Assembly for measuring one or more optical parameters of a medium and method for using the assembly - Patents.com

Abstract

The present disclosure provides an assembly for measuring one or more optical parameters of a medium, the assembly comprising: a light sheet generator (110) configured to provide a light sheet (192) extending in a first spatial dimension (101), the light sheet (192) having a propagation path in a second spatial dimension (102), the light sheet generator (110) comprising a polychromatic light source emitting polychromatic light and light sheet generating optics for reforming the light from the polychromatic light source into the light sheet (192); and an assembly for generating an intensity modulation having a periodic or substantially periodic pattern (11, 12, 13) in the first spatial dimension (101) in the light sheet (192). 2) to provide an intensity-modulated light sheet (193), a holder (145) for a sample (140) of medium configured to allow the intensity-modulated light sheet (193) to illuminate the sample, a dispersive element (3) arranged to receive the light transmitted through the sample and arranged to split the light sheet into its spectral components such that each spectral component forms its own separated light sheet, and an optical sensor configured to record the separated light sheet (195) in two dimensions. The present disclosure further relates to a method of using the assembly.

Description

[Technical Field]

[0001] The present disclosure relates to an assembly for measuring one or more optical parameters of a medium and a method of using the assembly, more particularly to an assembly for measuring one or more optical parameters of a medium and a method of using the assembly as defined in the introduction of the independent claims.

[0002] Background technology In some conventional techniques of spectrophotometry, monochromatic light (e.g., selected from a polychromatic light source) is used to illuminate the medium under test, and a photodetector is placed on the opposite side of the medium to the illuminated side to record the remaining light intensity after passing through the sample. By calculating the ratio of the light intensity before and after passing through the sample, the absorption or attenuation coefficient of the medium for the wavelength of the monochromatic light can be determined.

[0003] More complex methods of spectrophotometric measurement are also known. For example, a system for measuring the optical properties of a medium using monochromatic light is described in WO 2012 / 015344. A further example of an assembly for spectrophotometric measurement of turbid samples is disclosed in WO 2020 / 180233. There, spatially modulated illumination is used to mark the incident illumination, allowing for the suppression of undesired multiply scattered light.

[0004] A problem with prior art solutions to spectrophotometric measurements is the efficiency in making the measurements and the accuracy of the stored results.

[0005] Therefore, there is a need for alternative techniques to spectrophotometric measurements, which may be particularly pronounced for measurements in turbid media.

[0006] Summary of the Invention Structured Laser Illumination Planar Imaging (SLIPI) produces a much stronger signal than 2D imaging orthogonal SLIP, where side scattering is measured. To spectrally resolve SLIP measurements, the light sheet used is pre-spectralized in a planar direction perpendicular to the plane's propagation direction. This limits the measured signal and spectral resolution, especially when using a single-phase configuration without a phase shift of the structured illumination.

[0007] It is an object of the present disclosure to mitigate, alleviate or eliminate one or more of the drawbacks and disadvantages of the prior art identified above and to solve at least the problems mentioned above. According to a first aspect, there is provided an assembly for measuring one or more optical parameters of a medium, the assembly comprising: a light sheet generator configured to provide a light sheet extending in a first spatial dimension, the light sheet having a propagation path in a second spatial dimension, the light sheet generator comprising: a polychromatic light source emitting polychromatic light; and light sheet generating optics for reforming the light from the polychromatic light source into a light sheet; a light intensity modulator configured to provide an intensity-modulated light sheet by applying an intensity modulation having a periodic or substantially periodic pattern in the first spatial dimension to the light sheet; a holder for a sample of the medium configured to allow the intensity-modulated light sheet to illuminate the sample; a dispersive element arranged to receive the light transmitted through the sample and arranged to split the light sheet into its spectral components such that each spectral component forms its own separated light sheet; and an optical sensor configured to record the separated light sheet in two dimensions. This assembly for measuring one or more optical parameters of a medium can spectrally resolve planar imaging measurements using transmitted structured laser illumination. Because the sheet is not spectrally diversified before entering the sample, but instead is spectrally resolved after the sample, more information is obtained and the signal intensity is significantly improved. Because the diffraction direction is perpendicular to the modulation direction, the modulation frequency no longer affects the spectral resolution, and therefore higher spectral resolution can be achieved. Additionally, the generation of modulated light sheets is simplified because the light beam does not need to be diffracted before being shaped into a sheet and its intensity modulated.

