A flyback transformer (FBT), also called a line output transformer (LOPT) or high voltage transformer (HVT) is a special type of electrical transformer. It was initially designed to generate high voltage sawtooth signals at a relatively high frequency. In modern applications, it is used extensively in switched-mode power supplies for both low (3 V) and high voltage (over 10 kV) supplies.
That distance from the focusing lens where the laser beam has the smallest diameter. The point at which light rays refracted by a lens meet. The focal point on a focused laser beam is the point of highest energy concentration.
G-code is one of a number of computer code languages that are used to instruct CNC machining devices what motions they need to perform such as work coordinates, canned cycles, and multiple repetitive cycles. G-Code is the most popular programming language used for programming CNC machinery. Also eee CNC.
The active laser medium (also called gain medium or lasing medium) is the source of optical gain within a laser. The gain results from the stimulated emission of electronic or molecular transitions to a lower energy state from a higher energy state previously populated by a pump source.
Gas which is blown into the cut to clear away molten metals, or other materials in the cutting zone. In some cases, the gas jet can be chosen to react chemically with the workpiece to produce heat and accelerate the cutting speed.
A type of laser in which the laser action takes place in a gas medium.
CO2 lasers use a mixture of carbon dioxide, helium, and nitrogen. Most applications can be done using a standard, predetermined ratio of these gases. Some applications require pulses with high peak energy and rapid decay of the pulse tail. Increasing the volume of CO2 gives this result. Increasing the volume of nitrogen allows operation of a laser at lower than its normal minimum CW power level.
The pressure of the Assist Gas that is usually measured in pounds per square inch (psi). With oxygen, gas pressure can range from 15 to 50 psi. With inert gases, the gas pressure can range from 30 to 200 psi.
Lasers usually emit beams with a Gaussian profile. A Gaussian beam is a beam of electromagnetic radiation whose transverse electric field and intensity (irradiance) distributions are described by Gaussian functions.
For a Gaussian beam, the amplitude of the complex electric field is given by
r – radial distance from the centre axis of the beam
z – axial distance from the beam’s narrowest point
i – imaginary unit (for which i2 = − 1)
k – wave number (in radians per meter).
w(z) – radius at which the field amplitude drops to 1/e and field intensity to 1/e2 of their axial values, respectively.
w(0) – waist size.
E0 = |E( 0,0) |
R(z) – radius of curvature of the beam’s wavefronts
ζ(z) – Gouy phase shift. It is an extra contribution to the phase that is seen in beams which obey Gaussian profiles.
The corresponding time-averaged intensity (or irradiance) distribution is
where I0 = I(0,0) is the intensity at the center of the beam at its waist. The constant is defined as the characteristic impedance of the medium through which the beam is propagating.
Most glasses are not laser cut. They have a high absorptivity to CO2 laser light and demonstrate cracking along the edge cut due to the rapid thermal cycle associated with laser cutting. However, a laser can effectively cut quartz and heat resistant glasses.
A hard limit is a stop on the machine that prevents the machine from moving further in a given direction. Typically these are used to prevent the machine from moving beyond its physical limits. Also see Soft Limit.
Term used to describe the variation of a laser cut +/- to a predetermined target, usually measured in thousandths of an inch.
The SureTest® Circuit Analyzer takes only seconds to test each outlet and circuit under a full load. This test tool checks for various wiring conditions including: correct wiring, polarity reversal and no ground per UL-1436. A simple menu gives access to measurements of line voltage, voltage drop under a full load condition, ground-neutral voltage and line impedances. The ground fault circuit interrupter (GFCI) test is performed separately in accordance with UL1436 and disrupts the electrical supply if a functional GFCI is present.
The magnitude of radiant energy (light) per unit, such as time or reflecting surface.
An IP address is assigned to every computer on an Ethernet network. Like the street address for your home, an IP address identifies network computers. It helps traffic flow between computers because each one has its own IP address.
An IP address is formatted as a series of four values separated by periods:
Each value ranges from 0 through 255.
For your home or office network, the IP address is most likely assigned by the router, using something called DHCP. The router keeps track of every computer’s NIC and maps an IP address to the NIC every time the computer joins the network. In the end, all computers have a unique IP address, and the world is safe for local networking.
