Abstract: A free-space optical communications (FSO) terminal including a first arm having a combined transmit-receive system configured to produce a data beam, encoding data, for transmission to a target and receive a received data beam from the target, a second arm having a component configured to transmit a further transmitted beam or utilise a further received beam, a pointing unit configured to steer the data beam to the target or the received data beam received from the target, and an optical fibre including a single-mode portion configured to carry the transmitted data beam and received data beam and couple the first arm to the pointing unit, and a multi-mode portion configured to carry the further transmitted beam or the further received beam and couple the second arm to the pointing unit.

Abstract: A free space optical communications terminal (100) including an optical arrangement of a quarter-wave plate (105), a Faraday rotator (110), a polarisation splitter (115), a first arm (120) comprising a receiver (126) and a transmitter (128), and a second arm (130) comprising a component (132) configured to utilise a received beam. The optical arrangement apportions a circularly polarised beam between the first and second arm.

Abstract: A method comprising moving a vehicle between a plurality of parked aircraft; at each aircraft, receiving aircraft-to-ground data from the aircraft at the vehicle by free-space-optical communication and storing the aircraft-to-ground data at the vehicle; and transferring the stored aircraft-to-ground data from the vehicle, wherein stored aircraft-to-ground data from two or more of the aircraft accumulates at the vehicle before it is transferred from the vehicle. Also a vehicle used in such a method.

Abstract: An aircraft comprising an aircraft transceiver to transfer data to and from the aircraft by free-space-optical communication when parked. The aircraft transceiver comprises a transmitter to generate outgoing light carrying aircraft-to-ground data; a lens to collimate the outgoing light to generate a collimated beam; a beam steering device to transform the collimated beam to generate a steered beam; a control system to operate the beam steering device to adjust an angle of the steered beam; and a receiver to sense incoming light carrying ground-to-aircraft data. The receiver receives the incoming light via the beam steering device and the lens. Also a vehicle with a similar transceiver to transfer data to and from a parked aircraft by free-space-optical communication.

Abstract: A pointing unit (100) for use with a free space optical (FSO) communications terminal (105) including an optical arrangement (101) of one or more optically transmissive steering elements (101a, 101b). The steering elements (101a, 101b) are arranged in an optical path of an incident beam (107) entering the optical arrangement (100), and the orientation of at least one element (101a, 101b), and the refractive index of at least one element (101a, 101b), are controllable to steer a beam (107b) towards a target (110).

Abstract: A free space optical communications terminal (100) including an optical arrangement of a quarter-wave plate (105), a Faraday rotator (110), a polarisation splitter (115), a first arm (120) comprising a receiver (126) and a transmitter (128), and a second arm (130) comprising a component (132) configured to utilise a received beam. The optical arrangement apportions a circularly polarised beam between the first and second arm.

Abstract: A pointing unit (100) for use with a free space optical (FSO) communications terminal (105). The pointing unit (100) includes an optical arrangement of a first (101) and second (102) pair of rotatable steering elements (101a, 101b, 102a, 102b). The steering elements are controlled according to a control scheme (10) to steer a beam (107b) towards a target (110).

Abstract: A pointing unit (100) for use with a free space optical (FSO) communications terminal (105) that includes an optical arrangement (101) of one or more optically transmissive steering elements (101a, 101b). The steering elements (101a, 101b) are arranged in an optical path of an incident beam (107) entering the optical arrangement (100), and the orientation of at least one element (101a, 101b), and the refractive index of at least one element (101a, 101b), are controllable to steer a beam (107b) towards a target (110).

Abstract: A pointing unit (100) for use with a free space optical (FSO) communications terminal (105) including an optical arrangement (101) of one or more optically transmissive steering elements (101a, 101b). The steering elements (101a, 101b) are arranged in an optical path of an incident beam (107) entering the optical arrangement (100), and the orientation of at least one element (101a, 101b), and the refractive index of at least one element (101a, 101b), are controllable to steer a beam (107b) towards a target (110).

Abstract: A pointing unit 102 is for use with a free space optical communications terminal 100 including an optical source 104. The pointing unit 102 includes a first portion 106 having a mirrored surface 108, the first portion 106 being orientatable relative to an optical beam 110 produced by the optical source 104 and incident on the mirrored surface 108 in use to direct a reflection 112 of the optical beam 110 from the mirrored surface 108 towards a target 107. The first portion 106 further includes a directional radio frequency antenna 114.

