Patent Description:
Soil tests are generally performed in a laboratory. From a practical point of view, several soil samples are typically extracted from a field under investigation, before being sent to the laboratory for subsequent analyses and characterization.

However, the different characteristics of the soil samples are known to change over time, which may occur during their transport or when they are stored. Thus, the results of the analyses performed on such altered soil samples may not be representative of the soil characteristics. The characteristics of the soil also vary over space, within the same field. As laboratory characterizations are time consuming and also generally expensive, only one laboratory analysis is traditionally performed per field, resulting in a relatively poor characterization of the field. A conventional device for measuring reflectance and fluorescence of in-situ soil is disclosed in <CIT>, in which a soil penetrating probe is fitted with a light transparent window on one side and with a light source disposed internally of the probe; light from the light source passes through the window in the probe and irradiates soil passing past the window as the probe is advanced into the soil; light reflected back through the window from the irradiated soil is collected by a fibre optic link disposed within the probe. In addition, <CIT> discloses a conventional specular integrating tube for scattered-light spectroscopy.

There is thus a need for a system, device, as well as methods that address or alleviate at least some of the challenges presented above.

In accordance with one aspect, there is provided an optical probe for analysing a soil located in an underground area as defined in claim <NUM>. The optical probe includes a probe head insertable into the underground area to contact the soil, the probe head including a transparent wall defining a hollow chamber within the probe head, the transparent wall having a top extremity and a bottom extremity defining an optical path therebetween; a light source mounted in the hollow chamber, the light source being configured to generate an illumination beam towards the soil, the illumination beam passing through the transparent wall to irradiate the soil, thereby producing a resulting light emanating from the soil, a portion of the resulting light returning towards the probe head and being guided in the transparent wall by total internal reflection along the optical path; a detector configured to receive the portion of the resulting light guided in the transparent wall and outputting an output signal representative of at least one characteristic of the soil; and an optical element mounted in the hollow chamber, near or at the top extremity of the transparent wall, the optical element guiding the portion of the resulting light guided in the transparent wall from the transparent wall to the detector.

In some embodiments, the light source includes a light-emitting diode configured to emit the illumination beam, the illumination beam having a spectral profile including a waveband ranging from about <NUM> to about <NUM>.

In some embodiments, the spectral profile includes a visible waveband ranging from about <NUM> to about <NUM>.

In some embodiments, the optical probe further includes a first radial lens optically coupled to the light-emitting diode for generating a collimated illuminating beam.

In some embodiments, the first radial lens is positioned at or near the bottom extremity, in the hollow chamber.

In some embodiments, the light source includes a stack of light-emitting diodes.

In some embodiments, the stack of light-emitting diodes including a white broad band light-emitting diode.

In some embodiments, the stack of light-emitting diodes includes an infrared broad band light-emitting diode.

In some embodiments, the stack of light-emitting diodes includes a blue-light emitting diode.

In some embodiments, the stack of light-emitting diodes includes an ultra-violet light-emitting diode.

In some embodiments, the stack of light-emitting diodes includes an ultra-violet light-emitting diode emitting an ultra-violet sub-beam having a spectral profile including a waveband centered around <NUM>; a blue light-emitting diode mounted on the ultra-violet light emitting diode and emitting a blue sub-beam having a spectral profile including a waveband centered around <NUM>; an infrared broad band light-emitting diode mounted on the blue-light emitting diode and emitting an infrared sub-beam having a spectral profile including a waveband ranging from about <NUM> to about <NUM>; and a white broad band light-emitting diode mounted on the infrared broad band light-emitting diode and emitting a white sub-beam having a spectral profile including a waveband ranging from about <NUM> to about <NUM>.

In some embodiments, each light-emitting diode from the stack of light-emitting diodes is optically coupled with a respective radial lens.

In some embodiments, the portion of the resulting light guided by the transparent wall includes light scattered by the soil.

In some embodiments, the portion of the resulting light guided by the transparent wall includes light reflected by the soil.

In some embodiments, the transparent is tubular and the light source is configured to irradiate the soil through <NUM> degrees around the probe head.

In some embodiments, the transparent wall is made from a material impermeable to a soil solution present in the soil.

In some embodiments, the transparent wall is made of clear fused quartz.

In some embodiments, the transparent wall is made of sapphire.

In some embodiments, the optical element includes an optical diffuser positioned near or at the top extremity, in the hollow chamber, the optical diffuser being optically coupled with the transparent wall for scattering the portion of the resulting light guided in the transparent wall inside the probe head.

In some embodiments, the optical probe further includes a second radial lens for focusing the light scattered by the optical diffuser towards the detector, the second radial lens being optically coupled with the optical diffuser.

In some embodiments, the second radial lens is mounted in the hollow chamber.

In some embodiments, the optical probe further includes an optical fiber located near or at the top extremity, the optical fiber guiding the portion of the resulting light guided in the transparent wall towards the detector.

In some embodiments, the optical fiber is in mechanical contact with the transparent wall.

In some embodiments, the detector is a spectrometer
In some embodiments, the hollow chamber encloses the detector.

In some embodiments, the optical probe further includes a processor, the processor being configured to receive the output signal representative of said at least one characteristic of the soil; and determine a spectral content of the portion of the resulting light guided by the transparent wall
In some embodiments, the optical probe further includes a control unit operatively connected to at least one of the light source and the detector, the control unit being configured for operating and controlling said at least one of the light source and the detector.

In some embodiments, said at least one characteristic of the soil are selected from the group consisting of: level of nutrients, level of available nutrients, ionic concentration of the soil solution, temperature, moisture, pH, level of organic matter and soil texture.

In some embodiments, the optical probe further includes a power unit including at least one battery.

In some embodiments, the at least one battery has an autonomy of about <NUM> measurements.

In some embodiments, the optical probe further includes a sensing tip mounted at an extremity of the probe head, the sensing tip being configured to measure at least one of the electroconductivity and the pH of the soil.

In some embodiments, the optical probe further includes a body having a bottom end portion, the probe head being mounted to the bottom end portion.

In some embodiments, the body has a height ranging from about <NUM> to about <NUM> and the probe head has a height ranging from about <NUM> to about <NUM>.

In some embodiments, the probe head has an outer surface area ranging from about <NUM><NUM> to about <NUM><NUM>.

In accordance with another aspect, there is provided a method for analysing a soil located in an underground area as defined in claim <NUM>. The method includes steps of inserting a probe head in the underground area to contact the soil, the probe head including a transparent wall defining a hollow chamber within the probe head, the transparent wall having a top extremity and a bottom extremity defining an optical path therebetween; projecting an illuminating beam towards the soil and through the transparent wall to irradiate the soil, thereby producing a resulting light emanating from the soil and returning towards the probe head; guiding, in the transparent wall, a portion of the resulting light by total internal reflection along the optical path; guiding, with an optical element, the portion of the resulting light guided in the transparent wall with an optical element from the transparent wall to a detector; detecting the portion of the resulting light guided in the transparent wall; and outputting an output signal representative of the at least one characteristic of the soil.

