Laser array excitation and multi-channel detection in spectrometers

Abstract

A spectrometer is provided that includes a plurality of excitation light sources (e.g., a plurality of laser light sources), a plurality of detector elements, and / or a plurality of excitation light sources and a plurality of detector elements. In one embodiment, for example, a spectrometer includes a light source adapted to provide an excitation incident beam, a detector adapted to detect a spectral signal; and an optical system adapted to direct the excitation incident beam toward the sample, receive a spectral signal from the sample, and provide the spectral signal to the detector. The light source comprises a plurality of laser sources adapted to provide a plurality of excitation incident beams through the optical system and / or the detector comprises a plurality of detector elements.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 401,709, filed on August 28, 2022, entitled “Laser Array Excitation and Multichannel Detection,” and U.S. Provisional Application No. 63 / 404,975, filed on September 9, 2022, entitled “Laser Array Excitation and Multichannel Detection,” each of which is hereby incorporated by reference as if fully set forth herein. Technical Field

[0003] The present disclosure relates to spectrometers using laser arrays for excitation and / or multi-channel detection. Background Art

[0004] A typical grating system of a spectrometer moves the excitation beam across the surface of the sample via moving parts. The grating system moves the excitation beam across the area of ​​the sample within a single acquisition and averages over the surface rather than producing discrete spectra. Summary of the Invention

[0005] A spectrometer is provided that includes a plurality of excitation light sources (e.g., a plurality of laser light sources), a plurality of detector elements, and / or a plurality of excitation light sources and a plurality of detector elements. In one embodiment, for example, the spectrometer includes a light source adapted to provide an excitation incident light beam, a detector adapted to detect a spectral signal, and an optical system adapted to direct the excitation incident light beam toward a sample, receive the spectral signal from the sample, and provide the spectral signal to the detector. The light source includes a plurality of laser sources adapted to provide the plurality of excitation incident light beams through the optical system, and / or the detector includes a plurality of detector elements.

[0006] In another embodiment, a spectrometer includes a light source adapted to provide an excitation incident beam and a detector adapted to detect a spectral signal. The optical system is adapted to direct the excitation incident beam toward a sample, receive the spectral signal from the sample, and provide the spectral signal to the detector. The optical system includes a beam expander adapted to expand the excitation incident beam.

[0007] The foregoing and other aspects, features, details, utilities, and advantages of the present invention will become apparent from reading the following description and claims, and from examining the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1An embodiment of an optical system for a spectrometer, such as but not limited to a Raman spectrometer, is shown.

[0009] Figure 2 An example laser array for providing multiple excitation beams is shown.

[0010] Figure 3 An example of laser excitation of a sample from an array excitation laser light source is shown.

[0011] Figure 4 An example of fitting a circle to a known straight line on a two-dimensional spectrometer detector is shown.

[0012] Figure 5A and Figure 5B An embodiment of a spectrometer comprising a two-dimensional detector is shown.

[0013] Figure 6 Examples of curvature (aberration) (top) and corrected linearized image (bottom) are shown.

[0014] Figure 7 An example of a detector consisting of pixels with a certain well depth and an example of digital readout are shown, where overflow includes values ​​larger than the pixel well depth that cause aberrations.

[0015] Figure 8 An example embodiment of a method for producing a flat optical image of a detector for producing a digital readout of the detector pixels without overflowing the pixel well depth is shown.

[0016] Figure 9 An embodiment of a spectrometer is shown in which a diode laser array is used to excite the sample and a two-dimensional (2-D) detector array is also used.

[0017] Figure 10 Shown are examples of difficult samples for imaging using Raman spectroscopy.

[0018] Figure 11 Examples of systems and methods suitable for detecting one or more targets within a complex sample are shown.

[0019] Figure 12 An embodiment of a spectrometer is shown where Raman collection is obtained using a 2-dimensional array.

[0020] Figure 13 Illustrate Raman collection that can be achieved using a laser array. Using this possibility, a sample can be illuminated in a relatively large area while being collected from a relatively small area that is a subset of the illuminated area.

[0021] Figure 14 Another embodiment is shown in which spacer excitation is provided.

[0022] Figure 15 A method for automatically triggering a sample in a fixed-focus spacer spectrometer (eg, a Raman spectrometer) is shown.

[0023] Figure 16 and Figure 17 Included are diagrams of example spectrometers and the spectrometer in use.

