What is Optical Coating?

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  • Written By: wiseGEEK Writer
  • Edited By: O. Wallace
  • Last Modified Date: 21 November 2019
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Optical coating or thin films coating is a manufacturing process in which products like glasses, mirrors, computer screens and fiber optic parts are coated with metals. Optical coating gives products the ability to reflect light in different ways, unlike uncoated products. Coating is usually accomplished by using machines operated by technicians, who program or oversee the machine processes. Some machines perform automated processes that do not need to be carefully overseen.

There are different types of demands for optical coating. In some cases, as in mirrors, the desired effect is to produce a product with a high degree of light reflection. By choosing materials with opposite levels of refraction and stacking them, one increases reflection in the finished product. For inexpensive mirrors, a typical optical coating material would be aluminum coating the glass. More expensive coatings, like silver, which result in more expensive mirrors, are of higher quality because they reflect more light.

In the case of lenses used for microscopes or cameras, optical coating is used to refract light, rather then reflect it. This is called dielectric coating, and its use is not only for consumers, but also for scientific devices like telescopes and lasers. Layers of metals like magnesium and fluoride are deposited onto the objects requiring coating (called the substrate), and levels of either reflection or refraction can be titrated depending upon the number and thickness of layers, the type of materials, and the coating processes used.


One of the most productive companies that utilized optical coating to great benefit, was the California based Optical Coating Labs Incorporated, which became a major employer in the 1970s, of the then relatively small town of Santa Rosa. They engineered such products as non-reflective computer screens, windows for the Space Shuttle, and mirrors for the Chandra x-ray telescope.

The company’s increasing skill and innovation interested the larger corporation, JDS Uniphase, which subsequently purchased the company in the late 1990s. While this move seemed to portend an even greater ability for the company to increase production, it instead ended up dismantling virtually the entire Optical Coating operation. This years-long drop in productivity resulted in the loss of jobs of approximately 1000 people.

The company’s downfall coincided with the telecom crash, since much of the work done at JDS Uniphase during this time was intended for fiber optics components. Since then, much of the optical coating work has moved overseas. There are some companies in the US with small operations devoted to coating a few specified products. Yet start-ups are subject to a high rate of failure, and many of the older machines are now sold to foreign countries like India or China. It is thought that production in optical coating will only be effective if new overseas companies employ American consultants to fix machines when they have problems, since this technology was primarily used and patented in the United States.


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