Mask processing using films with spatially selective birefringence reduction

Patent metadata

Field	Value
Publication number	US-9423545-B2
Application number	US-201514755457-A
Country	US
Kind code	B2
Filing date	Jun 30, 2015
Priority date	Jun 30, 2010
Publication date	Aug 23, 2016
Grant date	Aug 23, 2016

Abstract

Certain patternable reflective films are used as masks to make other patterned articles, and one or more initial masks can be used to pattern the patternable reflective films. An exemplary patternable reflective film has an absorption characteristic suitable to, upon exposure to a radiant beam, absorptively heat a portion of the film by an amount sufficient to change a first reflective characteristic to a different second reflective characteristic. The change from the first to the second reflective characteristic is attributable to a change in birefringence of one or more layers or materials of the patternable film. In a related article, a mask is attached to such a patternable reflective film. The mask may have opaque portions and light-transmissive portions. Further, the mask may have light-transmissive portions with structures such as focusing elements and/or prismatic elements.

First claim

The invention claimed is:

1. A composite article comprising:
a film mask including a first group of layers arranged to extend continuously from a first zone to a second zone and selectively reflect light by constructive or destructive interference to provide a first reflective characteristic in the first zone and a second reflective characteristic in the second zone, the film mask having a first absorbing characteristic suitable to, upon exposure to a first radiant beam, absorptively heat a portion of the film mask by an amount of sufficient to change the first reflective characteristic to the second reflective characteristic, wherein the change from the first reflective characteristic to the second reflective characteristic is substantially attributable to a change in birefringence of at least some of the first group of layers of the film mask; and
a patternable film beneath the film mask and connected to the film mask in a layered arrangement, the patternable film having a first detectable characteristic at a selected portion that changes to a different second detectable characteristic upon exposure to a second radiant beam through the film mask,
wherein the film mask is capable of patterning the second radiant beam therethrough to change the first detectable characteristic to the second detectable characteristic at the selected portion of the patternable film.

2. The composite article of claim 1 , wherein the patternable film comprises a material that is excited at the second radiant beam.

3. The composite article of claim 2 , wherein the material of the patternable film comprises a fluorescent dye that emits at visible wavelengths upon exposing to the second radiant beam.

4. The composite article of claim 1 , wherein the first reflective characteristic reflects the second radiant beam more than the second reflective characteristic.

5. The composite article of claim 1 , wherein the selected portion of the patternable film corresponds to the second zone of the film mask.

6. The composite article of claim 1 , wherein the first reflective characteristic reflects the second radiant beam less than the second reflective characteristic.

7. The composite article of claim 1 , wherein the selected portion of the patternable film corresponds to portions of the film mask other than the second zone.

8. The composite article of claim 1 , wherein the first and second radiant beams comprise different first and second optical wavelengths, respectively.

9. The composite article of claim 8 , wherein the first optical wavelength is an infrared optical wavelength, and the second optical wavelength is less than 700 nm.

10. The composite article of claim 1 , wherein the first or second reflective characteristic has a reflectivity for the second radiant beam of at least 90%.

11. The composite article of claim 1 , wherein the article is a security construction including an identification card, a passport, or a driver's license.

12. The composite article of claim 1 , wherein the article is a security document, and the film mask comprises a personalizable feature in reference to a document holder.

13. The composite article of claim 1 , wherein the film mask and the patternable film are layered to provide combined security features.

14. A method of making a composite article, comprising:
providing a first film having a first reflective characteristic, the first film also having a first absorption characteristic suitable to, upon exposure to a first radiant beam, absorptively heat a portion of the first film by an amount sufficient to change the first reflective characteristic to a second reflective characteristic by a change in birefringence, and the first film comprising a first group of layers arranged to selectively reflect light by constructive or destructive interference to provide the first reflective characteristic, wherein the change from the first reflective characteristic to the second reflective characteristic is substantially attributable to a change in birefringence of at least some of the first group of layers of the first film;
providing a patternable film having a first detectable characteristic that changes to a different second detectable characteristic upon exposure to a second radiant beam, wherein the patternable film comprises a material that is excited at the second radiant beam;
directing the first radiant beam preferentially at a second zone rather than a first zone of the first film to change the first reflective characteristic to the second reflective characteristic in the second zone by a change in birefringence so as to convert the first film to a film mask; and
arranging the film mask and the patternable film in a layered structure, using the film mask to pattern the second radiant beam, and directing the patterned second radiant beam at the patternable film to change the first detectable characteristic to the second detectable characteristic at a selected portion of the patternable film.

15. The method of claim 14 , wherein directing the first radiant beam preferentially at the second zone of the first film comprises scanning the first radiant beam over portions of the first film that define the second zone.

16. The method of claim 14 , wherein the selected portion of the patternable film corresponds to the first or second zone of the first film.

17. The method of claim 14 , wherein the first and second radiant beams comprise different first and second optical wavelengths, respectively.

18. The method of claim 17 , wherein the first optical wavelength is an infrared optical wavelength, and the second optical wavelength is less than 700 nm.

19. The method of claim 14 , wherein the material of the patternable film comprises a fluorescent dye that emits at visible wavelengths upon exposing to the second radiant beam, and directing the patterned second radiant beam at the patternable film forms a pattern of visible fluorescent light.

Assignees

• 3M Innovative Properties Co

Inventors

• Merrill William Ward
• Dunn Douglas S

Classifications

• B42D25/391

  absorbing or reflecting polarised light · CPC title

• G02B5/3083 Primary

  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

• G02B5/285

  comprising deposited thin solid films (G02B5/281 - G02B5/289 take precedence; multilayered film filters for fibre optic multiplexing G02B6/29361) · CPC title

• G02B1/12

  by surface treatment, e.g. by irradiation · CPC title

• G02B5/32

  Holograms used as optical elements · CPC title