DISPLAYING THREE-DIMENSIONAL OBJECTS

1 .- 271 . (canceled)

272 . An optical device comprising:

a first optically diffractive component comprising a first diffractive structure configured to diffract a first color of light having a first incident angle at a first diffracted angle;

a second optically diffractive component comprising a second diffractive structure configured to diffract a second color of light having a second incident angle at a second diffracted angle;

a first reflective layer configured to totally reflect the first color of light having the first incident angle and transmit the second color of light having the second incident angle; and

a second reflective layer configured to totally reflect the second color of light having the second incident angle,

wherein the first reflective layer is between the first and second diffractive structures, and the second diffractive structure is between the first and second reflective layers.

273 . The optical device of claim 272 , further comprising:

a color-selective polarizer between the first and second diffractive structures,

wherein the first diffractive structure is configured to: i) diffract the first color of light in a first polarization state incident at the first incident angle with a first diffraction efficiency; and ii) diffract the second color of light in a second polarization state incident at the second incident angle with a diffraction efficiency that is substantially smaller than the first diffraction efficiency,

wherein the color-selective polarizer is configured to rotate a polarization state of the second color of light in the second polarization state incident on the color-selective polarizer from the second polarization state to the first polarization state, and

wherein the second diffractive structure is configured to diffract the second color of light in the first polarization state incident at the second incident angle with a second diffraction efficiency.

274 . The optical device of claim 272 , further comprising:

a side surface; and

an optical absorber attached to the side surface and configured to absorb totally reflected light of the first and second colors.

275 . The optical device of claim 272 , wherein the first reflective layer is configured to have a refractive index smaller than that of a layer of the first optically diffractive component that is immediately adjacent to the first reflective layer, such that the first color of light having the first incident angle is totally reflected by an interface between the first reflective layer and the layer of the first optically diffractive component, without totally reflecting the second color of light having the second incident angle.

276 . The optical device of claim 272 , wherein the first optically diffractive component comprises a first carrier film and a first diffraction substrate attached to opposite sides of the first diffractive structure, the first carrier film being closer to the second diffractive structure than the first diffraction substrate, and

wherein the first carrier film comprises the first reflective layer.

277 . The optical device of claim 272 , wherein the second optically diffractive component comprises a second carrier film and a second diffraction substrate attached to opposite sides of the second diffractive structure, the second diffraction substrate being closer to the first diffractive structure than the second carrier film, and

wherein the second reflective layer is attached to the second carrier film.

278 . The optical device of claim 272 , further comprising:

a third optically diffractive component comprising a third diffractive structure configured to diffract first and zero orders of a third color of light incident at a third incident angle on the third diffractive structure, the first order being diffracted at a third diffracted angle, and the zero order being transmitted at the third incident angle,

wherein the second reflective layer is between the second diffractive structure and the third diffractive structure, and

wherein each of the first and second reflective layers is configured to transmit the third color of light incident at the third incident angle.

279 . The optical device of claim 278 , further comprising:

a third reflective layer configured to totally reflect the third color of light incident at the third incident angle on the third reflective layer,

wherein the third diffractive structure is between the second and third reflective layers.

280 . The optical device of claim 278 , wherein the second optically diffractive components comprises a second diffraction substrate and a second carrier film arranged on opposite sides of the second diffractive structure,

wherein the third optically diffractive component comprises a third carrier film and a third diffraction substrate positioned on opposite sides of the third diffractive structure, and

wherein the second reflective layer is between the second and third carrier films.

