AFB® of zero-order compound waveplate with high accuracy and precision retardation values

Onyx Optics has developed an adhesive-free-bond (AFB^®) process that produces highly precise and accurate retardation zero-order compound waveplates. The developed process leverages the epoxy bonded and the air-gaped counterparts by its production of lower optical loss waveplates. We have implemented a thickness monitoring system that can measure the retardation thickness of the waveplate in process. We can then adjust the process parameters accordingly to attain the target thickness of the waveplate. The process achieves thickness control of zero-order waveplates within ±0.2μm and retardation within ±1.0°. The AFB^® process can be applied to various birefringent/isotropic crystal combinations such as α-quartz/fused silica, MgF₂/fused silica, sapphire/YAG, and MgF₂ of different orientations. We have developed a modeling tool that considers the beam wavelength, retardation, and fast axis orientation of each compound waveplate layer as the independent variables and returns the analytical solution that displays a series of polarization phase maps of the transmitting beam before and after passing through each layer of multilayered compound waveplate stacks. The modeling tool also simulates the polarization states with the given parameters uncertainties and allows subsequent cross variables correction for attaining target polarization state with fabrication flexibility and efficacy.