Spectroscopic device, Raman spectroscopic measurement device, and spectroscopic method

Abstract

This spectroscopic device (5) receives light (L1) wavelength-decomposed in a predetermined direction by a spectroscopic optical system (4) including a spectroscopic element and outputs spectroscopic spectral data of the light (L1), and is provided with: a pixel unit (11) having a plurality of pixels (21) that receive the wavelength-decomposed light (L1) and convert the wavelength-decomposed light (L1) into an electric signal; the plurality of pixels (21) are arranged in a row direction along a wavelength decomposition direction and a column direction perpendicular to the row direction. A conversion unit (12) that converts the electrical signals from the plurality of pixels (21) to the number of photons; and a generation unit (13) that integrates the number of photons of a plurality of pixels (21) belonging to the same column, and generates spectral data based on the result of the integration.

Description

Technical Field

[0001] The present disclosure relates to a spectroscopic device, a Raman spectrometric measurement device and a spectroscopic method. Background Art

[0002] As an existing spectroscopic device, there is a spectroscopic device described in Patent Document 1, for example. This existing spectroscopic device is a so-called Raman spectroscopic device. The spectroscopic device includes: a mechanism for linearly irradiating excitation light; a movable stage on which a sample is placed; an objective lens that focuses Raman light from an area irradiated with excitation light; a narrow slot that is provided at an imaging position of the Raman light; a spectrometer that disperses light passing through the narrow slot; a CCD detector that detects a Raman spectrum image; and a control device that controls positioning measurement by synchronizing the movable stage with the CCD detector. Prior art literature Patent Literature

[0003] Patent Document 1: Japanese Patent Application Publication No. 2016-180732 Summary of the invention The problem the invention is intended to solve

[0004] In the field of spectrometry that requires high sensitivity and high precision, such as Raman spectroscopy, fluorescence spectroscopy, and plasma spectroscopy, vertical binning of CCD image sensors is used when obtaining spectroscopic spectrum data in order to improve the signal-to-noise ratio. Vertical binning in CCD image sensors divides the charges generated in each pixel into multiple poles and adds them together. In CCD image sensors, read noise is only generated in the final amplifier and does not increase during the vertical binning process. Therefore, the more the number of vertical binning stages increases, the higher the signal-to-noise ratio can be.

[0005] As image sensors, CMOS image sensors are also known in addition to CCDs. However, at present, the popularity of CMOS image sensors has not progressed in the field of spectrophotometry that requires high sensitivity and high precision. In CMOS image sensors, an amplifier is configured in each pixel to convert the charge into a voltage for each pixel. In the case of vertical merging in existing CMOS image sensors, the more the number of vertical merging stages increases, the more the readout noise is accumulated, so there is a problem that the SN ratio of the signal is lower than when using a CCD image sensor.

[0006] The present disclosure has been made to solve the above-mentioned problems, and an object of the present disclosure is to provide a spectroscopic device, a Raman spectrometry device, and a spectroscopic method that can acquire spectroscopic spectrum data with an excellent SN ratio. Technical means of solving problems

[0007] The gist of a spectrometer, a Raman spectrometry device, and a spectrometry method according to one embodiment of the present disclosure is as follows [1] to

[12] .

[0008] [1] A spectroscopic device that receives light decomposed by wavelength in a predetermined direction through a spectroscopic optical system including a spectroscopic element and outputs spectroscopic spectrum data of the light, and comprises: a pixel unit having a plurality of pixels that receive the light decomposed by wavelength and convert the light into electrical signals, wherein the plurality of pixels are arranged in a row direction along the wavelength decomposition direction and in a column direction perpendicular to the row direction; a conversion unit that converts the electrical signals from the plurality of pixels into the number of photons; and a generation unit that integrates the number of photons of the plurality of pixels belonging to the same column and generates spectroscopic spectrum data based on the integration result.

[0009] In the spectroscopic device, the electrical signal output from each pixel is converted into the number of photons based on the light received by each pixel constituting the pixel unit. When converting from the electrical signal to the number of photons, for example, the number of photons of a pixel that has not received light is zero. Therefore, when the number of photons of a plurality of pixels belonging to the same column is integrated after conversion to the number of photons, the influence of the readout noise of each pixel can be sufficiently reduced. Therefore, in the spectroscopic device, the spectroscopic spectrum data can be obtained with an excellent SN ratio.

[0010] [2] The spectroscopic device of [1] further comprises a specific unit that specifies pixels used for photon number integration among a plurality of pixels belonging to the same column. In this case, by specifying pixels suitable for photon number integration, the influence of readout noise of each pixel can be further reduced. By reducing the influence of readout noise of each pixel, the conversion accuracy from the electrical signal to the photon number is improved, and the SN ratio of the spectroscopic spectrum data is further improved.

[0011] [3] A spectroscopic device as in [2], wherein pixels whose readout noise is below a threshold value are used as pixels for photon number integration. Thus, the influence of the readout noise of each pixel can be further reduced. By reducing the influence of the readout noise of each pixel, the accuracy of conversion from electrical signals to photon numbers is improved, and the SN ratio of the spectroscopic spectrum data is further improved.

[0012] [4] A spectroscopic device as in [3], wherein the threshold of the read noise is set to 0.3[e - rms]. As a result, the error conversion rate when converting the electrical signal into the number of photons can be suppressed to 10% or less.

[0013] [5] A spectroscopic device as in any one of [2] to [4], wherein the specific unit specifies pixels for photon number integration in such a manner that the number of pixels for photon number integration is the same in each column. In this case, the integrated value of the readout noise of the pixels in each column for photon number integration can be made consistent with respect to the row direction. Therefore, the SN ratio of the spectroscopic spectrum data can be stably improved.