In some embodiments, the method further includes processing the output signal representative of said at least one characteristic of the soil.

In some embodiments, said processing the output signal representative of said at least one characteristic of the soil includes: receiving the output signal representative of said at least one characteristic of the soil; and determining a spectral content of the portion of the resulting light guided in the transparent wall.

In some embodiments, the method further includes measuring at least one of the electroconductivity and the pH of the soil with a sensing tip mounted at an extremity of the probe head.

In some embodiments, the method further includes wirelessly operating and controlling at least one of the light source and the detector.

In some embodiments, further includes drilling a hole in the underground area to receive the probe head therein.

In some embodiments, said inserting the probe head in the underground area to contact the soil includes pushing the probe head towards the underground area.

In some embodiments, the method further includes rotating the probe head as the probe head is pushed towards the underground area.

In some embodiments, said inserting the probe head in the underground area to contact the soil includes inserting the probe head in a pre-made or pre-drilled hole.

In some embodiments, said inserting the probe head in the underground area to contact the soil includes inserting the probe head at a depth ranging from about <NUM> to about <NUM> under the soil surface.

In some embodiments, the method further includes obtaining one or more subsequent output signals representative of at least one characteristic of the soil, each subsequent output signal being measured at a different location of a field or at a different depth of the field.

In some embodiments, said projecting an illuminating beam towards the soil and through the transparent wall to irradiate the soil includes irradiating the soil through <NUM> degrees around the probe head.

In accordance with one implementation, there is provided an optical probe for analysing a soil located in an underground area using an illuminating beam. The optical probe includes a light source for generating the illuminating beam, a probe head insertable into the underground area to contact the soil, the probe head comprising a light collector for collecting and trapping a resulting light emanating from the soil after irradiation of the soil by the illuminating beam, and a detector for receiving the resulting light collected and trapped by the light collector and producing an output signal representative of at least one characteristic of the soil.

In accordance with another implementation, there is provided a method for analysing a soil located in an underground area using an illuminating beam. The method includes steps of inserting an optical probe including a light collector in the underground area to contact the soil; projecting the illuminating beam towards the soil through the light collector; collecting a resulting light emanating from the soil with the light collector; detecting the resulting light reflected by the soil; and outputting a signal representative of the soil condition.

In some embodiments, the light source includes at least one light-emitting diode.

In some embodiments, the spectral profile comprises a waveband ranging from about <NUM> to about <NUM>.

In some embodiments, the spectral profile comprises a visible waveband ranging from about <NUM> to about <NUM>.

In some embodiments, the light collector is optically transparent to the spectral profile of the illuminating beam.

In some embodiments, the light collector guides the resulting light scattered by the soil with total internal reflection.

In some embodiments, the light collector guides the resulting light reflected by the soil with total internal reflection.

In some embodiments, the light collector is a tubular-shaped light collector having an inner surface and an outer surface.

In some embodiments, the optical probe further includes a first radial lens optically coupled to the light source for generating a collimated illuminating beam towards the outer cylindrical periphery.

In some embodiments, the first radial lens is concentrically mounted within the light collector
In some embodiments, the collimated illuminating beam is generated in a radial direction of the tubular-shaped light collector.

In some embodiments, the light collector is made of clear fused quartz.

In some embodiments, the light collector is made of sapphire.

In some embodiments, the probe head has an inner portion defined by an inner periphery, and the optical probe further includes an optical diffuser optically coupled with the light collector for scattering the resulting light reflected by the light collector towards the inner portion of the probe head and a second radial lens for focusing the scattered light towards the detector.

In some embodiments, the second radial lens is concentrically mounted within the light collector
In some embodiments, the optical diffuser conforms with the inner periphery of the inner portion of the probe head.

In some embodiments, the optical probe further includes an optical fiber for guiding the light reflected from the light collector towards the detector.

In some embodiments, the light collector comprises a hole for receiving the optical fiber therein.

In some embodiments, the detector is a spectrometer
In some embodiments, the light collector encloses at least one of the light source and the detector.

In some embodiments, the optical probe further includes a processor for processing the signal representative of said at least one characteristic of the soil
In some embodiment, the optical probe further includes a control unit for operating and controlling at least one of the light source and the detector, the control unit being operatively connectable to the processor.

In some embodiments, the at least one battery has a cycle life of about <NUM> measurements.

In some embodiments, the body has a height ranging from about <NUM> to about <NUM>.

In some embodiments, the probe head has a height of about <NUM>.

In some embodiments, the probe head has an outer surface ranging from about <NUM><NUM> to about <NUM><NUM>.

In some embodiments, the characteristics of the soils are selected from the group consisting of: level of nutrients, level of available nutrients (or ionic concentration of the soil solution), temperature, moisture, pH, level of organic matter, and texture.

Other features and advantages of the present description will become more apparent upon reading of the following non-restrictive description of specific embodiments thereof, given by way of example only with reference to the accompanying drawings.

In the following description, similar features in the drawings have been given similar reference numerals, and, to not unduly encumber the figures, some elements may not be indicated on some figures if they were already identified in one or more preceding figures. It should also be understood herein that the elements of the drawings are not necessarily depicted to scale, since emphasis is placed upon clearly illustrating the elements and structures of the present embodiments.

The terms "a", "an" and "one" are defined herein to mean "at least one", that is, these terms do not exclude a plural number of elements, unless stated otherwise. It should also be noted that terms such as "substantially", "generally" and "about", that modify a value, condition or characteristic of a feature of an exemplary embodiment, should be understood to mean that the value, condition or characteristic is defined within tolerances that are acceptable for the proper operation of this exemplary embodiment for its intended application.

In the present description, the terms "connected", "coupled", and variants and derivatives thereof, refer to any connection or coupling, either direct or indirect, between two or more elements. The connection or coupling between the elements may be mechanical, physical, optical, operational, electrical, wireless, or a combination thereof.

In the present description, the terms "light" and "optical", and any variants and derivatives thereof, are intended to refer to electromagnetic radiation in any appropriate region of the electromagnetic spectrum and are not limited to visible light. For example, in one embodiment, the terms "light" and "optical" may encompass electromagnetic radiation with a wavelength ranging from about <NUM> to <NUM>. More particularly, although some embodiments of the present techniques can be useful in visible range applications, other embodiments could additionally or alternatively operate in other regions of the electromagnetic spectrum, for example in the millimeter, terahertz, infrared and ultraviolet regions.

It will be appreciated that positional descriptors indicating the position or orientation of one element with respect to another element are used herein for ease and clarity of description and should, unless otherwise indicated, be taken in the context of the figures and should not be considered limiting. It will be understood that spatially relative terms (e.g., "outer" and "inner", and "top" and "bottom") are intended to encompass different positions and orientations in use or operation of the present embodiments, in addition to the positions and orientations exemplified in the figures.

