Spectroscopic measuring device and spectroscopic measuring 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 apparatus and a spectroscopic measurement method.

Background Art

[0002] Spectroscopic measurement technology can receive the spectroscopic image of the measurement light generated in the object by a photodetector and obtain the spectrum of the measurement light, and analyze the composition of the object or monitor the phenomenon 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 at this time, the object can be analyzed based on the fluorescence spectrum.

[0003] The photodetector used at this time 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 two-dimensionally arranged. The spectroscopic image is formed on the light receiving surface such that its wavelength axis is parallel to the row direction of the light receiving surface. Each pixel of the light receiving surface generates electric charges in response to light incidence and accumulates the electric charges. The electric charges accumulated by each pixel are integrated for each column, and an electric signal corresponding to the amount of electric charge integration for each column is output as spectral data.

[0004] In such spectroscopic measurement technology, if the object is repeatedly irradiated with excitation light pulses to repeatedly generate fluorescence pulses in the object, and the spectra of the fluorescence pulses can be obtained under various conditions (for example, conditions such as the start and end times of charge accumulation with respect to the light pulse waveform), it is expected that the object can be analyzed in more detail based on those spectra.

[0005] The photodetector described in Patent Document 1 has a light receiving surface on which a spectroscopic image of the measurement light is formed, which is divided into a first region and a second region, and spectra can be obtained by each of the first region and the second region. By using such a photodetector, it is expected that two types of spectra can be obtained for the common measurement light.

Prior Art Documents

[0006] [Patent Document 1] Japanese Patent Publication No. 2018-174324 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] In the case of light to be measured consisting of repeatedly occurring light pulses, as in the fluorescence example above, if the period of repeated generation of light pulses is short, it is difficult to efficiently acquire the spectrum of the light to be measured under various exposure conditions. Generally, photodetectors used in spectroscopic measurements have a large number of pixel array columns, and the time required to output an electrical signal corresponding to the charge accumulation amount for each column is long. During the period in which this electrical signal is output, even if a pixel that receives a light pulse generates a charge, that charge must be discharged without being accumulated. To address this problem, it is conceivable to use a photodetector designed to operate with a high-speed clock, but the realization of such a photodetector is difficult in terms of device design and noise design.

[0008] The present invention was made to solve the above-mentioned problems, and aims to provide a spectroscopic measuring device and spectroscopic measuring method that can efficiently acquire the spectrum of a light to be measured, consisting of rapidly occurring light pulses, under various exposure conditions with a simple configuration. [Means for solving the problem]

[0009] A first aspect of the spectroscopic measuring device of the present invention comprises an optical system that spectrally analyzes light to be measured, consisting of repeatedly occurring light 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 light-receiving unit in which a plurality of pixels that each generate a charge in response to incident light are arranged in a two-dimensional array of (M1+M2) rows and N columns (where M1, M2, and N are integers 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, and a spectral image is formed on the light-receiving surface such that the wavelength axis of the spectral image is parallel to the row direction of the light-receiving surface; (2) a first output unit that integrates the charge generated and accumulated by each pixel in the first region during a first charge accumulation period for each column and outputs a first electrical signal corresponding to the amount of charge accumulated for each column; and (3) a second output unit that integrates the charge generated and accumulated by each pixel in the second region during a second charge accumulation period for each column and outputs a second electrical signal corresponding to the amount of charge accumulated for each column. The control unit sets either K1 or K2 to an integer of 1 or more and the other to an integer of 2 or more, and (1) causes the unit to perform charge accumulation in each pixel of the first region over a first charge accumulation period and transfer the charge accumulated by each pixel of the first region to the first output unit K1 times in synchronization with the generation timing of each optical pulse of the light being measured, and thereafter outputs a first electrical signal from the first output unit corresponding to the charge accumulation amount for each row over K1 times, and (2) causes the unit to perform charge accumulation in each pixel of the second region over a second charge accumulation period and transfer the charge accumulated by each pixel of the second region to the second output unit K2 times in synchronization with the generation timing of each optical pulse of the light being measured, and thereafter outputs a second electrical signal from the second output unit corresponding to the charge accumulation amount for each row over K2 times.

