Holographic display device having reduced chromatic aberration

Patent metadata

Field	Value
Publication number	US-11774752-B2
Application number	US-202017107290-A
Country	US
Kind code	B2
Filing date	Nov 30, 2020
Priority date	Jul 4, 2018
Publication date	Oct 3, 2023
Grant date	Oct 3, 2023

Abstract

A holographic display device includes a light source configured to emit light, the light including first light of a first wavelength, second light of a second wavelength, and third light of a third wavelength; a spatial light modulator configured to form a holographic pattern to modulate the light emitted from the light source and to produce a holographic image; and a focusing optical system configured to focus the holographic image. The focusing optical system includes a fixed-focus optical system having a fixed focal length, and a variable focus optical system having a focal length that is changed by electrical control. The fixed-focus optical system is configured to focus the first light of the first wavelength, the second light of the second wavelength, and the third light of the third wavelength on different positions, respectively, on an optical axis to cancel a chromatic aberration by the variable focus optical system.

First claim

What is claimed is:

1. A focusing optical system comprises:
a fixed-focus optical system having a fixed focal length on an optical axis; and
a variable focus optical system having a focal length that is changed by electrical control,
wherein the fixed-focus optical system is configured to focus first light of a first wavelength, second light of a second wavelength different from the first wavelength, and third light of a third wavelength different from the first wavelength and the second wavelength on different positions, respectively, on the optical axis to cancel chromatic aberration by the variable focus optical system, and
wherein the fixed-focus optical system comprises:
a first lens set configured to focus the first light on a first position on the optical axis, the first lens set comprising a first wavelength-selective polarization conversion element and a first anisotropic diffractive lens element;
a second lens set configured to focus the second light on a second position on the optical axis that is different from the first position, the second lens set comprising a second wavelength-selective polarization conversion element and a second anisotropic diffractive lens element; and
a third lens set configured to focus the third light on a third position on the optical axis that is different from the first position and the second position, the third lens set comprising a third wavelength-selective polarization conversion element and a third anisotropic diffractive lens element.

2. The focusing optical system of claim 1 , wherein each of the fixed-focus optical system and the variable focus optical system has a positive refractive power.

3. The focusing optical system of claim 2 , wherein a distance between the variable focus optical system and the first position is less than a distance between the variable focus optical system and the second position,
the distance between the variable focus optical system and the second position is less than a distance between the variable focus optical system and the third position,
the third wavelength is longer than the second wavelength, and
the second wavelength is longer than the first wavelength.

4. The focusing optical system of claim 2 , wherein a distance between the variable focus optical system and the first lens set is less than a distance between the variable focus optical system and the second lens set, and
the distance between the variable focus optical system and the second lens set is less than a distance between the variable focus optical system and the third lens set.

5. The focusing optical system of claim 2 , wherein the variable focus optical system comprises a variable focus diffractive lens element having a first focal length for the first light, a second focal length for the second light, and a third focal length for the third light,
the first focal length is longer than the second focal length, and
the second focal length is longer than the third focal length.

6. The focusing optical system of claim 5 , wherein the first position, the second position, and the third position are respectively selected to cancel chromatic aberration by the variable focus diffractive lens element to be within a focus adjustment range of the variable focus diffractive lens element.

7. The focusing optical system of claim 5 , wherein a distance between the first position and the second position is equal to a difference between the first focal length and the second focal length, and
a distance between the second position and the third position is equal to a difference between the second focal length and the third focal length.

8. The focusing optical system of claim 2 , wherein the first wavelength-selective polarization conversion element, the first anisotropic diffractive lens element, the second wavelength-selective polarization conversion element, the second anisotropic diffractive lens element, the third wavelength-selective polarization conversion element, and the third anisotropic diffractive lens element are sequentially arranged along the optical axis.

9. The focusing optical system of claim 2 , wherein the first wavelength-selective polarization conversion element is configured to polarize the first light to have a first linear polarization component and polarize the second light and the third light to have a second linear polarization component that is orthogonal to the first linear polarization component,
the second wavelength-selective polarization conversion element is configured to polarize the second light to have the first linear polarization component and the first light and the third light to have the second linear polarization component, and
the third wavelength-selective polarization conversion element is configured to polarize the third light to have the first linear polarization component and the first light and the second light to have the second linear polarization component.

10. The focusing optical system of claim 9 , wherein each of the first anisotropic diffractive lens element, the second anisotropic diffractive lens element, and the third anisotropic diffractive lens element is configured to focus light of the first linear polarization component and transmit light of the second linear polarization component without diffraction.

11. The focusing optical system of claim 9 , wherein the fixed-focus optical system further comprises a fourth wavelength-selective polarization conversion element configured to polarize the first light, the second light and the third light to have a same linear polarization component.

12. The focusing optical system of claim 2 , wherein the first wavelength-selective polarization conversion element is configured to polarize the first light to have a first circular polarization component and to polarize the second light and the third light to have a second circular polarization component that is opposite to the first circular polarization component,
the second wavelength-selective polarization conversion element is configured to polarize the second light to have the first circular polarization component and the first light and the third light to have the second circular polarization component, and
the third wavelength-selective polarization conversion element is configured to polarize the third light to have the first circular polarization component and the first light and the second light to have the second circular polarization component.

13. The focusing optical system of claim 12 , wherein each of the first anisotropic diffractive lens element, the second anisotropic diffractive lens element, and the third anisotropic diffractive lens element is configured to focus light of the first circular polarization component and transmit light of the second circular polarization component without diffraction.

14. The focusing optical system of claim 12 , wherein the fixed-focus optical system further comprises a fourth wavelength-selective polarization conversion element configured to polarize the first light, the second light, and the third light to have a same circular polarization component.

15. The focusing optical system of claim 1 , wherein the fixed-focus optical system has a positive refractive power and the variable focus optical system has a negative refractive power.

16. The focusing optical system of claim 15 , wherein the fixed-focus optical system comprises a fixed-focus diffractive lens element having a first focal length for the first light, a second focal length for the second light, and a third focal length for the third light,
the first focal length is longer than the secon

Assignees

• Samsung Electronics Co Ltd

Inventors

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

Classifications

• G02B27/0068 Primary

  having means for controlling the degree of correction, e.g. using phase modulators, movable elements (controlling the phase of light using moving or deformable elements G02B26/06) · CPC title

• G03H1/2286

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

• G03H2001/221

  Element having optical power, e.g. field lens · CPC title

• G03H2001/2234

  Transmission reconstruction · CPC title

• G03H2222/18

  RGB trichrome light · CPC title