Provided is an identification method of plastic microparticles, including: performing an infrared analysis on plastic microparticles to identify whether the plastic microparticles include polyethylene terephthalate, polyethylene, polypropylene, or nylon 66, wherein the identification is to determine whether the plastic microparticles have a characteristic peak of each plastic, and the characteristic peak is selected from signals that do not overlap and interfere with each other in the infrared spectrum signals of each plastic.

A method of calibrating a driving parameter of an optical component across an operating wavelength range of the component. The method comprises placing a layer of material in a light path, the layer of material being substantially planar and substantially transparent and having a thickness of the order of wavelengths in said range and operating said component to vary said driving parameter whilst detecting light transmitted through said layer of material to obtain driving parameter versus light intensity data. The obtained data is then compared with characterizing data previously derived for said layer of material in order to calibrate said driving parameter.

A method of processing two dimensional optical spectra, such as echelle spectra, is disclosed. The optical spectra comprise sections having a relatively high intensity separated by borders having a relatively low intensity. The optical spectra have been digitized (61) by a detector. The method comprises denoising (62) an optical spectrum, searching (64) for at least one series of neighboring local extrema of the optical spectrum, fitting (65) a line through each series of neighboring local extrema, each line representing a section, identifying (67) any peaks and their respective locations, and storing (68) the lines and the locations of any peaks.

Systems, devices, and methods of analyzing an interfered peak of a sample spectrum is disclosed. The sample spectrum may be generated using a detector of an optical spectrometer. The interfered peak may be produced by a plurality of spectral peaks of different wavelengths. The method may include generating interfered curve parameters representative of the peak shape of each spectral emission in the interfered peak based at least in part on a model of expected curve parameters for the optical spectrometer and a location of the interfered peak on the detector of the optical spectrometer; fitting a plurality of curves to the interfered peak, each curve corresponding to one of the plurality of spectral emissions of different wavelengths forming the interfered peak, wherein each curve is fitted using the interfered curve parameters provided by the model of expected peak parameters; and outputting the plurality of curves for further analysis.

A spectrum measurement instrument is configured to measure a wavelength of pulse laser light and includes a mercury lamp configured to encapsulate natural mercury including a plurality of isotopes and output reference light; a spectrometer located on an optical path of the reference light and the laser light and configured to receive the reference light and output a first spectral waveform; and a processor being accessible to a template waveform of a spectrum including a plurality of peaks of a known waveform of the reference light, and configured to perform pattern matching using the first spectral waveform and the template waveform and identify a first peak position corresponding to one of the plurality of peaks of the first spectral waveform.

A method includes, with a Raman spectrometer: determining a measured spectrum; determining a second derivative of a difference spectrum function corresponding to a difference between the measured spectrum and a product of a scaling coefficient and a reference spectrum of contributions of interfering influences included in the measured spectrum; determining a coefficient value of the scaling coefficient minimizing an error function including a term corresponding to an error of the difference spectrum function due to peaks included in the reference spectrum, the term including a sum of areas enclosed underneath the second derivative in all spectral regions in which the second derivative is positive, and/or a sum of areas enclosed underneath the second derivative in all spectral regions in which the second derivative is negative; and determining a Raman difference spectrum corresponding to the difference between the measured spectrum and a product of the coefficient value and the reference spectrum.

A spectroscopic device includes: an analysis optical system; a length measurement optical system; and a calculation device. The analysis optical system includes a moving mirror and a first light receiving element. The length measurement optical system includes a second light source configured to emit laser light, a gas cell with a gas that absorbs light of a predetermined wavelength sealed therein and configured to cause the laser light to be incident thereon, an emitted light amount detection unit configured to detect an amount of light emitted from the gas cell and output an emitted light amount detection signal, a light source control unit configured to control a wavelength of the laser light based on the emitted light amount detection signal, and a length measurement unit configured to use the laser light to obtain a displacement signal corresponding to a position of the moving mirror, and the calculation device includes a moving mirror position calculation unit, a light intensity calculation unit, and a Fourier transform unit configured to generate a spectral pattern.

Methods of photodiode array spectrometer calibration include acquiring a first spectrum using a first spectral source of a spectrometer; finding spectral data points at pixel locations from the first spectrum; replacing the first spectral source with a second spectral source in the spectrometer; finding spectral data points at pixel locations using the second spectral source; selecting one or more of the spectral data points; generating a calibration curve by fitting the selected spectral data points to one or more functions of the calibration curve; and using the selected spectral data points and the calibration curve to calibrate the spectrometer.