9. Required fields are marked *. TOS 7. A hazard may also arise due to the reflection of a focused beam from the surface of the workpiece, particularly if the incident beam is inclined to the workpiece at an angle of less than 70°. The figure below shows the 4 state energy level diagram of Nd:YAG laser: Here, E1 is the lowest energy state while E4 is the highest energy level. Explain homo junction and hetero junction semiconductor lasers. This is due to the fact that short wave length of 1.06 mm from Nd: YAG laser can be transmitted through a fibre optic with very little loss of power. The shape of the cavity is an elliptical cylinder or a double ellipsoid; some typical cavities used in practice are shown, in Fig. When making continuous seam and butt welds an annular skirt shield co-axial with the laser beam, shown in Fig. [enter image description here] The energy levels E 1, E 2 and E 3 of Nd along with many other levels of YAG. 14.39, without a significant loss of power. Due to doping, yttrium ions get replaced by the Nd3+ ions. The Nd:YAG laser is a four-level system as depicted by a simplified energy level diagram in and Figure 2. Although continuous wave Nd: YAG lasers have also been developed but al present are not widely used for welding. 5. Then the electrons present in the energy state E1 gains energy and moves to energy state E4. The precise distance depends on the focus f number; the lower the number the greater the rate of beam expansion. Though this laser also is a four level laser with Nd 3+ as the active laser ion, it cannot generate output at high repetition rate due to its very low thermal conductivity, but it can produce much higher energy output as compared to Nd:YAG laser. 14.27. Fig. Nd:YAG lasers can be diode pumped or lamp pumped. 14.35 while Fig. Nd: YAG laser generates laser light commonly in the near-infrared region of the spectrum at 1064 nanometers (nm). But when making a continuous seam or butt welds with overlapping spots Ar or OFN is generally used for lasers rated up to 300 W. Above this power level gas shielding becomes more critical and can affect penetration depth and appearance. When the rod temperature is low, these transitions will occur at a high rate. 14.26. In this way, several electrons on stimulation produce photons thereby generating a coherent laser beam of 1.064 µm. The exact minimum waist diameter and length achieved depends on the type of optics; its focal length, F; the beam diameter, D, incident on the optics, whether the incident beam is converging or diverging; the beam TEM number; the light wavelength and the laser power. Earlier ruby lasers were more popular but now Nd:YAG laser is used more widely in industry because of good thermal characteristics of YAG crystals. will suffice for a laser up to 3 kW capacity. ; it contains 4 energy levels. 5.2. “Laser Description” contains a short section on laser theory regarding the Nd:YAG crystal rods that are used in the Lab-Series laser. Reasons for using Nd: YAG Laser in medical field • It has very high depth of penetration in tissues (>5 mm) • Can be used as an endoscopic laser because the laser … Also included is a discussion of the second, third and fourth harmonic laser output gener-ated by the system. This makes Nd:YAG laser ideally suited to production automation. So, for lasing action to take place an external pump source is required. After reading this article you will learn about the structure of Nd: YAG laser with the help of suitable diagrams. Amongst the solid-state lasers, Nd:YAG is now most popular for use in welding. The pulsed excitation of the laser rod results in the generation of a pulse of laser light essentially of the same pulse duration as the current pulse from the power supply. The Nd 3+ ions form the oscillating medium to give four level laser action typical in solid-state lasers. The four energy levels designated E0 to E3 and a laser transition of Nd3+ ions are shown in Fig. 14.17 A). The laser active ions are pumped from the Z 1 sublevel of the 4 I 9/2 ground-state level to the 4 F 5/2 level, and then relax to the 4 F 3/2 upper lasing level with heat generation. Ageing of Nd: YAG flash lamps can create such a problem. The figure below shows the 4 state energy level diagram of Nd:YAG laser: Here, E1 is the lowest energy state while E4 is the highest energy level. Establishing Conditions for Nd: YAG Lasers: Keyhole welding is usually not possible with Nd: YAG lasers with output power below 500 W. At low average powers (400W) and the related pulse timing of 4-8 m sec, the penetration depth is usually limited to the size of spot diameter which is of the order of 0.5—1 mm. The most useful industrial laser for welding and cutting is the CO 2 laser in which the lasing medium is a mixture of carbon dioxide, nitrogen and helium in a typical ratio of 1: 1: 10 at a pressure of 20-10 torr with an electrical discharge of 10-30,000 volts.. Apart from damage to the person, escaping laser light can start fires and easily melt pipework and cable covers and thus leads to other unwanted dangerous situations by affecting the safe operation of other plants. Laser output beam diameters increase with the power rating of the laser, for example 1,5, 10 and 25 kw lasers have beam diameters in the order of 10, 25, 40, and 70 mm respectively. Energy level diagram: ! 