US 11,953,686 B2
Combined birefringent material and reflective waveguide for multiple focal planes in a mixed-reality head-mounted display device
Robert Thomas Held, Redmond, WA (US); Bernard Charles Kress, Redmond, WA (US); Ashley Saulsbury, Redmond, WA (US); and Dmitry Reshidko, Redmond, WA (US)
Assigned to MICROSOFT TECHNOLOGY LICENSING, LLC, Redmond, WA (US)
Filed by Microsoft Technology Licensing, LLC, Redmond, WA (US)
Filed on Sep. 26, 2021, as Appl. No. 17/448,890.
Prior Publication US 2023/0103091 A1, Mar. 30, 2023
Int. Cl. G02B 27/01 (2006.01); G02B 27/28 (2006.01); G02F 1/29 (2006.01); G09G 3/00 (2006.01)
CPC G02B 27/0172 (2013.01) [G02B 27/0179 (2013.01); G02B 27/288 (2013.01); G02F 1/294 (2021.01); G09G 3/001 (2013.01); G02B 2027/0127 (2013.01); G02B 2027/0178 (2013.01); G02B 2027/0187 (2013.01)] 18 Claims
OG exemplary drawing
 
1. A method for operating an electronic device that includes a mixed-reality see-through optical display system configured for showing mixed-reality scenes comprising virtual images of virtual-world objects that are rendered over views of real-world objects to a user of the electronic device, the method comprising:
receiving light for the virtual images, the light being linearly polarized in a first polarization state;
operating a ferroelectric liquid crystal (FLC) modulator to switch between the first polarization state for the virtual image light and a second polarization state that is orthogonal to the first polarization state;
providing a lens of birefringent material upon which virtual image light is incident in either the first polarization state or second polarization state, in which the lens provides one of two different focal distances for the virtual images depending on polarization state of the incident virtual image light;
in-coupling the virtual image light from the lens into the mixed-reality see-through optical display system which renders the virtual images at the one of two different focal distances to the user;
stacking combinations of FLC modulators and lenses of birefringent material that act on the received virtual image light in series, in which each combination in a stack of FLC modulators and lenses of birefringent material provides two unique focal distances for the rendered virtual images; and
operating an FLC modulator at a rate that is synchronized to a refresh rate of the received virtual image light to provide a temporally multiplexed virtual image display comprising one or more virtual images located at either one or the other different focal distances or located at both of the different focal distances simultaneously,
wherein the stack of combinations of FLC modulators and lenses of birefringent material are located on the electronic device outside the user's line of sight.