Abstract: A free space optical receiver including a multi-mode transmission medium configured to receive a light beam comprising a plurality of modes, the light beam having been propagated through a free space path. The free space optical receiver also includes a mode separating means configured to separate the plurality of modes for transmission through a corresponding first plurality of transmission media as a corresponding plurality of single-mode light beams, and a combining means configured to combine two or more of the plurality of single-mode beams into a combined beam for transmission through a further transmission medium.

Abstract: A free space optical communications transmitter terminal including an optical source arranged to provide a first beam of light encoding information to be communicated; an optical source arranged to provide photons encoding bits of a key of a Quantum Key Distribution protocol; and an optics arrangement. The first beam and the photons are linearly polarised. The optics arrangement is configured to combine the first beam and the photons into a single, second, beam to be transmitted to a receiver terminal; and transform the linear polarisation of the first beam into one of left and right circular polarisation and transform the linear polarisation of the photons into the other of left and right circular polarisation. A receiver terminal receives the second beam, transforms the circular polarisations into orthogonal linear polarisations, and filters out the linear polarisation of the first beam to allow the photons to pass to a single photon detector.

Abstract: A free space optical communications transmitter terminal including an optical source arranged to provide a first beam of light encoding information to be communicated; an optical source arranged to provide photons encoding bits of a key of a Quantum Key Distribution protocol; and an optics arrangement. The first beam and the photons are linearly polarised. The optics arrangement is configured to combine the first beam and the photons into a single, second, beam to be transmitted to a receiver terminal; and transform the linear polarisation of the first beam into one of left and right circular polarisation and transform the linear polarisation of the photons into the other of left and right circular polarisation. A receiver terminal receives the second beam, transforms the circular polarisations into orthogonal linear polarisations, and filters out the linear polarisation of the first beam to allow the photons to pass to a single photon detector.

Abstract: A free space optical receiver including a multi-mode transmission medium configured to receive a light beam comprising a plurality of modes, the light beam having been propagated through a free space path. The free space optical receiver also includes a mode separating means configured to separate the plurality of modes for transmission through a corresponding first plurality of transmission media as a corresponding plurality of single-mode light beams, and a combining means configured to combine two or more of the plurality of single-mode beams into a combined beam for transmission through a further transmission medium.

Abstract: A pointing unit 102 is for use with a free space optical communications terminal 100 including an optical source 104. The pointing unit 102 includes a first portion 106 having a mirrored surface 108, the first portion 106 being orientatable relative to an optical beam 110 produced by the optical source 104 and incident on the mirrored surface 108 in use to direct a reflection 112 of the optical beam 110 from the mirrored surface 108 towards a target 107. The first portion 106 further includes a directional radio frequency antenna 114.

Abstract: A system and method for determining the neurological function of a patient by examining ocular responses.

Abstract: A system and method for determining the neurological function of a patient by examining ocular responses.

Abstract: A ophthalmic aberrometer uses a wavefront sensor aligned with an eye under examination through an optical path and a light source for introducing a light beam into the eye via the optical path, wherein the optical path has a reference through which the light beam passes before passing to an eye retina to form a reference spot on the retina, a focus dynamic range extender, and an astigmatism dynamic range extender positioned in the optical path between the reference and an eye under examination. The wavefront sensor is positioned to receive a wavefront reflected from the eye retina via the optical path.

Abstract: Apparatus for determining if a cornea (whether in vitro or in vivo) has been modified (either surgically or otherwise). The method includes the steps of: passing a beam of collimated light a (either coherent or incoherent) through the cornea to produce a distorted wavefront; determining the characteristics of the distorted wavefront; and analyzing the distorted wavefront for characteristics that identify the presence of a modification. The analysis of the distorted wavefront can be for the presence of higher order aberrations, or Gausian characteristics which are indicative of modifications.

Abstract: The or at least one surface of a reflective or transmissive radiation focussing element is provided with at least one phase or amplitude diffraction grating that is distorted substantially according to a quadratic function. The surface or the opposed surface may also be provided with an aperture. The element is useful in three dimensional imaging and wavefront sensing systems.