Spectroscopic apparatus and spectroscopic method

Abstract

The Raman spectrometer comprises an optical input unit (16), optical selectors (32) and (33) configured to selectively determine a pair of optical systems (30a) and (34a) selected from different pairs, and a photodetector (24) configured to disperse the incident light received by the optical input unit (16) into a spectrum, and to detect the spectrum. When a different pair of optical systems (30a), (30b), (30c), (30d); (34a), (34b), (34c), (34d) is selected from the set, the spectrum that can be detected by the photodetector (24) changes.

Description

Technical Field

[0001] The present invention relates to a spectroscopic apparatus and a spectroscopic method. The present invention is applicable to, but not limited to, a specific spectroscopic apparatus that can be used over a wide range of wave numbers, resolutions, and dispersions such as Raman spectroscopy.

Background Art

[0002] The Raman effect is a phenomenon in which a sample scatters incident light of a specific frequency to generate a frequency spectrum, and characteristic peaks occur in this frequency spectrum due to the interaction between the incident light and the molecules constituting the sample. Since different molecular species have different characteristic Raman peaks, this effect can be used to analyze the existing molecular species.

[0003] Conventional Raman analyzers are described in Patent Document 1. A sample is irradiated with a laser beam, and the generated Raman scattered light is analyzed and detected. The detector can be a charge-coupled device (CCD) including a two-dimensional array of pixels. Analysis of the Raman spectrum can be performed by a dispersive device such as a diffraction grating that disperses the spectrum generated from a point or a line on the sample over the entire width direction of the CCD. The apparatus can be configured to widely disperse the spectrum over the entire width direction of the CCD in order to provide high spectral resolution.

[0004] However, with a CCD of a certain width, only a portion of the spectrum can be detected at once. To acquire data from a wider spectrum, it is possible to expose a portion of the spectrum to the CCD for a sufficient amount of time and read all the data associated with that portion of the spectrum from the CCD into a computer. Next, the diffraction grating is indexed to a new position, thereby allowing a second portion of the spectrum to be received by the CCD. Again, sufficient exposure time is ensured, and all the data from the second portion of the spectrum is read into the computer. This process can be repeated as many times as needed. Sequentially exposing individual portions of the spectrum increases the time required to analyze the entire spectrum compared to a low-resolution system where the entire spectrum of interest is narrowly dispersed across the width of the CCD.

[0005] Patent Document 1 describes a further data acquisition method in which, at a specific point in time, the Raman spectrum is distributed along a column or row of a CCD detector. The spectrum is scanned along the column or row of pixels in synchronization with the transfer of charge from pixel to pixel and the reading of data from the edge pixels to the computer. After a short exposure time, the computer instructs the CCD to transfer all the data one pixel at a time, and at the same time instructs the turntable to index the grid by an amount equivalent to the spectral resolution between adjacent pixels.

[0006] Next, after an even shorter exposure time of the same length as before, the charge from each pixel is transferred again to the adjacent pixels, and at the same time, the grid is re-indexed by an amount equivalent to the spectral resolution between adjacent pixels. This process is repeated many times to acquire data from as wide a spectral range as needed.

[0007] However, to investigate spectra at specific wavenumbers, the diffraction grating must be positioned at an extreme angle to the incident beam (close to 90° with respect to the grating's normal). This is undesirable because investigating the desired wavenumber range may require a very large diffraction grating and, in some cases, a CCD lens. For other wavenumber ranges, a very large angle to the output beam may be required, resulting in a very narrow beam that does not spread sufficiently across the CCD lens, compromising the quality of the focus. Other wavenumber ranges may not be obtainable at all.

[0008] Patent Document 2 describes a spectrometer in which the spectrum from a point at a line focus is distributed in rows on a CCD detector having a two-dimensional pixel array. The line focus moves vertically in the Y direction relative to the sample. Simultaneously and synchronously, the charge moves in a parallel direction Y' within the CCD, thereby continuously accumulating data from specific points in the sample. This ensures that the data from each sample point is generated from illumination integrated along the line focus, making it easier to then stitch the data together to form an image of the sample. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] European Patent Application Publication No. 0543578 [Patent Document 2] U.S. Patent No. 8179526 [Overview of the project]

[0010] According to a first aspect of the present invention, a spectrometer is provided comprising an optical input unit, an optical selector configured to selectively configure a pair of optical systems selected from different pairs so that the pair of optical systems disperse incident light received by the optical input unit into a spectrum, and a photodetector configured to detect the spectrum. Selecting different pairs of optical systems from the set may change the spectrum that can be detected by the photodetector (for the same incident light). The different spectrum may be a change in the wavenumber of the spectrum, a change in the resolution of the spectrum, and / or a change in the dispersion of the spectrum.

[0011] Using pairs of optical systems avoids the need for diffraction gratings defined at extreme angles, and selecting a pair allows the instrument to be used for a variety of purposes requiring detection of different wavenumbers and / or spectral detection with different resolutions and / or dispersions.

[0012] A photodetector may include an array of photodetectors. A pair of optical systems can disperse the spectrum across the entire array of photodetectors. A photodetector may include a two-dimensional array of photodetectors, and a pair of optical systems can disperse the spectrum across the entire rows or columns of the two-dimensional array.

[0013] The device includes a computer configured to receive individual data values ​​from a photodetector, which are recorded for different wavelengths of incident light simultaneously incident on different photodetectors of the photodetector, and each data value is associated with a different wavenumber.

