Recently liquid-based optical devices are emerging as attractive components in three-dimensional (3D) display for its
compact structure and fast response time. Among them an electrowetting prism array is one of the promising 3D devices.
It steers a beam, which enables to provide corresponding perspectives to observer. For high quality autostereoscopic 3D
displays the important factors are the beam steering angle and the beam profile, the optical characteristics. In this paper,
we propose a method to measure the optical characteristics of the liquid prism and show experimental results on our
prototype electrowetting prism array, which consists of prisms with 200um by 200um size. A modified 4-f system is
adopted for the proposed method. It provides two kinds of information of the optical characteristics of the liquid prism at
the image plane and at the Fourier plane. First, the proposed measurement setup magnifies the image of the liquid micro
prism array so that we can observe the status of the each prism array directly with bare eye and align a mask easily for
selecting a prism to be examined at the image plane. Secondly, the steering angle can be calculated by measuring the
displacement of the beam at the Fourier plane, where the angular profiles that have important information on the oilwater
interface is observed precisely. The principle of the proposed method will be explained, and the measured optical
characteristics from experimental results on the liquid prism we fabricated will be provided, which proves the validity of
the measurement method.