Abstract: In a method of measuring the thickness of a coating as it is applied to a substrate, wherein the coating is applied as a thin ribbon from a spray gun, at least one surface profile of the applied coating is obtained along a line intersecting the ribbon during relative movement of the substrate and spray gun. The thickness of the applied coating is computed from the obtained surface profile.

Abstract: In a method of measuring the thickness of a coating as it is applied to a substrate, wherein the coating is applied as a thin ribbon from a spray gun, at least one surface profile of the applied coating is obtained along a line intersecting the ribbon during relative movement of the substrate and spray gun. The thickness of the applied coating is computed from the obtained surface profile.

Abstract: A method and an apparatus for monitoring simultaneously the temperature and velocity of a thermal spray jet. The apparatus has a sensor head directed at the jet, the sensor head having two optical fibers carrying radiation from the jet to a remote detection unit which comprises two or three photodetectors. The radiation carried by the separate optical fibers is filtered at two different wavelengths before being passed to the photodetectors. The temperature of the jet is determined by analyzing the ratio of the energy radiated at the two wavelengths. The velocity of the jet is determined, knowing the distance between the fibers, by measuring the time delay between the signals carried by the separate fibers using cross-correlation.

Abstract: In a method of monitoring in-flight particles, a mask in a is placed in a plane generally parallel to the direction of travel of the particles. The mask defines at least two slits that are generally parallel and lie in a direction having at least a component at right angles to the direction of travel. The slits have their ends offset relative to each other. The slits radiation emitted, scattered or absorbed by the particles is monitored as they traverse the slits field of view. The particles for which the radiation, emitted, scattered or absorbed which is collected through each slit as they sequentially traverse said slits bears a predetermined relationship are identified, and the size of the identified particles is determined from the amount of radiation emitted, scattered or absorbed as the identified particles traverse the slits.

Abstract: A method and an apparatus for monitoring simultaneously the temperature and the velocity of sprayed particles. The system is comprised of a sensor head attached to the spray gun, an optical fibre transmitting the collected radiation to detection apparatus, and a protective detection cabinet having the detection apparatus that incorporates two detectors. A two-slit or multiple-slit mask is located in the sensor head at the end of the optical fibre. For the temperature measurements, the particle emitted radiation collected by the sensor head is transmitted to two photodetectors, filtered by interference filters at two adjacent wavelengths. The particle temperature may be computed from the ratio of the detector outputs. To measure the velocity, the two-slit system collects radiation emitted by the in-flight particles travelling in the sensor field of view, which generates a double peak light pulse transmitted through the optical fibre.

Abstract: An optical inspecting apparatus and the method thereof, including a series of optical units for rapidly acquiring the three-dimensional surface profile of a moving object. Each optical unit contains a multiple-beam light source to project a number of luminous spots on the object surface which are imaged through a properly oriented line-array camera. The surface position on both sides of the object, and thus the object thickness, is inferred at the position of each luminous spot from an analysis of their camera image. The projected luminous spots are preferably elliptically shaped and the line array elements are elongated in a direction perpendicular to their longitudinal axis in order to reduce speckle and other optical noise. The described optical configuration results in a superior performance in terms of spatial resolution and response speed.

Abstract: An optical system is described for monitoring the thickness of a translucent film either free-standing or coated on a reflective substrate. A polychromatic light beam is projected onto the surface of the sheet, and the transmitted light is detected at, at least, three wavelengths of which only one corresponds to an absorption band of the film material. By properly processing the three or more detected signals, an accurate evaluation of the film thickness is obtained irrespective of the presence of colored pigments in the material or of wavelength-dependent attenuation due to scattering at the film interfaces. Optical configurations are also described which avoid errors produced by interference fringes or front-surface reflections while simplifying the scanning of the sheet surface.