Systems and methods of assessing a coating microstructure

A method of inspecting a coating on a substrate, the method comprising:

• directing a plurality of electromagnetic pulses towards a scanning location on the coating, each electromagnetic pulse directed from a different rotational position relative to the scanning location, and each electromagnetic pulse directed at an oblique angle relative to a surface of the coating, wherein a first portion of each electromagnetic pulse is reflected from the surface of the coating, and wherein a second portion of each electromagnetic pulse is reflected from a surface of the substrate at an interface between the coating and the substrate;
• determining a time delay between reception of the first portion and the second portion of each reflected electromagnetic pulse at a light detector, thereby defining a plurality of time delays;
• and
• analyzing the plurality of time delays to assess a microstructure of the coating,
• wherein analyzing the plurality of time delays to assess a microstructure of the coating comprises:
• determining a standard deviation value for each of the plurality of time delays associated with each sample;
• grouping the plurality of standard deviation values based on relative differences in the plurality of standard deviation values;
• and assessing the microstructure of the coating of each sample based on the grouping.

A method of assessing a coating microstructure, the method comprising:

• providing a plurality of samples each having a substrate and a coating deposited thereon;
• evaluating each sample with a plurality of electromagnetic pulses that are each directed from a different rotational position relative to each the respective sample;
• obtaining time delay data associated with the plurality of electromagnetic pulses being reflected from the plurality of samples, wherein a time delay is defined by receiving a first portion and a second portion of each electromagnetic pulse reflected from each sample at different points in time;
• and
• assessing a microstructure of the coating on the plurality of samples based on a comparison of the time delay data associated with the plurality of samples,
• wherein assessing the microstructure of the coating on the plurality of samples based on a comparison of the time delay data associated with the plurality of samples comprises:
• determining a standard deviation of the time delay data associated with each sample;
• grouping the standard deviation values based on relative differences in the standard deviation values;
• and
• assessing the microstructure of the coating of each sample based on the grouping.