Abstract:
A compact high quality and lightweight symbol generator (3) for projecting symbolic information into the field of view of a viewfinder is provided. The symbol generator (3) comprises at least one Electrically Switchable Bragg Gratings (ESBG) (13a, 12, 13b) device sandwiched between a pair of transparent plates (10, 11) which together function as a total internal reflection lightguide, switching electrodes and means for coupling illumination into the light guide. Each ESBG device contains information encoded in a multiplicity of separately switchable grating regions (12). A plurality of independently switchable transparent electrodes elements, substantially overlay the separately switchable grating regions (12).
Abstract:
There is provided a method of fabricating an improved HPDLC transparent symbolic data display for projecting symbology into the field of view of a viewing device in which the HPDLC is localized to the display regions covered by the symbols. In a first step, a substrate to which an anti reflection coating and a transparent electrode layer have been applied is provided. In a second step, portions of said transparent electrode layer are removed to provide a patterned electrode layer including a symbol pad. In a third step, a layer of UV absorbing dielectric material is deposited over said patterned electrode layer. In a fourth step, the portion of said UV absorbing dielectric material overlapping said symbol pad is removed. In a fifth step, a second substrate to which an anti reflection coating and a transparent electrode layer have been applied is provided. In a sixth step, the transparent electrode layer of said second substrate layer is etched to provide a patterned electrode layer including an electrode element substantially identical to and spatially corresponding with the symbol pad. In a seventh step, the substrates are combined to form a display cell with the coated surfaces of the two cells aligned in opposing directions and having a small separation. In an eight step, said display cell is filled with a PDLC mixture. In the final step, the cell face formed by the first substrate is illuminated by crossed UV laser beams, and simultaneously illuminating the cell face formed by the second substrate by an incoherent UV source.
Abstract:
A compact high quality and lightweight symbol generator for projecting symbolic information into the field of view of a viewfinder is provided. The symbol generator comprises at least one ESBG device sandwiched between a pair of transparent plates which together function as a total internal reflection lightguide, switching electrodes and means for coupling illumination into the lightguide. Each ESBG device contains information encoded in a multiplicity of separately switchable grating regions. A plurality of independently switchable transparent electrodes elements, substantially overlay the separately switchable grating regions. When no electric field is applied, the ESBG device is in its diffracting state and projects images of said information towards the viewer. The projected images are surimposed onto an image of the external scene. When an electric field is applied the ESBG no longer diffracts and hence3 no information is displayed. In a further embodiment of the invention, the symbol generator could be configured to provide symbols of different colors by arranging for different symbols to contain ESBGs optimized for the required wavelengths and LEDs of appropriate spectral output. In a yet further embodiment of the basic invention several ESBG panels could be stacked such that by selectively switching different layers it is possible to present a range of different symbols of differing colors at any specified location in the field of view.
Abstract:
There is provided a method of fabricating an improved HPDLC transparent symbolic data display for projecting symbology into the field of view of a viewing device in which the HPDLC is localized to the display regions covered by the symbols. In a first step, a substrate to which an anti reflection coating and a transparent electrode layer have been applied is provided. In a second step, portions of said transparent electrode layer are removed to provide a patterned electrode layer including a symbol pad. In a third step, a layer of UV absorbing dielectric material is deposited over said patterned electrode layer. In a fourth step, the portion of said UV absorbing dielectric material overlapping said symbol pad is removed. In a fifth step, a second substrate to which an anti reflection coating and a transparent electrode layer have been applied is provided. In a sixth step, the transparent electrode layer of said second substrate layer is etched to provide a patterned electrode layer including an electrode element substantially identical to and spatially corresponding with the symbol pad. In a seventh step, the substrates are combined to form a display cell with the coated surfaces of the two cells aligned in opposing directions and having a small separation. In an eight step, said display cell is filled with a PDLC mixture. In the final step, the cell face formed by the first substrate is illuminated by crossed UV laser beams, and simultaneously illuminating the cell face formed by the second substrate by an incoherent UV source.
Abstract:
An optical add-drop mutiplexer device with low polarization dependent loss and polarization mode dispersion for use in optical communications systems comprises: a through optical waveguide, a' coupling circuit element and an add/drop circuit element comprising at least one of an input waveguide and an output waveguide. The coupling lightwave circuit element is optically coupled to the add/drop circuit element and the through optical waveguide by means of electrically variable gratings. Typically, the optical signal is a multi-channel WDM signal. Preferably, the variable grating is an electrically switchable Bragg grating. Each grating is overlaid by an electrode arrangement applied to a cover glass. Each electrode arrangement has first and second portions spaced from one another in the direction of light propagation. The electrodes provide electric fields that are generally orthogonal to one another and transverse to the direction of light propagation, thereby minimizing the effects of PDL and PMD.
Abstract:
A polarization device for implementing polarization diversity schemes in planar waveguide optical circuits is provided. A Polarization Beam Splitter (PBS) assembly comprises two birefringent wedges and a focusing lens. Advantageously, the birefringent wedges form a modified Wollaston prism. The PBS assembly divides a collimated input beam from the fiber collimator into vertically polarized and horizontally polarized collimated beams directed at slightly different angles. The focusing lens focuses the vertically polarized and horizontally polarized beams into two distinct spots located in substantially the same focal plane. The two focused spots are then coupled directly into the ends of two optical waveguides to propagate the two polarization states within a planar waveguide circuit. In a further embodiment of the invention, a Polarizing Beam Combiner device comprising a collimating lens and two birefringent wedges is provided. Advantageously, the birefringent wedges form a modified Wollaston prism. The collimating lens collimates light from a first source point having a first polarization and a second source point having a second polarization, the source points lying within the focal plane of the collimating lens. The source points are provided at the output face of a planar polarization diversity lightwave circuit where the output face coincides with the focal plane of the collimation lens. The birefringent wedges then combine the two orthogonally polarized collimated beams into an output collimated beam. In a yet further embodiment of the invention the PBS and PBC assemblies described above are combined in two channel polarization diversity waveguide device.