[0014] [6] A spectroscopic device as described in any one of [2] to [5], wherein the specific unit specifies pixels for integrating the number of photons and the integration ratio of the pixels based on the aberration information of the light in the spectroscopic optical system, and the generating unit integrates the number of photons of the plurality of pixels using the integration ratio. According to this structure, even when distortion due to aberration occurs in the image of the light decomposed by wavelength, the number of photons of the plurality of pixels can be appropriately integrated.

[0015] [7] A spectroscopic device as in any one of [2] to [6], wherein the specific unit has in advance regional information indicating a region where no light is input in the pixel unit, and pixels corresponding to the regional information are excluded from the accumulation of the number of photons. In this case, by excluding pixels for which unnecessary photon counts are accumulated, the influence of readout noise of each pixel can be further reduced.

[0016] [8] The spectroscopic device according to any one of [1] to [7], wherein the conversion unit comprises: a first conversion unit that converts the electrical signal into a digital value; and a second conversion unit that converts the digital value into the number of photons based on pre-stored reference data. In this case, the number of photons of each pixel can be obtained while suppressing the influence of the deviation of the gain and offset of each pixel.

[0017] [9] The spectroscopic device according to any one of [1] to [8], further comprising an analysis unit for analyzing the spectroscopic spectrum data. In this case, the spectroscopic device is provided with a function for analyzing the spectroscopic spectrum data, thereby improving convenience.

[0018]

[10] The spectroscopic device according to any one of [1] to [9], further comprising a spectroscopic optical system including a spectroscopic element for splitting light along a wavelength separation direction. In this case, the spectroscopic device is provided with a wavelength separation function of light, thereby improving convenience.

[0019]

[11] A Raman spectrometry device comprising: a spectrometer according to any one of [1] to

[10] ; a light source unit that generates light to be irradiated onto a sample; and a light guiding optical system that guides Raman scattered light generated by irradiating the sample with the light to the spectrometer.

[0020] In the Raman spectrometry device, based on the Raman scattered light received by each pixel constituting the pixel unit, the electrical signal output from each pixel is converted into the number of photons. When converting from the electrical signal to the number of photons, for example, the number of photons of a pixel that does not receive the Raman scattered light is zero. Therefore, when the number of photons of a plurality of pixels belonging to the same column is integrated after conversion to the number of photons, the influence of the readout noise of each pixel can be sufficiently reduced. Therefore, in the Raman spectrometry device, the spectroscopic spectrum data of the Raman scattered light can be obtained with an excellent SN ratio.

[0021]

[12] A spectroscopic method, which receives light decomposed by wavelength along a specified direction and obtains spectroscopic spectrum data of the light, and comprises: a light receiving step, in which a plurality of pixels arranged in a row direction along the wavelength decomposition direction and in a column direction perpendicular to the row direction receive the light decomposed by wavelength and convert it into an electrical signal; a conversion step, in which the electrical signal from the plurality of pixels is converted into a photon number; and a generation step, in which the photon numbers of the plurality of pixels belonging to the same column are integrated and the spectroscopic spectrum data is generated based on the integrated result.

[0022] In this spectroscopic method, the electrical signal output from each pixel is converted into the number of photons based on the light received by each pixel. When converting from the electrical signal to the number of photons, for example, the number of photons of a pixel that has not received light is zero. Therefore, when the number of photons of multiple pixels belonging to the same column is integrated after conversion to the number of photons, the influence of the readout noise of each pixel can be fully reduced. Therefore, in this spectroscopic method, spectroscopic spectrum data can be obtained with an excellent SN ratio. Effects of the Invention

[0023] According to the present disclosure, spectroscopic spectrum data can be acquired with an excellent SN ratio. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a block diagram showing the structure of a Raman spectrometer according to one embodiment of the present disclosure. Figure 2 : is a diagram showing the structure of an imaging sensor. Figure 3 It is a graph showing the relationship between the number of electrons and the probability density. Figure 4 (a) and Figure 4 (b) is a diagram showing an example of conversion from an analog value to a digital value. Figure 5 Schematic diagram showing the process of obtaining an offset value. Figure 6 It is a schematic diagram showing the process of obtaining gain. Figure 7 Schematic diagram showing the corresponding relationship between gain and offset value and threshold value. Figure 8 is a diagram schematically showing a process of converting the digital value of each pixel into the number of electrons. Fig. 9 Schematic diagram showing an example of a readout noise map in a pixel portion. Fig.10 This is a diagram showing the relationship between read noise and the misconversion rate when an electrical signal is converted into the number of photons. Fig.11 (a) is a schematic diagram showing an example of a spectral image with aberration. Fig.11 (b) shows that based on Fig.11 Schematic diagram of an example of spectral spectrum data obtained by using the spectral spectrum image shown in (a). Fig.12 It is a schematic diagram showing an example of an integration ratio diagram in a pixel portion. Fig.13 is a schematic diagram showing spectroscopic spectrum data obtained by vertical binning using an integrated ratio graph. Fig.14 1 is a flowchart showing a spectroscopic method according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0025] Hereinafter, preferred embodiments of a spectroscopic device and a Raman spectrometry device according to one aspect of the present disclosure will be described in detail with reference to the drawings.

