Beam expander is a kind of optical system composed of two or more elements, it can adjust the size of laser beam and its divergent characteristics. Thus beam expansion reduces the beam divergence and enables the emission of very. The matrices for the multipleprism beam expanders are general and enable a. Both numerical analysis and experimental results are presented, showing that the fabricated lens has different optical powers in the two transverse directions and can collimate the divergent beam generated by a laser diode in the fastaxis direction with high energy efficiency. Beam expanders are required in most laser systems to change the diameter of the incoming source to match the requirement of the optical system. For a diffractionlimited gaussian beam, the 1e 2 beam divergence halfangle is. Beam diameter and beam divergences are two of the most important technical specifications to consider when choosing a laser. They are ideal for applications in which a small spot must be formed at some distance from the laser, or where the collimation range must be extended for illumination, or for alignment of distant objects. By expanding the beam within the system, the input beam diameter d is increased by a factor m, reducing the divergence by a factor m. A beam expander is any optical system designed to increase the diameter of a laser beam. Laser beam expander lens, laser beam expander lens suppliers.
Keplerian beam expanders are designed so that the collimated input beam focuses to a spot between the objective and image lenses, producing a point within the system where the lasers energy is concentrated figure 3. These compact beam expanders are optimized at a wide range of wavelengths for maximum flexibility, making them ideal for use with demanding tunable laser sources. Spherical reflectors as laserbeam expanders sciencedirect. In a laser beam expander, the placement of the objective and image lenses is reversed. Generally, the beam divergence of laser beam is measured using beam profiler.
When using the keplerian or galilean designs in laser beam expander applications, it is important to be able to calculate the output beam divergence. Compact beam expanders that do not sacrifice laser beam. Be sure to place any filter between the expander and the ccd so they will experience the lowest power densities. Cutting tools free delivery possible on eligible purchases. This shows the advantage of using beam expanders in laser optical applications. Beam expanders have two main purposes in the laser industry. These galilean beam expanders have threaded input and output apertures, which allow additional lenses and filters to be installed easily along the optical axis of the beam expander.
Laser beam expander 650nm red laser module longrange dot position indicator40mm extender laser beam expander description. Uslasers beam divergence calculator beam divergence calculator to check the beam divergence for any lens in milirads, input data into the wavelength and clear aperture boxes provided below. The laser was the first device capable of amplifying light waves themselves. To calculate the beam divergence and spot size of the given laser beam. Thorlabs reflective beam expanders use a pair of prealigned protectedsilvercoated spherical mirrors to provide 2x, 4x, or 6x beam expansion or reduction. Two different ways to expand your laser beamare you using. This integration results in narrow output beam divergence with fwhm of 7 and.
Doesnt matter if you just collimate your beam with a longer focal length larger diameter lens, or using a beam expander which can take the output of an already collimated laser beam and then expand it and focus back to infinity, either way the beam is being expanded further and will produce proportionally less divergence. When the beam is finally focused down to a small spot, this spot is a factor of m smaller. Unlike our transmissive beam expanders, they exhibit virtually zero chromatic aberration as shown in the left graph below, making them especi. Techspec divergent adjustable broadband beam expanders.
In the simple and frequently encountered case of gaussian beams, this means that the rayleigh length must be long compared with the envisaged. They utilise a three element design corrected for spherical abberation. Introduction beam expander is used to modify laser beam so that the original beam waist is increased in proportion to the ratio of focal lengths of the first and second lens. Edmund optics eo, the premier provider of optical components, introduces techspec da divergent adjustable fixed broadband beam expanders. Build your beam expander from aos standard mount products or ask us to produce a custom product to your requirements.
The beam divergence decreases and the onaxis intensity increases with increasing beamwidth. They are listed in order of increasing power and risk for biological damage see fig 2. The visible type can be mounted directly to any hene laser. A common type of device used for this purpose is a lens telescope in which a pinhole is placed at the common focal point of the two lenses. Laser beam expanders used in optics and photonics applications are available at edmund optics.
