Ruby Lasers

A ruby laser is a red solid-state laser based on a synthetic ruby laser crystal as gain medium. Ruby is chromium-doped corundum (aluminum oxide, Cr³⁺:Al₂O₃). The first laser, demonstrated by Theodore H. Maiman at Hughes Research Laboratories in 1960, was a free-running flashlamp-pumped ruby laser emitting at 694.3 nm [1]. Optical pumping is possible in the green and blue spectral region.

Although many other solid-state lasers have later been developed, ruby lasers belong to the relatively few solid-state visible lasers; most others emit in the infrared spectral region. In contrast to other red lasers, such as helium–neon lasers, they are suitable for generating intense pulses.

Ruby belongs to the class of three-level laser gain media and therefore requires quite high pump intensities for producing laser gain. Nd:YAG, a prominent example for a four-level gain medium, is much easier to operate. In addition, the required green or blue pump light makes diode pumping similarly difficult as for titanium–sapphire lasers; it is possible, however, with blue laser diodes [2]. Mostly, ruby lasers are pumped with flash lamps, either in free-running mode (with pulse durations of the order of 1 ms) or with Q-switching for nanosecond pulses with correspondingly higher peak power. Quite high pulse energies (e.g. 1 J) can be achieved, although hardly in combination with high beam quality.

Ruby lasers were among the earliest practical laser systems and found wide application during the formative decades of laser science and technology. Their ability to generate intense, coherent light at a visible red wavelength, often in short, high-energy pulses, made them especially valuable in early experimental and applied work.

One of the most important applications of ruby lasers was in scientific research, where they served as reliable sources for studies in nonlinear optics, laser–matter interactions, and plasma physics. Their high peak power enabled experiments that were not possible with conventional light sources, including early investigations of optical breakdown and laser-induced plasmas.

Ruby lasers were also widely used in holography, particularly pulsed holography, where their short pulse duration allowed the recording of three-dimensional images of rapidly moving or vibrating objects without motion blur. This capability found applications in engineering analysis, materials testing, and fluid dynamics.

In rangefinding and LIDAR, the high pulse energy and good beam quality of ruby lasers supported early laser-based distance measurement systems, including military and geophysical applications. The visible wavelength simplified detection and alignment in these systems.

Medical and industrial uses also emerged, most notably in dermatology, where ruby lasers were employed for tattoo removal and treatment of pigmented skin lesions due to their strong interaction with melanin. In industry, they were used for alignment, drilling, and precision measurement tasks, though often on a limited scale.

Some Q-switched ruby lasers are used for laser drilling in diamond.

Although ruby lasers have largely been replaced by more efficient and versatile laser technologies, they remain historically significant. Their applications helped establish many of the foundational techniques and fields that continue to shape modern laser science and engineering.

For professional purchasing, our buyer's guide for ruby lasers explains additional buyer-oriented technical background and suggests selection criteria: Pulse energy, Pulse duration, Repetition rate, Beam quality, Coherence length, Beam profile, Flashlamp lifetime, Cooling requirements. It also lists 1 supplier of ruby lasers. Some of these show their product descriptions as sponsored content:

(Suggest additional literature!)