Abstract: A viewing device is configured to magnify and view a marking on a gemstone. The viewing device includes a light source, a mask, a magnifying optical device, and a camera. The light source generates light directed along a first path towards the gemstone. The mask partially obscures the light from the light source to generate a pattern. The partially obscured light is reflected off of the gemstone and magnified by the magnifying optical device. The camera is positioned to capture the magnified light. One or more additional light sources generate light directed along a second path towards the gemstone. The light enters the gemstone through a preferred facet and internally reflects. Internally reflected light scatters off of an internal mark in the gemstone and exits the gemstone through the gemstone's top face. The reflected and scattered light is magnified by the magnifying optical device and captured by the camera.

Abstract: A liquid crystal device (400) is provided comprising: a liquid crystal layer having a thickness and comprising: a liquid crystal material; and a plurality of polymer structures (414a, 414b) comprising polymerised liquid crystal material. Each polymer structure (414a, 414b) is located at a different depth in the thickness of the liquid crystal layer. Electrodes are provided configured to apply an electric field to the liquid crystal layer. Each polymer structure (414a, 414b) has a different selected locked-in liquid crystal state.

Abstract: A viewing device is configured to magnify and view a marking on a gemstone. The viewing device includes a light source, a mask, a magnifying optical device, and a camera. The light source generates light directed along a first path towards the gemstone. The mask partially obscures the light from the light source to generate a pattern. The partially obscured light is reflected off of the gemstone and magnified by the magnifying optical device. The camera is positioned to capture the magnified light. One or more additional light sources generate light directed along a second path towards the gemstone. The light enters the gemstone through a preferred facet and internally reflects. Internally reflected light scatters off of an internal mark in the gemstone and exits the gemstone through the gemstone's top face. The reflected and scattered light is magnified by the magnifying optical device and captured by the camera.

Abstract: The invention provides a method for laser modification of a sample to form a modified region at a target location within the sample. The method comprises positioning a sample in a laser system for modification by a laser; measuring tilt of a surface of the sample through which the laser focusses; using at least the measured tilt to determine a correction to be applied to an active optical element of the laser system; applying the correction to the active optical element to modify wavefront properties of the laser to counteract an effect of coma on laser focus; and laser modifying the sample at the target location using the laser with the corrected wavefront properties to produce the modified region.

Abstract: The invention provides a method for laser modification of a sample to form a modified region at a target location within the sample. The method comprises positioning a sample in a laser system for modification by a laser; measuring tilt of a surface of the sample through which the laser focusses; using at least the measured tilt to determine a correction to be applied to an active optical element of the laser system; applying the correction to the active optical element to modify wavefront properties of the laser to counteract an effect of coma on laser focus; and laser modifying the sample at the target location using the laser with the corrected wavefront properties to produce the modified region.

Abstract: Method of laser modifying an optical fibre to form a modified region at a target location within the fibre, comprising positioning at least a portion of an optical fibre in a laser system for modification by a laser, applying a correction to an active optical element of the laser system to modify wavefront properties of the laser to counteract an effect of aberration on laser focus, and laser modifying the optical fibre at the target location using the laser with the corrected wavefront properties to produce the modified region.

Abstract: Method of laser modifying an optical fibre to form a modified region at a target location within the fibre, comprising positioning at least a portion of an optical fibre in a laser system for modification by a laser, applying a correction to an active optical element of the laser system to modify wavefront properties of the laser to counteract an effect of aberration on laser focus, and laser modifying the optical fibre at the target location using the laser with the corrected wavefront properties to produce the modified region.

Abstract: A device for modulation of light (16) having a wavelength, comprising: a first substrate (10) with a first face (81) and a second opposite face (82), and comprising a first electrode (11); a second substrate (20) adjacent to the second face (82) and defining a gap between the first and second substrate (10, 20), the second substrate (20) comprising a second electrode (21); a responsive liquid crystal layer (15) disposed in the gap, wherein the responsive liquid crystal layer (15) has a flexoelectro-optic chiral nematic phase, and is birefringent with an optic axis that tilts in response to an applied electric field between the first and second electrode (11, 21); and a mirror adjacent to the second substrate (20), the mirror configured to reflect incident circular polarised light while preserving its handedness.

Abstract: A method of fabricating one or more colour centres in a crystal is described. The method comprises focusing a laser into a crystal to induce the creation, modification, or diffusion of defects within a focal region of the laser. Fluorescence detection is used to determine when one or more colour centres are formed within the focal region and the laser is terminated when a desired number of colour centres have been formed. The method enables colour centres to be formed in a crystal with a high degree of control in terms of both the number and location of colour centres within the crystal, and a degree of control over other parameters such as colour centre orientation and local environment. In particular, it is possible to form a well-defined pattern of colour centres within a crystal.

