Compression molding is an effective high volume and net-shape fabrication method for aspherical lenses and precision glass optical components in general. Geometrical deviation (or curve change as often referred to in industry) incurred during heating, molding, and cooling processes is a critically important manufacturing quality parameter. In the compression glass molding process, there are many factors that could lead to curve change in final products, such as thermal expansion, stress and structural relaxation, and inhomogeneous temperature distribution inside the molding machine. In this research, an integrated numerical simulation scheme was developed to predict curve change in molded glass aspherical lenses. The geometrical deviation in the final lens shape was analyzed using both an experimental approach and a numerical simulation with a finite element method program. Specifically, numerical simulation was compared with experimental results to validate the proposed manufacturing approach. The measurements showed that the difference between numerical simulation and experimental results was less than $2 μm$. Based on the comparison, the mold curve was revised using numerical simulation in order to produce more accurate lens shapes. The glass lenses molded using the compensated molds showed a much better agreement with the design value than the lenses molded without compensation. It has been demonstrated in this research that numerical simulation can be used to predict the final geometrical shape of compression molded precision glass components. This research provided an opportunity for optical manufacturers to achieve a lower production cost and a shorter cycle time.

1.
Maschmeyer
,
R. O.
,
Andrysick
,
C. A.
,
Geyer
,
T. W.
,
Meissner
,
H. E.
,
Parker
,
C. J.
, and
Sanford
,
L. M.
, 1983, “
Precision Molded Glass Optics
,”
Appl. Opt.
,
22
, pp.
2413
2415
. 0003-6935
2.
Yi
,
A. Y.
, and
Jain
,
A.
, 2005, “
Compression Molding of Aspherical Glass Lenses—A Combined Experimental and Numerical Analysis
,”
J. Am. Ceram. Soc.
0002-7820,
88
(
3
), pp.
579
586
.
3.
Fischer
,
R. E.
, and
Hileman
,
D.
, 2004, “
Bending to Demand
,”
SPIE's Oemagazine
,
116
, pp.
25
27
.
4.
Soules
,
T. F.
,
Busbey
,
R. F.
,
Rekhson
,
S. M.
,
Markovsky
,
A.
, and
Burke
,
M. A.
, 1987, “
Finite Element Calculation of Stresses in Glass Parts Undergoing Viscous Relaxation
,”
J. Am. Ceram. Soc.
0002-7820,
70
(
2
), pp.
90
95
.
5.
Moynihan
,
G. T.
,
Easteal
,
A. J.
, and
DeBolt
,
M. A.
, 1976, “
Dependence of the Fictive Temperature of Glass on Cooling Rate
,”
J. Am. Ceram. Soc.
0002-7820,
59
(
1–2
), pp.
12
15
.
6.
Dang
,
C. P.
, and
Brüggemann
,
D.
, 2005, “
Optimizing the Cooling Parameters for Annealing of Glass Bottles by Stress Simulation According to the Viscoelastic Theory
,”
Glass Sci. Technol. (Offenbach, Ger.)
0946-7475,
78
(
4
), pp.
141
145
.
7.
Sellier
,
M.
,
Breitbach
,
C.
,
Loch
,
H.
, and
Siedow
,
N.
, 2007, “
,”
Proc. Inst. Mech. Eng., Part B
0954-4054,
221
, pp.
25
33
.
8.
Jain
,
A.
,
Firestone
,
G. C.
, and
Yi
,
A. Y.
, 2005, “
Viscosity Measurement by Cylindrical Compression for Numerical Modeling of Precision Lens Molding Process
,”
J. Am. Ceram. Soc.
0002-7820,
88
(
9
),
2409
2414
.
9.
Scherer
,
G. W.
, 1986,
Relaxation in Glass and Composites
,
Wiley
,
New York
.
10.
Jain
,
A.
, and
Yi
,
A. Y.
, 2005, “
Numerical Modeling of Viscoelastic Stress Relaxation During Glass Lens Forming Process
,”
J. Am. Ceram. Soc.
0002-7820,
88
(
3
), pp.
530
535
.
11.
Chui
,
G. K.
, and
Gardon
,
R.
, 1969, “
Interaction of Radiation and Conduction in Glass
,”
J. Am. Ceram. Soc.
,
52
(
10
), pp.
548
553
. 0002-7820
12.
Viskanta
,
R.
, and
Lim
,
J. M.
, 2001, “
Theoretical Investigation of Heat Transfer in Glass Forming
,”
J. Am. Ceram. Soc.
,
84
(
10
), pp.
2296
2302
. 0002-7820
13.
Endrys
,
J.
, 1999, “
Measurement of Radiative and Effective Thermal Conductivity of Glass
,”
Proceedings of the 5th ESG Conference: Glass Science and Technology for the 21st Century
,
A.
Helebrant
,
M.
Maryska
, and
S.
Kasa
, eds.,
Czech Glass Society
,
Prague, Czech Republic
, pp.
A5.10
A5.17
.