LBTEK quartz multi-order half-wave plates are made from a single piece of quartz crystal, with a thicker construction and simpler fabrication. When a linearly polarized light beam is incident perpendicularly on the waveplate made from uniaxial crystal, it splits into ordinary (o) and extraordinary (e) rays that propagate in the original direction but with perpendicular vibration directions. The corresponding refractive indices are no and ne. Since the two types of light travel at different speeds in the crystal, the phase delay generated after passing through a waveplate of thickness d is given by δ = (2π/λ)|no-ne|d, where |no-ne|d is the optical path difference. The optical path difference generated by a half-wave plate is (2m+1)λ/2, and the phase delay is δ = (2m+1)π, where m is a non-negative integer. For multi-order half-wave plates, m is not equal to 0, and the thickness is determined by the order m.

Compared to zero-order half-wave plates, multi-order half-wave plates introduce an additional phase delay of m full wavelengths, making them more sensitive to wavelength. LBTEK quartz multi-order half-wave plates are commonly used to rotate the polarization direction of linearly polarized light. LBTEK offers both mounted and unmounted multi-order waveplates, with the mounted version featuring a non-removable mechanical housing for convenience. Additionally, LBTEK also offers quartz true zero-order waveplates and quartz zero-order waveplates, which are less affected by wavelength shifts, incident angles, and temperature changes.

LBTEK quartz half-wave plates are commonly used to rotate the polarization direction of linearly polarized light without altering its intensity. Compared to zero-order half-wave plates, multi-order half-wave plates introduce an additional phase delay of m full wavelengths when the light passes through, making them more sensitive to wavelength. The quartz multi-order half-wave plates with installed housings feature non-removable mechanical enclosures. The housing surface is engraved with product model numbers, design wavelengths, and fast axis directions, allowing users to quickly identify and use the waveplate.