Glossary

An air-cooling method that uses radiator fins, fans, and Peltier elements, without using water to cool down the laser equipment.

As seen in the illustration to the right, a system where the laser heat generated by the laser oscillator is conducted by the Peltier element and cooled using air, without the use of cooling water.

A correcting lens that condenses a laser beam polarized by a polygon mirror onto a planar surface to make the scan speed constant.

Features of a f-theta lens include
"Constant speed scanning anywhere on the surface of the workpiece".

[Equation for an f-theta lens]

With a lens that is designed so that the relationship between the image height, h, and the entry angle, θ, is equal to [h=fθ], the scanning speed on the surface of the workpiece is constant.

A laser system in which high voltage is arced through a gas mixture sealed inside of a tube, and then discharged, changing the gas to plasma.
Commonly used gases include CO₂ (carbon dioxide) and He-Ne (helium-neon).
Helium-neon lasers are used as a light source in opto-electronics and CO₂ lasers are used for marking and processing.

*The optimal laser will differ depending on the desired processing application.

A pulse that possesses high-energy amplified via Q-switch.

In general, the shorter the wavelength of the laser, the higher the energy and the greater the absorption rate for the object (target). For example, a copper plate (Cu) using a fundamental wavelength (1064 nm) can only absorb at a rate of about 10% and is a material that is difficult to mark. However, at half the wavelength (532 nm), the absorption rate increases to around 50-60%.

[How Green Lasers and UV Lasers Are Created]

Green lasers are referred to as second harmonic generation. A fundamental wavelength is passed through an oxide single crystal (LBO: Lithium Borate) and at a conversion rate of about 30 to 40% is converted to a wavelength of 532 nm.
The converted light at a wavelength of 532 nm is combined with fundamental wavelength light and is further passed through a single crystal, which converts it into a UV laser (wavelength: 355 nm). Also, fourth harmonic generation is referred to as D (Deep) UV, with a wavelength of 266 nm.

An abbreviation of Light Amplification by Stimulated Emission of Radiation. Lasers have the following qualities: (1) Monochromaticity - A pure, single wavelength of light. (2) Excellent directionality - A parallel beam that advances without spreading.
(3) High coherence - Uniform light phases.

A comparison of ordinary light and laser light

Lasers emit beams of light with high directivity, which means that the component light waves travel together in a straight line with almost no spreading apart.
Ordinary light sources emit light waves that spread apart in all directions.
The light waves in a laser beam are all the same color (a property known as monochromaticity). Ordinary light (such as the light from a fluorescent bulb) is generally a mixture of several colors that combine and appear white as a result. As the light waves in a laser beam travel, they oscillate with their peaks and troughs in perfect synchronization, a characteristic known as coherence. When two laser beams are superimposed on each other, the peaks and troughs of the light waves in each beam neatly reinforce each other to generate an interference pattern.

The source material that produces the laser. Types include gases, liquids, as well as solids, and it is possible to extract laser beams with different characteristics for each type.

Processing performed using a laser.
Primary applications include micro-processing, welding, marking, and cutting.

The mirror that passes an emitted laser beam that has been amplified within the resonator.

Oscillation Environment

In laser oscillation, a state where "the number of high-level atoms is greater than the number low-level atoms" is called population inversion.

Structure

The structure of a gas laser oscillator seals gas in. It is also equipped with an electrode that produces the charge needed in order to generate population inversion and has optical resonators installed on both sides of its tube.

Oscillation Principles

When a rated electrical current is passed through the laser tube and discharged, it creates strong plasma within the tube and that plasma collides with other atoms to create an excited state. Between optical resonators constructed from a pair of reflective mirrors that possess extremely high reflectivity for the wavelength of the laser, the light is amplified as it goes back and forth, and is reflected on one side of a reflective mirror whose reflectivity is around 99%, resulting in the external emittance of laser light.

Oscillation involving a laser light that is produced in flashes. Pulse oscillation controls laser output by changing the oscillation frequency, making it possible to increase the amount of energy per single pulse. The values that express laser output are average output, peak output, and pulse energy. Their units are W (watts) and J (joules). Compared to the output value of a continuously oscillating laser, the peak output value for a pulse laser is high. However, average output is a number value that has added the oscillation frequency to the product of pulse width and peak output, making the average output power low. Even when the average output is a few W (watts), the peak energy of a pulse laser is +10 kW (kilowatts). This gives pulse lasers energy to mark and process metals.

In short, a laser made using semiconductor material. The activation layer between the p-n junctions generates light when p-side holes combine with n-side electrons.

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A method where excitation light is irradiated and energized from the side of the laser medium.

A method of excitation by emitting excitation light from the area surrounding the side of the laser crystal. In this method, it is difficult to transfer heat to the center and heat cannot be transferred evenly to the whole medium.

A laser beam that has been collected to a single point in its cross section and has the characteristics of transverse mode points.

A phenomenon where excited atoms are hit with light, inducing photon generation and causing a chain reaction resulting in light emission.

Light that is visible to the human eye, measuring in wavelength from 380 nm to 780 nm.

What is Light?

Light is a type of "electromagnetic wave". "Electromagnetic waves" follow a standard of "wavelength" and starting from those of long wavelengths, can be divided into radio waves, infra-red rays, visible rays, ultra-violet rays, X-rays, and gamma rays.

What is Color?

As wavelengths of light hit an object, wavelengths that are reflected without being absorbed by the object are taken in by the human eye (retina). When this occurs, we recognize these wavelengths as the "color" of the object. The refractive index differs depending on the wavelength, therefore light is split. As a result, we are able to recognize a wide variety of "colors". For example, an apple reflects red wavelengths of light (600 to 700 nm) and absorbs all other wavelengths of light.
*Black objects absorb all light and thus appear black.

What is visible light?

The spectrum ranging from "red" to "purple" is referred to as "visible light". Also, longer wavelengths of light that are located in a region that is undetectable to the human eye are called "infrared light". Those on the shorter side are called "UV (ultraviolet) light".