Abstract:
A spectrometer (10) includes a two-dimensional array of modulatable microm-irrors (18), a detector (20), and an analyzer (22). The micro-mirrors are positioned for receiving individual radiation components forming a part of a radiation source. The micro-mirrors are modulated at different modulation rates in order to reflect individual radiation components at known and different modulation rates. The micro-mirrors combine a number of the reflected individual radiation components and reflect them to the detector. The detector receives the combined radiation components and creates an output signal. The analyzer is coupled to the detector to receive the output signal and to analyze at least some of the individual radiation components making up the combined reflection. By using a micro-mirror array that modulates the radiation components at different rates, all of the radiations components can be focused onto a single detector to maximize the signal-to-noise ratio of the detector.
Abstract:
A method for characterizing samples having fluorescent particles, by monitoring fluctuating intensities of radiation emitted by said particles in at least one measurement volume, the monitoring being performed by at least one detection means, said method comprising the steps of: a) measuring in a repetitive mode a length of time intervals between photon counts, b) determining a function or a series of functions of the length of said time intervals, c) determining a function of at least one specific physical property of said particles on basis of said function or said series of functions of the length of time intervals, by finding a close fit between the experimentally determined and a theoretical function or series of functions of the length of said time intervals, the latter of which takes into account parameters of the spatial brightness function characteristic for the optical set-up.
Abstract:
A confocal spectral imaging system comprises a light source (110), a light modulator (120) forming an illumination aperture and directing an illumination pattern to conjugate object locations, and analyzing means (150) with a detection aperture, dispersive elements and a detector (156), wherein the illumination and detection apertures are in conjugate optical planes, and the light modulator consists of an array of light modulator elements, a group of which being arranged according to the illumination pattern and forming the illumination aperture, and are controlled such that the illumination pattern is directed to time-dependent changing conjugate locations of the object. A programmable light source comprises a white light source, dispersion means and a spatial light modulator with an array of individually time-dependent controllable modulator elements being illuminated with the dispersed light and providing a position selective transmittivity or reflectivity, so that a light with a predetermined wavelength distribution passes the light modulator.
Abstract:
An apparatus and method for monitoring a stability of a spectrum are provided. The apparatus for monitoring stability of a spectrum includes a spectroscope configured to measure a spectrum of a sample and a processor configured to calculate a similarity change index of the measured spectrum and to determine the stability of the measured spectrum by analyzing the calculated similarity change index.
Abstract:
A method for determining a weed percentage in a viewing section (10) of a field (20) is described. Actual spectral information is acquired by means of at least one optical viewing section sensor (12a, b) which is directed to the viewing section (10). Furthermore, reference spectral information is acquired by means of an optical reference sensor (32), which is directed to a reference section (30) of the same soil surface (22). A difference between the actual spectral information and the reference spectral information is determined. Finally, the difference is applied to the weed percentage by means of a predefined image. Furthermore, an agricultural control device (100) is described which is suitable for the implementation of the method.
Abstract:
A spectrometer for identifying a mixture is provided. The spectrometer includes a detector configured to generate a signal based on an interaction of light with a sample of the mixture, and a memory device having a library and a correlation matrix stored therein, wherein the library includes a plurality of spectra, each spectrum associated with a respective compound, and wherein the correlation matrix includes a correlation between each possible pair of spectra in the library. The spectrometer further includes a processor coupled to the memory device and configured to determine a spectrum of the mixture based on the signal generated by the detector, calculate a correlation vector that includes a correlation between the mixture spectrum and each spectrum in the library, and identify the mixture based on the correlation matrix and the correlation vector.
Abstract:
There is provided a method for referencing and correcting the beating spectrum generated by the interference of the components of a frequency comb source. The proposed method allows monitoring of variations of a mapping between the source and the beating replica. This can then be used to compensate small variations of the source in Fourier transform spectroscopy or in any other interferometry application in order to overcome the accuracy and measurement time limitations of the prior art. Constraints on source stability are consequently reduced.
Abstract:
The invention relates to a method for detecting at least one chemical compound V that is contained in a medium (312). Said method has a verification step (420), in which the presence of the compound V in the medium (312) is determined. In addition, the method has an analysis step (424), in which a concentration c of the chemical compound or compounds V is determined. The verification step comprises the following sub-steps: (a1) the medium (312) is irradiated with first analysis radiation (316) of a variable wavelength λ, said wavelength λ having at least two different values; (a2) a spectral response function A(λ) is generated using the radiation (324) that has been absorbed and/or emitted and/or reflected and/or scattered by the medium (312), in response to the first analysis radiation (316); (a3) at least one spectral correlation function K(δλ) is formed by comparing the spectral response function(s) A(λ) with at least one model function R(λ + δλ), in which said model function(s) R(λ) represent(s) a spectral measured function of a medium (312) that contains the chemical compound V and δλ is a co-ordinate shift; (a4) the spectral correlation function(s) K(δλ) is examined in a model identification step (418) and conclusions are drawn as to whether the chemical compound(s) V is or are contained in the medium (312). The analysis step (424) has the following sub-steps: (b1) the medium (312) is irradiated with at least second analysis radiation (318) that has at least one excitation wavelength λEX; (b2) at least one spectral analysis function B(λEX, λRES) is generated using the radiation (326) of the response wavelength λRES that has been absorbed and/or emitted and/or reflected and/or scattered by the medium (312), in response to the second analysis radiation (318) of wavelength λEX and conclusions concerning the concentration c are drawn.