[0010] In a second aspect of the spectroscopic measuring device of the present invention, in addition to the first aspect, the control unit independently performs charge accumulation and charge transfer in the first region and output of a first electrical signal from the first output unit, and charge accumulation and charge transfer in the second region and output of a second electrical signal from the second output unit.

[0011] In a third aspect of the spectroscopic measuring 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 measuring device of the present invention, in addition to any of the first to third aspects, the control unit defines the period including the peak of each light pulse of the light being measured as the first charge accumulation period, and the period not including the peak of each light pulse of the light being measured as the second charge accumulation period.

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

[0014] In the sixth aspect of the spectroscopic measuring 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 the seventh aspect of the spectroscopic measuring apparatus of the present invention, in addition to any of the first to third aspects, the light to be measured includes a first light to be measured and a second light to be measured, and the control unit sets the period including the peak of each light pulse of the first light to be measured as the first charge accumulation period, and the period including the peak of each light pulse of the second light to be measured as the second charge accumulation period.

[0016] In the eighth aspect of the spectroscopic measuring 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 to accumulate or discharge the charge generated by each pixel, and the control unit uses the electronic shutter function of the photodetector to set a first charge accumulation period and a second charge accumulation period.

[0017] In the ninth aspect of the spectroscopic measuring device of the present invention, in addition to any of the first to eighth aspects, the photodetector has an electronic shutter function that selects either to accumulate or discharge the charge generated by each pixel, and the control unit uses the electronic shutter function of the photodetector to transfer the charge accumulated by each pixel for a portion of the first region to the first output unit and then discharge the charge from all pixels in the first region, and transfers the charge accumulated by each pixel for a portion of the second region to the second output unit and then discharges 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 arranged in a two-dimensional array of (M1 + M2) rows and N columns (where M1, M2, and N are integers of 2 or more) on the 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 comprises a spectral step of spectrally analyzing the light to be measured, which consists of repeatedly occurring light pulses, to form a spectral image, and a detection step of detecting the spectral image with a photodetector. In the spectral step, the spectral image is formed on the light-receiving surface such 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 set to an integer of 1 or more and the other to an integer of 2 or more, and (1) charge accumulation and transfer of the accumulated charge of each pixel in the first region are performed K1 times over a first charge accumulation period, synchronized with the generation timing of each light pulse of the light being measured, and thereafter a first electrical signal is output corresponding to the amount of charge accumulated for each column over K1 times, and (2) charge accumulation and transfer of the accumulated charge of each pixel in the second region are performed K2 times over a second charge accumulation period, synchronized with the generation timing of each light pulse of the light being measured, and thereafter a second electrical signal is output corresponding to the amount of charge accumulated for each column over K2 times.

[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 the output of a first electrical signal are performed independently of each other, as are charge accumulation and charge transfer in the second region and the output of a second electrical signal.

[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 of the first to third aspects, in the detection step, the period including the peak of each light pulse of the light to be measured is defined as the first charge accumulation period, and the period not including the peak of each light pulse of the light to be measured is defined as the second charge accumulation period.

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

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

[0024] In the 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, the period including the peak of each light pulse of the light to be measured is set as the first charge accumulation period, and the period not including the peak of each light pulse of the light to be measured is set as the second charge accumulation period.

[0025] In the 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, as the photodetector, one having an electronic shutter function for selecting either the accumulation or discharge of the charges generated by each pixel is used, and the first charge accumulation period and the second charge accumulation period are set by utilizing the electronic shutter function of the photodetector.

[0026] In the ninth aspect of the spectroscopic measurement method of the present invention, in addition to any one of the first to eighth aspects, in the detection step, as the photodetector, one having an electronic shutter function for selecting either the accumulation or discharge of the charges generated by each pixel is used, and by utilizing the electronic shutter function of the photodetector, after transferring the charges accumulated by each pixel for some rows in the first region to the first output unit, the charges of all pixels in the first region are discharged, and after transferring the charges accumulated by each pixel for some rows in the second region to the second output unit, the charges of all pixels in the second region are discharged.

