Spectroscopic measurement device and spectroscopic measurement method

Abstract

To provide a spectrometry device capable of efficiently acquiring a spectrum of light to be measured composed of light pulses repeatedly generated at high speed under various exposure conditions with a simple configuration.SOLUTION: A spectroscopic measurement device 1 includes an optical system 10, a light detector 20, and a control unit 30, and acquires a spectrum of light to be measured consisting of repeatedly generated light pulses. A light receiving unit 21 of the light detector 20 has a light receiving surface on 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. In synchronization with light pulse generation timing, the control unit 30 controls respective operations of charge accumulation of each pixel in the first region 21A, transferring of charge accumulated by each pixel in the first region 21A to a first outputting unit 23A, and outputting of a first electric signal from the first outputting unit 23A. The control unit 30 also controls respective operations of the second region 21B and a second output device 23B in the same manner.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a spectroscopic measurement device and a spectroscopic measurement method. [Background technology]

[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 multiple 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 technology, 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 (for example, 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 where 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. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2018-174324 Summary of the Invention [Problem to be solved by the invention]

[0007] In the case of measured light consisting of repetitive optical pulses, such as the fluorescence example described above, it is difficult to efficiently acquire the spectrum of the measured light under various exposure conditions when the repetitive optical pulses occur at a short period. Photodetectors used for spectroscopic measurements generally have a large number of pixel columns, and it takes a long time to output an electrical signal corresponding to the integrated charge amount for each column. During the period when this electrical signal is being output, even if a pixel receiving an optical pulse generates an electric charge, the pixel must discharge the electric charge without accumulating it. To address this issue, it is conceivable to use a photodetector designed to operate at a high-speed clock; however, realizing such a photodetector is difficult in terms of device design and noise design.

[0008] The present invention has been made to solve the above problems, and aims to provide a spectroscopic measurement device and a spectroscopic measurement method that can efficiently acquire the spectrum of measured light consisting of optical pulses that are repeatedly generated at high speed under various exposure conditions with a simple configuration. [Means for solving the problem]

[0009] A first aspect of the spectroscopic measurement device of the present invention includes an optical system that disperses measured light consisting of repeatedly generated optical pulses to form a spectral image, a photodetector that detects the spectral image, and a control unit that controls the operation of the photodetector. The photodetector includes: (1) 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 photoreceptor surface, the photoreceptor 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 photoreceptor surface so that the wavelength axis of the spectral image is parallel to the row direction of the photoreceptor surface; (2) 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 (3) 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 integrated amount of electric charge for each column. The control unit, where 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, (1) causes each pixel in the first region to accumulate charge over a first charge accumulation period in synchronization with the timing of generation of each optical pulse of the light to be measured 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 from the first output unit according to the amount of charge accumulated for each column K1 times, and (2) causes each pixel in the second region to accumulate charge over a second charge accumulation period in synchronization with the timing of generation of each optical pulse of the light to be measured K2 times 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 from the second output unit according to the amount of charge accumulated for each column K2 times.

[0010] In a second aspect of the spectroscopic measurement device of the present invention, in addition to the first aspect, the control unit causes 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, to be performed independently of each other.

[0011] In a third aspect of the spectroscopic measurement device of the present invention, in addition to the first or second aspect, the control unit makes the first charge accumulation period and the second charge accumulation period different from each other.

[0012] In a fourth aspect of the spectroscopic measurement device of the present invention, in addition to any one of the first to third aspects, the control unit determines a period including a peak of each optical pulse of the measured light as a first charge accumulation period, and determines a period not including a peak of each optical pulse of the measured light as a second charge accumulation period.

[0013] In a fifth aspect of the spectroscopic measurement device of the present invention, in addition to the fourth aspect, the control unit sets K2 to be larger than K1.

[0014] In a sixth aspect of the spectroscopic measurement device of the present invention, in addition to the fourth or fifth aspect, the control unit sets the second charge accumulation period to be longer than the first charge accumulation period.

[0015] In a seventh aspect of the spectroscopic measurement device of the present invention, in addition to any of the first to third aspects, the measured light includes first measured light and second measured light, and the control unit determines a period including a peak of each optical pulse of the first measured light as a first charge accumulation period, and determines a period including a peak of each optical pulse of the second measured light as the second charge accumulation period.

[0016] In an eighth aspect of the spectroscopic measurement device of the present invention, in addition to any of the first to seventh 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 uses the electronic shutter function of the photodetector to set the first charge accumulation period and the second charge accumulation period.

[0017] In a ninth aspect of the spectroscopic measurement device of the present invention, in addition to any of the first to eighth aspects, 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 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.

[0018] A first aspect of the spectroscopic measurement method of the present invention uses a photodetector having a light-receiving section 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 includes a spectroscopic step of spectroscopically dispersing measured light consisting of repeatedly occurring optical pulses to form a spectral image, and a detection step of detecting the spectral image with the photodetector. 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. 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, (1) 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 (2) 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.