[0024] Figure 18 Schematic diagram of an embodiment of optics for imaging a laser array (eg, a VCSEL or diode laser array) onto a 2-D array detector.

[0025] Figure 19 An embodiment of a Raman spectrometer system including a combination of a laser array and a 2-D detector is described.

[0026] Figure 20 An example of spectrum collection using an addressable two-dimensional laser array and an addressable two-dimensional array detector is shown.

[0027] Figure 21 Another example of a spectrum collection method using an addressable 2-D laser array and an addressable 2-D array detector is shown.

[0028] Figure 22 Another example of a spectrum collection method using an addressable 2-D laser array and an addressable 2-D array detector is shown.

[0029] Figure 23 An example of fluorescence removal by BDM (background decomposition method) is shown.

[0030] Figures 24 to 27 An example spectral signal is shown.

[0031] Figure 28 Explain the origin of fluorescence in Raman spectroscopy applications.

[0032] Figure 29 An example spectral signal is shown.

[0033] FIG30 shows a diagram of the operation of the Hadamard transform. DETAILED DESCRIPTION

[0034] The following description is provided as an enabling teaching in the best, currently known embodiments of the present invention. For this reason, those skilled in the relevant art will recognize and understand that many changes can be made to the various aspects of the present invention described herein while still obtaining the beneficial results of the present invention. It will also be apparent that some of the desired benefits of the present invention can be obtained by selecting some of the features of the present invention without utilizing other features. Therefore, those skilled in the art will recognize that many modifications and adaptations of the present invention are possible, and even in some cases may be desirable, and are part of the present invention. Therefore, the following description is provided as an illustration of the principles of the present invention rather than a limitation thereof.

[0035] As used throughout, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a" component may include two or more such components unless the context clearly dictates otherwise. Additionally, the words "proximal" and "distal" are used to describe items or portions of items that are located closer to and farther from, respectively, a user or operator, such as a surgeon. Thus, for example, the tip or free end of a device may be referred to as the distal end, while the generally opposite end or handle may be referred to as the proximal end.

[0036] All directional references (e.g., upper, lower, upward, downward, left, right, leftward, rightward, top, bottom, above, below, vertical, horizontal, clockwise, and counterclockwise) are used for identification purposes only to aid the reader's understanding of the present invention and do not create any limitation on the position, orientation, or use of the present invention in particular. References to joining (e.g., attaching, coupling, connecting, etc.) are to be interpreted broadly and may include intermediate members between the connection of elements and relative movement between elements. Thus, references to joining do not necessarily infer that two elements are directly connected and in fixed relation to each other.

[0037] Ranges may be expressed herein as from "about" one particular value and / or to "about" another particular value. When such a range is expressed, another aspect includes from the one particular value and / or to the other particular value. Similarly, when a value is expressed as an approximation by using the antecedent "about," it will be understood that the particular value forms another aspect. It will also be understood that each endpoint of a range is significant both relative to the other endpoint and independently of the other endpoint.

[0038] As used herein, the terms "optional" or "optionally" mean that the subsequently described event or circumstance may or may not occur, and that the description includes instances where said event or circumstance occurs and instances where it does not.

[0039] As used herein, the term "substantially" may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related.

[0040] Figure 1 An embodiment of an optical system for a spectrometer, such as, but not limited to, a Raman spectrometer 10, is shown. In this embodiment, an excitation light source 12 (e.g., a laser) provides an excitation beam 14. The excitation beam is directed through a lens (lens 1) 16 and a beam expander 18 to a beam splitter 20 (e.g., a dichroic beam splitter). Beam splitter 20 directs the excitation beam 14 through a focusing lens (lens 2) 22 onto a sample 24. In this embodiment, the sample is disposed within a container 26 or behind a layer (such as a plastic bottle or layer).

[0041] The spectral signal 30 generated by the excitation light beam at the sample is at least partially directed back to the focusing lens (lens 2) 22 and is directed to another focusing lens (lens 3) 28 through the beam splitter 20. The focusing lens 28 focuses the spectral signal 30 on an aperture 32, through which the spectral signal passes and is received by a spectrometer 34 for analysis.

