beamshaping for high -power lasers using freeform

Beamshaping for high-power lasers using freeform refractive optics

Roy McBride1, Natalia Trela, Matthew O. Currie, Duncan Walker*, Howard J. Baker

PowerPhotonic Ltd, 1 St David's Drive, St David's Business Park, Dalgety Bay, Fife KY11 9PF, UK

* Walker Optics, Edinburgh, UK

ABSTRACT

High power laser beamshapers based on lens arrays are widely used to generate square, rectangular or hexagonal flat-top

far-field beam profiles. These devices can provide high efficiency and excellent brightness preservation, but offer a limited

range of far-field profiles and can suffer from diffraction-related artefacts when used with spatially-coherent beams.

Diffractive optical elements (DOE) offer a far wider range of far-field profiles, and better speckle behavior, but bring

performance trade-offs in terms of brightness, efficiency, scattered power and residual zeroth-order power.

Freeform refractive optics offer additional choices in the design of high power laser beamshapers. Freeform lens arrays

offer a wider range of beam profile options than that available from catalogue lens array parts. Freeform field mapping

beamshapers can generate a wide range of application-specific beam profiles with high efficiency and, where required,

minimal reduction in brightness. More complex quasi-random freeform surfaces can act as a pseudorandom refractive

intensity mapping element (PRIME), providing a level of beamshaper design flexibility closer to that of DOEs, but without

the related high-order scatter and zeroth order leakage.

We describe the design and implementation of these different types of refractive beam shaper in fused silica, using

PowerPhotonic’s direct-write freeform fabrication process. This is ideal for use in high-power laser systems, where high

damage threshold and low loss are essential. We compare and contrast the performance, benefits and limitations of these

types of beamshaper, and describe how to select the ideal beamshaper type based on source coherence properties and

application beam profile requirements.

Keywords: Beam delivery, Beam shaping, High Power Laser, Optical fabrication, Micro-optics, Collimation,

1. INTRODUCTION

1.1 Beamshaping overview

High-power laser beamshaping involves converting an input beam, whose properties are generally determined by the laser

source, into a well-defined output beam, whose properties are determined by the process that the laser is being applied to.

Beamshaper design principles are well-established [1] and commercial beamshapers based on mature optical fabrication

processes are readily available [2].

Although a large range of standard beamshaping products already exists, the requirement space is even larger.

Consequently, designing a laser system based on catalogue beamshaper elements typically involves either compromising

system performance or increasing system complexity compared to what could be achieved using an optimal design.

Typical requirements driving beamshaper selection and design are:

Flexible choice of output beam profile

Insensitive to input beam

Large depth of focus

Brightness preservation

Speckle-free

Handle high peak power

High efficiency

Single, thin optical element

On-axis operation

Ease of integration into standard process head

1 [email protected] phone +44 1383 825910 fax +44 1383 825739 www.powerphotonic.com

High-Power Laser Materials Processing: Lasers, Beam Delivery, Diagnostics, and Applications III, edited by Friedhelm Dorsch, Proc. of SPIE Vol. 8963, 89630C · © 2014 SPIE

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1.2 Standard beamshaper configuration and use

Figure 1 Generic beamshaper configuration Figure 2 Use of beamshaper in fiber-coupled process head..

The generic beamshaper configuration is shown in Figure 1. A collimated input beam passes through the beamshaper,

which modifies the far-field properties of the beam. A focusing lens is then used to image this far-field onto the process

plane. The beamshaper will usually increase the divergence of the beam. The tolerable amount of divergence increase is

a key parameter driving system design. Figure 2 shows a common requirement for beamshaper deployment: reshaping the

process-plane beam profile in a fiber-coupled process head.

The near-field distribution immediately after the beamshaper is not usually critical from an optical performance viewpoint,

though any local focusing effects must be known and controlled in order to avoid damage to nearby optics, or indeed to

avoid air breakdown when high peak power is used.

1.3 Beamshaper types

Figure 3 Beamshaper family tree

Beamshapers can be broadly categorized into two types, shown in Figure 3 Beamshaper family tree:

Field mappers, which map adjacent patches from a known input field distribution into adjacent patches in a

defined output beam profile (Figure 4(a))

Beam integrators, often known as homogenizers, which slice the input beam into a number of patches which are

then superimposed to generate the output beam profile (Figure 4(b))

Field mappers provide smooth, speckle-free output beam profiles, and can be used to generate a phase-flat (minimum

divergence) output profile when depth of focus at the process plane is critical. They are, however, highly sensitive to input

beam dimensions and profile. The beam shaper must therefore be carefully matched to the input beam, and any changes

in input beam position, beam diameter, or beam profile, will strongly affect the output beam. Field mappers typically work

best with beams of low M2.

