Technical Field

The invention relates to a spectrometer device and to a spectrometer system for analyzing at least one sample, as well as to various uses of the spectrometer device. Such devices and systems can, in general, be used for investigation or monitoring purposes, in particular, in the infrared (IR) spectral region, especially in the near-infrared (NIR) and the mid infrared (MidlR) spectral regions, and for a detection of heat, flames, fire, or smoke. However, further kinds of applications are possible.

Background art

Various spectrometer devices and systems for investigations in the IR spectral region, in particular in the NIR and MidlR spectral regions, are known. Especially, spectrometer devices that comprise a combination of a parabolic mirrors and incandescent lamps have been proposed. Therein, the incandescent lamps are commonly used to cover the required wavelength range with their broad spectrum formed as a black-body radiator by Planck’s law. These setups however generally require precise component placement and narrow manufacturing tolerances, since even small deviations tend to trigger high spatial dependency of the illumination of the sample. The resulting high alignment efforts usually render large-scale production uneconomical.

One generally accepted approach for overcoming this issue is performing multiple measurements at different locations. Specifically, multiple measurements are typically performed, thereby converging in an averaging prediction about a material parameter to be measured. However, performing multiple measurements is cumbersome and costly.

Problem to be solved

It is therefore desirable to provide a spectrometer device and a spectrometer system that may, in particular, be suited for investigations in the IR spectral region, especially in the NIR and MidlR spectral regions, and which at least substantially avoid the disadvantages of known devices and systems of this type. In particular, it would be desirous to provide an improved, simple, cost-efficient and still reliable spectrometer device.

Summary

This problem is addressed by a spectrometer device, a spectrometer system and a use of a spectrometer device with the features of the independent claims. Advantageous embodiments, which might be realized in an isolated fashion or in any arbitrary combinations, are listed in the dependent claims as well as throughout the specification. As used herein, the terms “have”, “comprise” or “include” or any arbitrary grammatical variations thereof are used in a non-exclusive way. Thus, these terms may both refer to a situation in which, besides the feature introduced by these terms, no further features are present in the entity described in this context and to a situation in which one or more further features are present. As an example, the expressions “A has B”, “A comprises B” and “A includes B” may both refer to a situation in which, besides B, no other element is present in A (i.e. a situation in which A solely and exclusively consists of B) and to a situation in which, besides B, one or more further elements are present in entity A, such as element C, elements C and D or even further elements.

Further, it shall be noted that the terms “at least one”, “one or more” or similar expressions indicating that a feature or element may be present once or more than once typically are used only once when introducing the respective feature or element. In most cases, when referring to the respective feature or element, the expressions “at least one” or “one or more” are not repeated, nonwithstanding the fact that the respective feature or element may be present once or more than once.

Further, as used herein, the terms "preferably", "more preferably", "particularly", "more particularly", "specifically", "more specifically" or similar terms are used in conjunction with optional features, without restricting alternative possibilities. Thus, features introduced by these terms are optional features and are not intended to restrict the scope of the claims in any way. The invention may, as the skilled person will recognize, be performed by using alternative features. Similarly, features introduced by "in an embodiment of the invention" or similar expressions are intended to be optional features, without any restriction regarding alternative embodiments of the invention, without any restrictions regarding the scope of the invention and without any restriction regarding the possibility of combining the features introduced in such way with other optional or non-optional features of the invention.

In a first aspect, the present invention relates to a spectrometer device for analyzing at least one sample. The spectrometer device comprises: at least one light emitting element configured for emitting light for illuminating the sample; at least one optical detector configured for generating at least one detector signal according to an illumination of the optical detector by at least a portion of the light emitted by the light emitting element and reflected by the sample; and at least one waveguide comprising at least one reflective surface forming a pipe, the waveguide being configured for guiding the light emitted by the light emitting element in a direction towards the sample.

