Formation of a variable focus lens by elastomer compression

Abstract

A lens was formed from the compression of a thick layer of polydimethylsiloxane (PDMS) elastomer. The focal length of the lens was then measured at various depths of depression. A simulation of the lens surface profile was made, and the polynomial fit of the profile indicated that the initial shape was essentially parabolic, and contribution from the quartic term was found to increase with depression depth. Ray tracing was conducted on the fitted curve, and the predicted focal length was found comparable to the measured at high depression depths. The lens was able to resolve about 8 lines/mm at 20 mm focal distance. A clear image was observed near the optical axis of the lens but there was pin-cushion distortion at the periphery..