Optical Coherence Measurement Fundamentals for Deep Tooling Cavities
Optical coherence measurement uses broad-bandwidth infrared interference to capture deep cavity topographies without mechanical probe contact or lens clipping.
Polarization Filtering
Meaning
Physical mechanisms isolate specific light wave orientations to reveal internal stresses or remove surface glare during optical inspection. The use of polarization filtering allows quality inspectors to see birefringence patterns in transparent moulded parts. These patterns represent areas of high internal stress caused by the injection process.
It is a standard technique for evaluating the structural integrity of clear components.
Wave Modulation
Light waves usually vibrate in multiple planes as they travel through space. When passed through a polarizer, only the waves vibrating in a single plane are allowed through. Polarization filtering blocks the unwanted light and highlights the phase shifts caused by the material.
This reveals the flow lines and gate stresses that are otherwise invisible.
Stress Visualization
Internal strain changes the way a polymer interacts with polarized light. By employing polarization filtering, a technician can identify areas that are likely to crack or warp under load. This information is used to optimize the hold pressure and cooling time in the moulding cycle.
It provides a quick visual check for part consistency.
Contrast Enhancement
Reflected glare often hides surface defects on shiny plastic parts. Polarization filtering removes these highlights to reveal scratches or sink marks. This improves the reliability of automated vision systems.