Beamshaper Focusing lens

Collimated input beam

Process plane

Without beamshaper

With beamshaper



Beam integrators, in contrast, are highly insensitive to changes in the input beam intensity profile, due to their

homogenizing properties. They are, however, prone to interferometric effects due to mixing these different regions of the

beam. This gives rise to strong diffraction and speckle effects when beam integrators are used with spatially-coherent

beams. Beam integrators therefore provide best performance for beams with medium to high M2.

(a) Field mapper (b) Beam integrator

Figure 4 Mapping of input beam onto output beam for the two basic beamshaper types. Input is taken to

be quasi-Gaussian (upper) and output taken to be flat-top (lower).

One consequence of this is that the most challenging regime for beamshaper design is where the input beam has low M2

but has variable properties, e.g. time-dependent variations in mode population or changes in beam profile due to operating

conditions contamination. Beam integration can compensate for these variations, but the resultant profile will inevitably

suffer from interferometric effects i.e. diffraction and speckle. These effects can be sometimes be mitigated by temporal

averaging over different mode profiles (produced e.g. by vibrating a beam delivery fiber) or by spatial averaging via the

thermal properties of the workpiece, but for individual short pulses with good spatial coherence, the effects of diffraction

or speckle are inescapable when using beam integrators.

2. FREEFORM DIRECT-WRITE OPTICAL FABRICATION

PowerPhotonic’s optical products are fabricated using a unique, laser-based freeform direct-write process. A laser material

removal process first generates a programmed net shape in the fused silica substrate material. Then a second laser-based

process locally reflows the material to remove cutting marks, resulting in an ultrasmooth, low-scatter, refractive surface.

Since no part-specific tooling or masks are required, realizing a new design of component does not incur the level of NRE

required for mask-based processing. The manufacturing process is short, so prototype parts can be generated rapidly,

cutting both lead time for custom micro-optics when compared to other free-form grayscale fabrication processes [3][4][5].

The same wafer-scale manufacturing process used make one-off prototypes is used to manufacture volume parts, so once

proven, a new design can be directly scaled up to volume manufacture.

The process is entirely freeform, with no symmetry restrictions, and is easily capable of making the complex surfaces

required by many beamshapers. Fabrication in fused silica, plus laser surface smoothing, results in parts with excellent

power handling and damage resistance properties, which are ideally suited to high-power laser applications.

3. FIELD MAPPING BEAMSHAPERS

3.1 Use of field mappers

Field mappers, commonly known as “flat-toppers”, are mainly used to transform a collimated Gaussian beam into a circular

flat-top beam. The range of beams achievable is far more general than this, however. Using a single field mapper, beams

of arbitrary radial intensity distribution 𝐼(𝑟) can be generated from a circular Gaussian beam. Further, since the radial

Gaussian function is separable in 𝑥 and 𝑦, any separable intensity distribution of the form 𝐼(𝑥, 𝑦) = 𝐼(𝑥)𝐼(𝑦) can be

generated using a field mapper.

Typically, the goal is only to generate a flat intensity profile, and the wavefront at the process plane need not be flat. A

second, phase-flattening element can be used to flatten the wavefront and hence minimize divergence of the shaped beam.



This can be relayed to a workpiece using a 4f system in order to maximize the depth of focus of the beam at the workpiece

and keep beamshaping optics clear of spatter etc. ejected from the workpiece.

The requirement to match the field mapper to the input beam diameter is one of the factors that most strongly limits the

use of field mappers. A mismatch in beam diameter of a few percent has a significant impact on profile flatness. In order

to use a catalogue field-mapping optic, therefore, adjustable beam-expanding optics are typically required to bring the

actual source beam to the design diameter of the catalogue field-mapper. This additional complexity makes deployment

of standard field-mappers in process heads challenging, as process heads typically only have room for a simple, thin,

additional optic between the collimating and focusing lens.

Fabrication of field mappers by PowerPhotonic’s freeform direct-write process allows application-specific field mappers

to be produced economically in both low and high volumes. These application-specific optics are matched to the input

beam properties and the required output beam profile. Fine tuning of beam diameter, to optimize the match between input

beam and field mapper, can typically be achieved with fine adjustments to the existing optical system, enabling the

beamshaper to be integrated into the optical system with minimal additional effort.

