Dynamic laser beam shaping for material processing using hybrid holograms

• Published in: Optics and laser technology 2018-06, Vol.102, p.68-73
• Main Authors: Liu, Dun, Wang, Yutao, Zhai, Zhongsheng, Fang, Zheng, Tao, Qing, Perrie, Walter, Edwarson, Stuart P., Dearden, Geoff
• Format: Article
• Language: English
• Subjects: Beam shaping; Binary grating; Diffraction; Geometric mask; Gratings (spectra); Holograms; Holography; Image reconstruction; Laser beams; Lasers; Spatial light modulator; Spatial light modulators; Stainless steel
• ISSN: 0030-3992; 1879-2545
• DOI: 10.1016/j.optlastec.2017.12.022

[Display omitted] •High quality arbitrary beam profile with low edge diffraction effect can be obtained.•The shaped beam can be reconstructed in the range of 0.5 mm at the image plane.•The beam local energy ratio observed by the CCD camera is up to 77.67%.•Dynamic beam shaping with a refresh rate of 25 Hz has been achieved. A high quality, dynamic laser beam shaping method is demonstrated by displaying a series of hybrid holograms onto a spatial light modulator (SLM), while each one of the holograms consists of a binary grating and a geometric mask. A diffraction effect around the shaped beam has been significantly reduced. Beam profiles of arbitrary shape, such as square, ring, triangle, pentagon and hexagon, can be conveniently obtained by loading the corresponding holograms on the SLM. The shaped beam can be reconstructed in the range of 0.5 mm at the image plane. Ablation on a polished stainless steel sample at the image plane are consistent with the beam shape at the diffraction near-field. The ±1st order and higher order beams can be completely removed when the grating period is smaller than 160 μm. The local energy ratio of the shaped beam observed by the CCD camera is up to 77.67%. Dynamic processing at 25 Hz using different shapes has also been achieved.