Freeform varifocal optical assembly

Abstract

A freeform varifocal optical assembly includes at least three optical modules including a first plurality of polarization sensitive optical elements including Pancharatnam-Berry phase (PBP) lenses, polarization sensitive hologram (PSH) lenses, metamaterials, or combinations thereof. The plurality of polarization sensitive optical elements of each optical module include a property associated with a Zernike polynomial. Each of the first and the three optical modules are configurable between a plurality of optical powers. The freeform varifocal optical assembly is configurable to output a predetermined wavefront in response to an input wavefront.

What is claimed is: 
     
         1 . A freeform varifocal lens comprising:
 at least three optical modules, each optical module comprising a corresponding plurality of polarization sensitive optical elements, wherein each optical module is associated with a corresponding Zernike polynomial, wherein for each optical module, the corresponding plurality of polarization sensitive optical elements comprises a corresponding property associated with the corresponding Zernike polynomial, and wherein the corresponding Zernike polynomial associated with each optical module is different,   wherein one or more optical stages in each optical module comprises a switchable optical retarder and a polarization sensitive optical element comprising a Pancharatnam-Berry phase (PBP) lens or a polarization sensitive hologram (PSH) lens, wherein the switchable optical retarder is configured to transmissively convert light of a first polarization or a second polarization into light of the second polarization or the first polarization, respectively, and   wherein each optical stage comprises at least one polarization sensitive optical element, and wherein at least some of the polarization sensitive optical elements within each optical module have different optical powers.   
     
     
         2 . The freeform varifocal lens of  claim 1 , wherein the corresponding plurality of polarization sensitive optical elements comprise Pancharatnam-Berry phase (PBP) lenses, polarization sensitive hologram (PSH) lenses, metamaterials, or combinations thereof. 
     
     
         3 . The freeform varifocal lens of  claim 1 ,
 wherein the switchable optical retarder is configurable to be in an “off” state or an “on” state,   wherein:
 in the “off” state, the switchable optical retarder is configured to convert light of the first or the second polarization into light of the second polarization or light of the first polarization, respectively; and 
 in the “on” state, the switchable optical retarder transmits light without changing its polarization, and 
   wherein the polarization sensitive optical element comprising the PBP lens or the PSH lens is configured to receive light transmitted through the switchable optical retarder and has an optical power that is dependent on whether the light transmitted through the switchable optical retarder has the first polarization or the second polarization.   
     
     
         4 . The freeform varifocal lens of  claim 1 , wherein the switchable optical retarder comprises a switchable half wave plate. 
     
     
         5 . The freeform varifocal lens of  claim 1 , wherein each optical module is configured to provide a wavefront adjustment associated with the corresponding Zernike polynomial to an incident wavefront. 
     
     
         6 . The freeform varifocal lens of  claim 1 , wherein the at least three optical modules are configured to output a variable wavefront based on different combinations of respective wavefront adjustments. 
     
     
         7 . The freeform varifocal lens of  claim 1 , wherein each polarization sensitive optical element of the corresponding plurality of polarization sensitive optical elements comprises a PBP lens and wherein the property comprises a liquid crystal director pattern. 
     
     
         8 . The freeform varifocal lens of  claim 1 , further comprising at least one of a circular polarizer or a linear polarizer. 
     
     
         9 . The freeform varifocal lens of  claim 1 , wherein a corresponding Zernike polynomial of a first optical module of the at least three optical modules is associated with tilt in a first direction, a corresponding Zernike polynomial of a second optical module of the at least three optical modules is associated with tilt in a second direction, a corresponding Zernike polynomial of a third optical module of the at least three optical modules is associated with focus, a corresponding Zernike polynomial of a fourth optical module of the at least three optical modules is associated with oblique astigmatism, and a corresponding Zernike polynomial of a fifth optical module of the at least three optical modules is associated with vertical astigmatism. 
     
     
         10 . The freeform varifocal lens of  claim 1 , wherein at least one optical module of the at least three optical modules is associated with trefoil, coma, quadrafoil, or secondary astigmatism. 
     
