Spectroscopic measurement device

Abstract

This spectroscopic measurement device is provided with a light incidence unit, a reflective diffraction grating, a light detector, a lens, and an analysis unit. And a light detector that outputs first spectral data of the light to be measured by receiving the spectroscopic image for a first exposure time in a first light receiving region, and outputs second spectral data of the light to be measured by receiving the spectroscopic image for a second exposure time longer than the first exposure time in a second light receiving region provided parallel to the first light receiving region. And an analysis unit that generates spectral data on the basis of the first spectral data and the second spectral data. The light detector is disposed such that a stray light region where stray light is concentrated is located in the first light receiving region.

Description

Technical Field

[0001] The present disclosure relates to a spectrophotometric device. Background Art

[0002] A spectrophotometric device is known, which includes: a light incident portion that allows light to be measured to be incident; a reflective diffraction grating that separates the light to be measured incident from the light incident portion; a photodetector that detects the light to be measured separated by the reflective diffraction grating; and a lens that guides the light to be measured incident from the light incident portion to the reflective diffraction grating and forms a spectroscopic image of the light to be measured separated by the reflective diffraction grating on a light receiving area of ​​the photodetector (for example, refer to Patent Document 1). In a spectrophotometric device that adopts this optical system (called a Dyson optical system), there is an advantage that the wavelength resolution in the measurement of the light to be measured is improved.

[0003] On the other hand, in the spectrophotometric device using the Dyson optical system, there is a disadvantage that stray light is easily generated. If no countermeasures are implemented, the detection accuracy in the measurement of the measured light is easily reduced. For example, in the spectrophotometric device using the Dyson optical system, a stray light area (an area where stray light is concentrated) is easily generated due to multiple reflections of a part of the measured light in the lens. As a countermeasure to achieve this purpose, it is considered to increase the distance between the light incident part and the light detector in such a way that the stray light area is not located in the light receiving area of ​​the light detector.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: U.S. Patent Application Publication No. 2009 / 0237657 Summary of the invention

[0007] Problem that the invention aims to solve

[0008] However, if the distance between the light incident portion and the photodetector is increased, the aberration caused by the lens becomes larger, and as a result, there is a possibility that the wavelength resolution in the measurement of the light to be measured will be reduced.

[0009] An object of the present disclosure is to provide a spectroscopic measurement device that can suppress both a decrease in wavelength resolution and a decrease in detection accuracy in measuring light to be measured.

[0010] Technical means of solving problems

[0011] One aspect of the present disclosure is a spectroscopic measurement device, [1] "a spectroscopic measurement device comprising: a light incident portion for incident light to be measured; a reflective diffraction grating for spectrally separating the light to be measured incident from the light incident portion; a photodetector for detecting the light to be measured dispersed by the reflective diffraction grating; a lens for guiding the light to be measured incident from the light incident portion to the reflective diffraction grating and forming a spectral image of the light to be measured dispersed by the reflective diffraction grating in a light receiving area of ​​the photodetector; and an analysis portion for generating spectral data of the light to be measured, the light receiving area comprising: a first light receiving area including 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 area The light detector is provided in parallel with the first light receiving area in a direction perpendicular to the wavelength axis, and includes a plurality of second light detection channels arranged in the direction parallel to the wavelength axis, wherein the light detector outputs first spectrum data of the light to be measured by receiving the spectral image in the first light receiving area with a first exposure time, and outputs second spectrum data of the light to be measured by receiving the spectral image in the second light receiving area with a second exposure time longer than the first exposure time, and the analysis unit generates the spectrum data based on the first spectrum data and the second spectrum data output from the light detector; and the light detector is configured so that a stray light area where stray light generated in an optical path from the light incident portion to the light detector is gathered is located in the first light receiving area.