Laser beam expanders with diopter correction function belbed. In most cases, the term is taken to mean a telescope designed to take a smalldiameter collimated beam input beam and produce a larger diameter collimated output beam, thus reducing the divergence of the beam. Maiman at hughes research laboratories, based on theoretical work by charles hard townes and arthur. Beam expanders thorlabs galilean type beam expanders, which are available in both fixed and variablemagnification options, are offered for use in the uv, visible, near infrared, and midinfrared spectral ranges.
When deciding upon a beam expander, it is the beam diameter at the position of mounting the beam expander which is important. The gaussian beam is a transverse electromagnetic tem mode. The mathematics of gaussian beam laser modes, is very interesting stuff, and quite fun to work with was for me anyway. Optical performance is optimized first with inhouse design and also with system test metrology. High cw damage threshold makes this ideal for cw laser processing applications. The term laser originated as an acronym for light amplification by stimulated emission of radiation. At maximum range, the beam expander makes it possible for you to pinpoint whatever you like, without losing the sharpness of. They utilise a three element design corrected for spherical abberation with a design performance of lambda4. Jul 21, 2016 beam expanders are required in most laser systems to change the diameter of the incoming source to match the requirement of the optical system. This enables a compensation of the inherent laser divergence and an optimal collimation. Variable beam expanders industrial laser solutions.
Every beam expander from sill optics has a mechanical or electrical divergence adjustment available. The two basic configurations used for these afocal systems are the galilean and the keplerian telescope types, shown in figs. This work is used to determined and reduce the divergence angle of hene laser with and without beam expander. Nov 18, 2015 newport demonstrates how to assemble both a galilean and a keplerian beam expander using standard nbk7 lenses and the alinetm selfaligning lens mount system. In other words, if the output of the beam reducer is three times smaller, it will be also be three times more divergent. The laser light amplification by stimulated emission of radiation is a. While a variety of offtheshelf beam expanders are available, occasionally these standard beam expanders may not meet your application needs. When used as intracavity beam expanders, in laser resonators, these telescopes. By expanding a beam prior to focusing, smaller focal spot sizes can be achieved. Motorized laser beam expanders and reducers mex 4lasers. Rp photonics encyclopedia gaussian beams, laser beam. How to design your own beam expander using stock optics. These beam expanders are light weight and short bodied and because they are galileo type design, they have little aberration and correction.
What i need is not just collimating, but to focus laser beam waist become smaller then the original at a distance. They feature diffractionlimited performance with a. All beam expanders feature aos worldclass quality aspheric optics and precision alignment mechanics. The applications of the beam expanders lenstek laser optics. Beam expanders for co2 lasers lens systems laser components. It provides variable magnification of 1x to 3x and 2x to 8x with adjustable focus to correct for laserbeam divergence. Why a larger beam results in a smaller spot size in laser designation. The reflective design of these beam expanders is achromatic and with aluminium coatings can operate from uv to far ir without adjustment. My project is to make a laser beam expander so that a laser beam can be focused far away from the source. Motorized laser beam expanders mex series used to increase laser beam diameter and adjust divergence. Beam expanders aperture optical sciences optical components. Beam expanders consist of two lenses that are built according to the galileo principle and therefore do not generate an intermediate focus. Design and advancement status of the beam expander.
Most diodes have a lens mounted close to the laser chip and this will capture most of the light and make the beam almost straight. Gaussian beams are usually considered in situations where the beam divergence is relatively small, so that the socalled paraxial approximation can be applied. Beam divergence is a major issue when using an excimer lasermost beams exit with rectangular dimensions of about 25. This is a common misconception taught in beginning physics classes or in the popular press. The ratio of the bpp of the real beam to that of an ideal gaussian beam at the same wavelength is known as m 2 m squared. Request pdf divergence of farinfrared laser beam and collimation for. Does a laser beam converge and diverge without lens. To a laser physicist, seeing pencil laser beams propagate planetary. Yag 1064, 532, and 355 nm and 800 nm laser sources. All real laser beams have m 2 values greater than one, although very high quality beams can have values very close to one. Thorlabs galilean type beam expanders, which are available in both fixed and variablemagnification options, are offered for use in the uv, visible, near infrared, and midinfrared spectral ranges. Integration of a diode laser and a beam expander results in a simple and cost. Inp based multiple quantum well lasers with an integrated tapered.
