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Student Homogeneous intensity within the Rayleigh length and enhanced depth of focus for Gaussian beams

Wednesday (24.06.2020)
12:14 - 12:17 Room 1
Part of:
- Poster Processing of Functional Texturing on Micro-fibers by Laser Induced Periodic Surface Structures 1 Prof. Masaki Yamaguchi
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- Poster *student* Femto- and nanosecond laser surface modification of stainless steel 1 Dipl.-Volkswirt Paulina Dzienny
- Poster Laser writing of waveguides in porous glass for small molecules detection 1 Dr. Roman Zakoldaev
- Poster *student* Homogeneous intensity within the Rayleigh length and enhanced depth of focus for Gaussian beams 1 Christian Bischoff
Session Chair

Session PS: Poster Session 01
Belongs to:
Topic PS: Poster Session

Pulsed solid-state lasers are well established for many micro machining processes and typically provide high quality Gaussian laser beams which are focused onto the material for the processing. The width of the focused Gaussian beam changes continuously during the propagation, but the principle intensity distribution is retained. At the focal plane, the width shows the smallest size, which is called the waist and is only limited by the diffraction limit of the light. The waist results from the divergence in front of and behind the focal plane and determines the Rayleigh length. The Rayleigh length is the distance from the waist at which the width of the Gaussian beam increases by a factor of 1.41 or the intensity decreases by a factor of 2. With regard to laser material processing, these changes in spot size and intensity are typically undesirable. For example, variations in surface profiles or thickness of the processed material could require adjustment of focus.

We present a new beam shaping method for Gaussian laser beams based on a development of the Fundamental Beam Mode Shaper (FBS) concept. By applying the new phase information to the Gaussian beam, the caustic of a focused Gaussian beam is changed. Within the Rayleigh length the focused beam shows now almost constant intensity. In addition, the depth of focused increases by 30% in comparison to the Rayleigh length of the Gaussian beam.

The homogeneous intensity within the Rayleigh length and the higher depth of focus realized by this new beam shaping has the potential to enhance the stability of laser machining processes, to improve the process window and to simplify the process control.

Christian Bischoff
Topag Lasertechnik GmbH
Additional Authors:
  • Dr. Erwin Jäger
    Topag Lasertechnik GmbH
  • Dr. Udo Umhofer
    Topag Lasertechnik GmbH
  • Dr. Andrés Fabián Lasagni
    Technische Universität Dresden


Category Short file description File description File Size
Poster Version1 for printed booklet and and web site 622 KB Download
Poster presentation A0 final poster 2 MB Download