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 Focus Algorithms
Meaning
Mathematical procedures analyze image contrast and sharpness to determine the optimal lens position for capturing clear images. Utilizing optical focus algorithms allows automated microscopes and inspection cameras to adjust their focus automatically and rapidly during high volume production runs. This automated adjustment is essential when inspecting parts of varying heights on a moving conveyor belt.
Analysis Method
Measuring the high frequency content of an image’s pixel intensity distribution provides a quantitative score of image sharpness. When implementing optical focus algorithms, the software searches for the lens position that produces the highest sharpness score. This peak corresponds to the plane of optimal focus for the inspected feature.
Autofocus Execution
Controlling the motor driven lens stage requires feedback loops that move the lens quickly to the calculated focal point. Applying fast optical focus algorithms reduces the time spent on image capture, which directly increases the overall throughput of the inspection system. This speed is critical in high speed electronic assembly.
System Limit
Low contrast surfaces or uneven lighting can confuse the sharpness calculations and lead to focus errors. When the surface of the inspected part is highly reflective or lacks texture, the optical focus algorithms struggle to find a reliable peak. To overcome this limitation, systems often project a structured light pattern onto the target to create temporary contrast.
This addition ensures that the focus mechanism remains stable across different part materials and finishes.