Canadian Patents & Development Ltd.

National Research Council of Canada

Canadian Patents and Development Limited/societe Canadienne Des Brevets

Her Majesty the Queen As Represented by the Minister of National Defence

Paolo G Cielo

Mario Lamontagne

Ghislain Vaudreuil

Mohamad Sabsabi

Marc Dufour

Kenneth C Cole

Serge Dallaire

Christian Moreau

Jean F Bussiere

Michel M Dumoulin

Louis St-Onge

Jacques Guevremont

Jean-Claude Krapez

Xavier Maldague

Jean C Krapez

Gerard Rousset

A method and apparatus is disclosed for enhanced laser-induced plasma spectroscopic analysis of unknown heterogeneous materials. The apparatus has high power pulsed lasers with their beams focused on the material, typically two colinear lasers providing two pulses in the ultraviolet and in the near infrared spectral area. The first laser pulse vaporizes a small volume at the surface of the material and produces a plasma which is subsequently enhanced by the second laser pulse. The optical emission of the plasma is analyzed with a colinear optical spectrometer. The pulsed spectrum is detected by a gated photodiode array detector or by an array of photomultipliers each individually positioned to detect a line emission representative of a given element present in the material. The combination of the two laser pulses, appropriately synchronized, provides a plasma emission that is significantly stronger than a single laser pulse of the combined energy of the two pulses.

Method and apparatus for materials analysis by enhanced laser induced

A method and apparatus for rapid in-situ spectroscopic analysis of unknown heterogeneous materials is disclosed. The apparatus uses a high power pulsed laser whose beam is focused on the material, typically a porous compound of unknown composition such as an amalgamated powder or a mineral sample. The pulsed laser beam vaporizes a small volume of the material and produces a plasma having an elemental composition which is representative of the material composition. The optical emission of the plasma is analyzed with an optical spectrometer. The pulsed spectrum is detected by a gated photodiode array detector or by an array of individually positioned photomultipliers, to detect a background emission and a line emission representative of a given element present in the material. Because such measurements may fluctuate considerably for porous materials due to unpredictable variations of the plasma temperature and the amount of vaporized mass, the signals are normalized by establishing a ratio of the intensity of the signals to that of the background plasma emission.

Method and apparatus for spectroscopic analysis of heterogeneous

A method and apparatus for determining surface molecular orientation and related properties of an opaque polymeric sheet relies on the detection of relative intensity of spectral reflectance in at least one polarized beam reflected from the surface of the sheet rather than transmitted therethrough. The relative intensity is affected by the preferential orientation of the polymeric chains. The method is fast and can be applied on-line at a speed of the running sheet as high as 1000 m/s.

Method and device for evaluation of surface properties, especially

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. The time delay between these two peaks may be evaluated automatically and the particle velocity computed knowing the distance between the two slit images.

Method and apparatus for monitoring the temperature and velocity of

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.

Method and apparatus for monitoring the surface profile of a moving

Apparatus for nondestructive detection of subsurface defects in a continuously moving workpiece of sheet material by using an infrared thermal imager. The temperature of a portion of the surface of sheet material is altered and the presence of subsurface flaws is indicated by development of discontinuities in the surface temperature distribution above the defects. In order to avoid problems due to changes in the infrared emissivity of the surface of sheet material, such as caused by grease patches or oxidized areas as well as errors caused by reflections of other sources of infrared radiation from the surface, the thermal image of the portion is first transferred by contact to a surface of a thermal transfer device whose surface has a high infrared emissivity and a low infrared reflectivity. Then the thermal image of the portion is obtained from the surface of the thermal transfer device.

Device for subsurface flaw detection in reflective materials by thermal

The present disclosure describes an apparatus and a method for detecting the presence of flaws in a moving sheet of material. The apparatus comprises a light source for projecting a light beam; a beam shaping unit for shaping the light beam into a predetermined structured light pattern, and projecting the structured light pattern onto a portion of the surface of the sheet; an optical unit for collecting light emitted from the portion of the surface; and a light detecting unit for receiving the light collected by the optical unit and generating an electrical signal indicative of the intensity of the light generated from the portion of the surface. A signal processing unit is provided for filtering the electrical signal, the signal processing unit having predetermined characteristics specifically adapted to match an expected electrical signal corresponding to the predetermined structured light pattern. The present invention can be used in a transmission mode wherein the light beam is projected onto one side of the moving sheet and detected from the opposite side, or in a reflective mode wherein the light beam is projected onto and detected from the same side of the moving sheet.

