Polarization modulator
AssigneeMeta Platforms Technologies, LLC
InventorsHsien-Hui Cheng, Yang Zhao, Hannah Noble, Fenglin Peng, Lu Lu
Life of this patent
Estimating the term…
Abstract
A polarization modulator includes a first liquid crystal cell and a second liquid crystal cell. The first liquid crystal cell has a first type of liquid crystals configured to rotate an optical axis of light parallel to a first plane of the first liquid crystal cell. The second liquid crystal cell is configured to receive the light from the first liquid crystal cell. The second liquid crystal cell has a second type of liquid crystals configured to rotate the optical axis of the light perpendicular to a second plane of the second liquid crystal cell.
Claims19
A polarization modulator comprising:
- a first liquid crystal cell having a first type of liquid crystals configured to rotate an optical axis of light parallel to a first plane of the first liquid crystal cell;
- a second liquid crystal cell configured to receive the light from the first liquid crystal cell, the second liquid crystal cell having a second type of liquid crystals configured to rotate the optical axis of the light perpendicular to a second plane of the second liquid crystal cell;
- and
- a third liquid crystal cell configured to receive the light from the second liquid crystal cell, the third liquid crystal cell having the first type of liquid crystals configured to rotate the optical axis of the light parallel to a third plane of the third liquid crystal cell, and wherein the second liquid crystal cell is disposed between the first liquid crystal cell and the third liquid crystal cell.
A method comprising:
- switching on, for a first time period, a first switchable quarter-waveplate and a second switchable quarter-waveplate;
- switching off a switchable half-waveplate during the first time period, wherein the switchable half-waveplate is disposed between the first switchable quarter-waveplate and the second switchable quarter-waveplate, and wherein light propagating through the first switchable quarter-waveplate, the switchable half-waveplate, and the second switchable quarter-waveplate during the first time period retains a handedness of a circular polarization of the light as the light exits the second switchable quarter-waveplate;
- switching off, for a second time period not overlapping the first time period, the first switchable quarter-waveplate and the second switchable quarter-waveplate;
- and
- switching on the switchable half-waveplate during the second time period, wherein the light propagating through the first switchable quarter-waveplate, the switchable half-waveplate, and the second switchable quarter-waveplate during the second time period changes to an opposite handedness circular polarization as the light exits the second switchable quarter-waveplate.
A head mounted display (HMD) comprising:
- a display configured to emit image light to an eyebox area;
- a polarization rotator configured to modulate the image light between a first circular polarization orientation and a second circular polarization orientation having an opposite handedness as the first circular polarization orientation, wherein the polarization rotator includes:
- a first liquid crystal cell having a first type of liquid crystals configured to rotate an optical axis of the image light parallel to a first plane of the first liquid crystal cell;
- a second liquid crystal cell having a second type of liquid crystals configured to rotate the optical axis of the image light perpendicular to a second plane of the second liquid crystal cell;
- and
- a third liquid crystal cell having the first type of liquid crystals configured to rotate the optical axis of the image light parallel to a third plane of the third liquid crystal cell, wherein the second liquid crystal cell is disposed between the first liquid crystal cell and the third liquid crystal cell.
Dependencies are inferred from the claim text.