Chapter Optical Coherence Tomography – Applications in Non- Destructive Testing and Evaluation

Optimizatio

Terahertz Time-Domain Polarimetry in Reflection for Film Characterization

Terahertz time-domain spectroscopy is a useful technique to characterize layered samples and thin films. It gives access to their optical properties and thickness. Such measurements are done in transmission, which requires access to the sample from opposite sides. In reality this is not always possible. In such cases, reflection measurements are the only option, but they are more difficult to implement. Here we propose a method to characterize films in reflection geometry using a polarimetric approach based on the identification of Brewster angle and modeling of the measured signal to extract the refractive index and thickness of the sample. The technique is demonstrated experimentally on an unsupported single layer thin film sample. The extracted optical properties and thickness were in good agreement with established transmission terahertz spectroscopy measurements. The new method has the potential to cover a wide range of applications, both for research and industrial purposes

Chapter Optical Coherence Tomography – Applications in Non- Destructive Testing and Evaluation

Optimizatio

Characterization of medical and biological samples with a Talbot–Lau grating interferometer μXCT in comparison to reference methods

Talbot–Lau grating interferometry is a new innovative X-ray technology in the field of radiography and computed tomography that extends the imaging capabilities of absorption contrast (AC) in medicine and material science by the introduction of differential phase contrast (DPC) and dark-field contrast (DFC). This paper discusses the benefits of the additional imaging modality of DFC provided by a new desktop Talbot–Lau μXCT system (SkyScan 1294). With this system, selected medical and biological samples such as medical foam, cortical bone, molar tooth, and barley corn seed samples have been imaged and compared to reference methods such as high-resolution μXCT and optical coherence tomography (OCT) regarding information gain and contrast

In-Situ Optical Coherence Tomography (OCT) for the Time-Resolved Investigation of Crystallization Processes in Polymers

By application of optical coherence tomography (OCT), an interferometric noncontact imaging technique, the crystallization of a supercooled poly­(propylene) melt in a slit die is monitored. Both the quiescent and the sheared melt are investigated, with a focus on experiments where solidification and flow occur simultaneously. OCT is found to be an excellent tool for that purpose since the resultant structures are strongly scattering, which is a prerequisite for application of that method. The resulting images enable for the first time to directly monitor structure development throughout the whole experiment, including final cooling to room temperature. By rendering the setup polarization-sensitive, information on the birefringence of the pertinent structures is obtained

Supplement 1: Super-resolution photoacoustic microscopy using blind structured illumination

Algorithm and Supporting Data Originally published in Optica on 20 January 2017 (optica-4-1-17