Striped dichroic filter and method for making the same

• US 3,914,464 A
• Filed: 05/21/1973
• Issued: 10/21/1975
• Est. Priority Date: 04/19/1971
• Status: Expired due to Term

• Current Assignee: David G. Thomasson, Frederick K. Crosher, Leroy A. Bartolmei, Michael D. Temple, Richard Ian Seddon
• Original Assignee: David G. Thomasson, Frederick K. Crosher, Leroy A. Bartolmei, Michael D. Temple, Richard Ian Seddon
• Inventors: Thomasson, David G., Crosher, Frederick K., Temple, Michael D., Bartolmei, Leroy A., Seddon, Richard Ian
• Primary Examiner(s): Drummond, Douglas J.
• Assistant Examiner(s): Gallagher, J. J.
• Application Number:
  US05/362,220
• Time in Patent Office: 883 Days
• Field of Search: 117/1.7,8,8.5,33.3,45,69,12R,159,211,215,5.5,33.3CM 350/164,316,172,317 156/3,11 96/36.1,36.2 340/366B 313/471,474
• US Class Current: 430/321
• CPC Class Codes: G02B 5/285 comprising deposited thin solid films G02B5/281 - G02B5/289 take precedence; multilayered film filters for fibre optic multiplexing G02B6/29361
• CPC Class Codes: G03B 33/00 Colour photography, other than mere exposure or projection of a colour film printing apparatus G03B27/00; stereoscopic colour photography G03B35/00

Abstract

Striped dichroic filter having a substantially transparent glass substrate with a surface and having first and second sets of spaced parallel stripes disposed on said surface at an angle with respect to each other and with each of said sets of stripes being capable of reflecting at least one different color and with the stripes being formed of a plurality of layers of high and low index dielectric materials. In the method for making a striped dichroic filter, first and second sets of spaced parallel stripes are sequentially formed by sequentially depositing dielectric coating materials on sequentially formed striped material which is subsequently etched away to remove the undesired portions of the coating material so that there remains first and second sets of spaced parallel stripes at angles with respect to each other and with each being capable of reflecting at least one different color.

Claims

1. IN A METHOD FOR MAKING A STRIPPED DICHLORIC FILTER ON A SUBSTANTIALLY TRANSPARENT GLASS SUBSTRATE HAVING A SURFACE WITH THE USE OF A MASK HAVING A PLURALITY OF SPACED PARALLEL STRIPS THEREON, FORMING A LAYER OF MATERIAL ON SAID SURFACE OF SAID SUBSTRATE, REMOVING CERTAIN PORTIONS OF THE MATERIAL SO THAT THERE REMAINS ON SAID SURFACE A PLURALITY OF SPACED PARALLEL STRIPS OF SAID MATERIAL WITH EXPOSED AREAS OF SAID SURFACE THEREBETWEEN, PLACING A PLURALITY OF LAYERS OF HIGH AND LOW INDEX DIELECTRIC COATING MATERIALS ON SAID STRIPS AND ON SAID EXPOSED AREAS OF SAID SURFACE TO A DEPTH WHICH IS SUBSTANTIALLY LESS THAN THE HEIGHT OF THE STRIPES SO THAT THE SIDE WALLS OF THE STRIPES ARE EXPOSED, AND ETCHING AWAY THE STRIPES TO PERMIT LIFTING OFF OF THE PORTIONS OF THE DIELECTRIC COATING MATERIALS CARRIED BY THE STRIPES SO THAT THERE REMAINS ON SAID SURFACE A FIRST SET OF STRIPES FORMED OF SAID LAYERS OF HIGH AND LOW INDEX DIELCTRIC COATING MATERIALS CAPABLE OF RELECTING AT LEAST ONE COLOR.