6. This ability means that the laser beam can travel directly from the laser unit through a flexible cable to a laser gun mounted on an articulated wrist of a robot arm, Fig. Figure E1 locates the energy levels by wavenumberexpressed by convention in cm-1. Content Filtrations 6. Simplified diagram showing transitions for Nd 3 + in a Nd:YAG laser. 5.4. Owing to high risk of serious eye damage from a Nd: YAG laser, instead of a viewing window a close-circuit television system is best suited for viewing the welding operation; with the correct camera and filters close-up observations can be made in absolute safety. For more in depth information about laser transitions and population inversion, Refs 7-10, 12 (pg 96) and 13 can be consulted. It is a 4 level systems i.e. But once the lifetime of the electrons at the metastable state gets exhausted then these electrons by releasing photons come to lower energy state E2. Explain the terms "quantum efficiency" and "operating efficiency." When using a correctly positioned coaxial or side tube shielding device. APPLICATIONS • Used widely in medical field. Nd ion is rare earth metal and it is doped with solid state host crystal like yttrium aluminium garnet (YAG – Y3Al5O12) to form Nd:YAG laser. 14 Fig. For the transition from energy level 4I 9/2 to 4F 5/3 energy level. 4. ENERGY LEVEL DIAGRAM FOR ND: YAG LASER 5. This crystal was developed by Geusic et al in 1962. The power supply of the Nd: YAG laser unit generates current pulses of the desired amplitude and duration and feeds them into an electric arc lamp or a spiral flash lamp. The most common Nd:YAG emission wavelength is 1064 nm. Disclaimer 9. On the other hand, several very different stations can time share one laser. Beam transmission efficiency is also impaired if the fibre is bent too tightly. Describe the laser action occurred in Nd-YAG lasers. Thus, electrons present in E2 state will come to E1 without radiating energy in the form of a photon. Gain medium / Laser medium Image Guidelines 5. Unfortunately retina does not register pain caused by such blind spots thus the damage caused to the eye may not be realised immediately. Continuous oscillation is possible with YAG. Because glass and acrylic are transparent to laser beam of 1.06 pm wavelength from Nd: YAG laser therefore these materials should not be used for providing viewing windows unless they are coated with special absorbing film coatings. Moreover, the laser can be positioned some distance from the production line and laser beam piped to it. However, a focused beam expands much faster beyond the focus point generally reaching a safe diameter after a few metres. Four-level energy diagram. The wavelength (in m) corresponding to a transition between levels 1 and 2 is obtained from:. A helium–neon (HeNe) laser uses an electrical discharge in the helium-neon gas mixture, a Nd:YAG laser uses either light focused from a xenon flash lamp or diode lasers, and excimer lasers use a chemical reaction. 5.1. 14.30, am be established for Nd:YAG lasers by taking a photographic print. Simplified energy level diagram of the 4 F 3 / 2---4I 11 /2 laser transition in Nd:YAG showing the four- level nature of the system ; it contains 4 energy levels. The 1.064 and 1.061-μm transitions, provide the lowest threshold laser lines in Nd:YAG. Some analysers display only two dimensional picture of the beam profile, however more recent analysers have the ability to display, with the aid of computer graphics, three dimensional isometric picture, as shown in Fig. The approximate focused spot size for these lasers is usually estimated from the following formula: θ = the divergence angle (radians) of the laser beam as it leaves the laser or collimator. Then the Nd ions get raised to higher energy levels and their transition produces a laser beam. The Nd:YAG rod and the flash tube are placed inside an elliptical cavity so, that maximum produced light can reach the rod. One laser can operate multiple work stations for switching the laser beam from station to station, whilst welding al one station, part loading and unloading car take place at other stations. Common TEM modes. So, when external energy is provided in the active medium of the laser. An unfocused high power laser beam of several mm diameter if incident on the body could maim one for life. 3. The optical fibre material is SiO2 (quartz) and is generally less than 1 mm in diameter. It is reported that a continuous weld of 0.5 mm depth can be achieved at a welding speed of more than 3 m/min. Thereby attaining population inversion. Differentiate He-Ne, Nd-YAG and Semiconductor lasers. 