Laser Focus World Readers - LCPG Technology

Meadowlark Optics’ Liquid Crystal Polarization Gratings utilize spatially varying birefringence to create highly efficient polarization-sensitive gratings. Circularly polarized light can be directed into either the +1 or -1 order depending on the handedness of the incident light. By using a stack of N LCPGs and half-waveplate switches, it is possible to steer to 2^N discrete angles in 1-D or 2-D arrays. Liquid crystal polarization gratings are also known as geometric phase gratings, Pancharatnam-Berry phase gratings, and diffractive waveplates. These transmissive gratings efficiently (> 99.5%) diffract circularly polarized light to either the first positive or negative order, based on the handedness of the incident light. By incorporating fast electro-optic half-wave polarization retarders to control the handedness of polarization, Meadowlark can develop custom LCPG devices and systems with a range of leading capabilities:

• Wide-angle beam steering > 100°
• Large apertures > 20 cm
• Sub-millisecond switching times
• Dramatically reduced size, weight, and power (SWaP) requirements
• Random-access and inertia-less beam steering
• Dynamic focusing also available

Non-Mechanical Steering for a Range of Aperture Sizes

Liquid crystal polarization gratings (LCPGs) are diffractive elements that provide near-100% diffraction for circularly polarized light. When layered with thin polarization-controlling liquid crystal elements, LCPGs provide a means of non-mechanically reconfiguring light into different states, such as for beam steering or focusing. Customers benefit from the patent on the pioneering work with LCPGs in non-mechanical beam steering (US 8,982,313 B2) as well as other related patents.

LCPG Steering for Lidar

LCPG technology excels at non-mechanical beam steering for many narrowband sensors including lidar. To date, we have demonstrated LCPG beam steering for both coherent and direct detection lidars and both monostatic and bistatic architectures. Due to the ability to steer light in discrete steps over large angles, LCPG beam steering is particularly well suited to steering flash lidar systems and coherent doppler lidar wind sensing systems.