[0042] In one embodiment, the intensity of Raman scattering from materials behind a translucent barrier (such as a container) can be increased. One approach is to excite the sample over a larger area than the collection area. This can be achieved by a beam expander created by lens 116 and lens 222. This combination will create a large, extended laser illumination on the container. The lens 222 of the beam expander can also act as a collection lens for Raman scattering due to excitation of the sample 24. When focused to a distance from the sample equivalent to the focal length of lens 222, it will produce a collimated beam that passes through a dichroic beam splitter to lens 328, which focuses a small sampling area onto the aperture 32 of the spectrometer 34. The aperture 32 also acts as a spatial filter to eliminate off-axis radiation from the sample that enters the spectrometer 34.

[0043] Raman in this example is proportional to intensity (watts / area), and this approach reduces the intensity of the laser when it is expanded and produces a low Raman signal, or requires a relatively stronger laser than used in systems where the excitation signal is tightly focused on the sample. The expanded excitation laser signal also reduces laser hazards and can be used to provide eye-safe spacer lasers. Another approach is to use a laser array to generate an excitation area that is relatively large relative to the collection area.

[0044] Figure 2 An example laser array 35 is shown for providing multiple excitation beams 36. Each of the multiple excitation beams is directed through transfer optics and through the surface to a sample 38. Figure 2As shown, each of the multiple excitation beams 36 is directed toward the surface of the sample by a transfer optical device (optical system) so that the multiple excitation beams are dispersed across the surface of the sample. In the case where the target material is below the surface (e.g., a container such as a glass or plastic container), the multiple excitation beams can extend through the surface to the target material below (e.g., target particles) at multiple locations across the surface.

[0045] Figure 3 Examples of laser excitation of a sample from an array excitation laser light source are shown. In one example, shown in the top array configuration, only a single laser of the laser array is turned on. In another example, shown in the middle array configuration, each laser of the array is turned on, and the spectrometer detects both light from the surface (aligned with the aperture) and subsurface light scattered from lasers that are not aligned with the aperture. In yet another example, shown in the bottom array configuration, a combination of laser excitation and detection is shown. In the case of the bottom array configuration, the spectrometer can collect spectral signals where the laser light spatially coincides with the excitation region and the laser light also illuminates the sample spatially offset from the collection region.

[0046] In one embodiment, for example, a straight slit aperture can result in a cone of diffraction off the grating, due to the change in diffraction angle with the angle of incident light on the grating. Vertical off-axis light will diffract at a lower angle than on-axis light. This cone is projected onto the imager and produces a curved image. One way to correct for this curvature is to use a curved slit aperture.

[0047] With a 2D sensor, curvature can be corrected in software post-processing by fitting a circle to a known line and using the radius to adjust the alignment of each row of pixels relative to the other rows. Figure 4 Shows an example of fitting a circle to a known line.

[0048] Figure 5A and Figure 5B An embodiment of a spectrometer comprising a two-dimensional detector is shown. In this embodiment, the detector collects Raman in binnable columns. Figure 5A In , the spectrometer design creates curved Raman images that are not well averaged (binned) along the columns. Figure 5B In the example, the Raman signal has been digitally linearized and can be correctly averaged (binned) along the columns.

[0049] Figure 6 Examples of curvature (aberration) (top) and corrected linearized image (bottom) are shown.

[0050] Figure 7 An example of a detector consisting of pixels with a certain well depth and an example of digital readout are shown, where overflow includes values ​​larger than the pixel well depth that cause aberrations.

[0051] Figure 7 This results in an inaccurate distribution of digital intensities due to overflow. If the digital intensities are determined by binning (adding) the intensities, the resulting value will be independent of the input signal.

[0052] Figure 8 An example embodiment of a method for producing a flat optical image of a detector for producing a digital readout of the detector pixels without overflowing the pixel well depth is shown.

[0053] exist Figure 8 In

[15] , by optically flattening the input using a negative (concave) cylindrical lens, the intensity is distributed across the pixels and spillover is eliminated. Now, when the digital signal is binned, it is proportional to the input radiance signal.

[0054] Figure 9 An embodiment of a spectrometer is shown in which a diode laser array is used to excite the sample and a two-dimensional (2-D) detector array is also used. In this example, the sample is inhomogeneous, with only two particles of interest and a surface that also contributes to the signal. The signals from the pure substrate and the sample mixed with spectral features from the substrate can be mathematically separated into pure sample spectra.

