Meaning
Optical measurement systems experience spatial shifts in image position when different wavelengths of light bend at varying angles through refractor optics. A chromatic dispersion error alters the calculated location of surface features by splitting white light into constituent spectral bands that focus at different focal planes. The phenomenon distorts edge definitions and dimensional boundaries in multispectral inspection systems.
Calibration limits this effect within specified focal depths, beyond which chromatic distortion invalidates sub-micron dimensional readings.
Phase Shift
Broad spectrum illumination causes varying focal points along the optical axis, creating color fringes around part edges. Inspection algorithms interpreting these blurred boundaries register false dimensional variations across consecutive manufacturing batches. Validation testing measures spectral displacement across the field of view using certified glass reticles before clearing optical systems for production monitoring.
Supplier claims regarding lens performance often reflect monochromatic conditions rather than broad spectrum factory operations.
Error Consequence
Dimensional measurement drift occurs when uncorrected optics inspect parts under fluctuating factory ambient lighting. A chromatic dispersion error leads to false part rejections during automated quality screening, increasing production scrap costs unnecessarily. Pilot testing on ideal polished samples fails to capture the magnitude of dispersion errors encountered on diffuse production surfaces.
Early signoff on optical capability without broad spectrum validation leads to expensive production halts and sensor recalibrations.
Spectral Shift
Optical filters reduce chromatic distortion by narrowing the wavelength band passing through the imaging lens. Reducing light spectrum width decreases illumination intensity, requiring longer camera exposure times that lower overall inspection throughput.