2. A method as in claim 1 together with the steps for forming additional material on the first set of stripes and on said surface, removing some of the additional material so that there remains an additional plurality of spaced parallel stripes of the additional material with exposed areas of said surface therebetween, placing a plurality of layers of high and low index dielectric coating materials on the additional stripes and on said exposed areas of said surface and said first set of stripes to a depth which is less than the height of the additional material, and etching away the exposed additional stripes so as to lift off the additional coating materials so that there remains a second set of stripes capable of reflecting at least one color different from the color reflected by the first set of stripes.

3. A method in claim 1 wherein said material is a negative photoresist.

4. A method as in claim 1 wherein said material is a metal.

5. A method as in claim 2 together with the step of forming additional material on said first and second stripes and said surface, removing portions of said last named additional material so that there remains a plurality of stripes in said material with expOsed areas of said surface therebetween, placing a plurality of layers of high and low index dielectric coating materials on said last named stripes and on said exposed areas of said surface to a depth which is substantially less than the height of the last named additional material such that the side walls of the last named additional material are exposed, and etching away the exposed last named additional material so as to lift off portions of the coating so that there remains a third set of stripes capable of reflecting at least one color different from the colors reflected by the first and second set of stripes.

6. In a method for making a striped dichroic filter on a substantially transparent glass substrate having first and second surfaces with the use of a mask having a plurality of spaced parallel stripes thereon, forming a layer of negative photoresist on said first surface of said substrate, exposing said photoresist utilizing said mask, developing the photoresist to remove certain portions of the photoresist so that there remains on said first surface a plurality of spaced parallel stripes of photoresist, baking the photoresist, depositing a multilayer dielectric coating on said photoresist stripes and on said first surface to a depth which is substantially less than the height of the photoresist so that the side walls of the photoresist are exposed, and etching away the exposed photoresist so as to lift off the portions of the layer of the coating carried by the photoresist and to remove the remainder of the photoresist so that there remains on said first surface a first set of spaced parallel stripes of a color reflecting coating.

7. A method as in claim 6 together with the step of forming an additional layer of positive photoresist on said surface and on said color reflecting stripes, exposing the additional photoresist utilizing the mask to provide a plurality of spaced parallel exposed stripes which extend at an angle with respect to the color reflecting stripes, developing the additional photoresist so that there remains a plurality of photoresist stripes which extend over said surface and over said color reflecting stripes, baking the photoresist, depositing a different color reflecting multilayer dielectric coating on said additional photoresist to a depth which is less than the height of the additional photoresist so that the side walls of the additional photoresist are exposed, and etching away the additional photoresist to lift off the coating material carried thereby so there remains a second set of stripes of the different color reflecting coating material which extend at an angle to the first set of color reflecting stripes.

8. A method as in claim 6 wherein said photoresist is deposited at a depth of 4 to 6 microns and wherein said coating is deposited to a depth of approximately 2 microns.

9. A method as in claim 7 wherein said first set of stripes of coating material reflect in the red and wherein said second named color reflecting stripes reflect in the blue.

10. A method as in claim 7 together with the step of depositing an additional layer of positive photoresist on said red reflecting and blue reflecting stripes, utilizing the master to expose the last named additional photoresist, removing portions of the last named additional photoresist so that there remains photoresist stripes extending at an angle with respect to said first and second sets of color reflecting stripes, and depositing a color transmitting multilayer dielectric coating on said last named additional photoresist and in the spaces between the last named additional photoresist to a depth so that the side walls of the last named additional photoresist are exposed, removing the last named additional photoresist from a portion of the coating material covered thereby so that there remains a third set of spaced parallel green reflecting stripes which extend at an angle with respect to the red reflecting and the blue reflecting stripes.

11. A method as in claim 6 wherein said photoresist is exposed through the mask by the use of a collimated light source.

12. A method as in claim 6 together with the step of applying a red antihalation coating to the second surface of the substrate to minimize second surface reflections from the substrate.

13. A method as in claim 6 wherein said photoresist is a positive photoresist.

14. A method as in claim 6 wherein heated Xylene is utilized for etching away the photoresist.

15. A method as in claim 6 wherein said Xylene has a temperature of approximately 100*C.