[0055] Figure 9 A diagram of a spectrometer apparatus comprising a two-dimensional (2D) diode laser array and a two-dimensional (2D) array detector is shown. In this embodiment, the spectrometer is adapted to detect a target sample of a non-uniform sample. In this example, the non-uniform sample comprises a plurality of target materials disposed on a surface. Without a large sample area, the spectrometer can detect only the surface or a combination of the surface and the target. Even with large area illumination, the spectrum will be a convolution of the surface spectrum and the target spectrum. Using a diode laser array and a multi-channel detector, discrete spectra of the surface and the target can be observed. Algorithms can be used to separate the spectra to accurately identify the target material.

[0056] Figure 10 Examples of difficult samples for imaging using Raman spectroscopy are shown. In the first example, shown on the left, the field sample has a crack or fissure containing the sample target, but in the spectrum, the surface material interferes. In the second example, shown on the left, the sample includes multiple target sample particles that are arranged in a non-uniform manner along the surface material, as described above with reference to Figure 9 In various embodiments, the spectrometer is adapted to separate a signal from a surface from a target.

[0057] Figure 11 Examples of systems and methods suitable for detecting one or more targets within a complex sample are shown. Figure 11 The concept of a laser array coupled to a two-dimensional detector is illustrated. The spectra of the target and the surface are distinguishable and can be separated into discrete spectra on the 2-dimensional array.

[0058] exist Figure 11 In the embodiment shown, for example, a vertical cavity surface emitting laser (VCSEL) array provides multiple excitation light signals. Each of the excitation light signals passes through a beam splitter (e.g., a dichroic beam splitter) and is focused onto a portion of a complex sample via a collection lens as shown. Multiple spectral signals (e.g., Raman excitation signals) return to the collection lens and are collimated toward the beam splitter. The spectral signals are reflected by the beam splitter onto a two-dimensional (2D) detector (e.g., a multi-CMOS 2D detection array).

[0059] Figure 11 The ability of a laser array and a two-dimensional detector to generate a unique discrete spectrum for each laser position (spatially separated on the surface) is also demonstrated. This is advantageous over approaches that raster over an area and generate an average of the surface and target spectra.

[0060] The laser array also produces large array excitation and detection without moving parts. Current raster systems use moving parts to move the beam across a surface, rastering the entire area within a single acquisition, thus averaging over the surface rather than producing discrete spectra. While the current raster pattern is circular, the individually addressable laser array can produce any pattern shape.

[0061] Figure 11 Also shown is a CMOS detector array. In one embodiment, the CMOS detector array can be used with an FPGA to quickly collect and transfer the entire spectrum to memory. Mathematical operations are performed on the device using processing from the FPGA (field programmable gate array) rather than sending the raw data to a processor to perform the mathematical operations, thereby providing speed gains.

[0062] DSERS. Dynamic surface-enhanced Raman spectroscopy (DSERS) is described in BL Scott and KT Carron, "Dynamic Surface Enhanced Raman Spectroscopy (SERS): Extracting SERS from Normal Raman Scattering," Anal. Chem. 2012, 84, 8448-8451, which is incorporated herein by reference as if fully set forth herein. The DSERS concept has been hampered by the time required to acquire data from a CCD, read out the data, and store the data.

[0063] CMOS cameras are video devices with very high readout rates. Using a CMOS or similar detector provides the ability to view smaller particles in a flow (microfluidics) or static fluid (Brownian motion). Typically, the smaller the particle, the faster it moves, and this requires an instrument with a fast readout rate. CMOS detectors can improve this situation.

[0064] Figure 12 An embodiment of a spectrometer is shown in which Raman collection is obtained using a 2-dimensional array. In this example, eight lasers provide separate excitation beams, and each beam excites the sample, as Figure 2 In this embodiment, the Raman signal from each of the eight lasers is collected along 8 rows (regions of interest) of the 2-D detector and the Raman signal is observed along the rows.

[0065] Figure 13 Another embodiment of a Raman spectrometer is shown, in which a single diode laser excitation is used and detection of the Raman signal is performed via a linear one-dimensional (1-D) detector.

[0066] Figure 13 This illustrates the Raman collection that can be achieved using a laser array. Using this possibility, a sample can be illuminated over a relatively large area while being collected from a relatively small area that is a subset of the illuminated area. This also refers to Figure 3 and Figure 4 One advantage is that a semi-transparent container or barrier can transmit the illumination to a highly scattered power level and will generate Raman signals below the surface. This approach can enhance the subsurface signal compared to the container's signal.

