Two-Photon Polymerization – 3D Printing on µm-scale
Basic principle: Illumination of (liquid) UV resist (λ) with fs-laser pulses (2λ)
non-linear absorption confined to focal spot
localized polymerization reaction (solidification)
1PP
2PP
3D movement of focal volume
+ removing liquid resist
Inherent 3D µ-structures
3D model
2D contour
Resulting structure
10 µm
slicing in z
© Fraunhofer
hatching in x/y
Two-Photon Polymerization for microlenses
Fabrication of arbitrarily shaped microoptical elements and arrays of elements
Different types and sizes of elements on one substrate possible
deviations 2D
12
60
10
50
8
40
Y / µm
Height / µm
Example: Aspheric microlens
6
4
10
20
Deviations / µm
0
0.5
Fit (sphere)
Fit (asphere)
0.0
-0.5
20
30
40
50
X / µm
© Fraunhofer
30
20
Data
Fit (sphere)
Fit (asphere)
2
60
RMS: 76nm
70
80
30
40
50
60
X / µm
70
80
Two-Photon Polymerization for microlenses
Fabrication of arbitrarily shaped microoptical elements and arrays of elements
Different types and sizes of elements on one substrate possible
Example: Microlens for the generation of a ring-shaped focal volume
Testrays
Surface
SEM
80
z / µm
Design
100
60
40
20
0
-40
-20
0
r / µm
20
40
150 µm
40
y / µm
AFM
5 µm
20
0
© Fraunhofer
0
20
x / µm
40
0 µm
50 µm
Two-Photon Polymerization for microlenses
Fabrication of arbitrarily shaped microoptical elements and arrays of elements
Different types and sizes of elements on one substrate possible
Example: Microlens for the generation of a ring-shaped focal volume
Characterization of focal intensity distribution
© Fraunhofer
Two-Photon Polymerization for microlenses
Fabrication of arbitrarily shaped microoptical elements and arrays of elements
Different types and sizes of elements on one substrate possible
Example: Lens array fabricated using galvoscanner technology
34 x 34 lenses with 120 µm pitch
→ 4.08 x 4.08 mm²
500 µm
10 µm
optical
topography
7.25 µm
0 µm
© Fraunhofer
Two-Photon Polymerization for microlenses
Fabrication of arbitrarily shaped microoptical elements and arrays of elements
Different types and sizes of elements on one substrate possible
Example: Large lens array; 6.500 lenses; 15 x 10 mm², Ø = 60 µm; 150 µm pitch
© Fraunhofer
Two-Photon Polymerization for microlenses
Fabrication of arbitrarily shaped microoptical elements and arrays of elements
Different types and sizes of elements on one substrate possible
Example: Large lens array with variable pitch; 3.500 lenses; 37.5 x 10 mm²
© Fraunhofer
Two-Photon Polymerization for microlenses
Fabrication directly on chips…
… and on any desired position of a substrate
Ø = 50 µm; ROC = 60 µm
P = 7 mW
6 x 6 lenses with Pitch = 50 µm
Variable laser powers: 10, 8, 7, 6, 5 mW
P = 6 mW
P = 5 mW
© Fraunhofer
ORMOCER®s – High performance materials for optics
Excellent optical properties
Hybrid polymers
(ORMOCER®s)
Adjustable refractive index
Low losses
Refractive index
1.48 – 1.59
Low surface roughness
Layer thickness
100 nm – 1 mm
Yellowing
Low
Chemicals
Roughness (rms)
0.5 nm – 10 nm
Temperature
Thermal stability (O2)
300 °C – 350 °C
Sterilization (e.g. autoclaving)
Processes
Spin-Coating + UV
Litho, NIL; TPA; InkJet, Screen-printing
High stability against
Biocompatible
Low water uptake
Barrier properties
© Fraunhofer