As used herein, the term “spectrometer device” is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to an apparatus that is capable of determining spectral information, such as information on at least one spectrum of at least one sample, by recording at least one measured value for at least one signal intensity, i.e. an intensity of electromagnetic radiation, such as a light intensity. The signal may specifically be generated, preferably as an electrical signal, by the detector of the spectrometer device with respect to a corresponding wavelength of light, or a partition thereof. The signal intensity may then be used for deriving an optical property of the sample. As an example, the spectrometer device may be configured for analyzing the sample by performing diffusive reflectance spectroscopy.

The term “sample”, as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to an arbitrary object or element, chosen from a living object or a non-living object, and having at least one optical property, the determination of the optical property, preferably, being of interest to a user when using the spectrometer device. The sample may specifically have any kind of characteristics, for example an inhomogeneous character, as will be outlined in further detail below.

As used herein, the term “light emitting element” is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special customized meaning. The term may specifically refer to an element configured for emitting light. In particular, the light emitting element may be or may comprise at least one light source which is known to provide sufficient emission, i.e. for the spectrometer device to detect, in a predefined optical spectral range, i.e. in infrared spectral range, such as in the near-infrared and/or in the mid infrared and/or in the far infrared spectral range. Specifically, the light emitting element may be selected from at least one of the following light sources: a thermal radiator, specifically an incandescent lamp, such as an incandescent lightbulb, or a thermal infrared emitter; a heat source; a laser, such as a laser diode; a light emitting diode (LED); a miniaturized thin-film emitter; a structured light source; a gas discharge lamp.

Herein, the term “light” may generally refer to a partition of electromagnetic radiation which is, usually, referred to as “optical spectral range” and which specifically comprises one or more of the visible spectral range, the ultraviolet spectral range and the infrared spectral range. The terms “ultraviolet spectral” or “UV”, generally, refer to electromagnetic radiation having a wavelength of 1 nm to 380 nm, preferably of 100 nm to 380 nm. The term “visible”, generally, refers to a wavelength of 380 nm to 760 nm. The terms “infrared” or “I R”, generally, refer to a wavelength of 760 nm to 1000 pm, wherein a wavelength of 760 nm to 3 pm is, usually, denominated as “near infrared” or “NIR” while the wavelength of 3 p to 15 pm is, usually, denoted as “mid infrared” or “Midi R” and the wavelength of 15 pm to 1000 pm as “far infrared” or “FIR”. Light used for the typical purposes of the present invention may specifically be light in the IR spectral range, preferably in the NIR spectral range, more preferred having a wavelength of 800 nm to 3000 nm, even more preferred having a wavelength of 1100 nm to 2500 nm.

In particular, the light emitted by the light emitting element may be within the near infrared spectral range, i.e. comprising electromagnetic radiation having wavelengths A of 760 nm < A < The term “optical detector” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to an optical sensor configured for detecting or measuring optical radiation, such as for detecting an illumination and/or a light spot generated by at least one light beam and/or ray of light. The detector may specifically comprise at least one photosensitive region. The photosensitive region may be configured for being illuminated, or in other words for receiving optical radiation, and for generating at least one signal, such as an electronic signal, in response to the illumination. The photosensitive region may be located on a surface of the photodetector. The photosensitive region may specifically be a single, closed, uniform photosensitive region. However, other options may also be feasible.

The term “waveguide” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a pipe-shaped reflector element configured for guiding and homogenizing the light emitted by the light emitting element by one or more internal reflections. In particular, the waveguide comprises at least one reflective surface forming a pipe. The waveguide may specifically have a least two openings and may be configured for guiding light from one end of the pipe to the at least one other end, i.e. by one or more internal reflections. In particular, the waveguide may not have a focal point. As an example, the waveguide may be one or more of a light pipe, a hollow light guide and a homogenizing rod.

The light emitting element may be arranged at least partially intruding into the waveguide. In particular, the light emitting element fully or partially may intrude into at least one end of the waveguide, i.e. into one end opening of the pipe. As an example, the light emitting element may be placed such as to extend into one of the at least two opening of the waveguide.

