A display panel comprising a body of optical material, the body having at least one optical image recorded therein in an encoded manner, wherein the image is selectively reconstructable and viewable by illuminating the panel using at least one light source only under predefined illumination conditions,
- wherein the encoded recording of the at least one image and the predefined illumination conditions only under which the image is selectively reconstructable and viewable are by virtue of the image is selectively reconstructable and viewable such that at least one first optical property or parameter of the reconstructed image being selectable in value from amongst variable values of the at least one first optical property or parameter, or whose value is actively modifiable over time, as a function of or in dependence on the value of at least one second optical property or parameter of the illumination conditions of the at least one light source which is selectable from amongst variable values thereof or which is actively modifiable in value over time;
- wherein the first optical property or parameter of the or each reconstructable image is selectable from optical properties or parameters of the or each image when reconstructed being any of the following (either singly or in any combination of two or more);
- (a)(i) a geometry, or visual shape or configuration, or other appearance, of the or each image;
- (a)(ii) in a case of plural images, a geometry, or visual shape or configuration, or other appearance, of the plural images when reconstructed and viewed collectively;
- (a)(iii) a position of the or each image in space;
- (a)(iv) a position in space (optionally the position of one or more focal/image planes) at which the or each image is reconstructable and/or is viewable;
- (a)(v) in a case of plural images, a relative spatial separation or displacement, relative to one another, of the plural images, optionally whether appearing in different spaced-apart planes or other locations in space;
- (a)(vi) a colour of (i.e., the wavelength or frequency of the light that forms) the or each image;
- (a)(vii) a polarisation (e.g., directional or phase) of light that forms the or each image;
- (a)(viii) a temporal dynamic nature or appearance or configuration of the or each image, optionally whether it is substantially static or whether the, or at least one of plural, image(s) changes with, or is animated over a period of, time;
- and
- wherein the second optical property or parameter of the illumination conditions of, or provided or generated by, the at least one light source, which is selectable from amongst variable values thereof or which is actively modifiable in value over time, is selectable from optical properties or parameters of the at least one light source being any of the following (either singly or in any combination of two or more):
- (b)(i) a position of the at least one, or each, light source, optionally its position relative to, or its spacing from, the display panel;
- (b)(ii) in the case of plural light sources, relative positions in space of the plural light sources, relative to each other and/or relative to the display panel, optionally the relative positions (with respect to each other and/or to the display panel) of plural such light sources either within a given plane in space or as between different planes in space that are spaced apart from one another;
- (b)(iii) an angle of incidence of one or more rays (or waves) of light emanating from the or each light source on the display panel as it/they interact(s) therewith;
- (b)(iv) a colour of the or each light source, i.e., the wavelength or frequency of the light that emanates from each light source and illuminates the display panel;
- (b)(v) a brightness or optical intensity of the light that emanates from the or each light source;
- (b)(vi) a polarisation (e.g., directional or phase) of the light that emanates from the or each light source;
- (b)(vii) a direction in space (optionally the direction relative to the display panel) of light rays that emanate from the or each light source, which direction is either substantially fixed and non-variable as a function of time, or varies as a function of time (optionally of the nature of directional scanning by the or each light source);
- (b)(viii) in the case of plural light sources, relative respective directions and relative respective angles of incidence and/or brightnesses/optical intensities and/or colours and/or polarisations of light rays that emanate from respective ones of the plurality of light sources, optionally in terms of the degree and/or speed by which such optical properties/parameters vary quantitatively or qualitatively as between different ones of the light sources as a collective array, series or group thereof (optionally the degree and/or speed by which a scanning operation is effected, as shared collectively between different ones of the plural light sources);
- and
- further wherein one or more of the second optical property(ies) or parameter(s) of the illumination conditions of (or provided or generated by) the one or more light sources is selectively adoptable, controllable or variable such that it/they dictate(s), govern(s) or lead(s) to a corresponding adoption or control of, or variation in or other functional relationship with, or dependence on, one or more respective one(s) of the one or more first optical property(ies) or parameter(s) of the or each optical image when reconstructed from the encoded record thereof in the display panel.