[0008] The light sheet generating optics is any combination of lenses to form a sheet, for example a cylindrical concave lens followed by a circular convex lens, or any other device used to form lenses, including optional slits to further shape the sheet.

[0009] According to some embodiments, the dispersive element is a diffraction grating, which is advantageous because diffraction gratings are lightweight dispersive components.

[0010] According to some embodiments, the dispersive element is a prism, which is advantageous as it disperses light with very high precision.

[0011] According to some embodiments, the light sheet generator is fastened to and placed in abutment with the light intensity modulator, an advantage of this embodiment being that the assembly can be made more compact.

[0012] According to some embodiments, the optical intensity modulator is fastened to the sample holder and placed in abutment, an advantage of this embodiment being that the assembly can be made more compact.

[0013] According to some embodiments, the light intensity modulator is an imprint on the sample holder or container. An advantage of this embodiment is that the assembly can be more compact.

[0014] According to some embodiments, the optical sensor is a 2D CCD camera, allowing accurate 2D recording.

[0015] According to some embodiments, the light intensity modulator comprises an optical holder for the grating, the optical holder being electronically controlled and movable in the third spatial dimension, and a grating comprising a plurality of periodic patterns. An advantage of this embodiment is that the phase of the intensity-modulated light sheet can be rapidly changed to obtain portions in the dark areas of the intensity-modulated light sheet that, in combination with a previous recording, obtain signal strength and resolution of the measurement.

[0016] According to some embodiments, the light intensity modulator comprises an optical holder for a grating, the optical holder being electronically controlled and movable in a first spatial dimension, and a grating with a periodic pattern. An advantage of this embodiment is that the phase of the intensity-modulated light sheet can be rapidly changed to obtain portions in the dark areas of the intensity-modulated light sheet that, in combination with a previous recording, obtain signal strength and resolution of the measurement.

[0017] According to a second aspect, there is provided a method of using an assembly according to the first aspect for measuring one or more optical parameters of a medium, the method comprising providing a sample of the medium in a holder, illuminating the sample with an intensity-modulated light sheet provided by a light sheet generator and a light intensity modulator of the assembly, recording a plurality of separated light sheets by an optical sensor of the assembly, and determining the one or more optical parameters based on the recorded plurality of separated light sheets.

[0018] According to some embodiments, the method further includes moving an optical holder of the optical intensity modulator in a third spatial dimension such that light propagating within the assembly strikes the next subsequent first periodic pattern of the grating or, if present, the second periodic pattern, and repeating the method from the illuminating step.

[0019] According to some embodiments, the method further includes moving an optical holder of the optical intensity modulator in a first spatial dimension by a predetermined portion of the phase of the periodic pattern such that light propagating within the assembly is phase shifted by the predetermined portion of the phase, and repeating the method from the illuminating step.

[0020] The advantages and features of the second aspect are largely similar to those described above in relation to the first aspect, and the embodiments described in relation to the first aspect are largely compatible with the second aspect.

[0021] The present disclosure will become apparent from the following detailed description. The detailed description and specific examples disclose preferred embodiments of the present disclosure by way of example only. Those skilled in the art will understand that, upon reading the guidance of the detailed description, changes and modifications may be made within the scope of the present disclosure.

[0022] Thus, it is to be understood that the disclosure set forth herein is not limited to the particular components of the described apparatus or steps of the described methods, and that such apparatus and methods may vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting. It should be noted that, as used in this specification and the appended claims, the articles "a," "an," "the," and "said" are intended to mean that there are one or more of an element, unless the context clearly indicates otherwise. Thus, for example, reference to "a unit" or "the unit" may include several apparatuses, etc. Furthermore, the use of "comprising," "including," "containing," and similar expressions does not exclude other elements or steps.