The expressions "illuminating beam" and "resulting light" are used throughout the description. The expression "illuminating beam" refers to light which is sent towards the soil under investigation. The expression "resulting light" refers to light emanating from the soil after its irradiation by the illuminating beam. The resulting light can include light that has not been absorbed by the sample or light scattered and/or reflected by the sample. The resulting light could be, in some context, the result of various physical processes (e.g., luminescence, photoluminescence, fluorescence, phosphorescence, and the like). Hence, the resulting light is the light emanating from the soil after the interaction between the illuminating beam and the soil.

The term "field" is herein used to refer to a region of land where trees, plants, crops and the like usually grow. The term "soil" is herein used for qualifying the underground area beneath the surface of the field, which may include the surface or a portion thereof.

Generally described, there is provided an optical probe for analysing a soil located in an underground area of a field using spectroscopy. The optical probe allows to assess in real time, or near real time, different characteristics of the soil, which are globally referred to as "the soil condition". These characteristics include but are not limited to level of nutrients present in the soil, temperature, moisture, pH, level of organic matter and ionic concentration of the soil solution.

The optical probe can be inserted in the underground area of the field to measure and monitor the soil condition in situ, i.e., without the need to extract a soil sample from the field prior to its characterization, thereby allowing to obtain a dynamic characterization of the soil, instead of a single static measurement of the soil condition, which is typically obtained in a laboratory. In some embodiments, this dynamic characterization can be, in turn, used to plan the maintenance of the field, plan the fertilization of the filed, evaluate and potentially prevent the risk of diseases for the tree(s), plant(s) and/or crop(s) growing in the field. Furthermore, by its size and configuration, the optical probe can also be moved from one location to another to take measurements at different locations of the field being characterized, thereby allowing to obtain a global representation (i.e., a "cartography") of the field. The optical probe also outputs measurements having a relatively high spatial precision.

The optical probe could be used to characterize different substrates such as, and without being limitative compost, manure, food, and/or plants. Of course, these examples are nonlimitative and serve an illustrative purpose only.

As it has been previously mentioned, the optical probe relies on spectroscopy, i.e., the production and investigation of spectra for determining the soil condition. The spectra are collected after the irradiation of the soil (or a portion thereof) with light.

Now turning to the Figures, different embodiments of the optical probe, as well as methods of using the same will be described.

Referring to <FIG>, embodiments of an optical probe <NUM> for analysing a soil located in an underground is illustrated. The optical probe <NUM> includes a light source <NUM>, a probe head <NUM> and a detector <NUM>, which will now be respectively described in greater detail.

Different configurations of the light source <NUM> can be used in the optical probe <NUM>. <FIG> illustrate a first embodiment of the light source <NUM> and <FIG> illustrate a second embodiment of the light source <NUM>. In nearly all implementations, the light source <NUM> is operable to generate an illuminating beam towards the soil.

In the first embodiment, illustrated in <FIG>, the light source <NUM> is embodied by one light-emitting diode (LED) <NUM>. It has to be noted that the light-emitting diode <NUM> could be, for example and without being limitative, replaced by a solid-state lighting source, including lasers, organic LEDs (OLEDs), incandescent lighting, halogen lighting, fluorescent light, infrared heat emitters, discharge lighting, combinations thereof or the like.

It has to be noted that the illuminating beam has a spectral profile which can be obtained with one or more light emitters. The spectral profile can either be relatively broad, i.e., the spectral profile covers a relatively large portion of the electromagnetic spectrum, or relatively narrow, i.e., covers only one or more portions of the electromagnetic spectrum. The combination of different light sources or emitters may be useful to extend the overall bandwidth of the emission spectrum and/or to maximize the relative power of some portions of the emission spectrum. In the context of soil analysis application, different wavelengths or different wavebands can serve different purposes. For example, and without being limitative, visible, infrared and blue light can be useful for detecting level of nutrients, level of available nutrients, ionic concentration of the soil solution, temperature, moisture, pH, level of organic matter and soil texture. Ultra-violet light can be useful for fluorescent matter, mineral and/or organic.

In some embodiments, the spectral profile comprises a waveband ranging from about <NUM> to about <NUM>. In other embodiments, the spectral profile of the illuminating could comprise a visible waveband ranging from about <NUM> to about <NUM>. In the context of the first embodiment of <FIG>, the spectral profile of the light source <NUM> is obtained with a single light source.

In the second embodiment, illustrated in <FIG>, the light source <NUM> includes a plurality of LEDs (labelled 28a, 28b, 28c and 28d in <FIG>). The illumination beam is thus obtained using a plurality of sub-sources, each emitting a respective illumination sub-beam. The sub-sources forming the light source <NUM> can be a stack of light-emitting diodes. The stack of light-emitting diodes includes at least one of a white broad band light-emitting diode, an infrared broad band light-emitting diode, a blue-light emitting diode and/or an ultra-violet light-emitting diode. In one implementation, the stack can include, for example and without being limitative, an ultra-violet light-emitting diode 28a, a blue light-emitting diode 28b mounted on the ultra-violet light-emitting diode 28a, an infrared light-emitting diode 28c mounted on the blue light-emitting diode 28b and a white broad band light-emitting diode 28d mounted on the infrared light emitting diode 28c. In this example, the ultra-violet light-emitting diode 28a can have a spectral profile comprising a waveband centered around <NUM> the blue light-emitting diode 28b can have a spectral profile comprising a waveband centered around <NUM>, the infrared light-emitting diode 28c can have a spectral profile comprising a waveband ranging from about <NUM> to <NUM> and the white broad band light-emitting diode 28d can have a spectral profile comprising a waveband ranging from about <NUM> to about <NUM>. Alternatively, the light source <NUM> or the sub-sources, e.g., the light-emitting diodes 28a-d could emit in the UV, the NIR region and/or the IR region of the light spectrum, depending on the soil or field under study. Each one of the light-emitting diodes 28a-d is optically coupled with a corresponding one of the radial lenses 36a-d, such that each sub-beam is collimated towards the soil and through the transparent wall <NUM>.

The light source <NUM>, including the single LED <NUM> and the stack of LEDs 28a-d, are typically configured for emitting light in a continuous regime. It will however be readily understood that the light source <NUM> could be operated either in a continuous regime or an intermittent regime, according to one's needs and/or the targeted application(s). One skilled in the art will readily understand that the choice and the configuration of the light source <NUM> may be limited and/or influenced by the predetermined parameters dictated by a given application. The predetermined parameters include but are not limited to wavelength, power, spatial profile and spectral profile.

Still referring to <FIG>, but more particularly to <FIG> and <FIG>, the probe head <NUM> will be described in greater detail. Generally described, the probe head <NUM> is insertable into the underground area to contact the soil, and so, in use, the soil generally surrounds at least partially the probe head <NUM>, and in some instances, mechanically contacts the probe head <NUM>, or at least a portion thereof.

