Bae Systems, Inc.

Mark Edgar Bray

Jason John Lepley

Andrew James Williams

Methods and apparatus for detecting a modulating element of an object in a scene are described in which an element in a scene is illuminated with a modulated light source. A signal is obtained from an optical detector based on light received from the illuminated element. An intermediate frequency signal is detected from the signal obtained from the optical detector, the intermediate frequency signal being related to a frequency of the modulated light source and a frequency of modulation of the element within the scene. The modulating element is detected based on the intermediate frequency signal.

Active modulating element detection

A network, or part thereof for example a link,is described. The networkis for data communication through a medium, preferably wherein the medium comprises and/or is, at least in part, a liquid medium LM. The networkcomprises a set of transmitters, including a first transmitterA comprising a controllerA, wherein the first transmitterA is configured to transmit a set of polarised optical signals S, including a first polarised optical signal Scomprising first data Dof set of data D. The networkcomprises a set of receivers, including a first receiverA comprising a controllerA, wherein the first receiverA is configured to receive the first polarised optical signal S

Network and method for optical communication with polarised light signal

Methods and apparatus for detecting a modulating element of an object are described in which signal values are obtained from one or more optical detectors. A determination is made if there is a time dependent variation in the obtained signal values at the one or more optical detector and a modulating element is detected based on the determination.

Detection of modulating elements

An optical devicecomprises an objective lensdefining a focal plane FP and an eyepiecespaced apart therefrom, defining an optical axis OA therethrough. The optical devicecomprises an optical memberhaving a first planar face, arranged on the optical axis OA proximal the focal plane FP, wherein the first planar faceis arranged to oppose the objective lens. The optical devicecomprises a filter assemblycomprising a first notch filterarranged to attenuate transmission of electromagnetic radiation having a first wavelength λ, wherein the first notch filteris arranged in front of the optical member. The first notch filteris arranged at a first oblique angle θto the optical axis OA whereby, in use, incident electromagnetic radiation having a predetermined wavelength λpropagating along the optical axis is reflected by the first notch filteraway therefrom, wherein the first wavelength λand the predetermined wavelength λare different. In this way, retro-reflection of the incident electromagnetic radiation towards a source thereof is reduced, thereby better detection of the optical device

Optical device

A vehicle surface includes a set of retroreflectors configured to reflect, at least in part, incident hostile light towards a source of the incident hostile light.

Vehicle surface

An optical filter includes a first layer including a first notch filter arranged to attenuate electromagnetic radiation having a first wavelength &#x3bb;incident normally thereupon. The optical filter includes a second layer including a second notch filter arranged to attenuate electromagnetic radiation having a second wavelength &#x3bb;incident normally thereupon. The first wavelength &#x3bb;and the second wavelength &#x3bb;are different. The second layer is stacked upon the first layer. In use, the first notch filter attenuates the electromagnetic radiation having a predetermined wavelength &#x3bb; incident thereupon at a first angle of incidence &#x3b8;and the second notch filter attenuates the electromagnetic radiation having the predetermined wavelength &#x3bb; incident thereupon at a second angle of incidence &#x3b8;, wherein the first angle of incidence &#x3b8;and the second angle of incidence &#x3b8;are different.

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Chelmsford, United Kingdom

Mark Edgar Bray