[0067] Figure 14 Another embodiment is shown in which spacer excitation is provided. In this embodiment, the focus spacer includes a Raman excitation laser and at least one visible aiming laser (in this embodiment, a pair of visible aiming lasers). The user can identify the focus by aligning the visible aiming laser with the target.

[0068] Figure 14 Describes an operating mode that uses the intersection of two visible laser beams to define the focus of a fixed-focus spacer Raman system. In this mode, the operator can start the acquisition when the beams are aligned. This can be difficult as two hands may be required to hold the system and the acquisition button must be pressed precisely when the beams are aligned.

[0069] Figure 15A method for automatically triggering a sample in a fixed-focus spacer spectrometer (e.g., a Raman spectrometer) is shown. In this embodiment, a photodiode detector receives a reflected signal from a visible aiming laser, and when the spectrometer is focused, the photodiode (or other detector) detects the signal and illuminates the Raman excitation laser to generate a spectral signal for analysis. Figure 15 In the illustrated embodiment, for example, when the spectrometer is focused on the sample, a visible laser signal is reflected along the detection axis of the spectrometer. The visible laser signal is reflected by a dichroic beam splitter away from the optical detection portion of the spectrometer and directed to a detector, such as a photodiode as shown. In one embodiment, for example, the photodiode detects the signal and provides a leading edge or other signal indicating that the spectrometer is focused on the sample, and initiates spectroscopy of the sample by illuminating it with a Raman excitation laser.

[0070] Figure 15 The illustrated embodiment provides an improved solution to fixed-spacer systems. In this case, one beam intersects the laser excitation beam. A dichroic beam splitter is used to direct the visible laser beam to a photodiode, which generates a trigger to automatically start acquisition.

[0071] Figure 16 and Figure 17 Included are diagrams of example spectrometers and the spectrometer in use.

[0072] Figure 18 This figure illustrates an embodiment of optics for imaging a laser array (e.g., a VCSEL or diode laser array) onto a 2-D array detector. In this embodiment, for example, each laser results in a separate spatial position on the surface, which can be mapped back to the position of the detector. In this embodiment, the purity of the spatial pattern can be increased or decreased without becoming chaotic.

[0073] Figure 19 An embodiment of a Raman spectrometer system comprising a combination of a laser array and a 2-D detector is described. The laser array may be composed of VCSEL lasers that emit narrow frequency light, but depending on the manufacturing characteristics, they may emit at unique individual wavelengths. In other words, they may be a group of lasers that each operate at a narrow frequency, but within the group, their wavelengths may vary. This is in Figure 20 The left-hand side of the Figure 20 Examples are shown in which one or more subsets of a laser array are controllable. For example, individual lasers, rows of lasers, and / or columns of lasers may be individually controllable. Figure 20 In the example of FIG. 5 , for example, all lasers may be turned on or off except for a first addressable row of lasers which are controlled to be off or on, respectively.

[0074] Due to the spatial purity produced by optical devices, e.g. Figure 19 As shown, the Raman from these lasers will be produced on the array as individual spectra with shifted Raman signatures due to the change in wavelength. The result is a set of Raman spectra collected simultaneously (in parallel) with slightly shifted Raman signatures.

[0075] This data set is known for its ability to be decomposed into moving and non-moving data sets. For Raman spectroscopy applications, this means that the slowly or unchanging fluorescence background can be separated from the rapidly changing Raman peaks.

[0076] Figure 20 An example of spectral collection using an addressable two-dimensional laser array and an addressable two-dimensional array detector is shown. In one embodiment, for example, multiple lasers in a 2-D laser array are turned on, and the remaining lasers in the 2-D laser array are turned off. For example, a single addressable row of the laser array can be turned on or off, and the remaining lasers in the array can be turned off or on, respectively. Detector readout can be similarly performed along the first plurality of detectors of the 2-D array detector. For example, a single row aligned with the center laser of the laser array can be turned off.

[0077] Figure 21 Another example of a spectrum collection method using an addressable 2-D laser array and an addressable 2-D array detector is shown. In one embodiment, for example, all lasers except one can be turned off (or on), and a readout of rows of the detector array is performed along the rows aligned with the turned-off lasers to generate a Raman spectrum.

