Abstract: A method includes simultaneously illuminating a material using multiple first radiances and measuring multiple second radiances from the material. Each second radiance includes at least a portion of two or more first radiances that have interacted with the material. The method also includes determining a structure of the material based on the measurements. The first radiances may be directed at the material from different directions, and the second radiances may be measured at different positions around the material. The structure of the material could be determined by determining at least one of a scattering profile and an absorption profile. If the material includes a sheet of paper, a boundary between two layers in the sheet of paper could be identified by a discontinuity in the scattering profile, and a non-uniform distribution of a filler in the sheet of paper could be identified by a smooth variation in the scattering profile.

Abstract: A method includes generating at least one first light beam and generating at least one second light beam and at least one third light beam using the at least one first light beam. The at least one first light beam has a plurality of first regions, the at least one second light beam has a plurality of second regions, and the at least one third light beam has a plurality of third regions. Each of the first, second, and third light beams has at least two regions that are spectrally different. The method also includes measuring a spectrum in each of a plurality of first wavelength bands for each of the second regions. The method further includes illuminating at least part of an object with the at least one third light beam to produce at least one fourth light beam. The at least one fourth light beam has a plurality of fourth regions, where at least two of the fourth regions are spectrally different.

Abstract: A method includes illuminating a material using first light. The first light is associated with one or more ultraviolet wavelengths/wavelength bands, and the material includes pulp fibers. The method also includes measuring second light from the material, where the second light is based on the first light. The method further includes determining an amount of lignin in the material using the measured second light. The ultraviolet wavelengths/wavelength bands could include at least one wavelength between 260 nanometers and 300 nanometers, inclusive (such as 280 nm). The one or more ultraviolet wavelengths/wavelength bands could additionally include 205 nanometers, 250 nanometers, 300 nanometers, and/or 360 nanometers. The method could also include illuminating the material using third light and measuring fourth light from the material, where the fourth light is based on the third light.

Abstract: A method includes illuminating a material with first light and capturing an image of second light transmitted through the material. The method also includes analyzing multiple regions of the image and determining one or more haze measurements associated with the material based on the analyzing. The method further includes storing and/or outputting the one or more haze measurements. Analyzing the multiple regions of the image may include summing pixel values in each region to produce a total pixel value for that region. The multiple regions of the image may include (i) a first region forming a first disc, (ii) a second region forming either a first annular region around the first region or a second disc larger than and including the first disc, and (iii) a third region forming either a second annular region around the second region or a third disc larger than and including the first and second discs.

Abstract: A method includes receiving multiple biased measurements associated with a property of a sheet of material, where the biased measurements correspond to multiple known sheet geometries. The method also includes determining an unbiased measurement associated with the property of the sheet using the biased measurements, where the unbiased measurement corresponds to a nominal sheet geometry. The method further includes storing and/or outputting the unbiased measurement. Determining the unbiased measurement could include performing regression using the biased measurements and their corresponding sheet geometries to identify an estimated value of the property of the sheet at the nominal sheet geometry. The biased measurements can be generated using one or more sensors, and the sheet may not be stabilized during the biased measurement generation. Additional sheet geometries can also be created, such as by varying a tilt angle, a curvature, and/or a position of the sheet.

Abstract: An image-based measurement technique that directly measures the orientation of fibers in a moving web that comprises nonwoven material measures the orientation angles of the individual fibers so that a more robust estimate of the statistical distribution of fibers is obtained. The technique includes the steps of: (a) illuminating an area on at least one side of the web with radiation; (b) obtaining at least one digital image of the illuminated area; and (c) calculating the fiber orientation of the web by processing the at least one digital image with a gradient operator thereby analyzing the distribution of observed fiber orientation angles within the image. The gradient operator is preferably of a non-integer order between ? and ? and particularly between ¼ and ¾. The use of fractional-gradient operators yields more reliable results than when integer order gradients are employed.

Abstract: Devices, systems, and methods for measuring the color of a sample are disclosed. The exemplary device may have one or more light emitting diodes for directing a beam of ultraviolet light onto the sample and may also have one or more light emitting diodes for directing a beam of visible light onto the sample. The exemplary device may have a component for controlling the timing and power of operation of each light emitting diode. The exemplary device may also have at least one light detector for receiving the beam of light reflected from or transmitted through the sample and measuring at least one wavelength band of the received light. The exemplary device may further have a measurement analyzer for determining the color of the sample based on the measured light. The color may be determined for a specified illuminator incorporating effects of fluorescence.