[0012] In the spectrophotometric device described in [1] above, the light receiving area of ​​the photodetector includes a first light receiving area and a second light receiving area arranged in parallel in a direction perpendicular to the wavelength axis of the spectral image, and the photodetector is arranged so that a stray light area where stray light generated in the optical path from the light incident portion to the photodetector is collected is located in the first light receiving area. Thus, compared with a case where the distance between the light incident portion and the photodetector is increased so that the stray light area is not located in the light receiving area of ​​the photodetector, it is possible to reduce aberration caused by the lens and suppress a decrease in wavelength resolution in the measurement of the light to be measured. Furthermore, in the spectrophotometric device described in [1] above, the photodetector outputs first spectrum data of the light to be measured by receiving the spectral image in the first light receiving area with a first exposure time, and outputs second spectrum data of the light to be measured by receiving the spectral image in the second light receiving area with a second exposure time longer than the first exposure time, and the analysis unit generates spectrum data of the light to be measured based on the first spectrum data and the second spectrum data. Thus, in generating the spectrum data of the measured light, the first spectrum data is used for the high light intensity band and the second spectrum data is used for the low light intensity band in a state where the band corresponding to the stray light region is shifted from the high light intensity band, thereby suppressing the reduction of the detection accuracy in the measurement of the measured light. As described above, according to the spectrophotometry device described in [1], it is possible to suppress both the reduction of the wavelength resolution and the reduction of the detection accuracy in the measurement of the measured light.

[0013] A spectroscopic measurement device according to one aspect of the present disclosure may also be, [2] "a spectroscopic measurement device according to the above-mentioned [1], wherein the analysis unit generates the spectral data based on data of a band that does not include a band corresponding to the stray light region in the first spectral data and data of a band that includes a band corresponding to the stray light region in the second spectral data". In the spectroscopic measurement device described in [2], stray light is detected in the band corresponding to the stray light region in the first spectral data. On the other hand, stray light is not detected in the band corresponding to the stray light region in the second spectral data. Therefore, according to the spectroscopic measurement device described in [2], the influence of stray light can be eliminated from the first spectral data, and the data of the excluded band can be corrected by the second spectral data, thereby further suppressing the reduction in detection accuracy in the measurement of the measured light.

[0014] The spectrophotometer according to one aspect of the present disclosure may be [3] "a spectrophotometer according to [1] or [2] above, wherein the photodetector is offset to one side of the direction perpendicular to the wavelength axis with respect to the light incident portion". According to the spectrophotometer according to [3], the configuration of the photodetector for positioning the stray light region in the first light receiving region can be easily and reliably achieved.

[0015] The spectrophotometric device of one aspect of the present disclosure may be, [4] "a spectrophotometric device according to any one of [1] to [3] above, wherein the stray light is generated due to multiple reflections of a portion of the light to be measured in the lens". The multiple reflections of a portion of the light to be measured in the lens are dominant as the cause of the stray light region. According to the spectrophotometric device described in [4], the reduction in detection accuracy in the measurement of the light to be measured can be further suppressed by eliminating the influence of the stray light region.

[0016] The spectrophotometer according to one aspect of the present disclosure may be [5] "a spectrophotometer according to any one of [1] to [4], further comprising: a shielding member disposed between the lens and the photodetector to block the stray light". According to the spectrophotometer described in [5], the influence of the stray light region can be eliminated by blocking the stray light from entering the photodetector. Therefore, the reduction in detection accuracy can be further suppressed in the measurement of the light to be measured.

[0017] A spectrophotometric device according to one aspect of the present disclosure may be, [6] "a spectrophotometric device according to any one of [1] to [5] above, wherein the lens is a convex lens having a surface facing the light incident portion and the photodetector, and a convex surface facing the reflective diffraction grating". According to the spectrophotometric device described in [6], the measured light incident from the light incident portion can be guided to the reflective diffraction grating, and a spectroscopic image of the measured light dispersed by the reflective diffraction grating can be formed on the light receiving area of ​​the photodetector.

