Focus modulation optical system and holographic display device having the same

Patent metadata

Field	Value
Publication number	US-11144010-B2
Application number	US-201916287493-A
Country	US
Kind code	B2
Filing date	Feb 27, 2019
Priority date	Aug 10, 2018
Publication date	Oct 12, 2021
Grant date	Oct 12, 2021

Abstract

A focus modulation optical system and a holographic display device having the focus modulation optical system are disclosed. The holographic display device includes a light source configured to emit a plurality of color lights, a focus modulation optical system including at least one variable focus lens that is configured to change a focusing position of incident light by electrical control of the at least one variable focus lens based on a color of light incident on the variable focus lens, and a spatial light modulator configured to form a holographic image by diffracting light output from the focus modulation optical system.

First claim

What is claimed is:

1. A focus modulation optical system comprising:
at least one variable focus lens configured to change a focusing position of incident light by electrical control according to a color such that each color light forms a focus at a same position, the at least one variable focus lens comprising:
a first variable focus lens configured to focus a first color light at a first position;
a second variable focus lens configured to focus a second color light at the first position; and
a third variable focus lens configured to focus a third color light at the first position, wherein the first variable focus lens, the second variable focus lens, and the third variable focus lens are sequentially disposed;

a first wavelength selective retarder provided in front of the first variable focus lens, the first wavelength selective retarder being configured to convert the first color light from a first polarization to a second polarization, and transmit the second color light of the second polarization and the third color light of the second polarization;
a second wavelength selective retarder provided between the first variable focus lens and the second variable focus lens, the second wavelength selective retarder being configured to convert the first color light from the first polarization to the second polarization, convert the second color light from the second polarization to the first polarization, and transmit the third color light of the second polarization; and
a third wavelength selective retarder provided between the second variable focus lens and the third variable focus lens, the third wavelength selective retarder being configured to convert the third color light from the second polarization to the first polarization and transmit the first color light of the second polarization and the second color light of the second polarization, and
wherein each of the first variable focus lens, the second variable focus lens, and the third variable focus lens comprises a first substrate, a first electrode layer provided on the first substrate, a second substrate disposed opposite to the first substrate, a second electrode layer provided on the second substrate, and a liquid crystal layer provided between the first substrate and the second substrate.

2. The focus modulation optical system of claim 1 , wherein
the liquid crystal layer comprises a plurality of active lenses that are configured to change based on a voltage applied between the first electrode layer and the second electrode layer.

3. The focus modulation optical system of claim 2 , wherein at least one of the first electrode layer and the second electrode layer comprises stripe-shape electrodes that are disposed apart from each other.

4. The focus modulation optical system of claim 3 , wherein at least one of an array pitch, a shape, and a curvature of the plurality of active lenses is adjusted based on a voltage applied to the stripe-shape electrodes.

5. The focus modulation optical system of claim 1 , further comprising a fixed focus lens configured to focus light incident on the at least one variable focus lens.

6. The focus modulation optical system of claim 1 , further comprising a wavelength selective retarder provided in front of the at least one variable focus lens, the wavelength selective retarder being configured to selectively delay a phase based on a color of an incident light.

7. A holographic display device comprising:
a light source configured to emit a plurality of color lights;
a focus modulation optical system comprising at least one variable focus lens that is configured to change a focusing position of incident light by electrical control of the at least one variable focus lens based on a color of light incident on the at least one variable focus lens;
a spatial light modulator configured to form a holographic image by diffracting light output from the focus modulation optical system; and
a controller configured to control the light source to time-sequentially emit the plurality of color lights,
wherein the at least one variable focus lens is configured to time-sequentially adjust a focusing position corresponding to the plurality of color lights, and
wherein the at least one variable focus lens comprises:
a first substrate;
a first electrode layer disposed on the first substrate;
a second substrate disposed opposite to the first substrate, a second electrode layer disposed on the second substrate; and
a liquid crystal layer disposed between the first substrate and the second substrate.

8. The holographic display device of claim 7 , wherein
the liquid crystal layer comprises a plurality of active lenses that are configured to change based on a voltage applied between the first electrode layer and the second electrode layer.

9. The holographic display device of claim 8 , wherein at least one of the first electrode layer and the second electrode layer comprises stripe-shape electrodes that are disposed apart from each other.

10. The holographic display device of claim 9 , wherein at least one of an array pitch, a shape, and a curvature of the plurality of active lenses is configured to change based on a voltage applied to the stripe-shape electrodes.

11. The holographic display device of claim 9 , further comprising a fixed focus lens configured to focus light to be emitted on the at least one variable focus lens.

12. The holographic display device of claim 7 , further comprising a wavelength selective retarder provided in front of the at least one variable focus lens and configured to selectively delay a phase based on a color of an incident light.

13. The holographic display device of claim 12 , further comprising a fixed focus lens configured to focus light to be emitted on the wavelength selective retarder.

14. The holographic display device of claim 7 , wherein the at least one variable focus lens comprises:
a first variable focus lens configured to focus first color light at a first position;
a second variable focus lens configured to focus second color light at the first position; and
a third variable focus lens configured to focus third color light at the first position, and
wherein the first variable focus lens, the second variable focus lens, and the third variable focus lens are sequentially disposed.

15. The holographic display device of claim 14 , further comprising:
a first wavelength selective retarder provided in front of the first variable focus lens;
a second wavelength selective retarder provided between the first variable focus lens and the second variable focus lens; and
a third wavelength selective retarder provided between the second variable focus lens and the third variable focus lens.

16. The holographic display device of claim 14 , wherein the controller is further configured to control the first variable focus lens, the second variable focus lens, and third variable focus lens to adjust a focusing position corresponding to each of the first color light, the second color light, and third color light, respectively.

17. The holographic display device of claim 7 , further comprising a beam deflector configured to deflect the plurality of color lights emitted from the light source.

18. The holographic display device of claim 7 , further comprising a position detection sensor configured to detect a position of a viewer viewing the holographic image.

19. A holographic display device comprising:
a light source configured to emit a plurality of color lights;
a beam deflector configured to deflect the pl

Assignees

• Samsung Electronics Co Ltd

Inventors

• Kim Young
• Lee Hongseok
• Song Hoon
• An Jungkwuen
• Won Kanghee
• Choi Chilsung

Classifications

• G03H2001/2271

  RGB holobject · CPC title

• G03H1/2286 Primary

  Particular reconstruction light (G03H1/24 takes precedence); Beam properties · CPC title

• G03H1/2294

  Addressing the hologram to an active spatial light modulator · CPC title

• G03H2223/16

  Optical waveguide, e.g. optical fibre, rod · CPC title

• G03H2222/18

  RGB trichrome light · CPC title