61 results about "Modulation spectroscopy" patented technology

Processing of information signals separated according to modulation and carrier components in a more controlled way is made possible by a device for processing an information signal including a unit for converting the information signal to a time / spectral representation by block-wise transforming of the information signal and a unit for converting the information signal from the time / spectral representation to a spectral / modulation spectral representation, wherein the unit for converting is designed such that the spectral / modulation spectral representation depends on both a magnitude component and a phase component of the time / spectral representation of the information signal. A unit then performs a manipulation and / or modification of the information signal in the spectral / modulation spectral representation to obtain a modified spectral / modulation spectral representation. A further unit finally forms a processed information signal representing a processed version of the information signal based on the modified spectral / modulation spectral representation.

The invention relates to a method and a device for detecting multi-component gas through a semiconductor laser modulated spectrum. A temperature controller and an adjustable constant flow source are adopted for driving a semiconductor laser, a scanning signal source generates a scanning control signal and injects the scanning control signal into the temperature controller to realize continuous change of temperature, so as to drive the semiconductor laser to output laser with continuous wavelength change, wherein the output laser is divided into two paths, one path of laser and the other path of laser passing through a gas absorption cell are received by a balanced detector commonly, and the scanning signal source synchronously triggers a data acquisition card to acquire a signal output by the balanced detector and input the signal to a computer for processing, so as to obtain the multi-component detection result. According to the method and the device for detecting the multi-component gas through the semiconductor laser modulated spectrum, the range of the continuous output wavelength of the semiconductor laser is expanded and the defects of narrow range of the continuous output wavelength and single detected gas type of a current driving laser are overcome, therefore, the method and the device for detecting multiple gases simultaneously by the single semiconductor laser are provided; the multi-component gas detection cost is reduced, the detection efficiency and the detection reliability are improved, and the method and the device are used for the monitoring and detecting industry of various gases.

An optical modulation spectroscopy system comprises a probe beam source and components for directing the probe beam at a sample. It also may comprise a modulated pump beam source and components for directing a modulated pump beam at the sample. A dispersive system may disperse the reflected probe beam into constituent wavelengths to provide dispersed beams. A detector array may detect multiple dispersed reflected probe beams and processes a signal corresponding to each. Thus, measurement may be multiplexed for very fast performance.

A polarization modulation photoreflectance technique has been developed for optical characterization of semiconductor electronic interfaces. By using a laser source in conjunction with polarization state modulation, a polarization modulation spectroscopy technique may be used to characterize the optical response of semiconductor materials and structures. Disclosed methods and instruments are suitable for characterization of optical signatures of electronic interfaces, including characterization of electric fields at semiconductor interfaces.

A spectrometer and spectrometry method comprising modulating a light source with a carrier waveform multiplied by an envelope function, directing light from the light source through a sample region and to a photodetector, and demodulating current from the photodetector at a reference frequency. Also a method for computing a modulation waveform comprising specifying a target detection efficiency in a Fourier space, computing a response of a waveform that comprises a carrier wave multiplied by an envelope function, and modifying the envelope function using nonlinear optimization means to minimize a difference between the computed response and a predetermined target detection efficiency.

The invention establishes a calibration-free modulation spectrum measuring software system based on a tunable diode laser absorption spectrum by virtue of a wavelength modulation technique adapted to a severe environment. The system comprises a digital phase-locking signal demodulation module, a modulation spectrum simulation module and a measured parameter extraction module which comprise 14 sub-modules. The system has the specific functions that a photoelectric signal is demodulated by virtue of a digital phase-locking algorithm so as to obtain a harmonic signal; a simulation database of the harmonic signal can be obtained by carrying out accurate theoretical calculation; the speed, temperature and constituent concentration of a flow field can be extracted by combining the harmonic signal with the simulation database.

An optical modulation spectroscopy system comprises a probe beam source and components for directing the probe beam at a sample. It also may comprise a modulated pump beam source and components for directing a modulated pump beam at the sample. A dispersive system may disperse the reflected probe beam into constituent wavelengths to provide dispersed beams. A detector array may detect multiple dispersed reflected probe beams and processes a signal corresponding to each. Thus, measurement may be multiplexed for very fast performance.

