Optical CMM Gauge Capability Evaluation for Sub Millimeter Molded Features
Optical CMM capability on sub-millimeter molded features requires material-specific bias correction and telecentric backlighting to maintain GR&R under 20%.
Optical Edge Scatter
Meaning
Light behavior at the physical boundary of a part causes diffraction and reflection that obscures the true location of the edge. High magnification systems often encounter optical edge scatter when inspecting metallic or polished components.
Diffraction Effect
Bending of light waves around a sharp corner creates a fringe pattern that confuses the detection software. This optical edge scatter introduces a small but measurable bias in the dimensional data. Selecting a specific wavelength of light can help reduce the width of these interference patterns.
Signal Distortion
Intensity profiles across a transition appear blurred or noisy due to the interaction of photons with the material edge. When optical edge scatter is present, the software algorithm may select a point that is slightly inside or outside the actual physical boundary. Regular calibration against a known master helps to quantify this offset.
Dimensional Error
Inaccuracy in measurement occurs if the system does not account for the way light interacts with the part geometry. Because optical edge scatter depends on both the material and the shape of the part, the correction factors vary between different product lines. High resolution optics minimize the spread of the scattered light to provide a cleaner signal for analysis.