[0018] Effects of the Invention

[0019] According to the present disclosure, it is possible to provide a spectroscopic measurement device that can suppress both a decrease in wavelength resolution and a decrease in detection accuracy in measuring light to be measured. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a diagram showing the structure of a spectrophotometer according to one embodiment.

[0021] Figure 2 It is shown Figure 1 A diagram showing the structure of a photodetector.

[0022] Figure 3 It is a diagram showing the first spectrum data and the second spectrum data.

[0023] Figure 4 It is a diagram showing spectrum data of the light to be measured.

[0024] Figure 5 It is a diagram showing the structure of a photodetector according to a first modified example.

[0025] Figure 6 It is a diagram showing the structure of the photodetector and the spectrum data of the light to be measured according to the second modification. DETAILED DESCRIPTION

[0026] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In addition, the same reference numerals are given to the same or corresponding parts in each figure, and repeated descriptions are omitted.

[0027] [Structure of Spectrophotometer]

[0028] like Figure 1 As shown, the spectroscopic measurement device 1 includes a light incident section 2, a reflective diffraction grating 3, a photodetector 4, a lens 5, and an analysis section 6. The spectroscopic measurement device 1 generates spectrum data of the measurement light L1 by dispersing the measurement light L1.

[0029] The light incident portion 2, the reflective diffraction grating 3, and the lens 5 constitute an optical system (so-called Dyson optical system) for guiding the measured light L1 to the light receiving area 40 of the photodetector 4, and forming a spectral image α of the measured light L1 on the light receiving area 40 of the photodetector 4 along the wavelength axis A. The measured light L1 passes through the reflective diffraction grating 3 and is spectrally dispersed in a direction perpendicular to the incident direction of the measured light L1. Here, the direction in which the measured light L1 is dispersed (i.e., the direction parallel to the wavelength axis A) is referred to as the X-axis direction, the direction perpendicular to the X-axis direction is referred to as the Y-axis direction, and the direction perpendicular to the X-axis direction and the Y-axis direction is referred to as the Z-axis direction.

[0030] The light incident part 2 is configured to allow the measured light L1 to be incident into the spectroscopic measurement device 1. The light incident part 2 adjusts the incident amount of the measured light L1. The light incident part 2 is, for example, a slit member. The slit formed in the slit member opens in a rectangular shape with the X-axis direction as the short side and the Z-axis direction as the long side when viewed from the Y-axis direction. If the width of the short side is increased, the incident amount of the measured light L1 increases, so that spectral data with less noise but low wavelength resolution is obtained in the analysis part 6. On the other hand, if the width of the short side is narrowed, the incident amount of the measured light L1 decreases, so that spectral data with improved wavelength resolution but more noise is obtained in the analysis part 6. The light incident part 2 may also be composed of, for example, a slit member and an optical fiber that transmits the measured light L1 to the slit member. Alternatively, the light incident part 2 may also be composed of, for example, a slit member and a lens structure that focuses the measured light L1 from the outside of the slit member.

[0031] The reflective diffraction grating 3 is opposite to the light incident portion 2 in the Y-axis direction. The reflective diffraction grating 3 splits the measured light L1 to the opposite side of the direction in which the measured light L1 is incident. The reflective diffraction grating 3 is composed of a plurality of grating grooves (not shown). The plurality of grating grooves are arranged in the direction perpendicular to the incident direction of the measured light L1, that is, the X-axis direction, and extend in the direction perpendicular to the arrangement direction, that is, the Z-axis direction. The measured light L1 incident on the reflective diffraction grating 3 is split according to the wavelength in the direction in which the plurality of grating grooves are arranged, that is, the X-axis direction.

