Colour cross-fading system for a luminaire
First Claim
1. A color cross-fading system for a luminaire which comprises first and second filter elements each comprising a substrate having thereon a plurality of layers of materials having different refractive indices, thickness of such layers varying continuously along a gradient axis of each filter element,said first filter element having a predominantly long wave pass characteristic such that at each point along said gradient axis visible light waves with wavelengths longer than a first cut-off wavelength are passed, said first cut-off wavelength proportional to said thickness of layers, which varies continuously along said gradient axis,said second filter element having a predominantly short wave pass characteristic such that at each point along said gradient axis visible light waves with wavelengths shorter than a second cut-off wavelength are passed, said second cut-off wavelength proportional to said thickness of layers, which varies continuously along said gradient axis, andmeans for mounting said first and second filter elements for movement independently of one another relative to an optical axis, whereby any point on the gradient axis of each filter element can be independently brought into alignment with the optical axis.
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Abstract
A color cross-fading system for a luminaire includes two filter disks or strips each provided with a multi-layer filter coating to provide a dichroic filter effect. In each case the thickness of the coating layers varies continuous along a gradient axis of the filter disk or strips. One disk acts predominantly as a long wave pass filter and the other act predominantly as a short wave pass filter, but each disk has an essentially "complex" characteristic enabling a very wide range of different colors to be obtained by cumulative subtractive filtering, by varying the positions of the two disks or strips relative to an optical axis.
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Citations
29 Claims
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1. A color cross-fading system for a luminaire which comprises first and second filter elements each comprising a substrate having thereon a plurality of layers of materials having different refractive indices, thickness of such layers varying continuously along a gradient axis of each filter element,
said first filter element having a predominantly long wave pass characteristic such that at each point along said gradient axis visible light waves with wavelengths longer than a first cut-off wavelength are passed, said first cut-off wavelength proportional to said thickness of layers, which varies continuously along said gradient axis, said second filter element having a predominantly short wave pass characteristic such that at each point along said gradient axis visible light waves with wavelengths shorter than a second cut-off wavelength are passed, said second cut-off wavelength proportional to said thickness of layers, which varies continuously along said gradient axis, and means for mounting said first and second filter elements for movement independently of one another relative to an optical axis, whereby any point on the gradient axis of each filter element can be independently brought into alignment with the optical axis.
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21. A complex color producing system which changes spectral composition of a light beam, comprising:
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a first filter element formed of a plurality of layers of materials having different refractive indices and formed to have a long wave pass characteristic along a first predetermined axis thereof which varies continually along said first axis proportional to a total thickness of said layers of materials, and such that a long wave pass characteristic at a first point on said first axis is different than the long wave pass characteristic at a second point on said first axis, said first filter element being positioned in an optical path of said light beam and movable within said optical path to allow a desired long wave pass characteristic; and a second filter element, optically in series with said first filter element, and having a short wave pass characteristic along a predetermined second axis thereof which varies continually along said second axis, proportional to a total thickness of said layers of materials, and such that a short wave pass characteristic at a first point on said second axis is different than the short wave pass characteristic at a second point on said second axis, said first filter element being positioned in the optical path of said light beam and movable within said optical path to allow a desired short wave pass characteristic; whereby light of a desired color can be obtained by selectively moving said first and second filter elements to different points along said first and second predetermined axis. - View Dependent Claims (22, 23, 24, 25, 28, 29)
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26. A method of providing a complex color from an input light beam comprising the steps of:
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providing a first filter element with a varying thickness and having a long wave pass, characteristic which varies along a first predetermined axis thereof proportional to said thickness in a way such that its characteristic at any one point along the first predetermined axis is different than a characteristic at any other point along the first predetermined axis; providing a second filter element with a varying thickness, optically in series with said first filter element, and having a short wave pass characteristic which varies along a second predetermined axis thereof proportional to said thickness in a way such that its characteristic at any one point along the second predetermined axis is different than a characteristic at any other point along the second predetermined axis; projecting a beam of multi-spectrum light along an optical axis; positioning said first and second filter elements such that a first selected portion of said first predetermined axis is along said optical axis and a second selected portion of said second predetermined axis is along said optical axis; and adjusting positions of said first and second filter elements to obtain a desired output color.
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Specification