In particular, the waveguide may be or may comprise one or more of a hollow pipe and a pipe filled with at least one optically transparent material. Thus, the at least one reflective surface of the waveguide forming the pipe may be hollow and/or may be filled with at least one optically transparent material. As an example, the at least one reflective surface of the waveguide may form an enclosure within an optically transparent material, such that the material on the outside of the waveguide is the same as the material inside the waveguide, for example in case the waveguide is contained within ambient air or under water. Additionally or alternatively, the at least one reflective surface of the waveguide may at least partially enclose an optically transparent material being different from the ambient material, for example a glass material.

The waveguide may be a tapered pipe. For example, a cross-sectional area of one end of the waveguide may be smaller than the cross-sectional area of at least one second end of the waveguide, i.e. one end of the waveguide being a tapered pipe may be narrower than another end. In particular, the light emitting element may be arranged at a narrower end of the tapered pipe, specifically intruding into the narrower end of the tapered waveguide. Thus, in case the pipe is a tapered pipe, as an example, the light emitting element may be arranged at the narrower end, i.e. at an end of the pipe having a smaller cross-sectional area than another end. Specifically, the light emitting element may at least partially intrude into the narrower end of the tapered waveguide, i.e. of the tapered pipe. As an example, the waveguide may have the shape of a frustum having openings at both parallel planes.

In particular, an area ai of the opening of the waveguide where the light emitting element may be arranged may be smaller than an area a2 of the opening of the waveguide facing away from the light emitting element by at least a factor of 1.1. For example, the cross-sectional area of the narrower end may be smaller by at least a factor of 1.1. than the area of another end of the waveguide. In particular, a2 1.1 ai, specifically a ₂ 1.5 ai; more specifically a ₂ 1.7 ai.

A shape of the waveguide, i.e. the shape formed by the at least one reflective surface, may particularly be or may comprise one or more of a conical frustum or a polygon frustum. Thus, the waveguide may for example at least partially comprise the shape of a triangular frustum or a square frustum.

The waveguide may specifically comprise at least three flat reflective surfaces forming the pipe. In particular, the waveguide may comprise at least four reflective surfaces forming the pipe. As an example, the flat reflective surfaces may all have the same quadrilateral shape, such as a rectangular or trapezoidal shape. In particular, the waveguide may comprise a least three, preferably at least four, reflective surfaces of the same quadrilateral shape.

As an example, a length L of the waveguide, such as a distance between one end and another end of the waveguide, i.e. a shortest distance between the at least two openings, may exceed a maximum extension D of a smaller one of the openings of the waveguide, such as a maximum diameter or extension of the narrower end, or a maximum extension of the area ai, by at least a factor of 2. Specifically, the following may apply L > 2D, more specifically L > 3D.

The spectrometer device may specifically comprise a plurality of the light emitting elements and the plurality of light emitting elements may be arranged around a center point and/or a central light axis of the spectrometer device. As an example, the plurality of light emitting elements may be distributed equally around the center point and/or the central light axis, preferably in shape of a circle or an oval.

In particular, a number of waveguides of the spectrometer device may equal a number of light emitting elements of the spectrometer device. Thus, as an example, each waveguide may be appointed to one light emitting element and may be configured for guiding the light of that light emitting element towards the sample. For example, each waveguide may form a pair with exactly one light emitting element. The optical detector may be or may comprise a detector array comprising a plurality of detector elements, wherein the detector array is configured for generating the at least one detector signal according to an illumination of the plurality of detector elements.

The spectrometer device may comprise further elements or subsystems, such as at least one optical subsystem, i.e. a dispersive subsystem, configured for further guiding and/or filtering the light, for example the light reflected by the sample, within the spectrometer device.

In a further aspect, the present invention relates to a spectrometer system for analyzing at least one sample. The spectrometer system comprises the at least one sample and at least one spectrometer device according to any one of the embodiments disclosed above or below in further detail referring to a spectrometer device, wherein the sample and the spectrometer device are arranged and configured for essentially homogeneously illuminating at least one measurement area of the sample by the light emitted by the light emitting element and guided by the waveguide.