Abstract: A method includes illuminating a mixture of materials in a wet-end of a paper process, where the mixture includes an ultraviolet-activated material. The method also includes measuring light from the mixture and determining a property of the ultraviolet-activated material based on the measured light. The method may further include adjusting an operation in the wet-end of the paper process based on the determined property of the ultraviolet-activated material. The determined property could include a quantity of fluorescent material in recycled material used to form stock for a paper machine and/or a quantity of fluorescent material in stock provided to a headbox in the paper process. Adjusting the operation in the wet-end could include adjusting an amount of one or more materials used to form stock provided to the headbox, such as a fluorescent whitening agent, fixative, fluorescent fiber, fluorescent pigment, fluorescent particle, fluorescent highlight, fluorescent planchette, or fluorescent quencher.

Abstract: A system and method for color measurements or other spectral measurements of a material are provided. An illuminating device generates light for illuminating a sample of material. A detector detects light that has interacted with the sample and provides a measurement of the light that has interacted with the sample. A controller adjusts a duty cycle of the illuminating device to control the illumination of the sample. The measurement could be used by an analyzer to determine a spectral characteristic of the sample (such as a color of the sample). The determination of the spectral characteristic could be done without using any measurement of light that has not interacted with the sample. One or multiple light emitting diodes (LEDs) could be used to illuminate the sample, and the duty cycle of individual LEDs or groups of LEDs could be adjusted.

Abstract: A method includes receiving light from a material at a digital imaging device. The method also includes filtering the light into at least three spectral bands using a filter, where different regions of the filter pass different spectral bands. The method further includes measuring the light in each of the spectral bands and determining at least one color associated with the material using the measured light in the spectral bands. The different regions of the filter could include multiple masks (where each mask passes one of the spectral bands), different areas of a linear variable filter, and/or individual filters (where each individual filter passes one of the spectral bands). The digital imaging device could include a digital camera. The filter could be formed on a detector in the digital camera, and/or a component of the digital camera could be replaced with the filter.

Abstract: A method includes illuminating a material using first light. The first light is associated with one or more ultraviolet wavelengths/wavelength bands, and the material includes pulp fibers. The method also includes measuring second light from the material, where the second light is based on the first light. The method further includes determining an amount of lignin in the material using the measured second light. The ultraviolet wavelengths/wavelength bands could include at least one wavelength between 260 nanometers and 300 nanometers, inclusive (such as 280 nm). The one or more ultraviolet wavelengths/wavelength bands could additionally include 205 nanometers, 250 nanometers, 300 nanometers, and/or 360 nanometers. The method could also include illuminating the material using third light and measuring fourth light from the material, where the fourth light is based on the third light.

Abstract: A method includes receiving a sheet of material at a sensor assembly. The sensor assembly includes a sensor configured to measure a property of the sheet. The method also includes stabilizing the sheet with respect to the sensor using a guide roller. Stabilizing the sheet includes using the guide roller to remove at least a portion of a first boundary layer of air moving towards the guide roller and to reform at least a portion of a second boundary layer of air moving away from the guide roller. For example, the guide roller could include a plurality of grooves or openings in a surface of the guide roller, or the guide roller could include a plurality of rings spaced apart from one another. Air could move from one side of the guide roller to another side of the guide roller through the grooves, through the openings, or between the rings.

Abstract: A method includes illuminating a mixture of materials in a wet-end of a paper process, where the mixture includes an ultraviolet-activated material. The method also includes measuring light from the mixture and determining a property of the ultraviolet-activated material based on the measured light. The method may further include adjusting an operation in the wet-end of the paper process based on the determined property of the ultraviolet-activated material. The determined property could include a quantity of fluorescent material in recycled material used to form stock for a paper machine and/or a quantity of fluorescent material in stock provided to a headbox in the paper process. Adjusting the operation in the wet-end could include adjusting an amount of one or more materials used to form stock provided to the headbox, such as a fluorescent whitening agent, fixative, fluorescent fiber, fluorescent pigment, fluorescent particle, fluorescent highlight, fluorescent planchette, or fluorescent quencher.

