Spectrometry device

Abstract

The spectroscopic measuring device comprises a light entry area, a reflective diffraction grating, an optical detector, a lens, and an evaluation unit. The optical detector outputs initial spectral data of the light to be measured by receiving a spectral image in a first light-receiving area at a first exposure time. It outputs secondary spectral data of the light to be measured by receiving the spectral image in a second light-receiving area, located adjacent to the first, at a second exposure time longer than the first. The evaluation unit generates spectral data based on the first and second spectral data. The optical detector is positioned such that a scattering light region is located within the first light-receiving area, where scattered light accumulates.

Description

Technical area

[0001] The present disclosure relates to a spectroscopic measuring device. Background of the invention

[0002] A spectroscopic measuring device is known that includes a light incident portion that allows the incidence of light to be measured, a reflective diffraction grating that scatters the light to be measured that enters from the light incident portion, an optical detector that detects the light to be measured that is scattered by the reflective diffraction grating, and a lens that guides the light to be measured that enters from the light incident portion to the reflective diffraction grating and forms a spectral image of the light to be measured that is scattered by the reflective diffraction grating in a light receiving area of ​​the optical detector (see, for example, Patent Literature 1). A spectroscopic measuring device that uses such an optical system (referred to as a Dyson optical system) has the advantage of improving the wavelength resolution when measuring the light to be measured.

[0003] On the other hand, the spectroscopic measurement device using the Dyson optical system has the disadvantage of easily generating stray light, and if no measures are taken, the detection accuracy of the light to be measured is likely to decrease. For example, in the spectroscopic measurement device using the Dyson optical system, a stray light region (a region where stray light gathers) is likely to occur due to multiple reflections of part of the light to be measured in the lens. As a countermeasure, therefore, it is conceivable to increase the distance between the light incident region and the optical detector so that the stray light region is not within the light receiving range of the optical detector. List of cited publicationsPatent literature

[0004] Patent Literature 1: Description of US Patent Application Publication No. 2009 / 0237657 Overview of the inventionTechnical problem

[0005] However, as the distance between the light entrance area and the optical detector is increased, the aberration generated by the lens increases, and as a result, there is a possibility that the wavelength resolution in measuring the light to be measured will decrease.

[0006] The object of the disclosure is to provide a spectroscopic measuring device capable of suppressing both a decrease in wavelength resolution and a decrease in detection accuracy when measuring light to be measured. Solution to the problem

[0007] A spectroscopic measuring device of one aspect of the disclosure is [1] “a spectroscopic measuring device comprising a light entrance section allowing the incidence of light to be measured, a reflective diffraction grating configured to scatter the light to be measured entering from the light entrance section, an optical detector configured to detect the light to be measured scattered by the reflective diffraction grating, a lens configured to guide the light to be measured entering from the light entrance section to the reflective diffraction grating and to generate a spectral image of the light to be measured scattered by the reflective diffraction grating on a light receiving area of ​​the optical detector, and an evaluation unit configured to generate spectral data of the light to be measured, wherein the light receiving area comprises a first light receiving area,which includes a plurality of first light detection channels arranged in a direction parallel to a wavelength axis of the spectral image, and a second light receiving region arranged adjacent to the first light receiving region in a direction perpendicular to the wavelength axis and including a plurality of second light detection channels arranged in the direction parallel to the wavelength axis, wherein the optical detector outputs first spectral data of the light to be measured by receiving the spectral image in a first exposure time in the first light receiving region, and outputs second spectral data of the light to be measured by receiving the spectral image in a second exposure time, which is longer than the first exposure time, in the second light receiving region, wherein the evaluation unit generates the spectral data based on the first spectral data and the second spectral data output by the optical detector,and the optical detector is arranged such that a scattered light region in which scattered light generated in an optical path from the light entrance section to the optical detector is collected is arranged in the first light receiving region."