[0019] In a second aspect of the spectroscopic measurement method of the present invention, in addition to 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 are performed independently of each other.

[0020] In a third aspect of the spectroscopic measurement method of the present invention, in addition to the first or second aspect, the first charge accumulation period and the second charge accumulation period are made different from each other in the detection step.

[0021] In a fourth aspect of the spectroscopic measurement method of the present invention, in addition to 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 is defined as a first charge accumulation period, and a period not including a peak of each optical pulse of the measured light is defined as a second charge accumulation period.

[0022] In a fifth aspect of the spectroscopic measurement method of the present invention, in addition to the fourth aspect, K2 is set to be larger than K1 in the detection step.

[0023] In a sixth aspect of the spectroscopic measurement method of the present invention, in addition to the fourth or fifth aspect, the second charge accumulation period is set longer than the first charge accumulation period in the detecting step.

[0024] In a seventh aspect of the spectroscopic measurement method of the present invention, in addition to 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 is set as the first charge accumulation period, and a period not including a peak of each optical pulse of the measured light is set as the second charge accumulation period.

[0025] In an eighth aspect of the spectroscopic measurement method of the present invention, in addition to 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 is used, and the first charge accumulation period and the second charge accumulation period are set using the electronic shutter function of the photodetector.

[0026] In a ninth aspect of the spectroscopic measurement method of the present invention, in addition to 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 from 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 from all pixels in the second region.

[0027] In the spectroscopic measurement device or spectroscopic measurement method of the present invention, the photodetector may be a CCD image sensor. [Effects of the Invention]

[0028] According to the present invention, the spectrum of light to be measured, which is made up of optical pulses repeatedly generated at high speed, can be efficiently acquired under various exposure conditions with a simple configuration. [Brief explanation of the drawings]

[0029] [Figure 1] FIG. 1 is a diagram showing the configuration of a spectroscopic measurement device 1. [Figure 2] FIG. 2 is a diagram showing the configuration of the photodetector 20. As shown in FIG. [Figure 3] FIG. 3 is a diagram showing the configuration of the light receiving section 21 of the photodetector 20. As shown in FIG. [Figure 4] FIG. 4 is a timing chart illustrating an example of setting the charge accumulation period using the electronic shutter function. [Figure 5] FIG. 5 is a timing chart illustrating an example of control of the operation of the photodetector 20 by the control unit 30. In FIG. [Figure 6] 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. In FIG. [Figure 7] FIG. 7 is a timing chart illustrating another example of setting the charge accumulation period using the electronic shutter function. DETAILED DESCRIPTION OF THE INVENTION

[0030] Hereinafter, embodiments of the present invention 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.

[0031] 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 made up of repeatedly occurring light pulses. For example, the light to be measured is made up of fluorescent pulses that are repeatedly generated in the object S by repeatedly irradiating the object S with excitation light pulses.

[0032] 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 splits 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.

[0033] The photodetector 20 has a light-receiving surface in which a plurality of pixels, each generating 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. The photodetector 20 is preferably thinned by grinding the back surface of the semiconductor substrate (the surface opposite to the image sensor surface) and is capable of highly sensitive light detection in a wide wavelength range. 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] The light receiving unit 21 has a light receiving surface in which a plurality of pixels 22, each of which generates an electric charge in response to incident light, is 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. 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.

[0038] 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.

[0039] In the second region 21B, each pixel accumulates electric charges generated in response to incident light over a second charge accumulation period and transfers the accumulated electric charges column by column in the column direction (charge transfer direction A2) to the second output section 23B. The second output section 23B integrates, for each column, the electric charges generated and accumulated by each pixel in the second region 21B during the second charge accumulation period and outputs, as second spectral data, a second electric signal corresponding to the amount of accumulated electric charges for each column.

[0040] 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.

[0041] 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 charges accumulated in each pixel in the first region 21A to the first output section 23A (hereinafter referred to as "first vertical transfer"), and output of a first electrical signal from the first output section 23A (hereinafter referred to as "first horizontal transfer"). The control unit 30 also controls the operations of charge accumulation in each pixel in the second region 21B, transfer of the charges accumulated in each pixel in the second region 21B to the second output section 23B (hereinafter referred to as "second vertical transfer"), and output of a second electrical signal from the second output section 23B (hereinafter referred to as "second horizontal transfer"). The control unit 30 causes 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.

[0042] 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 light under measurement, 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 light under measurement, 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.

[0043] The spectroscopic measurement method of this embodiment includes a spectroscopic step of dispersing the light to be measured, which is made up of repeatedly occurring optical pulses, using the optical system 10 to form a spectral image, 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.

[0044] 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 using 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.

