Using a digital micromirror device for high-precision laser-based manufacturing on the microscale Please use the dd month yyyy format for the date for example 11 January 2008. The main title can be one or two lines long. B. Mills, D. J. Heath, M. Feinaeugle, R. W. Eason Optoelectronics Research Centre, University of Southampton, UK

Outline The manufacturing process The experimental setup Results: Additive & subtractive manufacturing Advanced techniques Future work and conclusions

The Manufacturing Process + = 5 mm pulsed laser beam shaping precision manufacturing

The Manufacturing Process Using 800nm wavelength, 150 femtosecond laser pulses Spatial intensity profile of each laser pulse is modified by the DLP® 3000, and then imaged on to the sample array of mirrors, showing the pattern (the DLP® 3000) sample is continuously translated laser pulses  input focussing objective sample movement direction  spatially-shaped laser pulses 

Single mJ pulses, from a Ti:sapphire 800nm amplifier, 150fs pulses Experimental Setup Single mJ pulses, from a Ti:sapphire 800nm amplifier, 150fs pulses Energy density on sample is 1- 10J/cm2 Energy density on DLP® 3000 is ~1mJ/cm2 Well below damage threshold of DLP®3000 due to magnification

Technical Consideration Laser light is spatially coherent Multiple diffraction peaks from DMD Intensity samples a sinc2(ϴ) distribution 2 d sin(ϴ) = n λ 3D distribution

Technical Consideration Laser light is spatially coherent Multiple diffraction peaks from DMD Intensity samples a sinc2(ϴ) distribution Observed effect We image the central diffraction peak onto the sample ~1/3 efficiency (useful light out). 2 d sin(ϴ) = n λ 3D distribution Photo of array of diffraction peaks

Subtractive manufacturing Additive manufacturing Experimental Results Subtractive manufacturing Additive manufacturing 2 µm Shaped deposition (Laser-Induced Forward Transfer) Thin film machining Diamond 190nm 2 µm Sub-wavelength Surface modulation Towards 3D printing

high-precision gratings 40,000 high-precision gratings per cm2 2.06 μm period 2.13 μm period 20 μm 20 μm 5 mm

High-Value Object Marking 3 mm 2 cm 1 cm 1 mm

Advanced Techniques Gradient Intensity Mirrors are on (+12º) or off (-12º) So, we use careful on/off distribution Modulated surfaces via single laser pulses. Each pulse is different Used for flexible bio-friendly surfaces Beam Translation Movement stages are effective over long distances Beam translation approach is faster and more accurate for small micron-scale distances Gaussian distribution of on/off mirrors Square beam Square beam instantly shifted ~10μm left Square beam instantly shifted ~10μm up and right

Single pulse 3D machining Out-of-plane intensity projection Advanced Techniques Single pulse 3D machining Laser light diffracts as it propagates (e.g. a square will diffract into a sinc2 profile) Whilst some flexibility is possible, we are ultimately limited by the propagation of light Out-of-plane intensity projection Mirrors are on (+12º) or off (-12º) No direct phase control Out-of-plane imaging Allows square in one plane. Circle in another plane (in theory). 10 µm 20 µm Intensity (square) in projected plane Mirror pattern Spiral from above, cone shape from side

The (Near) Future Just awarded: EPSRC Early Career Fellowship (5 year, £1.0m), developing high-precision laser- based manufacturing processes using beam shaping technologies Collaborations welcome Applications-driven research Pathway to commercialisation? Higher powers, different wavelengths, higher repetition rates, increase efficiency etc.

Conclusions Beam shaping is an exciting enabling- technology for high-precision laser-based manufacturing Some technical considerations (i.e. diffraction) Additive and subtractive laser-based manufacturing Many applications, across photonics and biomedical domains Potential for more advanced techniques that really utilise the flexibility of DLP® technology