     
         11 . A display comprising:
 a light source configured to emit image light; and   a freeform varifocal optical assembly configured to guide the image light to an eyebox of the optical device, the freeform varifocal optical assembly comprising:
 at least three optical modules, each optical module comprising a corresponding plurality of polarization sensitive optical elements, wherein each optical module is associated with a corresponding Zernike polynomial, wherein, for each optical module, the corresponding plurality of polarization sensitive optical elements comprises a corresponding property associated with the corresponding Zernike polynomial, and wherein the corresponding Zernike polynomial associated with each optical module is different, 
 wherein one or more optical stages in each optical module comprises a switchable optical retarder and a polarization sensitive optical element comprising a Pancharatnam-Berry phase (PBP) lens or a polarization sensitive hologram (PSH) lens, wherein the switchable optical retarder is configured to transmissively convert light of a first polarization or a second polarization into light of the second polarization or the first polarization, respectively, and 
 wherein each optical stage comprises at least one polarization sensitive optical element, and wherein at least some of the polarization sensitive optical elements within each optical module have different optical powers. 
   
     
     
         12 . The display of  claim 11 , wherein the corresponding plurality of polarization sensitive optical elements comprise Pancharatnam-Berry phase (PBP) lenses, polarization sensitive hologram (PSH) lenses, metamaterials, or combinations thereof. 
     
     
         13 . The display of  claim 11 ,
 wherein the switchable optical retarder is configurable to be in an “off” state or an “on” state,   wherein:
 in the “off” state, the switchable optical retarder is configured to convert light of a first or a second polarization into light of the second polarization or light of the first polarization, respectively; and 
 in the “on” state, the switchable optical retarder transmits incident light without changing its polarization, and 
   wherein the polarization sensitive optical element comprising the PBP lens or the PSH lens is configured to receive light transmitted through the switchable optical retarder and has an optical power that is dependent on whether the light transmitted through switchable optical retarder has the first polarization or the second polarization.   
     
     
         14 . The display of  claim 11 , wherein the switchable optical retarder comprises a switchable half wave plate. 
     
     
         15 . The display of  claim 11 , wherein each optical module is configured to provide a wavefront adjustment associated with the corresponding Zernike polynomial to an incident wavefront. 
     
     
         16 . The display of  claim 11 , wherein the at least three optical modules are configured to output a variable wavefront based on different combinations of respective wavefront adjustments. 
     
     
         17 . The display of  claim 11 , wherein the freeform optical assembly is configured to steer an exit pupil of the head mounted display, and wherein the freeform optical assembly is further configured to compensate for aberrations of the exit pupil of the head mounted display. 
     
     
         18 . The display of  claim 11 , wherein the display comprises a head mounted display. 
     
     
         19 . A method comprising:
 transmitting light through at least three optical modules, wherein each optical module comprises a plurality of polarization sensitive optical elements, wherein each optical module is associated with a corresponding Zernike polynomial, wherein for each optical module, the corresponding plurality of polarization sensitive optical elements comprises a corresponding property associated with the corresponding Zernike polynomial, wherein the corresponding Zernike polynomial associated with each optical module is different,   wherein one or more optical stages in each optical module comprises a switchable optical retarder and a polarization sensitive optical element comprising a Pancharatnam-Berry phase (PBP) lens or a polarization sensitive hologram (PSH) lens, wherein each optical stage comprises at least one polarization sensitive optical element, and wherein at least some of the polarization sensitive optical elements within each optical module have different optical powers; and   adjusting the focal power of one or more of the at least three optical modules by changing respective states of one or more polarization sensitive optical elements of the plurality of polarization sensitive optical elements in the one or more of the at least three optical modules.   
     
     
         20 . The method of  claim 19 ,
 wherein the switchable optical retarder is configurable to be in an “off” state or an “on” state,   wherein:
 in the “off” state, the switchable optical retarder is configured to convert light of a first or a second polarization into light of the second polarization or light of the first polarization, respectively; and 
 in the “on” state, the switchable optical retarder transmits incident light without changing its polarization; 
   wherein the polarization sensitive optical element comprising the PBP lens or the PSH lens is configured to receive light transmitted through the switchable optical retarder and has an optical power that is dependent on whether the light transmitted through the polarization sensitive optical element of the first type has the first polarization or the second polarization; and   adjusting the focal power comprises controlling the state of the switchable optical retarders.