Perspectives of mid-infrared optical coherence tomography for inspection and micrometrology of industrial ceramics

Abstract

Optical coherence tomography (OCT) is a promising tool for detecting micro channels, metal prints, defects and delaminations embedded in alumina and zirconia ceramic layers at hundreds of micrometers beneath surfaces. The effect of surface roughness and scattering of probing radiation within sample on OCT inspection is analyzed from the experimental and simulated OCT images of the ceramic samples with varying surface roughnesses and operating wavelengths. By Monte Carlo simulations of the OCT images in the mid-IR the optimal operating wavelength is found to be 4 µm for the alumina samples and 2 µm for the zirconia samples for achieving sufficient probing depth of about 1 mm. The effects of rough surfaces and dispersion on the detection of the embedded boundaries are discussed. Two types of image artefacts are found in OCT images due to multiple reflections between neighboring boundaries and inhomogeneity of refractive index.

Spectral-temporal composition matters when cascading supercontinua into the mid-infrared

“…Together with the high beam quality and intensity of a fiber-delivered beam SCG in chalcogenide fibers has opened the prospects for new powerful MIR analytical tools for broadband fundamental vibrational spectroscopy [6], optical coherence tomography [7], and hyperspectral microscopy [8,9]. Currently, the most mature MIR fiber SC technology is based on fluoride glasses, such as ZrF 4 -BaF 2 -LaF 3 -AlF 3 -NaF (ZBLAN), owing to their high-power capabilities and excellent transmission from the UV to about 4.5 µm [10,11].…”

Tunable optical coherence tomography in the infrared range using visible photons

“…Points indicate the experimental data; solid curves show the cosine fitting of the data according to equation (4). Note that modulation period is given by the wavelength of idler photons.…”

Accurate and automated image segmentation of 3D optical coherence tomography data suffering from low signal-to-noise levels

“…They have a designed depth of 65 μm and widths varying from 140 to 290 μm. These microchannels are covered by a zirconia layer and this geometry mimics a double layer stack with embedded channels [4]. Then they are positioned under the OCT probe to get volumetric data at the imaging sites, 1 and 2, as marked in Fig.…”

“…A potential application of OCT is quality inspection and micrometrology of embedded structures in multilayered ceramic materials [3,4]. This is highly demanded in, e.g., advanced "roll-to-roll" multimaterial-layered 3D shaping technology for manufacturing of multifunctional micro devices with complex 3D structures [5].…”