Image-based Response Measurement of Liquid Lens and Iterative Calibration of Scanning Focus Tracking for Dynamic Iris Authentication

There is an increasing demand for iris authentication in dynamic environments, such as when people are walking. High-speed focus control using a liquid lens is one solution for such dynamic iris authentication, but it is necessary to increase the frequency of capturing in-focus iris images considering the blinking of the eye. In this paper, we propose a simple response measurement method of the liquid lens using a large and tilted checker pattern, and an iterative calibration method of sinusoidal parameters in scanning focus tracking control using the liquid lens. We have experimentally confirmed step and sinusoidal responses of the liquid lens, and demonstrated sufficient and high-frequency AR marker (alternative to iris) recognition performance of the scanning focus tracking control for manual marker movement and zooming adjustments with a motorized lens.