LCPG Principles
Download PDF Fundamentals Liquid crystal polarization gratings (PGs) are fascinating
Non-mechanically reconfigurable optics with vastly superior size, weight, and power requirements compared to their mechanical counterparts
The use of LCPGs in nonmechanical beam steering is a novel technique, and Meadowlark has the patent on this approach (US 8,982,313 B2).
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 2N 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:
Dynamic focusing is also available.
Meadowlark can build LCPGs and LC switches using thin 200 μm glass and with apertures ranging from 2 mm to 200 mm. Thin glass enables discrete steering to >1,000 revolvable angles with transmissive assemblies < 1 cm thick. Meanwhile the ability to steer large beams over large angles makes this approach unique among non-mechanical steering technologies for replacing large gimbals or steering large collection apertures in optical receiver paths.
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.
Meadowlark can provide custom systems to meet your needs using the patented liquid crystal polarization grating (LCPG) beam steering technology. When contacting us for a quote, please provide: | •Clear Aperture (mm) •Operating Wavelength (nm) •1D or 2D Steering •Number of Angles •Maximum Steering Angle (°) •Response Time/Switching Speed (ms) •Housing/Mechanical Interface Requirements •Description of Application & Additional Details |
Variable Retarders
Liquid Crystal Variable Retarder
UV Variable Retarder
MWIR Variable Retarder
OEM LCVR
Rotators
Achromatic High-Speed Rotator
Binary Rotator
Polarization Rotator
Shutters / Attenuators
Achromatic High-Speed Shutter
High Contrast Shutter
Variable Attenuator
Controllers
Analog Controller
FLC Controller
LC Digital Interface Controller
Temperature Controller
Most of the commercial interest in Liquid Crystal Polarization Gratings has been for non-mechanical beam steering and so that is the current focus of this document. Please inquire directly regarding LCPG tunable lens assemblies and individual LCPG and LCP lens components.
Download PDF Fundamentals Liquid crystal polarization gratings (PGs) are fascinating
Geometric-phase microscopy (GPM) uses changes in the phase of light