Abstract: An apparatus for use in solidification of a doped electrically conducting material and for use in monitoring said solidification is provided. The apparatus includes a first forming means for forming a liquid of undoped material in thermodynamic equilibrium with a solid of the undoped material, and a second forming means for forming a liquid of doped material in thermodynamic equilibrium with a solid of the doped material. Solidification of the conducting material occurs at a solidification interface between the doped liquid and the doped solid in the second forming means. In one preferred embodiment, the apparatus comprises a conductive bridge for short-circuiting the liquids.

Abstract: The present invention relates to a process and an apparatus for checking the supercooling of a monocrystal during its formation.There is a continuous measurement of the potential difference between one point of the forming crystal and one point of a solid part of the material separated from the liquid by a reference interface differing from the solidification front. This potential difference makes is possible to determine the temperature deviation due to the supercooling at the solidification front and the dopant concentration of the crystal being formed.

Abstract: The laser comprises an amplifying medium placed between a first reflector and a second dispersive reflector, and a rotating wheel adapted to carry a plurality of optical deflector elements interposed between the amplifying medium and the second dispersive reflector. A light beam having a certain incidence only in respect of a predetermined wavelength which is dependent on the incidence is reflected backwards from the second dispersive reflector. The optical reflector elements are placed periodically in the path of the light beam so as to produce a sequential modification in the incidence of the light beam emerging from the amplifying medium and to give the incidence a number of different values corresponding to the desired number of wavelengths.