Method for making an optical device using a laser beam interference pattern

• US 5,748,272 A
• Filed: 06/10/1996
• Issued: 05/05/1998
• Est. Priority Date: 02/22/1993
• Status: Expired due to Term

• Current Assignee: Nippon Telegraph and Telephone Corporation
• Original Assignee: Nippon Telegraph and Telephone Corporation
• Inventors: Tanaka, Keiji, Kato, Kinya, Sakai, Shigenobu, Tsuru, Shinji
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): NGUYEN, TIEP HUU
• Application Number:
  US08/661,018
• Time in Patent Office: 694 Days
• Field of Search: 349/86, 349/92, 349/105, 349/183, 349/186
• US Class Current: 349/86
• CPC Class Codes: G02F 1/13342 Holographic polymer dispersed liquid crystals
• CPC Class Codes: G02F 1/13478 based on selective reflection

Abstract

A polymer dispersed liquid crystal optical device is presented which has optical elements which control reflection, transmission and diffraction of incident light entering the device by adjusting the magnitude of the electrical field applied to the device between a maximum and a minimum limits. An optical element consists of a polymer material having an electrical field-independent refractive index, and a liquid crystal material having an electrical field-dependent refractive index. The optical elements are distributed through the device at specific inter-element spacings, thus enabling to generate reflection of incident light in accordance with Bragg'"'"'s law of reflection. The inter-element spacings can also be varied by the application of the field, thus enabling to generate reflection of light of a desired wavelength. Such optical elements are ideal for use in full color optical display apparatus of a matrix driven type. Methods for producing the optical device and optical display apparatus are also presented.

Claims

1. A method for making an optical device comprising the steps of:

(a) preparing a pair of transparent electrodes;

(b) disposing a mixture solution containing a light hardenable polymer material and a liquid crystal material between said pair of transparent electrodes;

(c) irradiating said mixture solution with a plurality of process laser beams, each process laser beam being oriented at a specific process angle with respect to an incident surface of said optical device and said plurality of process laser beams forming an interference pattern in said mixture solution; and

(d) controlling the rate of hardening of said light hardenable polymer material to generate a plurality of optical elements formed by said interference pattern having at least one periodicity in inter-element spacings, thereby forming said optical device which regulates reflection, transmission and diffraction of incident light entering said optical device by the application of an electrical field on said pair of transparent electrodes.

2. A method of making an optical device as claimed in claim 1 wherein said process laser beams are coherent laser beams of a singular wavelength.

3. A method of making an optical device as claimed in claim 1, wherein said process laser beams are coherent laser beams of a plurality of wavelengths.

4. A method of making an optical device as claimed in claim 1, wherein said specific process angle is determined on the basis of wavelengths of the incident light entering said optical device and a desired angle of diffraction of the incident light.

5. A method of making an optical device as claimed in claim 1, wherein said optical elements are orientated parallel to the incident surface of said optical device.

6. A method of making an optical device as claimed in claim 1, wherein said optical elements are oriented at a right angle with respect to the incident surface of said optical device.

7. A method of making an optical device as claimed in claim 1, wherein said optical elements are oriented at a specific singular angle with respect to the incident surface of said optical device.

8. A method of making an optical device as claimed in claim 1, wherein said optical elements are oriented at a plurality of specific angles with respect to the incident surface of said optical device.

9. A method of making an optical device as claimed in claim 1, wherein said mixture solution is treated with said process laser beams so that each of the plurality of optical elements includes the polymer material having an electrical field-independent refractive index and the liquid crystal material having an electrical field-dependent refractive index.

10. A method of making an optical device as claimed in claim 9, wherein volumes of different ones of the liquid crystal material in the plurality of optical elements are not the same.

11. A method of making an optical device as claimed in claim 9, wherein in the plurality of optical elements, a total volume of the polymer material and a total volume of the liquid crystal material are different.