Holographic display device having reduced chromatic aberration

Patent metadata

Field	Value
Publication number	US-10884240-B2
Application number	US-201816233980-A
Country	US
Kind code	B2
Filing date	Dec 27, 2018
Priority date	Jul 4, 2018
Publication date	Jan 5, 2021
Grant date	Jan 5, 2021

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 holographic display device comprising:
a light source configured to emit light, the light comprising 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, wherein the 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 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 the optical axis to cancel chromatic aberration by the variable focus optical system.

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

3. The holographic display device of claim 2 , wherein the fixed-focus optical system comprises:
a first lens set configured to focus the first light of the first wavelength on a first position on the optical axis;
a second lens set configured to focus the second light of the second wavelength on a second position on the optical axis that is different from the first position; and
a third lens set configured to focus the third light of the third wavelength on a third position on the optical axis that is different from the first position and the second position.

4. The holographic display device of claim 3 , wherein a distance between the light source and the first position is less than a distance between the light source and the second position,
the distance between the light source and the second position is less than a distance between the light source and the third position,
the third wavelength is longer than the second wavelength, and
the second wavelength is longer than the first wavelength.

5. The holographic display device of claim 4 , wherein a distance between the light source and the first lens set is less than a distance between the light source and the second lens set, and
the distance between the light source and the second lens set is less than a distance between the light source and the third lens set.

6. The holographic display device of claim 4 , wherein the variable focus optical system comprises a variable focus diffractive lens element having a first focal length for the first light of the first wavelength, a second focal length for the second light of the second wavelength, and a third focal length for the third light of the third wavelength,
the first focal length is longer than the second focal length, and
the second focal length is longer than the third focal length.

7. The holographic display device of claim 6 , 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.

8. The holographic display device of claim 3 , wherein the first lens set comprises a first wavelength-selective polarization conversion element and a first anisotropic diffractive lens element,
the second lens set comprises a second wavelength-selective polarization conversion element and a second anisotropic diffractive lens element, and
the third lens set comprises a third wavelength-selective polarization conversion element and a third anisotropic diffractive lens element.

9. The holographic display device of claim 8 , 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 in a direction away from the light source.

10. The holographic display device of claim 8 , wherein the first wavelength-selective polarization conversion element is configured to polarize the first light of the first wavelength to have a first linear polarization component and polarize the second light of the second wavelength and the third light of the third wavelength 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 of the second wavelength to have the first linear polarization component and the first light of the first wavelength and the third light of the third wavelength to have the second linear polarization component, and
the third wavelength-selective polarization conversion element is configured to polarize the third light of the third wavelength to have the first linear polarization component and the first light of the first wavelength and the second light of the second wavelength to have the second linear polarization component.

11. The holographic display device of claim 10 , 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.

12. The holographic display device of claim 10 , wherein the fixed-focus optical system further comprises a fourth wavelength-selective polarization conversion element configured to polarize the first light of the first wavelength, the second light of the second wavelength and the third light of the third wavelength to have a same linear polarization component.

13. The holographic display device of claim 8 , wherein the first wavelength-selective polarization conversion element is configured to polarize the first light of the first wavelength to have a first circular polarization component and to polarize the second light of the second wavelength and the third light of the third wavelength 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 of the second wavelength to have the first circular polarization component and the first light of the first wavelength and the third light of the third wavelength to have the second circular polarization component, and
the third wavelength-selective polarization conversion element is configured to polarize the third light of the third wavelength to have the first circular polarization component and the first light of the first wavelength and the second light of the second wavelength to have the second circular polarization component.

14. The holographic display device of claim 13 , 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.

15. The holographic display device of claim 13 , wherein the fixed-focus optical system furthe

Assignees

• Samsung Electronics Co Ltd

Inventors

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

Classifications

• G03H1/2286

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• G03H2222/18

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• G03H2222/34

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• G03H2001/2234

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• G03H2226/05

  Means for tracking the observer · CPC title