The IP address assigned to your PC on a network is a local address. Similar IP addresses are used on the Internet to identify domains and other resources. Those are Internet IP addresses, separate from your local address.
The router is assigned an IP address by your Internet service provider (ISP). That IP address is an Internet IP address. It’s shared by all PCs on your network.
Local IP addresses start with 192.168 and 10.0.
The IP addresses discussed here are IPv4 addresses. Because the number of unique IP addresses is limited, a second standard, IPv6, has been established. The IPv6 standard allows for many more addresses, which will help accommodate future growth of the Internet.
If the router doesn’t assign an IP address, one must be configured manually.
No two computers on the network can have the same IP address.
IP is often prefixed by the acronym TCP, as in TCP/IP. The TCP part stands for Transfer Control Protocol: It’s simply a set of rules for transmitting information on a network. Technically, TCP/IP refers to the methods and engineering as opposed to a specific address or value.
A groove, slit, or notch made by a cutting tool, such as a laser cutter or the width of a groove made by a laser cutting tool. The kerf is dependent upon the properties of the material being cut, the workpiece thickness, the lens focal length, and finally, the type of cutting gas used in the laser. Also see Cut Width.
Is an acronym for Light Amplification by Stimulated Emission of Radiation. A laser is a cavity, with mirrors at the ends, filled with material such as crystal, glass, liquid, gas or dye. It is a device that produces an intense beam of light with the unique properties of coherence, collimation and monochromaticity.
The buildup of the coherent wave between laser cavity end mirrors. In CW mode, the wave bounding back and forth between mirrors transmits a fraction of its energy on each trip; in pulsed operation, emission happens instantaneously.
Laser Power Supply Unit
A laser power supply contains a flyback transformer to provide high voltage to excite glass laser tubes. Some have integral low voltage DC power outputs and some do not. Also see Power Supply (PSU).
Laser pumping is the act of energy transfer from an external source into the gain medium of a laser. The energy is absorbed in the medium, producing excited states in its atoms. When the number of particles in one excited state exceeds the number of particles in the ground state or a less-excited state, population inversion is achieved. In this condition, the mechanism of stimulated emission can take place and the medium can act as a laser or an optical amplifier. The pump power must be higher than the lasing threshold of the laser.
The pump energy is usually provided in the form of light or electric current, but more exotic sources have been used, such as chemical or nuclear reactions.
An optic (either reflective or refractive) that causes rays of light to converge to a point. A lens is the optic used to focus a laser beam on the workpiece. Short focal length lenses provide narrow beam convergence angles, necessary to penetrate thick metal sections. Beam diameter is an important consideration in lens selection. Power density and depth of focus can change with differing beam diameters.
Master Oscillator Fiber Amplifier
The term master oscillator fiber amplifier (MOFA, MOPFA, or fiber MOPA) is a variation of the term master oscillator power amplifier (MOPA), meaning a system where the power amplifier is a fiber amplifier. The latter is usually a cladding-pumped high-power amplifier, often based on an ytterbium-doped fiber. The main attractions of such fiber-based power amplifiers are:
- A high output power can be achieved with a high power efficiency.
- The cooling system can be relatively simple.
- The beam quality can be high; it is often close to diffraction-limited.
- The gain can easily be as high as tens of decibels. For comparison, most bulk amplifiers, particularly those with high average output power, have a much lower gain.
- master oscillator fiber amplifier (fiber MOPA)
However, the use of fibers also has disadvantages:
- Various kinds of fiber nonlinearities can make it difficult to reach very high peak powers and pulse energies in pulsed systems. For example, a few millijoules of pulse energy in a nanosecond pulse system are already considered high for a fiber device, whereas bulk lasers can provide much higher energies. In single-frequency systems, stimulated Brillouin scattering (SBS) can severely limit the output power.
- Due to the high gain, fiber amplifiers are relatively sensitive to back-reflections e.g. from a workpiece. At high power levels, it is not easy to use a Faraday isolator for solving this problem.
- The polarization state is often undefined and unstable, unless polarization-maintaining fibers are used.