[0014] This device includes a light source that generates an excitation beam for irradiating a sample, and the optical input is configured to receive Raman light generated from the irradiation of the sample with the excitation beam. This device includes a laser that generates a laser beam for irradiating a sample, and the optical input is configured to receive Raman light generated from the irradiation of the sample with the laser beam. This device may include a Rayleigh filter that removes the laser wavelength of the laser beam from the light sent to a pair of optical systems. Therefore, the spectrum may not include the laser wavelength.

[0015] The optical selector includes a first optical selector configured to selectively select a first optical system from a first set of different optical systems, and a second optical selector configured to selectively select a second optical system from a second set of different optical systems, forming a pair of optical systems for dispersing incident light received by an optical input into a spectrum. The first set of optical selectors and the second optical selector are mechanically independent, and selecting a first optical system from a first set of different optical systems can be performed independently of selecting a second optical system from a second set of different optical systems. The first and second optical selectors can be configured to form pairs of different optical systems by pairing one optical system from the first set of different optical systems with one of each of the multiple optical systems from the second set of different optical systems. Preferably, each first optical system can be paired with one of each of the corresponding multiple optical systems from the second set of optical systems. The corresponding multiple optical systems from the second set of optical systems may be the same as or different from each optical system in the first set of optical systems. In this way, by selecting different combinations of the first and second optical systems, different pairs of optical systems can be formed. Each optical system in the first set of different optical systems can be paired with each optical system in the second set of different optical systems. Therefore, many pairs (subsets) can be formed from the first and second sets of optical systems.

[0016] A first optical selector includes a first rotating mount for a first set of different optical systems, and when the first mount is rotated to different angular positions, one of the different optical systems is selectively positioned as the first optical system of the pair. A second optical selector includes a second rotating mount for a second set of different optical systems, and when the second mount is rotated to different angular positions, one of the different optical systems is selectively positioned as the second optical system of the pair. The first selector and / or the second selector may include a barrel roll optical mount for mounting multiple optical systems on a single stage.

[0017] The first and / or second rotary mounts can be configured to maintain the selected first / second optical system at one of several different angular positions with respect to the optical axis of the incident light. This configuration is suitable for several operating modes.

[0018] In the first operating mode, the first and second rotating mounts rotate synchronously, changing the angle of the first optical system with respect to incident light from the optical input and the angle of the second optical system with respect to light from the first optical system (shifting the central wavenumbers of the first and second optical systems), thereby altering a portion of the spectrum that strikes the photodetector. The photodetector may include rows or columns of photodetectors configured such that the spectrum moves along the rows or columns of photodetectors due to the synchronous movement of the first and second rotating mounts. The data accumulated in each photodetector is moved to the next photodetector in the row or column in synchronous with the movement of the rotating mounts, and data of a particular wavenumber is accumulated across multiple photodetectors. In this way, for a given pair of optical systems, the spectral range (wavenumber range) of the spectrum with a spatial range wider than the row / column width / length can be detected. This method may extend the spectral range detectable at a given resolution. In such a configuration, the row or column read registers / elements are located at the ends of the row or column, and the spectral values ​​(data) accumulated across the multiple photodetectors in the row or column can be gradually moved to the read registers in synchronization with the movement of the first and second rotary mounts.

[0019] In the second operating mode, the photodetector consists of rows or columns of photodetectors and readout registers / elements defined at the ends of the rows or columns, and the position of the image projected onto the photodetector of the optical profile used to illuminate the sample is adjusted relative to the readout registers / elements based on the length of the image on the photodetector in a direction perpendicular to the spectral direction. For example, if the optical profile is a spot, the center of the spot image may be positioned closer to the readout registers / elements (including within the readout registers / elements) in the photodetector than if the optical profile were a line focus (e.g., produced using a cylindrical lens). This optimizes the reading speed of the spot profile and reduces interference from stray light. The spectral direction is the direction in which the spectrum is dispersed throughout the photodetector.

[0020] The spectroscopic device may include a controller for controlling the first mount and the second mount, and in some embodiments, also for controlling the photodetector, to perform the first operating mode and / or the second operating mode.

[0021] The first set of different optical systems may be the same as or different from the second set of different optical systems. The first set of different optical systems may include at least one dispersive optical system, preferably a plurality of dispersive optical systems. The second set of different optical systems may include at least one dispersive optical system, preferably a plurality of dispersive optical systems. The dispersive optical system may include a diffraction grating.

[0022] The first set or the second set may include a mirror. Thus, when a mirror is selected, the spectrum is formed by the other (dispersive) optical system of the pair.

[0023] Each optical system of the pair may be a reflective optical system. The incident light moves from the light input part to the photodetector along a zigzag optical path, and each optical system of the pair is positioned at the corner of the zigzag optical path. The incident light may move between the pair of optical systems without passing through an aperture such as a slot or a pinhole. The incident light may move between the pair of optical systems without passing through a focusing optical system. The incident light may move between the pair of optical systems without passing through a focusing optical system that focuses the incident light onto an intermediate focusing surface of the aperture. It may not be necessary to position optical components on the optical path between the pair of optical systems.

[0024] The photodetector may be a CCD or a CMOS detector.

[0025] According to a second aspect, a method of controlling a spectroscopic device according to the first aspect of the present invention is provided. This method includes identifying a pair of optical systems selected from different pairs of sets, controlling an optical selector to configure the selected pair of optical systems such that the incident light received by the light input part is dispersed into a spectrum and sent to the photodetector, and detecting the spectrum with the photodetector.

