Embodiments are disclosed for terahertz spectroscopy and imaging in dynamic environments. In an embodiment, a method comprises emitting a continuous electromagnetic (EM) wave in a terahertz (THz) frequency band into a dynamic environment. The EM THz wave is reflected off an object in the environment. A spectral response of a received signal indicative of the reflected EM wave is determined that includes absorption spectra at a frequency in the THz frequency band. The absorption spectra is indicative of a transmission medium in the environment. The spectral response of the received signal is compensated for fixed and frequency-specific losses. The compensated absorption spectra is compared with known absorption spectra of target transmission mediums. Based on results of the comparing, a particular target transmission medium is identified as being the transmission medium in the environment. The absorption spectra loss is used to determine a concentration level of the target transmission medium.

A dynamic Raman signal acquisition apparatus, system, and method involving: an excitation light source operable at a designated irradiation power and for a designated acquisition time for each Raman data acquisition; a Raman probe operatively associated with said excitation light source to irradiate the biological tissue at said designated irradiation power and for said designated acquisition time, and capture an optical Raman response therefrom; a spectrometer operable to spectrally analyze said optical Raman response; and a controller in operative communication with said excitation light source and said spectrometer to automatically adjust at least one signal acquisition parameter.

A method for the determination and correction of background signals in a spectrum, consisting of signals of a plurality of spectral points, characterized by the steps of: Calculating at least three statistic or analytic functions of the signal values of the spectrum, attributing probabilities P.sub.i(band) for the presence of bands to each point in each of the calculated functions: Adding the probabilities P.sub.i(band) up to an overall probability P.sub.i(band) from all calculated functions for each point; calculating a probability P(background) for the presence of background for each point in the spectrum from said overall probability P.sub.i(band) according to P(background)=1P.sub.i(band) wherein negative values are set to zero; and calculating a fit of the signal values at all points of the original spectrum wherein the signal in each point is taken into account in the fit only with the respective probability for the presence of background P(background), and subtraction of the background function determined in such a way from the signal values of the original spectrum in order to generate a background corrected spectrum.

Various embodiments disclosed herein describe an infrared (IR) imaging system for detecting a gas. The imaging system can include an optical filter that selectively passes light having a wavelength in a range of 1585 nm to 1595 nm while attenuating light at wavelengths above 1600 nm and below 1580 nm. The system can include an optical detector array sensitive to light having a wavelength of 1590 that is positioned rear of the optical filter.

A method of processing an analog signal includes receiving, into signal processing circuitry from compensation circuitry, an offset compensation signal, the offset compensation signal having (i) a polarity opposite a polarity of a gain error of the signal processing circuitry and (ii) a magnitude equal to a nominal compensation value plus a deviation. The method includes generating, by the signal processing circuitry, an output signal based on an analog signal received into the signal processing circuitry, including applying the offset compensation signal to an intermediate signal generated by the signal processing circuitry. The method includes scaling the output signal based on the deviation between the magnitude of the offset compensation signal and the nominal compensation value.

Various embodiments disclosed herein describe an infrared (IR) imaging system for detecting a gas. The imaging system can include an optical filter that selectively passes light having a wavelength in a range of 1585 nm to 1595 nm while attenuating light at wavelengths above 1600 nm and below 1580 nm. The system can include an optical detector array sensitive to light having a wavelength of 1590 that is positioned rear of the optical filter.

An improved method for integrating curve peaks as compared to techniques such as the trapezoidal rule wherein integration parameters are at fixed x-axis positions. Integration parameters are instead specified relative to a peak center, which allows the peak to shift over time due to hardware changes, temperature fluctuation, pressure changes, etc., while maintaining integration parameters at optimal locations for that peak. As such, the present disclosure finds particular utility in spectroscopy wherein, in the case of Raman spectroscopy, for example, specific wavenumber shift locations may drift over time, leading to inaccurate results based upon absolute integration parameters.

An improved method for integrating curve peaks as compared to techniques such as the trapezoidal rule wherein integration parameters are at fixed x-axis positions. Integration parameters are instead specified relative to a peak center, which allows the peak to shift over time due to hardware changes, temperature fluctuation, pressure changes, etc., while maintaining integration parameters at optimal locations for that peak. As such, the present disclosure finds particular utility in spectroscopy wherein, in the case of Raman spectroscopy, for example, specific wavenumber shift locations may drift over time, leading to inaccurate results based upon absolute integration parameters.

A gas analysis system with an FTIR spectrometer preferably utilizes a long path gas cell, a narrow band detector, and an optical filter that narrows the detection region. The interferograms are further prevent baseline drift and analyze the resultant spectra.

An on-chip spectroscopic sensor includes a tunable diode laser. A laser driver for drives the tunable diode laser. An analyte test cavity receives a chemical sample and exposes the received chemical sample to light from the tunable diode laser. An optical detector detects light emerging from the analyte test cavity as a result of the laser exposure. A spectral analyzer determines a spectrum of the emerging light, matches and removes one or more known optical fringe patterns from the determined spectrum, and determines a composition or concentration of the chemical sample from the optical fringe pattern-removed spectrum.