Only a Few Angles Tomography in Science and Technology

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Presented design professor, Ph.D., Phylonin O.V. in the field of tomography for scientific applications

Optical tomography, designs tomography systems, handling of initial data, the device interfacing with MS. 

Optical and structural schemes, developed and manufactured tomography

NB In the development of reconstruction algorithms as applied to a given class of the expected image sections appropriate to use the full procedure prior modeling. For these purposes a number of techniques modeling the spatial distribution of the parameters of the objects and phantoms, an example of one of them is shown below. Here, the original image at the top right, bottom left reconstructed using the convolution; algorithms for a number of projections 12, the format of reconstruction 512 x 512 elements in the mirror view.

Methods and means of tomography have been successfully used to study plasma in thermonuclear fusion, as visible; radiation and X-ray. The figure below represents the system of reconstruction of pollutant transport in a tokamak plasma (FT-2) in the region of visible light.

The main difficulty of this kind of diagnosis, is an extremely small number of projections - in this case just two. But despite this managed to develop enough effective reconstruction algorithms allow us to obtain transverse sections of the plasma in the chamber - a tomogram in the center of the picture. And no other alternative today in principle does not exist. Reconstruction quality can be seen in the image, a procedure consistent modeling allows us to assert that the relative (generalized), the error does not exceed 10% - 15%.

Small-tomography to study the parameters of arc discharges, plasma flows, plasma torches, high-pressure streams of gases and flames.

The photograph shows a sample of the first in the world of few optical tomography, the official results of operation and design were reported at the Tenth Siberian Meeting on Spectroscopy (Tomsk, 1981).

Tomograph designed for research purposes, is designed to work in optical laboratories. It allows you to receive up to 24 projections, to conduct spectral tomographic reconstruction, given the cross sections of plasma objects, can be equipped with all types of monochromators, spectrographs ISP-28, TSP-51, enter the initial information from the registration area of the spectrograph made using two-dimensional CCD cameras allow you to form an image format 320 x 200, 512 x 512, respectively, in color and b / w versions, maximum number of frames obtained in the present design 100 fps.

Optical tomography scheme for research purposes is shown in the figure below, the distinguishing feature of the proposed design is an easy choice of projections and the geometry of the collection of baseline data in the range (0 - p), (0 - 2p), and also use the technique of laser sensing of dense or dusty plasma. This design allows to obtain baseline data, as in a plane geometry and the geometry of fan-beam.

The use of laser probing dusty plasma flow to determine the quality of impurities in the stream, for example, material deposition, the volume of flow. This makes it possible to select such gas-dynamic parameters, for example, the plasma torch as a working gas pressure, current, electrode diameter, the flow of powder, etc. etc., to optimally perform the procedure of spraying the product. A separate question - shape optimization torch, for example in the development of cutting torches, including scalpel. Here the additive powder from high-temperature alloys greatly facilitates the study of plume configuration and allows you to indirectly determine the spatial distribution of temperature, density, etc. Optical scheme of few laser imager is shown in the figure below. Systems of this type should be developed not only in terms of diagnosis, but also in standard measurement systems. Developed methods and systems for collecting baseline information can simultaneously record both their own self-luminous radiation of the object and the probe radiation, and the appropriate use of spectral tomography method of registration, a principle which is illustrated in the figure below.

Opto-electronic scanner to study the large-scale high-pressure gas streams of high pressure

This scanner is designed to study the parameters of combustion processes in high-flow high-pressure gases. Number of projections can be chosen from 6 to 12, the maximum diameter of the gas facility to 3 pm Registration Package projections, including the spectral region is high-speed CCD color cameras, high-resolution conversion format 800 x 600 items.

As an example, presented a tomogram of the temperature distribution on the orthogonal cross section, reconstructed using the above-described tomography for high-temperature gas flow high pressure cross-section diameter of about 0, 76 m.

The following screenshot shows the image filtered tomogram to select the temperature gradient zone plume.

Of few optical tomograph allows to carry out laser probing of a plasma or flame - plasma facility.

Of few optical scanner is designed to study dust and; dense; plasma and flaming objects using their own glow of the object and the probe laser. In the study of flame scanner articulated with a monochromators (see Figure monochromators in the foreground). In the latter case, the restored version of the classic cross section of the radiation field transmitted through a given section. Number projections given system 6 to 12, greatest; transverse; size researched object till 40 mm. The initial information package of the projections of the spectra recorded a speed camera, or CCD, with the conversion format to 512 x 512 items. Sample Image pressurized propane butane flame is shown in the figure below (tomogram 010).

Examples of reconstructed tomograms of cross sections of torches, in different sections and arc shown in the photographs are placed below (tomogram № 200, № 168):