US Government As Represented by the Secretary of the Army

Massachusetts Institute of Technology

Michael Ghebrebrhan

Marin Soljacic

John Dimitris Joannopoulos

Ivan Celanovic

Peter Bermel

Adrian Y X Yeng

Rafif E Hamam

Landa Hoke

Klavs F Jensen

Steven G Johnson

Eric Dean Wetzel

Peter H Fisher

Walker Chan

Robert Pilawa-Podgurski

Christopher Marton

Mohammad Araghchini

The disclosed subject matter relates to relate to fibers, textiles, fabrics, clothing and methods that are retroreflective including fibers having a hollow sheath that is filled with retroreflective particles.

Particle-filled retroreflective fiber

Disclosed is a retro-reflective threadincluding an internal section; a plurality of fibers, each fiber comprising a respective longitudinal axis and a respective surface and each fiber comprising a first material that is at least partially optically transmissive, and wherein said plurality of fibers are configured with their respective longitudinal axes substantially co-linearly aligned with one another and said plurality of fibers are interconnected in series around said internal section and wherein a first partof said respective surface of each of said plurality of fibers faces into said internal section; and a reflective materialprovided on said first part of said respective surface of each of said plurality of fibers.

Retro-reflective thread, method of manufacturing same and a textile

The present invention provides systems, articles, and methods for discriminating electromagnetic radiation based upon the angle of incidence of the electromagnetic radiation. In some cases, the materials and systems described herein can be capable of inhibiting reflection of electromagnetic radiation (e.g., the materials and systems can be capable of transmitting and/or absorbing electromagnetic radiation) within a given range of angles of incidence at a first incident surface, while substantially reflecting electromagnetic radiation outside the range of angles of incidence at a second incident surface (which can be the same as or different from the first incident surface). A photonic material comprising a plurality of periodically occurring separate domains can be used, in some cases, to selectively transmit and/or selectively absorb one portion of incoming electromagnetic radiation while reflecting another portion of incoming electromagnetic radiation, based upon the angle of incidence. In some embodiments, one domain of the photonic material can include an isotropic dielectric function, while another domain of the photonic material can include an anisotropic dielectric function. In some instances, one domain of the photonic material can include an isotropic magnetic permeability, while another domain of the photonic material can include an anisotropic magnetic permeability. In some embodiments, non-photonic materials (e.g., materials with relatively large scale features) can be used to selectively absorb incoming electromagnetic radiation based on angle of incidence.

Discriminating electromagnetic radiation based on angle of incidence

Inventive systems and methods for the generation of energy using thermophotovoltaic cells are described. Also described are systems and methods for selectively emitting electromagnetic radiation from an emitter for use in thermophotovoltaic energy generation systems. In at least some of the inventive energy generation systems and methods, a voltage applied to the thermophotovoltaic cell (e.g., to enhance the power produced by the cell) can be adjusted to enhance system performance. Certain embodiments of the systems and methods described herein can be used to generate energy relatively efficiently.

Thermophotovoltaic energy generation

Growing community of inventors

Cambridge, MA, United States of America

Michael Ghebrebrhan