[0045] 4 is a timing chart illustrating an example of setting a charge accumulation period using the electronic shutter function. From top to bottom, the diagram shows a trigger signal waveform, a fluorescent light pulse waveform, accumulation / discharge of pixel charges in the first region 21A, electronic shutter operation in the first region 21A, accumulation / discharge of pixel charges in the second region 21B, and electronic shutter operation in the second region 21B.

[0046] 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 pulse is generated from this point onwards. The fluorescent intensity gradually increases from the rising edge of the trigger signal, reaches a peak, and then gradually decreases.

[0047] 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 charge generated by the pixels is accumulated. In the second region 21B, the electronic shutter is open during the period following the peak of the fluorescent pulse (second charge accumulation period), and charge generated by the pixels is accumulated. The first and second charge accumulation periods 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 that time. During the period when the electronic shutter is closed, even if charge is generated by the pixels, the charge is discharged without being accumulated.

[0048] 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, 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.

[0049] 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, an 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 section 23A (first vertical transfer), output of a first electrical signal from the first output section 23A (first horizontal transfer), an 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 section 23B (second vertical transfer), and output of a second electrical signal from the second output section 23B (second horizontal transfer).

[0050] 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 pulse is generated from this point onwards. The fluorescent intensity gradually increases from the rising edge of the trigger signal, reaches a peak, and then gradually decreases.

[0051] In the first region 21A, the first charge accumulation period is set by an 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 edge of the trigger signal. The transfer (first vertical transfer) of the charges accumulated in each pixel of the first region 21A to the first output section 23A begins midway through the first charge accumulation period and continues until the end of the first charge accumulation period. The output (first horizontal transfer) of the first electrical signal from the first output section 23A is performed after the charge accumulation and first vertical transfer of each pixel in the first region 21A over the first charge accumulation period have been performed K1 times.

[0052] 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 edge of the trigger signal. The transfer of the charges accumulated by each pixel in the second region 21B to the second output section 23B (second vertical transfer) is performed during the period 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 section 23B (second horizontal transfer) is performed after the charge accumulation and first vertical transfer of each pixel in the second region 21B over the second charge accumulation period have been performed K2 times.

[0053] 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.

[0054] As shown in this figure, when the light under measurement is composed of repetitive optical pulses and the period of the repetitive generation of the optical pulses is short (when the period of the trigger signal is short), optical pulses may occur during the first horizontal transfer period when the first output section 23A is outputting the first electrical signal, and optical pulses may occur during the second horizontal transfer period when the second output section 23B is outputting the second electrical signal. During the first horizontal transfer period when the first output section 23A is outputting the first electrical signal, even if pixels in the first region 21A receive optical pulses and generate electric charges, they are forced to discharge the electric charges without accumulating them. Similarly, during the second horizontal transfer period when the second output section 23B is outputting the second electrical signal, even if pixels in the second region 21B receive optical pulses and generate electric charges, they are forced to discharge the electric charges without accumulating them. 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.

[0055] To address this problem, in this embodiment, taking advantage of the fact that 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, charge accumulation and first vertical transfer are performed multiple times for each pixel in the first region 21A, and then the first horizontal transfer is performed in the first output section 23A, and charge accumulation and second vertical transfer are performed multiple times for each pixel in the second region 21B, and then the second horizontal transfer is performed in the second output section 23B. This reduces the frequency with which pixels are forced to discharge charges generated by receiving light pulses without accumulating them, thereby enabling efficient acquisition of the spectrum of the light under measurement.

[0056] 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 using two sets of optical systems and photodetectors to acquire two spectra, this embodiment has smaller optical differences between individual devices and is easier to correct for the effects of optical distortion and temperature drift. Furthermore, this embodiment also makes it easy to synchronize the operations for acquiring the two spectra, simplifying system construction and minimizing the effects of timing errors due to jitter and the like. Furthermore, this embodiment is advantageous in terms of miniaturization and cost reduction.

[0057] 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 illustrate 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 charges), the transfer of charges accumulated by each pixel in the first region 21A to the first output unit 23A (first vertical transfer), and the output of a first electrical signal from the first output unit 23A (first horizontal transfer). In the operational example shown in these figures, charges accumulated by each pixel in some rows close to the first output unit 23A of the M1-row, N-column pixel array in the first region 21A are sequentially transferred to the first output unit 23A (first vertical transfer), and then the charges of all pixels in the first region 21A are discharged using the electronic shutter function.

[0058] FIG. 6(a) 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. 6(b) 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 duration 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. That is, when the period of the trigger signal is short, the number of rows for which charges are vertically transferred is reduced, the duration 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 which charges are vertically transferred depending on the period of the repeated generation of the optical pulse (depending on the period of the trigger signal), the spectrum of the measured light can be acquired more efficiently.