Method and apparatus for detecting the presence of flaws in a moving

The degree of cure in a polymeric composite is evaluated in a simple, rapid and non-destructive manner by heating a surface portion of the polymeric composite to substantially curing temperature, over a predetermined period of time, and continuously monitoring with a non-contact temperature sensor temperature fluctuations of the heated surface portion during the predetermined period of time to obtain data comprising surface temperature values measured as a function of time. By processing such data including comparing with a calibration reference, for example by providing a curve of the measured surface temperature values against time and comparing with a reference curve, one can evaluate the degree of cure of the polymeric composite.

Method and apparatus for evaluating the degree of cure in polymeric

A method for the detection of delaminated areas in coated materials or layered composites, which allows free-air operation and can be used to scan portions of bulky materials on the spot. This method which makes it possible to detect very small delaminated areas in a very short time (less than 1 millisecond), with a very high sensitivity and without creation of excessive thermal stress in the inspected material, basically comprises the steps of: focusing pulsed, thermal radiations onto the structure to be inspected to produce a vertical displacement of its coating by thermal expansion if a delaminated area is present at the coating-to-substrate interface, and detecting and measuring this vertical displacement if any, by interferometry, preferably laser-beam interferometry. An apparatus for carrying out this method is also disclosed.

Pulsed dilatometric method and device for the detection of delaminations

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.

Method for on-line thickness monitoring of a transparent film

An apparatus using optical techniques for simultaneously detecting surface defects and measuring the diameter of a wire coming out from an extruder. A combination of cylindrical lenses is used for projecting, perpendicularly across the longitudinal axis of the wire, a sharply focused laminar beam. This apparatus includes an optical source system for emitting optical rays, an optical system for focusing the rays on the wire, an optical detector system for receiving the rays and generating a detector signal to be processed by a signal processing system, the processing system generates an electric signal indicative of the amplitude of the defects and another electric signal indicative of the diameter of the wire.

Optical device for measuring the diameter and detecting surface defects

The surface acoustic waves are generated by laser beam that is focussed onto a surface to irradiate it in an arcuate pattern as a partial annulus or as a still or moving fringe pattern. The arcuate pattern may be formed by a transmitting or a reflecting axicon, while the fringe pattern may be formed by splitting the laser beam into two beams and directing the two beams to the surface. In addition, a lens or a frequency shifting device may be placed in the path of one of the split beams to form a circular fringe or a moving fringe, respectively.

Efficient laser generation of surface acoustic waves

The apparatus for analyzing the surface of a fibrous web, such as a paper or a textile, includes a prism structure in which one surface is placed in contact with the fibrous web under a predetermined pressure. A collimated beam of light is directed into the prism on the contact surface. The light reflected from the contact surface through the prism is directed to a detector. The detector senses the light reflected by the contact surface as well as the light diffracted at the contact surface to indicate the surface condition of the fibrous web.

Optical system for analyzing the surface of a fibrous web

The laser-surface coupler is used to uniformly irradiate a well defined surface area with a laser beam. The coupler includes a lower masking section and an upper section to form a cavity. The masking section has inner surfaces which are highly reflective and lustrous, and an aperture to define the surface area to be irradiated. The upper section has an opening to receive the laser beam into the cavity, and a highly reflective and diffuse inner surface to reflect and diffuse any radiation reflected to it from the irradiated surface. The coupler recycles any reflected radiation from the laser beam increasing the absorption coefficient and the irradiated surface is precisely defined by the masking section without loss of energy.

Laser-surface coupler

A tunable optical fiber reflector is described, together with a method of making the same. A length of optical fiber has a core of a first light transmitting material, and a cladding of a second light transmitting material covering the core. The cladding is etched away to a predetermined thickness over a portion of the fiber. A layer of photoresist material is applied either to the etched away portion of the fiber or to a thin metal blade, i.e., mask, and then exposed to beams of light which optically interfere and generate a standing wave pattern in said material. The photoresist material is then developed to fix said wave pattern therein. An optical discontinuity is formed in one of the core and cladding by that fixed wave pattern, said discontinuity representing a quasi-periodical fluctuation in the refractive index and causing evanescent waves in the cladding to be reflected. Such discontinuity forms a distributed-feedback reflector. In one method, the fiber core in the etched portion is bombarded under a vacuum with a beam of ions passed through openings having said standing wave pattern, thus producing quasi-periodical fluctuations in the refractive index of the core. More preferably, the photoresist material is coated on the etched portion of the fiber, and counter-propagating light beams are coupled into opposite ends of the fiber. These beams expose the photoresist material and generate the standing wave pattern therein as residual quantities of the same. The etched portion of fiber is typically filled with reinforcing material such as an epoxy. Two such reflectors in an optical fiber make up a resonator, and several resonators can be used in a hydrophone line-array.

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Montreal, Canada

Paolo G Cielo