A dual-laser Raman spectrometer was developed, in which the two lasers image two different parts of the spectrum alternately on the same spectrograph. This solves the resolution/bandwidth trade-off problem of CCD Raman spectrometers, previously solved with a dual-grating technique. The dual-laser technique has, however, an additional advantage of alleviating the contradiction between sample fluorescence and detector response, which is illustrated here by applying the technique to the measurement of paper coating paste.
Raman spectorscopy was applied to study the reactions between amine and epoxy groups, which had been expected to proceed during synthesis of hybrid polymer based on three monomers: 3-aminopropyltrimethoxysilane, 3-glycidyloxypropyl-trimethoxysilane and methacryloxy-propyltrimethoxysilane. Efficiency of the investigated reaction determines the molecular structure of the organic network and consequently - mechanical and optical properties of manufactured material. An optical system developed for the real-time Raman monitoring was connected with typical glass reaction vessel and non-invasive measurements were made. Additional FT-Raman investigation was carried out to confirm obtained results. Transformation of primary amine as well as epoxy ring opening was confirmed and role of catalyzers was discussed.
A fiberoptic Raman spectroscopy system was adapted to remote measurements made in conditions typical for chemical industry. This technique was used to diagnose a process of synthesis of amine-epoxy based hybrid polymers, developed as a new class of adhesive materials for optics. Hybrids, manufactured in sol-gel technology, have a great application potential, because their properties may be formed in wide range. However, to obtain a high quality product, a strict control of the manufacturing process must be ensured. The main goal of research, presented in this paper, was to investigate the course and efficiency of the most important reactions, which takes part during the gelation -- the first step of the sol-gel process. An optical system developed for the real-time monitoring was connected with typical glass reaction vessel and non-invasive measurements were made. The results enabled to find the appropriate conditions for the reaction between amine and epoxy groups. Moreover, time of the hydrolysis of monomers and condensation of inorganic network was measured as well as efficiency of these reactions was proved to be very high.
Optical analysis techniques, infrared spectroscopy in the front end, are rapidly achieving new applications in process control. This progress is accelerated by the development of more rugged instrument constructions. This paper describes two analyzer techniques especially developed for use in demanding environments. First, the integrated multichannel detector techniques is suitable for applications where the measurement can be accomplished by using 2 to 4 wavelengths. This technique has been used to construct several compact, portable and battery-operated IR analyzers, and process analyzers which measure exactly simultaneously at each wavelength resulting in very high tolerance against rapid changes and flow of the process stream. Secondly, a miniaturized Fourier transform infrared (FTIR) spectrometer is being developed for use as an OEM module in specific process and laboratory instruments. Special attention has been paid to increase the resistance of FTIR technique to ambient vibrations. The module contains an integrated digital signal processing electronics for intelligent control of the spectrometer and for fast real time spectral data treatment. Application studies include on line measurement of the concentrations of diluted and colloidal organic detrimental substances, especially pitch components, in the circulating waters in paper machine wet end.
There have been made some attempts to transfer the advantages of FT-JR to industrial use. Commercially available research grade instruments have been large and rather expensive. However in many potential applications only medium resolution is required which means that the mirror displacement in a Michelson type interferometer remains short and computation of the Fourier transform can be executed by a small computer. Medium resolution gives also other advantages in spectrometer design simple source and detector optics less severe requirements for mirror transport and small size. We have used a Michelson type interferometer where the moving mirror is suspended by two flexures and driven by a coil actuator. Displacement of the mirror is monitored using moire transducer which is much smaller and has better thermal stability than the conventionally used HeNe laser. The beamsplitter is a standard CaF2/Si and a thermoelectrically cooled PbSe is used as the detector. In the present prototype data is transferred via parallel bus to a PC/AT compatible computer where the necessary mathematics is done. The spectral range is from 5000 to 1800 cm1 with resolution better than 8 cm1. Interferograins can be recorded several times per second and the computation time for a 2000 point spectrum is 10 seconds. Results of environmental tests carried out for the spectrometer will be presented. The results show that it is possible to construct a simple rugged and inexpensive FT-IR spectrometer
This paper discusses the advantages that can be achieved by using integrated multichannel detectors instead of the traditional filter wheel construction in process analyzers and presents four accomplished applications. Integrated multichannel detectors include several parallel detector elements each equipped with a specific interference filter and a Peltier cooler in one hermetic package. Advantages gained by filter integration are good withstanding of ambient stresses and low price due to small size. Multichannel detectors enable the use of different chopper techniques and rugged miniature and highly reliable analyzer constructions. Furthermore multichannel detectors provide exactly simultaneous measurement at each wavelength. This minimizes noise caused by rapid variations in fast moving nonhomogeneous process streams. The first application described is a two wavelength water monitor designed for on-line measurement of water content in lubricating oils. It has to meet high temperatures and high relative humidities in production plant environments. The oil analyzer is an advanced instrument that continuously measures oil content of water effluents in marine and land based applications. The peat moisture meter is a rugged portable NIR instrument constructed without any moving parts. Finally a four-wavelength NIR reflectance instrument is described. In a pilot application in a wood grinding plant the instrument with fibre optics is used to achieve a true in-line moisture measurement of the pulp stream having a speed of 15 - 40 rn/s and temperature of 125 - 145 OC. 1.