Happy International Day of Light! This UNESCO initiative celebrates the role of light “in science, culture and art, education, and sustainable development, and in fields as diverse as medicine, communications, and energy.”
The International Day of Light is held on May 16 in commemoration of the first successful operation of a laser on May 16, 1960. The history of the development of the laser, both before and after that day, illustrates some interesting aspects of innovation and intellectual property. For this year’s International Day of Light, let’s look back at the invention of the laser.
Progress Toward the Laser
Although a few key physical principles had been predicted decades earlier, most progress in the development of the laser occurred just a few years before the first working laser was announced in 1960. In fact, a similar device called the “maser” had been built in 1953. However, unlike the laser, the maser could output radiation only in the microwave portion of the electromagnetic spectrum. Even as the maser was being developed in the early 1950s, scientists and engineers envisioned a new version of the maser that could produce light at infrared, visible, or even ultraviolet wavelengths – in other words, a laser.
However, it was not at all obvious how to modify the maser design to produce light at these shorter wavelengths. Light produced by a maser or laser is emitted by a working medium of atoms or molecules that have been excited (that is, energized) into a suitable quantum state. The choice of working medium (also known as the gain medium) determines the wavelength of light produced. So switching from a maser to a laser required finding an appropriate working medium and a way of exciting it to produce light in the desired wavelength range.
Additionally, the working medium is typically placed inside a cavity that allows the medium and the light to interact. But the huge difference in size between microwave wavelengths and infrared, visible, or ultraviolet wavelengths meant that the geometry of the laser cavity would need to be substantially different from that of the maser. In order to build a laser, the right combination of laser medium, excitation method, and cavity design would be needed.
One of these issues – the question of cavity geometry – was solved independently by several researchers in the late 1950s. Among the best known of these researchers was Charles Townes, who had built the world’s first maser just a few years previously. In 1958, Townes and his colleague Arthur Schawlow published a scientific paper describing their proposed laser design, including a laser cavity geometry that would eventually prove successful. They also filed a patent application to obtain protection for their laser.
The First Working Laser
But when Townes and Schawlow filed for their patent, they had not yet succeeded in building their proposed laser. They had discovered a workable geometry for their laser cavity. However, they hadn’t found the right laser medium, or the right way to excite it. Even at the time their patent was granted, in March of 1960, they had yet to build a working model.
But now that they had published their theoretical calculations and proposed cavity design, many other researchers were racing to discover the right components and build the world’s first working laser.
On May 16, 1960, that feat was achieved by Theodore Maiman and his colleagues. Maiman built his laser using a ruby crystal as the gain medium, which other prominent researchers had dismissed as unworkable. He also excited the ruby medium with a flash of light, rather than the continuous light source others were trying. Soon after the announcement of Maiman’s laser, several other types of lasers were invented and constructed.
Thanks largely to the work of Townes, Schawlow, and Maiman, innovation on the laser was progressing rapidly. However, the questions of who had really invented the laser, and who was entitled to a patent on the laser, were far from settled.
The laser patent awarded to Schawlow and Townes, shortly before the debut of Maiman’s laser, was challenged by a researcher named Gordon Gould, who claimed he had invented the patented laser cavity first. In fact, Gould had even applied for a patent on a laser having this cavity himself. However, he filed his application months after Townes and Schawlow filed theirs.
Although Gould contended that he had come up with the key laser cavity geometry before Townes and Schawlow, he hadn’t immediately applied for a patent because he mistakenly believed that he could not do so until he had a working prototype. Even so, Gould believed his research notebooks could prove that he had been the first to devise the crucial cavity geometry. On this basis, he argued that he was legally entitled to the patent instead of Schawlow and Townes.
Under present-day U.S. patent law, Gould’s claim that he had been the first to invent the laser cavity in question wouldn’t help him. Since 2011, the first inventor to file their application is the one who is entitled to the patent (provided the application meets all other patentability requirements).
In the 1960s, the law was different, using a “first to invent” scheme rather than today’s “first to file.” Gould’s attempt to prove he had been first to invent the laser kicked off a series of legal proceedings that would last decades. Ultimately, the court found that Gould’s notebooks didn’t include enough information to prove that he’d developed the critical concepts before Schawlow and Townes. Nevertheless, Gould did eventually obtain other laser-related patents. Several of his patents covered common laser applications and widely used methods of exciting a laser medium, and thus proved enormously valuable. Better still, he was the first person to use the word “laser” at all (Townes and Schawlow referred to their device as an “optical maser”). It’s hard to put a price on that.
Issues of patents and inventorship are a big part of the history of the laser as it’s remembered today. If Gould had realized he didn’t need to build a working laser before patenting his design, he might have been granted the first laser patent. And his legal battle over the patent wouldn’t have been possible today – under the present-day patent system, the patent goes to the first inventor who filed for it, no matter who invented it first.
Even though patent laws have changed in some important ways since Gould, Schawlow, Townes, and Maiman were pioneering the laser, timing is still critical for anyone filing a patent application. If you’re thinking of applying for a patent, be sure to talk to your IP attorney or contact us to discuss the best way to move forward.
Blog Post © 2019 Kolitch Romano LLP
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DISCLAIMER: This article is intended to give the reader an overview of the topic, and does not constitute legal advice as to any particular fact situation. Facts matter, and every situation is different. In addition, laws and their interpretations change over time and the contents of this article may not reflect these changes. You are strongly advised to consult competent legal counsel regarding your particular situation.