Abstract: A head mountable apparatus is described for transmitting an image to the user's eye using switchable holographic optical elements. In one embodiment, an optical system is provided that is configured to receive an image provided by an image generator and which forms a light path along which light is transmitted from the image generator to an eye of the user. The optical system includes a first switchable holographic optical element configured to operate in an active state or an inactive state, wherein the first switchable holographic optical element is configured to diffract the image light incident thereon when the first switchable holographic optical element operates in the active state, and wherein the first switchable holographic optical element transmits the image light incident thereon without substantial alteration when the first switchable holographic optical element operates in the inactive state.

Abstract: Disclosed is an apparatus and method of illuminating an image display via an electrically switchable holographic optical element. The method includes a first electrically switchable holographic optical element (ESHOE) receiving illumination light. The first ESHOE comprises oppositely facing front and back surfaces. The first ESHOE focuses a first component (e.g., p-polarized blue light) of the illumination light while transmitting the remaining components of the illumination light without substantial alteration. An image display is provided and receives the focused first component. In response to receiving the focused first component, the image display emits image light. The first ESHOE receives and transmits this image light without substantial alteration. In one embodiment, the focused first component emerges from the first ESHOE at the back surface thereof, and the first ESHOE receives the image light at the back surface.

Abstract: Disclosed is an illumination system using optical feedback to maintain a predetermined illumination output. The illumination system employs an electrically controllable optical filter for filtering light incident thereon. The illumination system also includes a light detector for detecting at least a portion of the light filtered by the electrically controllable optical filter. The light detector is in data communication with the electrically controllable optical filter. Some or all light filtered by the electrically controllable optical filter is detected by the light detector, which, in turn generates a corresponding signal that is compared to at least one predetermined value. If the signal generated by the light detector differs when compared to the at least one predetermined value, one or more filtering characteristics of electrically controllable optical filter are varied which, in turn, varies the amount of light filtered by the electrically controllable optical filter.

Abstract: Disclosed is a method for calculating relative phase between channels of a multi-sensor tracking device. The relative phases may be used to calibrate the multi-tracking sensor device to perform more accurately. The method involves recording a plurality of first signals generated by a first channel of the multi-sensor tracking device. The plurality of first signals are generated during a movement of the multi-sensor tracking device. Typically, the multi-sensor tracking device includes several channels, each one of which includes at least one sensor for sensing movement with respect to a corresponding axis. Concurrent to recording of plurality of first signals, a plurality of second signals generated by a second channel of the multi-sensor tracking device, is recorded. The plurality of second signals are generated during the movement of the multi-sensor tracking device.

Abstract: Disclosed is a method for calculating relative phase between channels of a multi-sensor tracking device. The relative phases may be used to calibrate the multi-tracking sensor device to perform more accurately. The method involves recording a plurality of first signals generated by a first channel of the multi-sensor tracking device. The plurality of first signals are generated during a movement of the multi-sensor tracking device. Typically, the multi-sensor tracking device includes several channels, each one of which includes at least one sensor for sensing movement with respect to a corresponding axis. Concurrent to recording of plurality of first signals, a plurality of second signals generated by a second channel of the multi-sensor tracking device, is recorded. The plurality of second signals are generated during the movement of the multi-sensor tracking device.

Abstract: Disclosed is an apparatus and method of illuminating an image display via an electrically switchable holographic optical element. The method includes a first electrically switchable holographic optical element (ESHOE) receiving illumination light. The first ESHOE comprises oppositely facing front and back surfaces. The first ESHOE diffracts a first component (e.g., p-polarized blue light) of the illumination light while transmitting the remaining components of the illumination light without substantial alteration. An image display is provided and receives the diffracted first component. In response to receiving the diffracted first component, the image display emits image light. The first ESHOE receives and transmits this image light without substantial alteration.

Abstract: Disclosed is an apparatus and method of illuminating an image display via an electrically switchable holographic optical element. The method includes a first electrically switchable holographic optical element (ESHOE) receiving illumination light. The first ESHOE comprises oppositely facing front and back surfaces. The first ESHOE diffracts a first component (e.g., p-polarized blue light) of the illumination light while transmitting the remaining components of the illumination light without substantial alteration. An image display is provided and receives the diffracted first component. In response to receiving the diffracted first component, the image display emits image light. The first ESHOE receives and transmits this image light without substantial alteration.

Abstract: A method of managing latency in a system for tracking movement of an object includes providing a request-and-response mechanism for transferring tracking data across a communications link. In one embodiment, the object for which movement is to be tracked is a human head and the system is a virtual reality system. Packets of the tracking data may be generated using a conventional sensor processing technology, but the packets are transferred via the communications link to an image processing capability, such as that of a host computer. The packets are generated at a fixed sample rate that is asynchronous with respect to the processing requirements of the host computer. When the host computer is available for fresh tracking data, a packet-transfer request is transmitted to the source of the packet. Latency can be reduced by enabling the source of the packets to anticipate reception of a packet-transfer request.

Abstract: Holographic optical elements (HOEs) can be used in systems and methods for providing illumination and for projecting images. The HOEs may be switchable HOEs, whose diffractive properties can be controlled. Described herein is a method of combining light from two or more illumination sources. In one embodiment, a reflection-type HOE is illuminated by the first illumination source. The HOE diffracts light from the first illumination source into an output direction. Light from the second illumination source is transmitted through the HOE and onto a reflective optical element, which reflects the light back through the HOE and into the same output direction. Also described is a projection system that uses two or more HOEs to combine two or more colors of light for use by a single image display. The system includes one or more light sources, an image display (such as a reflective or transmissive LCD display or a MEMS display, for example), and a first and a second HOE.

Abstract: A projection system and a method of displaying a projected input image on a projection screen of the system utilize one or more reconfigurable holographic optical elements (HOEs) to optically manipulate propagating light in the system. The reconfigurable HOEs may be configured to perform simple optical functions that are commonly associated with traditional optical devices, such as lenses, prisms and mirrors. However, the reconfigurable HOEs may also be configured to perform sophisticated optical manipulations, such as varying the light intensity toward a specific direction and generating virtual (holographic) images. Each reconfigurable HOE includes a hologram that is sandwiched between two electrode layers. The hologram is a holographic photopolymeric film that has been combined with liquid crystal. The hologram has an optical property that changes in response to an applied electrical field.

Abstract: Holographic optical elements (HOEs) can be used in systems and methods for providing illumination and for projecting images. The HOEs may be switchable HOEs, whose diffractive properties can be controlled. Described herein is a method of combining light from two or more illumination sources. In one embodiment, a reflection-type HOE is illuminated by the first illumination source. The HOE diffracts light from the first illumination source into an output direction. Light from the second illumination source is transmitted through the HOE and onto a reflective optical element, which reflects the light back through the HOE and into the same output direction. Also described is a projection system that uses two or more HOEs to combine two or more colors of light for use by a single image display. The system includes one or more light sources, an image display (such as a reflective or transmissive LCD display or a MEMS display, for example), and a first and a second HOE.

Abstract: An interpolation filter is used in television standards conversion to decimate an input sequence of higher definition signals into an output sequence of lower definition signals. The filter is partitioned into a plurality of computational stages. Within each stage, the decimation coefficients are stored in a random access coefficient memory and applied to a multiplier to generate the product of a digital input signal and a stored coefficient. The RAM is operable in two modes: a first mode in which new sets of coefficients are serially input to the RAM during the field blanking period and a second mode in which different stored coefficients are output to the multiplier for consecutive digital signals to effect a non-integer decimation ratio.