[0023] The above objects, as well as additional objects, features and advantages of the present disclosure, will be more fully understood by reference to the following illustrative and non-limiting detailed description of exemplary embodiments of the present disclosure in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0024] [Figure 1a] FIG. 10 is a schematic block diagram illustrating an exemplary assembly according to some embodiments viewed in a third spatial direction. [Figure 1b] FIG. 1b is a schematic block diagram illustrating the exemplary assembly shown in FIG. 1a, viewed in a first spatial direction. [Figure 2] FIG. 1B is a perspective view of the components of the assembly disclosed in FIGS. 1a and 1b. [Figure 3]FIG. 1 illustrates an example of a grating according to the present disclosure having a periodic pattern. [Figure 4] FIG. 1 illustrates an example of a grating according to the present disclosure having a phase shift between multiple periodic patterns. [Figure 5] 1 is a flowchart illustrating exemplary method steps according to some embodiments.

[0025] MODE FOR CARRYING OUT THE INVENTION The present disclosure will now be described with reference to the accompanying drawings, in which preferred exemplary embodiments of the present disclosure are shown. However, the present disclosure may be embodied in other forms and should not be construed as limited to the embodiments disclosed herein. The disclosed embodiments are provided so that the scope of the disclosure will be fully conveyed to those skilled in the art.

[0026] As mentioned above, many conventional techniques for spectrophotometric measurements use a continuously applied monochromatic beam to illuminate a sample of the medium under test. To obtain information about more than one wavelength, a scan must be performed through all wavelengths of interest. Such techniques can be inefficient for making measurements.

[0027] Another technique for spectrophotometry is described in "Quantitative measurements of turbid liquids via structured laser illumination planar imaging where absorption spectrophotometry fails," Regnima et al., Applied Optics, Vol. 56, No. 13, May 2017, pp. 3929-3938, which uses two lasers, one with a wavelength of 450 nm and the other with a wavelength of 638 nm, exciting one laser at a time for the measurement.

[0028] Further techniques for spectrophotometric measurements are described in WO 2012 / 015344 and WO 2020 / 180233.

[0029] The following describes embodiments that enable efficient and accurate measurements. Additionally, some embodiments provide increased flexibility in measuring the optical properties of the medium under test, allowing accurate measurements to be performed on media with a wide range of different optical properties using the same assembly.

[0030] In general, the term "measurement" may refer to, for example, spectrophotometric measurements.

[0031] Also, in general, the term "optical parameter" may refer to any suitable optical parameter that describes an optical property, such as the absorption coefficient, the extinction coefficient (also known as the extinction coefficient), the scattering coefficient, the fluorescence quantum yield (QY), the phosphorescence quantum yield (QY), etc. The extinction coefficient is equal to the sum of the absorption coefficient and the scattering coefficient. Other examples of optical properties include properties related to one or more of concentration, average cross-sectional area, and particle size (if particles are present in the medium). Thus, these parameters may also be derived. Thus, measuring an optical parameter may be defined as measuring the (corresponding) optical property.

[0032] Also, in general, the term "medium" may refer to, for example, a liquid, a gel, a solid medium, or a gas. Some common applications include liquid media. Some embodiments may be particularly suited to measurements involving turbid and / or luminescent media, where turbidity includes scattering and absorption, and luminescence includes photoluminescence (e.g., fluorescence and / or phosphorescence).

[0033] Also, in general, illustrations of scattering are meant to relate to the emission of the photoluminescent medium, and vice versa.

[0034] Also, the term "light" generally refers to electromagnetic radiation having wavelengths within a particular range. This range may include what is commonly referred to as visible light (i.e., that portion of the electromagnetic radiation spectrum that is visible to the human eye). Alternatively or additionally, this range may include what is commonly referred to as non-visible light (i.e., that portion of the electromagnetic radiation spectrum that is invisible to the human eye), such as infrared (IR) light and / or ultraviolet (UV) light. The term "illumination" refers to illumination by light as defined above.

[0035] Also, the term "polychromatic" generally refers to something that contains two or more wavelengths (visible or non-visible) of the electromagnetic radiation spectrum.

[0036] Also, in general, the term (single) optical sensor may refer to an array / matrix of constituent optical sensors (each pixel of which corresponds to a constituent optical sensor, such as a digital camera with a photodetector), or to a single optical sensor element (single optical detector) configured to sweep a recording area.