281 . The optical device of claim 272 , wherein each of the first and second diffractive structure comprises a respective holographic grating formed in a recording medium,

wherein each of the first and second optically diffractive components comprises a respective Bragg grating formed in the recording medium,

wherein the respective Bragg grating comprises a plurality of fringe planes with a fringe tilt angle θ t and a fringe spacing Λ perpendicular to the fringe planes in a volume of the recording medium, and

wherein the respective Bragg grating is configured such that, when an incident angle on the recording medium is an on-Bragg angle, a respective diffracted angle θ m is satisfied with Bragg's equation as below:

mλ= 2 n Λ sin(θ m −θ t ),

where k represents a respective wavelength of a color of light in vacuum,

n represents a refractive index in the recording medium,

θ m represents m th diffraction order Bragg angle in the recording medium,

θ t represents the fringe tilt in the recording medium, and

wherein each of the first and second incident angles is substantially identical to a respective on-Bragg angle, and each of the first and second diffracted angles is substantially identical to a respective first order Bragg angle.

282 . The optical device of claim 281 , wherein a thickness of the recording medium is more than one order of magnitude larger than the fringe spacing.

283 . The optical device of claim 272 , wherein the first diffracted angle and the second diffracted angle are substantially identical to each other, and

wherein each of the first and second diffracted angles is in a range from −10 degree to 10 degree.

284 . The optical device of claim 272 , wherein the first color of light has a wavelength smaller than the second color of light,

wherein the first incident angle of the first color of light is larger than the second incident angle of the second color of light, and

wherein each of the first and second incident angles is in a range from 70 degree to 90 degree.

285 . The optical device of claim 272 , comprising a plurality of components including the first optically diffractive component and the second optically diffractive component,

wherein adjacent two components of the plurality of components are attached together by an intermediate layer that comprises at least one of a refractive index matching material, an OCA, a UV-cured or heat-cured optical glue, or an optical contacting material.

286 . The optical device of claim 285 , wherein the second reflective layer comprises a corresponding intermediate layer.

287 . The optical device of claim 272 , further comprising a substrate having a back surface attached to a front surface of the first optically diffractive component.

288 . The optical device of claim 287 , wherein the substrate comprises a side surface angled to the back surface and is configured to receive a plurality of different colors of light at the side surface, wherein an angle between the side surface and the back surface of the substrate is no less than 90 degree, and wherein the substrate is configured such that the plurality of different colors of light are incident on the side surface with an incident angle substantially identical to 0 degree.

289 . The optical device of claim 287 , wherein the substrate is wedged and comprises a titled front surface, and wherein an angle between the front surface and the side surface is less than 90 degree.

290 . An optical device, comprising:

at least two optically diffractive components; and

at least one reflective layer,

wherein the optical device is configured such that, when light of different colors is incident on the optical device, the optical device separates light of individual colors of the different colors while suppressing crosstalk between the different colors, and

wherein the at least one reflective layer is configured for total internal reflection of light of at least one of the different colors.

291 . The optical device of claim 290 , wherein the optical device is configured such that an output light beam diffracted by the optical device comprises only light of a particular color of the different colors without crosstalk from one or more other colors of the different colors.

292 . The optical device of claim 290 , wherein the at least one reflective layer is configured to totally reflect zero order light of a particular color of the different colors transmitted by a respective one of the optically diffractive component, while transmitting one or more other colors of the different colors

293 . The optical device of claim 290 , wherein the optical device is configured such that, when the light of different colors is incident on the optical device, each of the optically diffractive components diffracts light of a respective color of the different colors.

294 . The optical device of claim 290 , wherein the optically diffractive components comprise at least one of one or more transmissive diffractive structures or one or more reflective diffractive structures, and

wherein each of the at least one of the one or more transmissive diffractive structures or the one or more reflective diffractive structures is configured to light of a respective color of the different colors.

295 . The optical device of claim 290 , further comprising:

at least one color-selective polarizer configured to rotate a polarization state of light of at least one color of the different colors, such that light of a particular color of the different colors is incident in a first polarization state on a respective one of the optically diffractive components, while light of one or more other colors of the different colors is incident in a second polarization state different from the first polarization state on the respective one of the optically diffractive components.

