Using laser beam splitting in laser material processing applications

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Beam splitting of laser beams is the effect of the processing output of a beam splitter DOE,an optical component that produces an array of beams commonly used in a variety of applications including industrial,medical and sensing.This article describes some innovative applications of split beam laser beams in industrial material processing applications.

What is a multi-point beam splitter?How to produce a split laser beam

Splitting of a laser beam is the result of using a DOE diffraction beam splitter with an incident laser beam.This creates an array of split beams,each sharing the same intensity distribution and other characteristics of the input beam(e.g.wavelength,polarisation),but with different propagation angles.The array has an angular spacing determined by the grating equation,which gives an almost identical spacing for small splitting angles.When focused through a suitable lens,this beam array produces a matrix or line of dots with predefined spacing and arrangement,the size of which is determined by the angular divergence of the laser beam.Such dot arrays can be used to increase the throughput of many industrial laser processes.

Using split beam laser beams in laser beam processing applications

Beam arrays can be used for many industrial applications,particularly laser beam processing and surface texturing.

Individual laser beams,while easily controlled using settings such as oscillator scanners and F-theta lenses,impose inherent limitations on the processing throughput of laser-based machines.As laser power increases and process costs per joule or watt fall,these limitations become increasingly apparent.In order to utilise the increasing laser power,diffraction beam splitters must be used as no scanning system,not even polygon scanners,can scan fast enough to fully disperse the laser power over a large area.

For the purposes of surface functionalisation,this application limitation of scanning systems becomes particularly important in the processing of laser beams on periodically structured surfaces.To achieve realistic processing speeds for industrial use,structuring rates of 1m 2/min or more must be achieved,which means that millions of spot-sized indentations must be produced within a timescale of a few minutes.No scanner system can scan a single spot so quickly and accurately,and Holo/Or's DLITe beam splitter DOE produces a two-dimensional laser beam,with each pulse forming an array of thousands of indentations.The 2D dot array is then scanned over the surface to be functionalised,resulting in high throughput texturisation at industrial rates.This scanning of the split laser beam can be obtained using a platform shift or rolling bar,or by using a vibrating mirror or polygon scanner.As diffractive optics offers full flexibility in terms of spot matrix shape,the area of the laser beam can be customised to better suit the scanning method and laser parameters.