[0037] 1a and 1b schematically illustrate an exemplary assembly for measuring one or more optical parameters of a medium, according to some embodiments, where Fig. 1a illustrates a side view of one variation of the assembly, and Fig. 1b illustrates a top view of the assembly.

[0038] The assembly comprises a light sheet generator (LSG) 110, a light intensity modulator (LIM) 130, a holder (HOLD) 145 for a sample (SAMP) 140 of the medium, a diffraction grating 3, and an optical sensor (SENS) 150.

[0039] The light sheet generator 110 is configured to provide a polychromatic light sheet 192 having a propagation path in the second spatial dimension 102 .

[0040] The second spatial dimension is non-parallel (typically orthogonal) to the first spatial dimension (e.g., in Euclidean coordinates). The first and second spatial dimensions, together with the third spatial dimension 103 (non-parallel and typically orthogonal to the first and second spatial dimensions), span three-dimensional space. The terms "spatial dimension" and "dimension" are used interchangeably herein.

[0041] A light sheet may be defined, for example, as light propagating along two or more paths within a single plane (eg, in Euclidean coordinates).

[0042] An optical spectrum extending in a first spatial dimension may be understood as an optical wavelength variation having the property that each coordinate along a path in the first spatial dimension experiences at most one wavelength of light.

[0043] The light intensity modulator (LIM) 130 comprises an optical holder 180 that holds gratings 2, 4 for modulating a light sheet 192. The light intensity modulator 130 is configured to provide an intensity-modulated multicolor light sheet 193 by applying (to the multicolor light sheet) an intensity modulation having a periodic or substantially periodic pattern in a first spatial dimension.

[0044] Examples of periodic patterns include patterns defined by Ronchi rulings, i.e., regularly spaced bars and spatial square waves, such as those shown in Figure 2 (e.g.,

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[0045] The optical intensity modulator may be, for example, a Ronchi grating 1. An example of a Ronchi grating 1 is shown in Figures 3 and 4.

[0046] The Ronchi grating of Figure 3 comprises a periodic pattern 11. The grating is intended to be movable to phase shift the periodic pattern. In the examples of Figures 1b and 2, the grating is movable in a first dimension 101 for this purpose.

[0047] The Ronchi grating of Figure 4 comprises three periodic patterns 11, 12, and 13 arranged next to each other. The central periodic pattern 12 has a phase shift p1 of 120 degrees relative to the right periodic pattern 13 and the left periodic pattern 11. The grating is intended to be movable to select one of the phase-shifted periodic patterns for an application. In the example of Figures 1b and 2, the grating is movable in the third dimension 103 for this purpose.

[0048] The grating of Figure 4 comprises a base plate 4 extending in a plane in two spatial directions 101, 103, and a plurality of n periodic patterns 11, 12, 13, each having a surface 18 and space 19 periodic wave optical mask with the same spacing frequency as shown in Figure 4. The periodic patterns 11, 12, 13 are arranged adjacent to each other on the base plate 4, with a phase shift ps1 between the masks of adjacent first periodic patterns. As disclosed in Figure 4, the first phase shift ps1 is 360 / n degrees. When n is 3 as in Figure 4, the phase shift ps1 is 120 degrees.

[0049] 1a, 1b and 2, a first aspect of the present disclosure provides an assembly for measuring one or more optical parameters of a medium, the assembly comprising: a light sheet generator 110 configured to provide a light sheet 192 extending in a first spatial dimension 101, the light sheet 192 having a propagation path in a second spatial dimension 102, the light sheet generator 110 comprising a polychromatic light source emitting polychromatic light and light sheet generating optics for reforming the light from the polychromatic light source into the light sheet 192; and an optical fiber having a periodic or substantially periodic pattern 11, 12, 13 in the first spatial dimension 101. 1 shows an assembly comprising a light intensity modulator 130 configured to provide an intensity-modulated light sheet 193 by applying an intensity modulation to a light sheet 192, a holder 145 for a sample 140 of medium configured to allow the intensity-modulated light sheet 193 to illuminate the sample, a dispersive element 3 arranged to receive the light transmitted through the sample and to split the light sheet into its spectral components such that each spectral component forms its own separated light sheet, and an optical sensor configured to record the separated light sheet 195 in two dimensions. The spectrally separated light sheet is in fact a continuum with an infinite number of sheets in the case of a uniform polychromatic light source.

