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.
Diamond Turned Surface Finish
Meaning
Microscopic surface geometry produced by a single-crystal diamond tool mounted on an ultra-precision lathe, characterized by extremely low roughness and high dimensional accuracy. This technique is used to create the optical-grade surfaces on injection mold inserts for lenses and mirrors. The resulting finish is often smooth enough to be used without subsequent polishing, which preserves the precise geometric form of the cavity.
This process is capable of achieving sub-micron tolerances that are essential for high-performance photonics.
Optical Quality
Accuracy of the light path through a moulded part depends on the lack of scattering from the tool surface. The diamond turned surface finish of a nickel-plated mold insert ensures that the plastic part has a mirror-like appearance and meets the required refractive performance.
Tooling Material
Most molds for diamond turning use electroless nickel plating because it is easier to machine with a diamond tool than hardened steel. This material allows for the creation of complex aspheric shapes that would be impossible to achieve through traditional grinding or hand-polishing methods.
Surface Integrity
Tool marks left by the diamond tip are typically smaller than the wavelength of visible light. Monitoring the wear of the diamond edge is essential to maintain the diamond turned surface finish throughout the fabrication of the mold, as even a small chip in the crystal will leave a visible streak on the final part.