Institut National D'optique

Leddartech Inc.

Other

Exfo Electro-optical Engineering, Inc.

François Babin

Daniel Cantin

Marc Levesque

Pascal Gallant

Marc Lévesque

Jean-François Gravel

Yvan Mimeault

Gang He

Pascal Dufour

Hongxin Chen

Daniel Gariépy

The method for determining the presence of a molecule having a Raman resonance generally comprises illuminating a sample with a first radiation beam, the first radiation beam having a first excitation wavelength being tuned to a Raman resonance of the molecule; receiving a first return signal from the sample following illumination of the sample with the first radiation beam; measuring a first intensity of the first return signal using an intensity detector; illuminating the sample with a second radiation beam, the second radiation beam lacking the first excitation wavelength and having a second excitation wavelength being different from the first excitation wavelength; receiving a second return signal from the sample following illumination of the sample with the second radiation beam; measuring a second intensity of the second return signal using an intensity detector; and determining the presence of the molecule in the sample based on the first and second intensities.

Methods and systems for determining the presence of a molecule in a sample and method and system for determining a range-resolved concentration of a molecule in a scene

The method of determining the presence of a spill of a petroleum product by the detection of a petroleum-derived volatile organic compound (VOC) generally has a step of providing an ultraviolet (UV) radiation generator and a receiver assembly aimed at a scene; a step of illuminating a distant target in the scene with a UV radiation beam, the UV radiation beam having an excitation wavelength being tuned to a resonance Raman excitation wavelength of the petroleum derived VOC; a step of receiving a return signal from the distant target; and a step of determining the presence of the petroleum-derived VOC upon detecting Raman scattering in the received return signal, the Raman scattering being indicative of a resonance Raman interaction between the UV radiation beam and molecules of the petroleum-derived VOC.

Method and device for determining the presence of a spill of a petroleum product by the detection of a petroleum-derived volatile organic compound

There is described a method for remotely monitoring an exhaust plume emitted by an exhaust stack, the method comprising: determining a velocity of a flow of the exhaust plume at an output of the exhaust stack, the exhaust plume comprising one molecule; propagating a first light within the exhaust plume, the first light being propagated in close proximity to the output of the exhaust stack; detecting a second light emitted by the exhaust plume and measuring an energy of the second light, the second light resulting from an interaction of the first light with the exhaust plume; and determining a mass emission rate of the at least one molecule using the measured energy of the detected second light, the velocity, and a surface area of the exhaust plume at the output of the exhaust stack, the surface area being orthogonal to a direction of the flow of the exhaust plume.

Method and system for monitoring emissions from an exhaust stack

An optical system for sensing an environmental parameter, comprising: an optical pulse generator for generating an excitation pulse; a pulse splitter for splitting the excitation pulse into a sensing pulse and a reference pulse; a sensing arm for receiving the sensing pulse, the sensing arm comprising an emission sensor for sensing the environmental parameter, the optical emission sensor generating a first measurement pulse having a measurement wavelength; a reference arm for receiving the reference pulse, the reference arm comprising an emission artifact adapted to convert the reference pulse into a second measurement pulse having the measurement wavelength; a time delay line for delaying a relative propagation of the measurement pulses; a light detector for measuring an optical energy of the first and second measurement pulses; and an optical link for optically connecting the pulse generator to the pulse splitter, and the sensing and reference arms to the light detector.

Optical method and system for measuring an environmental parameter

An optical system for sensing an environmental parameter, comprising: a pulse generator for generating a first pulse having a first wavelength and a second pulse having a second wavelength; a pulse splitter for splitting each one of the first and second pulse into a sensing pulse and a reference pulse; a sensing arm for receiving the sensing pulses therefrom and comprising a spectro-ratiometric sensor; a reference arm for receiving the reference pulses; a time delay line for delaying a relative propagation of the sensing pulses and the reference pulses; a light detector for measuring an optical energy of the sensing pulse and the reference pulse, for the first and second wavelengths; and at least one optical link for optically connecting the pulse generator to the pulse splitter, and the sensing and reference arms to the light detector.

A method for detecting an object using light comprises providing a light source having a function of illuminating an environment. The light source is driven to emit light in a predetermined mode, with light in the predetermined mode being emitted such that the light source maintains said function of illuminating an environment. A reflection/backscatter of the emitted light is received from an object. The reflection/backscatter is filtered over a selected wavelength range as a function of a desired range of detection from the light source to obtain a light input. The presence or position of the object is identified with the desired range of detection as a function of the light input and of the predetermined mode.

