Study of electrowetting prism array for non-mechanical large aperture beam steering device

Abstract

Beam steering means to change the direction of a beam in progress at various angles, and is largely classified into mechanical and non-mechanical methods. Mechanical methods have the advantage of large angle and accurate steering, but are generally heavy, bulky, and consume a lot of power. Non-mechanical methods can overcome the disadvantages of mechanical methods because they are light and compact. Among non-mechanical beam steering, electrowetting-based prisms have been studied for their wide steering angle, high operating speed, and high optical performance, but still have a limitation in that the steering aperture is small. In this dissertation, an electrowetting prism array with a new form factor was developed by analyzing the operating principle and structure of the electrowetting prism and proposing a prism arrangement method. A high optical performance prism array was fabricated by selecting an appropriate chamber material, and by studying processes such as laser cutting, liquid selection, and sealing. In addition, the oil isolation problem inherent in the electrowetting prism structure was solved. The electrowetting prism array produced in this way had a response time of 25ms and a fill factor of 87% when the size of each prism was 7mm. The range of the beam steering angle range is ±9.5° in the vertical and horizontal directions and ±13.2° in the diagonal direction

the curvature of the prism interface and the wavefront aberration are 2151mm and 0.181λ, respectively on average. The developed electrowetting prism array was applied to a three-dimensional beam steering and adaptive foveated display. Three-dimensional beam steering was performed by beamforming through electrode separation and adjustment with a prism array. In the foveated display, the position of the high-resolution display needs to be moved according to the gaze, and this was done through the prism array. A prism array with 70% less chromatic dispersion compared to existing prisms was developed and applied by finding liquid conditions that minimize chromatic aberration.