Measuring Hole Depth and Concentricity

Measuring hole depth using depth-from-focus techniques.

A customer asked us to measure the depth, diameter and concentricity of a drilled hole in a small metal part. We built a demonstration to do it:

• A camera on a motion stage, triggered on the fly every 10µm as it moves through focus
• The sharpest image in that sequence is picked out, and its diameter measured and recorded
• Repeated at the top and bottom of the hole, giving depth, diameter and concentricity

We ran an extended test on customer-supplied samples as a pseudo Gauge R&R study, and reported back on the system's capability. We regularly run tests like this for customer applications — contact us with yours.