296 . An optical device comprising:

a first optically diffractive component comprising a first diffractive structure configured to: i) diffract first and zero orders of a first color of light incident at a first incident angle on the first diffractive structure, the first order being diffracted at a first diffracted angle, and the zero order being transmitted at the first incident angle; and ii) transmit a second color of light incident at a second incident angle on the first diffractive structure;

a first reflective layer configured to: i) totally reflect the first color of light incident on the first reflective layer at the first incident angle; and ii) transmit the second color of light incident on the first reflective layer at the second incident angle;

a second optically diffractive component comprising a second diffractive structure configured to diffract first and zero orders of the second color of light incident at the second incident angle on the second diffractive structure, the first order being diffracted at a second diffracted angle, and the zero order being transmitted at the second incident angle; and

a second reflective layer configured to totally reflect the second color of light incident on the second reflective layer at the second incident angle,

wherein the first reflective layer is between the first and second diffractive structures, and the second diffractive structure is between the first and second reflective layers.

297 . A method comprising:

transmitting at least one timing control signal to an illuminator to activate the illuminator to emit a plurality of different colors of light onto an optical device, such that the optical device converts the plurality of different colors of light to individually diffracted colors of light to illuminate a display comprising a plurality of display elements; and

transmitting, for each of the plurality of display elements of the display, at least one respective control signal to modulate the display element, such that the individually diffracted colors of light are reflected by the modulated display elements to form a multi-color three-dimensional light field corresponding to the respective control signals,

wherein the optical device comprises:

a first optically diffractive component comprising a first diffractive structure;

a second optically diffractive component comprising a second diffractive structure;

a first reflective layer; and

a second reflective layer,

wherein:

the first reflective layer is between the first and second diffractive structures;

the second diffractive structure is between the first and second reflective layers;

when a first color of light is incident at a first incident angle on the first diffractive structure, the first diffraction structure diffracts first and zero orders of the first color, the first order being diffracted at a first diffracted angle, and the zero order being transmitted at the first incident angle;

when a second color of light is incident at a second incident angle on the first diffractive structure, the first diffraction grating transmits the second color of light at the second incident angle;

when the first color of light is incident on the first reflective layer at the first incident angle, the first reflective layer totally reflects the first color of light;

when the second color of light is incident on the first reflective layer at the second incident angle, the reflective layer transmits the second color of light at the second incident angle;

when the second color of light is incident at the second incident angle on the second diffractive structure, the second diffractive structure diffracts first and zero orders of the second color of light, the first order being diffracted at a second diffracted angle, and the zero order being transmitted at the second incident angle; and

when the second color of light is incident on the second reflective layer at the second incident angle, the second reflective layer totally reflects the second color of light.

298 . The optical device of claim 297 , further comprising:

obtaining graphic data comprising respective primitive data for a plurality of primitives corresponding to an object in a three-dimensional space;

determining, for each of the plurality of primitives, an electromagnetic (EM) field contribution to each of the plurality of display elements of the display by calculating, in a three-dimensional coordinate system, an EM field propagation from the primitive to the display element;

generating, for each of the plurality of display elements, a sum of the EM field contributions from the plurality of primitives to the display element; and

generating, for each of the plurality of display elements, the respective control signal based on the sum of the EM field contributions to the display element for modulation of at least one property of the display element,

wherein the multi-color three-dimensional light field corresponds to the object.

299 . The optical device of claim 298 , comprising:

sequentially modulating the display with information associated with the plurality of different colors in a series of time periods, and

controlling the illuminator to sequentially emit each of the plurality of different colors of light to the optical device during a respective time period of the series of time periods, such that each of the plurality of different colors of light is diffracted by the optical device to the display and reflected by the modulated display elements of the display to form a respective color three-dimensional light field corresponding to the object during the respective time period.

300 . The optical device of claim 297 , wherein the plurality of different colors of light are diffracted by the optical device at a substantially same diffracted angle to the display, and

wherein the diffracted angle is within a range from −10 degree to 10 degree.

301 . The optical device of claim 297 , wherein the illuminator and the optical device are configured such that the plurality of different colors of light are incident on the first optically diffractive component of the optical device with respective incident angles, and

wherein each of the respective incident angles is in a range from 70 degree to 90 degree.