3.2 Field mapper design

Field mapper design for transforming a Gaussian input beam into radial and 𝑥𝑦-separable output intensity profiles is

straightforward and well-documented [1]. For the simplest cases of circular and rectangular flat-top output, explicit

expressions for the surface profile exist. Figure 5 shows a design example. Although polynomial approximations to the

ideal surface profile have been published [6], best performance is achieved using a fully freeform description of the surface.

Design is easiest carried out in a numerical package such as matlab™. We find it good practice to also verify our design

in a standard optical design package, such as Zemax, by loading in the freeform surface as a grid sag object.

(a) Source: Gaussian intensity profile,

𝑑0 = 10mm (1/𝑒2)

(b) Radial cross-section of surface profile

(c) Zemax simulation of output:

Source M2=1

(d) Zemax simulation of output:

Source M2>>1

Figure 5 Field mapper design example: transformation of a 10mm diameter Gaussian beam

into a 10mrad flat-top far-field

-10 -5 0 5 100

20

40

60

80

100

r / mm

Sag /

m

0.0000

0.4977

0.9954

1.4930

1.9907

2.4884

2.9861

3.4838

3.9814

4.4791

4.9768

Detector Image: Incoherent Irradiance

25/11/2013Detector 6, NSCG Surface 1: CoherentSize 10.000 W X 10.000 H Millimeters, Pixels 100 W X 100 H, Total Hits = 1000000Peak Irradiance : 4.9768E+000 Watts/cm̂ 2Total Power : 9.9003E-001 Watts

0.0000

0.4667

0.9334

1.4001

1.8668

2.3336

2.8003

3.2670

3.7337

4.2004

4.6671

Detector Image: Incoherent Irradiance

25/11/2013Detector 5, NSCG Surface 1: FFSize 10.000 W X 10.000 H Millimeters, Pixels 50 W X 50 H, Total Hits = 1000000Peak Irradiance : 4.6671E+000 Watts/cm̂ 2Total Power : 9.9003E-001 Watts



Figure 6 shows field-mapper test results for different kinds of flat-top generating element. The surface profiles of Figure

6 (c) and (d) show how the focusing lens can be integrated into the flat-top element itself, leading to a particularly simple

and practical optical system. The ability to incorporate multiple optical functions into a single, monolithic, optical element

is a key feature of PowerPhotonic’s freeform fabrication process.

(a) Gaussian source beam, 1.064µm

(b) Output beam profiles for different field mapping beam shaper designs:

circular, donut, square and rectangular flat-top

(c) Surface profile for generation of circular

flat-top, incorporating focusing lens

(d) Surface profile for generation of square

flat-top, incorporating focusing lens

Figure 6 Field mapper test results

4. BEAM INTEGRATORS

4.1 Imaging beam integrator

The imaging beam integrator, or fly’s eye homogenizer [7], divides the input beam into a regular array of

patches, and generates a set of superimposed images of each patch in the far-field. These are then imaged

onto the process plane by a focusing lens, as shown in Figure 7 (a).

This beamshaper comprises two lens arrays used in tandem, with the second array at focal length distance

from the first. The purpose of the first array is to direct all light incident on a single cell in the first array

onto the corresponding lens in the second array. The second lens images the beam profile over the cell at

infinity. This type of beamshaper is used to generate line, square, rectangular or hexagonal beam profiles.

Figure 7 (d) shows measured beam profile data for a system designed to generate a hexagonal output beam

profile.

The imaging beam integrator is typically the best choice for beams with high M2, since the output

divergence is determined by the design, not by the input beam properties. All of the input power within



the input acceptance NA is transferred into the desired output profile, making this type of beamshaper

highly insensitive to changes in input beam divergence.

This type of beamshaper is not suited for use with high power, low M2 beams, however. The concentration

of power produced by the first lens creates a hotspot on the second lens, which can lead to laser damage.

Additionally, the periodic structure of the lens array results in 𝑥𝑦-seperable diffraction artefacts which can

easily print-through onto the process.

PowerPhotonic’s freeform direct-write fabrication process brings several specific benefits to this type of

beamshaper. By allowing free choice of lens pitch, lens focal length, and array geometry, a much greater

design space is accessible than is possible using standard parts. Also, the smooth nature of the valleys

between lenses produced by PowerPhotonic’s fabrication process means that laser power incident on the

region commonly known as the “dead zone” is largely directed into the desired output profile, avoiding

the scatter losses produced by sharper transitions.

