Detection of vibrational energy via optical interference patterns
AssigneeThe United States of America as represented by the Secretary of the Navy
InventorsBradford A. Wheeler, Antonio L. Deus
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Abstract
A method and apparatus for sensing and measuring vibrational energy in a structure subject to vibrations is described. The method comprises the steps of applying a thin transparent film material having a thickness to a structure subject to vibrations and measuring the vibrational energy within the structure by measuring changes in the thickness of the thin transparent film material resulting from vibrations within the structure being transmitted to the thin transparent film material. The apparatus for sensing and measuring the vibrational energy comprises a light source for generating a coherent light beam, the thin transparent film material, and a detector for receiving reflected light rays from the top and bottom surfaces of the film material.
Claims28
A method for sensing and measuring vibrational energy in a structure comprising the steps of:
- applying a thin transparent film material having a thickness to a structure subject to vibrations;
- and
- measuring said vibrational energy within said structure by optically measuring changes in the thickness of said thin transparent film material resulting from vibrations within said structure transmitted to said thin transparent film material.
A method for sensing and measuring vibrational energy in a structure comprising the steps of:
- applying a thin transparent film material having a thickness to a structure subject to vibrations;
- measuring said vibrational energy within said structure by measuring changes in the thickness of said thin transparent film material resulting from vibrations within said structure transmitted to said thin transparent film material;
- illuminating surfaces of said thin film material with a light beam;
- and
- monitoring changes in a resulting fringe pattern in said thin film material caused by said changes in the thickness of said thin transparent film material to obtain data about said vibrational energy.
A method for sensing and measuring vibrational energy in a structure comprising the steps of:
- applying a thin transparent film material having a thickness to a structure subject to vibrations;
- measuring said vibrational energy within said structure by measuring changes in the thickness of said thin transparent film material resulting from vibrations within said structure transmitted to said thin transparent film material;
- providing at least one optical fiber for detecting said changes in thickness of said thin transparent film material,
- said measuring step further including illuminating surfaces of said thin film material with a light beam;
- and
- providing at least one lens to focus light reflected by said surfaces onto said at least one optical fiber.
An apparatus for sensing and measuring vibrational energy in a structure which comprises:
- a thin transparent film material having a thickness coupled to a structure subject to vibrations;
- and
- means for optically measuring the vibrational energy within said structure by measuring changes in the thickness of said thin transparent film material resulting from vibrations within said structure transmitted to said thin transparent film material.
An apparatus for sensing and measuring vibrational energy in a structure which comprises:
- a thin transparent film material having a thickness coupled to a structure subject to vibrations;
- means for measuring the vibrational energy within said structure by measuring changes in the thickness of said thin transparent film material resulting from vibrations within said structure transmitted to said thin transparent film material;
- means for illuminating surfaces of said thin transparent film material;
- and
- means for monitoring changes in a resulting fringe pattern in said thin film material caused by said changes in the thickness of said thin transparent film material to obtain data about said vibrational energy;
- means for monitoring changes in the thickness of said thin transparent film material by measuring the phase differences between a first beam reflected by a first one of said surfaces and a second beam reflected by a second one of said surfaces caused by said thickness changes.
An apparatus for sensing and measuring vibrational energy in a structure which comprises:
- a thin transparent film material having a thickness coupled to a structure subject to vibrations;
- means for measuring the vibrational energy within said structure by measuring changes in the thickness of said thin transparent film material resulting from vibrations within said structure transmitted to said thin transparent film material;
- said means for measuring vibrational including at least one optical fiber for detecting said changes in said thickness of said transparent film material;
- and
- said means for measuring vibrational energy further comprising means for illuminating surfaces of said thin film material with a light beam and at least one lens for focussing light reflected by said surfaces onto said at least one optical fiber;
- a layer of stiff epoxy material adjacent said metallic reflector for coupling said thin transparent film material to said vibrating structure.
A detector for use in an apparatus optically measuring vibrational energy in a structure subject to vibrations, said detector comprising:
- a thin film of oil contained within a transparent plastic containment pouch, said pouch having top and bottom surfaces.
A detector for use in an apparatus optically measuring vibrational energy in a structure subject to vibrations, said detector comprising a thin film dielectric material having top and bottom surfaces which are reflective, said dielectric material being transparent so as to allow light to pass through said dielectric material and reflect off said bottom surface, and said dielectric material having at least one of said surfaces in contact with said structure so that vibrations in said structure are transmitted to said dielectric material.
Dependencies are inferred from the claim text.