Introduction to Infrared Spectrometer
The most widely used type of infrared filter currently is the Michelson interferometer scanning, known as Fourier transform infrared spectroscopy.
Infrared spectrometer is an instrument that utilizes the absorption characteristics of the detected substance towards specific wavelengths of infrared radiation to analyze chemical composition and molecular structure. Its structure mainly includes four parts: light source, spectral system, sample cell, and detection system.
Light source
The commonly used light sources for infrared spectroscopy include laser diodes, tungsten halide lamps, light-emitting diodes, etc.
Spectral system
The function of a spectral system is to convert composite light into monochromatic light, and it is the core component of an infrared spectrometer. The main spectral types include gratings, filters, interferometers, and acousto-optic tunable filters, corresponding to dispersion type infrared spectra, filter type infrared spectra, Fourier transform infrared spectra, and acousto-optic filter type infrared spectra, respectively.
1. Filter type infrared spectrometer
The filter infrared spectrometer uses interference filters to separate light, and by fixing different filters on the turntable, it can measure the infrared spectral data of multi wavelength samples. At present, the development of filtration technology is limited, and the current level of technology can only develop filtration.
2. Dispersive infrared spectrometer
Dispersion infrared spectrometer, also known as grating scanning infrared spectrometer, uses prisms or gratings for light separation. This instrument has the characteristics of full spectrum scanning and high resolution.
3. Fourier transform infrared spectrometer
The Fourier transform infrared spectrometer currently occupies a dominant position in infrared spectrometers, and the core component of the Fourier transform infrared spectrometer is the Michelson interferometer. The light emitted by the light source is collimated into parallel light and travels at a speed of 45 degrees Celsius; Angle injection beam splitter. Half of the light intensity is reflected by the beam splitter and directed towards the fixed mirror M2, while the other half of the light intensity is directed towards the moving mirror through the beam splitter. The light reflected onto the fixed and moving mirrors actually converges again. At this point, it has become coherent light with interferometric properties. When the moving mirror moves, interference light intensity with different optical path differences can be obtained.
For pure monochromatic light, cosine interference waves with varying intensity will be obtained during the continuous motion of the moving mirror, so that the detector can detect the interference pattern of the sample and obtain information on all wavelengths in the analyzed light each time. Finally, the infrared spectrum of the sample is obtained by using the ratio of the intensity of the light source after Fourier transform to the blank light source.
4. Acoustic Optical Filter (AOTF) Infrared Spectrometer
The acousto-optic filter is a spectroscopic device based on the principle of acousto-optic diffraction, using birefringent crystals with high refractive index and low sound attenuation.
Infrared spectrometer is an instrument that utilizes the absorption characteristics of the detected substance towards specific wavelengths of infrared radiation to analyze chemical composition and molecular structure. Its structure mainly includes four parts: light source, spectral system, sample cell, and detection system.
Light source
The commonly used light sources for infrared spectroscopy include laser diodes, tungsten halide lamps, light-emitting diodes, etc.
Spectral system
The function of a spectral system is to convert composite light into monochromatic light, and it is the core component of an infrared spectrometer. The main spectral types include gratings, filters, interferometers, and acousto-optic tunable filters, corresponding to dispersion type infrared spectra, filter type infrared spectra, Fourier transform infrared spectra, and acousto-optic filter type infrared spectra, respectively.
1. Filter type infrared spectrometer
The filter infrared spectrometer uses interference filters to separate light, and by fixing different filters on the turntable, it can measure the infrared spectral data of multi wavelength samples. At present, the development of filtration technology is limited, and the current level of technology can only develop filtration.
2. Dispersive infrared spectrometer
Dispersion infrared spectrometer, also known as grating scanning infrared spectrometer, uses prisms or gratings for light separation. This instrument has the characteristics of full spectrum scanning and high resolution.
3. Fourier transform infrared spectrometer
The Fourier transform infrared spectrometer currently occupies a dominant position in infrared spectrometers, and the core component of the Fourier transform infrared spectrometer is the Michelson interferometer. The light emitted by the light source is collimated into parallel light and travels at a speed of 45 degrees Celsius; Angle injection beam splitter. Half of the light intensity is reflected by the beam splitter and directed towards the fixed mirror M2, while the other half of the light intensity is directed towards the moving mirror through the beam splitter. The light reflected onto the fixed and moving mirrors actually converges again. At this point, it has become coherent light with interferometric properties. When the moving mirror moves, interference light intensity with different optical path differences can be obtained.
For pure monochromatic light, cosine interference waves with varying intensity will be obtained during the continuous motion of the moving mirror, so that the detector can detect the interference pattern of the sample and obtain information on all wavelengths in the analyzed light each time. Finally, the infrared spectrum of the sample is obtained by using the ratio of the intensity of the light source after Fourier transform to the blank light source.
4. Acoustic Optical Filter (AOTF) Infrared Spectrometer
The acousto-optic filter is a spectroscopic device based on the principle of acousto-optic diffraction, using birefringent crystals with high refractive index and low sound attenuation.