[0032] The photodetector 4 is opposite to the reflective diffraction grating 3 in the Y-axis direction. In the present embodiment, the position of the photodetector 4 in the Y-axis direction coincides with the light incident portion 2. The photodetector 4 is arranged on the incident side of the split light L1 to be measured, with a certain distance D between it and the light incident portion 2 in the Z-axis direction. In other words, the photodetector 4 is offset toward the incident side of the split light L1 to be measured along the direction perpendicular to the wavelength axis A (Z-axis direction) relative to the light incident portion 2. The photodetector 4 detects the light L1 to be measured split by the reflective diffraction grating 3. In the present embodiment, the photodetector 4 is a CCD image sensor formed on a semiconductor substrate. The CCD image sensor may also be any of an interline type, a frame transfer type, and a full frame transfer type.

[0033] The lens 5 is arranged between the light incident portion 2 and the photodetector 4 and the reflective diffraction grating 3 in the Y-axis direction. The lens 5 guides the measured light L1 incident from the light incident portion 2 to the reflective diffraction grating 3, and forms a spectroscopic image α of the measured light L1 split by the reflective diffraction grating 3 in the light receiving area 40 of the photodetector 4. The lens 5 is a convex lens having a surface 5a and a convex surface 5b on the opposite side of the surface 5a. The surface 5a faces the light incident portion 2 and the photodetector 4. The surface 5a is a flat surface, a concave surface, or a convex surface. The convex surface 5b is a surface facing the reflective diffraction grating 3 and convexly curved to the opposite side of the surface 5a.

[0034] The analyzing unit 6 generates the spectrum data S3 of the measured light L1 based on the data obtained from the photodetector 4. The content of the analysis by the analyzing unit 6 will be described later. The analyzing unit 6 includes: a storage unit for storing the data obtained from the photodetector 4 and the analysis results. In addition, the analyzing unit 6 can also control the photodetector 4. The analyzing unit 6 can also be a computer or a tablet terminal having 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). In addition, the analyzing unit 6 can also be composed of a microcomputer or an FPGA (Field Programmable Gate Array).

[0035] In the spectroscopic measurement device 1 configured as described above, the light to be measured L1 incident from the light incident portion 2 is incident with respect to the surface 5a at a certain incident angle. The light to be measured L1 incident on the surface 5a is refracted on the surface 5a according to the difference between the refractive index of air and the refractive index of the lens 5, travels in the lens 5, and is emitted from the convex surface 5b. The light to be measured L1 emitted from the convex surface 5b is refracted on the convex surface 5b according to the difference between the refractive index of the lens 5 and the refractive index of air, and is guided to the reflective diffraction grating 3 at the subsequent stage.

[0036] The measured light L1 split by the reflective diffraction grating 3 is incident again on the lens 5. The lens 5 allows the split measured light L1 to be incident at a certain incident angle with respect to the convex surface 5b. The split measured light L1 incident on the convex surface 5b is refracted on the convex surface 5b according to the difference between the refractive index of the air and the refractive index of the lens 5, and travels in the lens 5 to be emitted from the surface 5a. The split measured light L1 emitted from the surface 5a is refracted on the surface 5a according to the difference between the refractive index of the lens 5 and the refractive index of the air, and is imaged on the photodetector 4 at the subsequent stage, forming a split image α on the light receiving area 40.

[0037] Here, stray light may be generated between the optical paths from the light incident portion 2 to the photodetector 4. For example, stray light L2 may be generated due to multiple reflections of a part of the measured light L1 in the lens 5. For example, a part of the measured light L1 incident from the light incident portion 2 or a part of the measured light L1 split by the reflective diffraction grating 3 may be multiple reflected between the surface 5a and the convex surface 5b, and may be emitted from the surface 5a as stray light L2. The stray light L2 may appear as an unnatural peak in the spectrum data. The photodetector 4 can avoid the stray light L2 from being incident on the photodetector 4 if the distance D is increased. However, if the distance D is increased, the displacement of the imaging position due to the difference in wavelength becomes larger, and as a result, the wavelength resolution is reduced. In the present embodiment, the distance D is set so that the region (stray light region β) where the stray light L2 is gathered is located in the first light receiving region 41 in the light receiving region 40 of the photodetector 4.

