interferometric instruments require optical surfaces with a close to perfect contour, as well as low scattering and absorption. Especially, point absorbers are problematic because they heat up and locally deform the otherwise flat surface, resulting in correlations between absorption and contour. Here, we present a spiral laser scanning microscopy approach for the reconstruction of the 2 complementary images of an optical surface. The “phase image” is related to the surface profile including roughness. Our
experiment achieves a sensitivity of up to (3.1±1.4) fm/√Hz with a (5.29±0.06)-μm transversal resolution. The “loss image” localizes point absorbers. The 2 images show correlations for some features proving the particular strength of our tomographic approach, which should help further improving optical surfaces or to understand dynamic processes of surface physics.

Publication finde here:

Advanced Devices & Instrumentation