Spectroscopic measurement device and spectroscopic measurement method

Abstract

A spectroscopic measurement device 1 comprises an optical system 10, a photodetector 20, and a control unit 30, and acquires a spectrum of measurement light composed of repeating light pulses. A light receiving unit 21 of the photodetector 20 has a light receiving surface in which a plurality of pixels 22 are two-dimensionally arranged in (M1 + M2) rows and N columns. The light receiving surface is divided into a first region 21A of M1 rows and N columns, and a second region 21B of M2 rows and N columns. The control unit 30 controls operations including charge accumulation of each pixel in the first region 21A, transfer of the charge accumulated by each pixel of the first region 21A to a first output unit 23A, and output of a first electrical signal from the first output unit 23A in synchronization with light pulse generation timing. The control unit 30 controls operations in the same manner with respect to the second region 21B and a second output unit 23B. As a result, it is possible to achieve a spectroscopic measurement device capable of efficiently acquiring, with a simple configuration, a spectrum of measurement light composed of rapidly repeating light pulses under various exposure conditions.

Description

Spectroscopic measurement device and spectroscopic measurement method

[0001] The present disclosure relates to a spectroscopic measurement device and a spectroscopic measurement method.

[0002] Spectroscopic measurement technology can obtain the spectrum of the measured light by receiving the spectral image of the measured light generated in the object using a photodetector, and can analyze the composition of the object or monitor phenomena in the object based on the spectrum. For example, by irradiating the object with excitation light and obtaining the spectrum of the fluorescence generated in the object, the object can be analyzed based on the fluorescence spectrum.

[0003] The photodetector used here is, for example, a CCD image sensor or a CMOS image sensor. The photodetector has a light-receiving surface on which a plurality of pixels are arranged two-dimensionally. A spectral image is formed on the light-receiving surface so that its wavelength axis is parallel to the row direction of the light-receiving surface. Each pixel on the light-receiving surface generates and accumulates electric charges in response to incident light. The electric charges accumulated by each pixel are integrated for each column, and an electrical signal corresponding to the integrated amount of electric charge for each column is output as spectral data.

[0004] In such spectroscopic measurement techniques, if it is possible to repeatedly irradiate an object with excitation light pulses to repeatedly generate fluorescent pulses in the object and obtain the spectra of the fluorescent pulses under various conditions (e.g., conditions such as the start and end times of charge accumulation relative to the light pulse waveform), it is expected that the object can be analyzed in more detail based on these spectra.

[0005] The photodetector described in Patent Document 1 has a light-receiving surface on which a spectral image of the light to be measured is formed, which is divided into a first region and a second region, and it is possible to acquire a spectrum from each of the first region and the second region. It is expected that the use of such a photodetector will enable acquisition of two types of spectra from the same light to be measured.

[0006] JP 2018-174324 A

[0007] In the case of the light to be measured that consists of repeatedly occurring light pulses, as in the example of fluorescence described above, if the period of the repeated occurrence of the light pulses is short, it is difficult to efficiently acquire the spectrum of the light to be measured under various exposure conditions. Generally, a photodetector used for spectroscopic measurement has a large number of columns of pixel arrays, and it takes a long time to output an electrical signal corresponding to the amount of charge accumulated for each column.

[0008] During the period when this electrical signal is being output, even if the pixel that received the light pulse generates an electric charge, the electric charge must be discharged without being stored. To address this problem, it is conceivable to use a photodetector designed to operate at a high speed clock, but realizing such a photodetector is difficult in terms of device design and noise design.

[0009] The embodiments aim to provide a spectroscopic measurement device and a spectroscopic measurement method that can efficiently acquire the spectrum of light to be measured, which is made up of light pulses that are repeatedly generated at high speed, under various exposure conditions with a simple configuration.

[0010] An embodiment is a spectroscopic measurement device. The spectroscopic measurement device includes: (1) an optical system that forms a spectral image by dispersing light to be measured, which is composed of repetitive optical pulses; (2) a photodetector that detects the spectral image; and (3) a control unit that controls the operation of the photodetector. (4) The photodetector includes: (a) a light-receiving unit in which a plurality of pixels, each generating an electric charge in response to incident light, are two-dimensionally arranged in (M1+M2) rows and N columns (M1, M2, and N are each an integer of 2 or greater) on a light-receiving surface, the light-receiving surface being divided into a first region of M1 rows and N columns and a second region of M2 rows and N columns, and the spectral image is formed on the light-receiving surface so that the wavelength axis of the spectral image is parallel to the row direction of the light-receiving surface; (b) a first output unit that integrates, for each column, the electric charges generated and accumulated by each pixel in the first region during a first charge accumulation period and outputs a first electrical signal corresponding to the integrated amount of electric charge for each column; and (c) a second output unit that integrates, for each column, the electric charges generated and accumulated by each pixel in the second region during a second charge accumulation period. and a second output unit that accumulates charge for each column and outputs a second electrical signal corresponding to the accumulated charge amount for each column, (5) the control unit, where either K1 or K2 is an integer of 1 or greater and the other is an integer of 2 or greater, (a) synchronizes with the generation timing of each optical pulse of the light to be measured, to cause charge accumulation in each pixel of the first region over a first charge accumulation period and transfer of the charge accumulated by each pixel of the first region to the first output unit K1 times, and then outputs a first electrical signal corresponding to the accumulated charge amount for each column K1 times from the first output unit, and (b) synchronizes with the generation timing of each optical pulse of the light to be measured, to cause charge accumulation in each pixel of the second region over a second charge accumulation period and transfer of the charge accumulated by each pixel of the second region to the second output unit K2 times, and then outputs a second electrical signal corresponding to the accumulated charge amount for each column K2 times from the second output unit.