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

Advantages of the Invention

[0028] According to the present invention, the spectrum of the light to be measured composed of light pulses that occur repeatedly at high speed can be efficiently acquired under various exposure conditions with a simple configuration. [Brief explanation of the drawing]

[0029] [Figure 1] Figure 1 shows the configuration of the spectroscopic measurement device 1. [Figure 2] Figure 2 shows the configuration of the photodetector 20. [Figure 3] Figure 3 shows the configuration of the light-receiving section 21 of the photodetector 20. [Figure 4] Figure 4 is a timing chart illustrating an example of setting the charge accumulation period using the electronic shutter function. [Figure 5] Figure 5 is a timing chart illustrating an example of control of the operation of the photodetector 20 by the control unit 30. [Figure 6] Figures 6(a) and 6(b) are timing charts illustrating other examples of control of the operation of the photodetector 20 by the control unit 30. [Figure 7] Figure 7 is a timing chart illustrating other examples of setting the charge accumulation period using the electronic shutter function. [Modes for carrying out the invention]

[0030] Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the attached drawings. In the description of the drawings, the same elements will be denoted by the same reference numerals, and redundant descriptions will be omitted. The present invention is not limited to these examples, but is indicated by the claims, and all modifications within the meaning and scope equivalent to the claims are intended to be included.

[0031] Figure 1 shows the configuration of the spectroscopic measurement device 1. The spectroscopic measurement device 1 comprises an optical system 10, a photodetector 20, and a control unit 30, and acquires the spectrum of the light to be measured that reaches the object S. The light to be measured consists of repeatedly occurring light pulses. For example, the light to be measured consists of fluorescence 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 the light. The optical system 10 spectrally separates the light to be measured into its wavelength components using a spectroscopic element such as a grating or 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 Czerni-Turner spectrometer or a Dyson spectrometer.

[0033] The photodetector 20 has a light-receiving surface on which multiple pixels, each generating an electric charge in response to incident light, are arranged in a two-dimensional array. The spectral image is formed on the light-receiving surface such 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. Preferably, the photodetector 20 is made thinner by grinding the back surface of the semiconductor substrate (the surface opposite to the image sensor formation surface) and is capable of high-sensitivity light detection in a high wavelength band. Furthermore, a CCD image sensor is preferred because it is more sensitive 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 this light pulse generation. For example, the control unit 30 repeatedly generates fluorescence pulses by repeatedly irradiating the object S with excitation light pulses in synchronization with a trigger signal, 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 this light pulse generation. For example, the external control unit 40 repeatedly generates fluorescence pulses by repeatedly irradiating the object S with excitation light pulses in synchronization with the trigger signal, and also provides the same trigger signal to the control unit 30.

[0036] Figure 2 shows the configuration of the photodetector 20. The photodetector 20 comprises a light receiving unit 21, a first output unit 23A, and a second output unit 23B. Figure 3 shows the configuration of the light receiving unit 21 of the photodetector 20.

[0037] 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 arranged in a two-dimensional array of (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 all integers greater than or equal to 2. 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 the charge it generates in response to incident light over a first charge accumulation period, and then sequentially transfers the accumulated charge to the first output unit 23A along the column direction (charge transfer direction A1) for each column. The first output unit 23A integrates the charge generated and accumulated by each pixel in the first region 21A during the first charge accumulation period for each column, and outputs a first electrical signal as first spectral data corresponding to the accumulated charge for each column.

[0039] In the second region 21B, each pixel accumulates the charge it generates in response to incident light over the second charge accumulation period, and sequentially transfers the accumulated charge to the second output unit 23B along the column direction (charge transfer direction A2) for each column. The second output unit 23B integrates the charge 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 as second spectral data corresponding to the accumulated charge for each column.