These systems are suited for typical medium power levels of up to. Compact beam expanders that do not sacrifice laser beam diameter. Beamexpanders for co2 lasers ulo optics laser optics. The angular convergence for both configurations is. If i wanted a focusable green laser, but i really liked a certain nonfocusable one, is there a universal beam expander i can buy. Rp photonics encyclopedia collimated beams, divergence. The mathematical expression for the electric field amplitude is a solution to the paraxial helmholtz equation. This approximation allows the omission of the term with the secondorder derivative in the propagation equation as derived from maxwells equations, so that a firstorder differential equation results. Special optics high power beam expanders are specifically designed with a convex first surface, which diverges the return reflection from the first lens surface and prevents any damage backstream of the beam expander. Yag and yb doped fibre lasers operating near the 1. However, spreading of a laser beam is an inherent property of the beam due to the uncertainty relationship as well.
However, since most laser is slightly divergent, the beam will not be emitted by parallel beam. Sometimes the active laser medium, will have brewster angle end mirrors, which render the laser plane polarized, and then the actual laser resonator mirrors are external, so operate in air. A laser beam expander is designed to increase the diameter of a collimated input beam to a larger collimated output beam. Obviously beam diameter is just the diameter of a laser beam, measured in millimeters. Why a small change in this specification greatly affects laser beam intensity. Divergence of farinfrared laser beam and collimation for galilean. Beam divergence is a major issue when using an excimer lasermost beams. Contemporary laser beam expanders are afocal systems developed from wellestablished optical telescope fundamentals. A collimated beam of light is a beam typically a laser beam which has a low beam divergence, so that the beam radius does not undergo significant changes within moderate propagation distances. A wide variety of laser beam expander lens options are available to you, such as spherical, aspheric, and plano. The term laser is the acronym for light amplification by stimulated emission of radiation. Two primary beam expander designs are used today, keplerian and. The compact zoom beam expander is designed primarily for nd. Our fixedmagnification, rotatinglens optical beam expander.
Laser beam expanders designed to use with high powered lasers that are made of lenses attached together without using glue airgap. These galilean beam expanders incorporate the highly regarded tropel optical designs with improved adjustability and mounting. Standard or custommade beam expanders have a unique mechanical closed loop slidinglens design ensuring high pointing stability and minimal dimensions. Any members here that sell beam expanders for any laser. A beam expander is a two or more element optical system that changes the beams size and divergence characteristics. We also offer variablemagnification beam expanders and reflective beam expanders. The fixedmagnification, slidinglens beam expanders are offered with optics that have either narrowband or wideband ar coatings. Laser beam expanders increase the diameter of a collimated input beam to a larger collimated output beam. Expander works with only the arctic, krypton and lunar sold separately. About 5% of these are lenses, 1% are laser cutting machines. In size restricted applications, it is desirable to use a compact beam expander but in most cases a compact beam expander is only suitable for small diameter beams. Expander 10x adjustable focus laser beam expander wicked.
Cw laser beam expanders galilean design works well for any visible or nearir laser system as a great general purpose beam expander. They are most often used to decrease divergence or to create smaller final focused spot sizes by expanding the beam before the final focusing element. Edmund optics has introduced its new zoom beam expander. A gaussian beam is a beam of electromagnetic radiation whose transverse electric field and intensity irradiance distributions. Beam expander focusing aleksandar marincic, adel rajhi elektrotehnicki fakultet, beograd 1. This means that the laser beams divergence is solely determined by the. A laser beam with a narrow beam divergence is greatly used to make laser pointer devices. Furthermore the beam can be focused convergent beam path, defocused divergent beam path systematically.