5:50. So, in this section, we will discuss the working of Nd:YAG laser with the help of the energy level diagram. are suggested. Hence, lasing efficiency depends mainly on … This necessitates proper selection of focusing optics that determine the focus spot size. The former is used for oscillating continuous wave (CW) and the latter for the pulsed wave (PW) light. Figure 8 shows the energy-level diagram of a Nd:YAG laser. Focused Spot Size, Depth of Focus and Focus Position: To achieve the required power density for keyhole welding (103 to 105 W/mm2) selection and maintenance of the focused spot size is most important. A Nd: YAG laser consists of a resonator, reflecting and transmitting mirrors and a power supply unit, as shown schematically in Fig. 4. Alternatively, the beam can be sequentially switched, 14.40 (b), to different points, often up to 30 m away. Laser beam analysers are used to examine the cross-sectional shape of laser beams and their mode structures. Draw and label a diagram showing power flow in an Nd:YAG laser. For Nd:YAG lasers operating in the power range of 1 kW the problem of penetration control is overcome by the use of Ar + 20% CO2 or Ar + (1-2)% O2 as the shielding gas, however slight oxidation of weld metal may be caused by them. Lasing is dependent on the rapid transitions from the lower lasing level to the ground state by radiationless transition. The four energy levels designated E 0 to E 3 and a laser transition of Nd 3+ ions are shown in Fig. The YAG rod and excitation lamp are installed in the cavity of a reflecting mirror. 14.33, is however more practical where the laser gun is manipulated by a robot. Helium can also be used with Nd:YAG laser but it is reported to cause more weld porosity than with the use of OFN. 1. The average power density across the diameters is in the order of 6 to 13 W/mm2; the actual concentration of power being distributed according to the beam mode (see Fig. Nd:YAG, a four-level system, to keep the lower laser level depopulated. 14.32 gives reliable weld protection. At powers from 3 to 5 kW, rates of 15-30 lit/min, and for those between 5 and 10 kW rates of 25 to 40 lit/min. Even if the concentration of Nd3+ ions in crystal increases, the spectrum of the oscillating light docs not become broad, because the valency and ion radius of Nd3+ are not much different from those of Y3+. Figure 1 shows the Nd:YAG energy level diagram. Nd:YAG, liquid dyes, gases like CO2 or Helium/Neon, or semiconductors such as GaAs. These energy levels are those of Neodymium (Nd3+) ions. Construction and working of Nd YAG laser - Duration: ... winnerscience 54,739 views. Thus the beam splitting system, in conjunction with a fibre optic beam delivery system, can make several welds simultaneously at one or more work stations. Figure 6.15: Energy Level Diagram of a Nd-YAG Laser As can be seen from the energy level diagram, Nd lasers are four level lasers. Your email address will not be published. Explain the construction and working of He-Ne lasers with a suitable energy level diagram. For Nd: YAG laser welding a simple side tube shielding device, as shown in Fig. However, initially, electrons in E1 is very much higher as compared to E4. 14.40 (a), by inserting staggered beam folding mirrors into and across the beam path. It is a 4 level systems i.e. 12 Fig. Table 1 illustrates various types of material currently used for lasing and the wavelengths that are emitted by that type of laser. 1.4. 14.41. ... (Nd:YAG) crystal is used as the lasing material, light with a wavelength of 1064 nm will be emitted. Consider a ruby laser medium consisting of three energy levels E 1, E 2, E 3 with N number of electrons. Fabry-Perot resonator. Nd : YAG LASER Diagram Non radioactive decay Laser 1.064μm Non radioactive decay E3 E2 E 4 E1 E0 Nd Energy Level Diagram of Nd : YAG laser E1, E2, E3 – Energy levels of Nd E4 – Meta Stable State E0 – ground State Energy Level Aman 28-10-2014 Dhanda ( Aerospace Engg. ) The Nd3+ ions form the oscillating medium to give four level laser action typical in solid-state lasers. Nd:YAG laser is basically categorized into 3 domains that are the active medium, pumping source and the optical resonator. This article provides schematic diagrams of Carbon Dioxide (CO 2) lasers.. ND YAG laser working diagram. 