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Advanced optical non-contact surface inspection, "interferometry," never becomes bored, fatigued, distracted, or conditioned to miss defects when they occur.
"Beauty is in the eye of the beholder" can be updated for manufactured products to say that, very often, "quality is in the eye of the consumer."
For many manufactured products, including appliances as well as other consumer goods ranging from automobiles to computers, the slightest "cosmetic" defect can turn a prospective buyer away to purchase an alternative brand. Or it can cause a consumer to return a product for exchange or refund when the defect may or may not have been noticed prior to the purchase.
Defects in sheet metal, composites, or other enclosure materials can be subtle in one kind of lighting, but then show up clearly and annoyingly in the bright directional light of a kitchen, a laundry room, a den or elsewhere. In addition, when and if the bare metal surface is painted or coated with a glossy or shiny coating, defects that were almost invisible on the original bare surface (to the hurried human inspector's eye) become obvious and disturbing to the prospective purchaser.
Reliability Issue
The manual visual inspection of stamped or machined or extruded metal surfaces for subtle and miniature deviations from intended shape is tedious, fatiguing, and, therefore, not reliable. Decades of research show that many defects will be missed by the most dedicated inspector because they occur only occasionally and human nature under pressure is to become conditioned to the defects being absent even when they are not.
Pictured is a small portion of a brushed stainless steel toaster appliance where distortion of the surface shape has occurred. In addition to the small scratch, some local breaks in the curvature of the surface can barely be seen, and even then only because the lighting was adjusted for the photo example in order to enhance its visibility. To ensure consistent high quality appearance of such products, technology is required to rapidly and consistently inspect the surface without tedious or delicate optimization of lighting.
Advanced optical non-contact surface inspection...