- It can be attractive to use a gain-switched laser diode as seed laser for a fiber MOPA. Such devices compete with Q-switched lasers, e.g. for application in laser marking. Their advantages partly lie in their flexibility concerning output formats: it is easy to modify not only the pulse repetition rate but also the pulse duration and shape, and of the course the pulse energy.
- A special aspect of MOFAs is that the saturation power even of a large mode area double-clad fiber is low compared with the typical output power. Therefore, the power extraction can be as efficient as in a fiber laser, even for relatively low seed powers.
Master Oscillator Power Amplifier
The term master oscillator power amplifier (MOPA) refers to a configuration consisting of a master laser (or seed laser) and an optical amplifier to boost the output power. A special case is the master oscillator fiber amplifier (MOFA), where the power amplifier is a fiber device. In other cases, a MOPA may consist of a solid-state bulk laser and a bulk amplifier, or of a tunable external-cavity diode laser and semiconductor optical amplifier.
Although a MOPA configuration is in principle more complex than a laser which directly produces the required output power, the MOPA concept can have certain advantages:
- With a MOPA instead of a laser, it can be easier to reach the required performance e.g. in terms of linewidth, wavelength tuning range, beam quality or pulse duration if the required power is very high. This is because various performance aspects are decoupled from the generation of high powers. This gives extra flexibility, e.g. when a gain-switched laser diode is used as a seed laser. Note also that it can be advantageous to avoid the presence of additional optical components such as wavelength tuning elements in a high-power laser resonator; with a MOPA architecture, one can place these in the oscillator, where they do not have to withstand high optical intensities, do not spoil the power efficiency, etc.
- The same aspects apply to other kinds of modulation, e.g. intensity or phase modulation: it may be advantageous to modulate the low-power seed laser, or to use an optical modulator between seed laser and power amplifier, rather than to modulate a high-power device directly. Slower power modulation may be done by adjusting the amplifier’s pump power, without significantly affecting e.g. the obtained pulse duration or wavelength.
- The combination of an existing laser with an existing amplifier (or an amplifier chain) may be simpler than developing a new laser with higher output power.
- The optical intensities are lower in an amplifier, compared with the intracavity intensities in a laser.
However, the MOPA approach can also have disadvantages:
- The complexity of the setup is higher.
- The wall-plug efficiency is often lower. However, it may also be higher, e.g. if that approach allows to remove lossy optical elements from the high-power stage.
- The resulting laser noise tends to be higher, since an amplified source can not reach the shot noise level (→ amplifier noise). Effects of drifts of the seed power may be suppressed, however, if the amplifier is operated in a strongly saturated regime.
- A MOPA can be sensitive to back-reflections, which are amplified again before entering the master laser. This feedback sensitivity can often be cured only by placing a Faraday isolator behind the amplifier. Particularly for high-power pulsed devices, this can introduce serious limitations.
MOPA architectures are also used for pulsed laser sources. In that case, the amplifier may be used as a reservoir of energy. If a pulse from the seed laser extracts a significant fraction of the stored energy, the effect of gain saturation is relevant: the amplifier gain drops during the pulse. This can lead to a deformation of the temporal pulse shape. In some cases, the pulse shape from the seed source is tailored so as to obtain the desired pulse shape after amplification.
A unit of wavelength, normally used to describe visble and ultraviolet light. One nanometer (nm) equals 1 x 10-9 meters. One nanometer also equals 0.001 micrometers.
A solid-state laser of Neodymium glass offering high power or short pulses, or both, for specific industrial applications.
solid-state laser of Neodymium:Yttrium-Aluminum Garnet, similar to the Nd:glass laser. Both are pumped by flashlamp. Beam transmission is via fiber optics. Power is up to 4,000 watts. The wavelength is 1.06 micrometers. Nd:YAG laser light can perform finer detail work and is better suited for work on highly reflective materials than CO2 laser light. Also see CO2 Laser and Nd:Glass Laser.
Part-on-part nesting capabilities optimizes material use, reducing material waste, and increasing cost-effectiveness. Stacking or nesting optimizes material and can significantly reduce cutting times.
