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This page provides easy-to-understand explanations of terms relating to laser marking.

A to C
A/O Q switch An acousto-optic method Q-switch that changes the refractive index of light by introducing ultrasonic waves.
Alignment beam An alignment beam is an auxiliary beam used to display the position of the laser beam and perform position adjustment.
Because the marking laser is a non-visible beam, adjustment is performed with the alignment beam, which can be visibly confirmed.
Aperture A device that allows only a specific diameter of laser light to pass through in order to refine the center of the laser beam.
AR coating AR is an abbreviation for Anti Reflection.
An AR coating is applied to the lens to prevent reflections that occur on the surface, thus improving the transmittance of the laser beam.
Attenuator An optical component or shutter that is used to adjust the intensity or power of the laser.
Beam diameter This signifies the diameter of a laser beam, but normally this specifies the value of the beam center at half its peak value.
Beam divergence An angular measurement of the increase in beam diameter of a laser beam as it leaves the oscillator.
Beam profile A graph of the power distribution seen when a laser beam is cross-sectioned.
Beam profiler Instrument to measure the distribution of intensity for laser beam.
Chiller A device that chills water and keeps it at a fixed temperature.
This is used as a secondary cooling device for water-cooled YAG lasers.
CO2 laser A laser that uses carbon dioxide as a medium and oscillates at a typical wavelength of 10.6 microns.
Used in processing machines and for marking.
Complete air cooling

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.

Continuous wave Oscillating a seamless, continuous laser beam (CW).

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D to F
Deep UV Light that is shorter than 200 nm and is difficult to propagate outside of a vacuum.
ArF (193 nm) and F2 (157 nm) excimer lasers fall under the category of vacuum ultra-violet light.
DPSS An abbreviation for Diode Pumping Solid State. Synonymous with LD pumped solid state laser.
E/O Q switch An electro-optic method Q-switch that changes the refractive index by introducing voltage.
End pumping A method where excitation light is irradiated and energized from the rear of the laser medium. Because the center of the crystal is excited, the excitation efficiency is good, and a high quality laser beam is created.
Energy output The amount energy over time (generally measured in Watts).
Feedback light Light that has bounced back and returned to the laser oscillator after the laser beam irradiated from the laser oscillator has hit the target.
Fiber laser A system that uses fiber for the resonator and creates an overlapping structure with fiber cladding that has been doped with Yb ions or other elements, after which it pumps laser diode excitation light inside.
First pulse suppression Suppresses the initial giant pulse that is emitted with a Q-SW laser.
Flash lamp pumping A method that uses a lamp for the excitation source of the solid-state laser that will serve as the laser medium.
Focusing lens A lens that collects and focuses light on the target surface via the lens itself or a combination of lenses.
F-theta lens

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.

Fundamental wave The wavelength of a laser beam as it has been oscillated from the laser medium. For YAG, the wavelength of the fundamental wave is 1064 nm.

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Galvanometer mirror The mirror attached to the Galvonometer scanner.
Galvanometer scanner A stepping motor that is used to make the laser beam perform scanning.
Its prominent feature is the ability to accurately control the angle of stop rotation.
Gas laser

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.

Giant pulse

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

Green laser A laser that oscillates green light with a wavelength in the vicinity of 532 nm.

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H to I
Harmonic generation

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.

High reflective mirror A mirror that reflects all light within the resonator.
Infrared light Non-visible light that has a wavelength longer than 780 nm.
Inner marking Transmitting the laser beam through a transparent object such as glass, to perform marking or processing on the inside of a transparent object.
Ion exchange Removes ions and impurities that are generated from the water used to cool some models of laser markers in order to maintain cleanliness.

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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.

Laser diode Lasers created using semiconductor materials.
Laser medium

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.

Laser oscillator Equipment that amplifies and oscillates a laser beam through stimulated emission from an excited state.
Laser processing

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

Laser trimming A working process where resistor materials are trimmed to regulated resistance values.
LD An excitation method that uses a Laser Diode for the light source that excites the laser medium.
LD pumping Using a Laser Diode excitation light source to pump light into a laser producing medium.
Longitudinal mode A state where laser beams of many frequencies are oscillated depending on the distance between resonator mirrors.