[0011] An embodiment is a spectroscopic measurement method, which uses a photodetector having a light receiving portion in which a plurality of pixels, each generating an electric charge in response to incident light, are two-dimensionally arranged in (M1+M2) rows and N columns (M1, M2, and N are each an integer of 2 or greater) on a light receiving surface, and the light receiving surface is divided into a first region of M1 rows and N columns and a second region of M2 rows and N columns, the spectroscopic measurement method comprising: (1) a spectroscopic step of spectroscopically measuring light to be measured, which is made up of repeatedly occurring optical pulses, to form a spectral image; and (2) a detection step of detecting the spectral image with the photodetector, in which (3) in the spectroscopic step, the spectral image is formed on the light receiving surface so that the wavelength axis of the spectral image is parallel to the row direction of the light receiving surface, and (4) in the detection step, In this step, one of K1 and K2 is an integer of 1 or greater and the other is an integer of 2 or greater, and (a) in synchronization with the generation timing of each optical pulse of the measured light, charge accumulation in each pixel of the first region over a first charge accumulation period and transfer of the charge accumulated by each pixel of the first region are performed K1 times, and then a first electrical signal corresponding to the amount of charge accumulated for each column K1 times is output, and (b) in synchronization with the generation timing of each optical pulse of the measured light, charge accumulation in each pixel of the second region over a second charge accumulation period and transfer of the charge accumulated by each pixel of the second region are performed K2 times, and then a second electrical signal corresponding to the amount of charge accumulated for each column K2 times is output.

[0012] According to the spectroscopic measurement device and spectroscopic measurement method of the embodiment, the spectrum of the light to be measured, which is made up of light pulses that are repeatedly generated at high speed, can be efficiently acquired under various exposure conditions with a simple configuration.

[0013] FIG. 1 is a diagram showing the configuration of the spectroscopic measurement device 1. FIG. 2 is a diagram showing the configuration of the photodetector 20. FIG. 3 is a diagram showing the configuration of the light receiving unit 21 of the photodetector 20. FIG. 4 is a timing chart illustrating an example of setting a charge accumulation period using an electronic shutter function. FIG. 5 is a timing chart illustrating an example of control of the operation of the photodetector 20 by the control unit 30. FIGS. 6(a) and 6(b) are timing charts illustrating another example of control of the operation of the photodetector 20 by the control unit 30. FIG. 7 is a timing chart illustrating another example of setting a charge accumulation period using an electronic shutter function.

[0014] Hereinafter, embodiments of a spectroscopic measurement device and a spectroscopic measurement method will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are designated by the same reference numerals, and duplicate explanations will be omitted. The present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0015] 1 is a diagram showing the configuration of a spectroscopic measurement device 1. The spectroscopic measurement device 1 includes an optical system 10, a photodetector 20, and a control unit 30, and acquires the spectrum of light to be measured arriving from an object S. The light to be measured is composed of repeatedly occurring light pulses. For example, the light to be measured is composed of fluorescent pulses that are repeatedly generated in the object S by repeatedly irradiating the object S with excitation light pulses.

[0016] The optical system 10 guides the light to be measured from the object S to the light-receiving surface of the photodetector 20 and forms a spectral image of the light to be measured on the light-receiving surface of the photodetector 20. The optical system 10 may include an optical fiber for guiding light. The optical system 10 disperses the light to be measured into individual wavelength components using a spectroscopic element such as a grating or a prism, and forms the spectral image on the light-receiving surface of the photodetector 20. The optical system 10 may include optical elements such as lenses and mirrors. The optical system 10 may also be, for example, a Czerny-Turner spectrometer or a Dyson spectrometer.

[0017] The photodetector 20 has a light-receiving surface on which a plurality of pixels, each of which generates an electric charge in response to incident light, are arranged two-dimensionally. A spectral image is formed on the light-receiving surface so that the wavelength axis of the spectral image is parallel to the row direction of the light-receiving surface. The photodetector 20 is, for example, a CCD image sensor or a CMOS image sensor formed on a semiconductor substrate.

[0018] The photodetector 20 is preferably thinned by grinding the back surface of the semiconductor substrate (the surface opposite to the image sensor formation surface) and is capable of highly sensitive light detection in a wide wavelength band. A CCD image sensor is also preferred because it has higher sensitivity than a CMOS image sensor. The CCD image sensor may be an interline CCD type, a frame transfer CCD type, or a full frame transfer CCD type.

