Beam Shaping

Discover easy Gauss to Top-Hat transformation.

Aspheric laser beam shaper

With the a|TopShape, a|AiryShape, and a|SqAiryShape from the laser beam shaping range, asphericon offers efficient top hat beam shapers for maximum results in all laser applications. Based on aspherical optics, these modular components allow the straightforward transformation of Gaussian laser beams into various round and square top hat profiles. Thanks to highly precise manufacturing technology, these laser beam shapers are distinguished by unparalleled beam quality and can be used in diverse applications.


The a|TopShape is an innovative beam shaper that transforms collimated Gaussian beams into slightly enlarged (M ≈ 1.5) collimated top hat beams with uniform intensity distribution. It’s distinguished by its compact design and outstanding optical quality (beam uniformity < 0.1). The laser beam shaper covers a wide spectral range (320–1,600 nm), accepts different input beam diameters up to ±10%, and generates a stable beam profile for at least 300 mm.

Using the LongDistance version (a|TopShape LD), even homogeneous beam profiles can be achieved at a working distance of up to 1.5 m. With the new a|TopShape LDX, the beam profile can be shifted to large working distances of up to 3 m by adjusting the input beam diameter. Since the effective working distance decreases as the beam size is reduced, a|TopShape LD and LDX are particularly suitable for applications requiring smaller beam diameters. For applications where the beam profile’s homogeneity is less crucial, longer working distances are also possible (see Flexibility).

a|TopShape LD
a|TopShape LDX


  • Outstanding optical quality (beam uniformity up to 0.05) without drop in performance
  • Wide spectral range (320–1,600 nm) and suitable for multi-wavelength applications
  • Propagation depth (with beam uniformity < 0.1):
    • a|TopShape: At least 300 mm
    • a|TopShape: LD up to 1.5 m
    • a|TopShape LDX: At least 1.5 m – can be shifted to longer working distances of at least 3 m
  • Input beam diameter:
    • @ 1/e2 = 10 mm (± 10%) for a|TopShape and a|TopShape LD
    • @ 1/e2 = 10,0 - 10,4 mm for a|TopShape LDX
  • Output beam diameter@ FWHM = between 15.2 mm and 15.7 mm
  • Laser induced damage threshold: 12 J/cm², 100 Hz, 6 ns, 532 nm, 532 nm
    For applications with higher laser power, we invite you to explore our V-coating options. Contact us for a personalized solution tailored to your needs.

Technical dimensions [mm]


The key feature of the TopShape LD and LDX is their long, stable propagation distance. The following figure shows the intensity distribution at working distances of 100 mm, 800 mm, 1500 mm, and 3200 mm. They’re both characterized by beam uniformity of 0.05 up to 1,500 mm. By varying the input beam diameter, beam uniformity of 0.06 up to as much as 3,200 mm can be guaranteed for the TopShape LDX.

Due to its flexible output diameter, the a|VariColl is the ideal collimator for shifting the working range of the a|TopShape LDX. For more information, see Fiber Collimation & Fiber Coupling..

Wavelength range

Covered wavelength range of the laser beamformer a|TopShape for design wavelengths of [nm] 355, 632, and 1064 and a|TopShape LD and LDX for design wavelengths of [nm] 355, 405, 532, 632, 780, and 1064.

Advantages of Top-Hat intensity distributions

Beam shaping has an important role to play, e.g. in applications in laser material processing or microscopy (e.g.Fluorescence Microscopy). Gaussian profiles are usually used in laser applications. They have weaknesses regarding the distribution of their intensity. With homogeneous intensity distributions, so-called Top-Hats, significantly better results can be achieved than with Gaussian profiles. They enable, for example, a high edge steepness of the laser beam and thus the quality of the cutting edge or an even illumination. Benefit from easy handling for your application! Convert Gaussian laser profiles into collimated or focused Top-Hat intensity distributions with asphericon’s beam shapers.

Beam shaping optics for generating collimated Top-Hats directly from stock.

a|AiryShape & a|SqAiryShape

Another beam shaper optimized for wavelengths from 300 nm up to 1600 nm is the a|AiryShape. This beam shaping element enables in combination with a focusing lens the transformation of collimated Gaussian beams into different focused beam profiles (e.g. Top-Hat, Donut). Thanks to its compact design, the a|AiryShape can be easily integrated into existing set-ups.

