A Resolution-Enhanced Digital Micromirror Device (DMD) Projection System

Abstract

In this paper we present a resolution-enhanced system for digital micromirror device (DMD) projected images by utilizing time multiplexing and birefringence in order to achieve this with static components only. This provides a less expensive solution than reducing the size of the hardware pixels and can also be applied to higher resolution displays, as and when, these become available. Birefringent materials have different refractive indices for linearly polarized light with orthogonal polarization directions. A high-resolution projected image can be observed by overlapping two or three native resolution images at shifts of one half or one third of a DMD pixel diagonal respectively on successive frames. The optical components comprise a custom-made quartz plate as the birefringent component and an off-the-shelf twisted nematic liquid crystal display (TN-LCD) screen as a polarization rotator that is synchronized with the DMD frame rate. This paper covers the principle of operation and the system design. The functioning of the display is verified using enlarged images of the letter 'R' and a checkerboard pattern that are formed from a small number of DMD pixels.