[0008] In the spectroscopic measuring device described in [1], the light receiving section of the optical detector includes the first light receiving section and the second light receiving section, which are arranged side by side in the direction perpendicular to the wavelength axis of the spectral image, and the optical detector is arranged so that the scattered light region, in which the scattered light generated in the optical path from the light entrance section to the optical detector is collected, is located in the first light receiving section. In this way, compared with the case where a distance between the light entrance section and the optical detector is increased so that the scattered light region is not located in the light receiving section of the optical detector, the aberration generated by the lens can be reduced, thereby suppressing a decrease in wavelength resolution when measuring the light to be measured.Furthermore, in the spectroscopic measuring device described in [1], the optical detector outputs the first spectral data of the light to be measured by receiving the spectral image during the first exposure time in the first light receiving region, and outputs the second spectral data of the light to be measured by receiving the spectral image during the second exposure time, which is longer than the first exposure time, in the second light receiving region, and the evaluation unit generates the spectral data of the light to be measured based on the first spectral data and the second spectral data.In this way, by using the first spectral data for a wavelength band where the light intensity is high and the second spectral data for a wavelength band where the light intensity is low, and also shifting the wavelength band corresponding to the scattered light region from a wavelength band where the light intensity is high, when generating the spectral data of the light to be measured, it is possible to suppress a decrease in detection accuracy in the measurement of the light to be measured. As described above, according to the spectroscopic measuring device described in [1], it is possible to suppress both a decrease in wavelength resolution and a decrease in detection accuracy in the measurement of the light to be measured.

[0009] A spectroscopic measuring device of one aspect of the disclosure may be [2] "the spectroscopic measuring device according to [1], wherein the evaluation unit generates the spectral data based on data in a wavelength band that does not include a wavelength band corresponding to the scattered light range in the first spectral data and data in a wavelength band that includes the wavelength band corresponding to the scattered light range in the second spectral data." In the spectroscopic measuring device described in [2], the scattered light in the wavelength band corresponding to the scattered light range in the first spectral data is detected. On the other hand, the scattered light in the wavelength band corresponding to the scattered light range in the second spectral data is not detected.Therefore, according to the spectroscopic measuring apparatus described in [2], a reduction in detection accuracy in measuring the light to be measured can be suppressed by supplementing data in an excluded wavelength band with second spectral data while eliminating an influence of stray light from the first spectral data.

[0010] A spectroscopic measuring device of one aspect of the disclosure may be [3] "the spectroscopic measuring device according to [1] or [2], wherein the optical detector is offset to one side in the direction perpendicular to the wavelength axis with respect to the light entrance portion." According to the spectroscopic measuring device described in [3], an arrangement of the optical detector for positioning the scattered light region in the first light receiving region can be realized simply and reliably.

[0011] A spectroscopic measuring device of one aspect of the disclosure may be [4] "the spectroscopic measuring device according to any one of [1] to [3], wherein the scattered light is generated by multiple reflections of a portion of the light to be measured within the lens." The predominant cause of the occurrence of the scattered light region is multiple reflections of a portion of the light to be measured within the lens. According to the spectroscopic measuring device described in [4], it is possible to further suppress a decrease in detection accuracy in the measurement of the light to be measured by eliminating the influence of the scattered light region.

[0012] A spectroscopic measuring device of one aspect of the disclosure may be [5] "the spectroscopic measuring device according to any one of [1] to [4], further including a mask member disposed between the lens and the optical detector and configured to block the scattered light." According to the spectroscopic measuring device described in [5], it is possible to eliminate the influence of the scattered light region by blocking the incidence of the scattered light on the optical detector. This makes it possible to further suppress the decrease in detection accuracy in the measurement of the light to be measured.

[0013] A spectroscopic measuring device of one aspect of the disclosure may be [6] "the spectroscopic measuring device according to any one of [1] to [5], wherein the lens is a convex lens having a surface facing the light incident portion and the optical detector, and a convex surface facing the reflective diffraction grating." According to the spectroscopic measuring device described in [6], it is possible to direct the light to be measured incident from the light incident portion onto the reflective diffraction grating and form the spectral image of the light to be measured scattered by the reflective diffraction grating in the light receiving area of ​​the optical detector. Advantageous effects of the invention

[0014] According to the disclosure, it is possible to provide a spectroscopic measuring apparatus capable of suppressing both a decrease in wavelength resolution and a decrease in detection accuracy in measuring light to be measured. Brief description of the drawings [ Fig. 1] Fig. 1 is a view showing a structure of a spectroscopic measuring apparatus of an embodiment. [ Fig. 2] Fig. 2 is a view showing a structure of a Fig. 1 shows the optical detector. [ Fig. 3] Fig. 3 is a diagram showing first spectral data and second spectral data. [ Fig. 4] Fig. Figure 4 is a diagram showing the spectral data of the light to be measured. [ Fig. 5] Fig. 5 is a view showing a structure of an optical detector of a first modified example. [ Fig. 6] Fig. 6 is a view showing a structure of an optical detector of a second modified example and the spectral data of the light to be measured. Description of the embodiments

[0015] Hereinafter, embodiments of the disclosure will be described in detail with reference to the drawings. Note that in each drawing, the same or corresponding parts are designated by the same reference numerals, and duplicate descriptions are omitted. [Setup of the spectroscopic measuring device]

[0016] As in Fig. As shown in Figure 1, a spectroscopic measuring device 1 comprises a light entrance section 2, a reflective diffraction grating 3, an optical detector 4, a lens 5, and an evaluation unit 6. The spectroscopic measuring device 1 is a device that generates spectral data of the light L1 to be measured by scattering the light L1 to be measured.