The probe head <NUM> includes a transparent wall <NUM> defining a hollow chamber <NUM> within the probe head <NUM>. The transparent wall <NUM> has a top extremity <NUM> and a bottom extremity <NUM> defining an optical path <NUM> therebetween. The light source <NUM>, which has been previously presented, is mounted in the hollow chamber <NUM>. In some embodiments, the light source <NUM> is mounted near the bottom extremity <NUM> of the transparent wall <NUM>. The light source <NUM> is configured to generate the illumination beam towards the soil. The illumination beam passes through the transparent wall <NUM> to irradiate the soil, thereby producing a resulting light emanating from the soil, as defined above. After the irradiation of the soil by the illumination beam, a portion of the resulting light returns towards the probe head <NUM> and is guided in the transparent wall <NUM> by total internal reflection along the optical path <NUM>. In some instances, the transparent wall <NUM> is said to be configured for collecting and trapping the resulting light reflected by the soil, after an interaction between the illuminating beam and the soil. In some embodiments, the portion of the resulting light guided by the transparent wall comprises light scattered by the soil and/or light reflected by the soil. The transparent wall <NUM>, which acts as a light collector, is optically transparent to the spectral profile of the illuminating beam, or at least a portion thereof (i.e., the transparent wall <NUM> may or may not absorb a portion of the illuminating beam). The transparent wall <NUM> generally includes an inner surface <NUM> and an outer surface <NUM> and extend from the top extremity <NUM> to the bottom extremity <NUM>. In operation, the transparent wall <NUM> collects and guides the resulting light with total internal reflection. Total internal reflection occurs when a propagating wave is incident onto the boundary between two media at an angle larger than a critical angle with respect to the normal to the surface. The two media could, for example, be the soil (or a solution contained therein) and the transparent wall <NUM>. The critical angle is the angle of incidence above which the total internal reflection occurs, i.e., the angle above which the resulting light will be guided in the transparent wall <NUM>. The critical angle θc is given by Snell's law and can be written as: <MAT> wherein n<NUM> is the refractive index of the soil (or the soil solution contained therein) that is contact with the transparent wall <NUM> and n<NUM> is the refractive index of the material forming the transparent wall <NUM>.

Now referring to <FIG>, onto which a portion of the probe head <NUM> is shown, the illuminating beam is first illustrated as passing through the transparent wall <NUM> to irradiate the soil. It is to be noted that a change to the angle at which the illuminating beam intersects with the surface of the transparent wall <NUM> would result in a change of the proportion of light that is transmitted through the transparent wall <NUM>, as one skilled in the art would readily understand. In one embodiment exemplified in <FIG>, the illuminating beam, (which is labelled "<NUM>)" in <FIG>), is collimated and perpendicularly incident to the inner surface <NUM> of the transparent wall <NUM>, such that the illuminating beam is mostly transmitted therethrough. After its passage through the transparent wall <NUM>, the illuminating beam then interacts with the soil at a point (labelled "<NUM>)" in <FIG>. The point is illustrated as being in contact with the outer surface <NUM> of the transparent wall <NUM>, but, in some instances, a relatively small distance can separate the outer surface <NUM> of the transparent wall <NUM> from the point. The interaction between the illumination beam and the soil results in the illuminating beam being scattered by the soil. It has to be noted that a portion of the illuminating beam that interacts with the soil particles can be scattered in the form of light (i.e., radiative energy) and that a portion of this light will subsequently be guided in the transparent wall <NUM>. One would note that the scattering can either be elastic or inelastic. Another portion of the illuminating beam that interacts with the soil particles will not be scattered in the form of light but will rather be converted in another form of energy (i.e., non-radiative forms of energy). An example of non-radiative forms of energy is thermal or chemical energy. The portion of the illuminating beam converted in non-radiative energy will not be guided in the transparent wall. In some implementations, the illuminating beam is scattered in all directions or nearly all directions. The scattered or reflected light can either be collected by the transparent wall <NUM> or be retransmitted through the transparent wall <NUM>. In the first scenario, the reflected light will be referred to as the "resulting light scattered or reflected by the soil". This light is collected by the transparent wall <NUM> and is guided therein along the optical path <NUM>. In the second scenario, the light is not collected, and so is not guided along the optical path <NUM>. An example of this scenario is illustrated in <FIG> (see for example label "<NUM>)" and in <FIG>. Indeed, the light is not guided by the transparent wall <NUM> and therefore will not be received by any detector. In the first scenario presented above, only the portion of the resulting light that satisfies the conditions for total internal reflection, i.e., having the appropriate angle, is guided and collected by the transparent wall <NUM>, see for example the label "<NUM>)" in <FIG>. It has to be noted that the expressions "guided", "collected" and "trapped" by transparent wall <NUM> could be used interchangeably, as long as it refers to the light that follows the optical path <NUM> between the inner surface <NUM> and the outer interface <NUM> of the transparent wall <NUM>. It has to be noted that it is generally the light that travels from the bottom extremity <NUM> towards the top extremity <NUM> that is received at the detector, and thus analyzed, as it will be explained in greater detail later. In some embodiments, the portion of the light which is guided by the transparent wall <NUM> has interacted with the soil solution that is sticking to the outer surface of the transparent wall <NUM> or present at a relatively small distance from the transparent wall <NUM>. As exemplified in <FIG>, light coming from other source(s) than the light source <NUM>, which is sometimes referred as "optical noise", is not collected or guided by the transparent wall <NUM>. Moreover, it is to be noted that the specular reflections of the illuminating beam on the inner surface <NUM> and the outer surface <NUM> of the transparent wall <NUM> are typically not collected or guided by the transparent wall <NUM>.

In the illustrated embodiment, the optical probe <NUM> also includes a body <NUM> made of, for example and without being limitative, a tube <NUM> (see for example <FIG>). The tube <NUM> typically has two end portions: a top end portion <NUM> and a bottom end portion <NUM>. The top end portion <NUM> could be provided with handles, or similar structure, near or at its extremity, to help the user inserting the optical probe <NUM> into the ground or removing the optical probe <NUM> from the ground. The top end portion <NUM> usually refers to the portion of the tube <NUM> (or the body <NUM>) being exposed to ambient air when the optical probe <NUM> is inserted in the ground for analysis, while the bottom end portion <NUM> usually refers to the portion of the tube <NUM> (or the body <NUM>) being exposed to the underground area. The probe head <NUM>, and more particularly the transparent wall <NUM>, is typically mounted and/or affixed to the bottom end portion of the tube <NUM>. Other details regarding the body <NUM> will be provided later.

