Researchers from the National University of Singapore have created an endoscopic probe that delivers adjustable-focus capabilities in a slimmer package. The miniature and solid tunable-lens technology enables compact optical zoom with autofocus capability. The device switches from a wide field-of-view to a clear, high-resolution close-up view without moving the endoscope probe.
The lens system contains two transparent polymer plates, each with one flat surface and one freeform curved surface. The freeform surfaces are inverses of each other. When the transparent plates are perfectly aligned with the freeform surfaces, they behave as one unit without any focusing power — any wave phase shift induced by one is cancelled out by the other.
When the plates are slightly offset in a sideways direction, however, they refract light like a traditional lens. Two piezoelectric benders drive these minute shifts in lens placement, controlling the focusing power of the endoscope by changing the degree of displacement. The image is then transmitted to an external camera monitored by a technician.
The resulting device is far less bulky than existing high-magnification endoscopes.
The endoscope, still in its early development stages, has not yet been tested in a clinical setting. The next step for the Singapore engineers will be to incorporate multiple tunable lenses into the system so that it has not just adjustable focus, but also full optical zooming capabilities.