[0026] Figure 1 1 is a block diagram showing the structure of a Raman spectrometer according to an embodiment of the present disclosure. The Raman spectrometer 1 is a device for measuring the physical properties of a sample S using Raman scattered light Lr. In the Raman spectrometer 1, light L1 from a light source unit 2 is irradiated onto the sample S, and the Raman scattered light Lr generated by the interaction between the light L1 and the sample S is detected by a spectrometer 5, and spectroscopic spectrum data of the Raman scattered light Lr is obtained. By analyzing the spectroscopic spectrum data obtained by the spectrometer 5 using a computer 6, various physical properties of the sample S, such as the molecular structure, crystallinity, orientation, and distortion amount, can be evaluated. Examples of the sample S include semiconductor materials, polymers, cells, and pharmaceuticals.

[0027] Raman spectrometry device 1 Figure 1 As shown in the figure, the light source unit 2, the light guide optical system 3, the spectroscopic optical system 4, the spectroscopic device 5, the computer 6, and the display unit 7 are provided. In the following description, for convenience of description, the light incident on the spectroscopic device 5 via the spectroscopic optical system 4 is sometimes distinguished from the Raman scattered light Lr and referred to as light L1. In the spectroscopic device 5 incorporated in the Raman spectrometry device 1, the light L1 refers to the Raman scattered light Lr.

[0028] The light source unit 2 is a part that generates the light L0 that is irradiated to the sample S. As the light source constituting the light source unit 2, for example, a laser light source, a light emitting diode, etc. that is an excitation light source for Raman spectroscopy can be used. The light guide optical system 3 is a part that guides the Raman scattered light Lr generated by irradiating the sample S with the light L0 to the spectroscopic device 5. The light guide optical system 3 is composed of, for example, a collimating lens, one or more reflective mirrors, a slot, etc.

[0029] The spectroscopic optical system 4 is a part that decomposes the light L1 into wavelengths in a specified direction. The spectroscopic optical system 4 is composed of a spectroscopic element that decomposes the light L1 into wavelengths in a specific direction. As the spectroscopic element, a prism, a plane diffraction grating, a concave diffraction grating, or the like can be used. The Raman scattered light Lr is spectroscopically separated by the spectroscopic optical system 4 and input to the spectroscopic device 5.

[0030] exist Figure 1 In the embodiment, the spectroscopic optical system 4 and the spectroscopic device 5 are configured as separate bodies, but the spectroscopic optical system 4 may be incorporated as a component of the spectroscopic device 5. That is, the spectroscopic device 5 may further include a spectroscopic optical system 4 including a spectroscopic element for splitting the light L1 along the wavelength separation direction. In this case, by providing the spectroscopic device 5 with the wavelength separation function of the light L1, the convenience is improved.

[0031] The spectrometer 5 is a part that receives the light L1 decomposed by wavelength in a specified direction and outputs the spectroscopic spectrum data of the light L1. In the present embodiment, the spectrometer 5 receives the Raman scattered light Lr decomposed by the spectroscopic optical system 4 in a specific wavelength decomposition direction, and outputs the spectroscopic spectrum data of the Raman scattered light Lr to the computer 6.

[0032] The computer 6 is physically equipped with a storage device such as a RAM, a ROM, a processor such as a CPU (computational circuit), a communication interface, etc. As the computer 6, for example, a personal computer, a cloud server, an intelligent device (a smart phone, a tablet terminal, etc.) can be used. The computer 6 can be connected to the light source unit 2 and the spectrometer 5 of the Raman spectrometry device 1 for information communication, and these components can be controlled comprehensively. The computer 6 also functions as an analysis unit 8 that analyzes the physical properties of the sample S based on the spectroscopic spectrum data received from the generation unit 13. The computer 6 outputs information showing the analysis results in the analysis unit 8 to the display unit 7.

[0033] The spectroscopic device 5 is as follows Figure 1As shown in the figure, the spectroscopic device 5 includes a pixel unit 11, a conversion unit 12, a generating unit 13, and a specifying unit 14. The pixel unit 11 includes a plurality of pixels 21, and these pixels 21 receive the light L1 decomposed by wavelength and convert it into an electrical signal. In the present embodiment, the pixel unit 11 and the first conversion unit 12A (described later) are composed of an imaging sensor 10. In the present embodiment, the spectroscopic device 5 is configured as a camera including the imaging sensor 10, the second conversion unit 12B (described later), the generating unit 13, and the specifying unit 14.

[0034] Here, the spectroscopic device 5 and the computer 6 are separate bodies, but the spectroscopic device 5 may be a camera having an image sensor 10, a second conversion unit 12B, a generating unit 13, and a specific unit 14, and a computer 6 (analyzer 8) connected to the camera by electrical connection or wireless communication so that information can be communicated with each other. In this case, the spectroscopic device has an analysis function of the spectroscopic spectrum data to improve convenience. The spectroscopic device 5 may be a camera having an image sensor 10 and a second conversion unit 12B, and a generating unit 13, a specific unit 14, and a computer 6 that functions as an analyzer 8.

[0035] As the imaging sensor 10, for example, a qCMOS (quantitative complementary metal oxide semiconductor) image sensor (registered trademark) that can identify the number of photons or photoelectrons, a SPAD (single photon avalanche diode) image sensor, an MPPC (multi-pixel photon counter: registered trademark), etc. can be cited. In the present embodiment, the imaging sensor 10 is composed of a qCMOS image sensor. In the present embodiment, the number of photons refers to the number of photons incident on each pixel 21 of the imaging sensor 10, or the number of photoelectrons generated by each pixel 21 of the imaging sensor 10.