[0040] The first output unit 23A and the second output unit 23B may each be configured to include a shift register that sequentially shifts and outputs the charge accumulated for each column, and an amplifier that takes the charge sequentially output from the shift register as input and outputs a voltage value corresponding to the amount of charge. Alternatively, the first output unit 23A and the second output unit 23B may each be configured to include an amplifier that converts the charge accumulated 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 the optical pulse generation of the light being measured. The control unit 30 controls the operation of charge accumulation in each pixel in the first region 21A, the 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 the output of the first electrical signal from the first output unit 23A (hereinafter referred to as "first horizontal transfer"). The control unit 30 also controls the operation of charge accumulation in each pixel in the second region 21B, the transfer of the charge 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 the second electrical signal from the second output unit 23B (hereinafter referred to as "second horizontal transfer"). The control unit 30 causes charge accumulation, first vertical transfer, and first horizontal transfer in the first region 21A and 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, based on a trigger signal synchronized with the generation timing of each optical pulse of the light being measured, causes each pixel in the first region 21A to perform charge accumulation and a first vertical transfer K1 times over a first charge accumulation period, and then causes a first horizontal transfer. The control unit 30 also causes each pixel in the second region 21B to perform charge accumulation and a second vertical transfer K2 times over a second charge accumulation period, synchronized with the generation timing of each optical pulse of the light being measured, and then causes a second horizontal transfer. Of K1 and K2, one is an integer of 1 or more, and the other is an integer of 2 or more.

[0043] The spectral measurement method of this embodiment comprises a spectral step of forming a spectral image by spectrally analyzing the light to be measured, which consists of repeatedly occurring light pulses, using an optical system 10, and a detection step of detecting the spectral image with a photodetector 20. In the detection step, the photodetector 20 is made to perform operations based on the control by the control unit 30 described above.

[0044] The photodetector 20 preferably has an electronic shutter function that allows it to select either to store or discharge the charge generated by each pixel. In this case, the control unit 30 can use the electronic shutter function of the photodetector 20 to set a first charge storage period and a second charge storage period. The first charge storage period and the second charge storage period may be the same length or may be different lengths.

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

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

[0047] In the first region 21A, during the period containing the peak of the fluorescence pulse (first charge accumulation period), the electron shutter is open, and the charge generated by the pixel is accumulated. In the second region 21B, during the period at the tail of the fluorescence pulse after the peak (second charge accumulation period), the electron shutter is open, and the charge generated by the pixel is accumulated. The first and second charge accumulation periods each begin at a time delayed by a certain amount of time from the rising edge timing of the trigger signal, and end at a time delayed by a certain amount of time from that time. During the period when the electron shutter is closed, even if a pixel generates charge, that charge is discharged without being accumulated.

[0048] Thus, the start times of the first charge accumulation period and the second charge accumulation period may be different from each other, and their end times may also be different. The first charge accumulation period and the second charge accumulation period may overlap in some parts, or they may not overlap. Furthermore, the first charge accumulation period may be the period that includes the peak of the fluorescence pulse, while the second charge accumulation period may be the period that does not include the peak of the fluorescence pulse.

[0049] Figure 5 is a timing chart illustrating an example of control of the operation of the photodetector 20 by the control unit 30. From top to bottom, the figure shows the trigger signal waveform, fluorescence pulse waveform, electron shutter operation of the first region 21A (accumulation / discharge of charge in the pixels), transfer of the charge accumulated by each pixel in the first region 21A to the first output unit 23A (first vertical transfer), output of the first electrical signal from the first output unit 23A (first horizontal transfer), electron shutter operation of the second region 21B (accumulation / discharge of charge in the pixels), transfer of the charge accumulated by each pixel in the second region 21B to the second output unit 23B (second vertical transfer), and output of the second electrical signal from the second output unit 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 fluorescence pulse is generated from this point onward. The fluorescence 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 the electronic shutter function to begin at a time after a delay time (first delay time) D1 has elapsed from the rising edge timing of the trigger signal, and to a period of length T1. The transfer of the charge accumulated by each pixel in the first region 21A to the first output unit 23A (first vertical transfer) takes place during the period from the middle of the first charge accumulation period until the end of the first charge accumulation period. The output of the first electrical signal from the first output unit 23A (first horizontal transfer) takes place after the charge accumulation of each pixel in the first region 21A and the first vertical transfer have been performed K1 times over the first charge accumulation period.

