Brief history of electronic stereoscopic displays

A brief history of recent developments in electronic stereo- scopic displays is given concentrating on products that have succeeded in the market place and hence have had a significant influence on future implementations. The concentration is on plano-stereoscopic (two-view) technology because it is now the dominant display modality in the market- place. Stereoscopic displays were created for the motion picture industry a century ago, and this technology influenced the development of products for science and industry, which in turn influenced product development for entertainment. © 2012 Society of Photo-Optical Instrumentation Engineers (SPIE). (DOI: Elsewhere in this issue, Vivian Walworth describes the early days of the stereoscopic display medium and its nascent industrial development, especially with regard to polariza- tion as a technique for image selection and the Polaroid Corporation's inestimable contribution. The recording media used was conventional silver halide photography, and great progress was made by workers in the field in perfecting the art of stereoscopic capture and display, including projection, using techniques that remain important, such as image selec- tion by means of circular polarization. The recent growing commercial interest in stereoscopic imaging for entertain- ment is directly linked to electronic displays and digital technology. It is my intention to briefly recap electronic stereoscopic display technology's progress during the past three decades. For stereoscopic displays, as is the case for most engineer- ing and scientific disciplines, progress is usually incremental and advances are dependent on prior art developed by work- ers who, in turn, also owe a debt of gratitude to those who came before them. This is the case for today's electronic stereoscopic displays and related technology. The precursors of modern stereoscopic displays can be found in earlier work using conventional motion picture projectors modified to perform the task of projecting a stereoscopic image on a theater screen. The most relevant work containing seeds that have flowered into modern products is the Teleview sys- tem (Fig. 1). It was created by Laurens Hammond, later to invent the eponymous organ, and introduced at the Selwyn Theatre in Manhattan at the end of 1922. Hammond's pre- cocious device is similar to others described in the patent literature in the decade prior to his commercial exhibition, but his device is important because it is the only one like it seen by paying customers. It used eclipse technology— this term refers to occlusion of successive images in which the images are temporally multiplexed and projected on a screen and then directed to the left and right eyes by means of mechanical shutters. Hammond used interlocked 35 mm projectors with lorgnettes with spinning mechanical shutters for image selection mounted on the back of every seat in the theater, with the lorgnettes' and projectors' shut- ters kept in sync by synchronous AC motors. The mechanical advancement of a motion picture frame takes a relatively long time, whereas certain electronic dis- plays refresh rapidly with only a small interval between frames. This observation was the key to understanding why a single digital projector, using the Texas Instruments digital light processing (DLP) micro-mechanical mirror light engine, is capable of projecting field-sequential stereo- scopic images. Although the results on the screen, in terms of the rapid alternation between left and right frames is the same, in concept, as Hammond's, a single digital projector with suitable selection device technology can take the place of two film projectors. It is this that makes the modern stereo- scopic cinema practical in combination with electro-optical shutters and modulators, which are the key ingredients in most stereoscopic displays.