[0036] Figure 2 FIG. 1 is a diagram showing the structure of an imaging sensor. Figure 2 The qCMOS image sensor among the above sensors is exemplified in FIG. Figure 2 As shown, in the pixel unit 11 of the image sensor 10, a plurality of pixels 21 are arranged in a row direction and a column direction perpendicular to the row direction. Here, the row direction is along the wavelength separation direction of the spectroscopic optical system 4, and the column direction is along the vertical merging direction described later. Figure 2 In the example, for the sake of convenience, 3 rows×3 columns of pixels 21 are shown, but in the actual pixel unit 11, n rows×m columns of pixels 21 are arranged (see Fig. 9 wait).

[0037] Each pixel 21 has a photodiode 22 and an amplifier 23. The photodiode 22 accumulates electrons (photoelectrons) generated by the input of the light L1 as electric charge. The amplifier 23 converts the electric charge accumulated in the photodiode 22 into an electric signal (for example, a signal indicating a voltage value) and amplifies it. The electric signal amplified by the amplifier 23 is transmitted to the vertical signal line 25 connecting the pixels 21 in the row direction by switching the selection switch 24 of each pixel 21. The electric signal transmitted to the vertical signal line 25 is sent to the A / D converter 27 via the low-pass filter 26 for noise removal. In addition, in the imaging sensor 10, each pixel 21 may be configured to have a low-pass filter 26 and an A / D converter 27.

[0038] When the electric signal amplified by the amplifier 23 is read, random noise, ie, read noise, is generated in the amplifier 23 . Figure 3 is a graph showing the relationship between the number of electrons and the probability density. In this graph, the horizontal axis represents the number of electrons and the vertical axis represents the probability density. Figure 3 As shown, the number of electrons generated by the input photons follows a Poisson distribution.

[0039] exist Figure 3 The probability distribution of electrons when two photons are output on average to one pixel is shown in FIG. Figure 3 As the readout noise, 0.12[e - rms]、0.15[e - rms]、0.25[e - rms]、0.35[e - rms]、0.40[e - rms]、0.45[e - rms], 1.0[e - rms] 7 cases. Figure 3 The results shown show that the smaller the read noise, the sharper the peak of the probability distribution waveform appears, and the clearer the division of the distribution of each electron number. Therefore, the size of the read noise that can divide the electron number can be obtained by whether the peak of the probability distribution can be identified.

[0040] The conversion unit 12 is as follows Figure 1 As shown, this is a part that converts electrical signals from a plurality of pixels 21 into the number of photons. The conversion section 12 includes a first conversion section 12A that converts the electrical signals into digital values, and a second conversion section 12B that converts the digital values ​​into the number of photons based on threshold data (reference data) stored in advance.

[0041] In this embodiment, the first conversion unit 12A is composed of the above-mentioned A / D converter 27. The A / D converter 27 converts the analog value represented by the electrical signal output from the amplifier 23 of each of the plurality of pixels 21 into a digital value. The converted digital value is output to the second conversion unit 12B via the output unit 28. The digital value output from the A / D converter 27 is represented by the following formula (1). Digital value [DN] = gain [DN / e] × number of electrons [e] + offset value [DN]…(1)

[0042] Figure 4 (a) and Figure 4 (b) is a diagram showing an example of conversion from an analog value to a digital value. Figure 4 (a) shows that the readout noise is 0.15[e - rms], the probability distribution of electrons when two photons are input to one pixel on average. Figure 4 In (a), the thresholds for dividing the number of electrons are set based on the intermediate values ​​of the number of electrons, such as 0.5e, 1.5e, 2.5e, etc. (refer to Figure 4 The data for distinguishing these electron numbers from each other is the above-mentioned threshold data.

[0043] exist Figure 4 In (b), the gain is 11 [DN / e] and the offset value is 100 [DN]. As shown in the figure, when the gain is 11 [DN / e], the distribution of digital values ​​can be approximated to the distribution of analog values. In addition, by making the gain an odd number, the digital value corresponding to the threshold is suppressed. By making the gain value larger, the output digital value can be closer to the analog value. In this embodiment, the gain of the pixel unit 11 can be, for example, 10 [DN / e] or more.

[0044] return Figure 1 The second conversion unit 12B, the generating unit 13 and the specific unit 14 described later are physically composed of a computer system having a storage device such as RAM, ROM, a processor (calculation circuit) such as CPU, a communication interface, etc. The second conversion unit 12B can be composed of a PLC (programmable logic controller) or a FPGA (field-programmable gate array).

[0045] The second conversion unit 12B holds reference data for converting the digital value output from the first conversion unit 12A into the number of photons. For the reference data, a lookup table is used, for example. The reference data is generated by considering the deviation of the gain and offset values ​​between the pixels 21. The reference data is generated based on, for example, the gain and offset values ​​of each of the plurality of pixels 21. The reference data is composed of, for example, threshold data of each pixel 21.

[0046] The threshold data is data for dividing the number of electrons. Figure 5 2 is a schematic diagram showing the process of obtaining the offset value. The digital value output from the A / D converter 27 is expressed by the above-mentioned formula (1). The offset value is expressed by the digital value output when the light L1 is not input. In this embodiment, Figure 5 As shown, a plurality of digital values ​​are acquired from a plurality of dark images acquired by the pixel unit 11 in a state where the light L1 is not input. Then, the acquired digital values ​​are averaged for each pixel to acquire an offset value.

[0047] Figure 6 2 is a schematic diagram showing the process of obtaining the gain. When obtaining the gain of each pixel 21, first, a plurality of frame images obtained by the pixel unit 11 are obtained in sufficient quantity. Then, the average light signal value S[DN] and the standard deviation N[DN] of the digital values ​​in each pixel 21 are obtained. In this case, the gain is calculated by N 2 / S represents that the gain can be derived from the average optical signal value S and the standard deviation N.

