Portable reflectometer and method for characterising the mirrors of solar thermal power plants
First Claim
1. A portable reflectometer for the spectral measurement of the specular reflection of mirrors of solar collectors, the portable reflectometer comprising:
- a module that carries out the measurement of the coefficient of the reflection of the mirror with at least a plurality of light emitting diodes as optical sources and a plurality of reflection photodetectors, one reflection photodetector respectively for each of the plurality of light emitting diodes;
a respective diaphragm for each of the plurality of light emitting diodes, each respective diaphragm having a diameter and a length larger than an aperture of the diaphragm, wherein each diaphragm limits, in size and aperture, the output light beam of the respective light emitting diode that is incident on the mirror, to ensure the size of the area illuminated on the mirror surface, thus limiting the contribution of diffuse reflection in the measurement, and wherein each of the plurality of reflection photodetectors is positioned to receive the respective output light beam after the output light beam has specularly reflected from the mirror;
an electronic system for acquiring and processing signals comprising a synchronous, analogical or digital detection, an analog-to-digital converter, an electronic modulation generator or a microprocessor configured to modulate the emission of light by each of the plurality of light emitting diodes to a respective measurement frequency, and a digital or analog electronic filter that filters the signals received from the respective reflection photodetectors to filter out frequency components except for the respective measurement frequency, the electronic system obtaining values for the reflectance of the mirror at specific light wavelengths;
a data processing and equipment control system that provides global reflectance values by weighting the obtained values with weights according to their respective wavelengths in the solar spectrum;
a system for storing relevant data;
a user interface system;
a system for the communication between the above systems; and
an exterior casing.
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Accused Products
Abstract
The invention relates to a portable reflectometer and to a method for characterizing the collector mirrors used in solar power plants for the in-field characterization of reflection coefficients. The equipment includes all of the components required for this measurement, such as a module to measure the reflection coefficient of the mirror, an electronic data acquisition and processing system, a system for processing data and controlling the equipment, a system for storing the data of interest, a user interface system, and a system allowing communication between the aforementioned systems and an outer casing. The equipment can be used to characterize the specular reflection coefficient of flat or curved mirrors of different thicknesses, without requiring adjustments to be made to the equipment, minimizing the influence of diffuse reflection on the measurement.
55 Citations
26 Claims
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1. A portable reflectometer for the spectral measurement of the specular reflection of mirrors of solar collectors, the portable reflectometer comprising:
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a module that carries out the measurement of the coefficient of the reflection of the mirror with at least a plurality of light emitting diodes as optical sources and a plurality of reflection photodetectors, one reflection photodetector respectively for each of the plurality of light emitting diodes; a respective diaphragm for each of the plurality of light emitting diodes, each respective diaphragm having a diameter and a length larger than an aperture of the diaphragm, wherein each diaphragm limits, in size and aperture, the output light beam of the respective light emitting diode that is incident on the mirror, to ensure the size of the area illuminated on the mirror surface, thus limiting the contribution of diffuse reflection in the measurement, and wherein each of the plurality of reflection photodetectors is positioned to receive the respective output light beam after the output light beam has specularly reflected from the mirror; an electronic system for acquiring and processing signals comprising a synchronous, analogical or digital detection, an analog-to-digital converter, an electronic modulation generator or a microprocessor configured to modulate the emission of light by each of the plurality of light emitting diodes to a respective measurement frequency, and a digital or analog electronic filter that filters the signals received from the respective reflection photodetectors to filter out frequency components except for the respective measurement frequency, the electronic system obtaining values for the reflectance of the mirror at specific light wavelengths; a data processing and equipment control system that provides global reflectance values by weighting the obtained values with weights according to their respective wavelengths in the solar spectrum; a system for storing relevant data; a user interface system; a system for the communication between the above systems; and an exterior casing. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A portable reflectometer for measuring the spectral reflection of a mirror, the portable reflectometer comprising:
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a plurality of light emitting diodes emitting light at different respective wavelengths, each of the plurality of light emitting diodes being directed toward the mirror at a respective angle of incidence with the mirror; a modulator that modulates each of the plurality of light emitting diodes to emit light modulated at a respective measurement frequency; a plurality of diaphragms each having a diameter and a length larger than an aperture of the diaphragm, one diaphragm respectively for each of the light emitting diodes, wherein each plurality of diaphragms limits the size of the beam that reaches the mirror from the respective light emitting diode; a plurality of reflection photodetectors, one reflection photodetector respectively for each of the plurality of light emitting diodes, each of the plurality of reflection photodetectors positioned to receive light from the respective light emitting diode after the light has specularly reflected from the mirror, each of the plurality of reflection photodetectors producing an electronic signal indicative of the intensity of light falling on the respective reflection photodetector; a digital or analog electronic filter that filters out frequencies other than the measurement frequency from the signal produced by the particular one of the plurality of reflection photodetectors being measured at each moment; and an electronic system that receives the signals produced by the plurality of reflection photodetectors and determines a global reflectance value for the mirror from a weighted average of the signals from the photodetectors.
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24. A method of measuring the coefficient of reflection of a mirror for a solar thermal power plant, the method comprising:
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providing a measurement module that comprises a plurality of light emitting diodes configured to emit light at different respective wavelengths;
a plurality of diaphragms, one diaphragm respectively for each of the plurality of light emitting diodes, wherein each of the plurality of diaphragms is sized and positioned to limit the size of the beam produced by the respective light emitting diode;
a plurality of reflection photodetectors, one reflection photodetector respectively for each of the plurality of light emitting diodes, each of the plurality of reflection photodetectors positioned to receive light from the respective light emitting diode after the light has specularly reflected from the mirror;
a modulator configured to modulate the intensity of the light produced by each of the plurality of light emitting diodes; and
a digital or analog filter configured to filter out frequencies from signals produced by the plurality of reflection photodetectors;energizing each of the plurality of light emitting diodes to produce a respective beam from each of the plurality of light emitting diodes; limiting the size of each of the beams using the respective diaphragm having a diameter and a length larger than an aperture of the diaphragm; modulating the intensity of each respective beam at the respective measurement frequency by the modulator; passing each respective beam through the glass of a second face mirror to reflect from the second face of the mirror; receiving the respective beam by the respective reflection photodetector after the beam has reflected from the mirror; producing, by the respective reflection photodetector, a signal indicative of the intensity of light falling on the respective reflection photodetector; filtering, using the analog or digital electronic filter, the signal produced by each respective reflection photodetector to remove frequencies other than the respective measurement frequency; and obtaining a value of the reflection coefficient for each of the wavelengths based on the filtered signal amplitude. - View Dependent Claims (25, 26)
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Specification