[0019] The control unit 30 controls the generation of light pulses in the object S, and controls the operation of the photodetector 20 in synchronization with the timing of the light pulse generation. For example, the control unit 30 repeatedly irradiates the object S with excitation light pulses in synchronization with a trigger signal, thereby repeatedly generating fluorescent pulses, and controls the operation of the photodetector 20 in synchronization with the same trigger signal.

[0020] The control unit 30 controls the operation of the photodetector 20 based on a trigger signal output from the external control unit 40. The external control unit 40 controls the generation of light pulses in the object S and outputs a trigger signal to the control unit 30 in synchronization with the timing of the light pulse generation. For example, the external control unit 40 repeatedly irradiates the object S with excitation light pulses in synchronization with the trigger signal, thereby repeatedly generating fluorescent pulses, and also provides the same trigger signal to the control unit 30.

[0021] Fig. 2 is a diagram showing the configuration of the photodetector 20. The photodetector 20 includes a light receiving section 21, a first output section 23A, and a second output section 23B. Fig. 3 is a diagram showing the configuration of the light receiving section 21 of the photodetector 20.

[0022] The light receiving unit 21 has a light receiving surface in which a plurality of pixels 22, each generating an electric charge in response to incident light, are two-dimensionally arranged in (M1+M2) rows and N columns. The light receiving surface is divided into a first region 21A with M1 rows and N columns and a second region 21B with M2 rows and N columns. M1, M2, and N are each an integer of 2 or greater. The wavelength axis (wavelength resolution direction) of the spectral image P formed on the light receiving surface is parallel to the row direction of the light receiving surface.

[0023] In the first region 21A, each pixel accumulates electric charges generated in response to incident light over a first charge accumulation period and transfers the accumulated electric charges column by column in the column direction (charge transfer direction A1) to the first output section 23A. The first output section 23A integrates, for each column, the electric charges generated and accumulated by each pixel in the first region 21A during the first charge accumulation period and outputs, as first spectral data, a first electrical signal corresponding to the amount of accumulated electric charges for each column.

[0024] In the second region 21B, the charges generated by each pixel in response to incident light are accumulated over a second charge accumulation period, and the accumulated charges are transferred sequentially column by column along the column direction (charge transfer direction A2) to the second output section 23B. The second output section 23B integrates the charges generated and accumulated by each pixel in the second region 21B during the second charge accumulation period for each column, and outputs a second electrical signal corresponding to the amount of accumulated charge for each column as second spectral data.

[0025] Each of the first output section 23A and the second output section 23B may include a shift register that sequentially shifts and outputs the charges integrated for each column, and an amplifier that inputs the charges sequentially output from the shift register and outputs a voltage value corresponding to the amount of charge. Alternatively, each of the first output section 23A and the second output section 23B may include an amplifier that converts the charges integrated for each column into a voltage value for each column, and a shift register that sequentially shifts and outputs the voltage value output from the amplifier for each column.

[0026] The control unit 30 controls the operation of the photodetector 20 based on a trigger signal synchronized with the timing of generation of an optical pulse of the light under measurement. The control unit 30 controls the operations of charge accumulation in each pixel in the first region 21A, transfer of the charge accumulated in each pixel in the first region 21A to the first output unit 23A (hereinafter referred to as "first vertical transfer"), and output of a first electrical signal from the first output unit 23A (hereinafter referred to as "first horizontal transfer").

[0027] The control unit 30 also controls the operations of charge accumulation in each pixel in the second region 21B, the transfer of the charges accumulated in each pixel in the second region 21B to the second output unit 23B (hereinafter referred to as "second vertical transfer"), and the output of a second electrical signal from the second output unit 23B (hereinafter referred to as "second horizontal transfer"). The control unit 30 controls the charge accumulation, first vertical transfer, and first horizontal transfer in the first region 21A and the charge accumulation, second vertical transfer, and second horizontal transfer in the second region 21B to be performed independently of each other.

[0028] More specifically, the control unit 30 performs charge accumulation and first vertical transfer K1 times for each pixel in the first region 21A over a first charge accumulation period based on a trigger signal synchronized with the generation timing of each optical pulse of the measured light, and then performs first horizontal transfer. The control unit 30 also performs charge accumulation and second vertical transfer K2 times for each pixel in the second region 21B over a second charge accumulation period in synchronization with the generation timing of each optical pulse of the measured light, and then performs second horizontal transfer. One of K1 and K2 is an integer greater than or equal to 1, and the other is an integer greater than or equal to 2.

[0029] The spectroscopic measurement method of this embodiment includes a spectroscopic step of forming a spectral image by dispersing the light to be measured, which is made up of repeatedly generated optical pulses, using the optical system 10, and a detection step of detecting the spectral image using the photodetector 20. In the detection step, the photodetector 20 is caused to perform an operation based on the control by the control unit 30.

[0030] The photodetector 20 preferably has an electronic shutter function that selects between accumulating and discharging the charge generated by each pixel. In this case, the control unit 30 can set the first charge accumulation period and the second charge accumulation period by utilizing the electronic shutter function of the photodetector 20. Note that the first charge accumulation period and the second charge accumulation period may be the same length or different lengths.

