Measuring surface flatness is extremely important for the functional use of many glass products or precision mechanics involved in holding optics and glass components. This involves characterizing the surface flatness for the most diverse areas of use. Whatever the application, Polytec offers optical measurement and testing solutions for reliable inspection of flatness on glass. Large-area measuring white-light interferometers of the TopMap optical surface profiler series measure the surface flatness of entire areas very quickly, without contact on a large field-of-view (FOV), gathering precise 3D insights with a precision down to the nanometer and even subnamometer range. TopMap surface metrology is used for form parameter and flatness evaluation in both the metrology lab and close to production. These non-contact surface profilers continuously record height data at selected points in real time for immediate feedback regarding the production process. This flatness measurement keeps product quality high and saves cost for later defects, malfunction and repair.
Surface flatness – tactile or optical measurement
Focusing on surface flatness as critical form parameter, this precision-manufactured mirror holder is a complex structure and workpiece with functional surfaces. Narrow portions can twist and distort during and after manufacturing. The effect of these distortions is to move the mounting surfaces and misalign the mirror. If the surface flatness of the mounting surface falls below a critical value, the mirror will be out of alignment and will not work properly.
The mounting surface is very intricate and is made up of relatively narrow, partially recessed ligaments. It was impossible to determine the surface flatness with a conventional tactile profiler or sensor system because only a small portion of this surface was accessible to the scanner tip. Unlike tactile profilers, this situation was easily solved with a TopMap topography measurement system. The non-contact optical measuring procedure allows the areal characterization of almost any surface, independently of its specific geometry constraints, resulting in reliable pass-fail analysis.