Reflection reduction coatings and method for coating same

• US 2,782,676 A
• Filed: 03/01/1952
• Issued: 02/26/1957
• Est. Priority Date: 03/01/1952
• Status: Expired due to Term

• Current Assignee: Harold Osterberg
• Original Assignee: Harold Osterberg
• Inventors: Osterberg, Harold
• Application Number:
  US03/274,456
• Time in Patent Office: 1,823 Days
• US Class Current: 359/586
• CPC Class Codes: G02B 1/115 Multilayers
• CPC Class Codes: Y10S 359/90 Methods

Claims

1. AN OPTICAL ELEMENT HAVING A HARD, DURABLE REFLECTION-REDUCTION BILAYER COATING BONDED TO A SURFACE THEREOF AND ARRANGED TO PROVIDE AN EXPOSED SURFACE HAVING SUBSTANTIALLY ZERO REFLECTIVITY AT A PRESELECTED WAVELENGTH, SAID OPTICAL ELEMENT BEING FORMED OF A TRANSPARENT MATERIAL HAVING A PREDETERMINED REFRACTIVE INDEX NO, A FIRST LAYER OF SUBSTANTIALLY CLEAR DIELECTRIC MATERIAL HAVING A HIGH REFRACTIVE INDEX N1 RELATIVE TO THE REFRACTIVE INDEX OF SAID OPTICAL ELEMENT AND BEING A VALUE WITHIN THE RANGE OF 1.8 TO 4.5, SAID LAYER BEING DISPOSED UPON SAID SURFACE OF SAID ELEMENT AND PROVIDING A FIRST INTERFACE THEREBETWEEN, AND A SECOND LAYER OF SUBSTANTIALLY CLEAR DIELECTRIC MATERIAL HAVING A LOW REFRACTAIVE INDEX N2 RELATIVE TO THE REFRACTUVE INDEX OF SAID FIRST LAYER AND BEING A VALUE WITHIN THE RANGE OF 1.3 TO 1.6, SAID SECOND LAYER BEING DISPOSED UPON TAHE SURFACE OF SAID FIRST LAYER AND PROVIDING A SECOND INTERFACE THEREBETWEEN, THE OPTICAL WITH PATH VALUE P1 (THE ACTUAL THICKNESS EXPRESSED IN WAVELENGTH VALUE X REFRACTIVE INDEX N1) OF SAID FIRST LAYER BEING IN A RANGE BETWEEN 1/20 OF A WAVELENGTH TO 1/100 OF A WAVELENGTH AT SAID PRESELECTED WAVELENGTH AND BEING THAT VALUE WITHIN SAID LATTER RANGE WHICH SATISFIES THE FOLLOWING EQUATION: