Adjustable lens system for real-time applications

Abstract

An adjustable fluid type lens system is provided that allows e.g. ultrasound imaging through the lens during adjustment of the lens. The lens includes a container enclosing two immiscible fluids, e.g. water and oil, being in contact with each other at an interface. Incoming waves are then refracted at this interface. The shape of the interface, and thereby the refraction property, is adjustable by adjusting a voltage applied to the lens. The two fluids are selected such that they together exhibit a mechanical damping which is critical or near critical. A control circuit generates the electric voltage for adjusting the refraction from one value to another, the control circuit being arranged to change the electric voltage such that a rate of voltage change is limited to avoid oscillation of the interface, thereby adjusting refraction of incoming waves at the interface in a continuous manner. This makes it possible to use the lens while it is during adjustment from one refraction value to another, since the interface shape will at all time during the adjustment have a controlled shape. The voltage can be either a continuous voltage or a discrete stepwise (digital) voltage which is just controlled with respect to step size and temporal extension of the steps. The lens system has a number of applications e.g. within the medical field, e.g. for 'on the fly' high speed ultrasound imaging, or for ultrasound ablation applications where ablation can be performed during adjustment of the lens to follow a pre-defined trajectory.