[0038] [Structure of Photodetector]

[0039] like Figure 2 As shown, the light receiving area 40 of the photodetector 4 is divided into a first light receiving area 41 and a second light receiving area 42. The first light receiving area 41 and the second light receiving area 42 are arranged in a direction perpendicular to the wavelength axis A, that is, in the Z-axis direction. The photodetector 4 has a plurality of first light detection channels 41a arranged in a direction parallel to the wavelength axis A, that is, in the X-axis direction, in the first light receiving area 41. Similarly, the photodetector 4 has a plurality of second light detection channels 42a arranged in a direction parallel to the wavelength axis A, that is, in the X-axis direction, in the second light receiving area 42. Each of the light detection channels 42a, 42b is composed of a plurality of pixels arranged in the Z-axis direction. In addition, the photodetector 4 outputs the first spectrum data S1 of the measured light L1 to each of the plurality of first light detection channels 41a by receiving the spectral image α in the first light receiving area 41 with the first exposure time. At the same time, the light detector 4 can output the second spectrum data S2 of the measured light L1 to each of the plurality of second light detection channels 42a by receiving the spectral image α in the second light receiving area 42 with the second exposure time. The second exposure time is longer than the first exposure time. The spectral image α formed on the light receiving area 40 extends along the wavelength axis A in the X-axis direction and extends along the Z-axis direction for each wavelength. The spectral image α has a shape that is symmetrical in the vertical direction with the boundary line between the first light receiving area 41 and the second light receiving area 42 as the symmetry axis.

[0040] The output of the first spectral data S1 is described in more detail. In the first light receiving area 41, the charges generated and accumulated by the multiple pixels contained in each first light detection channel 41a are transferred to the first shift register (not shown). And, the accumulated charges are added for each first light detection channel 41a in the first shift register (hereinafter, this action is referred to as "vertical transfer"). Thereafter, in the first shift register, the charges added for each first light detection channel 41a are sequentially read out from the first shift register (hereinafter, this action is referred to as "horizontal transfer"). And, a voltage value corresponding to the amount of charge read out from the first shift register is output from the first amplifier (not shown), and the voltage value is converted into a digital value by an AD converter. In this way, the first spectral data S1 is output.

[0041] The output of the second spectral data S2 is described in more detail. In the second light receiving area 42, the charges generated and accumulated by the multiple pixels contained in each second light detection channel 42a are transferred to the second shift register (not shown). And, the accumulated charges are added in the second shift register for each second light detection channel 42a (vertical transfer). Thereafter, in the second shift register, the charges added for each second light detection channel 42a are sequentially read out from the second shift register (horizontal transfer). And, a voltage value corresponding to the amount of charge read out from the second shift register is output from the second amplifier (not shown), and the voltage value is converted into a digital value by an AD converter. In this way, the second spectral data S2 is output.

[0042] In the photodetector 4, the second exposure time of the second light receiving area 42 is longer than the first exposure time of the first light receiving area 41. The exposure time of each area can be set by, for example, an electronic shutter. The electronic shutter can be implemented by using an anti-blooming gate (ABG).

[0043] The stray light region β formed by the collection of the stray light L2 is located in the first light receiving region 41. Specifically, the distance D between the light incident portion 2 and the light detector 4 in the Z-axis direction is set in such a manner that the stray light region β is located in the first light receiving region 41. Here, the distance D is set in such a manner that the stray light region β is not located in the second light receiving region 42. That is, the light detector 4 is configured so that the stray light region β where the stray light L2 generated by the lens 5 is collected is located in the first light receiving region 41 and is not located in the second light receiving region 42. In addition, since the stray light L2 is generated in the lens 5, the position of the stray light region β is adjusted by also adjusting the positional relationship between the lens 5 and the light detector 4. Therefore, in the first spectral data S1, the stray light L2 is detected in the band Δλ corresponding to the stray light region β. On the other hand, in the second spectral data S2, the stray light L2 is not detected in the band Δλ corresponding to the stray light region β. Figure 2 In the example, the stray light region β is an ellipse having a short diameter in the Z-axis direction and a long diameter in the X-axis direction, and the length of the short diameter is longer than the length of the first light receiving region 41 in the Z-axis direction. Therefore, a part of the stray light region β is located in the first light receiving region 41.

