Optical inspection of waterjet drilled holes

A method of inspecting erosion of a coating on a component at an outlet of a through-hole formed by waterjet drilling, the method comprising:

• positioning a camera to face the outlet;
• positioning a light source at a first position from an inlet opposite the outlet of the through-hole;
• capturing a first image data of the outlet and surrounding coating with the camera while the light source is at the first position;
• positioning the light source at a second position from the inlet, wherein the first position is located between the inlet and the second position;
• capturing a second image data of the outlet and surrounding coating with the camera while the light source is at the second position;
• and
• determining an amount of erosion of the coating at the outlet by comparing the first image data to the second image data by identifying an outermost edge of the outlet at an outlet surface of the coating and by measuring, parallel to the outlet surface, a maximum distance of erosion from an innermost edge of a sidewall of the through-hole to the outermost edge of the outlet.