The focused laser radiation is widely used in technological processes for cutting and welding of various materials, engraving; in scientific researches at an interaction of radiation with matter, for definition of radiation quality and its divergence; in medicine for the local biological objects irradiation. A scanning narrow slit and knife-edge [l], a scanning small hole with a thin metal tubule as a light-guide [2], a photodiode or pyroelectric receivers matrix [3] are used for measuring of focal spot parameters of the continuous laser radiation. In the first two expedients there are technical difficulties with registration of passed radiation, and in last two there is not a high spatial resolution on coordinate.The mentioned shortcomings of the known measuring methods it is possible to diminish by using the scanning thin-wire bolometer with a diameter in unities of micrometers, possessing a high coordinate resolution, having possibility to operate in a wide spectral range and withstanding high densities of laser radiation intensity. The aim of this paper consists in experimental confirmation of the micrometer diameters measuring possibility of the focused laser radiation by thin-wire bolometers.The bolometer material was selected platinum, which does not yielld to corrosion in a wide temperature interval, has melting point 1769OC and has smoothly temperature dependences of basic physical parameters (temperature coefficient of resislance, factor of absorption efficiency, specific heat, thermal conductivity and coefficient of heat exchange with environment), which determine a transformation coefficient of the bolometer. The thin-wire platinum bolometer had the diameter 3 microns and length 8,4 mm.The monomode laser JITH-302 with a wavelength 0,63 p generating on two stabilized close frequencies with a mutually perpendicular direction of linear polarizations was used as radiation source. Either linear polarizations of radiation it was possible to pick by polarizers. The output power of radiation was simultaneously stabilised with frequency. The diameter of an output laser radiation was about 1 mm.The flowchart of experimental set is shown in fig. 1. The focusing device is an achromatic lens of a microscope with a focal length 6,O mm. The working bolometer Rb and compensation one Rbc are practically identical, and were disposed on a termazote plate with hole3 and were mechanically fastened on the electromagnetic device, which shift was ensured by feeding of a tooth voltage from the generator r6-28. Velocity and uniformity of its shift were beforehand determined by a microscope and stroke length measures. The shift of the working bolometer was in cross-section of an optical beam. After the focusing device the optical radiation was coming into an air chamber preventing essential nonregular airflows and diminishing of the bolometer heat exchange fluctuations with an environment.The change of the bolometer resistance was registered by a bridge circuit consisting of resistances Rb, hc, RI and R2. In operating conditio...