As depicted in the illustrated embodiments, the transparent wall <NUM> forms a tubular hollow chamber, i.e., the transparent wall <NUM> substantially defines the shape of a cylinder. The hollow chamber <NUM> is generally filled with air or with pure nitrogen and is confined by the inner surface <NUM> of the transparent wall <NUM>. The pure nitrogen can be useful in order to reduce or eliminate condensation in the hollow chamber <NUM>. It is to be noted that the outer surface <NUM> of the transparent wall <NUM> could be referred to as "an outer cylindrical periphery".

The inner surface <NUM> and the outer surface <NUM> of the transparent wall <NUM> are relatively "smooth", i.e., their surface roughness is such that it does not have significant effects on the optical properties of the transparent wall <NUM>. In some embodiments, the inner surface <NUM> and/or the outer surface <NUM> could be coated with an additional layer or treated with an appropriate physical or chemical process, for example and without being limitative, for enhancing predetermined optical properties of the transparent wall <NUM>, such as the reflexivity or the transmissivity of light. The transparent wall <NUM> is made from a material impermeable to the soil solution present in the soil, i.e., the soil solution cannot diffuse within the hollow chamber <NUM> and so does not penetrate the probe head <NUM>. As such, the transparent wall <NUM> is generally made from a non-porous material, or the porosity of the material is such that the soil solution stays outside of the probe head <NUM>.

The thickness of the transparent wall <NUM> can be from about <NUM> to <NUM>, wherein the thickness is measured between the inner surface <NUM> and the outer surface <NUM>. The transparent wall <NUM> is typically made from a single material or alloy (i.e., forms a monolithic and continuous piece of material). Alternatively, the transparent wall <NUM> could be made of a plurality of interconnecting pieces.

While the transparent wall <NUM> can, in some embodiments, forms a tube, e.g., when the probe head <NUM> is tubular, it could also take the shape of any other variants of a cylindrical component, i.e., any shapes having a longitudinal dimension substantially greater than a transverse dimension or being substantially narrow.

In the illustrated embodiments, the cross-section of the probe head <NUM> is substantially circular, but one would readily understand that the shape of the cross-section may change, and may include other rounded shapes, such as and without being limitative, ellipse, bubble, globe, hemisphere or rounded polygons. The shape of the probe head <NUM> could vary to include non-rounded shapes, e.g., parallelepiped, polygon, combinations and/or variants thereof, or any other shapes
As for its positioning, the probe head <NUM>, and in some instances, the transparent wall <NUM>, are typically fixed near or at the extremity of the bottom end portion <NUM> of the tube <NUM> forming the body <NUM>. More particularly, if the extremity of the bottom end portion <NUM> of the tube <NUM> is open (i.e., provided with a hole) a portion of the transparent wall <NUM> can be slidably inserted and engaged therein (i.e., in the open extremity of the bottom end portion <NUM> of the tube <NUM>). It is to be noted that supplementary fixing components or devices could be used to maintain the transparent wall <NUM> secured to the extremity of the bottom end portion <NUM> of the tube <NUM>, such as buttons, snaps, screws, glue, tape, welding, slits, guiding rails, combinations thereof, or any other components and/or means which would allow the transparent wall <NUM> to be affixed to the tube <NUM>.

In other embodiments, the bottom end portion <NUM> of the tube <NUM> and/or a region near its extremity could be threaded in its inner portion, and, similarly, a portion of the transparent wall <NUM> or a piece mounted near the top extremity <NUM> of the transparent wall <NUM> could also be threaded on its outer portion, such that the transparent wall <NUM> or the piece mounted near the top extremity <NUM> of the transparent wall <NUM> could be screwed (i.e., secured after a rotation) to the extremity of the bottom end portion <NUM> of the tube <NUM>.

Now turning to the dimensions of the transparent wall <NUM>, the transparent wall <NUM> could form, for example and without being limitative, a tube having an outside diameter of about <NUM> and a height (i.e., a longitudinal dimension measured between the top extremity <NUM> and the bottom extremity <NUM>) of ranging between about <NUM> and about <NUM>. Of course, the dimensions of the nominal diameter, the outside diameter and length of the light collector, depending on the surface required for the analysis, as well as other parameters (e.g., the depth of the soil at which the analysis is conducted).

The probe head <NUM> can have an outer surface area ranging from about <NUM><NUM> to about <NUM><NUM>. In some embodiments, the outer surface area of the transparent wall <NUM> ranges from about <NUM><NUM> to about <NUM><NUM>.

In some embodiments, the optical probe <NUM> allows an isotropic measurement of the soil and provides a <NUM>°-characterization around the probe head <NUM> (i.e., the optical probe <NUM> provides a view of the soil or the soil solution surrounding the transparent wall <NUM>), which is enabled by the <NUM> rotational degrees of symmetry of the tube.

As it has been previously mentioned, the hollow chamber <NUM> is typically filled with air or nitrogen. As such, the refractive index of the hollow chamber <NUM> can correspond to the refractive index of air (i.e., about <NUM>). For the light to be trapped within the transparent wall <NUM>, the material forming the transparent wall <NUM> should have an index of refraction higher than the index of refraction of air (i.e., the refractive index of the hollow chamber <NUM> is different than the refractive index of the material forming the transparent wall <NUM>). For example, and without being limitative, the refractive index of the transparent wall <NUM> could range from about <NUM> to <NUM>. In some embodiments, the refractive index of the transparent wall <NUM> is about <NUM>. In other embodiments, the refractive index of the transparent wall <NUM> is about <NUM>.

In some embodiments, the optical probe <NUM> include a first radial lens <NUM> optically coupled to the light source <NUM> for generating a collimated illuminating beam. The first radial lens <NUM> has a substantially cylindrical body and is concentrically mounted within the transparent wall <NUM>, in the hollow chamber <NUM>. In one embodiment, an outer periphery of the first radial lens <NUM> is in contact with the inner surface <NUM> of the transparent wall <NUM>. Alternatively, the first radial lens <NUM> could be mounted in a concentric manner with respect with the transparent wall <NUM>, but a relatively small gap could be maintained between the first radial lens <NUM> and the transparent wall <NUM>, so that the outer periphery of the radial lens <NUM> is not in contact with the inner surface <NUM> of the transparent wall <NUM>. As it has already been mentioned, the first radial lens <NUM> is optically coupled to the light source <NUM> and is generally located at the output of the light source <NUM>. Such a positioning allows to generate the collimated illuminating beam through transparent wall <NUM> to irradiate the soil. In some embodiments, for example when the probe head <NUM> is tubular, the first radial lens <NUM> can generate light towards the outer cylindrical periphery of the probe head <NUM>. In some embodiments, the collimated illuminating beam is generated in a radial direction, i.e., from a central portion of the probe head <NUM> towards the outer surface <NUM> of the transparent wall <NUM>.

As it has been previously described, the transparent wall <NUM> is generally made of a material optically transparent to the spectral profile of the illuminating beam. The optically transparent material can also have other properties, such as being resistant to abrasion. A broad variety of materials could be used, for example and without being limitative: clear fused quartz, quartz, sapphire, other types of glass and acrylic. Broadly, any optical materials configured for guiding light can included in the transparent wall <NUM>.