[0078] Figure 22 Another example of a spectrum collection method using an addressable 2-D laser array and an addressable 2-D array detector is shown. In one embodiment, for example, all lasers in the 2-D laser array are turned on except for one row that is turned off, and readout of rows of the detector array is performed along rows aligned with rows of the turned-off laser array.

[0079] Figure 23 An example of fluorescence removal by BDM (background decomposition method) is shown.

[0080] Figures 24 to 27 and Figure 29 An example spectral signal is shown.

[0081] Figure 27 An example of generating a Raman spectroscopy signal at a sample using 1064 nm and 785 nm excitation sources is shown. In this example, a fluorescence removal method is described that yields better performance using a 785 BDM under 1064 nm excitation.

[0082] Figure 28Illustrate the origin of fluorescence in Raman spectroscopy applications. The small arrow depicted as vibrational relaxation implies that fluorescence is independent of the excitation wavelength, while the Raman transient shifts with the laser wavelength. This difference provides the mathematical basis for the separation of fluorescence and Raman.

[0083] Hadamard transform to extract Raman spectra

[0084] In one embodiment, a mathematical operation such as the Hadamard transform can be used to extract Raman spectra from complex samples. In this embodiment, the idea is to reconstruct the entire sample illumination using the Hadamard patterns that produce different spatial components from the excitation laser pixels. This produces a differential Raman signal from each pattern associated with the different spatial distances at which a single pixel is excited.

[0085] An example of the transform is described in Zibang Zhang, Xueying Wang, Guoan Zheng, and Jingang Zhong, “Hadamard single-pixel imaging versus Fourier single-pixel imaging,” Optics Express, Vol. 25, No. 16, 19619-19639, August 7, 2017, which is incorporated herein in its entirety as if fully set forth herein.

[0086] HIS (Hadamard Single Pixel Imaging) is based on the Hadamard transform. HSI acquires the Hadamard spectrum of the object image and reconstructs the object image by applying the inverse Hadamard transform. The Hadamard spectrum consists of a set of Hadamard coefficients. Each coefficient corresponds to a unique Hadamard basis pattern. In order to obtain the Hadamard coefficients, the corresponding Hadamard basis pattern can be projected onto the object, and the resulting light intensity can be measured using a single-pixel detector. The single-pixel light intensity measurement is mathematically equivalent to the inner product between the Hadamard basis pattern and the object. Therefore, the Hadamard spectrum can be reconstructed based on the single-pixel measurement. The two-dimensional Hadamard transform H{}H{} of the image I(x,y)I(x,y) is defined as (1)

[0088]

[0089] (x,y)(x,y) is the coordinate in the spatial domain (2)

[0091] q(x,y,u,v)≡∑i=0n-1[gi(u)xi+gi(v)yi], q(x,y,u,v)≡∑i=0n-1[gi(u)xi+gi(v)yi],

[0092] where (u, v)(u, v) are coordinates in the Hadamard field, n = log2Nn = log2N, and (3)

[0094]

[0095] The terms uiui, vivi, xixi, and yiyi are the binary representations of uu, vv, xx, and yy, respectively. For example, (4)

[0097] (u) decimal = (un-1un-2…u1u0) binary. (u) decimal = (un-1un-2…u1u0) binary.

[0098] The Hadamard spectrum can be given a frequency interpretation - along each row / column of the Hadamard spectrum, the frequency is referred to as the number of changes of sign. However, since the Hadamard basis pattern is not strictly periodic, the word "sequential" is used to refer to the number of changes of sign

[38] . The Hadamard transform is only applicable to input images of size NN by NN, where NN, N / 12, N / 12, or N / 20 are powers of 2.

[0099] The Hadamard basis pattern PH(x,y)PH(x,y) can be obtained by applying the inverse Hadamard transform to the delta function δH(u,v)δH(u,v), (5)

[0101] PH(x,y)=12[1+H-1{δH(u,v)}], PH(x,y)=12[1+H-1{δH(u,v)}],

[0102] where H-1{}H-1{} represents the inverse Hadamard transform, and (6)

[0104] otherwise, Otherwise, δH(u,v)={1,u=u0,v=v00.

[0105] By substituting u=5u=5 and v=5v=5 into equation (5), we derive Figure 28 A sample Hadamard pattern is shown. Thus, it has 5 symbol changes per row and 5 symbol changes per column.