An element of Gas Jet used for cutting. The nozzle is used to constrict and direct the assist gas to produce a columnar flow. The flow of gas serves to push the molten metal through the kerf. Nozzles vary in shape and exit orifice. (Common orifice diameters are 0.040" and 0.060".)
In certain laser cutting operations, coaxial oxygen is used to initiate an exothermic reaction to improve the cutting rate for thick metals. This means the oxygen actually does the cutting, with the reaction being maintained by the laser beam. See Gas Jet Assist.
The maximum power delivered in a laser pulse. Peak power is an important metric in laser safety as the higher the peak power of a pulsed laser, the more damage it can cause to a safety filter. Consider a laser that generates pulses with an energy of 100mJ (1 x 10-1 J). If the pulse duration is 200µs (2 x 10-4 S), the peak power is 1 x 10-1 / 2 x 10-4 equals 500 Watts. If the pulse duration were to reduce to 10ns (1 x 10-8 S), the peak power would rise to 1 x 10-1 / 1 x 10-8 equals 10MW (1 x 107 Watts).
An individual layer of a laminated material.
Polymers, or plastics, are divided up into two main groups, thermoplastics and thermosets. See Thermoplastics and Thermosets.
The ability to position a part to be laser cut within a degree of inches for the x, y, and z-axis. The positioning tolerance specifies how closely a component has to be placed relative to its ideal placement. The positioning tolerance measures the position of uncertainty between where a part is supposed to be placed or a cut to be made and where it actually occurs. See Repeatability Tolerance.
The rate of energy delivery. Power (or more correctly, radiant flux) is used to express the output of continuous (CW) lasers and is measured in Watts (W). One Watt is a Joule per second. The average power from a pulsed laser is the product of energy per pulse (in Joules) and pulse repetition frequency (in Hertz). For example, if a giant pulsed laser produces 10 pulses per second (i.e. 10Hz) and the energy of each pulse is 100mJ (1 x 10-1 J), the average power is 10 * 1 x 10-1 equals 1 Watt.
Laser output per unit area, such as watts per square centimeter (W/cm2).
Power Supply Unit
A power supply unit (or PSU) converts mains AC to various AC and/or DC voltages for the internal components of a device. Most use switched-mode power supplies. Some power supplies have a manual switch for selecting input voltage, while others automatically adapt to the mains voltage. See also Laser Power Supply (LPSU).
A discontinuous burst of laser, light or energy, as opposed to a continuous beam. A single burst of energy from a laser. A true pulse achieves higher peak powers than that attainable in a CW output. See CW.
The rate at which pulses are generated. Pulse frequency is expressed in pulses per second (Hz).
Time, expressed in fractions of seconds, in which energy is delivered. Application Report shows the electrical input pulse length, which corresponds to the half height of the leading and trailing edges of the optical pulse.
Laser which delivers energy in the form of a single or train of pulses. This provides higher power at shorter intervals and is most often associated with the burr-free cutting of stainless steel and other high-strength, hard-to-cut materials. See CW.
- Electrical modulation of a laser power supply to produce discreet pulses of energy at a given pulse length and pulse period (pulse repetition rate).
- Mechanical interruption of the laser beam by a rotating chopper, which alternately blocks or passes the laser beam.
- Acousto-optical modulation of the beam within the laser resonator, caused by a device generically called a Q-switch. See Q-Switch.
A device that has the effect of a shutter to control the laser resonator's ability to oscillate. Control allows one to spoil the resonator's "Q-factor," keeping it low to prevent lasing action. When a high level of energy is stored, the laser can emit a very high-peak-power pulse. See Pulsing.
The ramp test is a method for determining the optimum focal distance between your focusing lens and the material you're cutting. You can place a block of wood that has been cut at an angle (the ramp) on the bed then engrave a straight line up the ramp. The point where the burn size is the smallest is the focal point for your laser. Generally speaking, when engraving you will want the surface of the material to be at that height and when cutting you will usually want the center of the material to be at that height.
The return of light waves from a surface (mirror). See Reflectivity.
The measure of a materials' reflection of laser light. Highly reflective materials like copper and aluminum alloys are difficult to cut requiring reduced work speeds. See Reflection.
Deflection from a straight path, undergone by a light ray or energy wave, in passing obliquely from one medium (like air) into another (like glass) in which its velocity is different.