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M to O
M2 (M square) Specifies the quality, specifically the intensity distribution of the laser beam in the horizontal direction.
M2=1 is said to be the ideal single mode.
Multi mode A mode where the cross-section of light rays emitted from a laser oscillator appears as multiple peak points.
Optical isolator A device that possesses the ability to pass light in a single direction only. Used to block return light from a laser.
Output coupler

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.


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.

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Peak power The divided value of pulse energy and pulse width. W (watts).
Polarization plate An optical element that produces fixed-direction polarized light.
Power Amount of energy over time, in W (watts) units.
Power meter A device that measures the output of laser light.
Used to manage laser power attenuation conditions.
Protective goggles Safety goggles that are used to protect your eyes from laser beams.
Appropriate goggles are selected according to wavelength.
Pulse energy The amount of energy allotted to a single pulse from a pulse laser oscillator.
In J (joules) units
Pulse oscillation

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.

Pulse Stretcher The structure or member that stretches the pulse width of a laser beam.
Pulse width The irradiation time allotted to a single pulse from a pulse laser oscillator.
Pulsed wave Oscillation of laser light at a fixed frequency. Opposite of Continuous Wave.
Pumping Adding external energy to the atoms within the laser medium and changing from a low and stable state of energy to a high state of energy.
This high state of energy is called an excited state.
Purified water Water that has been chemically and physically treated to remove dissolved substances. Purified water is used for water-cooled laser markers because it is used as an insulator.

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Q to S
Q switch An optical component that places an absorber between the laser medium and output coupler and controls laser oscillation, creating high energy.
Resonator The area between the high reflective mirror and output coupler that is used to create a laser beam. Also called the cavity.
Scanning Scanning laser beams using a Galvanometer motor or other such device.
Second harmonic generation (SHG) Two times the frequency of a laser fundamental wave or 1/2 the fundamental wavelength. For a YAG laser 1/2 of 1064 nm indicates a wavelength of 532 nm (Green laser).
Seed laser The original light source.
Semiconductor laser

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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Short pulse laser Specifies a laser that oscillates at a pulse width of a picosecond or less.
* A picosecond is 1 trillionth of a second (10-12 seconds), and is expressed in PS units.
Shutter A light shielding plate used to block the laser beam.
Side pumping

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.

Single mode

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

Solid state laser A laser oscillator that creates a laser beam by irradiating the laser medium with a lamp, laser diode or other such light source.
Spatial mode A mode where the optical axis of the resonator is in a vertical direction. The cross-section of laser beam power distribution is expressed in single points in single mode, and appears as multiple-peak points in multi-mode.
Stimulated emission

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

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T to Z
Third harmonic generation (THG) Three times the frequency of a laser fundamental wave or 1/3 the fundamental wavelength. For a YAG laser 1/3 of 1064 nm indicates a wavelength of 355 nm (UV laser).
Threshold The limit value of a response occurring after energy has been added to a substance. Also known as "Threshold Value".
Transverse mode Can capture the power distribution of light rays emitted from the laser oscillator in cross-section.
Ultra-violet light Non-visible light that has a wavelength shorter than 380 nm. Due to this wavelength being an effective disinfectant, it is used in food and medical related fields.
Visible light

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".

Wave length The cyclical length of waves (wave motion) that are transmitted through the air.
YAG Yttrium Aluminum Garnet (Y3Al5O12). One type of solid-state laser medium.
It is often used as an industrial laser and supports marking on metals and plastics.
YAG laser A laser that has been oscillated by exciting a YAG crystal doped with an Nd ion using a laser diode or lamp.
YVO4 An abbreviation of Yttrium Vanadate (YVO4), a type of medium used for solid-state lasers. Often used with the end pumping method.
Oscillates a fundamental wavelength (1064 nm) laser.
YVO4 laser A laser created by exciting an Yttrium Vanadate based YVO4 crystal doped with an Nd ion using an LD or lamp.
Znse Zinc Selenide. Used in CO2 laser lenses because it is an optical crystal that transmits far-infrared rays.

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