[0052] In the second region 21B, the second charge accumulation period is set by the electronic shutter function to begin at a time after a delay time (second delay time) D2 has elapsed from the rising edge timing of the trigger signal, and to a period of length T2. The transfer of the charge accumulated by each pixel in the second region 21B to the second output unit 23B (second vertical transfer) takes place during the period from the middle of the second charge accumulation period until the end of the second charge accumulation period. The output of the second electrical signal from the second output unit 23B (second horizontal transfer) takes place after the charge accumulation of each pixel in the second region 21B and the first vertical transfer have been performed K2 times over the second charge accumulation period.

[0053] In the example shown in this figure, the first charge accumulation period is a period in which the fluorescence intensity is relatively high and includes the peak of the fluorescence pulse, while the second charge accumulation period is a period in which the fluorescence intensity is relatively low and does not include the peak of the fluorescence pulse. In this case, it is preferable to set K2 to be greater than K1. Alternatively, it is also preferable to set the time T2 of the second charge accumulation period to be longer than the time T1 of the first charge accumulation period.

[0054] As shown in this figure, in the case of light under measurement consisting of repeatedly occurring light pulses, if the period of repeated generation of light pulses is short (if the period of the trigger signal is short), light pulses may occur during the first horizontal transfer period when the first output unit 23A is outputting the first electrical signal, and light pulses may also occur during the second horizontal transfer period when the second output unit 23B is outputting the second electrical signal. During the first horizontal transfer period when the first output unit 23A is outputting the first electrical signal, even if a pixel in the first region 21A receives a light pulse and generates a charge, that charge must be discharged without being accumulated. Similarly, during the second horizontal transfer period when the second output unit 23B is outputting the second electrical signal, even if a pixel in the second region 21B receives a light pulse and generates a charge, that charge must be discharged without being accumulated. This situation arises because photodetectors commonly used in spectroscopic measurements have a large number of pixel arrays (N), resulting in a long time required to output an electrical signal corresponding to the charge accumulation in each row (horizontal transmission time). Consequently, efficiently acquiring the spectrum of the light being measured is difficult.

[0055] To address these issues, this embodiment utilizes the fact that the number of rows M1 and M2 in the pixel array is relatively small, resulting in a relatively short time required for vertical transfer. In the first region 21A, charge accumulation and the first vertical transfer are performed multiple times for each pixel, followed by the first horizontal transfer in the first output unit 23A. In the second region 21B, charge accumulation and the second vertical transfer are performed multiple times for each pixel, followed by the second horizontal transfer in the second output unit 23B. By doing so, the frequency at which pixels are forced to discharge the charge generated by receiving a light pulse without accumulating it can be reduced, thereby enabling efficient acquisition of the spectrum of the light being measured.

[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. As a result, compared to the case where two sets of optical systems and photodetectors are used to acquire two spectra, in this embodiment, optical errors are small, and the effects of optical distortion and temperature drift are easily corrected. In addition, in this embodiment, it is easy to synchronize the operations for acquiring the two spectra, the system construction is simple, and the effects of timing errors due to jitter, etc. are small. Furthermore, this embodiment is also advantageous in terms of miniaturization and cost reduction.

[0057] Figures 6(a) and 6(b) are timing charts illustrating other control examples 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 fluorescence pulse waveform, the electronic shutter operation of the first region 21A (accumulation / discharge of pixel charge), the transfer of the charge accumulated by each pixel in 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). In the operation examples shown in these figures, the charge accumulated by each pixel in some rows of the M1 row N column pixel array of the first region 21A that are close to the first output unit 23A is sequentially transferred to the first output unit 23A (first vertical transfer), and then the charge of all pixels in the first region 21A is discharged by the electronic shutter function.

[0058] Figure 6(a) shows the case where the trigger signal period is relatively short and the number of rows for vertical charge transfer is relatively small. Figure 6(b) shows the case where the trigger signal period is relatively long and the number of rows for vertical charge transfer is relatively large. As shown in these figures, it is preferable to set the number of rows for vertical charge transfer according to the trigger signal period, 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. That is, when the trigger signal period is short, the number of rows for vertical charge transfer is reduced, the time T1 of the first charge accumulation period is shortened, the time for vertical transfer is shortened, and K1 is increased. In this way, by setting the number of rows for vertical charge transfer according to the period of repeated generation of optical pulses (according to the trigger signal period), the spectrum of the light under measurement can be acquired more efficiently.

