Color tuned holographic optical elements and methods of making and using the elements

• US 5,526,145 A
• Filed: 06/10/1994
• Issued: 06/11/1996
• Est. Priority Date: 06/10/1994
• Status: Expired due to Term

• Current Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Original Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Inventors: Weber, Andrew M.
• Primary Examiner(s): Dzierzynski, Paul M.
• Assistant Examiner(s): CHANG, AUDREY Y
• Application Number:
  US08/258,036
• Time in Patent Office: 732 Days
• Field of Search: 359/9, 359/15, 359/21, 359/64, 359/66, 359/71, 359/40, 430/1, 430/2, 252/584
• US Class Current: 359/15
• CPC Class Codes: G02B 5/201 in the form of arrays
• CPC Class Codes: G02B 5/203 having holographic or diffractive elements diffraction gratings per se G02B5/18; holographic elements per se G02B5/32; generating the spectrum using diffraction elements G01J3/18
• CPC Class Codes: G02B 5/32 Holograms used as optical elements
• CPC Class Codes: G02F 1/133514 Colour filters
• CPC Class Codes: G03H 1/0248 Volume holograms
• CPC Class Codes: G03H 2001/0264 Organic recording material
• CPC Class Codes: G03H 2001/186 Swelling or shrinking the holographic record or compensation thereof, e.g. for controlling the reconstructed wavelength G03H2001/0033, G03H2250/44 take precedence
• CPC Class Codes: G03H 2222/13 Multi-wavelengths wave with discontinuous wavelength ranges G03H2222/18 takes precedence
• CPC Class Codes: G03H 2250/32 Antireflective layer
• CPC Class Codes: G03H 2250/44 Colour tuning layer

Abstract

The present invention relates to color tuned holographic multicolor optical elements for use as multicolor transmission filters in liquid crystal displays and methods of making the elements. The element comprises at least first and second pixel volumes containing holographic mirrors and preferably third pixel volumes containing holographic mirrors. Each set of pixel volumes passes a different color wavelength band and reflects other color wavelength bands.

Claims

1. A color tuned volume holographic optical element, for use with a light source having spectral power peaks at a first color, a second color, and a third color, comprising:

a photohardened holographic recording film element comprising a first plurality of pixel volumes, a second plurality of pixel volumes, and a third plurality of pixel volumes;

each one of the first pixel volumes including a color tuned volume holographic mirror that passes light with a first color wavelength band and reflects light with a second color wavelength band, a third color wavelength band and a fourth color wavelength band and passes all other color wavelength bands;

each one of the second pixel volumes including a non-color tuned volume holographic mirror that passes light with the second color wavelength band and reflects light with the first color wavelength band, the third color wavelength band and a fifth color wavelength band and passes all other color wavelength bands;

each one of the third pixel volumes including a color tuned volume holographic mirror that passes light with the third color wavelength band and reflects light with the first color wavelength band, the second color wavelength band, and a sixth color wavelength band and passes all other color wavelength bands.

2. The element of claim 1, wherein the first color wavelength band has a width of at least 5 nanometers and includes 634 namometer, the second color wavelength band has a width of at least 5 nanometers and includes 528 nanometer, and the third color wavelength band has a width of at least 5 nanometers and includes 440 nanometer.

3. The element of claim 1, wherein the fourth color wavelength band has a width of at least 5 nanometers and includes 760 nanometer, the fifth color wavelength band has a width of at least 5 nanometers and includes 367 namometer, and the sixth color wavelength band has a width of at least 5 nanometers and includes 912 nanometer.

4. The element of claim 1, wherein the film element comprises a single photohardened holographic recording film.

5. The element of claim 1, wherein the film element comprises a plurality of photohardened holographic recording films.

6. In a transmission liquid crystal display apparatus, comprising, in order:

a light assembly, Comprising a light source, which emits light with spectral peaks at a first color wavelength band, a second color wavelength band and a third color wavelength band;

a first light polarizer for passing light from the light assembly having a first polarization;

a liquid crystal display element for selectively modifying the polarization of the light passing through an array of cells such that the polarization of light passing through a first set, a second set or a third set of the cells can be changed to a second polarization;

a color tuned holographic multicolor transmission filter comprising a first plurality of pixel volumes, a second plurality of pixel volumes, and a third plurality of pixel volumes;

each one of the first pixel volumes including a color tuned volume holographic mirror that passes light with the first color wavelength band and reflects light with the second color wavelength band, the third color wavelength band and a fourth color wavelength band;

each one of the second pixel volumes including a non-color tuned volume holographic mirror that passes light with the second color wavelength band and reflects light with the first color wavelength band, the third color wavelength band and a fifth color wavelength band; and

each one of the third pixel volumes including a color tuned volume holographic mirror that passes light with the third color wavelength band and reflects light with the first color wavelength band, the second color wavelength band and a sixth color wavelength band; and

a second light polarizer for passing light having a second polarization,

such that (1) when the liquid crystal display element modifies the polarization of the light passing through the first set of cells to the second polarization, the light passes into the first pixel volumes in which the first volume holographic mirrors pass light with the first color wavelength band through the second polarizer to a viewer, (2) when the liquid crystal display element modifies the polarization of the light passing through the second set of cells to the second polarization, the light passes into the second pixel volumes in which the second volume holographic mirrors pass light with the second color wavelength band through the second polarizer to the viewer, and (3) when the liquid crystal display element modifies the polarization of the light passing through the third set of cells to the second polarization, the light passes into the third pixel volumes in which the third volume holographic mirrors pass light with the third color wavelength band through the third polarizer to the viewer.