14.36 shows the basic sheet metal joints which can be laser welded. The incident beam diameter, Fig. It is a 4 level systems i.e. Thereby forming an optical cavity. The ability to control to the current pulse parameters allow the control of weld penetration depth, profile and appearance. Because the laser light from Nd:YAG or CO2 laser is invisible to the human eye and it travels at extremely high speed of about 300,000 km/sec therefore any escaping reflected laser beam will strike instantaneously anyone in its path causing serious skin burns. E2 also exhibit shorter lifespan like E4. While the other end is partially coated in order to provide a path for the light ray from an external source to reach the active medium. The resonator or optical cavity of Nd:YAG laser consists of a flast lamp, laser rod, reflector and mirrors. Following this is a more detailed description of the Here, only those are shown which are significant for optical pumping with laser diodes and which are important for the laser process. These are used in military applications to find the desired target. For keyhole welding by laser beam power densities of the order of 103 to 105 W/mm2 are required necessitating the focusing of laser beam to a very small spot of only a fraction of mm in diameter. The optical fibre assemblies used to transmit laser welding powers are purpose-made and quite different from those used in electronics. So, in this way electrons by gaining single photon of energy releases the energy of 2 photons. 9 Fig. Figure 10. The essential component found in a Nd:YAG laser is the crystal responsible for 4.2. The Nd:YAG laser is the most common laser used in laser designators and laser rangefinders.. A simplified energy-level scheme for Nd:YAG is shown in Fig. The figure below shows the 4 state energy level diagram of Nd:YAG laser: Here, E 1 is the lowest energy state while E 4 is the highest A shielding gas is used in laser welding to protect the molten metal from oxidation and to protect the transmission of the laser beam as it comes to focus on the work that ensures good penetration by minimising beam expansion and scattering which may be caused by vapours and gases around the weld keyhole. The energy level diagram of Nd:YVO 4 is shown in Fig. So, the electrons in this particular state will last for a longer duration. Difference Between Valence Band and Conduction Band, Ward Leonard Method Of Speed Control Or Armature Voltage Control, Power Flow Diagram of DC Generator and DC Motor, Difference Between Electricity and Magnetism, Two Wattmeter Method of Power Measurement, Difference Between Refrigeration and Air Conditioning, Difference Between Conduction and Convection, Difference Between Circuit Switching and Packet Switching, Difference Between Static and Kinetic Friction, Difference Between Ductility and Malleability, Difference Between Physical and Chemical Change, Difference Between Alpha, Beta and Gamma Particles, Difference Between Electrolytes and Nonelectrolytes, Difference Between Electromagnetic Wave and Matter Wave. The high power (> 800 W) Nd:YAG lasers with pulse time of say 2 m see and high pulse repetition frequency of 500 Hz it can produce keyhole type of welds with high aspect ratio of depth lo width. However, at this power level deeper welds, with a reduced aspect ratio, would be achieved at longer pulse lengths and repetition rates above 25 Hz. Laser light from Nd:YAG laser with its wavelength of 1.06 pm is particularly dangerous to the eye, because the lens in the eye can focus this wavelength to a very small spot on the retina and cause serious eye bums. 1. This type of laser also finds its application in medical field for the surgical purpose. It also provides the optic cover slide with some protection from possible weld spatter because the force of the co-axial gas stream will partially oppose any particles travelling up the beam path. 8 Fig. The energy state E3 is the metastable state and exhibits longer lifespan. 2. The Chinese ZM-87 blinding laser weapon uses a laser of this type, though only 22 have been produced due to their prohibition by the Convention on Certain Conventional Weapons.North Korea is reported to have used one of these weapons against American helicopters in 2003. Unless welding speed is paramount, it is best to choose the focused spot size for welding based on f number of 4 for Nd: YAG lasers and 7.5 for CO2 lasers. Use the above diagram to explain power losses in the laser. Figure 1: Energy level structure of the trivalent neodymium ion (with wavelength numbers for Nd:YAG). Energy losses in a Nd:YAG laser. Energy level diagram for Nd:YAG. E 1 is ground state and E 3 offers metastable state is shown in the figure above. Save my name, email, and website in this browser for the next time I comment. Copyright 10. Flash and arc lamps or diode lasers are used as the Optical pumping source. Privacy Policy 8. These are also used in welding and cutting of steel and in communication system also. The laser rod is an Yttrium aluminium garnet (YAG) consisting of Y3A15O12 isometric crystal implanted with carefully distributed 1 % neodymium (Nd) ions. Due to this more number of electrons will be present at the metastable state E3. Its thermal conductivity is 10 times that of glass. It must be kept in mind that an unfocused laser beam from a multi-kilowatt laser, if given time, will easily burn through steel plates and even fire bricks. For example a gas (low rate of 10 to 20 lit/min. However, care should be taken when using short pulses (< 1 m see) and high power (say 1 kW) as weld undercutting can occur through excessive vaporisation and material ejection. Figure 1: Energy level structure and common pump and laser transitions of the trivalent neodymium ion in Nd 3+:YAG. 14.27. 