Ultra-high resolution optical coherence tomography for material characterization and quality control

摘要

Optical coherence tomography (OCT), so far mainly used in the biomedical field, has a high potential as non-destructive and contactless technique for material characterization and analysis. For these applications, OCT systems with ultra-high resolution in the micrometer range and capable of high imaging speeds are required. In this work, we combine ultra-high resolution imaging using a femtosecond Ti: sapphire laser as light source with the concepts of transversal OCT. Based on acquisition by heterodyne detection via acousto-optic modulators (AOMs), and by using an xy-galvano scanner unit we are able to obtain en-face scans with sizes as large as 3 x 3 mm~2 within a few seconds. The ultra-high resolution of our OCT system of 2.95 μm axially and 4 μm laterally, both in air, is shown to be essential for imaging of different compounds and fibre materials. We demonstrate the benefits of en-face scanning OCT for various applications in material investigation where in-plane information is of interest which can hardly be obtained by cross-sectional OCT.