A varifocal system comprises a stacked first-type liquid crystal (LC) lens structure and a stacked second-type LC lens structure in optical series. The stacked first-type LC lens structure includes a plurality of first-type LC lenses, and a first-type LC lens provides continuously variable optical states in a first step resolution. The stacked second-type LC lens structure includes a plurality of second-type LC lenses and provides a plurality of optical states in a second step resolution. The first step resolution is smaller than the second step resolution, such that when the stacked second-type LC lens structure is switched between two optical states, the first-type LC lenses provide a continuous adjustment of optical power between the two optical states. The stacked first-type LC lens structure and the stacked second-type LC lens structure together provide a continuous adjustment range of optical power for the varifocal system.