Optical coherence tomography: non-destructive optical testing

Optical coherence tomography (OCT) is a non-invasive imaging technique that can be used to tomographically examine transparent and semitransparent materials. The operating principle of OCT is similar to that of ultrasound imaging. However, unlike ultrasound, OCT works with light rather than sound waves. OCT provides depth-resolved cross-sectional images and volumetric images with a penetration depth of several millimeters and a resolving power in the single-digit micrometer range – about ten times better than ultrasound.

OCT has so far been used mainly in non-contact biomedical diagnostics. The measurement method is based on short-coherent interferometry and allows the diagnosis of the fundus of the eye within seconds using high-resolution cross-sectional images or the volumetric imaging and differentiation of tissue layers. The advantages of OCT can also be exploited in numerous industrial production applications.

In numerous research and industrial projects, Fraunhofer IPT has explored and developed the potential of OCT beyond biomedical diagnostics: Whether it is the high-resolution measurement of thin layers in the printing industry or the in-line integration of OCT for coaxial process monitoring of laser processes. In (semi-)transparent materials such as plastics, films or paints, OCT allows insight into deeper layers and thus opens up the inspection of application quantities as well as the detection of air inclusions or other defects. In metal processing, surface features and shape deviations can be detected during the process.

Our services at a glance

  • Development of individual OCT systems
  • Implementation of individual signal and image processing algorithms
  • System integration
  • Sensor system automation

Fields of application

Contactless diagnostics

OCT has its main field of application in non-contact biomedical diagnostics, such as diagnosis of the fundus of the eye or imaging and differentiation of tissue layers.


Check cell growth

OCT is suitable for quality assurance in tissue manufacturing as it can non-invasively monitor cell growth and inspect defects.


Check paint layers

OCT can be used to measure paint layers in the printing or automotive industry and detect air inclusions.


Process monitoring and control are of central importance for the production and testing of precision components. At Fraunhofer IPT, we develop solutions for direct process monitoring in the laser machine. Our measurement systems based on optical coherence tomography enable component and process monitoring without having to remove the workpiece or influence the actual machining process.


Quality inspection in optics production

OCT is suitable for non-destructively characterizing surfaces of plastic optics and aligning functional surfaces to each other.

Functional extensions of OCT


Full-Field OCT

Full-field OCT (FF-OCT) is a variation of conventional OCT. Here, the sample is illuminated by a microscope objective and the reflected light is recorded and evaluated by an area scan camera.

Polarization sensitive OCT

PS-OCT provides functional information beyond the measurement results of OCT by evaluating individual polarization properties of the samples.