Abstract: A diffraction surface and a method of making the surface. The surface may be applied to labels and other items to identify the origin of the goods to which the label is attached. The surface can include a block grating including ridges and recesses in the enclosed squares or rectangles. The diffraction grating is manufactured by processing a data stream indicative of the image, including obtaining a Fourier Transform of the data stream and preferably clipping and quantising the data stream, and deforming a plate surface in accordance with the data stream. Also claimed is a diffraction grating having spaced first and second portions each producing an image on a receiving surface in response to illumination by a reading light beam, configured such that when the reading light beam moves from the first to the second portion, a change occurs in the first image to produce the second image.

Abstract: A diffraction surface and a method of making the surface. The surface may be applied to labels and other items, to identify the original of the goods to which the label is attached. The surface can include a block grating. For example, the surface could include a plurality of blocks which adapted when illuminated will produce a recognisable image on an intercepting surface. The diffraction grating is manufactured by processing a data stream indicative of the image. Processing of the data stream includes obtaining a Fourier Transform of the data stream. Preferably, the data stream is clipped and quantised.

Abstract: A diffraction surface and a method of making the surface. The surface may be applied to labels and other items to identify the origin of the goods to which the label is attached. The surface can include a block grating including ridges and recesses in the enclosed squares or rectangles. The diffraction grating manufactured by processing a data stream indicative of the image including obtaining a Fourier Transform of the data stream and preferably clipping and quantising the data stream, and deforming a plate surface in accordance with the data stream. Also claimed is a diffraction grating having spaced first and second portions each producing an image on a receiving surface in response to illumination by a reading light beam, configured such that when the reading light beam moves from the first to the second portion, a change occurs in the first image to produce the second image.

Abstract: A diffraction surface and a method of making the surface. The surface may be applied to labels and other items, to identify the original of the goods to which the label is attached. The surface can include a block grating. For example, the surface could include a plurality of blocks which adapted when illuminated will produce a recognisable image on an intercepting surface. The diffraction grating is manufactured by processing a data stream indicative of the image. Processing of the data stream includes obtaining a Fourier Transform of the data stream. Preferably, the data stream is clipped and quantised.

Abstract: A viewing device to aid in authenticating an optical surface. The device includes a laser diode which produces a beam of light. The device includes a viewing screen which receives a diffracted image produced by the beam illuminating the surface. The device further includes a lens system which causes the diffracted beam to be focused on the viewing screen.