[0050] 1a, 1b and 2, the dispersive element 3 is a diffraction grating, but in other embodiments the dispersive element 3 may be a prism. The optical sensor 150 is a 2D CCD camera.

[0051] It may be preferable to place the light intensity modulator as close to the sample as possible to preserve the spatial modulation until the modulated light sheet enters the sample, which is essentially achieved by an approach where the light intensity modulator is an imprint on the container for the sample.

[0052] Thus, the light sheet generator 110 may be fastened to and positioned in abutment with the light intensity modulator 130, and the light intensity modulator 130 may be fastened to and positioned in abutment with the sample holder 145, and the light intensity modulator may be an imprint on the sample holder 145 or the container.

[0053] The holder 145 for the sample of medium 140 is configured to allow the intensity-modulated polychromatic light sheet to illuminate the sample. For example, the holder may be positioned relative to the light intensity modulator and the light sheet generator such that when the sample is provided to the holder, the intensity-modulated polychromatic light sheet illuminates the sample.

[0054] Typically, the entire intensity-modulated polychromatic light sheet illuminates the sample, but some embodiments may apply a solution in which only a portion of the intensity-modulated polychromatic light sheet illuminates the sample.

[0055] The holder may be, for example, a stand for receiving the sample. The sample may be provided without a container (e.g., if the medium is a solid or a gel). Alternatively, the sample may be provided in a container (e.g., if the medium is a liquid or a gas), in which case the holder may be suitable for receiving the container containing the sample. An exemplary container is a cuvette (e.g., a glass cuvette).

[0056] The optical sensor 150 is configured to record the intensity (across the optical spectrum) of the light after it leaves the sample and has been spectrally separated by the dispersive element 3. The recorded intensities can then be used to determine one or more optical parameters.

[0057] Typically, the optical sensor may be a camera (eg, a charge-coupled device (CCD) camera or a scientific complementary metal-oxide-semiconductor (sCMOS) camera).

[0058] The optical sensor 150 is configured to record the intensity of the light that has been spectrally separated by the dispersive element 3 after leaving the sample (the so-called transmitted light, shown as 195 in Figures 1a and 1b) in opposition to the illumination.

[0059] 1a and 1b, the optical intensity modulator 130 includes a grating optical holder 180, which is electronically controlled and movable in the third spatial dimension 103, and a grating 4, whose assembly includes a plurality of periodic patterns 11, 12, and 13. Moving the grating 4 laterally or in the third spatial direction 103 can rapidly and precisely shift the phase of the periodic pattern. However, in an alternative embodiment, the optical intensity modulator 130 may include a grating optical holder 180, which is electronically controlled and movable in the first spatial dimension 101, and a grating 2, whose assembly includes the periodic pattern 11. This can save space because a grating with only one periodic pattern can be smaller. The phase shift is achieved by precise movement in the first spatial direction.

[0060] A second aspect of the present disclosure illustrates a method of using an assembly according to the first aspect to measure one or more optical parameters of a medium, the method comprising: providing 410 a sample 140 of the medium in a holder 145; illuminating 420 the sample with an intensity-modulated light sheet 193 provided by a light sheet generator 110 and a light intensity modulator 130 of the assembly; recording 430 a plurality of separated light sheets 195 by an optical sensor 150 of the assembly; and determining 460 one or more optical parameters based on the recorded plurality of separated light sheets 195.

[0061] According to one embodiment, the method includes moving 415 the optical holder of the optical intensity modulator 130 in the third spatial dimension so that the light propagating within the assembly strikes the next subsequent first periodic pattern 11, 12, 13 of the grating or, if present, the second periodic pattern 14, 15, 16, and repeating the method from the illuminating S2 step.

[0062] According to one embodiment, the method includes moving 416 the optical holder of the optical intensity modulator 130 in the first spatial dimension by a predetermined portion of the phase of the periodic pattern 11 so that the light propagating within the assembly is phase shifted by the predetermined portion of the phase, and repeating the method from the illuminating S2 step.

