An endoscope utilizing tunable-focus microlenses actuated through infrared light

We report on a prototype endoscope with tunable-focus liquid microlenses actuated through infrared (IR) light integrated at its distal end. Tunable-focus microlenses scanning the areas of interest with minimal movements of the scopes themselves would greatly advance endoscopy. Multiple IR light-responsive hydrogel posts were used to tune the focal length of the microlens, which were formed by a curved water-oil meniscus. The fabrication and actuation of the hydrogel posts were realized through light transmitted via optical fibers. The focal length varied from 52 mm to 8 mm. Focused images were obtained from an image fiber bundle. A microlens array with larger depth of focus and view of field could be potentially utilized.