[0048] For example, when the middle value of the number of electrons is set as the threshold value, the threshold value representing the lower limit of each number of electrons is expressed by the following formula (2). In addition, the threshold value representing the upper limit of each number of electrons is expressed by the following formula (3). The range represented by the lower limit threshold value and the upper limit threshold value is the range of the threshold value corresponding to the number of electrons. Threshold (lower limit) = (number of electrons - 0.5) × gain + offset value… (2) Threshold (upper limit) = (number of electrons + 0.5) × gain + offset value…(3)

[0049] Figure 7 This is a diagram schematically showing the corresponding relationship between the gain and offset value and the threshold value. In this figure, the threshold value when the number of electrons is determined to be 5 is displayed for each pixel. For example, when the gain is 10.9 [DN / e] and the offset value is 97.7 [DN], the lower threshold value is 146.8 [DN] and the upper threshold value is 157.7 [DN].

[0050] Figure 8: is a diagram schematically showing the process of converting the digital value of each pixel into the number of electrons. As shown in the figure, the second conversion unit 12B can derive the number of electrons corresponding to the digital value by referring to the threshold data. For example, the number of electrons of the pixel 21 whose digital value is 162 [DN] is derived as 5 electrons. The second conversion unit 12B can obtain the average number of photons by dividing the average number of electrons by the quantum efficiency for each pixel. When the quantum efficiency is 100%, the number of electrons and the number of photons are the same number. The second conversion unit 12B outputs the number of photons derived for each pixel 21 to the generating unit 13. In addition, when the second conversion unit 12B outputs the number of photons to the generating unit 13, it outputs instruction information to the specific unit 14 to indicate the start of processing.

[0051] Again, return Figure 1 The generating unit 13 is a part that integrates the number of photons of multiple pixels 21 belonging to the same column and generates spectral spectrum data based on the integration result. The integration of the number of photons of multiple pixels 21 belonging to the same column is equivalent to the so-called vertical merging process. Here, the number of photons converted from the electrical signal is vertically merged instead of the electrical signal from each pixel 21. The spectral spectrum data can be a two-dimensional image representing the number of photons in each pixel 21, or a histogram plotting the number of pixels for the number of photons. The generating unit 13 outputs the generated spectral spectrum data to the computer 6.

[0052] The specifying unit 14 is a part that specifies the pixel 21 used for the integration of the number of photons among the multiple pixels 21 belonging to the same column. That is, the specifying unit 14 is a part that specifies the pixel 21 used for vertical binning in the generating unit 13. The specifying unit 14 specifies, for example, a pixel 21 whose readout noise is below a threshold as the pixel 21 used for the integration of the number of photons. When receiving the instruction information from the second conversion unit 12B, the specifying unit 14 generates specific information indicating the specified pixel 21 and outputs it to the generating unit 13. In the generating unit 13, the number of photons of the multiple pixels 21 belonging to the same column is integrated using only the pixel 21 indicated by the specific information, and the spectroscopic spectrum data based on the integration result is generated.

[0053] The specific part 14 is, for example, Fig. 9 As shown in FIG. 1 , a readout noise map M1 for the pixel unit 11 can be stored. The readout noise map M1 is prepared by measuring the readout noise of each pixel 21 before the pixel unit 11 is incorporated into the spectroscopic device 5, for example. Fig. 9 In the example of FIG. 1 , a readout noise map is shown for a horizontally long pixel portion 11 in which the number of pixels in the row direction is greater than the number of pixels in the column direction. In the readout noise map M1, the threshold value of the readout noise is set to 0.3 [e - The specifying unit 14 specifies the read noise as 0.3[e -rms] or less as pixels for photon number integration. The identifying unit 14 selects pixels 21 with readout noise exceeding 0.3 [e - rms] pixels 21( Fig. 9 The pixel 21Fa in is excluded from the pixels used for the integration of the number of photons.

[0054] The threshold value in the read noise map M11 is set based on the relationship between the read noise and the misconversion rate when converting an electrical signal into the number of photons. Fig.10 is a graph showing the relationship between the readout noise and the error conversion rate when converting the electrical signal into the number of photons. As shown in the graph, when the threshold of the readout noise is set to 0.3 [e - rms], the error conversion rate when converting electrical signals into photons can be suppressed to less than 10%.

[0055] The specific unit 14 can specify the pixels 21 used for the integration of the number of photons in such a manner that the number of pixels 21 used for the integration of the number of photons is the same in each column. In this case, the specific unit 14 can specify the number of integrated pixels of other columns in correspondence with the number of integrated pixels of the column with the most pixels excluded from the pixels used for the integration of the number of photons. For example, when the number of pixels in each column is 1024 pixels and the number of integrated pixels of the column with the most pixels excluded from the pixels used for the integration of the number of photons is 1020 pixels (excluding 4 pixels), any 4 pixels of other columns can be set as dummy pixels not used for the integration of the number of photons, and the number of integrated pixels of all columns can be made consistent with 1020 pixels.

[0056] The specific unit 14 may store in advance the region information indicating the region where no light L1 is input in the pixel unit 11, and exclude the pixel 21 corresponding to the region information from the accumulation of the number of photons. The region information is generated in advance based on the specification or arrangement of the spectroscopic element in the spectroscopic optical system 4, for example. The region information may be superimposed on the readout noise map M1. Fig. 9 In the example of FIG. 1 , the pixels 21 located at both ends of each column belong to the region R where no light L1 is input. The pixels 21 ( Fig. 9 Pixel 21Fb) is excluded from the integration of the number of photons in each column.