[0026] The photodetector includes an array of photodetection elements, and a pair of optical systems disperses a spectrum over the entire array of photodetection elements. This method can include reading individual data values from the photodetector and reading data values recorded for different wavelengths of incident light that simultaneously impinge on different photodetection elements of the photodetector, and associating each data value with a different wave number. The different wave numbers associated with each data value are determined based on the selected optical system and the wave numbers of the spectrum that the selected optical system disperses over the entire photodetection elements when the data value is recorded.

[0027] Identifying the pair of selected optical systems may include receiving user input and identifying the pair of optical systems selected based on the user input. The user input can identify the spectrum of the photodetector and / or the required resolution and / or wave number range of the dispersion, and / or the wavelength of illumination light such as laser light used to irradiate a sample that generates (e.g., through inelastic scattering of illumination light) the incident light received by the light input section.

[0028] In this embodiment, the first optical selector includes a first rotation mount and a second rotation mount, and the method may include positioning the selected pair of optical systems and controlling the first rotation mount and the second rotation mount such that the selected pair of optical components disperses the incident light received by the light input section into a spectrum and irradiates the photodetector.

[0029] The method can include controlling the first rotation mount and / or the second rotation mount to change the angular position of the selected first / second optical system with respect to the optical axis of the incident light such that the spectrum is defined at a desired position on the photodetector.

[0030] This method may involve controlling a first and a second rotating mount to rotate synchronously, thereby shifting the central wavenumber of the first and second optical systems, and altering a portion of the spectrum that strikes the photodetector. The photodetector may include a row or column of photodetectors configured such that the spectrum moves along the row or column of photodetectors due to the synchronous movement of the first and second rotating mounts. This method may involve moving the data accumulated in each photodetector to the next photodetector in the row or column, in synchronization with the movement of the rotating mounts, so that data for a particular wavenumber is accumulated across multiple photodetectors. In this way, for a given pair of optical systems, the spectral range (wavenumber range) of the spectrum with a spatial range wider than the row / column width / length can be detected. Such a method may extend the spectral range detectable at a given resolution. In such a configuration, a row or column read register / element is located at the end of the row or column, and the spectral values ​​(data) accumulated across multiple photodetectors in the row or column can be gradually moved to the read register in synchronization with the movement of the first and second rotary mounts.

[0031] The photodetector may include rows or columns of photodetectors and readout registers / elements located at the ends of the rows or columns, and the method may include adjusting the position of the image projected onto the photodetector of the optical profile used to illuminate the sample relative to the readout registers / elements, based on the length of the photodetector image in a direction perpendicular to the spectral direction. For example, if the optical profile is a spot, the center of the spot image may be located on a photodetector closer to the readout registers / elements (including within the readout registers / elements) than if the optical profile is a line focus (e.g., produced using a cylindrical lens). This optimizes the reading speed of the spot profile and reduces interference from stray light.

[0032] According to a third aspect, a controller for a spectrometer according to a first aspect of the present invention is provided, which is configured to control the spectrometer in accordance with the method of a second aspect of the present invention.

[0033] According to a fourth aspect, a data carrier is provided which, when executed by a controller of a spectrometer such as the apparatus according to the first aspect of the present invention, causes the spectrometer to perform the method according to the second aspect of the present invention.

[0034] The data carrier may be a non-temporary data carrier (e.g., floppy disk, CD-ROM, DVD-ROM / RAM (including -R / -RW and +R / +RW), HD DVD, Blu-ray™ disc), memory (such as Memory Stick™, SD card, CompactFlash card), disk drive (such as hard disk drive), tape, any magnetic / optical storage, or a temporary data carrier (e.g., signals over wired or optical fiber, or wireless signals, such as signals transmitted over wired or wireless networks (such as Internet downloads, FTP transfers, etc.)).

[0035] A fifth aspect of the present invention provides a method for calibrating a spectrometer comprising an optical input unit, a first rotating mount for a first optical system, and a second rotating mount for a second optical system, wherein the pair of first and second optical systems includes a photodetector for dispersing incident light received by the optical input unit into a spectrum and detecting the spectrum. Rotation of the first mount adjusts the angular position of the first optical system with respect to the optical axis of the incident light from the optical input unit, and rotation of the second mount adjusts the angular position of the second optical system with respect to the light incident from the first optical system, and the method includes determining the wavenumber of the spectrum detectable by the photodetector for a plurality of relative angular positions of the first and second optical systems.

[0036] The first optical system may be a first diffraction grating, and the second optical system may be a second diffraction grating.

[0037] This method may include positioning the first optical system at a zero-order angular position such that zero-order incident light is directed towards the second optical system. Next, multiple different angular positions of the second optical system are calibrated by measuring the spectrum of a photodetector for each different angular position of the second optical system. From the measured spectra, a first set of physical parameters can be determined.

[0038] This method may include positioning a second optical system at a zero-order angular position where the zero-order light of the incident beam is directed towards the center of the photodetector. Next, multiple different angular positions of the first optical system are calibrated by measuring the spectrum of the photodetector for each different angular position of the first optical system. From these measured spectra, a second set of physical parameters can be determined.

[0039] This method may include determining the average set of physical parameters from the physical parameters of the first set and the second set.

[0040] The determined physical parameters may be (sufficiently) used to predict the wavenumber at each photodetector element of the photodetector for several predetermined angular positions of the first and second optical systems.

[0041] This method may include refining physical parameters determined by measuring the spectrum of a photodetector (e.g., generated using a calibration lamp) for a given set of angular positions of a first optical system and a second optical system, comparing the measured spectrum with a predicted spectrum predicted using the determined physical parameters, and refining the determined physical parameters based on the comparison. This comparison may be made between the predicted wavenumber of the photodetector and the measured wavenumber of the photodetector. The measured wavenumber may be based on a known spectrum generated by a calibration lamp.

