Abstract: A system for laser marking a substrate includes a multi-emitter array (16) for directing radiation onto a substrate. The multi-emitter array has a radiation guide (19) defining a number of discrete emission channels (20) with emitting ends (20a) of the emission channels (20) arranged in an array. Each emission channel (20) is coupled at its opposing end with two or more laser diodes (18a, 18b). The laser diodes (18a, 18b) are operated at a maximum operational output power (Pop) sufficiently below their rated maximum power (Pm) to provide acceptable levels of reliability whilst providing a combined radiation (24) emitted from each channel (20) having a power high enough to achieve increased operational speeds. The multi-emitter array (19) may comprise a number of optical fibres (26) whose emitter ends are arranged in an array. The system is particularly suited for inkless printing on substrates susceptible to colour change when irradiated.

Abstract: A laser marking system (10) comprises a marking controller (11) operable to control a plurality of laser diodes (13) to emit light through optical fibre (14) such that the emitting, ends of the optical fibres (14) form a multi-emitter array. Light emitted from the emitting ends of the optical fibres (14) is focussed by a lensing arrangement (15) on a substrate (16). The lensing arrangement (15) is substantially telecentric such that the non-telecentric angle, ?t, of the telecentric lens assembly satisfies (Formula I) where ?1/2 is the half angle divergence of the emitter beam and 1/F is the fraction of the emitter spot diameter do that corresponds to the maximum acceptable displacement in the image plane.

Abstract: The present invention relates to a method of marking a substrate that comprises a color forming material, comprising the steps of: activating a region of the substrate so as to transform it from an inactive, low reactive state to an active, high reactive state; irradiating a part of the activated region with an initial color changing radiation to effect an initial color change to a first color; and irradiating a part of the substrate that has been changed to the first color with a high power density beam of visible electromagnetic radiation to effect a further color change of the irradiated region to a second color.

Abstract: The present invention relates to a method of marking a substrate that comprises a color forming material, comprising the steps of: activating a region of the substrate so as to transform it from an inactive, low reactive state to an active, high reactive state; irradiating a part of the activated region with an initial color changing radiation to effect an initial color change to a first color; and irradiating a part of the substrate that has been changed to the first color with a high power density beam of visible electromagnetic radiation to effect a further color change of the irradiated region to a second color.

Abstract: A substrate marking apparatus for use in combination with a substrate comprising a multi-colour change diacetylene compound is disclosed. The substrate marking apparatus comprises: at least two radiation sources operable to emit radiation of different wavelengths, optical transformation elements and a control system. The control system takes digital file information and converts this to a set of emission instructions for the radiation sources. The radiation sources are then applied to the substrate in sequence and intensity determined by the control system such that the substrate is activated to change from a colourless state to any one of a range of multiple permanent colours.