Injection molding of plastic optical lenses prevails over many other techniques in both efficiency and cost; however, polymer shrinkage during cooling, high level of uneven residual stresses, and refractive index variations have limited its potential use for high precision lens fabrication. In this research, we adopted a newly developed strong graphene network to both plano and convex fused silica mold surfaces and proposed a novel injection molding with graphene-coated fused silica molds. This advanced injection molding process was implemented in the molding of polymer-based plano-concave lenses resulting in reduced polymer shrinkage. In addition, internal residual stresses and refractive index variations were also analyzed and discussed in detail. Meanwhile, as a comparison of conventional injection mold material, aluminum mold inserts with the same shape and size were also diamond machined and then employed to mold the same plano-concave lenses. Finally, a simulation model using moldex3d was utilized to interpret stress distributions of both graphene and aluminum molds and then validated by experiments. The comparison between graphene-coated mold and aluminum mold reveals that the novel injection molding with carbide-bonded graphene-coated fused silica mold inserts is capable of molding high-quality optical lenses with much less shrinkage and residual stresses with a more uniform refractive index distribution.

References

References
1.
Zhang
,
H.
,
Scheiding
,
S.
,
Li
,
L.
,
Gebhardt
,
A.
,
Risse
,
S.
,
Eberhardt
,
R.
,
Tünnermann
,
A.
, and
Allen
,
Y. Y.
,
2013
, “
Manufacturing of a Precision 3D Microlens Array on a Steep Curved Substrate by Injection Molding Process
,”
Adv. Opt. Technol.
,
2
(
3
), pp.
257
268
.
2.
Matsuoka
,
T.
,
Takabatake
,
J.-I.
,
Koiwai
,
A.
,
Inoue
,
Y.
,
Yamamoto
,
S.
, and
Takahashi
,
H.
,
1991
, “
Integrated Simulation to Predict Warpage of Injection Molded Parts
,”
Polym. Eng. Sci.
,
31
(
14
), pp.
1043
1050
.
3.
St. Jacques
,
M.
,
1982
, “
An Analysis of Thermal Warpage in Injection Molded Flat Parts due to Unbalanced Cooling
,”
Polym. Eng. Sci.
,
22
(
4
), pp.
241
247
.
4.
Hastenberg
,
C. H. V.
,
Wildervanck
,
P. C.
,
Leenen
,
A. J. H.
, and
Schennink
,
G. G. J.
,
1992
, “
The Measurement of Thermal Stress Distributions Along the Flow Path in Injection-Molded Flat Plates
,”
Polym. Eng. Sci.
,
32
(
7
), pp.
506
515
.
5.
Yang
,
C.
,
Huang
,
H.
,
Castro
,
J. M.
, and
Yi
,
A. Y.
,
2011
, “
Replication Characterization in Injection Molding of Microfeatures With High Aspect Ratio: Influence of Layout and Shape Factor
,”
Polym. Eng. Sci.
,
51
(
5
), pp.
959
968
.
6.
Haken
,
U.
,
Humbach
,
O.
,
Ortner
,
S.
, and
Fabian
,
H.
,
2000
, “
Refractive Index of Silica Glass: Influence of Fictive Temperature
,”
J. Non-Cryst. Solids
,
265
(
1–2
), pp.
9
18
.
7.
Kakiuchida
,
H.
,
Saito
,
K.
, and
Ikushima
,
A. J.
,
2004
, “
Refractive Index, Density and Polarizability of Silica Glass With Various Fictive Temperatures
,”
Jpn. J. Appl. Phys.
,
43
(
6A
), p.
L743
.
8.
Fotheringham
,
U.
,
Baltes
,
A.
,
Fischer
,
P.
,
Höhn
,
P.
,
Jedamzik
,
R.
,
Schenk
,
C.
,
Stolz
,
C.
, and
Westenberger
,
G.
,
2008
, “
Refractive Index Drop Observed After Precision Molding of Optical Elements: A Quantitative Understanding Based on the Tool–Narayanaswamy–Moynihan Model
,”
J. Am. Ceram. Soc.
,
91
(
3
), pp.
780
783
.
9.
Su
,
L.
, and
Yi
,
A. Y.
,
2012
, “
Finite Element Calculation of Refractive Index in Optical Glass Undergoing Viscous Relaxation and Analysis of the Effects of Cooling Rate and Material Properties
,”
Int. J. Appl. Glass Sci.
,
3
(
3
), pp.
263
274
.
10.
Yang
,
C.
,
Su
,
L.
,
Huang
,
C.
,
Huang
,
H.
,
Castro
,
J. M.
, and
Yi
,
A. Y.
,
2011
, “
Effect of Packing Pressure on Refractive Index Variation in Injection Molding of Precision Plastic Optical Lens
,”
Adv. Polym. Technol.
,
30
(
1
), pp.
51
61
.
11.
Li
,
L.
,
Raasch
,
T. W.
, and
Yi
,
A. Y.
,
2013
, “
Simulation and Measurement of Optical Aberrations of Injection Molded Progressive Addition Lenses
,”
Appl. Opt.
,
52
(
24
), pp.
6022
6029
.
12.
He
,
P.
,
Li
,
L.
,
Yu
,
J.
,
Huang
,
W.
,
Yen
,
Y.-C.
,
James Lee
,
L.
, and
Yi
,
A. Y.
,
2013
, “
Graphene-Coated Si Mold for Precision Glass Optics Molding
,”
Opt. Lett.
,
38
(
14
), pp.
2625
2628
.
13.
Huang
,
W.
,
Yu
,
J.
,
Kwak
,
K. J.
,
Gallego-Perez
,
D.
,
Liao
,
W.-C.
,
Yang
,
H.
,
Ouyang
,
X.
,
Li
,
L.
,
Lu
,
W.
,
Lafyatis
,
G. P.
, and
James Lee
,
L.
,
2013
, “
Atomic Carbide Bonding Leading to Superior Graphene Networks
,”
Adv. Mater.
,
25
(
33
), pp.
4668
4672
.
14.
Zhou
,
W.
,
Raasch
,
T. W.
, and
Yi
,
A. Y.
,
2016
, “
Design, Fabrication, and Testing of a Shack–Hartmann Sensor With an Automatic Registration Feature
,”
Appl. Opt.
,
55
(
28
), pp.
7892
7899
.
15.
Choi
,
D.-S.
, and
Im
,
Y.-T.
,
1999
, “
Prediction of Shrinkage and Warpage in Consideration of Residual Stress in Integrated Simulation of Injection Molding
,”
Compos. Struct.
,
47
(
1–4
), pp.
655
665
.
16.
Yang
,
C.
,
Yin
,
X.
,
Castro
,
J. M.
, and
Yi
,
A. Y.
,
2012
, “
Experimental Investigation of the Mold Surface Roughness Effect in Microinjection Molding
,”
Appl. Mech. Mater.,
138–139
, pp.
1258
1262
.
You do not currently have access to this content.