[0031] 4 is a timing chart illustrating an example of setting a charge accumulation period using the electronic shutter function, which shows, from top to bottom, a trigger signal waveform, a fluorescent light pulse waveform, accumulation / discharge of pixel charges in the first region 21A, electronic shutter operation of the first region 21A, accumulation / discharge of pixel charges in the second region 21B, and electronic shutter operation of the second region 21B.

[0032] In the example shown in this figure, an excitation light pulse is irradiated onto the object S at the rising edge of the trigger signal, and a fluorescent light pulse is generated from this point onward. The fluorescent light intensity gradually increases from the rising edge of the trigger signal, reaches a peak, and then gradually decreases.

[0033] In the first region 21A, the electronic shutter is open during the period including the peak of the fluorescent pulse (first charge accumulation period), and charges generated by the pixels are accumulated. In the second region 21B, the electronic shutter is open during the period including the tail of the fluorescent pulse after the peak (second charge accumulation period), and charges generated by the pixels are accumulated.

[0034] The first charge accumulation period and the second charge accumulation period each start at a time delayed by a certain time from the rising edge of the trigger signal, and end at a time delayed by a certain time from the first charge accumulation period. During the period in which the electronic shutter is closed, even if a charge is generated in the pixel, the charge is discharged without being accumulated.

[0035] In this way, the first charge accumulation period and the second charge accumulation period may have different start times and end times. The first charge accumulation period and the second charge accumulation period may partially overlap each other, or may not overlap. Furthermore, the first charge accumulation period may be a period that includes the peak of the fluorescent light pulse, and the second charge accumulation period may be a period that does not include the peak of the fluorescent light pulse.

[0036] 5 is a timing chart illustrating an example of control of the operation of the photodetector 20 by the control unit 30. This diagram shows, from top to bottom, a trigger signal waveform, a fluorescent light pulse waveform, electronic shutter operation of the first region 21A (accumulation / discharge of pixel charges), transfer of charges accumulated by each pixel in the first region 21A to the first output unit 23A (first vertical transfer), output of a first electrical signal from the first output unit 23A (first horizontal transfer), electronic shutter operation of the second region 21B (accumulation / discharge of pixel charges), transfer of charges accumulated by each pixel in the second region 21B to the second output unit 23B (second vertical transfer), and output of a second electrical signal from the second output unit 23B (second horizontal transfer).

[0037] In the example shown in this figure, the excitation light pulse is irradiated onto the object S at the rising edge of the trigger signal, and a fluorescent light pulse is generated from this point onward. The fluorescent light intensity gradually increases from the rising edge of the trigger signal, reaches a peak, and then gradually decreases.

[0038] In the first region 21A, the first charge accumulation period is set by the electronic shutter function to a period of time T1, starting from a time that is a delay time (first delay time) D1 after the rising timing of the trigger signal.

[0039] The transfer of the electric charges accumulated in each pixel of the first region 21A to the first output unit 23A (first vertical transfer) is performed during a period starting from the middle of the first charge accumulation period to the end of the first charge accumulation period. The output of the first electric signal from the first output unit 23A (first horizontal transfer) is performed after the charge accumulation and first vertical transfer of each pixel of the first region 21A over the first charge accumulation period have been performed K1 times.

[0040] In the second region 21B, the second charge accumulation period is set by the electronic shutter function to a period of time T2 starting from a time that is a delay time (second delay time) D2 after the rising timing of the trigger signal.

[0041] The transfer of the charges accumulated in each pixel of the second region 21B to the second output unit 23B (second vertical transfer) is performed during a period starting from the middle of the second charge accumulation period to the end of the second charge accumulation period. The output of the second electrical signal from the second output unit 23B (second horizontal transfer) is performed after the charge accumulation and first vertical transfer of each pixel of the second region 21B over the second charge accumulation period have been performed K2 times.

[0042] In the example shown in this figure, the first charge accumulation period is a period that includes the peak of the fluorescent light pulse and has a relatively high fluorescent light intensity, while the second charge accumulation period is a period that does not include the peak of the fluorescent light pulse and has a relatively low fluorescent light intensity. In this case, it is preferable to set K2 larger than K1. Alternatively, it is also preferable to set the time T2 of the second charge accumulation period longer than the time T1 of the first charge accumulation period.

[0043] As shown in this figure, in the case of the measured light consisting of repeatedly occurring optical pulses, if the period of the repeated occurrence of the optical pulses is short (if the period of the trigger signal is short), an optical pulse may be generated during the first horizontal transfer period when the first output section 23A is outputting the first electrical signal, and an optical pulse may be generated during the second horizontal transfer period when the second output section 23B is outputting the second electrical signal.

[0044] During the first horizontal transfer period when the first output section 23A is outputting the first electrical signal, even if the pixels in the first region 21A receive a light pulse and generate an electric charge, the pixels are forced to discharge the electric charge without accumulating it. Similarly, during the second horizontal transfer period when the second output section 23B is outputting the second electrical signal, even if the pixels in the second region 21B receive a light pulse and generate an electric charge, the pixels are forced to discharge the electric charge without accumulating it.

