Active prism structure and fabrication method therefor

Patent metadata

Field	Value
Publication number	US-10816870-B2
Application number	US-201815894216-A
Country	US
Kind code	B2
Filing date	Feb 12, 2018
Priority date	Feb 23, 2017
Publication date	Oct 27, 2020
Grant date	Oct 27, 2020

Abstract

An active prism structure includes: an isotropic layer made of a photocurable isotropic polymer having a predetermined refractive index np and stacked on a substrate; and a birefringent layer made of a birefringent material having an ordinary refractive index no and an extraordinary refractive index ne and stacked on the isotropic layer, an interface between the isotropic layer and the birefringent layer is formed in a prism shape, and refractive index differences occurring at the interface between the isotropic layer and the birefringent layer are different according to a polarization direction of incident light. The active prism structure is configured such that the refractive index differences are different according to the polarization direction of the incident light, and thus, it is possible to change a refraction angle and refraction direction of the prism by controlling the polarization direction of the incident light.

First claim

What is claimed is:

1. An active prism structure comprising:
a substrate made of a transparent material;
an isotropic layer stacked on the substrate and made of a photocurable isotropic polymer having a predetermined refractive index n p ; and
a birefringent layer stacked on the isotropic layer and made of a birefringent material having an ordinary refractive index n o and an extraordinary refractive index n e ,
wherein the predetermined refractive index n p is different from the ordinary refractive index n o and the extraordinary refractive index n e ,
wherein a refraction angle and a refraction direction of a prism are determined according to a polarization direction of an incident light,
wherein an interface between the isotropic layer and the birefringent layer is formed in a prism shape, and
wherein refractive index differences occurring at the interface between the isotropic layer and the birefringent layer are different according to the polarization direction of the incident light.

2. The active prism structure according to claim 1 , wherein the birefringent material includes a birefringent liquid crystal or a photocurable liquid crystalline phase polymer.

3. The active prism structure according to claim 1 , further comprising a lower alignment film formed at the interface between the birefringent layer and the isotropic layer,
wherein the birefringent material is aligned by the lower alignment film.

4. The active prism structure according to claim 1 , further comprising an upper transparent substrate stacked on a surface of the birefringent layer,
wherein an upper alignment film is formed on one surface of the upper transparent substrate being in contact with the birefringent layer, and
wherein the birefringent material is aligned by the upper alignment film.

5. The active prism structure according to claim 1 , wherein the prism is formed at the interface between the isotropic layer and the birefringent layer and is configured to have a triangular shape, and the prism is configured as a single prism or a prism array.

6. The active prism structure according to claim 1 , wherein the prism is formed at the interface between the isotropic layer and the birefringent layer and is configured as a single prism having a right triangular shape or a prism array having a Fresnel prism shape.

7. A method of fabricating an active prism structure, comprising:
(a) forming an isotropic layer on a first transparent substrate by depositing an isotropic polymer on the first transparent substrate, pressing the deposited isotropic polymer by using a prism template having a reversed prism shape, photocuring the pressed isotropic polymer, and removing the prism template;
(b) forming a lower alignment film for bottom-up alignment on a surface of the isotropic layer by coating an alignment material on the surface of the isotropic layer and performing rubbing;
(c) forming an upper substrate having an upper alignment film for top-down alignment by coating an alignment material on a second transparent substrate and performing rubbing;
(d) forming a birefringent layer by arranging the upper substrate above the lower alignment film on the first transparent substrate, injecting a photocurable liquid crystalline phase polymer between the lower alignment film and the upper alignment film, and performing photocuring; and
(e) separating and removing the upper substrate having the upper alignment film from the birefringent layer,
wherein an interface between the isotropic layer and the birefringent layer is configured as a prism shape, and
wherein the isotropic polymer and the photocurable liquid crystalline phase polymer are configured as materials so that refractive index differences occurring at the interface between the isotropic layer and the birefringent layer are different according to a polarization direction of incident light.

8. The method according to claim 7 , wherein the (b) forming the lower alignment film further includes a process of UVO-treating the surface of the isotropic layer before coating the alignment material on the surface of the isotropic layer, so that coatability of the alignment material is improved.

9. The method according to claim 7 , wherein the isotropic polymer includes a photocurable isotropic polymer having a refractive index n p equal to an ordinary refractive index of the birefringent layer, and control of turning on/off a prism function is determined according to the polarization direction of the incident light.

10. The method according to claim 7 , wherein the isotropic polymer includes a photocurable isotropic polymer having a refractive index n p different from an ordinary refractive index and an extraordinary refractive index of the birefringent layer, and a refraction angle and a refraction direction of a prism are determined according to the polarization direction of the incident light.

11. The method according to claim 7 , wherein the prism template is configured as a single prism template or a prism array template, and
wherein the prism template is configured to form a triangular shape or a Fresnel prism shape.

Assignees

• Kyungpook Nat Univ Ind Academic Coop Found

Inventors

• Kim Hak-Rin
• Park Min-Kyu

Classifications

• G02F1/293 Primary

  by another light beam, i.e. opto-optical deflection · CPC title

• G02B5/3083

  Birefringent or phase retarding elements (G02B5/3008, G02B5/3016 take precedence; systems for polarisation control G02B27/286; manufacturing phase modulating patterns by lithographic processes G03F7/001) · CPC title

• G02B5/04

  Prisms · CPC title

• G02B5/3066 Primary

  involving the reflection of light at a particular angle of incidence, e.g. Brewster's angle · CPC title

• G02F2202/40

  Materials having a particular birefringence, retardation · CPC title