7. The transmission liquid crystal display apparatus of claim 6, further comprising a pre-filter adjacent the light assembly for reflecting or absorbing light with other color wavelength bands.

8. The transmission liquid crystal display apparatus of claim 6, further comprising a pre-filter adjacent the light assembly for reflecting and absorbing light with other color wavelength bands.

9. A method for making a first color tuned volume holographic optical element, comprising:

a holographic recording film element comprising a first plurality of pixel volumes, a second plurality of pixel volumes, and a third plurality of pixel volumes;

each one of the first pixel volumes including a color tuned volume holographic mirror that passes light with a first color wavelength band and reflects light with a second color (e.g., Green) wavelength band, a third color wavelength band and a fourth color wavelength band;

each one of the second pixel volumes including a non-color tuned volume holographic mirror that passes light with the second color wavelength band and reflects light with the first color wavelength band, the third color wavelength band and a fifth color wavelength band; and

each one of the third pixel volumes including a color tuned volume holographic mirror that passes light with the third color wavelength band and reflects light with the first color wavelength band, the second color wavelength band and a sixth color wavelength band;

the method comprising;

holographically exposing the film element with coherent or substantially coherent light in a uniform manner to record a second volume holographic optical element adapted to uniformly reflect light having the fifth color wavelength band, the third color wavelength band and the first color wavelength band;

contacting a solid or substantially solid diffusing element containing a diffusable monomer with the film element; and

imagewise exposing the diffusing element to actinic radiation to polymerize the monomer to varying degrees, the imagewise exposure creating three sets of pixels, wherein,

each first pixel, which corresponds to each first pixel volume, is subjected to a partial polymerization,

each second pixel, which corresponds to each second pixel volume, is subjected to a substantially complete polymerization, and

each third pixel, which corresponds to each third pixel volume, is subjected to substantially no polymerization, to selectively modify the wavelength response of the holographic optical element by the diffusion of monomer from the diffusion element to form the first color tuned volume holographic optical element.

10. A method for making a first color tuned volume holographic optical element, comprising:

a holographic recording film element comprising a first plurality of pixel volumes, a second plurality of pixel volumes, and a third plurality of pixel volumes;

each one of the first pixel volumes including a color tuned volume holographic mirror that passes light with a first color wavelength band and reflects light with a second color wavelength band, a third color wavelength band and a fourth color wavelength band;

each one of the second pixel volumes including a non-color tuned volume holographic mirror that passes light with the second color wavelength band and reflects light with the first color wavelength band, the third color wavelength band and a fifth color wavelength band; and

each one of the third pixel volumes including a color tuned volume holographic mirror that passes light with the third color wavelength band and reflects light with the first color wavelength band, the second color wavelength band and a sixth color wavelength band;

the method comprising;

holographically exposing the film element with coherent or substantially coherent light to record a second volume holographic optical element adapted to uniformly reflect light having a fifth color wavelength band, the third color wavelength band and the first color wavelength band;

imagewise exposing a solid or substantially solid diffusing element containing a diffusable monomer to actinic radiation to polymerize the monomer to varying degrees, the imagewise exposure creating three patterns of pixel regions, wherein

each first pixel region, which corresponds to each first pixel volume, is subjected to a partial polymerization,

each second pixel region, which corresponds to each second pixel volume, is subjected to a substantially complete polymerization, and

each third pixel region, which corresponds to each third pixel volume, is subjected to substantially no polymerization; and

contacting the film element with the diffusing element to selectively modify the wavelength of light response of the second volume holographic optical element by diffusion of the monomer from the solid diffusing element to form the first color tuned volume holographic optical element.

11. The method of claim 9 or 10, further comprising, after the holographically exposing step and before the contacting step, curing the holographic recording film element by exposing it to actinic radiation to substantially polymerize any monomer and fix the holographic mirrors in the film element.

12. The method of claim 9 or 10, further comprising, after the imagewise exposing and contacting steps, heating the holographic recording film to increase the refractive index modulation, efficiency and bandwidth of the holographic mirrors.

13. The method of claim 9 or 10, wherein the film element comprises a single, substantially solid, holographic recording film.

14. The method of claim 9 or 10, wherein the film element comprises a plurality of substantially solid, holographic recording films.

15. The method of claim 9 or 10, wherein the first color wavelength band has a width of at least 5 nanometers and includes 634 nanometer, the second color wavelength band has a width of at least 5 nanometers and includes 528 nanometer, and the third color wavelength band has a width of at least 5 nanometers and includes 440 nanometer.

16. The method of claim 15, wherein the fourth color wavelength band has a width of at least 5 nanometers and includes 760 nanometer, the fifth color wavelength band has a width of at least 5 nanometers and includes 367 nanometer, and the sixth color wavelength band has a width of at least 5 nanometers and includes 912 nanometer.