X-Ray Optics Metrology Laboratory

WYKO-TOPO Surface Profiler

The WYKO-TOPO surface profiler is a microscope-based instrument using visible light interferometry to measure surface finish (i.e., microroughness) of optical surfaces. The optical head can either use a 2D or a 3D detector. The 3D detector is used for measuring an area (on the order of a few mm x mm, depending on the objective) with a height resolution of 0.3 nanometer, while the 2D detector measures a one-dimensional profile with a height resolution of 0.1 nanometer.

Three different objectives are currently available: 1.5x, 5x, and 40x, which enable us to cover a wide range of spatial samplings (0.33-8.66 mm) and spatial frequencies (0.66-8.87 mm).


Photograph of the TOPO system with a Si substrate under evaluation.

The TOPO unit is mounted on a large optical table in order to accommodate mirrors up to 1.5 meters in length, and measurements can be performed on any location of the mirror surface.

To minimize the airflow-induced vibrations (through the optical table), the cleanroom airflow system is turned off during the measurements.