The probes measure 0.1 in. long with a 0.05-in. diameter and contain other features with 0.10-mil tolerances. Probe maker R&D Tool Specialists in Santa Clara uses a machine-vision system from TechniQuip in Livermore, Calif., to inspect finished probes.

"Some small parts can be measured using a micrometer or caliper-type gages," says Tom Ross, president of R&D Tool Specialist. "Such methods don't work well on these probes because they're so small and complex. We also had an optical microscope with a measuring eyepiece that might have been able to resolve many of the tiny part features. But its measurements rely heavily on operator interpretation and they're not re-producible or objectively verifiable."

The TechniQuip system is built around standard PC hardware and software. A stencil mode permits compares key dimensions on a part against a known good part or "golden master." A pattern-recognition algorithm automatically rotates and aligns images of parts oriented randomly within the field of view. This eliminates the need for a fixture to hold samples.