Abstract: In various embodiments, the disclosed subject-matter includes an optical waveguide for a look-through display is disclosed. The optical waveguide includes a light guiding layer and an anti-contaminant layer. The anti-contaminant layer has substantially no impact on the total internal reflection of light at an interface of the light guiding layer. Other devices and apparatuses are also disclosed.

Abstract: A optical apparatus to display an image to a user is disclosed. The apparatus comprises an image source to generate an image bearing light beam having a first numerical aperture; and a diffuser screen. The diffuser screen is configured to increase the numerical aperture of the image bearing light beam to a second numerical aperture. The diffuser screen comprises a first part comprising: a first face and second face substantially parallel to each other, a first array of a plurality of waveguides forming an optical path between the first face and the second face. A value of an optical property of each of the plurality of waveguides is selected randomly from a set of values of the optical property. The first array of a plurality of waveguides is arranged such that each of the plurality of waveguides has an optical axis that is substantially parallel to it's nearest neighbour.

Abstract: A folded optical arrangement for use in a view-through display to transmit an image from an image source to a user's eye, the arrangement providing a folded optical transmission path and comprising: an optical system having a first optical element comprising a first plurality of optically powered surfaces; and a second optical element comprising at least one optically powered surface, the optical system configured to receive light forming the image from an image source, and to present a virtual image of the image source to the user with an apparent focus between a predetermined distance and optical infinity; wherein the first plurality of optically powered surfaces and the at least one optically powered surface of the second optical element are arranged to define a plurality of interfaces along the folded optical path and wherein a refractive index change at each interface is predetermined to control the direction of light passing through the or each interface; and wherein one surface of the first optical ele

Abstract: A folded optical arrangement for use in a look-through display to transmit an image from an image plane to a user's eye, the arrangement providing a folded optical transmission path and comprising: an optical system having a first optical element comprising a first plurality of optically powered surfaces; and a second optical element comprising at least one optically powered surface, the optical system configured to receive light forming the image from an image source, and to focus the light to have an apparent optical focus between a predetermined distance and optical infinity and output the light; wherein the first plurality of optically powered surfaces and the at least one optically powered surface of the second optical element are arranged to define a plurality of interfaces along the folded optical path and wherein a refractive index change at each interface is predetermined to control the direction of light passing through the or each interface; and wherein one surface of the first optical element and

Abstract: At least one corrosion protection unit is located adjacent to a region of a structure immersed in an electrolyte. Each corrosion protection unit includes a circuit for applying rectified alternating current voltage between the structure and electrodes in the electrolyte. Each corrosion protection unit includes Reference Cells to produce direct current voltage between the Reference Cells and the structure, a measuring circuit coupled to the Reference Cells for measuring the potential between the Reference Cells and the structure, and a control circuit for controlling the level of the rectified alternating current voltage in accordance with the measured potential levels. Corrosion protection units are independent of one another, so that independently established rectified alternating current voltages are applied between different regions of the structure and e first and second corrosion protection units.

Abstract: According to a first aspect of the invention, there is provided a display system, comprising: an angular intensity distribution element, arranged to receive light from one or more sources of light and to effect an angular intensity distribution of the light, the angular intensity distribution element introducing an undesirable feature into a distribution of the light; one or more optical elements located downstream of the angular intensity distribution element, and arranged to effect an angular and/or spatial intensity distribution of the light prior to display of the light to a user of the system; and a spatial filter, located downstream of the angular intensity distribution element, and arranged to receive the light and to at least partially correct for the undesirable feature (e.g. at least partially reduce and/or eliminate the feature or a related effect).

Abstract: At least one corrosion protection unit is located adjacent to a region of a structure immersed in an electrolyte. Each corrosion protection unit includes a circuit for applying rectified alternating current voltage between the structure and electrodes in the electrolyte. Each corrosion protection unit includes Reference Cells to produce direct current voltage between the Reference Cells and the structure, a measuring circuit coupled to the Reference Cells for measuring the potential between the Reference Cells and the structure, and a control circuit for controlling the level of the rectified alternating current voltage in accordance with the measured potential levels. Corrosion protection units are independent of one another, so that independently established rectified alternating current voltages are applied between different regions of the structure and e first and second corrosion protection units.

Abstract: Light 63 incident on a first screen 61 is dispersed by the optical properties of the polymer dispersed liquid crystal material associated with the first screen 61 at a given half scatter angle 64 to provide an interim diffused pupil 65, which is incident on the second screen 62. Diffused light incident on the second screen 62 is diffused by the optical properties of the polymer dispersed liquid crystal material associated with the second screen 62 by a given half scatter angle 66 to produce the diffused pupil 60. Conducting material associated with the first and second screens 61, 62 is controlled by a controller 67 to vary the half scatter angles 64 and 66 out of phase with one another, in a manner to maintain a substantially constant diffused pupil 60.

Abstract: A head up display signal processing system is disclosed. The system comprises an image projector for projecting an image onto a screen, the screen being partially reflective and partially transmissive. The system is operable to provide a separate optical element at a plurality of locations upon the screen, wherein each element comprises an optical phase representative of the location of the element upon the screen, such that the combination of optical elements is arranged to produce an optical hologram upon the screen.

Abstract: A head up display apparatus is disclosed for projecting an image upon a screen. The apparatus comprises a signal processing system, comprising an image projector for projecting an image to a partially reflective screen, the screen being configured substantially in front of an eye of a user of the display apparatus. The apparatus further comprises a beam steering arrangement for steering the projected image substantially at an exit pupil of the system, upon the screen, and a pupil tracking arrangement for tracking a pupil of the users eye such that the projected image remains directed at the pupil of the user as the user adjusts their line of sight.