[0017] The light entrance section 2, the reflective diffraction grating 3, and the lens 5 are part of an optical system (so-called Dyson optical system) for guiding the light L1 to be measured to a light receiving area 40 of the optical detector 4 and forming a spectral image α of the light L1 to be measured on the light receiving area 40 of the optical detector 4 along a wavelength axis A. The light L1 to be measured is scattered by the reflective diffraction grating 3 in a direction perpendicular to a direction in which the light L1 to be measured is incident. Here, a direction in which the light L1 to be measured is scattered (ie, a direction parallel to the wavelength axis A) is referred to as an X-axis direction, a direction perpendicular to the X-axis direction is referred to as a Y-axis direction, and a direction perpendicular to both the X-axis direction and the Y-axis direction is referred to as a Z-axis direction.

[0018] The light entrance section 2 is arranged so that the light L1 to be measured is incident on the inside of the spectroscopic measuring device 1. The light entrance section 2 adjusts the incidence of the light L1 to be measured. The light entrance area 2 is, for example, a slit element. Viewed from the Y-axis, a slit formed in the slit element opens in a rectangular shape with a short side in the X-axis direction and a long side in the Z-axis direction. When the width of the short side is increased, the incident intensity of the light L1 to be measured increases, so that spectral data with lower noise and low wavelength resolution are obtained in the evaluation unit 6. On the other hand, when the width of the short side is reduced, the incident intensity of the light L1 to be measured decreases, and thus spectral data with improved wavelength resolution and much noise are obtained in the evaluation unit 6.The light entry section 2 may, for example, comprise a slit element and an optical fiber that transmits the light L1 to be measured to the slit element. Alternatively, the light entry section 2 may, for example, comprise a slit element and a lens that collects the light L1 to be measured from outside the slit element.

[0019] The reflective diffraction grating 3 faces the light entrance portion 2 in the Y-axis direction. The reflective diffraction grating 3 scatters the light L1 to be measured in a direction opposite to the direction in which the light L1 to be measured is incident. The reflective diffraction grating 3 has a plurality of grating grooves (not shown). The plurality of grating grooves extend along the Z-axis direction, which is a direction perpendicular to the alignment direction, while being aligned along the X-axis direction, which is a direction perpendicular to the direction in which the light L1 to be measured is incident. The light L1 to be measured, incident on the reflective diffraction grating 3, is scattered according to the wavelength along the X-axis direction, which is a direction in which the plurality of grating grooves are aligned.

[0020] The optical detector 4 faces the reflective diffraction grating 3 in the Y-axis direction. In the present embodiment, an arrangement position of the optical detector 4 coincides with that of the light entrance section 2 in the Y-axis direction. The optical detector 4 is arranged on the side on which the scattered light L1 to be measured is incident, with a certain distance D between the optical detector 4 and the light entrance section 2 in the Z-axis direction. In other words, the optical detector 4 is offset with respect to the light entrance section 2 toward the side on which the scattered light L1 to be measured is incident in a direction perpendicular to the wavelength axis A (Z-axis direction). The optical detector 4 detects the light L1 to be measured scattered by the reflective diffraction grating 3. In the present embodiment, the optical detector 4 is a CCD image sensor formed on a semiconductor substrate.The CCD image sensor can be an interline type, a frame transfer type, or a full-frame transfer type.

[0021] The lens 5 is arranged in the Y-axis direction between the positions of the light entrance section 2 and the optical detector 4 and the position of the reflective diffraction grating 3. The lens 5 guides the light to be measured L1, which is incident on the reflective diffraction grating 3 from the light entrance section 2, and forms a spectral image α of the light to be measured L1, which is scattered by the reflective diffraction grating 3 in the light receiving area 40 of the optical detector 4. The lens 5 is a convex lens having a surface 5a and a convex surface 5b opposite the surface 5a. The surface 5a faces the light entrance section 2 and the optical detector 4. The surface 5a is a flat surface, a concave surface, or a convex surface. The convex surface 5b faces the reflective diffraction grating 3 and is a convex curved surface opposite the surface 5a.