[0042] A further aspect of the present invention provides a spectrometer comprising an optical input unit, a first rotating mount for a first optical system, and a second rotating mount for a second optical system. The pair of first and second optical systems disperse incident light received by the optical input unit into a spectrum. The spectrometer includes a photodetector for detecting the spectrum and a controller for controlling the movement of the first and second mounts, the controller being configured to rotate the first and second rotating mounts synchronously, thereby changing the angle of the first optical system with respect to the incident light from the optical input unit and the angle of the second optical system with respect to the light from the first optical system, thereby changing a portion of the spectrum incident on the photodetector. The photodetector includes a photodetector comprising rows or columns of photodetectors configured such that the spectrum moves along the rows or columns of photodetectors due to the synchronous rotation of the first and second rotating mounts. The controller can control the photodetector so that the data accumulated in each photodetector moves to the next photodetector in a row or column in sync with the rotation of the rotating mount, and so that data for a particular wavenumber is accumulated across multiple photodetectors.

[0043] A further aspect of the present invention provides a spectrometer comprising an optical input unit, a first rotating mount for a first optical system, and a second rotating mount for a second optical system. The pair of first and second optical systems disperses incident light received by the optical input unit into a spectrum. A photodetector for detecting the spectrum, included in the spectrometer, comprises rows or columns of photodetectors and readout registers / elements located at the ends of the rows or columns. The spectrometer also includes a controller for controlling the movement of the first and second mounts to determine, with respect to the readout registers / elements, the image projected onto the photodetector of the optical profile used to illuminate the sample, based on the length of the photodetector image in a direction perpendicular to the spectral direction.

[0044] For example, if the optical profile is a spot, the center of the spot image may be located on a photodetector closer to the readout register / element (including within the readout register / element) than if the optical profile were a line focus (e.g., generated using a cylindrical lens). This optimizes the readout speed of the spot profile and reduces interference from stray light.

[0045] The image length of a photodetector with different optical profiles can be determined by calibration. Optical profiles consist of a point focus and a line focus. A controller can control the movement of the first and second mounts based on a signal indicating the type of illumination profile being used. For example, a spectrometer can generate a signal based on the user's selection of a focusing lens.

[0046] A further aspect of the present invention provides a spectroscopic device comprising: an optical input unit; a first optical system installed or installable to disperse light received from the optical input unit into a first spectrum; a second optical system installed or installable to receive the first spectrum and disperse the first spectrum into a second spectrum; and a photodetector configured to detect the second spectrum.

[0047] The first optical system may be a first diffraction grating. The second optical system may be a second diffraction grating. The first optical system may be a reflective dispersion element. The second optical system may be a reflective dispersion element. The first optical system may be a reflective diffraction grating. The second optical system may be a reflective diffraction grating. The incident light travels along a Z-shaped optical path from the optical input to the photodetector, and each optical system in the pair is located at a corner of the Z-shaped optical path.

[0048] Optical components do not necessarily need to be placed in the optical path between the first optical system and the second optical system. [Brief explanation of the drawing]

[0049] [Figure 1] Figure 1 is a schematic diagram of a spectrometer according to one embodiment of the present invention. [Figure 2] Figure 2 is a schematic diagram of a portion of the optical train used to deliver light from the sample to the photodetector. [Figure 3a] Figure 3a is a perspective view of the rotating optical mount of the spectrometer from the first direction. [Figure 3b] Figure 3b is a perspective view of the rotating optical mount of the spectrometer from a second direction. [Figure 4] This is a schematic diagram illustrating a method for extending the detectable spectral range using a pair of diffraction gratings operating in a first mode of operation. [Figure 5] This is a schematic diagram using the device in the second operating mode. [Modes for carrying out the invention]

[0050] Referring to the drawings, the apparatus according to the present invention includes a Raman spectrometer connected to a computer 25 that accesses memory 29.

[0051] The Raman spectrometer includes an excitation beam light source, and in this embodiment, the input laser beam 10 is reflected by 90° by a dichroic filter 12 (referred to herein as a Rayleigh filter) positioned at 45° to the optical path. Alternatively, a holographic dichroic filter may be positioned at a low incident angle, for example, 10°. The laser beam then passes through an objective lens 16, which focuses the laser beam onto a spot at focal point 19 on the sample 18. The light is scattered by the sample at this illumination spot, focused by the objective lens 16, collimated into a parallel beam, and this parallel beam returns to the dichroic filter 12. The filter 12 rejects Rayleigh scattered light having the same frequency as the input laser beam 10 and transmits Raman scattered light. The Raman scattered light is then delivered to the spectral analyzer 20.

[0052] As will be described in more detail below with reference to Figure 2, the spectral analyzer 20 includes a dispersion element such as a diffraction grating. Light from the analyzer 20 is focused by a lens 22 onto a suitable photodetector 24. A photodetector array is preferred. In this embodiment, the detector 24 is a charge-coupled device (CCD) consisting of a two-dimensional array of pixels 28, and is connected to a computer 25 that acquires data from each pixel 28 and analyzes the data as needed. The analyzer 20 generates a spectrum that spreads in a line along the CCD 24.

[0053] Sample 18 can be mounted on an XY table (not shown) so that the focus 19 can be scanned across the entire sample in the X and Y directions, for example, under the control of a computer 25. Multiple spectra can then be collected, each corresponding to a different point in the sample. A map can then be generated based on the characteristics of the sample determined from the collected spectra.

[0054] The focal point 19 may be a point, a spot, or a line. A line focus may be formed using a cylindrical lens 16.