Method for detecting objects with light

A method for detecting an object using visible light comprises providing a visible-light source having a function of illuminating an environment. The visible-light source is driven to emit visible light in a predetermined mode, with visible light in the predetermined mode being emitted such that the light source maintains said function of illuminating an environment. A reflection/backscatter of the emitted visible light is received from an object. The reflection/backscatter is filtered over a selected wavelength range as a function of a desired range of detection from the light source to obtain a light input. The presence or position of the object is identified with the desired range of detection as a function of the light input and of the predetermined mode.

Method for detecting objects with visible light

Methods and apparatuses for reducing the response time along with increasing the probability of ranging of optical rangefinders that digitize the signal waveforms obtained from the pulse echoes returned from various types of objects to be ranged, the pulse echoes being too weak to allow successful ranging from a single waveform or the objects being possibly in motion during the capture of the pulse echoes. In a first embodiment of the invention, the response time at close range of a digital optical rangefinder is reduced by using a signal averaging process wherein the number of data to be averaged varies with the distance according to a predetermined function. In a second embodiment of the invention, the probability of ranging objects in motion along the line of sight of a digital optical rangefinder is increased and the object velocity measured by performing a range shift of each acquired signal waveform prior to averaging. In a third embodiment of the invention, the signal waveforms acquired in the line of sight of a digital optical rangefinder are scanned over a predetermined zone and range shifted and averaged to allow for early detection and ranging of objects that enter in the zone.

Digital signal processing in optical systems used for ranging applications

A method and apparatus provide for non-contact optical measurement of the level of a fluid stored in a tank or container, the surface of the fluid being possibly agitated. The method processes numerically the digitized signal waveforms generated by a lidar apparatus based on a pulsed time-of-flight modulation scheme. A key step of the numerical processing is the computation of a waveform in which each data point is obtained from a statistical estimator of the variability of the amplitude signal echo measured at the distance from the lidar apparatus that corresponds to the rank of the data point in the waveform. The statistical estimator is preferably the standard deviation. By using a statistical estimator of the variability of the captured signal amplitude, the specific signal echo returned from an agitated fluid surface can be greatly amplified as compared to the signal echoes returned from any obstacle or medium that could be present along the path of the optical beam radiated by the lidar apparatus. The method then allows for an efficient retrieval of the useful signal echo from which the level of the fluid surface can be reliably measured with greater accuracy, particularly in situations where the useful signal echo would be buried in a strong signal echo returned from any optically scattering or absorbing medium that would fill in the volume of the tank above the fluid surface.

Method and apparatus for optical level sensing of agitated fluid surfaces

A rangefinding device and a method for determining the range of an object from a rangefinding device are provided. A train of light pulses each having an emission time and a pulse duration is generated. The pulse duration is set to twice the round-trip time to a maximum range of the device. The light pulses are reflected back toward the device by the object and detected according to three time intervals, respectively determined by a background gate, a ranging gate and a pulse energy gate. The light energy received during each interval is integrated and the integrated light value corresponding to the ranging gate is normalized using the values from the other two intervals. The range of the object is determined from the normalized ranging measurement and calibration data.

Light-integrating rangefinding device and method

An optical system for measuring in real-time the spatial distribution of aerosol particles, such as pesticides or the like, sprayed from a vehicle over an agricultural field. An optical sensor is mounted directly on the vehicle and sends an excitation light beam through the aerosol as it is being sprayed. The resulting scattered light is received and analyzed to deduce therefrom information on the spatial distribution of the particles. This information is relayed to a processing unit, which in turn provides spraying instructions, for example a warning signal, to the operator of the system. The spraying of the aerosol can therefore be controlled in real-time to avoid contamination of sensitive areas.

Real-time measuring of the spatial distribution of sprayed aerosol particles

A widely-tunable laser apparatus comprises a plurality of tunable lasers having different ranges that overlap to encompass a desired operating range of wavelengths (for example from 1250 nm to 1650 nm) of the widely-tunable laser apparatus. The tunable lasers are tunable synchronously and selectively with their respective outputs connected in common to sweep the output of the widely-tunable laser apparatus substantially continuously over said operating range. The tunable lasers share the same tuning means which has a plurality of independent channels, each for light from a respective one of the tunable lasers.

Widely-tunable laser apparatus

A flat spatial response LIDAR apparatus for detecting particles within a short range is provided. The apparatus includes a light source projecting a light beam which is back-scattered by the particles to be detected. The back-scattered light is received, detected and analyzed. A spatial filter spatially filters the received back-scattered light in order to flatten the spatial response of the apparatus, so that a same concentration of particles at any distance within the short range will generate a signal of substantially the same intensity. This is for example accomplished by a properly profiled mask disposed in front of the detector, or a plurality of spatially distributed waveguides. As a result, the LIDAR apparatus can compensate for the 1/rdependence, or other dependences of the back-scattered light on the distance r.

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Québec, Canada

François Babin