Abstract:
A spectroscopic method using either tunable or preset non-tunable thin-layered devices or a combination of both to modulate compressed-sensing-compliant, spectral modulations and to use intensity measurements of each respective spectral modulation to numerically reconstruct an estimated spectral distribution of the spectral signal such that the estimated spectral distribution is characterized by a totality of spectral bands exceeding the number of spectral modulations by about one half an order-of-magnitude or more.
Abstract:
Techniques for hyperspectral imaging using a spatial light modulator having a plurality of pixels, including encoding electromagnetic radiation incident a first pixel at a first location and a second pixel at a second location into a first modulated signal having a first modulation frequency and a second modulated signal having a second modulation frequency, the first modulation frequency being different than the second modulation frequency. A sum of intensities of at least the first modulated signal and the second modulated signal is measured at a plurality of optical frequencies and a transform is applied to the sum to obtain an intensity of electromagnetic radiation incident each of the first location and the second location for each of the plurality of optical frequencies.
Abstract:
A spectroscopy system comprising at least two laser modules, each of the laser modules including a laser cavity, a quantum cascade gain chip for amplifying light within the laser cavity, and a tuning element for controlling a wavelength of light generated by the modules. Combining optics are used to combine the light generated by the at least two laser modules into a single beam and a sample detector detects the single beam returning from a sample.
Abstract:
An absorption spectroscopy instrument with a light source for providing a beam of light, a modulator to produce a modulated beam of light, a high finesse optical cavity, means for injecting the modulated beam of light off-axis into the high finesse optical cavity and a detector positioned to receive and measure light exiting through said optical cavity. The detector may be a highly sensitive and high bandwidth detector. The modulator may be a one or two-tone modulator having means, such as a plurality of RF synthesizers, for modulating the light source by one or two tones. If one tone of applied modulation is used, the frequency is larger than the absorption bandwidth of the target chemical. In the case where two tones are used, the first frequency is larger than the absorption bandwidth of the target chemical and the second frequency is small relative to the first frequency.
Abstract:
A multidimensional spectrometer encodes frequency information into laser pulses so that a frequency insensitive detector may be used to collect data for a multi-dimensional spectrograph only from intensity information and knowledge of a modulation providing the encoding. In one embodiment the frequency encoding may be done by a conventional interferometer greatly simplifying construction of the spectrometer.
Abstract:
Methods and systems for real time, in situ monitoring and blending of hydrocarbon fluids from multiple transmission lines feeding into a downstream line or vessel are described. The method and system include the scanning of the NIR range on fluids within each of at least two transmission lines. The spectroscopic optical data from the two scans is used to determine flow rates of the fluids from each transmission line to, for example, achieve a desired energy content, physical properties, or speciation in the blended fluid.
Abstract:
Methods and apparatus for the active control of a wavelength-swept light source used to interrogate optical elements having characteristic wavelengths distributed across a wavelength range are provided.
Abstract:
Methods and systems for real time, in situ monitoring of fluids, and particularly the determination of both the energy content and contaminants in a gas or oil transmission facility, are provided. The system may include two separate scanning sources to scan two different, but overlapping, NIR ranges, or may involve two separate scans from a single scanning spectroscopy source. The first scan ranges from approximately 1550 nm up through 1800 nm and a second scan concurrently scans at a high resolution across a band from approximately 1560-1610 nm, the wavelength of interest for hydrogen sulfide (though similar scans are contemplated in alternative wavelength ranges for alternative contaminants). The second scan may provide very narrow (0.005 nm) step resolution over just the wavelength of interest for the contaminant and may scan at a substantially higher power level. The spectroscopic optical data from the two scans, however obtained, must then be combined into an analytical processing module containing models that analyze the multi-scan data and yield both energy content and contaminant quantitative data.
Abstract:
A spectroscopic measurement device includes a variable wavelength interference filter provided with a first reflecting film, a second reflecting film, and an electrostatic actuator for changing a gap amount of a gap between the first reflecting film and the second reflecting film, a detection section adapted to detect the light intensity of the light taken out by the variable wavelength interference filter, a voltage setting section and a voltage control section for applying an analog voltage varying continuously to the electrostatic actuator, a voltage monitoring section for monitoring the voltage applied to the electrostatic actuator, a storage section for storing V-λ data, and a light intensity acquisition section for obtaining the light intensity detected by the detection section at a timing at which the light transmitted through the variable wavelength interference filter has the measurement target wavelength based on the voltage monitored by the voltage monitoring section.
Abstract:
According to embodiments, techniques for using continuous wavelet transforms and spectral transforms to identify pulse rates from a photoplethysmographic (PPG) signal are disclosed. According to embodiments, candidate pulse rates of the PPG signal may be identified from a wavelet transformed PPG signal and a spectral transformed PPG signal. A pulse rate may be determined from the candidate pulse rates by selecting one of the candidate pulse rates or by combining the candidate pulse rates. According to embodiments, a spectral transform of a PPG signal may be performed to identify a frequency region associated with a pulse rate of the PPG signal. A continuous wavelet transform of the PPG signal at a scale corresponding to the identified frequency region may be performed to determine a pulse rate from the wavelet transformed signal.