Optical coherence tomography (OCT)

Optical coherence tomography (OCT) was originally developed for in-depth visualization of biological materials. However, thanks to intensive research, it has gained traction in other areas of application outside of medicine.

At Fraunhofer IKTS, OCT is used for the three-dimensional imaging of the most varied material structures, such as ceramics, (glass-fiber-reinforced) plastic, glass or biological materials. OCT enables real-time testing without direct contact with the sample.

The working principle of optical coherence tomography (OCT)

OCT, as a non-invasive, tomographic method, makes it possible to visualize the topography of surfaces and internal structures in scattering media. For this purpose, the studied object is irradiated with wide-band, near-infrared light and the scattered light is processed through a spectrometer. The potential resolution achieved by OCT is between two and 20 µm. OCT is also characterized by its high measuring speed. Volumetric studied areas can be scanned within a few seconds.

Fields of application of optical coherence tomography (OCT)

The Characterization Technologies workgroup offers application-specific OCT studies for the packaging, plastics, electronics, solar and food industries. Furthermore, the researchers develop client-specific OCT test systems for lab operation, product testing and process monitoring.

In the medical context, pharmacological products and various biomaterials are characterized, e.g. from the fields of dermatology, or ear, nose and throat medicine.

Optical coherence tomography (OCT) in additive manufacturing (AM)

The early detection of defects allows to optimize processes and thus save cost. If critical defects occur during the component production, its manufacture is halted. This aspect is of special interest when it comes to the additive manufacturing of ceramic components, as the final processing steps for these materials (drying and sintering) and any rework required are very costly from a financial and technological standpoint.

Fraunhofer IKTS specializes in the development of client-specific OCT systems. The institute has the complete development chain covered – from system design (resolutions, speeds, measuring ranges, illuminating wavelength used), to the development of highly optimized probes, to the development of control, visualization and data processing software. It is also possible to integrate OCT systems developed by IKTS into existing AM printing equipment.

Advantages of optical coherence tomography (OCT)

• Non-invasive, non-contact measurement method
• Resolution in the sub-micrometer range (with light sources of very large spectral width)
• Fast method: more than 30 B-mode images per second
• No sample preparation needed
• Non-ionizing radiation
• Variable measuring range

Services offered for OCT

• Three-dimensional visualization of surfaces and inner structures including analysis
• Static and dynamic coat thickness measurement (coat thicknesses in the µm to mm range)
• Process-oriented feasibility studies (also comparative with other methods)
• Development of universally usable laboratory measuring stations and application-specific test stands
• Spatially resolved speed measurement using Doppler OCT (example: microfluidics)
• On-site demonstrations at the client site

Cooperative research

Cooperative research project with IMM electronics GmbH on the integration of OCT technology in additive manufacturing equipment.