可変焦点レンズを用いた長焦点深度視覚機構

抄録

We have developed a microscope using a dynamic focusing lens suitable for micro parts assembling. With the microscope, real-time observation of three-dimensional micro parts was achieved. The dynamic focusing lens consists of a thin glass diaphragm having a specific thickness profile, a metal diaphragm with a glass plate, transparent liquid, and PZT unimorph actuators. When the actuators push the metal diaphragm, the pressure of the transparent liquid bends the glass diaphragm. Therefore, the curvature of the lens is changed according to the applied voltage of the actuators. When the actuator is activated at high frequency, the focal plane of the lens is rapidly shifted, and many images of different focus are obtained in a short time. When the lens is activated at 60Hz, an image of the entire object is obtained, as if the depth of field is expanded. It is caused by the afterimage effect of the human eye. By the mechanism, the depth of field is expanded about four times.