[0059] Figure 7 is a timing chart illustrating other setting examples for the charge accumulation period using the electronic shutter function. From top to bottom, the figure shows the first trigger signal waveform, the first fluorescence pulse waveform, the second trigger signal waveform, the second fluorescence pulse waveform, the accumulation / discharge of pixel charge in the first region 21A, the electronic shutter operation in the first region 21A, the accumulation / discharge of pixel charge in the second region 21B, and the 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 fluorescence pulse is generated from this point onward. Similarly, the second excitation light pulse is irradiated onto the object S at the rising edge of the second trigger signal, and the second fluorescence pulse is generated from this point onward. The fluorescence intensity of the first and second fluorescence pulses gradually increases from the rising edge of the trigger signal, reaches a peak, and then gradually decreases.

[0061] In the example shown in this figure, the external control unit 40 outputs a first trigger signal and a second trigger signal to the control unit 30, respectively. The control unit 30 controls the operation of such a photodetector 20 based on the first trigger signal and the second trigger signal, which are synchronized with the timing of the optical pulse generation of the first light under measurement and the second light under measurement, respectively.

[0062] In the first region 21A, during the period including the peak of the first fluorescence pulse (first charge accumulation period), the electron shutter is open, and the charge generated by the pixel is accumulated. In the second region 21B, during the period including the peak of the second fluorescence pulse (second charge accumulation period), the electron shutter is open, and the charge generated by the pixel is accumulated. The first and second charge accumulation periods each begin at a time delayed by a certain period from the rising edge timing of the trigger signal, and end at a time delayed by a certain period from that time. During the period when the electron shutter is closed, even if a pixel generates charge, that charge is discharged without being accumulated.

[0063] Thus, the start times of the first charge accumulation period and the second charge accumulation period may be different from each other, and their end times may also be different. The first charge accumulation period and the second charge accumulation period may or may not overlap in some parts. Furthermore, the first charge accumulation period may include the peak of the second fluorescence pulse, and the second charge accumulation period may include the peak of the first fluorescence pulse.

[0064] In the above description of the embodiments, fluorescence pulses repeatedly generated in an object by repeatedly irradiating the object with excitation light pulses were given as an example of repeatedly generated light pulses. However, the light pulses to be measured by the spectroscopic measuring device and spectroscopic measuring method of this embodiment are not limited to this. For example, the spectroscopic measuring device and spectroscopic measuring method of this embodiment can also be used to measure the spectrum of light pulses that repeatedly occur in synchronization with pulsed plasma in a process of dry etching an object by a plasma process. [Explanation of symbols]

[0065] 1...Spectroscopic measuring device, 10...Optical system, 20...Photodetector, 21...Light receiving unit, 21A...First region, 21B...Second region, 22...Pixel, 23A...First output unit, 23B...Second output unit, 30...Control unit.

Claims

1. The system comprises an optical system that spectrally analyzes light to be measured, consisting of repeatedly occurring light 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 aforementioned photodetector is A light-receiving unit is provided in which multiple pixels, each generating an electric charge in response to incident light, are arranged in a two-dimensional array of (M1 + M2) rows and N columns (where M1, M2, and N are integers of 2 or more) on a light-receiving surface, 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, and the spectral image is formed on the light-receiving surface such that the wavelength axis of the spectral image is parallel to the row direction of the light-receiving surface, A first output unit that accumulates the charge generated and accumulated by each pixel in the first region during the first charge accumulation period, for each row, and outputs a first electrical signal corresponding to the accumulated charge amount for each row, A second output unit that accumulates the charge generated and accumulated by each pixel in the second region during the second charge accumulation period, for each row, and outputs a second electrical signal corresponding to the accumulated charge for each row, Includes, The control unit, Let K1 and K2 be integers of 1 or greater, and the other be integers of 2 or greater. In synchronization with the generation timing of each optical pulse of the light being measured, charge accumulation in each pixel of the first region over the first charge accumulation period and the 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 accumulation amount for each column over K1 times is output from the first output unit. In synchronization with the generation timing of each optical pulse of the light being measured, charge accumulation in each pixel of the second region and the transfer of the charge accumulated by each pixel of the second region to the second output unit are performed K2 times over the second charge accumulation period, and thereafter, the second electrical signal corresponding to the charge accumulation amount for each column over K2 times is output from the second output unit, 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 to occur independently of each other, and charge accumulation and charge transfer in the second region and output of the second electrical signal from the second output unit. Spectrometer.