[0055] Referring to Figures 2 and 3, the objective lens 16 acts as an optical input for receiving light scattered / emitted from a sample as a result of spot or line-focus illumination of the sample. The spectral analyzer includes an optical selector 39 configured to selectively define a pair of optical systems 30, 34 selected from different pairs, so that the pair of optical systems disperse the incident light received by the optical input 16 into a spectrum directed toward the photodetector 24. In this embodiment, the optical selector 39 includes a first optical selector 32 configured to selectively define a first optical system 30 from a first pair of different optical systems 30a, 30b, 30c, 30d, and a second optical selector 33 configured to selectively define a second optical system 34 from a second pair of different optical systems 34a, 34b, 34c, 34d, forming a pair of optical systems for dispersing the incident light received by the optical input 16 into a spectrum. Figure 3 shows the four optical systems 30a, 30b, 30c, 30d and 34a, 34b, 34c, 30d for each set. However, it will be understood that each set may contain more than two optical systems. The optical selector shown in Figure 3 provides six optical system positions.

[0056] Referring to Figure 3, in this embodiment, each optical selector 32, 33 includes a rotating mount, and by rotating the mount to different angular positions around the first axis AA, a corresponding set of different optical systems 30a, 30b, 30c, 30d, 34a, 34b, 34c, 34d are selectively determined in the optical path from the optical input 16 to the photodetector 24. The rotating mount includes a support 35 mounted to rotate around the first axis AA, which provides a position for mounting the optical system. The support 35 has a regular polygonal cross-section (hexagonal in this embodiment) and has a surface that provides the position for the optical system. A motor 36 is configured to rotate the support 35 around the first axis AA.

[0057] The support 35 is mounted on a base 37 so as to rotate. A motor (not shown) is built into the base 37 for rotating the support 35 around the second axis BB. The second axis BB is perpendicular to the first axis AA.

[0058] The first set of optical systems includes multiple diffraction gratings 30a, 30b, and 30c, each having a different lattice constant, and a mirror 39d. The second set of optical systems includes multiple diffraction gratings 34a, 34b, 34c, and 30d, each having a different lattice constant.

[0059] When in use, the first optical selector 32 is configured in the apparatus such that one of the diffraction gratings 30a, 30b, 30c or a mirror 30d receives light from the optical input section 16, disperses or reflects the light, and directs the dispersed / reflected light to the optical system 34a, 34b, 34c, 34d of the second optical selector 33. The second optical selector 33 may be configured in the apparatus such that one of the diffraction gratings 34a, 34b, 34c, 34d receives the dispersed / reflected light from the optical system 30a, 30b, 30c, 30d of the first optical selector 33 and corrects the dispersion of the dispersed light so that it is directed to the photodetector 24. The dispersed light from the optical system 34a, 34b, 34c, 34d of the second optical selector 33 is focused to the photodetector 24 by the lens 22. The pair of the first optical system 30 and the second optical system 34 forms a Z-shaped optical path from the lens 16 of the optical input section 16 to the output lens 22 of the photodetector 24.

[0060] Motors 36 and 37 are controlled by a controller 38. When in use, the controller 38 receives an input indicating the resolution and / or wavenumber of the spectrum detected by the photodetector 24. Based on the indicated resolution and / or wavenumber, the controller drives the motors 36 of each optical selector 32 and 33 to position the required optical systems 30a, 30b, 30c, 30d, 34a, 34b, 34c, and 34d in the optical path, forming pairs of first and second optical systems for dispersing light into the spectrum, so that the required wavenumber of the spectrum with the required resolution is collected by the photodetector 24. Based on the indicated resolution and / or wavenumber, the controller 38 can use a lookup table to determine the required optical systems 30a, 30b, 30c, 34a, 34b, and 34c. Alternatively, the user can input the required optical systems 30a, 30b, 30c, 34a, 34b, and 34c to the controller 38. Resolution and / or wavenumber and / or dispersion can be selected based on what is best suited to the spectroscopic application.

[0061] Furthermore, for each pair of optical systems 30a, 30b, 30c, 30d, 34a, 34b, 34c, 34d, the angle of the diffraction gratings 30a, 30b, 30c, 34a, 34b, 34c, 30d relative to the incident light can be adjusted using the motor 37, thereby providing various combinations of additive and subtractive variances using non-zero-order (-3, -2, -1, +1, +2, +3, etc.) or zero-order positions. This further increases the wavenumber range and resolution of the spectrum of the photodetector 24. The non-zero-order or zero-order position of the first optical system is the position where the first optical system directs incident light of its order to the second optical system. The non-zero-order or zero-order position of the second optical system is the position where the second optical system directs incident light of its order to the photodetector 24.

[0062] Furthermore, a wavelength-specific diffraction grating may be provided to allow for the selection of the diffraction grating based on the target wavenumber, thereby optimizing the diffraction efficiency.

[0063] Computer 25 is programmed with software code in a suitable medium such as memory 29, which contains instructions. When an instruction is executed by the processor of computer 25, computer 25 analyzes the data from the photodetector 24. Alternatively, the obtained Raman spectral data can be transferred to another computer equipped with software for this analysis. In either case, computer 25 receives information about the optical system selected by the first optical selector 32 and the second optical selector 33, and generates spectral data so that the analysis correctly reduces the intensity values ​​to the appropriate wavenumbers. The determined intensity values ​​are stored in the relevant computer, further processed, and output or displayed to show the concentration of the components in the sample(s)(s)(s)(plural).