[0045] This situation occurs because the number of columns N in the pixel array of a photodetector generally used in spectroscopic measurements is large, and the time required to output an electrical signal corresponding to the amount of charge accumulated in each column (horizontal transfer time) is long, making it difficult to efficiently acquire the spectrum of the light under measurement.

[0046] In order to address this problem, in this embodiment, the number of rows M1 and M2 in the pixel array is relatively small, and therefore the time required for vertical transfer is relatively short. This is taken advantage of, and after charge accumulation and first vertical transfer of each pixel is performed multiple times in the first region 21A, the first horizontal transfer is performed in the first output section 23A, and after charge accumulation and second vertical transfer of each pixel is performed multiple times in the second region 21B, the second horizontal transfer is performed in the second output section 23B.

[0047] By doing so, it is possible to reduce the frequency at which the pixel is forced to discharge the charge generated by receiving a light pulse without accumulating it, thereby making it possible to efficiently acquire the spectrum of the light to be measured.

[0048] The photodetector 20 used in this embodiment has a light receiving section 21 having a first region 21A and a second region 21B, a first output section 23A, and a second output section 23B formed on a common semiconductor substrate. Therefore, compared to a case where two sets of optical systems and photodetectors are used to acquire two spectra, this embodiment has smaller optical differences between devices and makes it easier to correct the effects of optical distortion and temperature drift.

[0049] Furthermore, in this embodiment, it is easy to synchronize the operations for acquiring the two spectra, the system can be constructed easily, and the influence of timing errors due to jitter, etc. is small. Furthermore, this embodiment is advantageous in terms of miniaturization and low cost.

[0050] 6( a) and 6(b) are timing charts illustrating another example of control of the operation of the photodetector 20 by the control unit 30. These figures show the operation of the first region 21A and the first output unit 23A, but the operation of the second region 21B and the second output unit 23B is similar. These figures show, from top to bottom, the trigger signal waveform, the fluorescent light pulse waveform, the electronic shutter operation of the first region 21A (accumulation / discharge of pixel charge), the transfer of charge accumulated in each pixel of the first region 21A to the first output unit 23A (first vertical transfer), and the output of the first electrical signal from the first output unit 23A (first horizontal transfer).

[0051] In the operation example shown in these figures, the charges accumulated in each pixel of some rows close to the first output section 23A of the pixel array of M1 rows and N columns in the first region 21A are sequentially transferred to the first output section 23A (first vertical transfer), and then the charges of all pixels in the first region 21A are discharged using the electronic shutter function.

[0052] 6A shows a case where the period of the trigger signal is relatively short and the number of rows for which charges are vertically transferred is relatively small. FIG. 6B shows a case where the period of the trigger signal is relatively long and the number of rows for which charges are vertically transferred is relatively large. As shown in these figures, it is preferable to set the number of rows for which charges are vertically transferred, adjust the time T1 of the first charge accumulation period, adjust the time required for vertical transfer, and adjust the number of charge accumulations and vertical transfers K1 per horizontal transfer, depending on the period of the trigger signal.

[0053] That is, when the period of the trigger signal is short, the number of rows for vertically transferring electric charges is reduced, the time T1 of the first charge accumulation period is shortened, the vertical transfer time is shortened, and K1 is increased. In this way, by setting the number of rows for vertically transferring electric charges according to the period of repeated generation of light pulses (according to the period of the trigger signal), the spectrum of the light under measurement can be acquired more efficiently.

[0054] 7 is a timing chart illustrating another example of setting the charge accumulation period using the electronic shutter function, which shows, from top to bottom, a first trigger signal waveform, a first fluorescent light pulse waveform, a second trigger signal waveform, a second fluorescent light pulse waveform, accumulation / discharge of pixel charges in the first region 21A, an electronic shutter operation for the first region 21A, accumulation / discharge of pixel charges in the second region 21B, and an electronic shutter operation for the second region 21B.

[0055] In the example shown in this figure, the first excitation light pulse is irradiated onto the object S at the rising edge of the first trigger signal, and a first fluorescent pulse is generated after this edge. Furthermore, the second excitation light pulse is irradiated onto the object S at the rising edge of the second trigger signal, and a second fluorescent pulse is generated after this edge. The fluorescent intensities of the first fluorescent pulse and the second fluorescent pulse gradually increase from the rising edge of the trigger signal, reach a peak, and then gradually decrease.

[0056] In the example shown in this figure, a first trigger signal and a second trigger signal are output from the external control unit 40 to the control unit 30. The control unit 30 controls the operation of the photodetector 20 based on the first trigger signal and the second trigger signal synchronized with the timing of generation of the optical pulses of the first and second measured light, respectively.

[0057] In the first region 21A, the electronic shutter is open during a period including the peak of the first fluorescent pulse (first charge accumulation period), allowing charge generated by the pixels to accumulate, while in the second region 21B, the electronic shutter is open during a period including the peak of the second fluorescent pulse (second charge accumulation period), allowing charge generated by the pixels to accumulate.

[0058] The first charge accumulation period and the second charge accumulation period each start at a time delayed by a certain time from the rising edge of the trigger signal, and end at a time delayed by a certain time from the first charge accumulation period. During the period in which the electronic shutter is closed, even if a charge is generated in the pixel, the charge is discharged without being accumulated.