[0057] As described above, the spectroscopic optical system 4 includes a spectroscopic element that splits the light L1 in the wavelength separation direction. However, in reality, the spectroscopic spectrum imaged on the pixel unit 11 via the spectroscopic optical system 4 is not linear due to the influence of the aberration of the optical system, as represented by, for example, Czerny-Turner type spectrometry.

[0058] In e.g. Fig.11In (a), for the pixel unit 11, five wavelength-decomposed spectral images (31A to 31E from the short wavelength side) are formed in a state where they are separated from each other in the row direction (wavelength decomposition direction). Fig.11 In example (a), the spectral spectrum image 31C located in the center of the pixel portion 11 forms a straight line in the column direction (vertical merging direction), but the spectral spectrum images 31A, 31B and the spectral spectrum images 31D, 31E all produce a so-called pincushion-shaped distortion in which the image is bent toward the center side of the pixel portion 11.

[0059] The amount of distortion of the spectral images increases as the image moves away from the center of the pixel unit 11. The spectral images 31A and 31E have a larger amount of distortion than the spectral images 31B and 31D. If the number of photons in the pixels 21 of each column is vertically combined in a state where such distortion occurs, the image is as follows: Fig.11 As shown in (b), among the spectral data 32A to 32E based on the spectral images 31A to 31E, there is a risk that the wavelength resolution in the row direction is reduced according to the degree of distortion in the spectral data 32A, 32B, 32D, and 32E based on the spectral images 31A, 31B, 31D, and 31E except the spectral image 31C. In addition, there is a problem that the SN ratio is reduced due to the reduction of the peak value of the spectral data 32A, 32B, 32D, and 32E.

[0060] In order to solve this problem, the specifying unit 14 may specify the pixel 21 for integrating the number of photons and the integration ratio in the pixel 21 based on the aberration information of the light L1 in the spectroscopic optical system 4, and the generating unit 13 may integrate the number of photons in the plurality of pixels 21 using the integration ratio. Specifically, the specifying unit 14 may be as follows: Fig.12 As shown in FIG. 1 , the integrated ratio map M2 for the pixel portion 11 is provided. The aberration information for generating the integrated ratio map M2 can be obtained in advance by using simulation data or measured data when the light L1 is guided to the spectroscopic optical system 4. When the measured data is used, the aberration information can be obtained based on the spectroscopic spectrum data of a plurality of light images without local distortion.

[0061] The specifying unit 14 can refer to the integration ratio map M2 and perform sub-pixel processing based on the integration ratio of a plurality of pixels 21 adjacent in the row direction when vertically combining the number of photons. Fig.12 The integrated ratio of a portion of the pixel 21 corresponding to the spectral spectrum image 31B and the spectral spectrum image 31E in the integrated ratio diagram M of the entire pixel unit 11 is extracted and displayed. As described above, the distortion of the spectral spectrum image 31E is greater than that of the spectral spectrum image 31B. Fig.12In the example of FIG. 3 , in the vertical merging of the pixel 21 corresponding to the spectral spectrum image 31B, sub-pixel processing based on the integration ratio of two pixels 21 adjacent in the row direction is implemented. In the vertical merging of the pixel 21 corresponding to the spectral spectrum image 31E, sub-pixel processing based on the integration ratio of three pixels 21 adjacent in the row direction is implemented.

[0062] exist Fig.12 In the example, the number of photons of the pixel 21 with coordinates (x, y) is set to P(x, y). If it is assumed that the reference x coordinate of the pixel 21 corresponding to the spectral image 31B is 300 and the y coordinate is -512 to +512, the vertical combination of the pixel 21 corresponding to the spectral image 31B is expressed by the following formula (4). If it is assumed that the reference x coordinate of the pixel 21 corresponding to the spectral image 31E is 700 and the y coordinate is -512 to +512, the vertical combination of the pixel 21 corresponding to the spectral image 31E is expressed by the following formula (5). [Number 1] [Number 2]

[0063] exist Fig.12 In FIG. 3 , as a part of the pixel 21 corresponding to the spectral spectrum image 31B, four pixels of coordinates (300, -500), coordinates (301, -500), coordinates (300, -501), and coordinates (301, -501) are displayed. For these four pixels, the integration ratio of P(300, -500) is 80%, the integration ratio of P(301, -500) is 20%, the integration ratio of P(300, -501) is 90%, and the integration ratio of P(301, -501) is 10%. Therefore, in equation (4), α(300, -500) is obtained by the following equation (6), and α(300, -501) is obtained by the following equation (7). α(300,-500)=(80×P(300,-500)+20×P(301,-500)) / 100…(6) α(300,-501)=(90×P(300,-501)+10×P(301,-501)) / 100…(7)

[0064] In addition, Fig.12In the figure, as part of pixel 21 corresponding to the spectral spectrum image 31E, 9 pixels of coordinates (699,350), coordinates (700,350), coordinates (701,350), coordinates (699,349), coordinates (700,349), coordinates (701,349), coordinates (699,348), coordinates (700,348), and coordinates (701,348) are displayed. For these 9 pixels, the integration ratio of P(699,350) is 15%, the integration ratio of P(700,350) is 70%, the integration ratio of P(701,350) is 15%, the integration ratio of P(699,349) is 20%, the integration ratio of P(700,349) is 70%, the integration ratio of P(701,349) is 10%, the integration ratio of P(699,348) is 25%, the integration ratio of P(700,348) is 70%, and the integration ratio of P(701,348) is 5%.