(a) Optical arrangement (b) Solid model

(c) Surface profile: hex array (d) Test results: hex array

Figure 7 Imaging beam integrator

4.2 Convolving beam integrators

This class of designs is also known as the Diffracting Beam Integrator. We use the term “convolving” instead, for two

reasons: to avoid confusion with the specific case of the Diffractive Optical Element (DOE) and because, in many cases,

behavior is adequately described by ray optics

Convolving beam integrators have much in common with imaging beam integrators: the input beam is divided into cells,

a far-field pattern is generated for each cell, and these are superimposed in the far-field then imaged onto the process plane

by a focusing lens.

The key difference between the two types is that while the imaging beam integrator is largely insensitive to input beam

divergence, in the case of the convolving beam integrator the input divergence is essentially convolved with the point

spread function (PSF) for a single cell of the optic to generate the output intensity profile for that cell.

Consequently, convolving beam integrators should only be used when the desired output divergence is significantly larger

than the input divergence.

Due to the mixing of beams from different cells, all types of beam integrator, both convolving and imaging, suffer from

diffraction and speckle effects when used with spatially-coherent (low M2) beams.



4.3 Single lens array homogenizer

A single array of identical lenses can be used as a convolving beam integrator, using the plane-wave-incident far-field PSF

of a single lens as the convolving term.

As for the imaging homogenizer, cylindrical and spherical lens arrays can be used to generate line, square, rectangular, or

hexagonal beam profiles. The single lens array homogenizer allows far greater design freedom than this, however, as, for

example, an array of identical axicon-type lenses can be used to generate ring patterns while groups of non-identical tilted

lenses can be used to generate other application-specific beam profiles.

In this case, PowerPhotonic’s freeform direct-write process allows not only free choice of lens pitch, lens focal length, and

array geometry, but also enables the generation of more complex beam patterns using non-spherical lens profiles, and

differing types of lens combined into in a single array.

(a) Square lens array surface profile (b) Example of hexagonal lens array

(c) Beam profile: square array,

showing source print-through

(d) Beam profile: “frame” array of

tilted lenslets

Figure 8 Single lens array homogenizer (convolving beam integrator)

4.4 Diffractive Optical Element (DOE)

The Diffractive Optical Element (DOE) is a pixelated phase grating with discrete phase steps. Binary (two-level) DOEs

are most common, though multilevel DOEs are also available.

DOEs are generally designed by Iterative Fourier Transform (IFT) techniques [8] and provide an extremely broad range

of flexibility in beamshaper design, unmatched by any other type of beamshaper. Although they inevitably suffer from

speckle when used with spatially-coherent sources, the speckle is randomized, so there is less process print-through,

particularly where thermal effects in the process can spatially average the effects of speckle.

DOEs are typically made using single or multistep photolithography combined with reactive ion etching (RIE). Multilevel

DOEs, produced by multistep processing, provide higher efficiency and fewer artefacts, but precise step transitions are

difficult to maintain over increased numbers of levels, often exacerbating problems of scatter and laser damage.



(a) Off-axis arrangement to remove DOE zeroth order artefacts (b) Surface profile of 4-level DOE

Figure 9 DOE use in laser beamshaping

While they provide the benefit of an extremely broad design space, DOEs have some drawbacks that limit their use in high

power laser beamshaping applications:

Limited efficiency: the maximum theoretical efficiency for a binary DOE is around 80%, and fabricated optics

often exhibit substantially lower efficiency than this. Multilevel DOEs have higher efficiency, but fabrication

requirements are more challenging, and multilevel fabrication introduces other non-ideal behavior.

Scatter: the limited efficiency is a result of high levels of diffracted and scattered power. In addition to reducing

process efficiency, managing this lost power can require significant engineering effort in a high power system.

Zeroth order leakage: even with an ideal design, residual on-axis power due to imperfect fabrication would

produce a hotspot in the center of the beam for an axial beamshaper configuration, so off-axis operation (see

Figure 9 (a)) is required to avoid this. Off-axis operation prevents easy integration into standard process head

architectures, and the zeroth-order power must additionally be dissipated and removed.

Laser damage: The sharp transitions in a DOE are susceptible to laser damage at high peak power. Imperfect

transitions in multilevel DOEs can further increase damage susceptibility.