Abstract: An image-based measurement technique that directly measures the crepe pattern on a moving sheet employs a suitable arrangement of illumination, optical elements, and an imaging device to obtain digital images of the sheet surface. The image resolution is sufficient to represent tissue crepe folds at the scale of the crepe. A spectral analysis of some or of all the images reveals the crepe folding pitch. Further analysis of the image optionally reveals other crepe structural parameters, such as the distribution of crepe fold orientation angles and distribution of linear fold lengths. Corrective actions can be implemented in response to changes in the crepe structure. The pitch of creping is the primary parameter for describing the crepe pattern; in addition, analyzing the images with a gradient operator can yield information regarding the orientation of the crepe folds and distribution of angles of the crepe furrows on the hood side or equivalently of the crepe seams on the cylinder side.

Abstract: In a papermaking system having a headbox to dispense a jet of liquid and paper forming fibers, an improvement comprising at least one sensor arrangement for simultaneously or sequentially measuring in at least one location the jet velocity or jet flow correlation of the jet at plural known angles relative to the machine direction. The measured data is analyzed to generate a velocity vector profile or velocity direction profile of the jet, and hence to determine the profile of fiber orientation angles laid down in the sheet formed of the jet.

Abstract: A method includes simultaneously illuminating a material using multiple first radiances and measuring multiple second radiances from the material. Each second radiance includes at least a portion of two or more first radiances that have interacted with the material. The method also includes determining a structure of the material based on the measurements. The first radiances may be directed at the material from different directions, and the second radiances may be measured at different positions around the material. The structure of the material could be determined by determining at least one of a scattering profile and an absorption profile. If the material includes a sheet of paper, a boundary between two layers in the sheet of paper could be identified by a discontinuity in the scattering profile, and a non-uniform distribution of a filler in the sheet of paper could be identified by a smooth variation in the scattering profile.

Abstract: A sheet of material is received at a sensor assembly, which includes a sensor operable to measure a property of the sheet. An air flow is generated that is substantially tangential to the sheet in order to at least partially control a position of the sheet relative to the sensor assembly. For example, the sheet may be associated with an upstream boundary layer of air and a downstream boundary layer of air. At least part of the air from the upstream boundary layer could be removed and used to provide an air flow forming at least part of the downstream boundary layer. Also, the air flow could be provided between a surface of the sensor assembly and the sheet to at least partially control a distance of the sheet from the surface of the sensor assembly and/or an angle at which the sheet passes the surface of the sensor assembly.

Abstract: An image-based measurement technique that directly measures the crepe pattern on a moving sheet employs a suitable arrangement of illumination, optical elements, and an imaging device to obtain digital images of the sheet surface. The image resolution is sufficient to represent tissue crepe folds at the scale of the crepe. A spectral analysis of some or of all the images reveals the crepe folding pitch. Further analysis of the image optionally reveals other crepe structural parameters, such as the distribution of crepe fold orientation angles and distribution of linear fold lengths. Corrective actions can be implemented in response to changes in the crepe structure. The pitch of creping is the primary parameter for describing the crepe pattern; in addition, analyzing the images with a gradient operator can yield information regarding the orientation of the crepe folds and distribution of angles of the crepe furrows on the hood side or equivalently of the crepe seams on the cylinder side.

Abstract: A system and method for color measurements or other spectral measurements of a material are provided. An illuminating device generates light for illuminating a sample of material. A detector detects light that has interacted with the sample and provides a measurement of the light that has interacted with the sample. A controller adjusts a duty cycle of the illuminating device to control the illumination of the sample. The measurement could be used by an analyzer to determine a spectral characteristic of the sample (such as a color of the sample). The determination of the spectral characteristic could be done without using any measurement of light that has not interacted with the sample. One or multiple light emitting diodes (LEDs) could be used to illuminate the sample, and the duty cycle of individual LEDs or groups of LEDs could be adjusted.

Abstract: An image-based technique that measures the orientation of fibers in a moving web of nonwoven material. At least four light spots on one side of the web are illuminated essentially simultaneously with at least four plane-polarized incident substantially perpendicular light beams having different polarization characteristics. Dispersion of the excident light spots is measured on the opposite side of the web along at least one linear section which is at a known angle relative to the plane of polarization of the corresponding plane-polarized incident light beam, wherein at least one such linear section lies substantially across the center of the transmitted excident light spot and extends substantially across the width of the transmitted excident light spot. Variations in the dispersion of the transmitted excident light spot for the at least four plane-polarized light beams are calculated, and the fiber orientation is estimated from the variations.