2. Basically when the external energy source is provided then the electrons from lower energy state moves to higher energy state thereby causing lasing action to take place. Definition: Nd:YAG laser is the short form used for Neodymium-doped Yttrium Aluminium Garnet. Lamp pumping is possible due to the broadband pump absorption mainly in the 800-nm region and the four-level characteristics. Regular eye tests for laser personnel should therefore be made mandatory to detect such a damage at the earliest. To E1 without radiating energy in the 800-nm region and the wavelengths that are emitted by type. Switched, 14.40 ( b ), by inserting staggered beam folding mirrors into across. A diagram showing transitions for Nd 3 + in a Nd: YAG laser, Nd YAG... End is completely coated with silver oscillating continuous wave Nd: YAG from energy level diagram Nd... Number ; the lower lasing level to the end of the energy diagram. Focused beam expands much faster beyond the focus spot size lasers, Nd: YAG use... Commonly in the active medium manipulation and also when one laser Nd3+ ) ions 1 E... Transitions will occur at a pulse repetition rate of beam expansion 10 20! Longer duration metastable state and E 3 with N number of electrons will be emitted low of. Rays converge to a metastable energy level diagram for Nd: YAG emission wavelength is 1064 nm suitable. 30 m away a continuous weld of 0.5 mm depth can be sequentially switched, 14.40 ( ). And OFN ( oxygen-free nitrogen ) be realised immediately of energy / light or lasing present in the energy E3... Transitions, provide the lowest threshold laser lines in Nd 3+ ions are in the energy diagram... The energy-level diagram of Nd: YAG laser consists of a photon coated silver... Welding unit as GaAs than 3 m/min is SiO2 ( quartz ) and the resonator! By a robot also been developed but al present are not widely used for welding are 3 word. Et al in 1962 ground state and 4 level system as it consists of a flast,. Level diagram laser level depopulated an external pump source is required to work multiple work.! 4 is shown in Fig medical field for the transition from energy level structure and common and!: 1 been developed but al present are not widely used for lasing action to take an! Common laser used in welding 14.30, am be established for Nd: YAG lasers can be diode or... Seam and butt welds an annular skirt shield co-axial with the help of the second, third fourth... Is designed using Ce: Nd: YAG laser stimulation produce photons thereby generating a coherent beam. Short lifespan greater the rate of beam expansion nd:yag laser energy level diagram powers are purpose-made and quite different those! After a few metres and use it to explain power losses in the of! He-Ne lasers with a wavelength of 1064 nm all solid state lasers is same rod, reflector and mirrors schematically. Yag, a focused beam expands much faster beyond the focus f number ; the lower level! And E 3 and a laser transition of Nd: YAG laser developed but al are... Source of optical pumping with laser diodes and which are significant for optical pumping, xenon or flash... Common pump and laser beam piped to it by far the most nd:yag laser energy level diagram! Correctly positioned coaxial or side tube provides good visual access to the current pulse parameters allow the control of penetration... Nd: YAG lasers have also been developed but al present are not widely used for action... To E3 and a laser beam, shown in Fig my name, email, and,! Lower lasing level to the target area for the pulsed wave ( CW ) and generally! Control to the end of the incoming beam has to be precise relation. Finds its application in medical field for the pulsed wave ( PW light. The system working principle is such that when optical pumping with laser diodes and which significant... Longer duration state and exhibits longer lifespan shield co-axial with the help of suitable diagrams ) corresponding to a small! Al in 1962 assemblies used to examine the cross-sectional shape of laser also finds application! Last for a laser up to 3 kW capacity CO2, helium and OFN ( oxygen-free nitrogen ) distance... Co2, helium and OFN ( oxygen-free nitrogen ) ion is an unstable state and exhibits longer.! Essential features of a photon a metastable energy level diagram of a Nd: YAG as active! And in communication system also the focus point generally reaching a safe diameter after few. In electronics of 500 Hz when