Strong wavelength dependence: the diffractive nature of these optics makes them strongly wavelength

dependent, so DOE design must be closely matched to the source wavelength.

4.5 Pseudorandom Refractive Intensity Mapping Element (PRIME)

PowerPhotonic’s freeform fabrication process is designed specifically to product smooth, refractive optics, so it avoids the

discretized phase steps and pixellation used in the DOE, which are a result of the process limitations of photolithography

using binary masks. PowerPhotonic’s process can therefore be used to realize optics designed along similar principles,

but without introducing either of these discretization steps.

The process for designing such an optical element has been described by Dixit [9]. It is essentially an IFT technique,

similar to that used to design DOEs, but without discretization of phase, and forbidding phase discontinuity and hence

phase branching. In DOEs, these allow greater design flexibility, but contribute to scatter loss. Changing from a DOE to

a PRIME approach therefore trades design flexibility for power handling capability.

PRIME design begins with a pseudorandom surface, which is iterated until it produces the required far-field profile.

Although the design process we use is based on a diffraction calculation, the resultant optic is essentially a refractive

device, mapping intensity from small cells in the input beam over the whole of the output beam. For this reason, we have

given this type of element the name PRIME = Pseudorandom Refractive Intensity Mapping Element. We use this term to

describe a continuous phase screen that is specifically designed for beamshaping.



PRIME optics directly overcome the main deficiencies of DOEs for high-power applications. The most relevant properties

of PRIME beamshapers in this regard are:

High efficiency: no diffraction losses

Very low scatter: due to the ultrasmooth refractive surface

No zeroth order leakage: so these beamshapers can be used on axis, and integrated into standard process head

architectures

High laser damage threshold: PowerPhotonic’s fabrication process results in ultrasmooth surfaces that are

particularly resistant to laser damage, and the smooth, slowly-varying surface avoids generation of local hotspots

in the beam

Wavelength independence: these are essentially refractive optics, and the gross behavior is essentially

wavelength-independent. The exact structure of speckle will, of course, be wavelength dependent when used

with sources of high spatial coherence.

Additionally, the highly complex, smooth surface profile required for these optics is ideally suited to PowerPhotonic’s

direct-write freeform fabrication process.

Figure 10 shows a typical PRIME optic. The surface profile remains very similar to the initial pseudorandom seed surface,

which generates a Gaussian beam profile. The ITF algorithm gently nudges surface slopes until output beam profile closely

matches the target distribution. The resultant surface looks very much like security glass.

(a) Design surface profile of PRIME optic (b) Surface detail of fabricated optic

Figure 10 A typical PRIME optic

Design by IFT algorithm

Zemax simulation: singlemode

Zemax simulation: multimode

We implemented the design algorithm of Dixit [9] and used it to design two beamshapers, one generating a 10mrad full

angle square flat top, the other generating a 10mrad diameter circular flat top, as shown in the first column of Figure 11.

In order to verify our design process, we loaded our design into Zemax as a grid sag object, and modelled the behavior for

sources of high and low spatial coherence, as shown in the second and third columns of Figure 11.

We then fabricated these parts using PowerPhotonic’s’ direct-write freeform fabrication process. These parts were

manufactured using PowerPhotonic’s LightForge™ process, which is specifically designed for rapid prototyping.



10mrad square flat-top

10mrad circular flat-top

Figure 11 Design and Zemax simulation of PRIME beamshaper optics

In order to verify correct behavior of our fabrication process, we measured the surface profile of the parts, loaded that data

into Zemax, and re-ran the simulation for the profiled surface. The results are shown in Figure 12. This confirmed that the

as-fabricated parts followed the design closely enough to generate the required flat-top profiles.

Finally, we tested the parts using the setup shown in Figure 13. The source was a fiber-coupled red diode laser, wavelength

635nm, delivered via a 1m fiber of core diameter 62.5µm and NA 0.275, resulting in a beam diameter of approximately

11mm after the collimating lens. The collimated beam passed through the beamshaper, and was then focused onto a

Spiricon beam profiler camera using a 100mm EFL lens, so that the output beam was fully contained within the camera

sensor area.

The modal properties of this source are particularly ugly, as shown in Figure 14. The output beam exhibited strong speckle,

which was very sensitive to movement of the delivery fiber. This is a typical result of launching a spatially coherent source

into an overmoded fiber.