The term “essentially homogeneously illuminating” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a procedure of essentially homogeneous light reaching and/or impinging on an arbitrary object or element. The term “essentially homogeneous” as used herein, specifically may refer to a characteristic of optical radiation, i.e. of light, wherein the light has a constant intensity distribution I _const over a predefined area within a tolerance of ±20%, specifically within a tolerance of ±15%. In particular, essentially homogenous illumination of the sample may refer to a procedure of optical radiation having, within a tolerance of ±20%, specifically within a tolerance of ±15%, a constant light intensity, impinging within a predefined area, i.e. within the measurement area, on the sample.

The term “measurement area” as used herein, and also referred to as “sample spot area”, is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a spatially limited area of a sample surface on which the analyzation of the sample by the spectrometer device is based on. In particular, a size and/or extension as well as a shape of the measurement area may be dependent on at least one property of the spectrometer device or one or more of its components, i.e. on a size and/or power of the light emitting element.

As an example, the measurement area, i.e. the sample spot area, may be an area from which light may be collected by the spectrometer device and optionally transferred into the dispersive subsystem of the spectrometer, before illuminating the optical detector. In particular, a deviation from a preset nominal intensity in the illumination of the at least one measurement area may be less than or equal to 15 %, specifically less than or equal to 10 %, more specifically less than or equal to 5 %.

The sample may specifically, at least in the at least one measurement area, comprise at least one inhomogeneous characteristic. In particular, the sample may comprise a distinctly nonuniformity in at least one of its composition or character. As an example, the sample’s characteristic may be selected from the group consisting of the sample’s color, the sample’s shape, the sample’s particle size, the sample’s weight distribution, such as its mass distribution, the sample’s density, the sample’s material, the sample’s texture and the sample’s temperature. In particular, the characteristic of the sample may be selected from the group consisting of: a color, a shape, a particle size, such as a grain size or bean size, a mass distribution, a density, a material, a texture, a temperature.

In particular, the sample may have a degree of variance, such as a quantitatively or qualitatively measurable deviation from an average and/or nominal value of one or more of its characteristics, i.e. within the measurement area. In particular, the degree of variance of the at least one characteristic in the measurement area of the sample may be at least 10 %, specifically at least 20 %. For example, at least 10 %, specifically at least 20 %, of the sample shown in and/or corresponding to the measurement area may be different or may have a different characteristic than the rest of the sample within the measurement area.

As an example, the sample may be or may comprise a conglomerate of particles, such as a bulk material, for example grain kernels, coffee beans or the like. In this case specifically, the measurement area may be larger than at least one sample particle, i.e. by at least a factor of 2. Thus, as an example, at least one characteristic, such as a size and/or power, of the spectrometer device and/or of one or more of its components may be selected according to the sample to be analyzed.

In a further aspect, a use of a spectrometer device according to any one of the embodiments disclosed above or below in further detail referring to a spectrometer device is disclosed. Therein, the use of the spectrometer device for a purpose of analyzing the sample, for example of determining information related to a spectrum of the sample, is proposed. In particular, the spectrometer device may be used for a purpose of use selected from the group consisting of: an infrared detection application; a spectroscopy application; an exhaust gas monitoring application; a combustion process monitoring application; a pollution monitoring application; an industrial process monitoring application; a mixing or blending process monitoring; a chemical process monitoring application; a food processing process monitoring application; a food preparation process monitoring; a water quality monitoring application; an air quality monitoring application; a quality control application; a temperature control application; a motion control application; an exhaust control application; a gas sensing application; a gas analytics application; a motion sensing application; a chemical sensing application; a mobile application; a medical application; a mobile spectroscopy application; a food analysis application; an agricultural application, in particular characterization of soil, silage, feed, crop or produce, monitoring plant health; a plastics identification and/or recycling application.

The above-described spectrometer device, the spectrometer system and the proposed uses have considerable advantages over the prior art. Thus, generally, a simple, cost-efficient and still reliable spectrometer device for analyzing at least one sample is provided.