Measures the ability of a CNC controlled machine, like a laser cutter, to repeat the exact part positioning or cutting pattern within the stated amount of variance for each part placement or cut. The smaller the repeatability tolerance, the more uniform the cut parts will be. Often measured in ten-thousandths of an inch or even in microns — hundred-thousandths of an inch. See Positioning Tolerance.
Ruida DSP Controller
The Ruida series controllers are popular in many 50 watt and up Chinese laser engravers. They offer PWM laser power control and are quite advanced. These can be retrofitted into most lasers, even the K40, but require a higher level of technical aptitude to install as the connections will have to be configured manually and the control head will have to be flush mounted into the chassis.
The Ruida DSP ships with RDWorks which is also based off of CorelDRAW. LightBurn Software is the only other software known to work with the Ruida and it offers vast improvements over the shipped software. The cost of this controller is in the $300-$500 range. Some popular model numbers are RDC6442G, RDC6442GS, RDC6332G, RDLC-320A, and the R5-DSP (Rebranded for Lightobject).
Scalable Vector Graphics (SVG) File
SVG is an XML-based vector image format for two-dimensional graphics with support for interactivity and animation. The SVG specification is an open standard developed by the World Wide Web Consortium (W3C) since 1999.
SVG images and their behaviors are defined in XML text files. This means that they can be searched, indexed, scripted, and compressed. As XML files, SVG images can be created and edited with any text editor, as well as with drawing software.
All major modern web browsers—including Mozilla Firefox, Internet Explorer, Google Chrome, Opera, Safari, and Microsoft Edge—have SVG rendering support.
Software limit. A means of defining an area or boundary of motion for which the laser cutting machine cannot exceed. Typically these are used to define the cutting envelope in which the head can move without crashing into something. This is done in software, instead of hardware, so that it can be changed when you change your fixturing or setup, and so that the machine can warn you ahead of time before you attempt to do an impossible move. See Hard Limit.
Spot size is nothing but the radius of the beam itself and is technically not the same as the beam diameter. The irradiance of the beam decreases gradually at the edges. The distance across the center of the beam for which the irradiance (intensity) equals 1/e 2 of the maximum irradiance (1/e 2 = 0.135) is defined as the beam diameter.
The spot size (w) of the beam is defined as the radial distance (radius) from the center point of maximum irradiance to the 1/e2 point.
Gaussian laser beams are said to be diffraction limited when their radial beam divergence is close to the minimum possible value, which is given by
where λ is the wavelength of the given laser and w0 is the radius of the beam at the narrowest point, which is termed as the beam waist.
The ability of a laser system to maintain a beam with constant output characteristics.
Taper is the difference between the top profile of the laser cut verses the bottom profile of the laser cut. Typically, the laser cut width is narrower at the bottom than at the top.
An acronym for transversely excited atmospheric laser. This CO2 gas laser uses a transverse flow of gas and operates at higher pressures than other gas lasers, generally near atmospheric pressure. The result is a higher energy beam.
TEM is an abbreviation for Transverse ElectroMagnetic modes. This term is used to designate the cross-sectional shape of the beam.
A measure of a materials ability to move heat from one place to another. During laser cutting, the cut zone should be heated without wasting energy heating up surrounding workpiece material. Materials with high thermal conductivity, such as copper and aluminum, cutting is slowed down as heat escapes from the cut zone.
Polymers that can be repeatedly melted down and cast into new shapes. Thermoplastics include polypropylene, polystyrene, polyethylene, polyamide (nylon) and others.
Materials that cannot be remelted once they have been made into their initial shape. Epoxies, phenolic resins, and most natural rubber products are included in this category.
A traverse is normal machine movement without laser cutting. For example, a laser is traversing when moving the cutting head into position to cut.
Ultraviolet (UV) Radiation
Electromagnetic radiation with wavelengths from 180-400 nm
Excimer lasers and frequently tripled and quadrupled Nd:YAG lasers that are very precise and well suited for micromachining of polymer materials. See Polymers and Nd:YAG Lasers.
Conversion of a solid or liquid into a vapor. Lasers vaporize the metal or material they are cutting.