[0022] The evaluation unit 6 generates spectral data S3 of the light to be measured L1 based on data acquired by the optical detector 4. The content of the analysis by the evaluation unit 6 will be described later. The evaluation unit 6 has a storage unit that stores the data acquired by the optical detector 4, an analysis result, etc. Furthermore, the evaluation unit 6 can control the optical detector 4. The evaluation unit 6 can be, for example, a computer or a tablet terminal equipped with a processor such as a CPU (central processing unit) and a storage medium such as a RAM (random access memory) or a ROM (read-only memory). The evaluation unit 6 can include a microcomputer or an FPGA (field programmable gate array).

[0023] In the spectroscopic measuring device 1 constructed as above, the light to be measured L1, which enters from the light entrance section 2, is incident on the surface 5a at a constant angle of incidence. The light to be measured L1, which is incident on the surface 5a, is refracted at the surface 5a according to the difference between the refractive index of the air and the refractive index of the lens 5, propagates in the lens 5, and exits the convex surface 5b. The light to be measured L1, which exits from the convex surface 5b, is refracted at the convex surface 5b according to the difference between the refractive index of the lens 5 and the refractive index of the air and is guided to the reflective diffraction grating 3 in a subsequent stage.

[0024] The light to be measured, L1, which is scattered by the reflective diffraction grating 3, re-enters the lens 5. In the lens 5, the scattered light, L1, to be measured, strikes the convex surface 5b at a constant angle of incidence. The scattered light, L1, to be measured, which strikes the convex surface 5b, is refracted at the convex surface 5b according to the difference between the refractive index of the air and the refractive index of the lens 5, passes through the interior of the lens 5, and exits the surface 5a. The scattered light, L1, to be measured, emerging from the surface 5a, is refracted at the surface 5a according to the difference between the refractive index of the lens 5 and the refractive index of the air, is imaged in a subsequent stage onto the optical detector 4, and forms a spectral image α on the light receiving area 40.

[0025] Here, scattered light may be generated in an optical path from the light entrance section 2 to the optical detector 4. For example, scattered light L2 may be generated due to multiple reflections of a portion of the light to be measured L1 in the lens 5. For example, a portion of the light to be measured L1 incident from the light entrance section 2 or a portion of the light to be measured L1 scattered by the reflective diffraction grating 3 may be reflected multiple times between the surface 5a and the convex surface 5b and emitted from the surface 5a as scattered light L2. The scattered light L2 may appear as an unnatural peak in the spectral data. With respect to the optical detector 4, if the distance D is increased, the scattered light L2 can be prevented from being incident on the optical detector 4.However, as the distance D increases, the displacement of an imaging position due to a wavelength difference increases, resulting in a decrease in wavelength resolution. In the present embodiment, the distance D is set so that an area where the scattered light L2 accumulates (scattered light area β) is located in a first light receiving area 41 in the light receiving area 40 of the optical detector 4. [Structure of the optical detector]

[0026] As in Fig. 2, the light receiving region 40 of the optical detector 4 is divided into the first light receiving region 41 and a second light receiving region 42. The first light receiving region 41 and the second light receiving region 42 are arranged side by side along the Z-axis direction, which is the direction perpendicular to the wavelength axis A. In the first light receiving region 41, the optical detector 4 has a plurality of first light detection channels 41a arranged side by side along the X-axis direction, which is a direction parallel to the wavelength axis A. Similarly, in the second light receiving region 42, the optical detector 4 has a plurality of second light detection channels 42a arranged side by side along the X-axis direction, which is a direction parallel to the wavelength axis A. The light detection channels 42a and 42b each have a plurality of pixels arranged side by side along the Z-axis direction.Furthermore, the optical detector 4 receives the spectral image α during a first exposure time in the first light receiving area 41, thereby outputting first spectral data S1 of the light to be measured L1 for each of the plurality of first light detection channels 41a. In addition, the optical detector 4 receives the spectral image α during a second exposure time in the second light receiving area 42, thereby outputting second spectral data S2 of the light to be measured L1 for each of the plurality of second light detection channels 42a. The second exposure time is longer than the first exposure time. In the spectral image α formed on the light receiving area 40, the wavelength axis A extends in the X-axis direction, and an image for each wavelength extends in the Z-axis direction. The spectral image α has a vertically symmetrical shape with a boundary between the first light receiving area 41 and the second light receiving area 42 as the axis of symmetry.

[0027] The output of the first spectral data S1 will be described in more detail below. In the first light receiving section 41, charges generated and accumulated in a plurality of pixels included in each of the first light sensing channels 41a are transferred to a first horizontal shift register (not shown). Then, the accumulated charges for each of the first light sensing channels 41a are summed in the first horizontal shift register (hereinafter, this process is referred to as "vertical transfer"). After that, the charges summed in the first horizontal shift register for each of the first light sensing channels 41a are sequentially read from the first horizontal shift register (hereinafter, this process is referred to as "horizontal transfer").Then, a voltage value corresponding to a charge amount read from the first horizontal shift register is output from a first amplifier (not shown), and the voltage value is converted into a digital value by an AD converter. Thus, the first spectral data S1 is output.