[0059] 7 is a timing chart illustrating another example of setting the charge accumulation period using the electronic shutter function. From top to bottom, this diagram shows 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 in the first region 21A, accumulation / discharge of pixel charges in the second region 21B, and an electronic shutter operation in the second region 21B.

[0060] 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 the 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 the 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.

[0061] In the example shown in this figure, a first trigger signal and a second trigger signal are output from an 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 optical pulse generation timing of the first measured light and the second measured light, respectively.

[0062] In the first region 21A, the electronic shutter is open during the period including the peak of the first fluorescent pulse (first charge accumulation period), and charge generated by the pixels is accumulated. In the second region 21B, the electronic shutter is open during the period including the peak of the second fluorescent pulse (second charge accumulation period), and charge generated by the pixels is accumulated. 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 that time. During the period when the electronic shutter is closed, even if charge is generated by the pixels, the charge is discharged without being accumulated.

[0063] 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, 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.

[0064] 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. [Explanation of symbols]

[0065] 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.

Claims

1. an optical system for dispersing light to be measured, which is made up of repeatedly generated optical pulses, to form a spectral image; a photodetector for detecting the spectral image; and a control unit for controlling the operation of the photodetector; The photodetector 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; a first output section that integrates, for each column, the electric charges generated and accumulated by each pixel in the first region during a first electric charge accumulation period, and outputs a first electric signal corresponding to the integrated amount of electric charges for each column; a second output section that integrates, for each column, the electric charges generated and accumulated by each pixel in the second region during a second electric charge accumulation period, and outputs a second electric signal corresponding to the integrated amount of electric charges for each column; Including, The control unit One of K1 and K2 is an integer of 1 or more, and the other is an integer of 2 or more, 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 light to be measured and transfer of the charge accumulated by each pixel of the first region to the first output unit are performed K1 times, and thereafter the first electrical signal corresponding to the charge integration amount for each column K1 times is output from the first output unit; 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 light to be measured and transfer of the charges accumulated by each pixel of the second region to the second output unit are performed K2 times, and thereafter the second electrical signal corresponding to the charge accumulation amount for each column K2 times is output from the second output unit. Spectrometer.

2. the control unit causes 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. The spectroscopic measurement device according to claim 1 .

3. the control unit makes the first charge accumulation period and the second charge accumulation period different from each other; The spectroscopic measurement device according to claim 1 .

4. the control unit defines a period including a peak of each optical pulse of the light under measurement as the first charge accumulation period, and defines a period not including a peak of each optical pulse of the light under measurement as the second charge accumulation period. The spectroscopic measurement device according to claim 1 .

5. The control unit sets K2 to be larger than K1. The spectroscopic measurement device according to claim 4 .

6. the control unit sets the second charge accumulation period to be longer than the first charge accumulation period; The spectroscopic measurement device according to claim 4 .

7. the light under measurement includes first light under measurement and second light under measurement, the control unit determines a period including a peak of each optical pulse of the first measured light as the first charge accumulation period, and determines a period including a peak of each optical pulse of the second measured light as the second charge accumulation period. The spectroscopic measurement device according to claim 1 .

8. the photodetector has an electronic shutter function for selecting either accumulation or discharge of electric charge generated by each pixel; the control unit sets the first charge accumulation period and the second charge accumulation period by utilizing an electronic shutter function of the photodetector. The spectroscopic measurement device according to claim 1 .

9. the photodetector has an electronic shutter function for selecting either accumulation or discharge of electric charge generated by each pixel; the control unit uses an electronic shutter function of the photodetector to transfer the charges accumulated in each pixel for a portion of rows in the first region to the first output unit, and then drains the charges of all pixels in the first region, and transfers the charges accumulated in each pixel for a portion of rows in the second region to the second output unit, and then drains the charges of all pixels in the second region. The spectroscopic measurement device according to claim 1 .

10. A spectroscopic measurement method using a photodetector having a light receiving section 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, a spectroscopic step of dispersing light to be measured, which is made up of repeatedly occurring optical pulses, to form a spectral image; and a detection step of detecting the spectral image by the photodetector, In the spectroscopic step, the spectral image is formed on the light-receiving surface so that a wavelength axis of the spectral image is parallel to a row direction of the light-receiving surface, In the detecting step, One of K1 and K2 is an integer of 1 or more, and the other is an integer of 2 or more, charge accumulation 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 light to be measured and transfer of the accumulated charge in 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; charge accumulation 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 light to be measured and transfer of the accumulated charges in 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. Spectroscopic measurement method.

11. In the detecting 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. The spectroscopic measurement method according to claim 10.

12. the light under measurement includes first light under measurement and second light under measurement, In the detecting step, a period including a peak of each optical pulse of the first measured light is defined as the first charge accumulation period, and a period including a peak of each optical pulse of the second measured light is defined as the second charge accumulation period. The spectroscopic measurement method according to claim 10.

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