Optics 101

Ruby Laser – History, Properties and Applications

Topics Covered

Introduction
Laser Properties
Physical and Chemical Properties
Applications
References

Introduction

A ruby-laser is a solid-state laser that employs a synthetic ruby crystal as its gain medium. The first ruby laser was developed by Theodore H. "Ted" Maiman at Hughes Research Laboratories in 1960. It produces pulses of red visible light at a wavelength of 694.3 nm. The active laser medium, synthetic ruby is energized by optical pumping through a xenon flashtube.

In a ruby laser, a ruby crystal is formed into a cylinder. One end of the cylinder is placed with a fully reflecting mirror, and the other end is placed with a partially reflecting mirror. The cylinder is surrounded by a high-intensity lamp to provide a white light which triggers the laser action.

When the retina is exposed to direct or scattered ruby laser radiation, it has the potential to cause permanent damage to the eyes. Hence it is necessary to wear the ruby laser glasses that match with the wavelength and power of the operating laser.

Although several lasers have been discovered since Maiman's device, the ruby laser is still used, commonly in high speed photography and pulsed holography, and as a light source for medical and cosmetic procedures.

Laser Properties

Laser Properties
Laser type Solid
Pump source Electrical discharge
Operating wavelength 694.3 nm

Physical and Chemical Properties

Laser Properties
Chemical formula Al2O3:Cr
Crystal structure Cylindrical
Melting point 2040°C
Hardness 9
Thermal conductivity 46.02 W/mK
Young's modulus 345 GPa

Applications

Rangefinding is one of the first applications of the ruby laser. It was initially used to optically pump tunable dye lasers. It is rarely used in industry due to its low repetition rates and low efficiency.

Some typical applications of ruby laser include the following:

  • Laser metal working systems for drilling holes in hard materials
  • High-power systems for frequency doubling into the UV spectrum
  • High-brightness holographic camera systems with long coherent length
  • Medical laser systems for tattoo removal and cosmetic dermatology
  • High-power Q-switched system.

References

 

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