No abstract

The diffusion layer thickness, 8, was measured as a function of time by a Mach-Zehnder interferometer on a vertical cathode in CuSO4 solution with and without an excess of H2SO4 at current densities, i, up to 100 nlA/cm ~. The thickness 6 increased linearly with t I/2 up to the start of hydrogen gas evolution in CuSO4 solutions with and without H2SO4; in the presence of tenfold excess of H2SO4, 5 rapidly increased just before the gas evolution. At a constant cathodic charge, log 5 decreased linearly with increasing log i in both solutions and 6 is larger in pure CuSO4 solution than in the presence of excess of H2SO4.

No abstract

A Lloyd mirror laser interferometer is described which determines the refractive index gradient in a diffusion layer. The interference fringe movement is detected by an array of n-p-n planar silicon photodevices the output of which is recorded by oscillographs. Various modes of measurement are discussed which are suitable for transparent or opaque electrodes. The presently used measuring mode is based on the determination of the reflected ray's optical path length change at various angles of incidence. The refractive index gradient is obtained by an iterative solution of the derived equation for the optical path length change on a digital computer. The time dependence of the fringe movement during electrodeposition from CuSO4 solutions is discussed in addition to the effect of incidence angle and cathode displacement. The use of this interferometer is not limited to electrochemical processes and it can be used for the study of refractive index gradients in heat and other mass transfer boundary layers at solids.

The forward scattering of light by an optical fiber produces an interference fringe pattern, and the fringe period is inversely proportional to the fiber diameter. An electrooptic system has been developed to produce and detect this scattering pattern to provide an instrument which will measure fiber diameter during the drawing operation. The system measures the fiber diameter at a 1-kHz rate with a precision of 0.25 microm and an accuracy of +/-0.25 microm over a range of 50-150-microm diams. The instrument allows the fiber to move laterally in a 1-cm diam window maintaining the above accuracy. The system can be calibrated optically and does not need a standard fiber for this procedure. The instrument has been used for months without the need for recalibration. In addition to the digital diameter output, the system employs a microprocessor to compute mean and standard deviation values for various sample lengths and provides suitable signals for feedback control of fiber diameter.