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Benefits of LCPG Beam Steering
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Liquid Crystal Polarization Gratings create efficient polarization-sensitive gratings with spatially varying birefringence. Depending on the incident light’s handedness, circularly polarized light experiences either a positive or negative lens effect. By alternating LCPGs and half-waveplate switches, large discrete focus changes can be achieved in less than 40 microseconds.
In microscopy, studying the brain’s 3D neuronal connections poses challenges for traditional laser scanning microscopes, which focus on one depth at a time. Fast focus-changing methods are essential to capture millisecond-scale neuronal dynamics across the millimeter-length scale of connectivity. The use of Liquid Crystal Polarization Grating lenses (LCPG lenses) and controllable liquid crystal switches enables rapid refocusing of more than 500 micrometers in less than 40 microseconds in a multiphoton microscope. Contact a Meadowlark Optics Solutions Engineer for assistance with your unique needs.
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:
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 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.
