METHOD FOR THE PREPARATION OF MULTILAYER OPTICAL FILTERS

• US 3,847,585 A
• Filed: 01/08/1973
• Issued: 11/12/1974
• Est. Priority Date: 01/08/1973
• Status: Expired due to Term

• Current Assignee: Douglas S. Chisholm
• Original Assignee: Douglas S. Chisholm
• Inventors: Chisholm, Douglas S.
• Primary Examiner(s): Bashore, S. Leon
• Assistant Examiner(s): Miga, Frank W.
• Application Number:
  US05/321,792
• Time in Patent Office: 673 Days
• Field of Search: 65/121,DIG.7,145,182R,145,3,99A 350/151 161/164 264/171
• US Class Current: 65/99.2
• CPC Class Codes: C03B 17/02 Forming molten glass coated with coloured layers; Forming molten glass of different compositions or layers; Forming molten glass comprising reinforcements or inserts
• CPC Class Codes: C03B 18/12 Making multilayer, coloured or armoured glass chemical aspects C03C
• 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: Y10T 428/2495 Thickness [relative or absolute]

Abstract

Optical filters are prepared from transparent glasses by the formation of multilayer streams of molten glass. The optical filter is formed by flowing molten first and second glass compositions substreams and interdigitating the substreams into a composite stream on a bath and shaping the composite stream that the interfaces of the substreams are parallel to the major surface of the composite stream. By choice of layer thickness reflection can be obtained in infrared, visible ultraviolet range.

Claims

1. A method for the preparation of a multilayer optical filter, the steps of the method comprising providing at least first and second thermoplastic transparent glass compositions, dividing the first and second glass compositions into first and second substreams, interdigitating the first and second substreams to provide a single composite stream, deforming the single composite stream to alternate the shape of the substreams to provide the substreams with a plurality of interfaces, the interfaces being deposited in generally parallel planes which are parallel to a major surface of the composite stream and being separated by a distance from about 0.05 micron to about one micron, with the further limitation that the first and second glass compositions have refractive indices which differ from each other by at least about 0.05.

2. The method of claim 1 wherein the first and second glass compositions are interdigitated to form a stream having a plurality of alternating strips of the first and second compositions in side by side relationship, subsequently compressing the composite stream in the direction of its width and expanding the stream in the direction of its thickness to thereby provide a composite glass stream having a plurality of layers therein extending generally parallel to a major surface of the composite stream.

3. The method of claim 1 wherein the composite stream is floated on the surface of a bath.

4. The method of claim 1 wherein the composite stream is stretched to provide interfaces having the desired spacing therebetween.

5. The method of claim 1 including the step of providing at least one layer of the finished composite stream having a thickness greater than about one micron.

6. The method of claim 1 including the step of providing surface layers having thicknesses greater than about one micron.