Ruby laser

A ruby laser makes bright red light.

It uses a pink stone called a ruby. A bright flash of light hits the stone. This gives the stone lots of energy. The stone then lets out a beam of red light.

This light comes in quick pulses. People use this red light to make art. It can also help doctors. Some lasers even drill holes in diamonds. It is a very special tool.

The ruby laser was the first working laser. Theodore Maiman built it in 1960.

This laser makes a deep red light. It works using a synthetic ruby rod. This rod is a solid crystal. Inside the crystal are tiny chromium ions. These ions are the part that makes the light.

To make the light, the rod needs power. A xenon flashtube sends a bright flash into the rod. This is called optical pumping. This flash gives the chromium ions a lot of energy. The rod sits between two mirrors. These mirrors form an optical cavity. The mirrors bounce the light back and forth. This helps the light grow into a strong beam.

Ruby lasers send out light in quick pulses. These pulses last about one millisecond. People use these lasers for many jobs. They can drill holes through diamonds. Artists use them to make large holograms. Some doctors even used them to remove tattoos. Today, other types of lasers often do these jobs instead.

A ruby laser is a special tool that makes a bright, deep red light. This light comes in quick bursts called pulses. These pulses usually last about one millisecond. This laser is a solid-state laser. This means it uses a solid crystal to create its beam. The crystal used is a synthetic ruby rod. Inside this rod, tiny chromium ions are spread out. Even though they only make up about 0.05% of the crystal, these ions do all the work. They are the part that absorbs energy and then gives off the red light.

To make the light, the ruby rod needs a lot of energy. This happens through a step called optical pumping. A xenon flashtube sends a very bright flash of light into the rod. This flash gives the chromium ions a huge amount of energy. The rod is placed inside an optical cavity. This cavity is made of two mirrors at each end of the rod. One mirror is fully reflective, while the other is only partially reflective. The mirrors bounce the light back and forth inside the rod. This process causes stimulated emission, which makes the light grow stronger.

History shows us how this amazing invention began. In 1958, scientists Charles Townes and Arthur Schawlow wrote about the idea of an "optical maser." They thought a laser could work using visible light. Theodore Maiman wanted to build one. He worked at Hughes Research Laboratories in Malibu, California. Many people thought using ruby might not work well. Maiman decided to try it anyway using a pink ruby rod. He used a rod that was 1 cm by 1.5 cm. On May 16, 1960, he successfully fired the first ruby laser.

There are many interesting facts about how these lasers behave. The red light has a wavelength of 694.3 nanometers. This light has a very narrow linewidth of 0.53 nm. In the early days, the ends of the rod had to be polished perfectly. They had to be flat within a quarter of a wavelength. In 1961, a man named R.W. Hellwarth invented q-switching. This method helps concentrate the light into a single, strong pulse. Later, in 1962, Willard Boyle made a laser that could produce a continuous train of pulses.

We can see how ruby lasers connect to many different jobs. One early use was for rangefinding in the military. Some people even built a ruby laser pistol to show students how it works. This pistol was strong enough to pop blue balloons. Because the red beam matches how diamonds absorb light, it can be used to drill holes through diamonds. Artists use them to create large holograms that can be a meter square. Doctors once used them for hair and tattoo removal. Today, many of these jobs use newer lasers, but the ruby laser remains a very important part of science history.

A ruby laser is a type of solid-state laser. It produces pulses of coherent visible light. This light is a deep red color. The wavelength of this light is 694.3 nanometers. Most ruby laser pulses last about one millisecond. This device is important because it was the first working laser ever made. It changed how scientists understand light and energy.

The mechanism of a ruby laser relies on a synthetic ruby rod. This rod serves as the gain medium, which is the material that amplifies light. The rod contains a dopant. This dopant consists of chromium ions suspended in a synthetic sapphire crystal. These ions make up only about 0.05% of the crystal. However, these ions are responsible for all the absorption and emission of radiation. To start the process, the rod undergoes optical pumping. This is when a high-energy light source provides energy to the atoms. Usually, a xenon flashtube is used for this purpose. The flashtube sends intense light into the rod to achieve a population inversion. This means more ions are in an excited state than a ground state.

Once the ions are energized, the light must be amplified. The rod is placed inside an optical cavity. This cavity is formed by two mirrors at the ends of the rod. In early designs, the ends of the rod were polished with extreme precision. They had to be flat to within a quarter of a wavelength. They also had to be parallel within a few seconds of arc. One end was silvered completely to reflect all light. The other end was only partially silvered. This allows some light to escape as the laser beam. The mirrors cause stimulated emission. This process makes the light oscillate and grow stronger as it bounces back and forth.

The history of the ruby laser began with the concept of an "optical maser." In 1958, Charles Townes and Arthur Schawlow published an article about this idea. They suggested a device could work in the visual or infrared spectrum. Theodore Maiman took up the challenge at Hughes Research Laboratories in Malibu, California. Some scientists, including Schawlow, were pessimistic about using ruby. They believed the energy required would be too high. Maiman disagreed and worked in secret. He used a pink ruby rod measuring 1 cm by 1.5 cm. On May 16, 1960, he successfully fired the first laser beam.

Since that first success, many improvements were made. In 1961, R.W. Hellwarth invented q-switching. This technique concentrates the laser output into a single, strong pulse. In 1962, Willard Boyle produced the first continuous output. He used a mercury arc lamp to pump a very small rod. This allowed scientists to study a continuous train of pulses. While early ruby lasers were used for research, they also had specific technical limits. They have lower conversion efficiency compared to other mediums. They also have lower repetition rates than modern lasers.

Ruby lasers have many notable applications. One early use was in military rangefinding. By 1964, they were the standard for this task. They were eventually replaced by Nd:YAG rangefinders. In industry, ruby lasers are used to drill holes through diamonds. This works because the red beam matches the diamond's absorption band. Holographers also use them to create large portraits. These holograms can be up to one meter square. The 694 nm light is often preferred over green light for these large images. In medicine, they were used for hair and tattoo removal. They were also used for scar treatments and to induce healing.

Today, ruby lasers are less common in industry and medicine. They are being replaced by more versatile tools like alexandrite and Nd:YAG lasers. However, they remain significant in scientific history. They were the first tool used to pump tunable dye lasers. They are still used in applications that require specific short pulses of red light. The original laser built by Maiman is still operational today. It was demonstrated again in 2010 at a symposium in British Columbia.