Tunable acoustic gradient lens system with amplitude adjustment corresponding to z-height as indicated by calibration data

Abstract

A variable focal length lens system includes a tunable acoustic gradient (TAG) lens; a TAG lens controller; a light source; a camera; and processor(s) configured to: (a) drive a periodic modulation of the TAG lens optical power, using a first amplitude driving signal that provides a first amplitude of the periodic modulation at a resonant frequency of the TAG lens, the first amplitude corresponding to a first focal Z range extending between peak focus distances Zmax+ and Zmax−, wherein the first amplitude driving signal is selected based on a first target focus distance Ztarget−1 and calibration data which relates different amplitude driving signals to different target focus distances Ztarget−i; and (b) operate the light source and camera to expose an image using at least one exposure increment wherein the focus distance during the exposure increment moves over a first exposure Z range that includes target focus distance Ztarget−1.