Want to create squared Top-Hat profiles in the focus? No problem with the a|SqAiryShape. This beam shaper generates in combination with a focusing lens different squared focused beam profiles (e.g. Top-Hat, Donut) from collimated Gaussian beams. Optimized for the wavelength range from 300 nm to 1600 nm, it also impresses with its compact design (only 17.3 mm in length) and can be easily incorporated into existing application set-ups. Its working distance can be extremely reduced depending on the focusing lens used. Integrating an a|SqAiryShape together with a lens of 200 mm focal length and an a|BeamExpander already reduces the total length by 25%.

Specifications & Technical dimensions [mm]

  • Generation of different beam profiles
  • Profile size easily scalable by focal length
  • Optimized for wavelengths from 300 nm to 1600 nm
  • Easy integration into existing set-ups
  • Perfect alignment by high-precision mounting
  • Compact design
  • Input beam diameter @ 1/e2 = 10 mm; output beam diameter dAiry = 10 mm
  • Laser induced damage threshold: 12 J/cm2, 100 Hz, 6 ns, 532 nm

Performance & Flexibility

In the figure below normalized beam profile sections along its propagation direction (z-axis) are summarized in one diagram. The detected range is ± 1.5 mm around the waist location. Furthermore, the corresponding most interesting intensity profiles in the different working planes are shown as 2D and cross-sectional plots. Both plots of the characteristic beam profiles are generated with the a|AiryShape (λ = 635 nm). According to the working principle of the a|AiryShape, it is possible, not just to generate one Top-Hat beam profile in the focal plane of a focusing lens but also to create various profiles in different working distances for your flexibility. The generation of the shown beam profiles depends on the input beam quality. For optimum results a perfect collimated beam with minimized wavefront aberrations is required.

The figure on the right shows beam profile cross sections of the a|SqAiryShape (λ = 1064 nm), as well as its intensity profiles in the different working planes. The detected range is ± 6 mm around the beam waist. Due to the working principle of the a|SqAiryShape, not only one squared Top-Hat profile is generated in the focal region, but a variety of profiles with four-fold symmetry. Using the a|SqAiryShape, the generation of the beam profiles also depends on the quality of the input beam. For optimum results, a perfect collimated beam with minimized wavefront aberrations is required.

Wavelength range

Based on the BeamTuning elements the AiryShape covers a wide wavelength range for your challenging application.

Beam shapers for round and squared focused Top-Hat profiles.

Reference projects

Surface functionalization (LIPSS) with Top-Hat profiles
Despite the loss of intensity towards the profile edge and related inhomogeneities, Gaussian intensity distributions are preferred for structuring surfaces. In collaboration with the Otto Schott Institute for Materials Research in Jena, asphericon analyzed the effect of Top-Hat distributions with respect to their suitability for the generation of laser-induced periodic surface structures (LIPSS) on stainless steel.
Beam shaper for laser material processing
Although Gaussian beam profiles can be used to generate small structure sizes by direct material ablation, they show weaknesses in terms of ablation depth and quality. Due to their characteristic shape of the profile, the intensity decreases at the edges of the beam and causes inhomogeneous ablations.
Beam shaper for fluorescence microscopy
The analysis of measurement images based on laser-based wide-field fluorescence microscopy quickly becomes invalid if it is based on unevenly illuminated Gaussian beam profiles. Using the a|TopShape was able to provide assistance here. A conversion of the Gaussian beams in a microscopy set-up of the CREOL research institute into homogeneous flat-top profiles ensures uniform illumination of the slide and thus more clearly legible images.
Beam shaping optics for laser welding
Additive manufacturing processes are increasingly being used for the production of complex components with a high degree of automation. Thanks to precise laser beam guidance, they enable a layered, flexible construction, e.g. of binomial structures. Hybrid processes combine conventionally manufactured structures with delicate structures created by additive manufacturing using laser welding.
Beam shapers for square top hats in the focal point
Laser-basierte Verfahren haben sich vor allem im Bereich der additiven Fertigung etabliert. Sie ermöglichen unter anderem die Anpassung der Intensitätsverteilung an den gewünschten Wechselwirkungsprozess zwischen Material und Laserstrahl. In einer Kooperationsarbeit mit dem Otto-Schott-Institut für Materialforschung (OSIM) in Jena konnte die Produktpalette der asphericon BeamTuning-Serie um ein neuartiges refraktives Strahlformungselement erweitert werden.

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