RGB color camera for dynamical measurements of high temperature distribution on a surface of the heated solid

In this report we describe a fast 3-color method of the measurement of temperature distributions on a surface of a heated solid using a RGB color camera with a high frame rate (100 images per second). Statistical error the RGB method is not high, and do not exceed around 5.5 % which is surprising taking in to account the number of the measurements at each pixel. Comparison of the results of the temperature measurements on a tungsten plate heated by infra-red laser radiation and conducted with this technique and those obtained with the acousto-optical tunable filter technique demonstrate that error of the temperature measured by 3-color method is only two times as high as that of the tandem acousto-optic filter technique method.This work was performed using the Unique Scientific Instrument 'Laser heating at diamond anvil cell'[http://ckp-rf.ru/usu/507563/]

Multi-spectral image processing for the measurement of a spatial temperature distribution on the surface of a laser-heated microscopic object

In this paper, we demonstrate that combining a laser heating (LH) system with a tandem acousto-optical tunable filter (TAOTF) allows us to measure the temperature distribution (TD) across a laser-heated microscopic specimen. Spectral image processing is based on one-dimensional (1D) non-linear least squares fitting of the Planck radiation function. It is applied for determining the temperature T at each point (x, y) of the specimen surface. It is shown that spectral image processing using the 1D non-linear least squares fitting allows measurement of the TD of the laser-heated microscopic specimen with higher precision and stability than those of the conventional linear least-squares fitting of the Wien approximation of Planck’s law.The Russian Science Foundation (project #17-12-01535) financially supported the work

Superhard Phases of Simple Substances and Binary Compounds of the B-C-N-O System: from Diamond to the Latest Results (a Review)

The basic known and hypothetic one- and two-element phases of the B-C-N-O system (both superhard phases having diamond and boron structures and precursors to synthesize them) are described. The attention has been given to the structure, basic mechanical properties, and methods to identify and characterize the materials. For some phases that have been recently described in the literature the synthesis conditions at high pressures and temperatures are indicated.Comment: Review on superhard B-C-N-O phase

Measurement of the Elastic Properties of Solids by Brillouin Spectroscopy

Brillouin Light Scattering (BLS) is a non-contact measurement technique that exploits light scattering to probe the properties of ultrasonic waves, either bulk waves propagating in transparent solids or liquids, or surface acoustic waves (SAWs) propagating at the surface of homogeneous solids or of thin layers, either supported or free standing. In BLS the scattering geometry selects a specific wavevector and probes the ‘thermal noise’ at that wavevector, therefore performing a sampling of the dispersion relation of waves. This is done by illuminating the surface with a laser beam and examining the spectrum of the scattered light.. From the spectrum of the ‘inelastically’ scattered light and the scattering geometry, one can derive the dispersion relation for the ultrasonic waves, and then infer the elastic properties of the material. How this is done is the subject matter of this chapter. The light scattering nature of BLS measurements has three main consequences. First, mechanical contact with the sample is not needed: only optical access is required. Second, scattering occurs locally, in a volume of the order of tens of micrometers. Third, in BLS it is the acoustic wavelength that is determined by the experimental conditions. With visible light the explored acoustic wavelengths are sub-micrometric, meaning that with typical surface and bulk acoustic modes the probed frequencies range from a few GHz up to several tens of GHz. Such small wavelengths give a peculiar sensitivity to thin and ultra-thin. Brillouin scattering techniques also have drawbacks. First, thermally excited fluctuations have small amplitude, requiring time consuming measurements; second, the probed wavelengths are small and span a limited range. Therefore, Brillouin scattering techniques are the preferred technique for materials such as thin films and whenever the contactless nature of measurements makes BLS the only, or almost the only, available choice, as it happens in extreme conditions like thye diamond anvil cell. This chapter is a review of the application of BLS for the evaluation of the elastic properties of materials in the above two main areas—thin coatings and solids under extreme conditions. It should be mentioned that BLS is also actively exploited for the characterization of magnetic materials through the detection of magnons or spin waves. However, this is a different field that deserves a review by itself and will not be considered here

RGB color camera for dynamical measurements of high temperature distribution on a surface of the heated solid

In this report we describe a fast 3-color method of the measurement of temperature distributions on a surface of a heated solid using a RGB color camera with a high frame rate (100 images per second). Statistical error the RGB method is not high, and do not exceed around 5.5% which is surprising taking in to account the number of the measurements at each pixel. Comparison of the results of the temperature measurements on a tungsten plate heated by infra-red laser radiation and conducted with this technique and those obtained with the acousto-optical tunable filter technique demonstrate that error of the temperature measured by 3-color method is only two times as high as that of the tandem acousto-optic filter technique method