Quinn Y. J. Smithwick

Anisotropic leaky-mode modulator for holographic video displays

Every holographic video display is built on a spatial light modulator, which directs light by diffraction to form points in three-dimensional space. The modulators currently used for holographic video displays are challenging to use for several reasons: they have relatively low bandwidth, high cost, low diffraction angle, poor scalability, and the presence of quantization noise, unwanted diffractive orders and zero-order light. Here we present modulators for holographic video displays based on anisotropic leaky-mode couplers, which have the potential to address all of these challenges. These modulators can be fabricated simply, monolithically and at low cost. Additionally, these modulators are capable of new functionalities, such as wavelength division multiplexing for colour display. We demonstrate three enabling properties of particular interest—polarization rotation, enlarged angular diffraction, and frequency domain colour filtering—and suggest that this technology can be used as a platform for low-cost, high-performance holographic video displays.

Bokode: imperceptible visual tags for camera based interaction from a distance

We show a new camera based interaction solution where an ordinary camera can detect small optical tags from a relatively large distance. Current optical tags, such as barcodes, must be read within a short range and the codes occupy valuable physical space on products. We present a new low-cost optical design so that the tags can be shrunk to 3mm visible diameter, and unmodified ordinary cameras several meters away can be set up to decode the identity plus the relative distance and angle. The design exploits the bokeh effect of ordinary cameras lenses, which maps rays exiting from an out of focus scene point into a disk like blur on the camera sensor. This bokeh-code or Bokode is a barcode design with a simple lenslet over the pattern. We show that a code with 15μm features can be read using an off-the-shelf camera from distances of up to 2 meters. We use intelligent binary coding to estimate the relative distance and angle to the camera, and show potential for applications in augmented reality and motion capture. We analyze the constraints and performance of the optical system, and discuss several plausible application scenarios.

Holographic video display based on guided-wave acousto-optic devices

We introduce a new holo-video display architecture (Mark III) developed at the MIT Media Laboratory. The goal of the Mark III project is to reduce the cost and size of a holo-video display, making it into an inexpensive peripheral to a standard desktop PC or game machine which can be driven by standard graphics chips. Our new system is based on lithium niobate guided-wave acousto-optic devices, which give twenty or more times the bandwidth of the tellurium dioxide bulk-wave acousto-optic modulators of our previous displays. The novel display architecture is particularly designed to eliminate the high-speed horizontal scanning mechanism that has traditionally limited the scalability of Scophony- style video displays. We describe the system architecture and the guided-wave device, explain how it is driven by a graphics chip, and present some early results.

Progress in holographic video displays based on guided-wave acousto-optic devices

The novel frequency-multiplexed modulator architecture of the MIT Mark III holo-video display poses a significant challenge in generation of appropriate video signals. Unlike in our previous work, here it is necessary to generate a group of adjacent single-sideband RF signals; as this display is intended to be manufacturable at consumer-electronics prices we face the added requirement of compact and inexpensive electronics that are compatible with standard PC graphics processors. In this paper we review the goals and architecture of Mark III and then describe our experiments and results in the use of a hardware/software implementation of Weavers single-sideband modulation method to upconvert six 200MHz baseband analog video signals to a set of RF signals covering a nearly contiguous 1GHz range. We show that our method allows efficient generation of non-overlapping signals without aggressive filtering.

P-3: Evaluation of Rendering Algorithms for Presenting Layered Information on Holographic Displays

This paper proposes evaluation of rendering methods for holographic display allowing a viewer to use monocular information to selectively focus on parts of the display volume. We describe an experiment for comparatively evaluating human performance across different holographic rendering methods, by requiring the identification of overlapping letters separated in depth.

The Seeing Machine Camera: An Artistic Tool for the Visually Challenged Conceived by a Visually Challenged Artist

ABSTRACT The Vision Group at the Center for Advanced Visual Studies (CAVS) at the Massachusetts Institute of Technology (MIT) has developed the Seeing Machine Camera (SMC) under the direction of Elizabeth Goldring, a visually challenged artist. The SMC is an innovative tool that enables artistic expression for those with decreased vision. The camera enhances the ability to see the face of a loved one, look at a painting in a museum, photograph landscapes or create digital artwork. For visually challenged artists who may feel isolated from their visual world, the SMC provides an opportunity to connect to the people around them, enjoy a greater sense of independence and expand their creativity.

Making Holographic Television a Consumer Product

Recent holographic video research at the MIT Media Laboratory has focused on making a display suitable for consumer use. We discuss our new display architecture, and its novel electro-optical aspects.