Industrial OCT

Optical coherence tomography has also been applied to several non-medical applications where accurate surface or thickness measurements are required in a non-invasive non-contact manner [7], [8]. For example, OCT allows for performing non-contact thickness measurements of multilayer coating stacks with a clear differentiation of all layers and their thicknesses. OCT is especially suitable when real-time thickness measurements and monitoring are required, for example, as quality assurance tools in the optical industry. Such profilometry systems can be either time-domain or spectral-domain OCT systems and are comprised of an optical interferometer that is operated with a broadband SLED light source. Typically, long-wavelength time-domain profilometry systems use EXALOS’ high- power and ultra-broadband SLEDs with optical bandwidths of 80 to 100 nm and output powers of 10 to 20 mW (EXS210045 and EXS210046, [2]), corresponding to a coherence length of 9 microns in air. Spectral-domain profilometry systems are using EXALOS’ broadband SLEDs in the 800 to 900-nm wavelength range. Next-generation profilometry systems may also use swept sources with fast scan rates of 100-200 kHz, allowing for even faster and more accurate thickness measurements.