Bringing Film Into Focus: Katharine Blodgett’s Glaring Success

As we close out our series on women in IP (read our first, second, third, and fourth posts) we’d like to sharpen the focus on the woman who developed the precursor to high-definition video, which revolutionized the movie business and proved invaluable to the U.S. military in wartime.

Born before the turn of the century, Katharine Blodgett didn’t take long to prove herself as a pioneer for women at the time. During her senior year at Bryn Mawr College, she turned an informational tour of General Electric (GE) laboratories into an incredible career in science.

After a stint as a lab assistant at GE and at the advice of her mentor at GE Irving Langmuire, Blodgett became the first woman to receive a PhD in physics from Cambridge.

Then, another first: she returned to GE as the company’s first female research scientist. In this capacity, Blodgett developed a way to transfer single-molecule thin coating films from a water surface to a solid surface. She would spread these coatings one at a time onto glass or metal, until she was able to build up films of nearly 3,000 single-molecule layers. These multilayer films became known as Langmuir-Blodgett films.

Before Langmuir-Blodgett films, even the clearest glass was far from invisible, reflecting as much as 10 percent of incident light. Blodgett realized that her films, if developed and applied at the perfect thickness, could cancel out the reflections from a glass surface that made the glass difficult to see through.

She found perfect thickness: a film coating with a thickness just ¼ the average wavelength of visible light.

With the film coating in place, any light that reflected off of the glass would have traveled half a wavelength farther than the light that had reflected off of the film surface; in short, the reflections would cancel out.

On March 16, 1938, Blodgett received a patent for her invention: “Film Structure and Method of Preparation.” GE announced her discovery shortly after, coined “invisible glass.”

Soon, Blodgett’s work had gone global. Gone with the Wind (1939) was the first major movie to use Blodgett’s invisible glass, and it was applauded for its crystal-clear cinematography. Within a few years, the entire movie industry would use invisible glass for all of its projectors and cameras. Even World War II submarine periscopes and airplane spy cameras relied on invisible glass.

Blodgett’s invention – and her rare status as a female scientist at the time – proved to be a sensation. She received the Achievement Award from the American Association of University Women and the Francis Garvan Medal from the American Chemical Society. As recently as 2007, she was inducted into the National Inventors Hall of Fame. (Not to mention the U.S. Chamber of Commerce selected her as one of 15 women of achievement in 1951.)

By the end of her career, Blodgett would receive seven additional patents: for developing gas absorbents; creating a method for de-icing aircraft wings; and improving battlefield smokescreens.

Katharine Blodgett’s amazing legacy is everywhere – just look around. Today, variations of her invisible glass technique are used to reduce vision-impairing reflections in eyeglasses, microscopes, windshields, and more.

We’re grateful for her many inventions and her trailblazing spirit that opened doors for women in science across the world.

Ashley Mergen is the senior manager of international intellectual property for the U.S. Chamber of Commerce’s Global Intellectual Property Center.

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