There is no such thing as a laser beam that does not diverge. It either diverges from or converges to this beam waist. The expander also has an adjustable focus, which lets you choose exactly how precise you want your laser to be at any given distance. Optical surfaces laser beam expanders incorporate offaxis mirrors which provide an unobstructed output and highly efficient transmission. Zoom beam expanders correct for laserbeam divergence.
These laser beam expanders can be used with cw and pulsed laser sources and incorporate large input and output apertures so as to produce diffractionlimited, expanded or reduced beams for a wide range of input beams. Beam expanders consist of transmissive configurations, with galilean or keplerian designs, and reflective configurations, which use a series of mirrors, similar to microscope designs. Laser beam expanders beam expanders optical assemblies. The instrument is used in a fashion similar to using a telescope and produces straight line telescopic rays or prismatic rays, such as the rays one can see as light is reflected off the facets of a crystal. When used as intracavity beam expanders, in laser resonators, these telescopes provide twodimensional beam expansion in the 2050 range.
It is designed for use with co2 lasers having up to 12mm beam diameter and w cw power. Variable attenuators for linearly polarized laser beam. A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. Bez10 zoom beam expander introduction the bez10 zoom beamexpander has both zoom and focus controls. Our adjustable focus beam expander makes it possible to reduce the diameter of your laser s beam at maximum range increasing the effective range of your laser by up to 10 times.
The focal lengthpoint of the lens is placed so that the most divergent direction is focused to almost perfectly parallel but the other dimension will continue to have some small divergence because the divergence. This equation is based on the paraxial approximation, and is thus valid only for beams with moderately strong divergence a higher beam divergence for a given beam radius, i. Designing your own beam expander provides the flexibility to design to your exact application specifications, and using stock optics reduces your time from design to prototype to days. Beam divergence measures how much the laser beam expands per meter. Beam splitters if used should be attached before the expander between the laser and the expander since they absorb very little and therefore can withstand much higher power densities than either the filters or the expander. Classes 1 and 2 include many everyday devices such as laser pointers, laser printers, grocery scanners, and cd players. Telescopic beam expanders include refracting and reflective telescopes. Edmund optics barrington, nj has expanded its techspec variable beam expander line to include 355nm wavelength versions with a 28x magnification range, with particular utility in ultraviolet uv laser machining. Beam expanders are used in applications such as laser scanning, interferometry, and remote sensing. Beatrix will consist of an xray source in the focus a grazing incidence paraboloidal mirror to obtain a parallel beam, followed by a. Beam expander selection guide in many laser based applications, beam expanders are an essential component of the optical system. Even if youre using the telescope as a beam expander, it will still not work perfectly unless the laser is collimated. Divergence is the increase in laser beam diameter with distance from the aperture from which the beam emerges in any plane that intersect the beam axis.
As for point 2, focusing of a laser beam without a lens can happen due to some nonlinear effects if you are at veryhigh intensities in some type of medium air or otherwise, but that is a different subject all together. If it is necessary to use exact optical laser system, recommended to use the beam expander with diopter correction function. Co2 laser beam expander can improve beam collimation characteristics. A light or laser beam expander is a scientific instrument that allows parallel light or laser rays to have an input beam expanded to become a larger output beam. And if the parallel light beam incident into the beam expander, the light would be emitted in expanded beam. It is important to remember that m is positive for the cassegrain expander and negative for the gregorian. Buy 4axis laser beam expander mountholder for laser markingengravingcuttingweld. In size restricted applications, it is desirable to use a compact beam expander but in most. Equation of laser beam divergence physics stack exchange. I have read some sources on the internet but it ended up in collimate the laser. Aspherical anamorphic lens for shaping laser diode beam. The input of each beam expander has internal sm05 0.
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