Abstract: A laser system for modification of a sample to form a modified region at a target location within the sample, the target location being disposed below a surface of the sample, the laser system comprising: a laser light source configured to provide laser light; a sample holder for supporting the sample; one or more optical elements configured to direct the laser light from the laser light source into the sample when the sample is supported by the sample holder, wherein the one or more optical elements are configured to focus the laser light into the sample, and wherein the one or more optical elements includes a component configured to correct for spherical aberration caused by mismatch in refractive index at the surface of the sample through which the laser light enters the sample such that the laser light is focused at the target location within the sample, a tilt measurement device configured to measure a tilt angle of the surface of the sample relative to an optical axis of the laser light entering through

Abstract: A device for modulation of light (16) having a wavelength, comprising: a first substrate (10) with a first face (81) and a second opposite face (82), and comprising a first electrode (11); a second substrate (20) adjacent to the second face (82) and defining a gap between the first and second substrate (10, 20), the second substrate (20) comprising a second electrode (21); a responsive liquid crystal layer (15) disposed in the gap, wherein the responsive liquid crystal layer (15) has a flexoelectro-optic chiral nematic phase, and is birefringent with an optic axis that tilts in response to an applied electric field between the first and second electrode (11, 21); and a minor adjacent to the second substrate (20), the minor configured to reflect incident circular polarised light while preserving its handedness.

Abstract: A method is disclosed for authenticating a product. The method comprises: receiving a verification code associated with the product; applying an electric field to a liquid crystal device (100) located in or on the product, the liquid crystal device (100) comprising: a first substrate (105); a second substrate (110) spaced apart from the first substrate (105); a liquid crystal composition (115) located between the first substrate (105) and the second substrate (110); wherein the liquid crystal composition (115) comprises one or more regions (120) of polymerised liquid crystal composition; and a first electrode (125) and a second electrode (130) configured to apply the electric field; comparing a display output by the liquid crystal device (100) in response to the application of the electric field to the verification code associated with the product; wherein, if the display output by the liquid crystal device (100) matches the verification code associated with the product, the product is authenticated.

Abstract: A method of fabricating one or more colour centres in a crystal is described. The method comprises focusing a laser into a crystal to induce the creation, modification, or diffusion of defects within a focal region of the laser. Fluorescence detection is used to determine when one or more colour centres are formed within the focal region and the laser is terminated when a desired number of colour centres have been formed. The method enables colour centres to be formed in a crystal with a high degree of control in terms of both the number and location of colour centres within the crystal, and a degree of control over other parameters such as colour centre orientation and local environment. In particular, it is possible to form a well-defined pattern of colour centres within a crystal.

Abstract: There is provided a method of fabricating a trapped vacancy in a crystal lattice of a target comprising: positioning the target in a laser system, the target containing vacancy trapping elements within the crystal lattice; modifying the crystal lattice within the target by using a laser to generate a lattice vacancy; and annealing the target to cause the lattice vacancy to migrate and be captured by a vacancy trapping element to form the trapped vacancy in the crystal lattice.

Abstract: The invention provides a method for laser modification of a sample to form a modified region at a target location within the sample. The method comprises positioning a sample in a laser system for modification by a laser; measuring tilt of a surface of the sample through which the laser focusses; using at least the measured tilt to determine a correction to be applied to an active optical element of the laser system; applying the correction to the active optical element to modify wavefront properties of the laser to counteract an effect of coma on laser focus; and laser modifying the sample at the target location using the laser with the corrected wavefront properties to produce the modified region.

Abstract: Method of laser modifying an optical fibre to form a modified region at a target location within the fibre, comprising positioning at least a portion of an optical fibre in a laser system for modification by a laser, applying a correction to an active optical element of the laser system to modify wavefront properties of the laser to counteract an effect of aberration on laser focus, and laser modifying the optical fibre at the target location using the laser with the corrected wavefront properties to produce the modified region.

Abstract: There is provided a method of fabricating a trapped vacancy in a crystal lattice of a target comprising: positioning the target in a laser system, the target containing vacancy trapping elements within the crystal lattice; modifying the crystal lattice within the target by using a laser to generate a lattice vacancy; and annealing the target to cause the lattice vacancy to migrate and be captured by a vacancy trapping element to form the trapped vacancy in the crystal lattice.

Abstract: In a method and system for controlling the shape of an optical pulse, the two-dimensional shape of the phase front is controlled using a first control device and the shape of the phase front and the two-dimensional shape of the pulse front is controlled using a second control device. The combined effect on the phase front results in a desired overall phase front control and the second device provides the desired overall pulse front control. This enables the phase front control and pulse front control to be decoupled. Correcting for pulse lengthening of femtosecond laser pulses during focusing by a dispersive lens. The spatially varying phase (72) introduced by the lens can be corrected for by a spatial light modulator like (SLM) a liquid crystal modulator. The spatially varying arrival time at the focus (70) can be compensated for by a deformable mirror (DM). A controller with a feedback loop and pulse characterization in the focus can compensate for the errors introduced by any dispersive focusing means.