Optical coherence tomography for quality assessment of embedded microchannels in alumina ceramic

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. With an optical coherence tomography (OCT) system operating at 1.3 µm and a dedicated automated line segmentation algorithm, layer thicknesses can be measured and laser-machined channels can be verified in alumina ceramics embedded at around 100 µm depth. Monte Carlo simulations are employed to analyze the abilities of OCT in imaging of the embedded channels. The light 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.

Effects of Temperature Variations during Sintering of Metal Ceramic Tooth Prostheses Investigated Non-Destructively with Optical Coherence Tomography

“…Non-invasiveness and high resolution have promoted OCT towards a wide range of applications, such as biomedical diagnosis (in ophthalmology [9][10][11], dermatology [16], dentistry [17][18][19][20], and endoscopy [21]) and non-biomedical testing (of glass, plastic, and semiconductors [22,23], as well as of profiles of metallic surfaces [24]). The advantages, as well as the limitations/complementarities of OCT in relationship to other investigation methods have been reported in respect to imaging teeth [25][26][27] or different types of dental constructs [28][29][30][31][32][33].…”

“…The advantages, as well as the limitations/complementarities of OCT in relationship to other investigation methods have been reported in respect to imaging teeth [25][26][27] or different types of dental constructs [28][29][30][31][32][33]. Relevant to non-destructive testing, targeted here, the impact of the OCT light source, of its central wavelength, as well as of specular reflection, have already been considered [23].…”

Evaluation of Optical Inspection Methods for Non-Destructive Assessment of Embedded Microstructures and Defects in Ceramic Materials

“…Dimensions of the structured channel embedded in highly-scattering alumina ceramic material can also be measured in cross sectional OCT images. [5] As shown in Fig. 3, the measured thickness of the top layer and the depth of the channel are 102μm and 79μm, respectively.…”

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

“…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].…”

“…This results in limited penetration of radiation power and formation of speckles [3,6]. Extremely low signal-to-noise ratio (SNR) in the image domain, which is approaching one [6], is therefore a fact we have to face.…”