[0106] Differential HSI is an embodiment of HSI that allows each Hadamard coefficient H(u,v)H(u,v) to be obtained as a differential measurement. Differential HSI helps suppress noise. As illustrated in FIG30 , in order to obtain the coefficient H(u,v)H(u,v), differential HSI performs two measurements. One measurement is obtained by projecting the Hadamard pattern PH(x,y)PH(x,y), and the other measurement is obtained by its inverse [1-PH(x,y)][1-PH(x,y)]. The coefficient H(u,v)H(u,v) is obtained by using the following two corresponding measurements (7)

[0107] H(u,v)=D+1-D-1, H(u,v)=D+1-D-1,

[0108] where D+1D+1 and D-1D-1 are the measured values ​​corresponding to the illumination PH(x,y)PH(x,y) and [1-PH(x,y)][1-PH(x,y)], respectively. The Hadamard coefficients are real-valued, and the number of Hadamard coefficients is the same as the number of image pixels. Fully sampling an N×NN×N-pixel image using differential HSI requires 2N22N2 measurements.

Claims

1. A spectrometer comprising: a light source adapted to provide an excitation incident light beam; a detector adapted to detect a spectral signal; as well as an optical system adapted to direct the excitation incident light beam toward a sample, receive a spectral signal from the sample, and provide the spectral signal to the detector, The light source comprises a plurality of laser sources adapted to provide a plurality of excitation incident light beams through the optical system. 2 . The spectrometer of claim 1 , wherein the plurality of laser sources comprises a plurality of VCSEL laser sources. 3 . The spectrometer of claim 1 , wherein the plurality of laser sources of the light source comprises a two-dimensional array of laser sources. The spectrometer of claim 3 , wherein the two-dimensional array of laser sources comprises an array of VCSEL lasers. 5 . The spectrometer according to claim 1 , wherein the optical system is adapted to provide the plurality of excitation incident light beams to the sample and receive a plurality of spectral signals corresponding to the plurality of excitation incident light beams from the sample. The spectrometer of claim 1 , wherein the optical system is adapted to provide the plurality of excitation incident beams across a surface of the sample.

7. The spectrometer of claim 1, wherein at least a portion of the plurality of laser sources are addressable.

8. The spectrometer of claim 7, wherein each of the laser sources is individually addressable.

9. The spectrometer of claim 7, wherein at least two portions of the plurality of laser sources are individually addressable.

10. The spectrometer of claim 1, wherein the detector comprises a plurality of detector elements.

11. The spectrometer of claim 10, wherein the plurality of detector elements comprises a two-dimensional array of detector elements.

12. The spectrometer of claim 10, wherein at least a portion of the plurality of detector elements are addressable.

13. The spectrometer of claim 12, wherein each of the detector elements is individually addressable.

14. The spectrometer of claim 12, wherein at least two portions of the plurality of detector elements are individually addressable.

15. The spectrometer of claim 1, wherein the spectrometer comprises a controller adapted to process one or more detector signals from the detector.

16. The spectrometer of claim 15, wherein the controller is adapted to correct for curvature of the spectral signal at the detector.

17. The spectrometer of claim 16, wherein the controller is adapted to correct the curvature by fitting a circle to a known straight line.

18. The spectrometer of claim 15, wherein the controller is adapted to linearize the detected spectral signal received at the detector.

19. The spectrometer according to claim 1, wherein the optical system comprises a lens adapted to flatten an intensity distribution of the spectral signal at the detector.

20. The spectrometer of claim 1, wherein the detector comprises a plurality of detector elements adapted to detect a plurality of spectral signals corresponding to the plurality of excitation incident light beams.

21. The spectrometer of claim 20, wherein the spectrometer comprises a controller adapted to separate the spectra of the target material and the second material of the sample.

22. The spectrometer of claim 21, wherein the sample comprises an inhomogeneous sample.

23. The spectrometer of claim 21, wherein the second material comprises a surface of the sample.

24. The spectrometer of claim 1, wherein the optical system comprises a beam expander adapted to expand the plurality of excitation incident light beams at the surface of the sample.

25. A spectrometer comprising: a light source adapted to provide an excitation incident light beam; a detector adapted to detect a spectral signal; as well as an optical system adapted to direct the excitation incident light beam toward a sample, receive a spectral signal from the sample, and provide the spectral signal to the detector, Wherein the detector comprises a plurality of detector elements.