Specifically, the devices, systems and used as proposed herein may allow for a facilitated analyzing of samples, specifically of inhomogeneous samples. In particular, the waveguide, by internal reflection on its at least one reflective surface, preferably on its at least three reflective surfaces, more preferably on its at least four reflective surfaces, may increase randomization of an initial light distribution of the light emitted by the light emitting element. Thereby, for example, a homogeneity of the light may be increased. An increased homogeneity may specifically decrease dependency of the distribution of the light used for analyzing the sample from manufacturing tolerances, for example from precise positioning of a light emitting element. The present devices and systems may thus compared to know systems and devices decrease sensitivity to manufacturing tolerances and may increase measurement reliability and safety, e.g. even over typical quality fluctuations.

Compared to known devices and systems, the present devices and systems, specifically by being less sensible to fluctuations in manufacturing tolerances, i.e. manufacturing tolerances in the production of the light emitting elements, may allow for a higher reproducibility and better series manufacturability, thereby allowing for economical large-scale production.

In particular, when analyzing the sample with the spectrometer device, such as when performing diffusive reflectance spectroscopy by using the spectrometer device, on the sample, e.g. even on inhomogeneous samples, such as on grain kernels or coffee beans, the proposed spectrometer device may allow for a higher measurement reproducibility and thus may increase reliability of measurement results. This may specifically be the case if the measurement area, such as a measured sample spot area, exceeds, e.g. by a factor of at least 2, the typical grain size of the sample and/or if the illumination is homogeneous across the sample area.

The present devices and systems may further be scalable, allowing for a more precise adaption of the devices to the intended field of use and/or application. In particular, a size of the waveguide may be scalable and thus may be compatible with various light emitting elements of arbitrary size. Thereby, compared to known systems and devices, the present systems and devices, specifically the proposed spectrometer device, may allow for an adaption of its size to a wide variety of applications. In particular, the present devices may allow for being miniaturized, such as for being integrated into a wide variety of consumer electronics, e.g. into smartphones, wearables and/or tablets. Further, the present devices may allow for being maximized, such as for being integrated into large-scale monitoring and/or observation systems, for example in the field of recycling. Furthermore, the use of a waveguide may allow for multiple advantages of the proposed spectrometer device compared to known spectrometers, e.g. making use of parabolic reflectors. In particular, the waveguide, e.g. a rectangular light pipe, by being insensitive to variations of placement and shape of the light emitting element, i.e. of the light source, may allow for robustly illuminating the sample with homogeneous light. Thereby, homogeneous sample illumination may be secured and in turn a required measurement time may be reduced and user handling may be facilitated. Furthermore, the waveguide, e.g. a rectangular light pipe, by guiding the light via numerous reflections may homogenize the light in a position space, while not homogenizing the light in an angle space. This may particularly increase homogeneous sample illumination, specifically in case the sample is arranged close to a second opening of the waveguide, i.e. in a near field of the waveguide.

In addition, the waveguide of the spectrometer device may allow for a higher luminous efficacy, thereby lessening a required energy. Thus, the proposed spectrometer device may be more environmentally friendly than known devices and systems.

Summarizing and without excluding further possible embodiments, the following embodiments may be envisaged:

Embodiment 1 : A spectrometer device for analyzing at least one sample, comprising: at least one light emitting element configured for emitting light for illuminating the sample; at least one optical detector configured for generating at least one detector signal according to an illumination of the optical detector by at least a portion of the light emitted by the light emitting element and reflected by the sample; and at least one waveguide, e.g. configured for homogenizing the light emitted by the light emitting element, the waveguide comprising at least one reflective surface forming a pipe, the waveguide being configured for guiding the light emitted by the light emitting element in a direction towards the sample.

Embodiment 2: The spectrometer device according to the preceding embodiment, wherein the light emitting element is arranged at least partially intruding into the waveguide.

Embodiment 3: The spectrometer device according to any one of the preceding embodiments, wherein the waveguide is one or more of a hollow pipe and a pipe filled with at least one optically transparent material.

Embodiment 4: The spectrometer device according to any one of the preceding embodiments, wherein the waveguide is a tapered pipe, wherein the light emitting element is arranged at a narrower end of the tapered pipe, specifically intruding into the narrower end of the tapered waveguide.

