Digital Micromirror Devices for rapid fabrication of large-area laser-ablated multicolour-grating patterns

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Outline

• Introduction to digital mirror devices (DMD)

• Using a DMD for laser-ablation

• Fabrication of multi-colour surfaces

• Replication of a Morpho butterfly

• Conclusions

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Digital Mirror Device (DMD)

• Used in majority of projectors

• Array of individually controlled ~10μm width mirrors

• Can be used as an intensity spatial light modulator (SLM)

• Fast switching speed (>30kHz)

Schematic of a section of the digital mirror device (actual

model used: Texas Instruments DLP3000, 608 x

684 mirrors)

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• Energy density on sample is 1-50J/cm2

• Energy density on DMD is ~1mJ/cm2

• Well below damage threshold of DMD due to magnification

Experimental schematic

Sample fabrication schematic

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• Each laser pulse is shaped to a different pattern

• The sample is continuously translated

input

laser pulses

array of mirrors,showing the pattern

(the DMD)

focussingobjective

spatially-shaped

laser pulses

sample iscontinuouslytranslated

sam

ple

movem

ent

dir

ect

ion

Process repeated to make 2D arrays

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dire

ction o

f

stage m

ovem

ent

• After each line of letters, we start again on an adjacent line, to build up 2D arrays

50µm 10µm

Not letters but gratings, where each grating can have a different period

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• Each grating is 30 by 30µm and will diffract different colours of light to different angles

• We build up an array of 10,000s, over cm-squared regions

• Result is that the material surface appears to be coloured 10µm

50µm

Security and marking applications

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1mm

1mm

3mm

Replication of a Morpho butterfly

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Nature

Fabricated

SEM image Photograph

1µm

10µm2mm

Conclusions• Fabrication of cm-squared regions in 15 minutes (with

faster stages less than 1 minute)

• Diffraction-limited writing resolution

• Can be used to make a surface appear to be multi-coloured

• Applications in security / marking

This work was supported under EPSRC (grant number EP/L022230/1)

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