[0059] In this way, the first charge accumulation period and the second charge accumulation period may have different start times and end times. The first charge accumulation period and the second charge accumulation period may partially overlap each other, or may not overlap. Furthermore, the first charge accumulation period may be a period that includes the peak of the second fluorescent light pulse, and the second charge accumulation period may be a period that includes the peak of the first fluorescent light pulse.

[0060] In the above description of the embodiment, an example of a repeatedly generated light pulse is a fluorescent pulse that is repeatedly generated in an object by repeatedly irradiating the object with an excitation light pulse. However, the light pulse that is the measurement target of the spectroscopic measurement device and spectroscopic measurement method of the present embodiment is not limited to this. For example, the spectroscopic measurement device and spectroscopic measurement method of the present embodiment can also be used to measure the spectrum of a light pulse that is repeatedly generated in synchronization with pulsed plasma in a process of dry etching an object using a plasma process.

[0061] The spectroscopic measurement device and spectroscopic measurement method are not limited to the above-described embodiment and configuration examples, and various modifications are possible.

[0062] The spectroscopic measurement device of the first aspect according to the above embodiment includes: (1) an optical system that disperses light to be measured, which is composed of repeatedly generated light pulses, to form a spectral image; (2) a photodetector that detects the spectral image; and (3) a control unit that controls the operation of the photodetector. (4) The photodetector includes: (a) a light-receiving unit in which a plurality of pixels, each generating a charge in response to incident light, are two-dimensionally arranged in (M1+M2) rows and N columns (M1, M2, and N are each an integer of 2 or greater) on a light-receiving surface, the light-receiving surface being divided into a first region of M1 rows and N columns and a second region of M2 rows and N columns, and the spectral image is formed on the light-receiving surface so that the wavelength axis of the spectral image is parallel to the row direction of the light-receiving surface; (b) a first output unit that integrates, for each column, the charges generated and accumulated by each pixel in the first region during a first charge accumulation period, and outputs a first electrical signal corresponding to the integrated amount of charge for each column; and (c) a second output unit that integrates, for each column, the charges generated by each pixel in the second region during a second charge accumulation period. and a second output unit that integrates the accumulated charge for each column and outputs a second electrical signal corresponding to the amount of accumulated charge for each column; (5) the control unit, where either K1 or K2 is an integer of 1 or greater and the other is an integer of 2 or greater, (a) synchronizes with the generation timing of each optical pulse of the light to be measured to cause each pixel in the first region to accumulate charge over a first charge accumulation period and transfer the charge accumulated by each pixel in the first region to the first output unit K1 times, and then outputs a first electrical signal corresponding to the amount of accumulated charge for each column K1 times from the first output unit; (b) synchronizes with the generation timing of each optical pulse of the light to be measured to cause each pixel in the second region to accumulate charge over a second charge accumulation period and transfer the charge accumulated by each pixel in the second region to the second output unit K2 times, and then outputs a second electrical signal corresponding to the amount of accumulated charge for each column K2 times from the second output unit.

[0063] In the spectroscopic measurement device of the second aspect, in the configuration of the first aspect, the control unit may be configured to perform charge accumulation and charge transfer in the first region and output of the first electrical signal from the first output unit, and charge accumulation and charge transfer in the second region and output of the second electrical signal from the second output unit, independently of each other.

[0064] In the spectroscopic measurement device of the third aspect, in the configuration of the first or second aspect, the control unit may be configured to make the first charge accumulation period and the second charge accumulation period different from each other.

[0065] In the spectroscopic measurement device of the fourth aspect, in the configuration of any of the first to third aspects, the control unit may be configured to set a period including a peak of each optical pulse of the measured light as a first charge accumulation period, and to set a period not including a peak of each optical pulse of the measured light as a second charge accumulation period.

[0066] In the spectrometer of the fifth aspect, in the configuration of the fourth aspect, the control unit may be configured to set K2 to be greater than K1.

[0067] In the spectroscopic measurement device of the sixth aspect, in the configuration of the fourth or fifth aspect, the control unit may be configured to set the second charge accumulation period longer than the first charge accumulation period.

[0068] In the spectroscopic measurement device of the seventh aspect, in the configuration of any of the first to third aspects, the measured light may include a first measured light and a second measured light, and the control unit may be configured to set a period including a peak of each optical pulse of the first measured light as a first charge accumulation period, and to set a period including a peak of each optical pulse of the second measured light as a second charge accumulation period.

[0069] In the spectroscopic measurement device of the eighth aspect, in the configuration of any of the first to seventh aspects, the photodetector may have an electronic shutter function that selects either accumulation or discharge of the charge generated by each pixel, and the control unit may be configured to use the electronic shutter function of the photodetector to set the first charge accumulation period and the second charge accumulation period.

[0070] In the spectroscopic measurement device of the ninth aspect, in the configuration of any of the first to eighth aspects, the photodetector has an electronic shutter function that selects either accumulation or discharge of the charge generated by each pixel, and the control unit may utilize the electronic shutter function of the photodetector to transfer the charge accumulated by each pixel for some rows of the first region to the first output unit and then discharge the charge from all pixels in the first region, and to transfer the charge accumulated by each pixel for some rows of the second region to the second output unit and then discharge the charge from all pixels in the second region.

