Evaluation of the key design parameters of liquid crystal tunable lenses for depth-from-focus algorithm

Abstract

Liquid crystal (LC) tunable lenses have been extensively studied and used in various applications, however, most of them have been evaluated regardless of their optical imaging quality, in particular, concerning their intrinsic diffuse scattering. In this paper, we investigate the impact of such impairments when LC lenses are used as tunable elements in a depth-from-focus algorithm (DfF). We attempt to analyze these effects in order to design LC lenses that mitigate their impact on the imaging quality. For this purpose, we designed various lenses to evaluate several parameters such as optical, electrical, manufacturing, etc., according to their implementations in a near-pixel DfF architecture.

A Depth Sensor Based on Transient Property of Liquid Crystal Lens

“…It can be seen that it takes 3.3 s and 1.7 s approximately for the LC lens to switch from the positive state to the negative state and vice versa, respectively. The time needed to collect the images for the depth calculation is only several seconds and is far less than that for the method reported in [10][11][12]. More uniform distance change is observed during switching from positive to negative lens state and frames are captured in the process for depth calculation.…”

“…The voltages were adjusted sequentially to obtain a multi-focus image stack. The method was later followed by Li et al [11] and Emberger et al [12]. The LC lens is slow to respond to voltages.…”

“…The LC lens as a system diaphragm can ensure the consistency of magnification between images. In the DFF method using an LC lens proposed in [10][11][12],…”

Optical performance evaluation and chromatic aberration correction of a focus tunable lens used for 3D microscopy

“…By changing the applied electric field, the effective focal length can be tuned. The concept of focus tunable LC lens was introduced in the late 1970s and is still being extensively studied today [1][2][3][4]. The major drawback of the LC tunable lens is its sensitivity to light polarization, slow in response time and low in optical damage threshold [5].…”