[0064] Referring to Figure 4, the photodetector 24 includes a two-dimensional array of photodetectors 28 and a readout register 27. In one embodiment, the photodetector 24 is oriented such that the readout register is located at the end of a row or column in the spectral direction S (the direction in which the spectrum is dispersed by the pair of optical systems 30a, 30b, 30c, 30d; 34a, 34b, 34c, 34d). The direction perpendicular to the spectral direction S is the spatial direction D. In the case of a line focus 40, spectra are generated over each row / column in the spectral direction S in the photodetector 24 for different predetermined regions of the line focus 40. In the case of a point focus, spectra may be generated only over fewer rows / columns of the photodetector 24 in the spectral direction S, such as a single row / column of the photodetector 24. During use, the first optical selector 32 and the second optical selector 33 move synchronously around the second axis BB, changing the angle in the optical path of each selected optical system 30a, 30b, 30c, 30d, 34a, 34b, 34c, 34d to shift the central wavenumber of each grating, thereby changing the wavenumber of the spectrum hitting the photodetector 24. Synchronized with this spectral shift of the photodetector 24, the charge held by each photodetector element 28 is moved to another photodetector element 28 located in the spectral direction S toward the readout register 27. The charge is moved (measured) in synchronous with the spectral movement in the photodetector 24, thereby continuously accumulating the charge of a specific wavenumber collected by the first photodetector element in the different photodetector elements 28 of the photodetector 24. Once the accumulated data for a specific wavenumber is moved to the readout register 27, it is read out to the computer 25. In the case of a line focus, multiple values ​​for each wavenumber are read corresponding to different spatial positions along the line focus 40. In the case of a point focus, one value can be read for each wavenumber. This method extends the spectral range detectable at a specific resolution using specific optical system pairs 30a, 30b, 30c, 30d, 34a, 34b, 34c, and 34d, without the need to stitch together separately acquired spectral ranges.

[0065] Referring to Figure 5, in an alternative embodiment, the photodetector 24 is oriented such that the readout register 27 is located at the end of a row or column in the spatial direction D. The direction perpendicular to the spatial direction D is the spectral direction S. For a line focus 40, each selected optical system 30a, 30b, 30c, 30d, 34a, 34b, 34c, 34d is positioned around the first axis AA such that the end of the line focus is located at the readout register 27. For a point focus, the positions of each selected optical system 30a, 30b, 30c, 30d, 34a, 34b, 34c, 34d are adjusted around the first axis AA such that the spatial center of the image is located at the readout register 27. Thus, the readout speed is improved compared to not adjusting the spatial center position of the focus when switching between line focus and point focus.

[0066] In both of the methods described above, the apparatus needs to be calibrated for different angular positions of each rotating mount around axis AA and axis BB. Calibration around axis AA establishes the spatial position of the focal point in the photodetector at different angular positions of the rotating mount around axis AA. Calibration around axis BB establishes the wavenumber of the photodetector in the spectral direction at different angular positions of the rotating mount around axis BB. These calibrations can be performed by irradiating the optical input unit 16 with laser light and determining the position of the laser spot of the photodetector 24.

[0067] The first of the diffraction gratings 30a, 30b, and 30c is positioned at an angular position with respect to the optical path of the incident light such that the zero-order light is directed to the second optical system 34a, 34b, 34c, and 34d, which are selected along the optical path. The zero-order positions of the diffraction gratings 30a, 30b, and 30c can first be determined by orienting the diffraction grating so that the incident light is reflected straight back to the optical input section 16. From this position, rotating the diffraction grating by an angle (15° in this embodiment) corresponding to a known angle from the incident light to the optical path between the first and second optical systems will direct the zero-order light approximately to the second optical system. Alternatively, a target may be defined along the path between the first and second optical systems, and this method involves detecting when the zero-order light of the incident light is directed to the target. The incident light may be a laser beam. This process is repeated for each of the diffraction gratings 30a, 30b, and 30c of the first optical selector 32, thereby determining the position of each diffraction grating 30a, 30b, and 30c so that it directs zero-order light along the optical path to the selected second optical system 34a, 34b, 34c, and 34d.

[0068] Next, the zero-order positions of each diffraction grating 34a, 34b, 34c, and 34d of the second optical selector 33 are determined. The diffraction gratings 30a, 30b, and 30c are positioned so that the zero-order light of the incident light is directed towards the diffraction gratings 34a, 34b, 34c, and 34d, and the positions of the diffraction gratings 34a, 34b, 34c, and 34d with respect to the incident light are adjusted until the zero-order light of the light is directed towards the center of the photodetector 24.

[0069] Next, the spectral movement of the photodetector 24 in the spectral direction S can be calibrated as a result of rotating the diffraction grating around axis BB. A calibration light source, such as a neon light, is used to generate light with a known spectrum that has clearly defined emission lines. This light is received by the optical input unit 16. One of the first diffraction gratings and the second diffraction gratings 30a, 30b, 30c, 34a, 34b, 34c, 34d is rotated to different positions to move the known spectrum of the photodetector 24, while the other of the first diffraction gratings and the second diffraction gratings 30a, 30b, 30c, 34a, 34b, 34c, 34d is maintained in the zero-order position. Intensity values ​​from the photodetector elements at each position are recorded, and the change in wavenumber (wavenumber / pixel) for rotation of the diffraction gratings 30a, 30b, 30c, 34a, 34b, 34c, 34d is determined. This is repeated for multiple positions of diffraction gratings 30a, 30b, 30c, 34a, 34b, 34c, and 34d, and for different positions of diffraction gratings 30a, 30b, 30c, 34a, 34b, 34c, and 34d of optical selectors 32 and 33. This process is repeated except for diffraction gratings 34a, 34b, 34c, 34d, 30a, 30b, and 30c of the other optical selectors 32 and 33. From the wavenumber changes, a set of physical parameters of the spectral system is fitted. This results in some physical parameters being overfitted because some physical features, such as lens distortion and focal length, appear differently in each calibration. Therefore, a mean set of physical parameters can be determined from the physical parameters found. This mean set of physical parameters can be used to predict the wavenumber of a specific pixel at a specific angular position of each diffraction grating 30a, 30b, 30c, 34a, 34b, 34c, and 34d.

