Abstract: A variable focus lens system can include a variable focus lens, one or more electrodes, a signal generator configured to supply voltage to the one or more electrodes to vary the focal length of the variable focus lens, and a controller configured to apply a voltage to the one or more electrodes and receive information indicative of a capacitance that results from the applied voltage. The controller can be configured to determine a temperature of the variable focus lens based at least in part on the capacitance or applied voltage. The variable focus lens system can include a temperature sensor, and the controller can be configured to receive temperature information from the temperature sensor and calibrate the temperature sensor based at least in part on the received temperature information, the applied voltage, and the received capacitance information.