An Analysis of Low-Reflection Coatings as Applied to Glass

W. P. Strickland

A brief summary of the development of the low-reflection coating is given. As instruments were improved, a point was soon reached where further improvement in optical design required elimination of surface reflections. An explanation of the color effect observed in a coating and a method of applying a film whose index varies from top to bottom which will eliminate the color effect is described. A comparison is drawn between the coating produced by natural aging, nitric acid, hydrofluoric acid, magnesium fluoride, and the American Optical Company low-reflection coatings. This shows that the magnesium fluoride is the most practical film to date when all factors are taken into consideration. The American Optical method of applying coatings without using vacuum is described. There are four main advantages in using a low-reflection coating: (1) elimination of reflections, (2) increased transmission, (3) increased contrast, and (4) increased chemical stability. Several tests are outlined which indicate that glass properly coated with magnesium fluoride will withstand more chemical abuse than uncoated glass. A new method of removing a high-temperature-baked low-reflection coating using melted crystals of potassium bisulfate is described which will materially speed the decoating process.

Print ISSN
Published
1947-07
Content type
Original Research
DOI
10.5594/J12685