Switchable pattern illuminator via liquid crystal geometric phase microlens array

Abstract

We propose a novel 2-in-1 pattern projector, which consists of a Dot projector and an LC diffuser. The LC diffuser is made of switchable Microlens Arrays (MLA) based on geometric phase. The LC diffuser can switch between "no lens power" and "MLA" mode. In "no lens power" mode, the Dot pattern is not affected by the LC diffuser. In "MLA" mode, the focused Dot pattern is "blurred" by the MLA, which generates the Flood pattern. The eigen mode of geometric phase MLA is carefully designed to achieve polarizer free modulation. We implement this novel modulation concepts with the world smallest and 1 st ever reflowable LC cell. We made a record of 3x3mm LC cell with our in-house IJP system. The optical efficiency is over 95%, and the switching time is less than 5ms.

Reflowable liquid crystal geometric phase element for vertical cavity surface emitting laser projector

“…3 The POM observation of LC diffuser under cross polarizer with green light source. 10 Fig. 2 3D sensing module prototype with two-in-one pattern projector.…”

“…Photoalignment is the key technology to realize geometric phase LC alignment. According to prior art, 10 a grating pattern illumination is required to create LC geometric phase. First, we setup an interferometer 11 , 12 to create grating pattern on photoalignment layer on glass.…”

“…Fig.4The projected pattern by switchable VCSEL dot projector with LC diffuser 10. (a) Flood pattern when LC diffuser is voltage off.…”