Apparatus for examining properties of objects
First Claim
1. An apparatus for examining magnetic properties of objects such as sheet material, including bank notes (20), comprisinga magneto-optic layer having optical properties influenceable by the magnetic properties of an object to be examined, a light source arranged to produce light that is coupled into the magneto-optic layer, and a detector arranged to detect light that is transmitted and/or reflected by the magneto-optic layer, wherein the magneto-optic layer comprises iron garnets, whereby iron garnets are formed by compounds based on iron garnet (RE3Fe5O12), where RE3 comprises three rare earth metal elements, and wherein iron (Fe) and/or oxygen (O) can be substituted at least partly by one or more other elements in each case, the magneto-optic layer is applied to a substrate comprises gallium garnets, wherein gallium garnets are formed by compounds based on gallium garnet (RE3Ga5O12), where RE3 comprises three rare earth metal elements, and gallium (Ga) and/or oxygen (O) can be substituted at least partly by one or more other elements in each case, and wherein oxygen (O) is substituted at least partly by sulfur (S) in the substrate.
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Accused Products
Abstract
The invention relates to apparatus for examining magnetic properties of objects, in particular sheet material, such as bank notes (20). The apparatus comprises a magneto-optic layer (10) whose optical properties are influenceable by the magnetic properties of the sheet material (20), a light source (11) for producing light that is coupled into the magneto-optic layer (10), and a detector (13) for detecting light that is transmitted and/or reflected by the magneto-optic layer (10). For reliable examination of the magnetic properties of sheet material it is provided that the direction of propagation of the coupled-in light extends parallel to a base surface (9) of the magneto-optic layer (10). The invention permits the magnetic properties in particular of sheet material with areas emitting very weak magnetic fields to be examined with very high sensitivity and reliability.
8 Citations
11 Claims
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1. An apparatus for examining magnetic properties of objects such as sheet material, including bank notes (20), comprising
a magneto-optic layer having optical properties influenceable by the magnetic properties of an object to be examined, a light source arranged to produce light that is coupled into the magneto-optic layer, and a detector arranged to detect light that is transmitted and/or reflected by the magneto-optic layer, wherein the magneto-optic layer comprises iron garnets, whereby iron garnets are formed by compounds based on iron garnet (RE3Fe5O12), where RE3 comprises three rare earth metal elements, and wherein iron (Fe) and/or oxygen (O) can be substituted at least partly by one or more other elements in each case, the magneto-optic layer is applied to a substrate comprises gallium garnets, wherein gallium garnets are formed by compounds based on gallium garnet (RE3Ga5O12), where RE3 comprises three rare earth metal elements, and gallium (Ga) and/or oxygen (O) can be substituted at least partly by one or more other elements in each case, and wherein oxygen (O) is substituted at least partly by sulfur (S) in the substrate.
Specification