Constant Magnification Boundary
Precision optical inspection systems require specialized optical lenses that eliminate dimensional magnification changes caused by object height variations. Telecentric lens limits define the physical entrance pupil boundaries, field of view dimensions, working distances and depth of field constraints within which a telecentric optical lens maintains constant magnification. They determine the maximum height variance and object footprint size an automated optical inspection system can measure accurately without optical distortion.
These limits govern visual inspection systems used for surface mount assemblies and silicon substrates.
Perspective Error Elimination
Standard optical lenses exhibit perspective error, making object dimensions appear larger when closer to the camera lens and smaller when farther away. In electronic inspection, perspective error distorts component leads and solder joint height readings, leading to false measurement results. Operating within telecentric lens limits ensures that light rays enter the lens parallel to the optical axis, preserving accurate scale across varying component heights.
Pushing inspection targets beyond these design limits introduces optical vignetting and wavefront aberration, degrading measurement accuracy along target edges.
Field Measurement Capability
Mechanical calibration targets verify optical field size and telecentricity across the complete inspection volume. Telecentric lens limits restrict maximum panel scanning width per camera pass, dictating the step-and-repeat positioning required for large circuit board inspection.
