FBSR - Gaussian to Top Hat Beam Shaper

For many applications in laser material processing it is necessary to focus a Gaussian laser beam to the smallest possible spot size. In addition focused profiles often should be homogeneous. Therefore, TOPAG developed the so called FBSR beam shapers which create round Top Hat profiles with diffraction limited spot sizes. FBS stands for Focus-Beam-Shapers or Fundamental-Beam-mode-Shaping.

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The FBSR beam shaper can be combined with any objective or F-Theta lens. FBSR can be included at nearly any position into the beam path (even in front of or within a beam expander/telescope). The diameter of Top Hat in the focal plane will be 1.5 times larger than the diffraction limited Gaussian focus and is approximately given by 2*λ*f/d or λ/NA with the numerical aperture (NA) of the focused beam. FBSR elements need to be matched to the laser wavelength (λ) and the (input) beam diameter (d).






Model FBSR
Efficiency > 95% of input energy within Top Hat profile
Transmission > 99%, incl. AR/AR coating
Material UV Fused Silica
Dimensions dia. 25.4mm/thickness 3mm
Damage threshold 4J/cm² @ 532nm and 10ns
Select beam diameter d (@1/e2) 1.0, 1.5 … 10.0mm
Tolerance for input beam diameter < ±10%
Select wavelength/AR coating (standard) 1064/1030nm, 532/515nm, 355/343nm

Other sizes and wavelengths on request.

Model No: FBSR - beam diameter - wavelength


- Input beam should be single mode Gaussian beam (TEM00) with M² < 1.4.
- Free/clear aperture should be min. 2.2times larger than beam diameter (@1/e²) along total beam path

Recommended equipment: x-y-positioner for alignment of the beam shaper in x- and y-direction. Topag offers two different adjustment mounts, HSF01 and HSF02 (+ assembling of beam shaper and mount).



Do you have questions about FBSR?

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Do you have questions about our products?

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Give us a call | +49 6151 425978

TOPAG Lasertechnik GmbH
Nieder-Ramstädter Str. 247
64285 Darmstadt, Germany
Phone: +49 6151 4259 78
Fax: +49 6151 4259 88
E-mail: info@topag.de