[0063] When using an assembly with a grating to determine one or more optical parameters, an array of the n most recently recorded measurements with different periodic patterns is maintained. When a new recording is made using a periodic pattern, that recording replaces the last measurement at that location in the array for that unique periodic pattern. If a second periodic pattern is present on the grating, a corresponding array (or a portion of the same but expanded array) is maintained for the second periodic pattern. In this way, new, updated calculations for determining one or more optical parameters can be made with each new recording. The effect is real-time results based on the n most recent recordings made when using the grating of Figure 4, but updated with each new recording. This achieves live measurements.

[0064] FIG. 5 is a flowchart illustrating an exemplary method 400 of using an assembly (eg, any of the assembly variations described in connection with FIGS. 1a-4) to measure one or more optical parameters of a medium.

[0065] The method may begin at optional step 405, where a range of light spectra for the multicolor light sheet (eg, 192) to be produced in the assembly is selected.

[0066] In step 410, a sample of the medium is provided in a holder of the assembly such that (eg, by position and / or orientation) the intensity-modulated polychromatic light sheet to be provided in the assembly illuminates the sample.

[0067] In step 420, the sample is illuminated by an intensity-modulated multi-colored light sheet (e.g., by turning on the light source of a light sheet generator configured to provide a multi-colored light sheet that is intensity-modulated by a light intensity modulator such as those illustrated above).

[0068] Modulated illumination allows the determination of the intensity of single light scattering from measurements of the modulation amplitude of the recorded signal. Application of different phases (by shifting the modulation) allows the intensity of single light scattering to be determined over the entire wavelength range of interest.

[0069] For example, a reconstructed image may be created from images of measurements for different phases after post-processing of the images such that the reconstructed image is free from multiple light scattering intensities and unwanted reflections, and can thus be used to estimate the extinction coefficient of the sample medium more accurately than if the multiple light scattering intensities were not suppressed.

[0070] In step 430, at least one image of the intensity of light exiting the sample as opposed to the illumination is recorded by an optical sensor, as illustrated above in connection with Figures 1a and 1b.

[0071] If more phases are to be measured (the Y path from optional step 435), the method returns to 420 where a new phase is applied and step 430 is repeated for the new phase. If no more phases are to be measured (the N path from optional step 435), the method proceeds to optional step 440.

[0072] In optional step 440, modulation amplitude is extracted from the recorded image. For example, this may be achieved by post-processing the recorded image(s) and extracting the amplitude of the modulation recorded for both the intensity of the light exiting the sample as opposed to the illumination (detection of the transmitted signal). As mentioned above, modulation amplitude may be used, for example, to distinguish between first order scattering and higher order scattering.

[0073] In optional step 445, it is determined whether the light penetration into the sample is sufficient to extract information of interest from the recorded image(s). For example, optional step 445 may include determining whether the extracted modulation amplitude is higher than a threshold for determining whether the light penetration into the sample is sufficient.

[0074] If the light penetration into the sample is insufficient (path N from optional step 445), the method may include, in optional step 447, increasing the light intensity of the light source or increasing the integration time of the optical sensor, returning to step 420, applying the adjustment and repeating the measurement.

[0075] If the transmission of light into the sample is sufficient (Y path from optional step 445), the method may proceed to optional step 450, where the measurements may be calibrated. For example, the calibration may include the application of displaceable monochromatic filter(s) (or filters having relatively narrow bandwidths) to provide spatial calibration of the light spectrum.

[0076] According to some embodiments of the various approaches presented herein, intensity modulation may enable the removal (or at least suppression) of one or more of background noise, background reflections, and diffuse transmitted light.

[0077] In general, all terms used herein should be construed in accordance with the ordinary meaning of the term in the relevant technical field unless a different meaning is clearly given and / or is implied from the context in which the term is used.

[0078] Reference is made herein to various embodiments, however, those skilled in the art will recognize numerous variations to the described embodiments that would still fall within the scope of the claims.

[0079] For example, method embodiments described herein disclose exemplary methods with steps that occur in a particular order. However, it is recognized that these sequences of events may be performed in other orders without departing from the scope of the claims. Furthermore, some method steps may be performed in parallel, even though they are described as occurring sequentially. Thus, the steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless a step is expressly described as following or preceding another step and / or it is implied that a step must follow or precede another step.