As better illustrated in <FIG> and <FIG>, the optical probe <NUM> includes an optical element <NUM> mounted in the hollow chamber <NUM>, near or at the top extremity <NUM> of the transparent wall <NUM>. The optical element <NUM> is configured to guide the portion of the resulting light guided in the transparent wall <NUM> from the transparent wall <NUM> to the detector <NUM>. In some embodiments, the optical element <NUM> comprises an optical diffuser <NUM> positioned near or at the top extremity <NUM>, in the hollow chamber <NUM>. The optical diffuser <NUM> is optically coupled with the transparent wall <NUM> for scattering the portion of the resulting light guided in the transparent wall <NUM> inside the probe head <NUM>. In some embodiments, such as the one illustrated in <FIG>, the optical diffuser <NUM> has the shape of a cone and is made from silicone. Such an implementation of the optical diffuser <NUM> will be referred to as a cone-shaped optical diffuser. As illustrated, the bottom portion of the cone-shaped optical diffuser is in mechanically contact the top extremity <NUM> of the transparent wall <NUM>, which allows the optical coupling between the transparent wall <NUM> and the cone-shaped optical diffuser. In the illustrated embodiment, the cone-shaped optical diffuser is optically coupled with the detector <NUM> with an optical fiber <NUM>. In other embodiments, such as the one illustrated in <FIG>, the optical element <NUM> could be a transparent optical guide, extending from the top extremity <NUM> of the transparent wall <NUM> to the detector.

In some embodiments, such as the ones illustrated in <FIG> and <FIG>, the optical probe <NUM> can also include a second radial lens <NUM>, similar to the first radial lens <NUM> that has been previously described. The second radial lens <NUM> can also have a substantially cylindrical body and can be concentrically mounted within the transparent wall <NUM>, in the hollow chamber <NUM>, e.g., an outer periphery of the second radial lens <NUM> can be in contact with the inner surface <NUM> of the transparent wall <NUM>. Alternatively, the second radial lens <NUM> could be mounted in a concentric manner with respect with the transparent wall <NUM>, but a relatively small gap could be maintained between the second radial lens <NUM> and the transparent wall <NUM>. The second radial lens <NUM> is configured to receive the scattered light and focusing the scattered light towards the detector <NUM>, with or without the intermediate of an optical component (e.g., an optical fiber <NUM>, such as the one illustrated in <FIG> can be provided between the second radial lens <NUM> and the detector <NUM>), as it will be described with greater detail herein below. In some embodiments, the second radial lens <NUM> receives light at its radial outer periphery and focuses the same such that the incoming light is focused towards the detector <NUM>.

In some implementations, the optical diffuser <NUM> can be replaced by an optical material, such as, for example and without being limitative, optically clear epoxy or a resin matrix having air bubbles therein, as illustrated in <FIG>. Such an optical material could be in contact or even connect the inner surface <NUM> of the transparent wall <NUM> with the second radial lens <NUM>. In one exemplary embodiment, the resin matrix has an aperture in its center to allow the insertion second radial lens <NUM> in the aperture.

In some embodiments, one or more optical component(s) can be provided between the second radial lens <NUM> and the detector <NUM>. For example, and without being limitative, an optical fiber <NUM> can be provided between the second radial lens <NUM> and the detector <NUM>. This embodiment is illustrated in <FIG> and <FIG>. Other optical elements affecting the light being guided from the second radial lens <NUM> to the detector <NUM> can be provided. Such optical elements include, but are not limited to lenses, mirrors, filters, and other suitable reflective, refractive and/or diffractive optical components.

In some embodiments, such as the one illustrated in <FIG>, the optical diffuser <NUM> conforms with the inner surface <NUM> of the transparent wall <NUM>, which can be, for example and without being limitative, an inner portion of the probe head <NUM>, such as the inner surface <NUM> of the transparent wall <NUM>. Alternatively, the optical diffuser <NUM> could also be a diffusing surface, or a coating of paint (or any other diffusing material applicable to a glass material).

In other embodiments, the optical probe <NUM> further comprises at least one optical fiber <NUM> for guiding the portion of the resulting light guided by the transparent wall <NUM> form the transparent wall <NUM> towards the detector <NUM>, as depicted in the illustration of <FIG>. The optical fiber <NUM> can be in mechanical contact with the transparent wall <NUM> or a portion thereof. In such embodiments, the transparent wall <NUM> can be provided with at least one hole for receiving the optical fiber <NUM> therein. Such a hole can be provided near or at the top extremity <NUM> of the transparent wall <NUM>. More particularly, the hole could be provided in a solid portion of the transparent wall <NUM> and extends in a direction parallel to a longitudinal axis of the transparent wall <NUM>, i.e., such that the input of the optical fiber is aligned within the longitudinal axis of the transparent wall <NUM>. In that scenario, the optical fiber <NUM> is placed in the optical path <NUM>. The hole can be deep enough that the optical fiber could be inserted and maintained in place with or without affixing means. This configuration allows the optical fiber to collect the resulting light being guided in the transparent wall <NUM>. Typically, each hole is sized and configured to receive one optical fiber. It is to be noted that the optical fiber(s) <NUM> could also be attached to the transparent wall <NUM> using appropriate fixing and/or sticking means.

In some embodiments, an additional layer made of, for example and without being limitative, a silver-based material, aluminum, or any other reflective coating(s) may be provided on the inner surface <NUM> and/or the outer surface <NUM> of the transparent wall <NUM>. In some scenarios, the use of such a reflective coating could increase the signal produced by the detector <NUM>. Indeed, if the transfer of light is more efficient, as it could be the case when an additional layer made of a reflective coating is provided, the detector <NUM> can receive more light, and therefore produces a stronger signal.

In some embodiments, the probe head <NUM> encloses at least one of the light source <NUM> and the detector <NUM>, i.e., at least one of the light source <NUM> and the detector <NUM> is mounted in the hollow chamber <NUM>. In some embodiments, the light source <NUM> and the detector <NUM> are enclosed in hollow chamber <NUM>.

It is to be noted that the light source <NUM>, the probe head <NUM> and/or the detector <NUM> could be coupled to optical components (not shown) configured to alter at least some of the properties of the light prior or after its interaction with the soil under investigation. The expression "optical components" herein refers, but is not limited to lenses, mirrors, filters, and other suitable reflective, refractive and/or diffractive optical components. It is to be noted that the relative position of the light source <NUM>, the probe head <NUM> and/or the detector <NUM> may also be adjustable.

Now turning to <FIG>, different embodiments of the detector <NUM> and different configurations of the detector <NUM> will now be described.

Generally, the detector <NUM> is configured to receive the portion of the resulting light guided in the transparent wall <NUM>. Upon reception of the portion of the resulting light guided in the transparent wall <NUM>, the detector <NUM> then outputs or produces an output signal representative of at least one characteristics of the soil. As previously mentioned, the characteristics of the soil are globally referred as the soil condition, and could include many different properties, such as the ones which have been previously described.