[0070] Using the average set of physical parameters, the composite grating system can be calibrated to determine the final (refined) set of physical parameters. This can be done by recording spectra in the photodetector 24 at different positions on each pair of diffraction gratings 30a, 30b, 30c, 34a, 34b, 34c, and 34d. The spectra can be created using a calibration lamp.

[0071] It will be understood that modifications and changes can be made to the above embodiments without departing from the scope of the invention as defined herein. For example, the rotation of the support 35 around the first and / or second axis may not be motorized. The second optical selector 33 may include a mirror instead of the first optical selector 32. The optical selector may include a single rotation axis BB instead of two rotation axes, and the multiple optical components 30a, 30b, 30c, 30d, 34a, 34b, 34c, 34d are mounted around axis BB, and the rotation of the optical component support around axis BB changes the optical components 30a, 30b, 30c, 30d, 34a, 34b, 34c, 34d in the optical path. The optical system can also be modified using a motorized linear mechanism. The rotation around BB sets the angle of the optical system with respect to the incident light. A potential drawback of an optical selector with a single rotation axis is that the position of the photodetector image for line focus and point focus cannot be changed to improve data acquisition rate.

Claims

1. Optical input section, A light selector configured to selectively determine a pair of optical systems selected from different pairs of optical systems, the pair of optical systems dispersing the incident light received by the light input into a spectrum, A photodetector configured to detect the spectrum and Includes, A Raman spectrometer that changes the spectrum detectable by the photodetector by selecting a different pair of optical systems from the aforementioned set.

2. The Raman spectrometer according to claim 1, wherein the incident light moves between the pair of optical systems without passing through a focusing optical system that focuses the incident light onto an intermediate focusing surface of an aperture.

3. The photodetector includes an array of photodetectors, The Raman spectrometer according to claim 1 or 2, wherein the pair of optical systems disperses the spectrum across the entire array of the photodetector elements.

4. Includes a computer configured to receive individual data values ​​from the aforementioned photodetector, The Raman spectrometer according to claim 3, wherein the data values ​​are recorded for different wavelengths of incident light simultaneously incident on different photodetectors of the photodetector, and each data value is associated with a different wavenumber.

5. Includes a light source that generates an excitation beam for irradiating the sample, The Raman spectrometer according to any one of claims 1 to 4, wherein the optical input unit is configured to receive Raman light generated from the irradiation of the sample with the excitation beam.

6. Includes a laser that generates a laser beam for irradiating the sample, The Raman spectrometer according to any one of claims 1 to 4, wherein the optical input unit is configured to receive Raman light generated from the irradiation of the sample with the laser beam.

7. The Raman spectrometer according to claim 6, further comprising a Rayleigh filter for removing the laser wavelength of the laser beam from the light delivered to the pair of optical systems.

8. The Raman spectrometer according to claim 6 or claim 7, wherein the spectrum does not include the laser wavelength.

9. The Raman spectrometer according to any one of claims 1 to 8, wherein the change in the spectrum includes a change in the wavenumber of the spectrum and / or a change in the resolution of the spectrum and / or a change in the dispersion of the spectrum.

10. The optical selector includes a first optical selector configured to selectively determine a first optical system from a first set of different optical systems, A second optical selector configured to selectively determine a second optical system from a second set of different optical systems, and A Raman spectrometer according to any one of claims 1 to 9, comprising, and forming the pair of optical systems for dispersing the incident light received by the optical input unit into the spectrum.

11. The Raman spectrometer according to claim 10, wherein the first optical selector and the second optical selector are configured to form different pairs of optical systems by pairing an optical system from the first set of different optical systems with each of the plurality of optical systems from the second set of different optical systems.

12. The Raman spectrometer according to claim 10 or 11, wherein the first optical selector and the second optical selector are configured such that each optical system of the first set of different optical systems is paired with each optical system of the second set of different optical systems.

13. The Raman spectrometer according to any one of claims 10 to 12, wherein the first optical selector includes a first rotating mount for the first set of different optical systems.

14. The Raman spectrometer according to claim 13, wherein the first rotating mount is configured to selectively determine one of the optical systems as the first optical system of the pair of optical systems by rotating the first mount to different angular positions.

15. The Raman spectrometer according to claim 13 or 14, wherein the first rotating mount is configured to maintain the selected first optical system at one of a plurality of different angular positions with respect to the optical axis of the incident light.

16. The Raman spectrometer according to any one of claims 1 to 15, wherein the second optical selector includes a second rotating mount for a second set of different optical systems.

17. The Raman spectrometer according to claim 16, wherein the second rotating mount is configured to selectively determine one of the optical systems as the second optical system of the pair of optical systems by rotating the second mount to different angular positions.

18. The Raman spectrometer according to claim 17 or 18, wherein the second rotating mount is configured to maintain the selected second optical system at one of a plurality of different angular positions with respect to the optical axis of the incident light.