[0080] Similarly, it should be noted that in describing the embodiments, the division of functional blocks into specific units is in no way intended to be limiting. On the contrary, these divisions are merely examples. Functional blocks described herein as one unit may be divided into two or more units. Furthermore, functional blocks described herein as being implemented as two or more units may be combined into fewer (e.g., a single) units.

[0081] Any feature of any of the embodiments disclosed herein may be applied to any other embodiment where appropriate, and likewise, any advantage of any of the embodiments may be applied to any other embodiment, and vice versa.

[0082] It is therefore to be understood that the details of the described embodiments are merely examples presented for purposes of illustration and that all modifications that fall within the scope of the appended claims are intended to be covered.

Claims

1. 1. An assembly for measuring one or more optical parameters of a medium, comprising: a light sheet generator (110) configured to provide a light sheet (192) extending in a first spatial dimension (101), the light sheet (192) having a propagation path in a second spatial dimension (102), the light sheet generator (110) comprising a polychromatic light source emitting polychromatic light and light sheet generating optics for reforming the light from the polychromatic light source into the light sheet (192); a light intensity modulator (130) configured to provide an intensity-modulated light sheet (193) by applying an intensity modulation to the light sheet (192) having a periodic or substantially periodic pattern (11, 12, 13) in the first spatial dimension (101); a holder (145) for the sample of the medium, configured to allow the intensity-modulated light sheet (193) to illuminate the sample (140); a dispersive element (3) arranged to receive the light transmitted through the sample and arranged to split the light sheet into its spectral components so that each spectral component forms its own separate light sheet; an optical sensor configured to record said separated light sheet (195) in two dimensions; An assembly comprising:

2. Assembly according to claim 1, wherein the dispersive element (3) is a diffraction grating.

3. Assembly according to claim 1, wherein the dispersive element (3) is a prism.

4. 4. The assembly according to claim 1, wherein the light sheet generator (110) is fastened and arranged in abutment against the light intensity modulator (130).

5. 5. The assembly of claim 1, wherein the optical intensity modulator (130) is fastened to and arranged in abutment with the sample holder (145).

6. 6. The assembly of claim 1, wherein the light intensity modulator is an imprint on the sample holder (145) or a container.

7. 7. The assembly of claim 1, wherein the optical sensor (150) is a 2D CCD camera.

8. The optical intensity modulator (130) an optical holder (180) for the grating, the optical holder being electronically controlled and movable in a third spatial dimension (103); A grating (4) having a plurality of periodic patterns (11, 12, 13); 8. The assembly of claim 1, comprising:

9. The optical intensity modulator (130) an optical holder (180) for the grating, the optical holder being electronically controlled and movable in said first spatial dimension (101); A grating (2) with a periodic pattern (11); 8. The assembly of claim 1, comprising:

10. 10. A method of using an assembly according to any one of claims 1 to 9 for measuring one or more optical parameters of a medium, comprising the steps of: providing (410) a sample (140) of said medium in said holder (145); illuminating (420) the sample with the intensity-modulated light sheet (193) provided by the light sheet generator (110) and the light intensity modulator (130) of the assembly; recording (430) a plurality of separated light sheets (195) by the optical sensor (150) of the assembly; determining (460) the one or more optical parameters based on the recorded plurality of separated light sheets (195); A method comprising:

11. The method comprises: moving (415) the optical holder of the optical intensity modulator (130) in the third spatial dimension so that light propagating within the assembly strikes the next subsequent first periodic pattern (11, 12, 13) or, if present, second periodic pattern (14, 15, 16) of the grating; repeating the method from the illuminating step (420); 11. The method of claim 10, using the assembly of claim 8, further comprising:

12. The method comprises: moving (416) the optical holder of the optical intensity modulator (130) in the first spatial dimension by a predetermined portion of the phase of the periodic pattern (11) so that light propagating within the assembly is phase shifted by the predetermined portion of the phase; repeating the method from the illuminating step (420); 11. The method of claim 10, using the assembly of claim 8, further comprising:

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