Assessment of optical coherence tomography for metrology applications in high-scattering ceramic materials

Abstract: Large-scale and cost-effective manufacturing of ceramic micro devices based on tape stacking requires the development of inspection systems to perform high-resolution in-process quality control of embedded manufactured cavities, metal structures and defects.In this work, alumina ceramic samples are evaluated by optical coherence tomography (OCT) operating at 1.3?m wavelength and some dimensional data are obtained by dedicated image processing and segmentation. Layer thicknesses can be measured and laser-machined channels can be verified embedded at around 100?m depth. Moreover, detection of internal defects is enabled.Monte Carlo ray tracing simulations are employed to analyze the abilities of OCT in imaging of the embedded channels. The light scattering mechanism is studied for the alumina ceramics, and different scattering origins and models are discussed. The scattering parameters required as input data for simulations are evaluated from the integrating sphere measurements of collimated and diffuse transmittance spectra using a reconstruction algorithm based on refined diffusion approximation approach.