Embodiment 5: The spectrometer device according to the preceding embodiment, wherein the waveguide has the shape of a frustum having openings at both parallel planes. Embodiment 6: The spectrometer device according to the preceding embodiment, wherein an area ai of the opening of the waveguide where the light emitting element is arranged is smaller than an area a2 of the opening of the waveguide facing away from the light emitting element by at least a factor of 1 .1 , such that a2 1.1 ai, specifically a ₂ 1 .5 ai; more specifically a2 1 .7 ai.

Embodiment 7: The spectrometer device according to any one of the two preceding embodiments, wherein a shape of the waveguide is one or more of a conical frustum or a polygon frustum, for example a triangular frustum or a square frustum.

Embodiment 8: The spectrometer device according to any one of the three preceding embodiments, wherein a length L of the waveguide exceeds a maximum extension D of a smaller one of the openings of the waveguide by at least a factor of 2, specifically L > 2D, more specifically L > 3D.

Embodiment 9: The spectrometer device according to any one of the preceding embodiments, wherein the waveguide comprises at least three, specifically at least four, flat reflective surfaces forming the pipe.

Embodiment 10: The spectrometer device according to the preceding embodiment, wherein the flat reflective surfaces all have the same quadrilateral shape, for example a rectangular or trapezoidal shape.

Embodiment 11 : The spectrometer device according to any one of the preceding embodiments, wherein the light emitted by the light emitting element is within the near infrared spectral range, i.e. comprising electromagnetic radiation having wavelengths A of 760 nm < A < 3 pm.

Embodiment 12: The spectrometer device according to any one of the preceding embodiments, wherein the light emitting element is selected from the group consisting of: a thermal radiator, specifically an incandescent lamp, such as an incandescent lightbulb, or a thermal infrared emitter; a heat source; a laser, such as a laser diode; a light emitting diode (LED); a miniaturized thin-film emitter; a structured light source; a gas discharge lamp.

Embodiment 13: The spectrometer device according to any one of the preceding embodiments, wherein the spectrometer device comprises a plurality of the light emitting elements and wherein the light emitting elements are arranged around a center point and/or a central light axis of the spectrometer device, preferably in shape of a circle or an oval.

Embodiment 14: The spectrometer device according to any one of the preceding embodiments, wherein a number of waveguides equals a number of light emitting elements.

Embodiment 15: The spectrometer device according to any one of the preceding embodiments, wherein the optical detector is a detector array comprising a plurality of detector elements, wherein the detector array is configured for generating the at least one detector signal according to an illumination of the plurality of detector elements.

Embodiment 16: A spectrometer system for analyzing at least one sample, the spectrometer system comprising the at least one sample and at least one spectrometer device according to any one of the preceding embodiments, wherein the sample and the spectrometer device are arranged and configured for essentially homogeneously illuminating at least one measurement area of the sample by the light emitted by the light emitting element and guided by the waveguide.

Embodiment 17: The spectrometer system according to the preceding embodiment, wherein a deviation from a preset nominal intensity in the illumination of the at least one measurement area is less than or equal to 15 %, specifically less than or equal to 10 %, more specifically less than or equal to 5 %.

Embodiment 18: The spectrometer system according to any one of the three preceding embodiments, wherein the sample, at least in the at least one measurement area, comprises at least one inhomogeneous characteristic, specifically a distinctly non-uniformity in at least one composition or character of the sample.

Embodiment 19: The spectrometer system according to the preceding embodiment, wherein a degree of variance of the at least one characteristic in the measurement area of the sample is at least 10 %, specifically at least 20 %.

Embodiment 20: The spectrometer system according to any one of the two preceding embodiments, wherein the characteristic of the sample is selected from the group consisting of: a color, a shape, a particle size, such as a grain size or bean size, a mass distribution, a density, a material, a texture, a temperature.

