Optical Coherence Scanning Measurement Limit Boundaries on Vertical Tooling Cavity Sidewalls
Side-viewing prisms and polarized optical coherence gating extend sidewall slope scanning limits beyond eighty-five degrees in deep tooling cavities.
Rayleigh Length Focus Depth
Meaning
Distance along a laser beam over which the spot size remains within a specified range of its minimum diameter. In the laser welding or marking of plastic parts, this parameter defines the tolerance for variations in the height of the part or the positioning of the tool. A longer focus depth allows for consistent processing even if the moulded surface is slightly warped or if the fixture has a small amount of play.
Process Stability
Control over the energy density at the material surface depends on keeping the beam focused within the correct range. The rayleigh length focus depth of a fiber laser determines how much the part can drift along the optical axis before the weld strength or mark quality begins to degrade.
Beam Geometry
Changing the focal length of the lens alters the relationship between the spot size and the depth of field. A lens that creates a very small spot will have a short rayleigh length focus depth, requiring precise mechanical alignment to maintain the necessary power density for melting the polymer.
Tooling Requirement
Fixtures for large plastic components must be designed to hold the surface within the effective focus zone of the laser. If the part geometry varies more than the rayleigh length focus depth allows, the system must use active height tracking to adjust the focus in real time.