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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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