[0028] The output of the second spectral data S2 will be described in more detail below. In the second light receiving section 42, charges generated and accumulated in a plurality of pixels included in each of the second light detection channels 42a are transferred to a second horizontal shift register (not shown). Then, the accumulated charges for each of the second light detection channels 42a are summed in the second horizontal shift register (vertical transfer). After that, the charges summed for each of the second light detection channels 42a in the second horizontal shift register are sequentially read from the second horizontal shift register (horizontal transfer). Then, a voltage value corresponding to the amount of charge read from the second horizontal shift register is output from a second amplifier (not shown), and the voltage value is converted into a digital value by the AD converter.In this way, the second spectral data S2 is output.

[0029] In the optical detector 4, the second exposure time in the second light-receiving region 42 is longer than the first exposure time in the first light-receiving region 41. The exposure time of each region can be adjusted, for example, by an electronic shutter. The electronic shutter can be implemented using an anti-blooming gate (ABG).

[0030] The scattered light area β formed by collecting the scattered light L2 is located in the first light receiving area 41. Specifically, the distance D between the light entrance section 2 and the optical detector 4 in the Z-axis direction is set so that the scattered light area β is located in the first light receiving area 41. At this time, the distance D is set so that the scattered light area β is not located in the second light receiving area 42. In other words, the optical detector 4 is arranged so that the scattered light area β in which the scattered light L2 generated in the lens 5 is collected is located in the first light receiving area 41 and not in the second light receiving area 42. In addition, since the scattered light L2 is generated inside the lens 5, a position of the scattered light area β is adjusted by adjusting a positional relationship between the lens 5 and the optical detector 4.Therefore, in the first spectral data S1, the scattered light L2 is detected in a wavelength band Δλ corresponding to the scattered light range β. In an example of . Fig. 2, the scattered light area β is an ellipse with a minor axis along the Z-axis and a major axis along the X-axis, and a length of the minor axis is longer than a length of the first light-receiving area 41 along the Z-axis. Therefore, a part of the scattered light area β is located in the first light-receiving area 41. [Method for generating spectral data of the light to be measured]

[0031] As in Fig. As shown in Figure 3(a), the first spectral data S1 are acquired in the first light receiving area 41 with a short exposure time. The evaluation unit 6 can acquire the light intensity in all wavelength bands without each pixel being saturated in all wavelength bands. In contrast, as shown in Fig. As shown in Figure 3(b), the second spectral data S2 is acquired in the second light receiving area 42 with a long exposure time. The second spectral data S2 includes a wavelength band in which each pixel is saturated. Therefore, the evaluation unit 6 cannot accurately detect the light intensity in the wavelength band in which each pixel is saturated. On the other hand, the first spectral data S1 is superimposed by noise in a wavelength band in which the light intensity is low and has a poor S / N ratio. The second spectral data S2 can provide highly precise data without superimposed noise even in the wavelength band in which the light intensity is low.

[0032] In the first spectral data S1, the scattered light L2 is detected in the wavelength band Δλ corresponding to the scattered light range β. The scattered light L2 is detected as data in the form of a protrusion (bump) in the first spectral data S1. In the first spectral data S1, the wavelength band Δλ corresponding to the scattered light range β is offset from a wavelength band with high light intensity. In other words, the wavelength band Δλ corresponding to the scattered light range β is adjusted so that it does not overlap with the wavelength band in which the light intensity is high. As an adjustment means, for example, the position of the scattered light range β on the first light receiving area 41 is shifted along the wavelength axis A.

