Laser Introduction

Light Amplification by Stimulated Emission of Radiation, or LASER as it is commonly known.

The laser concept was first introduced by Albert Einstein in 1916. He found that electrons, when stimulated by light (energy), reach higher energy levels on excitation and then release energy excess energy as light, which we call laser.

The core component of a laser is a gain medium (liquid, gas, or solid) whose electrons get excited by energy and a light amplification process occurs. The gain medium gets energy from pumping, usually an external flashlight or another light source, powered by electricity.

When the atoms in the gain medium absorb energy from the pumping source, they reach an excited state. These excited atoms then release particles of light called photons. These photons are all of the same wavelength, which gives the laser light its unique color (if it’s in the visible spectrum).

Inside the laser, two mirrors are facing each other on either end of the gain medium. One mirror is a high reflector, meaning it reflects almost all the light that hits it. The other is an output coupler, which is partially transparent.

The photons released by the excited atoms bounce back and forth between the two mirrors. Each time they pass through the gain medium, they stimulate more excited atoms to release more photons. This process amplifies the light. Eventually, the light becomes intense enough to pass through the output coupler as a concentrated beam of light, what we call a laser beam.

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With all of this in mind we can now say lasers can be categorised in three main ways, gain medium, mode of operation, and wavelength.

The three main gain medium lasers are diode (semiconductor), fibre (fibre optic cable), and CO₂ (gas). You can also get solid state (usually rare-earth doped silica) or liquid lasers (usually a liquid dye solution) too.

The two main mode of operation lasers use continuous, or pulsed waves. Continuous-wave (CW) lasers emit a constant, unbroken beam of light as long as they are powered. There is no interruption or modulation in the light output. Pulsed lasers emit light in short bursts or pulses.

The three main wavelength types of laser are Ultraviolet, Visible, and Infrared and have a broad range of uses.

xTool summarises this introductory article quite well with the following:

Laser technology is a dynamic and constantly evolving field, with the potential for new types and advancements emerging in the future. Given the complexity and variety of lasers available, classifying them is necessary to understand their characteristics and applications.

In this article, we have explored common classifications and the popular types of lasers within each category. Among these, fiber, CO2, and diode lasers are particularly noteworthy for their widespread use and versatility.

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The main consideration when looking to purchase a laser is to research which one will cover most of what you want to achieve and within budget. There are many samples out there and without branding we elected to go with a diode laser as our first foray in to the fascinating world of laser.