In the decades since the 1960s, lasers have transitioned from a science fiction concept to a common tool used in various fields, no longer a rare or expensive item found only in research labs.
November 14, 1967 – Theodore Maiman Files Patent for the World’s First Laser
The Ruby Laser, a solid-state laser, was first created in 1960 by American physicist Theodore Maiman at Hughes Laboratory in Malibu, California. This is considered the world’s first laser, and Maiman filed a patent for it on November 14, 1967. The ruby is made from aluminum oxide mixed with chromium. When chromium absorbs green and blue light, it exclusively emits pink light.
The actual image of the ruby laser.
Laser is an acronym for Light Amplification by Stimulated Emission of Radiation, meaning “amplifying light through stimulated emission.” Natural and conventional artificial light is emitted by energy transitions at atomic and molecular levels without external intervention. However, a second type of light exists, occurring when an atom or molecule retains excess energy until compelled to release that energy in the form of light. Lasers are designed to produce and amplify this forced light into intense, focused beams. The unique properties of laser light make laser technology an essential tool in nearly every aspect of daily life, including telecommunications, entertainment, manufacturing, and medicine.
Albert Einstein played a pivotal role in the development of lasers by recognizing the potential for two types of emission. In a paper published in 1917, he was the first to propose the existence of stimulated emission. For many years, physicists believed that spontaneous emission of light was the dominant and most feasible form, and any stimulated emission would necessarily be much weaker. It wasn’t until after World War II that researchers began searching for the necessary conditions for stimulated emission to prevail, allowing one atom or molecule to excite another, creating the effect of amplified light emission.
Theodore Maiman – the father of the world’s first laser.
Electrons exist at distinct energy levels within an atom. These energy levels correspond to specific orbits of electrons around the nucleus. Outer electrons possess higher energy than those inside. When physical or chemical interactions occur from the outside, these electron particles can jump from lower energy levels to higher ones and vice versa. These processes can generate or absorb light (photons) based on Einstein’s hypothesis. The wavelength (and thus color) of the light depends on the energy difference between the levels.
Lasers are modeled after masers, devices that operate on a similar principle but produce microwave radiation instead of light radiation. Maser stands for Microwave Amplification by Stimulated Emission of Radiation, meaning “amplifying microwaves through stimulated emission.” Both masers and lasers operate similarly, differing only in the frequency of photons they utilize, with masers working in the microwave region and lasers operating in the ultraviolet, visible, or infrared spectrum. The first maser was created by Charles H. Townes, with assistance from two recent graduates, J.P. Gordon and H.J. Zeiger, in 1953. That first maser did not produce continuous waves.
At the same time, two Soviet scientists Nikolay Gennadiyevich Basov and Aleksandr Mikhailovich Prokhorov independently worked on quantum oscillation and created systems that could emit continuous beams using more than two energy levels. This system could emit continuously without dropping particles to their normal energy levels, thus maintaining frequency. In 1964, Charles Townes, Nikolai Basov, and Aleksandr Prokhorov were awarded the Nobel Prize in Physics for foundational work in quantum electronics, leading to the development of oscillators and amplifiers based on maser-laser theory.
The ruby laser created by Maiman emitted intense red light pulses with a wavelength of 694 nanometers in a narrow, highly concentrated beam, quite characteristic of the properties exhibited by many lasers today. The first laser used a small ruby rod with silver-coated ends to reflect light, surrounded by a spiral flashlamp, and was small enough to hold in one’s hand. Interestingly, the photographer commissioned by Hughes Laboratory to promote the new invention thought the actual laser was too small and photographed Maiman with a larger laser that ultimately did not function. The photo of Maiman with that “more impressive” laser has since been circulated and used in many publications.
Description of the ruby laser.
The presence of lasers in science fiction works or action films, along with general commentary, often leads to misconceptions. For example, contrary to depictions in movies like Star Wars, laser beams are never visible in a vacuum, as there is no scattering of light in a vacuum. In the atmosphere, laser beams can collide with dust or obstacles along their path and scatter, creating bright flashes; similar to how sunlight shines in a dusty environment. This effect can be applied to visible laser beams, such as for photography, by increasing the number of particles in the air, like using air freshener sprays.
High-intensity laser beams can be seen in the air due to Rayleigh scattering or Raman scattering. For beams with higher intensities focused on a small point, air can be heated to a plasma state, allowing the laser to be seen due to radiation from this plasma. However, the sudden increase in pressure when air is rapidly heated can create a loud explosion, potentially damaging the laser equipment (depending on the laser’s design). In science fiction films, special effects often depict laser weapons traveling several meters in a second, contrary to the fact that laser beams move at the speed of light, so fast that one cannot perceive the movement of the laser beam. Some scenes portray security systems using red lasers that can be disabled by characters using mirrors, as they see the laser beam by scattering white dust into the air. In reality, security systems may use infrared lasers instead of visible lasers.
Ruby laser cutting steel.
Since the 1960s, lasers have become more than just a science fiction concept or a rare, expensive item. They have evolved into a valuable tool in certain scientific applications, becoming essential in daily tasks and so commonplace that they can be purchased at grocery stores, with some people using them to measure room dimensions for wallpapering. Any list of significant technological achievements of the 20th century would prominently feature lasers. The integration of lasers into all aspects of contemporary life can be best assessed by the range of applications for laser technology. On one end of this spectrum are military applications, including the use of lasers as weapons against missile attacks. On the other end are everyday activities like listening to music on CDs and printing or copying documents. Laser pointers that sell for hundreds of dollars are considered inexpensive accessories, with carpenters using lasers, and simple measuring tools also equipped with lasers.