[0033] In the first spectral data S1, the evaluation unit 6 sets a threshold value Th1 corresponding to a light intensity greater than the light intensity of the scattered light L2. In the first spectral data S1, the evaluation unit 6 sets a part equal to or greater than the threshold value Th1 as data S11 and sets a part below the threshold value Th1 as data S12. In other words, the data S11 is data in a wavelength band that does not include the wavelength band Δλ corresponding to the scattered light range β in the first spectral data S1. The data S12 is data in a wavelength band that includes the wavelength band Δλ corresponding to the scattered light range β in the first spectral data S1. Therefore, data in which the scattered light L2 is detected is included in the data S12. In addition, data in a wavelength band where the light intensity is low are included in data S12.Further, the evaluation unit 6 sets a threshold value Th2 in the second spectral data S2 whose light intensity is greater than the light intensity of the scattered light L2. In the second spectral data S2, the evaluation unit 6 sets a part equal to or greater than the threshold value Th2 as data S21 and sets a part below the threshold value Th2 as data S22. In other words, the data S21 is data in a wavelength band that does not include the wavelength band Δλ corresponding to the scattered light range β in the second spectral data S2. The data S22 is data in a wavelength band that includes the wavelength band Δλ corresponding to the scattered light range β in the second spectral data S2. Here, the data in the wavelength band in which each pixel is saturated is included in the data S21.Note that in the first spectral data S1, the evaluation unit 6 may set a part that exceeds the threshold value Th1 as data S11 and a part that is equal to or less than the threshold value Th1 as data S12. Furthermore, in the second spectral data S2, a part that exceeds the threshold value Th2 may be set as data S21 and a part that is equal to or less than the threshold value Th2 may be set as data S22.

[0034] As in Fig. 4, the evaluation unit 6 generates third spectral data (spectral data of the light to be measured L1) S3 based on the first spectral data S1 and the second spectral data S2. Specifically, the evaluation unit 6 generates the third spectral data S3 by combining the data S11 and the data S22. The evaluation unit 6 first excludes the data S12 from the first spectral data S1. Then, the evaluation unit 6 cuts out the data S22 from the second spectral data and combines the data S22 with the data S11 to supplement the excluded data S12 with the data S22. The evaluation unit 6 does not use the data S12 including the data in which the scattered light L2 is detected to generate the third spectral data S3, so that the data in which the scattered light L2 is detected is excluded from the third spectral data S3. Furthermore, the evaluation unit 6 does not use the data S21 when generating the third spectral data S3.Therefore, in the third spectral data S3, the pixels are not saturated in all wavelength ranges, and the light intensity can be detected in all wavelength ranges. [Actions and effects]

[0035] In the spectroscopic measuring device 1, the light receiving region 40 of the optical detector 4 includes the first light receiving region 41 and the second light receiving region 42 arranged side by side in the direction perpendicular to the wavelength axis A of the spectral image α, and the optical detector 4 is arranged so that the scattered light region β, in which the scattered light L2 generated in the lens 5 gathers, is located in the first light receiving region 41 and not in the second light receiving region 42. In this way, compared with the case where the distance D between the light entrance section 2 and the optical detector 4 is increased so that the scattered light region β is not located in the light receiving region 40 of the optical detector 4, the aberration generated by the lens 5 can be reduced, thereby suppressing a decrease in the wavelength resolution when measuring the light L1 to be measured.Furthermore, in the spectroscopic measuring device 1, the optical detector 4 outputs the first spectral data S1 of the light to be measured L1 by receiving the spectral image α during the first exposure time in the first light receiving area 41, and outputs the second spectral data S2 of the light to be measured L1 by receiving the spectral image α during the second exposure time, which is longer than the first exposure time, in the second light receiving area 42, and the evaluation unit 6 generates the spectral data S3 of the light to be measured L1 based on the first spectral data S1 and the second spectral data S2.In this way, by using the first spectral data S1 for a wavelength band where the light intensity is high and by using the second spectral data S2 for a wavelength band where the light intensity is low, while, on the other hand, offsetting the wavelength band Δλ corresponding to the scattered light region β from a wavelength band where the light intensity is high when generating the spectral data S3 of the light to be measured L1, it is possible to suppress a decrease in detection accuracy in the measurement of the light to be measured L1. As described above, according to the spectroscopic measuring device 1, it is possible to suppress both a decrease in wavelength resolution and a decrease in detection accuracy in the measurement of the light to be measured L1.

[0036] In the spectroscopic measuring device 1, the evaluation unit 6 generates the spectral data S3 based on the data S11 in the wavelength band that does not include the wavelength band Δλ corresponding to the scattered light range β in the first spectral data S1, and based on the data S22 in the wavelength band that includes the wavelength band Δλ corresponding to the scattered light range β in the second spectral data S2. In the spectroscopic measuring device 1, the scattered light L2 in the wavelength band Δλ corresponding to the scattered light range β in the first spectral data S1 is detected. On the other hand, the scattered light L2 in the wavelength band Δλ corresponding to the scattered light range β in the second spectral data S2 is not detected.Therefore, according to the spectroscopic measuring apparatus 1, a decrease in detection accuracy in the measurement of the light to be measured L1 can be suppressed by supplementing data in an excluded wavelength band using the data S22 in the second spectral data S2 while eliminating an influence of the stray light L2 from the first spectral data S1.