The output beam generated by the beamshaper is shown in Figure 15. The first column shows the output beam with a

static delivery fiber. The design beam profiles are produced as intended, with a fine speckle structure superimposed, due

to the high spatial coherence of the source. A source of lower coherence (uniform mutually incoherent filling of fiber

modes) was simulated by vibrating the fiber. The result is shown in the second column of Figure 15. This shows a much

smoother output intensity profile.



Design by IFT algorithm

Zemax simulation: singlemode



Figure 12 Profilometer data for as-fabricated PRIME optic, and Zemax simulation for profile data

Figure 13 Test setup for PRIME optic



Figure 14 Beam profile of PRIME fiber-coupled test source

Test results, static delivery fiber

Test results, vibrating delivery fiber



Figure 15 Test results for PRIME optic using fiber-coupled red diode laser source



(a) Spatially coherent source (low M2) (b) Spatially-incoherent source (high M2)

Figure 16 Simulation data for PRIME optics demonstrating design for a highly asymmetric output beam

In order to demonstrate the flexibility of the PRIME beamshaper concept, we also designed and simulated a highly

asymmetric output profile. The profile chosen was a pair of square beams of different size, spaced vertically apart. The

results of designing the required surface and simulating the output beam for sources of high and low spatial coherence is

shown in Figure 16. This demonstrates that the design process is genuinely highly flexible, and that the square and circular

beam geometries designed earlier were truly a result of design, and were not artefacts of the system geometry.

5. CONCLUSIONS

High power applications place stringent demands on laser beamshaping optics, which must provide high efficiency while

handling high peak (GW/cm2) and average (kW/cm2) power densities. Integration into standard process heads strongly

favors compact beamshaper designs, ideally single, thin, elements with smooth, low-scatter surfaces. These requirements

particularly favor the use of refractive designs fabricated in fused silica.

While there are only two fundamental types of refractive beamshaper, field mappers and beam integrators, the latter

category covers a wide range of designs and capabilities. Selection of beamshaper type is driven primarily by source

spatial coherence properties, with selection of subtype and detailed design then being driven by the precise application

requirements for output beam profile.

For spatially-coherent beams, such as low-M2 fiber lasers and DPSS, field mappers offer the best possible performance,

in terms of efficiency and output beam uniformity. Achieving this performance requires stable, well-characterized beam

properties, and a beamshaper geometry that is closely matched to the source beam width.

For beams with lower spatial coherence, a choice can be made between the different types of beam integrator.

Conventional beam integrator designs, based on microlens arrays, can provide both standard beam profiles (square,

rectangular, hexagonal) and application-specific profiles (e.g. annular) within a restricted range of beam symmetries.

In contrast, PRIME beamshapers offer a near-arbitrary choice of beam profile, while retaining the key advantage of beam

integrators: homogenization for insensitivity to input profile. These can be used to generate conventional square and

circular beams from sources of arbitrary near- and far-field profile. PRIME beamshapers can also be used to generate

highly asymmetric beams – this design approach imposes no symmetry restrictions.

Field mappers, lens-array convolving integrators and PRIME beamshapers can all be realized as a single, thin optical

element, for ease of integration into industrial laser process heads, enabling a dramatic increase in system functionality

with minimum additional engineering effort. In all three of these design types, PowerPhotonic’s freeform direct-write



process is an ideal fabrication technology, delivering low loss fused silica optics with low scatter and high damage

threshold. A key feature of this process is the ability to make application-specific beamshapers, providing the greatest

possible design freedom, and in particular enabling prototype designs to be fabricated and evaluated without incurring

NRE costs for masks or other hard tooling. This wafer-based process provides an economic route to beamshaper

realization, from first trial parts all the way through to volume manufacture. It allows optical designers and manufacturers

of material processing system to produce application-specific beam profiles without having to make the compromises

otherwise imposed by designing with catalogue beamshaper components.

Combining high efficiency, high damage resistance, compact construction, and enabling rapid realization and evaluation

of application-specific beam profiles, PowerPhotonic’s unique fabrication capability is enabling freeform refractive optics

to become a practical, flexible and economic platform for beamshaping in high-power laser systems.

ACKNOWLEDGEMENTS

The authors thank Dilas Inc. for their kind permission to reproduce the hexagonal beam profile in Figure 7 (d).

REFERENCES

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[6] Powell, I., “Linear deiverging lens”, US patent no. 4826299 (1989)

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beamshaping for high -power lasers using freeform

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