[0071] In the spectroscopic measurement device of a tenth aspect, in the configuration of any one of the first to ninth aspects, the photodetector may be a CCD image sensor.

[0072] A spectroscopic measurement method of a first aspect according to the above embodiment uses a photodetector having a light receiving portion in which a plurality of pixels, each generating an electric charge in response to incident light, are two-dimensionally arranged in (M1+M2) rows and N columns (M1, M2, and N are each an integer of 2 or more) on a light receiving surface, and the light receiving surface is divided into a first region of M1 rows and N columns and a second region of M2 rows and N columns, the spectroscopic measurement method comprising: (1) a spectroscopic step of spectroscopically measuring light to be measured, which is made up of repeatedly occurring light pulses, to form a spectral image; and (2) a detection step of detecting the spectral image by the photodetector, and (3) in the spectroscopic step, the spectral image is formed on the light receiving surface so that the wavelength axis of the spectral image is parallel to the row direction of the light receiving surface, 4) In the detection step, one of K1 and K2 is an integer of 1 or greater, and the other is an integer of 2 or greater, and (a) in synchronization with the timing of generation of each optical pulse of the measured light, charge accumulation in each pixel of the first region over a first charge accumulation period and transfer of the charge accumulated by each pixel of the first region are performed K1 times, and then a first electrical signal corresponding to the amount of charge accumulated for each column K1 times is output; and (b) in synchronization with the timing of generation of each optical pulse of the measured light, charge accumulation in each pixel of the second region over a second charge accumulation period and transfer of the charge accumulated by each pixel of the second region are performed K2 times, and then a second electrical signal corresponding to the amount of charge accumulated for each column K2 times is output.

[0073] In the spectroscopic measurement method of the second aspect, in the configuration of the first aspect, in the detection step, charge accumulation and charge transfer in the first region and output of the first electrical signal, and charge accumulation and charge transfer in the second region and output of the second electrical signal may be performed independently of each other.

[0074] In the spectroscopic measurement method of the third aspect, in the configuration of the first or second aspect, the first charge accumulation period and the second charge accumulation period may be different from each other in the detecting step.

[0075] In the spectroscopic measurement method of the fourth aspect, in the configuration of any one of the first to third aspects, in the detection step, a period including a peak of each optical pulse of the measured light may be set as a first charge accumulation period, and a period not including a peak of each optical pulse of the measured light may be set as a second charge accumulation period.

[0076] The spectroscopic measurement method of the fifth aspect may be configured in the configuration of the fourth aspect, such that K2 is set to be greater than K1 in the detection step.

[0077] In the spectroscopic measurement method of the sixth aspect, in the configuration of the fourth or fifth aspect, the second charge accumulation period may be set longer than the first charge accumulation period in the detecting step.

[0078] In the spectroscopic measurement method of the seventh aspect, in the configuration of any of the first to third aspects, the measured light may include a first measured light and a second measured light, and in the detection step, a period including a peak of each optical pulse of the first measured light may be set as a first charge accumulation period, and a period including a peak of each optical pulse of the second measured light may be set as a second charge accumulation period.

[0079] In the spectroscopic measurement method of the eighth aspect, in the configuration of any one of the first to seventh aspects, in the detection step, a photodetector having an electronic shutter function that selects either accumulation or discharge of the charge generated by each pixel may be used, and the first charge accumulation period and the second charge accumulation period may be set using the electronic shutter function of the photodetector.

[0080] In the spectroscopic measurement method of the ninth aspect, in the configuration of any of the first to eighth aspects, in the detection step, a photodetector having an electronic shutter function that selects either accumulation or discharge of the charge generated by each pixel is used, and the electronic shutter function of the photodetector is used to transfer the charge accumulated by each pixel for some rows of the first region to a first output unit, and then discharge the charge of all pixels in the first region, and to transfer the charge accumulated by each pixel for some rows of the second region to a second output unit, and then discharge the charge of all pixels in the second region.

[0081] In the spectroscopic measurement method of the tenth aspect, in the configuration of any one of the first to ninth aspects, the photodetector may be a CCD image sensor.

[0082] The embodiments can be used as a spectroscopic measurement device and a spectroscopic measurement method that can efficiently acquire the spectrum of light to be measured, which is made up of optical pulses that are repeatedly generated at high speed, under various exposure conditions with a simple configuration.

[0083] 1...spectroscopic measurement device, 10...optical system, 20...photodetector, 21...light receiving section, 21A...first region, 21B...second region, 22...pixel, 23A...first output section, 23B...second output section, 30...control section, 40...external control section, S...object, P...spectroscopic image.

