Control of an amplitude of a signal applied to rods of a quadrupole is described. In one aspect, a mass spectrometer includes an amplifier circuit that causes a radio frequency (RF) signal to be applied to the rods of the quadrupole based on an amplifier RF input signal. An analog-to-digital converter (ADC) can generate a digital representation of the RF signal. A controller circuit can receive the digital representation and adjust an amplitude of the amplifier RF input signal based on differences between an amplitude of a fundamental frequency of the RF signal being different than an expected amplitude.

Disclosed herein are systems and methods of obtaining a derivative Raman spectrum using an excitation or Raman pump beam whose wavelength is modulated in any suitable manner such as, for example, stochastically. Shifting the wavelength of the input excitation by a small amount in approaches like SERDS can isolate the Raman scatter from other spectral artifacts and reduce the false detection rate. For example, an input excitation sequence can be correlated with the response of an individual pixel of a detector. From this, pixels that have captured Raman scattered photons can be separated from pixels capturing non-Raman photons. These techniques can be expanded to other fields and/or types of spectroscopies that utilize a dispersive element detector with time-dependent spectral features.

Aspects of the disclosure relate to classifying a target object. An electronic device may transmit a detection signal and receive a reflection signal reflected from the target object. The electronic device then determines, based on one or more features of the reflection signal, a category of the target object and adjusts at least one transmission parameter based on the category. The electronic device then transmits an adjust signal using the transmission parameter. Other aspects, embodiments, and features are also claimed and described.

A terahertz spectrometer includes a terahertz-wave emitter and a terahertz receiver elements. The terahertz wave generated by means of generating beat frequency corresponding to the difference between two rapidly tunable continuous wave lasers. A difference in time exists between the interrogating signal and the reference signal at the receiver end side, which corresponds to intermediate frequency (IF), not centered around the baseband, i.e. zero Hertz. The offset step size of the intermediate frequency from zero Hertz is linearly correlated to the position of the interrogated object position.

Method and gas analyzer for measuring the concentration of a gas component in a measurement gas, a wavelength-tunable laser diode is actuated with a current, one part of the light generated by the laser diode is guided through the measurement gas to a measuring detector to generate a measuring signal, the other part of the light is guided to a monitor detector to generate a monitor signal, the current is varied in periodically consecutive scanning intervals to scan an absorption line of interest of the gas component as a function of the wavelength, the current is further modulated with a radio-frequency noise signal having a lower cut-off frequency selected as a function of the properties of the laser diode and high enough to ensure no wavelength modulation occurs and the measuring signal is correlated with the monitor signal and then evaluated to generate a measurement result.

Embodiments of the disclosure are drawn to apparatuses and methods for anomalous gas concentration detection. A spectroscopic system, such as a wavelength modulated spectroscopy (WMS) system may measure gas concentrations in a target area. However, noise, such as speckle noise, may interfere with measuring relatively low concentrations of gas, and may lead to false positives. A noise model, which includes a contribution from a speckle noise model, may be used to process data from the spectroscopic system. An adaptive threshold may be applied based on an expected amount of noise. A speckle filter may remove measurements which are outliers based on a measurement of their noise. Plume detection may be used to determine a presence of gas plumes. Each of these processing steps may be associated with a confidence, which may be used to determine an overall confidence in the processed measurements/gas plumes.

Apparatuses, methods, and systems for detecting a sample are disclosed. One method includes generating, by a tunable light source, a beam of electro-magnetic radiation, wherein a wavelength of the beam of electro-magnetic radiation is tuned to operate at a plurality of wavelengths. At least a portion of the beam of electro-magnetic radiation is directed to pass through the sample and a reference substance. The system detector is configured to sense at least the portion of the beam of electro-magnetic radiation after passing through the sample and the reference substance. The processor operates to receive information related to intensity or amplitude of the sensed beam of electro-magnetic radiation after passing through the sample and the reference substance and detect an amount of the sample based on the received information related to the intensity or amplitude of the sensed beam of the electro-magnetic radiation.

A system includes first and second radiation sources, first and second detectors, a signal digitizer, a controller, and an analyzer. The first and second radiation sources generate respective first and second beams of radiation to irradiate a target. The first beam and second beams each include a first wavelength operated at a first modulation frequency and a second wavelength operated at a second modulation frequency. The first and second detectors each include a photo-sensitive element that generate first or second detection signals, a Faraday shielding enclosure, a signal amplifier, and a frequency mixer to frequency-adjust the first or second detection signals. The controller provides timing information to inform an activation scheme of the first and second radiation sources and corresponding radiation detection events at the first and second detectors. The analyzer analyzes the first and second detection signals and determines at least amplitude and phase information of the scattered radiation.

Apparatuses, methods, and systems for detecting a sample are disclosed. One method includes generating, by a tunable light source, a beam of electro-magnetic radiation, wherein a wavelength of the beam of electro-magnetic radiation is tuned to operate at a plurality of wavelengths. At least a portion of the beam of electro-magnetic radiation is directed to pass through the sample and a reference substance. The system detector is configured to sense at least the portion of the beam of electro-magnetic radiation after passing through the sample and the reference substance. The processor operates to receive information related to intensity or amplitude of the sensed beam of electro-magnetic radiation after passing through the sample and the reference substance and detect an amount of the sample based on the received information related to the intensity or amplitude of the sensed beam of the electro-magnetic radiation.

The invention provides a chirped laser dispersion spectrometer having two tunable lasers each with a bias current supply, a chirp signal source to provide a matching chirp pattern, a beam splitter to produce a single beam from the two first and second tunable lasers and active-phase locking means to render the two beams phase coherent and to produce a radio frequency carrier signal capable of programmable phase modulation by means of an optical beat signal. The invention also provides a method for generating at least two optical frequency signals for use in a frequency modulation spectroscopy (FMS) process for the detection and/or measurement of molecular species in a gas mixture and a method for generating at least two optical frequency signals for use in a chirped laser dispersion spectroscopy (CLaDS) process for the detection and/or measurement of molecular species in a gas mixture. The invention provides an efficient and cost-effective CLaDS system which maintains optical modulation whilst enabling greater change of the modulation frequency.