26. The spectrometer of claim 26, wherein the light source comprises a VCSEL laser source.

27. The spectrometer of claim 26, wherein the light source comprises a plurality of laser sources adapted to provide a plurality of excitation incident beams.

28. The spectrometer of claim 28, wherein the plurality of laser sources comprises a two-dimensional array of laser sources.

29. The spectrometer of claim 29, wherein the two-dimensional array of laser sources comprises an array of VCSEL lasers.

30. The spectrometer of claim 28, wherein the optical system is adapted to provide the plurality of excitation incident light beams to the sample and receive a plurality of spectral signals corresponding to the plurality of excitation incident light beams from the sample.

31. The spectrometer of claim 28, wherein the optical system is adapted to provide the plurality of excitation incident beams across a surface of the sample.

32. The spectrometer of claim 28, wherein at least a portion of the plurality of laser sources are addressable.

33. The spectrometer of claim 26, wherein the plurality of detector elements comprises a two-dimensional array of detector elements.

34. The spectrometer of claim 26, wherein at least a portion of the plurality of detector elements are addressable.

35. The spectrometer of claim 35, wherein each of the detector elements is individually addressable.

36. The spectrometer of claim 35, wherein at least two portions of the plurality of detector elements are individually addressable.

37. The spectrometer of claim 26, wherein the spectrometer comprises a controller adapted to process one or more detector signals from the detector.

38. The spectrometer of claim 38, wherein the controller is adapted to correct for curvature of the spectral signal at the detector.

39. The spectrometer of claim 39, wherein the controller is adapted to correct the curvature by fitting a circle to a known straight line.

40. The spectrometer of claim 38, wherein the controller is adapted to linearize the detected spectral signal received at the detector.

41. The spectrometer of claim 26, wherein the optical system comprises a lens adapted to flatten an intensity distribution of the spectral signal at the detector.

42. The spectrometer of claim 26, wherein the plurality of detector elements are adapted to detect a plurality of spectral signals corresponding to a plurality of excitation incident light beams.

43. The spectrometer of claim 43, wherein the spectrometer comprises a controller adapted to separate spectra of the target material and the second material of the sample.

44. The spectrometer of claim 44, wherein the sample comprises an inhomogeneous sample.

45. The spectrometer of claim 44, wherein the second material comprises a surface of the sample.

46. ​​The spectrometer of claim 26, wherein the optical system comprises a beam expander adapted to expand the plurality of excitation incident light beams at the surface of the sample.

47. A spectrometer comprising: a light source adapted to provide an excitation incident light beam; a detector adapted to detect a spectral signal; as well as an optical system adapted to direct the excitation incident light beam toward a sample, receive a spectral signal from the sample, and provide the spectral signal to the detector, The optical system includes a beam expander adapted to expand the excitation incident light beam.

48. A method for determining at least one spectrum of a sample, the method comprising: providing a plurality of excitation incident light beams from a light source comprising a plurality of light sources; directing the plurality of excitation incident light beams to a sample via an optical system; receiving a spectral signal from the sample via the optical system; as well as directing the spectral signal to a detector via the optical system; At least one spectrum corresponding to the spectral signal is determined.

49. The method of claim 49, wherein the operation of determining at least one spectrum is performed via a controller.

50. A method for determining at least one spectrum of a sample, the method comprising: providing an excitation incident beam from a light source; directing the excitation incident light beam to the sample via an optical system; receiving a spectral signal from the sample via the optical system; directing the spectral signal to a detector via the optical system, wherein the detector comprises a plurality of detector elements; as well as At least one spectrum corresponding to the spectral signal is determined.

51. The method of claim 49, wherein the operation of determining at least one spectrum is performed via a controller.

52. The method of claim 49, wherein the detector comprises a two-dimensional array of detector elements.

53. A method for determining at least one spectrum of a sample, the method comprising: providing an excitation incident beam from a light source; directing the excitation incident light beam to the sample via an optical system; expanding the excitation incident light beam within the optical system; receiving a spectral signal from the sample via the optical system; as well as directing the spectral signal to a detector via the optical system; At least one spectrum corresponding to the spectral signal is determined.

54. The method of claim 52, wherein the operation of determining at least one spectrum is performed via a controller.

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