[0037] In the spectroscopic measuring device 1, the optical detector 4 is offset to one side (the side onto which the scattered light L1 to be measured is incident) in the direction perpendicular to the wavelength axis A with respect to the light entrance section 2. In this way, it is possible to simply and reliably realize the arrangement of the optical detector 4 for positioning the scattered light region β in the first light receiving region 41.

[0038] In the spectroscopic measuring device 1, the scattered light L2 is generated, for example, in the lens 5 by multiple reflections of a portion of the light to be measured L1 within the lens 5. The dominant cause of the occurrence of the scattered light region β is multiple reflections of a portion of the light to be measured L1 within the lens 5. In this way, it is possible to further suppress a decrease in detection accuracy in the measurement of the light to be measured L1 by eliminating the influence of the scattered light region β.

[0039] In the spectroscopic measuring device 1, the lens 5 is a convex lens whose surface 5a faces the light entrance section 2 and the optical detector 4, and whose convex surface 5b faces the reflective diffraction grating 3. In this way, it is possible to guide the light L1 to be measured, which is incident from the light entrance section 2 onto the reflective diffraction grating 3, and to generate the spectral image α of the light L1 to be measured, which is scattered by the reflective diffraction grating 3, in the light receiving area 40 of the optical detector 4. [Modified example]

[0040] The disclosure is not limited to the embodiment described above. As in Fig. 5, a mask element 7 may be arranged between the lens 5 and the optical detector 4. In this case, the optical detector 4 is arranged so that the scattered light area β is located in the first light receiving area 41 and not in the second light receiving area 42. However, since the mask element 7 prevents the scattered light L2 from being incident on the first light receiving area 41, the scattered light area β is not directly located in the first light receiving area 41. By disposing the mask element 7, the scattered light L2 is not detected in the first spectral data S1. In this way, it is possible to eliminate the influence of the scattered light L2 by blocking the incidence of the scattered light L2 on the optical detector 4. Therefore, it is possible to further suppress the decrease in detection accuracy when measuring the light L1 to be measured. The mask element 7 is, for example, a light-shielding film.It is sufficient that the size of an outer edge of the mask element 7, viewed from the Y-axis direction, is larger than the size of an outer edge of the scattered light area β. The shape of the mask element 7, viewed from the Y-axis direction, is not limited to a rectangular shape and may be a circular shape, an elliptical shape, or a triangular shape.

[0041] As in Fig. 6, the mask element 7 can be used, in addition to blocking the scattered light L2, also to correct the spectral sensitivity of the optical detector 4. Fig. 6(a) is a view in which a mask element 7a used for correcting the spectral sensitivity is arranged on a light receiving area 40a that is not divided into the first light receiving area 41 and the second light receiving area 42. The mask element 7a is formed based on the characteristics of the spectral data of Fig. 6(b). The Fig. The spectral data shown in Figure 6(b) are data of the light L1 to be measured, which are generated by the evaluation unit 6 when the mask element 7a is not arranged in the light receiving area 40a. The spectral data in Fig. 6(b) is data where the light intensity is high in a middle wavelength band (near 500 nm) of the measured light L1 and low in a low wavelength band (near 200 nm to 300 nm) and a high wavelength band (near 700 nm to 800 nm). The design concept of the mask element 7a is as follows. In the low wavelength band (near 200 nm to 300 nm), the mask element 7a is designed to be arranged in a non-covering manner. An area of ​​the mask element 7a is designed to gradually increase from a wavelength band of 300 nm, and the area of ​​the mask element 7a is designed to be largest in the middle wavelength band (at 500 nm). In addition, the area of ​​the mask element 7a in the high wavelength range (near 700 nm to 800 nm) is designed to gradually decrease from the central wavelength range (near 500 nm).In addition, the mask element 7a is designed to correspond to the position of the scattered light area β.

[0042] Fig. 6(c) are spectral data of the light L1 to be measured, which are generated by the evaluation unit 6 when the mask element 7a is arranged in the light receiving area 40a. The spectral data of Fig. 6(c) show in the low wavelength band (near 200 nm to 300 nm) the same properties as the spectral data of Fig. 6(b). However, in a wavelength band beyond 300 nm, the light intensity becomes a constant value. One reason for this is that the spectral sensitivity is reduced by the mask element 7a in Fig. 6(a). In addition, the mask element 7a masks the incidence of stray light L2 onto the light receiving area 40a. As a result, the stray light L2 is not detected in the spectral data after the sensitivity correction. Therefore, the influence of the stray light L2 can be eliminated by blocking the incidence of the stray light L2 onto the optical detector 4. Note that in Fig. 6(a), the mask element 7a is divided into two parts. However, as long as the above-mentioned design concept is followed, the mask element 7a may have a one-piece shape or be divided into three or more parts.

