fibre optic probe
A. A. Balashov, V. A. Vagin, O. V. Chitrov
The paper discusses a new spectroscopy direction – Fourier fiber-optic spectroscopy, its features and advantages.
The development of infrared fiber-optic technology has led to the emergence of fiber-optic spectral systems. Initially, infrared fiber-optic probes were used as a prefix for typical laboratory spectrometers. Then there were spectrometers targeted only to work with the probes. There is a broad area of application of such devices – determination of composition of understood liquid and gaseous mixtures (required both for quality control of raw and finished products in industrial production, and for optimization of chemical production processes), medical diagnostics, environment pollution monitoring, scientific research, etc.
Fourier spectrometer is most effective infrared spectrometer. Therefore, development and creation of specialized fiber-optic Fourier infrared spectrometers was. But use of the fiber-optic probes required specific characteristics of the corresponding Fourier spectrometer:
Fiber-optic probe aperture is limited by the fiber diameter and distribution leaving the fibers of radiation with respect to the corner what limits, real of the spectrometer aperture operating with such a probe;
Spectral range of the work of the spectrometer under consideration is determined by the area of the effective fiber transmission;
A lot of energy optical fiber in the average infrared range absorbs quite, so the length of the corresponding probe does not exceed a few meters;
Fiber Fourier spectrometer allows the use of fiber-optic bundles (collected by several individual optical fiber), allowing for simultaneous work with multiple probes;
Fourier spectrometer allows to work effectively by using the multiple receivers simultaneously (or matrix elements reception), which opens the door for good and varied work with multifiber probes.
Scientific Technological Center of Unique Instrumentation of RAS designed and manufactured in the fiber-optic Fourier spectrometer is discussed. It allows you to measure within the sample under consideration (with the help of the fiber-optic probe), it is small size and high performance. Its main technical characteristics are a 600 – 3300 cm-1 spectral range (actual range is determined by bandwidth used by the probe), a limiting resolution – 2 cm-1; accuracy of the wave numbers of ± 0.1 cm-1; time of setting operating mode – not more than 15 minutes, power consumption – not more than 100W, the mass of the device (without a computer ) – 4 kg; outline dimensions the Fourier Spectrometer – 250 x 200 x 200 mm.
The main types of the fiber-optic probes, used in the middle infrared range (NPVO probe, fiber gas sensor, the probe measuring the optical reflection). They use two main types of fiber – chalcogenide fibers based on the composition of As-S and working in the spectral range of 2 to 6 microns; polycrystalline fibers for the middle infrared range witch are made of solid solutions of silver halogenides and working in a range from 4 microns to 18 microns.
Examples of spectra recorded with the help of these probes by the fiber-optic Fourier transform spectrometer.