Imedge Technology, Inc.

Nashua Corporation

Nashua Photo Limited

Reflexite Corporation

Holtronic Technologies Plc

Other

Northern Telecom Limited

Durand Limited

Nahsua Photo Limited

Nicholas John Phillips

Zane Coleman

Michael H Metz

Carl Flatow

Robert B Nilsen

William Nevil Johnson

Robin Clabburn

Christopher Alan Barnett

William N Johnson

Lee A Batchelder

William Nevil Heaton Johnson

Terence Edward Yeo

Jonathan Michael Blackledge

Bruce Napier

Christopher A Barnett

Retroreflective prism sheeting is formed in a mold with textured facets and/or windows thereon. Smaller prisms are formed adjacent larger prisms. Optionally, the optical axis of the prisms may be tilted with respect to one another, preferably in a negative direction. The textured facets or windows provide more uniform retroreflected light intensity distribution and whiteness of the sheeting.

Textured retroreflective prism structures and molds for forming same

Anti-counterfeiting marking for documents, which marking may be disguised as an incidental or artistic feature of overall marking on the documents is adapted to be read by a complementary reading device. In one embodiment the marking may be a one, two or three-dimensional statistically fractal marking and is representative of an array of digits in which the value of each digit is represented by the fractal dimensions over a corresponding region or set of regions of the document bearing the marking. Corresponding apparatus for reading the anti-corresponding marking is also provided.

Anti-counterfeiting and diffusive screens

A light diffusing screen is made by exposing a photopolymerisable material to polymerising light through a mask having an array of light-transmitting apertures in an opaque background or vice versa, at least some of the light being directed obliquely onto the photopolymerisable material. The resulting photopolymerised material has asymmetric light diffusing properties. In some embodiments two beams of light directed onto the photopolymerisable material are equally and oppositely inclined to the perpendicular to the plane of the material. An analogous effect may be provided, in other embodiments, by exposing the photopolymerisable material to light converging conically on the photopolymerisable material.

Projection screens and the like

A method and system are disclosed for recording and displaying grazing-incidence (i.e., steep reference beam angle) holograms supported on a substrate having thin edge-illuminatable geometry. The system and process use thin edge-illuminated substrates that facilitate optimal coupling of the reference light beam at steep angles approaching grazing incidence, while maximizing the contrast of the slanted fringe structures thereof. Different recording techniques are employed when the index of refraction of the substrate is greater than that of the recording medium, than when the index of refraction of the substrate is less than that of the recording medium. A recording and playback system of complementary design is provided for recording slanted-fringe volume holograms under relaxed conditions, without compromising the light diffraction efficiency of the holograms under different playback conditions.

Grazing incidence holograms and system and method for producing the same

Holographic fingerprint device

A compact system for producing high contrast and high resolution images of a topographical surface associated with an object. The system utilizes a novel holographic optical element to produce images of topographical surfaces differentiating between ridges and valleys, and providing image details of artifacts. The system of the present invention can be realized in the form of a hand-held instrument for use in in vivo imaging of fingerprint, skin tissue and the like.

Topographical object detection system

A method and ultra-compact system has been developed for illuminating and detecting the surface topography of an object such as the finger of an individual. The system is capable of producing high-contrast images which can be electronically transmitted in real-time, or stored using electronic or photographic recording devices. Light traveling within a light transmitting substrate is redirected by a slanted-fringe light diffractive grating preferably embodied within a volume hologram. The volume hologram, either of the reflection or transmission type, is attached to the light transmitting substrate, and functions to diffract light striking thereupon and illuminate an object having topographical surface structure. After being spatially and intensity modulated in accordance with topographical details of the illuminated object, the modulated light passes back through the light transmitting substrate and the volume hologram, onto an image detection array, for subsequent analysis. Each of the disclosed embodiments has a compact geometry suitable for use in diverse object identification applications.

Device for forming and detecting fingerprint images with valley and

Screens having graded refractive index lenses

In the manufacture of a screen suitable for use as a rear projection screen, a first layer (10) of a photopolymerisable monomer or oligomer which is tacky in its monomeric or oligomeric form and non-tacky in its polymerised form, is exposed to polymerising light, such as ultra-violet light, in a pattern comprising an array of spots of such light, and consequent selective polymerisation is allowed to take place in the first layer (10). There is then applied to the exposed surface of the first layer (10) a printing medium comprising an opaque pigment layer (28) on a supporting substrate (30) so that the pigment layer (28) contacts the exposed surface of the first layer (10) and sticks to the unpolymerised and therefore still tacky regions of the first layer (10), but not to the polymerised regions. The substrate (30) carrying the pigment layer (28) is then stripped from the first layer (10), leaving pigment (28) adhering only to the unpolymerised regions. The adhering pigment (28) may form a contrast enhancing mask over the regions intermediate the exposed spots of photopolymer, which form microlenses.

Method of imparting contrast enhancement properties to diffusing,

A method and system for recording and displaying grazing-incidence (i.e., steep reference beam angle) holograms supported on a substrate having thin edge-illuminatable geometry. The system and process of the present invention uses thin edge-illuminated substrates that facilitate optimal coupling of the reference light beam at steep angles approaching grazing incidence, while maximizing the contrast of the slanted fringe structures thereof. A recording medium is in direct contact with a thin substrate whose refractive index is greater than the bulk refractive index of the recording medium. At the substrate interface, the recording medium has a gradient-type index matching region, created by exposure of the recording medium to reference beam illumination, prior to the further application of an object beam to create a fringe pattern.

A progressive method of writing a long grating in a substrate using a pulsed interference fringe pattern. The substrate is moved through the fringe pattern while being continuously illuminated with light of a different wavelength to produce a diffracted beam whose phase is monitored to produce a control signal that regulates the pulsing of the writing beam to ensure that the fringe pattern is present only when it is in correct registry with the grating being written.

Writing diffraction gratings with interference fringe patterns

A method and system for recording and displaying grazing-incidence (i.e., steep reference beam angle) holograms supported on a substrate having thin edge-illuminatable geometry. The system and process of the present invention uses thin edge-illuminated substrates that facilitate optimal coupling of the reference light beam at steep angles approaching grazing incidence. Different recording techniques are employed when the index of refraction of the substrate is greater than that of the recording medium, than when the index of refraction of the substrate is less than that of the recording medium.

Randomised mask for a diffusing screen

An image display arrangement comprising a collimating fibre-optic plate arranged to be illuminated from one side, for example a fibre optic plate forming the screen of a c.r.t. display tube and coated with a phosphor for providing such light, has, on at least one side thereof a layer of a photopolymer having formed therein an array of integral graded refractive index lenses, each extending over and in register with the end face, adjoining the photopolymer layer, of a respective optic fibre of the fibre optic plate. Each said graded refractive index lens is of a power such as to enhance the collimating effect of the respective optic fibre. A diffusion layer is preferably superimposed on the photopolymer layer, to impart a controlled diffusion to light passing through the optical fibres and said photopolymer layer, such as to render invisible or less visible the regions, in the fibre-optic plate, between adjoining optical fibres. The invention thus reduces or eliminates the so-called 'chicken wire' effect.

Growing community of inventors

Loughborough, United Kingdom

Nicholas John Phillips