Meaning
Optical phenomenon descriptions refer to the artifact where the recorded intensity profile of an interference fringe exceeds its true maximum value. Fringe peak overshoot occurs in interferometry systems when high-frequency signal noise or digital filtering errors distort the measurement of surface heights. This distortion can lead to incorrect calculations of surface roughness and planarity.
Signal Distortion
Optical sensors must process alternating light and dark bands to reconstruct the surface profile of a sample. When fringe peak overshoot occurs, the reconstruction algorithm interprets the exaggerated intensity peaks as physical high points on the surface. This misinterpretation creates artificial spikes in the digital model of the part.
Metrology Error
Automated inspection routines can fail if the measurement system registers height deviations that do not exist. This issue occurs when the digital filters used to smooth the signal are poorly tuned. Adjusting the filter coefficients is necessary to ensure that the reconstructed profile matches the actual physical geometry.
Quality Impact
Process controls rely on accurate surface measurements to approve high-precision optical or silicon components. False rejections of good parts or acceptance of bad parts can occur if the measurement system is compromised by this optical artifact. Using robust filtering algorithms prevents these errors and maintains the integrity of the quality control process.