Embodiment 21 : A use of a spectrometer device according to any one of the preceding embodiments referring to a spectrometer device in one or more of: an infrared detection application; a spectroscopy application; an exhaust gas monitoring application; a combustion process monitoring application; a pollution monitoring application; an industrial process monitoring application; a mixing or blending process monitoring; a chemical process monitoring application; a food processing process monitoring application; a food preparation process monitoring; a water quality monitoring application; an air quality monitoring application; a quality control application; a temperature control application; a motion control application; an exhaust control application; a gas sensing application; a gas analytics application; a motion sensing application; a chemical sensing application; a mobile application; a medical application; a mobile spectroscopy application; a food analysis application; an agricultural application, in particular characterization of soil, silage, feed, crop or produce, monitoring plant health; a plastics identification and/or recycling application. Short description of the Figures

Further optional features and embodiments will be disclosed in more detail in the subsequent description of embodiments, preferably in conjunction with the dependent claims. Therein, the respective optional features may be realized in an isolated fashion as well as in any arbitrary feasible combination, as the skilled person will realize. The scope of the invention is not restricted by the preferred embodiments. The embodiments are schematically depicted in the Figures. Therein, identical reference numbers in these Figures refer to identical or functionally comparable elements.

In the Figures:

Figure 1 illustrates an embodiment of a spectrometer system with an embodiment of a spectrometer device in a schematic view; and

Figures 2 and 3 illustrate different examples of waveguide(s) and light emitting element(s) of an embodiment of a spectrometer device in a perspective view;

Figure 4 illustrates an exemplary embodiment of a measurement area of an inhomogeneous sample of a spectrometer system;

Figure 5 illustrates a graph showing differences between a nominal intensity distribution and intensity distributions obtained by displacing the at least one light emitting element from its nominal position for a waveguide compared to a parabolic mirror;

Figures 6a and 6b illustrate light intensity distribution in a measurement area of an embodiment of a spectrometer device where the filament position of an incandescent light bulb as light emitting element is in a nominal position (Figure 6a) and in a displaced position (Figure 6b);

Figures 7a and 7b illustrate light intensity distribution in a measurement area of a state of the art spectrometer where the filament position of incandescent light bulb is in a nominal position (Figure 7a) and in a displaced position (Figure 7b); and

Figures 8a to 8d illustrate measured light intensity distributions in a measurement area of four identically instructed embodiments of spectrometer devices.

Detailed description of the embodiments

Figure 1 shows, in a schematic view, an embodiment of a spectrometer system 110 with an embodiment of a spectrometer device 112 for analyzing at least one sample 114. The spectrometer system 110 comprises the sample 114 and the spectrometer device 112, wherein the sample 114 and the spectrometer device 112 are arranged and configured for essentially homogeneously illuminating, as indicated by the arrows in Figure 1, the at least one measurement area 116 of the sample 114 by light emitted by a light emitting element 118 and guided by a waveguide 120. The spectrometer device 112 comprises both the light emitting element 118 configured for emitting light got illuminating the sample 114 and the waveguide 120 comprising at least one reflective surface 122 forming a pipe and being configured for guiding the light emitted by the light emitting element 118 in a direction towards the sample 114. Further, the spectrometer device comprises at least one optical detector 124 configured for generating at least one detector signal according to an illumination of the optical detector 124 by at least a portion of the light emitted by the light emitting element 118 and reflected by the sample 114.

In Figures 2 and 3, different examples of waveguides 120 and light emitting elements 118 of an embodiment of a spectrometer device 112 are shown in a perspective view. In particular, the waveguide 120 may be or may comprise a reflector that does not have a focal point and may. As an example, the waveguide 120 may comprise four flat reflective surfaces 122 that form a rectangular tapered pipe, e.g. comprising at least two openings 126.

The light emitted by the light emitting element 118 may be homogenized by the waveguide 120 by one or more internal reflections, specifically at the reflective surfaces 122, as indicated by the reflection arrows in Figure 2. The light element 118 may be arranged at least partially intruding into the waveguide 120, specifically into a narrower end 128 of the waveguide 120, e.g. into a smaller one of the at least two openings 126, such as into the opening 126 having a smaller cross-sectional area.