In some embodiments, the detector <NUM> is a light detector. An example of a light detector is a spectrometer, i.e. a device to measure the spectral properties of the portion of the resulting light guided in the transparent wall <NUM>. The detector <NUM> is generally responsive in the region of operation of the light source <NUM>, i.e., the detector <NUM> is sensitive to at least a portion of the wavelengths included in the spectral profile of the light source <NUM>. However, it will be readily understood that the detector <NUM> is sensitive to at least a portion of the wavelength included in the spectral profile of the portion of the resulting light guided in the transparent wall <NUM>. In some embodiments, the portion of the resulting light guided in the transparent wall <NUM> could be the result of various physical processes, for example and without being limitative fluorescence, luminescence, phosphorescence, photoluminescence, and the like. In some instances, appropriate filter(s) could be provided along the optical path <NUM> or between the components of the optical probe <NUM> in order to exploit one or more of the aforementioned physical processes.

Once received by the detector <NUM>, the resulting light may be converted to an electrical signal, electrical data and/or any other type of data using techniques already known by one skilled in the art. In some embodiments, the optical probe <NUM> further includes a processor <NUM>. The processor <NUM> is configured to receive the output signal representative of said at least one characteristic of the soil and determine a spectral content of the portion of the resulting light guided by the transparent wall <NUM>. In one embodiment, the processor <NUM> is an external computer. The external computer can be operatively connected to the optical probe <NUM>, either wirelessly or through physical connection, and can be configured for performing at least one of the following operations: sending instructions to the optical probe <NUM> or one of its components (e.g., the light source <NUM> or the detector <NUM>), receiving data from the optical probe <NUM>, controlling different parameters of the optical probe <NUM>, treating the collected data and/or generating visual representations (e.g., graph) of the soil conditions. An example of visual representation of the soil condition is illustrated in <FIG>, which illustrates a wavelength-dependent measurement of the soil at different measurements points. The general principles underlying such operations are generally well known to one skilled in the art but could of course be adapted in view of a particular targeted application. <FIG> illustrates similar measurements, but obtained with a plurality of LEDs.

As it will be readily understood, the processor <NUM> can be implemented as a single unit or as a plurality of interconnected processing sub-units. Also, the processor can be embodied by a computer, a microprocessor, a microcontroller, a central processing unit, or by any other type of processing resource or any combination of such processing resources configured to operate collectively as a processor. The processor <NUM> can be implemented in hardware, software, firmware, or any combination thereof, and be connected to the various components of the spectral identification system via appropriate communication ports.

With reference to <FIG> and <FIG>, two embodiments of the optical probe <NUM> being assembled are illustrated. The first embodiment is illustrated in <FIG> and the second embodiment is illustrated in <FIG>.

In the two embodiments, the optical probe <NUM> is provided with an electrical circuit <NUM> for powering the light source <NUM> and the detector <NUM>. The design and configuration of the electrical circuit <NUM> may vary according to the targeted application, but could include appropriate electronics components, such as for example and without being limitative resistors, switches, amplifiers, filters, diodes, transistor, and/or any other components already known by one skilled in the art.

The optical probe <NUM> can also include a control unit for operating and controlling at least one of the light source <NUM> and the detector <NUM> through the electrical circuit <NUM>. The control unit can be connected or part of the processor <NUM>. Alternatively, the control unit of the optical probe <NUM> could also be operatively connectable to a computer, a smartphone, or any other type of portable devices.

In some embodiments, the optical probe <NUM> includes a power unit <NUM> for powering the electrical circuit <NUM>. For example, and without being limitative, the power unit could include at least one battery. In some embodiments, the battery has a cycle life of about <NUM> measurements.

Now turning to <FIG> and <FIG>, the body <NUM> will now be described in greater detail. The body <NUM> is sized and configured to receive the electrical circuit <NUM> therein. In some embodiments, the body <NUM> has a hollow portion or is at least partially hollow and houses the electrical circuit <NUM>. The probe head <NUM> can also be mounted to the bottom end portion <NUM> of the body <NUM>, i.e., the extremity that is the closest to the ground. As it has been previously described, at least a portion of the probe head <NUM> can be engaged with or mounted to the body <NUM>.

In some embodiments, the body <NUM> has a height of ranging from about <NUM> to about <NUM> and the probe head <NUM> has a height ranging from about <NUM> to about <NUM>. In such embodiments, the optical probe <NUM> has a total height of about <NUM>. In some embodiments, the height of the body <NUM> can be adjustable, e.g., the height of the body <NUM> can be retractable.

In some embodiments, the optical probe <NUM> includes a sensing tip <NUM> provided near or at an extremity of the probe head <NUM>. The sensing tip <NUM> can be configured to measure at least one of the properties of the soil, such as for example and without being limitative, the electroconductivity, the pH of the soil and/or any other properties which can be sensed with the sensing tip <NUM>.

In some embodiments, the bottom extremity of the optical probe <NUM> is tapered (i.e., the end of the probe head <NUM> may reduce in diameter or thickness towards an extremity of end of the probe head <NUM>) The bottom extremity of the optical probe <NUM> is typically configured, sized and positioned to allow the optical probe <NUM> to be inserted to the ground. In some implementations, the optical probe <NUM> could include a helicoidal end part configured to enter the ground when being pushed towards the ground and rotated about a rotation axis, so that the probe head <NUM> is exposed to the soil in the underground area. In such embodiments, the helicoidal end part has a dimension and mechanical properties which allow sufficient engagement of the optical probe <NUM> with the ground, thus providing stability to the optical probe <NUM>, when inserted into the soil. In some embodiments, the optical probe <NUM> can be inserted at two different depths, e.g., about <NUM> and about <NUM>. Of course, one would have readily understood that the optical probe <NUM> can be inserted at any depth in the field. For example, and without being limitative, the probe head <NUM> can be inserted at a depth ranging from about <NUM> to about <NUM> under the soil surface.

In some embodiments, the bottom extremity of the optical probe <NUM> may be made from different materials. By way of an example, the extremity of the optical probe could be made from epoxy resin, acrylonitrile butadiene styrene (ABS) plastic, polylactic acid (PLA) plastic, aluminum or any other suitable materials.

The body <NUM> can be made from a broad variety of material. For example, and without being limitative, the body <NUM> may be made from any solid material such as polymers, including but not limited to limitative vinyl, fiberglass and rigid polyvinyl chloride (PVC), metals and metal alloys, including but not limited to aluminum and aluminium alloys, stainless steel, brass, copper, combinations thereof, or any other material that can be used to house the circuits <NUM> and to which the probe head <NUM> can be mounted. Of course, the body <NUM> can have various geometrical configurations (i.e., size and dimensions). As depicted however, the body <NUM> has a cylindrical shape, i.e. the body <NUM> is tubular. It will be readily understood that the body <NUM> could alternatively have a completely different shape. It has to be noted that the various examples provided herein are not limitative and serve an illustrative purpose only.