[0065] Therefore, in equation (5), β(700, 350) is obtained by equation (8) below, β(700, 349) is obtained by equation (9) below, and β(700, 348) is obtained by equation (10) below. β(700,350)=(15×P(699,350)+70×P(700,350)+15×P(701,350))…(8) β(700,349)=(20×P(699,349)+70×P(700,349)+10×P(701,349))…(9) β(700,348)=(25×P(699,348)+70×P(700,348)+5×P(701,348))…(10)

[0066] Fig.13 Schematic diagram showing spectral spectrum data obtained by vertical merging using an integration ratio diagram. As shown in the figure, by integrating the number of photons of a plurality of pixels 21 using an integration ratio based on aberration information of light L1, even when distortion occurs in spectral spectrum images 31A to 31E, it is possible to suppress reduction in wavelength resolution in the row direction in each of spectral spectrum data 32A to 32E based on spectral spectrum images 31A to 31E. In addition, reduction in peak value is suppressed, and improvement in SN ratio is also sought.

[0067] In addition, Fig.12 In the example of FIG. 1 , only the integrated ratio map M2 of the pixel portion 11 is displayed, but the integrated ratio map M2 may be overlapped with the integrated ratio map M2. Fig. 9 The readout noise graph M1 shown. In addition, the integrated ratio graph M2 can be further overlapped Fig. 9In this case, the generation unit 13 excludes the pixel 21 specified by reading the noise map M1 and the region information from the pixels used for the integration of the number of photons, and performs vertical binning by sub-pixel processing using the integration ratio map M2.

[0068] Fig.14 1 is a flow chart showing a spectroscopic method according to an embodiment of the present disclosure. The spectroscopic method is a method for receiving light decomposed by wavelength along a predetermined direction and obtaining spectroscopic spectrum data of the light. The spectroscopic method of this embodiment is implemented using the spectroscopic device 5 described above. Fig.14 As shown, the spectroscopic method includes: a light receiving step (step S01), a conversion step (step S02), a generation step (step S03), and an analysis step (step S4).

[0069] In the light receiving step S01, the wavelength-decomposed light L1 or Raman scattered light Lr is received and converted into an electrical signal by a plurality of pixels 21 arranged in a row direction along the wavelength decomposition direction and in a column direction perpendicular to the row direction. In the conversion step S02, the electrical signals from the plurality of pixels 21 are converted into the number of photons. In this embodiment, the electrical signal is converted into a digital value by the first conversion unit 12A, and then the digital value is converted into the number of photons by the threshold data retained by the second conversion unit 12B.

[0070] In the generation step S03, the photon counts of the plurality of pixels 21 belonging to the same column are integrated, and spectroscopic spectrum data based on the integrated result is generated. In this embodiment, pixels 21 whose readout noise is below a threshold value when the photon count is integrated are specified as pixels 21 for the photon count integration, and only pixels 21 whose readout noise is below a threshold value are specified as pixels 21 for the photon count integration.

[0071] In the analysis step S04, the sample S is analyzed based on the spectral spectrum data generated in the generation step S03. For example, the waveform, peak position, peak intensity, half-width, etc. of the spectral spectrum are analyzed to evaluate various physical properties of the sample S, such as molecular structure, crystallinity, orientation, and distortion amount.

[0072] As described above, in the spectroscopic device 5, based on the light received by each pixel 21 constituting the pixel unit 11, the electrical signal output from each pixel 21 is converted into the number of photons. When converting from the electrical signal to the number of photons, for example, the number of photons of the pixel 21 that has not received light is zero. Therefore, when the number of photons of a plurality of pixels 21 belonging to the same column is integrated after conversion to the number of photons, the influence of the readout noise of each pixel 21 can be sufficiently reduced. Therefore, in the spectroscopic device 5, the spectroscopic spectrum data can be obtained with an excellent SN ratio.

[0073] The spectroscopic device 5 is provided with a specifying unit 14 that specifies the pixel 21 used for the integration of the number of photons among the plurality of pixels 21 belonging to the same column. By specifying the pixel 21 suitable for the integration of the number of photons using the specifying unit 14, the influence of the read noise of each pixel 21 can be further reduced. By reducing the influence of the read noise of each pixel 21, the conversion accuracy from the electrical signal to the number of photons is improved, and the SN ratio of the spectroscopic spectrum data is further improved.

[0074] In the spectroscopic device 5, the specifying unit 14 specifies the pixel 21 whose read noise is below the threshold value as the pixel 21 used for the integration of the number of photons. As a result, the influence of the read noise of each pixel 21 can be further reduced. By reducing the influence of the read noise of each pixel 21, the conversion accuracy from the electrical signal to the number of photons is improved, and the SN ratio of the spectroscopic spectrum data is further improved.

[0075] In the spectrometer 5, the threshold of the read noise is set to 0.3 [e - rms]. As a result, the error conversion rate when converting the electrical signal into the number of photons can be suppressed to 10% or less.

[0076] In the spectroscopic device 5, the specifying unit 14 specifies the pixels used for the integration of the number of photons so that the number of pixels 21 used for the integration of the number of photons is the same in each column. Thus, the integrated value of the read noise of the pixels 21 in each column used for the integration of the number of photons can be made uniform in the row direction. Therefore, the SN ratio of the spectroscopic spectrum data can be stably improved.

[0077] In the spectroscopic device 5, the specifying unit 14 specifies the pixel 21 for integrating the number of photons and the integration ratio in the pixel 21 based on the aberration information of the light in the spectroscopic optical system 4, and the generating unit 13 uses the integration ratio to integrate the number of photons of the plurality of pixels 21. According to this configuration, even when distortion due to aberration occurs in the image of the wavelength-decomposed light L1, the integration of the number of photons of the plurality of pixels 21 can be appropriately performed.

