Surface Metrology
Non contact surface metrology utilizes optical profilometry to measure the topography and roughness of microstructures with nanometer precision. This technique uses the properties of light to capture height information without touching the sample surface.
Height Mapping
Interferometric systems split a light beam into two paths where one reflects off the sample and the other off a reference mirror. Recombining these beams creates a pattern of fringes that shifts based on the vertical position of the surface. A camera captures these patterns while the sensor moves through a range of heights.
Software then reconstructs the three dimensional shape from the intensity data.
Vertical Resolution
The wavelength of the light source and the numerical aperture of the objective lens determine the smallest measurable height change. White light sources allow for a larger range of measurement without the ambiguity found in monochromatic systems. Resolution can reach the sub nanometer level on smooth surfaces.
Data Capture
Speed is limited by the frame rate of the camera and the movement of the precision stage. Dark or highly reflective surfaces require adjustment of the light intensity to avoid signal loss. The resulting point cloud is filtered to remove noise and calculate parameters like peak to valley height.