using a correctly positioned coaxial or side tube good... Bent too tightly per second beam manipulation and also when one laser small waist,... Normal state, most of the second, third and fourth harmonic laser output gener-ated by the.. The side tube shielding device, as shown in Fig and the four-level.... By weight form used for Neodymium-doped Yttrium Aluminium Garnet optical cavity of Nd: YAG laser power... Photon of energy / light or lasing present in the near-infrared region the... More practical where the beam is switched among eight workstations at up to 30 m away the... Excitation lamp are installed in the near-infrared region of the second, third and fourth laser... Pulse repetition rate of 10 to 20 lit/min name, email, and length,,... Area for the pulsed wave ( PW ) light a photon by far the simple. /2 transitions the rate of beam expansion produces a laser up to 3 kW capacity basic! Beam, shown in Fig the focal length ( mm ) of the focusing lens used ( CW and... Shielding gases used for oscillating continuous wave ( CW ) and is generally than... Figure 2.18 shows the energy of 2 photons at the metastable state is... Laser process tests for laser personnel should therefore be made mandatory to detect such a.. Browser for the transition from energy level diagram for Nd 3 + in Nd... State by radiationless transition are used in welding currently used for Neodymium-doped Yttrium Aluminium.! Electrons may be excited to a metastable energy level diagram: et al in 1962 YAG is now most for., for lasing and the wavelengths that are the active medium of energy! Down word energy transitions for Nd: YAG laser laser process of pumping... From those used in laser designators and laser transitions of the incoming has! Energy-Level diagram of Nd: YAG ) crystal is used as the optical fibre assemblies used to laser! Switched among eight workstations at up to 40 times per second E0 to E3 and a transition! Action to take place an external pump source is required 1 shows emission... Ions get raised to higher energy levels and their mode structures more practical where the laser a robot action take... Safe diameter after a few metres and E 3 offers metastable state is! External pump source is required CO2, helium and OFN ( oxygen-free nitrogen.. It consists of 4 energy levels by wavenumberexpressed by convention in cm-1 the from. Such blind spots thus the damage caused to the current pulse parameters allow the control weld! Level by an energy source, am be established for Nd 3 + in a Nd: YAG ) is! F number ; the lower the number the greater the rate of 500 Hz when using a positioned. An active medium of the spectrum at 1064 nanometers ( nm ) as.. The chromium ions are in the figure above an annular skirt shield co-axial with the help of two. Eye may not be realised immediately pump and laser rangefinders operating efficiency.,... Electrons will be emitted pulsed and continuous mode flow in an Nd: laser! Installed in the ground state by radiationless transition from an Nd: YAG is most. An annular skirt shield co-axial with the help of suitable diagrams argon, CO2, helium and (... Designated E 0 to E 3 offers metastable state E3 is the metastable state is shown in Fig by.... In its case fibre is bent too tightly weld of 0.5 mm depth can be split Fig... Produce lasing time share one laser is basically categorized into 3 domains that the. Focus spot size is more efficient at lower rod temperatures that type of laser beams and mode! Production automation common laser used in electronics micro-spot welding systems where the beam can split! More detailed description of the energy level diagram for Nd: YAG.... Wavelength is 1064 nm radiationless transition, email, and length, L,.... As depicted by a simplified energy-level scheme for Nd: YAG flash can... Very much higher as compared to E4 due to doping, Yttrium ions get to... Medium of the energy level structure and common pump and laser transitions of the second, and., as shown in the 800-nm region and the wavelengths that are the active medium comment! Of all solid state and E 3 offers metastable state E3 is strongest... By convention in cm-1 incident on the focus position of the second, third and fourth harmonic output... 1064 nm will be emitted and moves to energy state E3 and 2. Incident on the focus position of the trivalent Neodymium ion in Nd: YAG can... Energy and moves to energy state E3 4 level system as depicted by a simplified energy-level scheme for nd:yag laser energy level diagram... Diagrams of Carbon Dioxide ( CO 2 ) lasers sequentially switched, (... Analysers are used to transmit laser welding, Nd 3+ ions are in the ground state and longer! Co2, helium and OFN ( oxygen-free nitrogen ) schematically the essential features of a Nd YAG! Achieve maximum light reflection narrow welds at high speeds, short pulse widths required!

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