[0078] In the spectroscopic device 5, the specifying unit 14 holds in advance the region information indicating the region where no light is input in the pixel unit 11, and excludes the pixels 21 belonging to the region R indicated by the region information from the integration of the number of photons. Thus, since the integration of the number of photons can exclude unnecessary pixels, the influence of the read noise of each pixel 21 can be further reduced.

[0079] In the spectroscopic device 5, the conversion unit 12 is composed of the first conversion unit 12A and the second conversion unit 12B, and the first conversion unit 12A converts the electrical signal into a digital value, and the second conversion unit 12B converts the digital value into the number of photons based on the reference data held in advance. Thus, the number of photons of each pixel 21 can be obtained while suppressing the influence of the deviation of the gain and offset of each pixel 21.

[0080] In the Raman spectrometry device 1 configured by incorporating the above-mentioned spectrometer 5, the electric signal output from each pixel 21 is converted into the number of photons based on the Raman scattered light Lr received by each pixel 21 constituting the pixel unit 11. When converting from the electric signal to the number of photons, for example, the number of photons of the pixel 21 that has not received the Raman scattered light Lr is zero. Therefore, when the number of photons of a plurality of pixels 21 belonging to the same column is integrated after conversion into the number of photons, the influence of the read noise of each pixel 21 can be sufficiently reduced. Therefore, in the Raman spectrometry device 1, the spectroscopic spectrum data of the Raman scattered light Lr can be obtained with an excellent SN ratio.

[0081] In addition, the spectrometer 5 is not limited to the application to the Raman spectrometer 1, and can be applied to other spectrometers such as fluorescence spectrometers, plasma spectrometers, and luminescence spectrometers. In addition, the spectrometer 5 can be applied to other spectrometers such as film thickness measurement devices, optical density measurement, LIBS (Laser-Induced Breakdown Spectroscopy) measurement, and DOAS (Differential Optical Absorption Spectroscopy) measurement. Explanation of symbols

[0082] 1…Raman spectrometer; 2…light source; 3…light-guiding optical system; 4…spectrometric optical system; 5…spectrometric device; 8…analyzer; 11…pixel; 12…converter; 12A…first converter; 12B…second converter; 13…generator; 14…specification; 21…pixel; L1…light; Lr…Raman scattered light.

Claims

1. A spectroscopic device, wherein: A spectroscopic device that receives light decomposed by wavelength in a predetermined direction by a spectroscopic optical system including a spectroscopic element and outputs spectroscopic spectrum data of the light. It has: a pixel unit, a conversion unit, and a generation unit, The pixel unit includes a plurality of pixels that receive the wavelength-decomposed light and convert it into an electrical signal, and The plurality of pixels are arranged in a row direction along a wavelength separation direction and in a column direction perpendicular to the row direction. The conversion unit converts the electrical signals from the plurality of pixels into photon numbers. The generating unit integrates the number of photons of a plurality of pixels belonging to the same column and generates spectroscopic spectrum data based on the integration result.

2. The spectroscopic device according to claim 1, wherein: The present invention further comprises a specifying unit that specifies a pixel used for the integration of the number of photons among the plurality of pixels belonging to the same column.

3. The spectroscopic device according to claim 2, wherein: The specifying unit specifies pixels having a readout noise that is equal to or less than a threshold value as pixels to be used for the integration of the number of photons.

4. The spectroscopic device according to claim 3, wherein: The threshold of the read noise is set to 0.3[e - rms].

5. The spectroscopic device according to any one of claims 2 to 4, wherein: The specifying unit specifies pixels used for the integration of the number of photons so that the number of pixels used for the integration of the number of photons becomes the same in each column.

6. The spectroscopic device according to any one of claims 2 to 4, wherein: The specifying unit specifies a pixel used for the integration of the number of photons and an integration ratio of the pixel based on the aberration information of the light in the spectroscopic optical system. The generating unit integrates the number of photons of the plurality of pixels using the integration ratio.

7. The spectroscopic device according to any one of claims 2 to 4, wherein: The specifying unit holds in advance region information indicating a region in the pixel unit to which the light is not input, and excludes pixels corresponding to the region information from the integration of the number of photons.

8. The spectroscopic device according to any one of claims 1 to 4, wherein: The conversion section includes: a first conversion section that converts the electrical signal into a digital value; and a second conversion section that converts the digital value into the number of photons based on reference data held in advance.

9. The spectroscopic device according to any one of claims 1 to 4, wherein: The device further comprises: an analyzing unit configured to analyze the spectroscopic spectrum data.

10. The spectroscopic device according to any one of claims 1 to 4, wherein: The invention further comprises a spectroscopic optical system including a spectroscopic element for splitting the light in the wavelength separation direction.

11. A Raman spectrometry device, wherein: have: The spectroscopic device according to any one of claims 1 to 4; a light source unit that generates light to irradiate the sample; and The light guide optical system guides the Raman scattered light generated by irradiating the sample with the light to the spectroscopic device.

12. A spectroscopic method, wherein: It is a spectroscopic method that receives light decomposed by wavelength along a specified direction and obtains the spectroscopic spectrum data of the light. have: A light receiving step, wherein a plurality of pixels arranged in a row direction along a wavelength decomposition direction and in a column direction perpendicular to the row direction receive the wavelength-decomposed light and convert the light into an electrical signal; a conversion step of converting the electrical signals from the plurality of pixels into photon numbers; and The generating step integrates the photon numbers of a plurality of pixels belonging to the same column and generates spectroscopic spectrum data based on the integration result.

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