LBTEK Fused Silica Optical Contact True Zero-Order Half-Wave Plate is commonly used to rotate the Polarization Direction of Linearly Polarized Light. After Linearly Polarized Light passes through the True Zero-Order Half-Wave Plate, the resulting Optical Path Difference (OPD) is λ/2, and the Phase retardance is π. The Design Wavelengths of the Fused Silica Optical Contact True Zero-Order Wave Plate include common wavelengths used in fields such as laser cooling, atomic clocks, and quantum precision measurement: 399 nm, 509 nm, 556 nm, 671 nm, 780 nm, 795 nm, 813 nm, 852 nm, and 1013 nm. For the Fused Silica Optical Contact True Zero-Order Half-Wave Plate with a Retaining Ring housing, the housing is non-removable, and the Item # and the Wave Plate Fast Axis Marking line are engraved on the housing surface, making it easy for customers to identify and use. Each Fused Silica Optical Contact True Zero-Order Half-Wave Plate is shipped with a one-to-one quality inspection report, which records the actual measured specifications of the wave plate (including key parameters such as Retardance and wavefront difference), ensuring full traceability of product quality.