[0043] The optical detector 4 may be a CMOS image sensor. In the case of a CMOS image sensor, each pixel has a photodiode (photoelectric conversion element) and an amplifier. The photodiode accumulates electrons (photoelectrons) generated as charges by the incident photons. The amplifier converts the charges accumulated in the photodiode into voltages and amplifies the converted voltages. The amplified voltages are transmitted to the AD converter for each of the first light detection channels 41a and each of the second light detection channels 42a by switching a selector switch of each pixel. The amplified voltages are converted into digital values ​​by the AD converter and output as the first spectral data S1 and the second spectral data S2.

[0044] The optical detector 4 may be a CCD-CMOS image sensor. In the case of the CCD-CMOS image sensor, the optical detector 4 has a plurality of signal extraction circuits corresponding to each of the first light detection channels 41a and each of the second light detection channels 42a. Each of the signal extraction circuits has a transistor and a signal output pad. A voltage corresponding to the amount of charge transferred by each of the first light detection channels 41a and each of the second light detection channels 42a is applied to a control terminal of the transistor. Then, a current whose magnitude corresponds to the corresponding voltage level is output from the output terminal of the transistor and discharged via the signal output pad. The extracted current is converted into a digital value by the AD converter and output as the first spectral data S1 and the second spectral data S2.

[0045] The scattered light L2 does not necessarily have to be generated in the lens 5, but can also be generated in an optical path extending from the light entrance section 2 to the optical detector 4. For example, the scattered light L2 can be generated between the light entrance section 2 and the lens 5, between the lens 5 and the reflective diffraction grating 3, or between the lens 5 and the optical detector 4. List of reference symbols

[0046] 1: spectroscopic measuring device, 2: light entrance area, 3: reflective diffraction grating, 4: optical detector, 5: lens, 5a: surface, 5b: convex surface, 6: evaluation unit, 7, 7a: mask element, 40: light receiving area, 41: first light receiving area, 41a: first light detection channel, 42: second light receiving area, 42a: second light detection channel, A: wavelength axis, L1: light to be measured, L2: scattered light, S1: first spectral data, S2: second spectral data, S3: spectral data, α: spectral image, β: scattered light area.

Claims

[1] A spectroscopic measuring device, with: a light entry section designed for the entry of light to be measured; a reflective diffraction grating configured to scatter the light to be measured incident from the light entrance portion; an optical detector configured to detect the light to be measured scattered by the reflective diffraction grating; a lens configured to guide the light to be measured incident from the light entrance portion to the reflective diffraction grating and to generate a spectral image of the light to be measured scattered by the reflective diffraction grating on a light receiving area of the optical detector; and an evaluation unit designed to generate spectral data of the light to be measured, wherein: the light reception area has: a first light receiving region having a plurality of first light detection channels arranged in a direction parallel to a wavelength axis of the spectral image; and a second light receiving region arranged adjacent to the first light receiving region in a direction perpendicular to the wavelength axis and including a plurality of second light detecting channels arranged in the direction parallel to the wavelength axis, the optical detector outputs first spectral data of the light to be measured by receiving the spectral image during a first exposure time in the first light receiving area, and outputs second spectral data of the light to be measured by receiving the spectral image during a second exposure time, which is longer than the first exposure time, in the second light receiving area, the evaluation unit generates the spectral data based on the first spectral data and the second spectral data output by the optical detector, and the optical detector is arranged such that a scattered light region is located in the first light receiving region, in which scattered light is collected that is generated in an optical path running from the light entry section to the optical detector. [2] The spectroscopic measuring device according to claim 1, wherein the evaluation unit generates the spectral data based on data in a wavelength band that does not include a wavelength band corresponding to the scattered light region in the first spectral data and on the basis of data in a wavelength band that includes the wavelength band corresponding to the scattered light region in the second spectral data. [3] The spectroscopic measuring device according to claim 1 or 2, wherein the optical detector is offset to one side in a direction perpendicular to the wavelength axis with respect to the light entrance region. [4] The spectroscopic measuring device according to claim 1 or 2, wherein the scattered light is generated by multiple reflections of a part of the light to be measured within the lens. [5] The spectroscopic measuring device according to claim 1 or 2, further comprising a mask member disposed between the lens and the optical detector and configured to block the scattered light. [6] The spectroscopic measuring device according to claim 1 or 2, wherein the lens is a convex lens having a surface facing the light entrance portion and the optical detector and a convex surface facing the reflective diffraction grating.

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