2. The control unit makes the first charge accumulation period and the second charge accumulation period different from each other. The spectroscopic measuring apparatus according to claim 1.

3. The control unit defines the period including the peak of each light pulse of the light being measured as the first charge accumulation period, and the period not including the peak of each light pulse of the light being measured as the second charge accumulation period. The spectroscopic measuring apparatus according to claim 1.

4. The control unit sets K2 to be greater than K1. The spectroscopic measuring apparatus according to claim 3.

5. The control unit sets the second charge accumulation period to be longer than the first charge accumulation period. The spectroscopic measuring apparatus according to claim 3.

6. The light to be measured includes a first light to be measured and a second light to be measured. The control unit defines the period including the peak of each light pulse of the first light to be measured as the first charge accumulation period, and the period including the peak of each light pulse of the second light to be measured as the second charge accumulation period. The spectroscopic measuring apparatus according to claim 1.

7. The photodetector has an electronic shutter function that selects either to accumulate or discharge the charge generated by each pixel. The control unit sets the first charge accumulation period and the second charge accumulation period using the electronic shutter function of the photodetector. The spectroscopic measuring apparatus according to claim 1.

8. The photodetector has an electronic shutter function that selects either to accumulate or discharge the charge generated by each pixel. The control unit utilizes the electronic shutter function of the photodetector to transfer the charge accumulated by each pixel in a portion of the first region to the first output unit, and then discharges the charge from all pixels in the first region; and transfers the charge accumulated by each pixel in a portion of the second region to the second output unit, and then discharges the charge from all pixels in the second region. The spectroscopic measuring apparatus according to claim 1.

9. In a spectroscopic measurement method using a photodetector having a light-receiving section in which multiple pixels, each generating an electric charge in response to incident light, are arranged in a two-dimensional array of (M1 + M2) rows and N columns (where M1, M2, and N are integers 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 system comprises a spectral step of spectrally analyzing the light to be measured, which consists of repeatedly occurring light pulses, to form a spectral image, and a detection step of detecting the spectral image with the photodetector. In the spectral step, the spectral image is formed on the light-receiving surface such that the wavelength axis of the spectral image is parallel to the row direction of the light-receiving surface. In the detection step, Let K1 and K2 be integers of 1 or greater, and the other be integers of 2 or greater. In synchronization with the generation timing of each optical pulse of the light being measured, charge accumulation in each pixel of the first region and the transfer of the charge accumulated by each pixel of the first region are performed K1 times over a first charge accumulation period, and thereafter, a first electrical signal corresponding to the charge accumulation amount for each column over K1 times is output. In synchronization with the generation timing of each optical pulse of the light being measured, charge accumulation in each pixel of the second region and the transfer of the charge accumulated by each pixel of the second region are performed K2 times over a second charge accumulation period, and thereafter, a second electrical signal corresponding to the charge accumulation amount for each column over K2 times is output, In the detection step, charge accumulation and charge transfer in the first region and the output of the first electrical signal are performed independently of each other, Spectroscopic measurement method.

10. In the detection step, the period including the peak of each light pulse of the light being measured is defined as the first charge accumulation period, and the period not including the peak of each light pulse of the light being measured is defined as the second charge accumulation period. The spectroscopic measurement method according to claim 9.

11. The light to be measured includes a first light to be measured and a second light to be measured. In the detection step, the period including the peak of each light pulse of the first light to be measured is defined as the first charge accumulation period, and the period including the peak of each light pulse of the second light to be measured is defined as the second charge accumulation period. The spectroscopic measurement method according to claim 9.

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