Further, the waveguide 120 may have a length L, such as a shortest or minimum distance between the at least two openings 126. In particular, the length L may exceed a maximum extension D of a smaller one of the openings 126 of the waveguide 120, such as a maximum diameter or extension of the narrower end 128 by at least a factor of 2.

Furthermore, and as exemplarily illustrated in Figure 3, the spectrometer device 112 may comprise a plurality of the light emitting elements 118 and the plurality of light emitting elements 118 may be arranged around a central light axis 130 of the spectrometer device 112. In particular, the number of waveguides 120 of the spectrometer device 112 may equal a number of light emitting elements 118 of the spectrometer device 112. Thus, and as exemplarily illustrated in Figure 3, each waveguide 120 may be appointed to one light emitting element 118 and may be configured for guiding the light of that light emitting element 118 towards the sample 114. For example, each waveguide 120 may form a pair with exactly one light emitting element 118.

Figure 4 illustrates an exemplary embodiment of a measurement area 116 of an inhomogeneous sample 114 of a spectrometer system 110. In particular, the inhomogeneous sample 114, specifically in a section corresponding to the measurement area 116, may comprise a distinctly non-uniformity in at least one of its composition or character, e.g. in its particle size.

A graph showing differences between nominal intensity distribution and intensity distributions obtained by displacing the at least one light emitting element 118 from its nominal position for a waveguide 120 compared to a parabolic mirror is illustrated in Figure 5, wherein in the graph, the differences in the intensity distributions for the waveguide 120 are denoted with reference number 132 and the differences in the intensity distributions for the parabolic mirror are denoted with reference number 134. In particular, on the horizontal axis a position along a diameter of the measurement area 116 in millimeter [mm] is illustrated and on a vertical axis a deviation from the nominal intensity distribution is illustrated. Specifically, the illustrated graph may illustrate a difference between central cuts through the intensity distributions resulting from the use of a waveguide 120 and of a parabolic mirror. As may be seen in the graph, due to the homogenization of light by using the waveguide 120, the output light distribution may be independent of a precise positioning and shape of the light emitting element 118, i.e. of the light source. This may specifically show that the use of a waveguide 120 may render the spectrometer device 112 insensitive to manufacturing tolerances of light emitting elements 118, e.g. of incandescent lightbulbs, specifically when compared to the use of parabolic mirrors. Thus, this Figure may specifically demonstrate the stability of the spectrometer device 112 against displacements of its at least one light emitting element 118.

Figures 6a and 6b illustrate light intensity distribution in a measurement area 116 of an embodiment of a spectrometer device 112 comprising a plurality of waveguides 120 where the filament position of an incandescent light bulb as light emitting element 118 is in a nominal position (Figure 6a) and in a displaced position (Figure 6b). Specifically, in the displaced position the filament may be displaced from its nominal position along all three dimensions by a random distance within an interval from -200 pm to 200 pm. As may be seen when comparing Figures 6a and 6b, the light intensity distribution in the measurement area 116 for both, the nominal filament position and the displaced filament position do not differ from each other.

Figures 7a and 7b illustrate light intensity distribution in a measurement area 116 of a state of the art spectrometer comprising a plurality of parabolic mirrors where the filament position of an incandescent light bulb is in a nominal position (Figure 7a) and in a displaced position (Figure 7b). Specifically, in the displaced position the filament may be displaced from its nominal position along all three dimensions by a random distance within an interval from -200 pm to 200 pm. As may be seen when comparing Figures 7a and 7b, the light intensity distribution in the measurement area 116 for both, the nominal filament position and the displaced filament position significantly differs from each other.

In Figures 8a to 8d measured light intensity distributions in a measurement area 116 of four identically instructed embodiments of spectrometer devices 112 are illustrated. As may be seen when comparing Figures 8a to 8b with each other, the measured light intensity distribution in the measurement area 116 differ from each other only marginally. This may specifically show that the use of a waveguide 120 may render the spectrometer device 112 insensitive to manufacturing tolerances.

List of reference numbers spectrometer system spectrometer device sample measurement area light emitting element waveguide reflective surface optical detector opening narrower end central light axis intensity distribution differences for waveguide intensity distribution differences for parabolic mirror