Claims

1. An optical system that forms a spectral image by dispersing light to be measured, which is composed of repeatedly generated optical pulses; a photodetector that detects the spectral image; and a control unit that controls the operation of the photodetector, wherein the photodetector includes: a photoreceptor in which a plurality of pixels, each generating an electric charge in response to incident light, are two-dimensionally arranged in (M1+M2) rows and N columns (M1, M2, and N are each an integer of 2 or greater) on a light-receiving surface, the light-receiving surface being divided into a first region of M1 rows and N columns and a second region of M2 rows and N columns, and the spectral image is formed on the light-receiving surface so that the wavelength axis of the spectral image is parallel to the row direction of the light-receiving surface; a first output unit that integrates, for each column, the electric charges generated and accumulated by each pixel in the first region during a first charge accumulation period, and outputs a first electrical signal corresponding to the amount of electric charge integrated for each column; and a second output unit that integrates, for each column, the electric charges generated and accumulated by each pixel in the second region during a second charge accumulation period, and outputs a second electrical signal corresponding to the amount of electric charge integrated for each column. the control unit performs charge accumulation in each pixel of the first region over the first charge accumulation period in synchronization with the generation timing of each optical pulse of the measured light and transfers the charge accumulated by each pixel of the first region to the first output unit K1 times, and then outputs the first electrical signal from the first output unit according to the amount of charge accumulated per column K1 times; and performs charge accumulation in each pixel of the second region over the second charge accumulation period in synchronization with the generation timing of each optical pulse of the measured light and transfers the charge accumulated by each pixel of the second region to the second output unit K2 times, and then outputs the second electrical signal from the second output unit according to the amount of charge accumulated per column K2 times.

2. The spectroscopic measurement device of claim 1, wherein the control unit performs charge accumulation and charge transfer in the first region and output of the first electrical signal from the first output unit, and charge accumulation and charge transfer in the second region and output of the second electrical signal from the second output unit, independently of each other.

3. The spectrometer according to claim 1 or 2, wherein the control unit makes the first charge accumulation period and the second charge accumulation period different from each other.

4. A spectroscopic measurement device according to any one of claims 1 to 3, wherein the control unit defines a period including the peak of each optical pulse of the measured light as the first charge accumulation period, and a period not including the peak of each optical pulse of the measured light as the second charge accumulation period.

5. The spectrometer according to claim 4, wherein the control unit sets K2 to be greater than K1.

6. The spectrometer according to claim 4 or 5, wherein the control unit sets the second charge accumulation period to be longer than the first charge accumulation period.

7. The spectroscopic measurement device according to any one of claims 1 to 3, wherein the light to be measured includes first light to be measured and second light to be measured, and the control unit determines a period including a peak of each optical pulse of the first light to be the first charge accumulation period, and a period including a peak of each optical pulse of the second light to be the second charge accumulation period.

8. A spectroscopic measurement device according to any one of claims 1 to 7, wherein the photodetector has an electronic shutter function that selects between accumulating and discharging the charge generated by each pixel, and the control unit uses the electronic shutter function of the photodetector to set the first charge accumulation period and the second charge accumulation period.

9. The spectroscopic measurement device according to any one of claims 1 to 8, wherein the photodetector has an electronic shutter function that selects between accumulating and discharging the charge generated by each pixel, and the control unit utilizes the electronic shutter function of the photodetector to transfer the charge accumulated by each pixel for a portion of rows in the first region to the first output unit, and then discharge the charge from all pixels in the first region, and to transfer the charge accumulated by each pixel for a portion of rows in the second region to the second output unit, and then discharge the charge from all pixels in the second region.

10. A spectroscopic measurement method using a photodetector having a light receiving portion in which a plurality of pixels, each generating an electric charge in response to incident light, are two-dimensionally arranged in (M1+M2) rows and N columns (M1, M2, and N are each an integer of 2 or greater) on a light receiving surface, and the light receiving surface is divided into a first region of M1 rows and N columns and a second region of M2 rows and N columns, the method comprising: a spectroscopic step of spectroscopically measuring light to be measured, which is made up of repeatedly occurring light pulses, to form a spectral image; and a detection step of detecting the spectral image with the photodetector, wherein in the spectroscopic step, the spectral image is formed on the light receiving surface so that the wavelength axis of the spectral image is parallel to the row direction of the light receiving surface, and in the detection step, one of K1 and K2 is an integer of 1 or greater and the other is an integer of 2 or greater, a spectroscopic measurement method comprising: storing charge in each pixel of the first region over a first charge accumulation period in synchronization with the generation timing of each optical pulse of the measured light; and transferring the charge stored by each pixel of the first region K1 times; and then outputting a first electrical signal corresponding to the amount of charge accumulated for each column K1 times; and storing charge in each pixel of the second region over a second charge accumulation period in synchronization with the generation timing of each optical pulse of the measured light; and then outputting a second electrical signal corresponding to the amount of charge accumulated for each column K2 times.

11. The spectroscopic measurement method according to claim 10, wherein in the detection step, a period including a peak of each optical pulse of the measured light is defined as the first charge accumulation period, and a period not including a peak of each optical pulse of the measured light is defined as the second charge accumulation period.

12. The spectroscopic measurement method according to claim 10, wherein the light to be measured includes first light to be measured and second light to be measured, and in the detection step, a period including a peak of each light pulse of the first light to be measured is defined as the first charge accumulation period, and a period including a peak of each light pulse of the second light to be measured is defined as the second charge accumulation period.

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