Laboratory for optical metrology

The laboratory for optical metrology includes the two main fields of research:

  • In-process measuring methods and
  • Surface integrity evaluation.

The focus "In-process measurement methods" concentrates on the surface assessment with scattered light and other methods as well as the determination of (primarily) mechanical workpiece loads during manufacture.

The used light scattering methods allow a quick, in-process determination of (statistical) surface characteristics, without detecting the actual topography of the component. The procedures can be applied to investigate fast moving component surfaces in the manufacturing process. In addition to assessing the mean roughness in the observed measurement spot, statements about structure heights and widths as well as individual defect classes of components are possible. This evaluation can be applied not only for structure areas with sizes above the optical wavelength, but also for structures in the nanometer range (below the optical wavelength) due to the use of the rigorous scattering theory based on Maxwell equations. The measurement methods are investigated with simulative and experimental approaches leading to results about measurement resolution and uncertainty for specific applications as well as general measurability limits.

Technical specifications

The laboratory equipment is located in several optical measuring rooms with laser protection devices and includes the following systems:

→ Various measuring devices for scattered light-based surface characterization

  • Own developments
  • Measuring ranges
    - Roughness: 20 nm - 2 µm
    - Frequency: up to 100 Hz

→ White light interferometer (Agos)

→ Tactile roughness for comparative studies, for example:

  • Mitutoyo CS5000
  • Mahr perthometer
  • Mahr LD120

→ Reference measuring system for high-resolution light scattering measurements

  • Own developments
  • Detected angular range: almost 4π,
  • Angular resolution: 2 arcsec

→ Measuring systems for in-process measurement of deformation of components

  • Measurement frequency: up to 180 Hz
  • Lateral resolution: ≈ ​​2 µm
  • Deformation resolution: ≈ ​​60 nm

→ 2-Frequency Interferometer (Jenoptik)

→ Various measuring systems for photothermal surface integrity analysis
with different laser sources

  • Own developments

→ Micromagnetic measuring station (3MA) for comparative studies

Services

  • Feasibility studies on the application of measurement principles, particularly in manufacturing and heat treatment processes,
  • Development of measuring methods for industrial applications,
  • Basic research for new measurement methods in the two fields of research,
  • Simulation and measurement of light scattering on micro- and nano-structured workpieces to assess the structural quality,
  • Destructive surface integrity/topography checking by comparison with reference samples.


Contact Details

Dirk Stöbener
E-Mail: Enable JavaScript to view protected content.
Phone:+49 (0)421 218 646 40