The invention discloses a spectral analysis type high-precision on-line detector for gas and liquid detection. The spectral analysis type high-precision on-line detector comprises a detection sensor probe, a detector host, and a laser device, a circuit board and a power supply battery which are mounted in a detector host shell, and a display screen, an alarm device and a communication interface which are arranged outside the shell. By the adoption of a light intensity modulation technology, and due to concentration calculation on a modulation spectrum subjected to wavelet analysis, the spectral analysis type high-precision on-line detector for gas and liquid detection has the characteristics of high detection sensitivity, high detection stability, short detection time, high detection precision and the like. According to the on-line detector, an optical fiber is connected with the detection sensor probe, so that the distance can be 4KM; the detector can be used in a fixed or portable state; when the detector is applied to gas detection, (a single or multiple serial connected) handheld, open and fixed gas probes can be adopted.

There is provided in one embodiment of the invention a method for analyzing a sample material using surface enhanced spectroscopy. The method comprises the steps of imaging the sample material with an atomic force microscope (AFM) to select an area of interest for analysis, depositing nanoparticles onto the area of interest with an AFM tip, illuminating the deposited nanoparticles with a spectrometer excitation beam, and disengaging the AFM tip and acquiring a localized surface enhanced spectrum. The method may further comprise the step of using the AFM tip to modulate the spectrometer excitation beam above the deposited nanoparticles to obtain improved sensitivity data and higher spatial resolution data from the sample material. The invention further comprises in one embodiment a system for analyzing a sample material using surface enhanced spectroscopy.

There is provided in one embodiment of the invention a method for analyzing a sample material using surface enhanced spectroscopy. The method comprises the steps of imaging the sample material with an atomic force microscope (AFM) to select an area of interest for analysis, depositing nanoparticles onto the area of interest with an AFM tip, illuminating the deposited nanoparticles with a spectrometer excitation beam, and disengaging the AFM tip and acquiring a localized surface enhanced spectrum. The method may further comprise the step of using the AFM tip to modulate the spectrometer excitation beam above the deposited nanoparticles to obtain improved sensitivity data and higher spatial resolution data from the sample material. The invention further comprises in one embodiment a system for analyzing a sample material using surface enhanced spectroscopy.

A modulation spectroscopy system (1) directs a probe beam (11) onto a sample (10), the reflected probe beam being collected by a collector (7) and processed by a detector (8). A pump beam generated by a source (4, 5) directs a pump beam (13) onto the sample at the same spot as the probe beam. However, it also switches the pump beam via a path (14) onto an adjacent location not overlapping the probe spot. This is referred to as spatial modulation. A cylindrical lens (16) in the collection subsystem (7) collects reflected light including luminescence from both pump beam spots simultaneously, so that the luminescence becomes a d.c. signal which can be easily eliminated, including means from the modulator for varying pump beam intensities and positions. This provides means to reject the unwanted background luminescence signal as well as improvement to the signal to noise ratio.

The invention provides a method for achieving nonuniform combustion field gas parameter quantitative measurement based on the modulated spectrum technology. The method comprises a wavelength modulated spectrum measurement step, a wavelength modulated spectrum fitting step and a step of calculating gas parameters in a nonuniform flow field. According to the specific content of the method, an absorption spectral line with the line strength linearly changing along with temperature within the measured temperature range is selected; transmission light intensity signals are measured through tests, and harmonic signals measured through the tests are obtained; the integral optical density, Gaussion line width and Lorentz line width are adopted as free variables, and the harmonic signals of the spectral line are fit based on the least square method; the gas parameters in the nonuniform combustion field are calculated.

Processing of information signals separated according to modulation and carrier components in a more controlled way is made possible by a device for processing an information signal including a unit for converting the information signal to a time / spectral representation by block-wise transforming of the information signal and a unit for converting the information signal from the time / spectral representation to a spectral / modulation spectral representation, wherein the unit for converting is designed such that the spectral / modulation spectral representation depends on both a magnitude component and a phase component of the time / spectral representation of the information signal. A unit then performs a manipulation and / or modification of the information signal in the spectral / modulation spectral representation to obtain a modified spectral / modulation spectral representation. A further unit finally forms a processed information signal representing a processed version of the information signal based on the modified spectral / modulation spectral representation.