In accordance with another aspect, there is provided a method for analysing a soil located in an underground area. The method includes a step of inserting a probe head <NUM> in the underground area to contact the soil. As explained above, the probe head <NUM> includes a transparent wall <NUM> defining a hollow chamber <NUM> within the probe head <NUM> and the transparent wall <NUM> has a top extremity <NUM> and a bottom extremity <NUM>. The top extremity <NUM> and the bottom extremity <NUM> define an optical path <NUM> therebetween.

After the step of inserting the probe head <NUM> in the underground area to contact the soil, the method includes a step of projecting an illuminating beam towards the soil and through the transparent wall <NUM> to irradiate the soil, thereby producing a resulting light emanating from the soil and returning towards the probe head <NUM>. In some embodiments, projecting the illuminating beam towards the soil and through the transparent wall <NUM> to irradiate the soil includes irradiating the soil through <NUM> degrees around the probe head <NUM>.

Once the resulting light has returned towards the probe head <NUM>, the method includes a step of guiding, in the transparent wall <NUM>, a portion of the resulting light by total internal reflection along the optical path <NUM>.

The method also includes guiding, with an optical element <NUM>, the portion of the resulting light guided in the transparent wall <NUM> from the transparent wall <NUM> to the detector <NUM>. It has to be noted that the optical element <NUM> is generally provided near or at the top extremity <NUM> of the transparent wall <NUM>, and as such, only the resulting light guided from the bottom extremity <NUM> (or elsewhere) and towards the top extremity <NUM> is affected by the optical element <NUM>, meaning that it is typically the portion of the light guided by the transparent wall <NUM> that reaches the top extremity <NUM> of the transparent wall <NUM> that is guided towards the detector <NUM>.

After the portion of the resulting light in the transparent wall <NUM> has been guided, a step of detecting the portion of the resulting light guided in the transparent wall <NUM> is carried out. After the portions of the portion of the resulting light guided in the transparent wall <NUM> is detected by the detector <NUM>, the detector <NUM> outputs an output signal representative of the at least one characteristic of the soil. As it has been previously mentioned, the characteristics of the soil include, but are not limited to level of nutrients, level of available nutrients, ionic concentration of the soil solution, temperature, moisture, pH, and level of organic matter.

In some embodiments, the method also includes a step of processing the output signal representative of said at least one characteristic of the soil. The step of processing the output signal representative of the characteristic(s) of the soil can include, for example and without being limitative, receiving the output signal representative of the characteristic(s) of the soil and determining a spectral content of the portion of the resulting light guided in the transparent wall <NUM>.

The method can be adapted to measure at least one of the electroconductivity and the pH of the soil with a sensing tip <NUM> mounted at an extremity of the probe head <NUM>.

The optical probe <NUM> can be wirelessly operated, such that at least one of the light source <NUM> and the detector <NUM> is controlled at distance with a control unit or similar devices.

It has to be noted that the optical probe <NUM> can be inserted in the underground area using different device, apparatus, techniques and method. In a nonlimitative example, the method includes drilling a hole in the underground area to receive the probe head <NUM> therein. In another nonlimitative example, the method is adapted such that inserting the probe head <NUM> in the underground area to contact the soil includes pushing the probe head <NUM> towards the underground area. In this example, the method is optionally provided with a step of rotating the probe head <NUM> as the probe head <NUM> is pushed towards the underground area. When combined together, the steps of pushing and rotating the probe head <NUM> are similar to screwing the probe head <NUM> into the ground. In some embodiments, inserting the probe head <NUM> in the underground area to contact the soil includes inserting the probe head in a pre-made hole. The hole could be pre-drilled. The insertion of the probe head <NUM> can be made, for example and without being limitative, at a depth ranging from about <NUM> to about <NUM>.

While the method has been insofar described as having a single measurement step, it will have been readily understood that several measurement points are typically characterized in a field. For example, the method provided herein allows mapping the field at different geographical locations in order to obtain the characteristics of the soil at these different geographical locations or different depths (e.g., <NUM> and <NUM>). In these instances, the method includes obtaining one or more subsequent output signals representative of at least one characteristic of the soil. Each subsequent output signal is generally measured at a different location of the field one from another. Performing this step allows mapping the variations in different characteristics that might be present in the field, as it is often the case.

As such, the methods provided herein not only allow measuring properties of the soil in situ, but it can also be adapted to provide a map of the properties of the soil at various geographical points and depths of the field, thereby providing a global portrait of the field under investigation. This can be useful to provide some insights and analytics on the variable properties of the field, and thus can be used, for example and without being limitative, to identify trends in the dynamic of the field.

In accordance with one implementation, there is also provided a method for analysing a soil located in an underground area using an illuminating beam. Broadly described, the method according to this implementation includes inserting an optical probe including a light collector in the underground area to contact the soil; projecting the illuminating beam towards the soil through the light collector; collecting a resulting light reflected by the soil with the light collector; detecting the resulting light reflected by the soil; and outputting a signal representative of the soil condition. In some embodiments, the hole into which is inserted the optical probe can be made with a drilling device, such as for example and without being limitative an auger. In some embodiments, the hole can be made by inserting and pushing the optical probe into the ground. In some embodiments, the optical probe can be moved from one location to another to take measurements at different location of a field.

Claim 1:
An optical probe (<NUM>) for analysing a soil located in an underground area, the optical probe (<NUM>) comprising:
a probe head (<NUM>) insertable into the underground area to contact the soil, the probe head (<NUM>) comprising a transparent wall (<NUM>) defining a hollow chamber (<NUM>) within the probe head (<NUM>), the transparent wall (<NUM>) having a top extremity (<NUM>) and a bottom extremity (<NUM>) defining an optical path (<NUM>) therebetween;
a light source (<NUM>) mounted in the hollow chamber (<NUM>), the light source (<NUM>) being configured to generate an illumination beam towards the soil, the illumination beam passing through the transparent wall (<NUM>) to irradiate the soil, thereby producing a resulting light emanating from the soil, a portion of the resulting light returning towards the probe head (<NUM>) and being guided in the transparent wall (<NUM>) by total internal reflection along the optical path (<NUM>);
a detector (<NUM>) configured to receive the portion of the resulting light guided in the transparent wall (<NUM>) and outputting an output signal representative of at least one characteristic of the soil, the detector (<NUM>) preferably being a spectrometer; and
an optical element (<NUM>) mounted in the hollow chamber (<NUM>), near or at the top extremity (<NUM>) of the transparent wall (<NUM>), the optical element (<NUM>) guiding the portion of the resulting light guided in the transparent wall (<NUM>) from the transparent wall (<NUM>) to the detector (<NUM>).