19. The second optical selector includes a second rotating mount for the second set of different optical systems, the second rotating mount being configured to maintain the selected second optical system at one of a plurality of different angular positions with respect to the optical axis of the incident light. The Raman spectrometer according to claim 15, wherein the spectrometer includes a controller for controlling the first mount and the second mount.

20. The Raman spectrometer according to claim 19, characterized in that the controller controls the first rotary mount and the second rotary mount to rotate synchronously, and changes the angle of the first optical system with respect to incident light from the optical input and the angle of the second optical system with respect to light from the first optical system, thereby changing a portion of the spectrum that strikes the photodetector.

21. The Raman spectrometer according to claim 20, characterized in that the photodetector includes a row or column of photodetectors configured such that the spectrum moves along the row or column of photodetectors due to the synchronous movement of the first and second rotating mounts.

22. The Raman spectrometer according to claim 21, wherein the controller is configured to control the photodetector so that the data accumulated in each photodetector is moved to the next photodetector in the row or column in synchronization with the movement of the rotating mount, and data of a specific wavenumber is accumulated across a plurality of photodetectors.

23. The Raman spectrometer according to claim 19, wherein the photodetector comprises rows or columns of photodetectors and readout registers / elements positioned at the ends of the rows or columns, and the controller is configured to control the first and second rotating mounts to adjust the position of the image projected onto the photodetector of the optical profile used to illuminate the sample with respect to the readout registers / elements, based on the length of the image of the photodetector in a direction perpendicular to the spectral direction.

24. The Raman spectrometer according to claim 23, wherein the controller is configured to control the first and second rotary mounts such that, when the optical profile is a spot, the center of the image of the spot is positioned closer to the photodetector than when the optical profile is a line focus.

25. The Raman spectrometer according to any one of claims 1 to 24, characterized in that the different optical systems of the first set are the same as the different optical systems of the second set.

26. The Raman spectrometer according to any one of claims 1 to 24, characterized in that the different optical systems of the first set are different from the different optical systems of the second set.

27. The Raman spectrometer according to any one of claims 1 to 26, characterized in that the first set of different optical systems includes at least one dispersive optical system.

28. The Raman spectrometer according to claim 27, characterized in that the first set of different optical systems includes a plurality of dispersed optical systems.

29. The Raman spectrometer according to any one of claims 1 to 28, characterized in that the second set of different optical systems includes at least one dispersive optical system.

30. The Raman spectrometer according to claim 29, wherein the second set of different optical systems includes a plurality of dispersed optical systems.

31. The Raman spectrometer according to claim 29, wherein the dispersed optical system includes a diffraction grating.

32. The Raman spectrometer according to any one of claims 1 to 31, wherein the first set or the second set includes mirrors.

33. The Raman spectrometer according to any one of claims 1 to 32, characterized in that the incident light travels along a Z-shaped optical path from the optical input unit to the photodetector, and each of the pair of optical systems is positioned at the corner of the Z-shaped optical path.

34. Includes a pair of optical systems selected from the aforementioned different pairs, The optical selector is controlled so that the selected pair of optical systems is positioned by dispersing the incident light received by the optical input unit spectrally onto the photodetector. The spectrum is detected by the aforementioned photodetector. A method for controlling a Raman spectrometer according to any one of claims 1 to 33.

35. The aforementioned photodetector includes an array of photodetectors, The pair of optical systems disperses the spectrum throughout the entire array of the photodetector elements, and The method involves reading individual data values ​​from the photodetector, wherein the data values ​​are recorded for different wavelengths of incident light simultaneously incident on different photodetectors of the photodetector. Associating each data value with a different wave frequency. The method according to claim 34, which includes the following.

36. The method according to 35, characterized in that the different wavenumbers associated with each data value are based on the selected optical system and the wavenumbers of the spectrum that the selected optical system disperses across the entire photodetector when the data value is recorded.

37. The optical selector includes a first optical selector including a first rotating mount and a second optical selector including a second rotating mount. The method according to any one of claims 34 to 36, further comprising controlling the first rotating mount and the second rotating mount to disperse the incident light received by the optical input unit into a photodetector in a spectral state using the selected pair of optical systems.

38. The method according to claim 37, comprising controlling the first rotating mount and / or the second rotating mount to change the angular position of the selected first optical system / second optical system with respect to the optical axis of the incident light so that the spectrum is positioned at a desired position on the photodetector.

39. The method according to claim 38, comprising rotating the first rotating mount and the second rotating mount in synchronous motion to shift the central wavenumber of the first optical system and the second optical system, and thereby changing a portion of the spectrum that strikes the photodetector.

40. The method according to claim 39, wherein the photodetector includes a row or column of photodetectors configured such that the spectrum moves along the row or column of photodetectors by the synchronous movement of the first and second rotating mounts.

41. The method according to claim 40, comprising moving the data accumulated in each photodetector to the adjacent photodetector in the row or column in synchronization with the movement of the rotating mount, so that data relating to a specific wavenumber is accumulated across a plurality of photodetectors.

42. The photodetector includes rows or columns of photodetectors and read registers / elements positioned at the ends of the rows or columns, The method according to any one of claims 34 to 41, further comprising adjusting the position of the image projected onto the photodetector of the light profile used to illuminate a sample with respect to the readout register / element, based on the length of the image on the photodetector in a direction perpendicular to the spectral direction.

43. A controller for a Raman spectrometer according to a first aspect of the present invention, the controller configured to control the Raman spectrometer according to the method described in any one of claims 34 to 42.

44. A data carrier having an instruction, when executed by the controller of a Raman spectrometer, to cause the Raman spectrometer to perform the method described in any one of claims 34 to 42.

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