[0044] [Method for generating spectrum data of measured light]

[0045] like Figure 3 As shown in (a), the first spectrum data S1 is obtained in the first light receiving area 41 with a short exposure time. The analysis unit 6 can obtain the light intensity of all bands without saturating each pixel in all bands. Figure 3 As shown in (b), the second spectral data S2 is obtained in the second light receiving area 42 with a longer exposure time. The second spectral data S2 includes a band where each pixel is saturated. Therefore, the analysis unit 6 cannot correctly obtain the light intensity in the band where each pixel is saturated. On the other hand, the first spectral data S1 has noise overlap in the band with low light intensity, and the S / N is poor. The second spectral data S2 does not have noise overlap even in the band with low light intensity, and high-precision data can be obtained.

[0046] In the first spectrum data S1, stray light L2 is detected in the wavelength band Δλ corresponding to the stray light region β. The stray light L2 is detected as data such as a bump in the first spectrum data S1. In the first spectrum data S1, the wavelength band Δλ corresponding to the stray light region β is offset from the wavelength band with high light intensity. In other words, the wavelength band Δλ corresponding to the stray light region β is adjusted so as not to overlap with the wavelength band with high light intensity. As an adjustment means, for example, the position of the stray light region β on the first light receiving area 41 is moved along the wavelength axis A.

[0047] The analyzing unit 6 sets a threshold value Th1, which is a light intensity higher than the light intensity of the stray light L2, in the first spectral data S1. The analyzing unit 6 sets a portion above the threshold value Th1 as data S11, and a portion below the threshold value Th1 as data S12 in the first spectral data S1. In other words, the data S11 is data of a band that does not include the band Δλ corresponding to the stray light region β in the first spectral data S1. The data S12 is data of a band that includes the band Δλ corresponding to the stray light region β in the first spectral data S1. Therefore, the data of the detected stray light L2 is included in the data S12. In addition, the data of the band with low light intensity is included in the data S12. On the other hand, the analyzing unit 6 sets a threshold value Th2, which is a light intensity higher than the light intensity of the stray light L2, in the second spectral data S2. The analyzing unit 6 sets a portion above the threshold value Th2 as data S21, and a portion below the threshold value Th2 as data S22 in the second spectral data S2. In other words, data S21 is data of a band that does not include the band Δλ corresponding to the stray light region β in the second spectral data S2. Data S22 is data of a band that includes the band Δλ corresponding to the stray light region β in the second spectral data S2. Here, data of a band in which each pixel is saturated is included in data S21. In addition, the analyzing unit 6 may also set a portion exceeding the threshold value Th1 in the first spectral data S1 as data S11, and a portion below the threshold value Th1 as data S12. In addition, in the second spectral data S2, a portion exceeding the threshold value Th2 may be set as data S21, and a portion below the threshold value Th2 may be set as data S22.

[0048] like Figure 4 As shown, the analyzing unit 6 generates the third spectral data (spectral data of the measured light L1) S3 based on the first spectral data S1 and the second spectral data S2. Specifically, the analyzing unit 6 generates the third spectral data S3 by joining the data S11 and the data S22. The analyzing unit 6 first excludes the data S12 in the first spectral data S1. Furthermore, the analyzing unit 6 cuts out the data S22 in the second spectral data, and joins it with the data S11 in a manner of correcting the excluded data S12 through the data S22. Since the analyzing unit 6 does not use the data S12 including the data in which the stray light L2 is detected when generating the third spectral data S3, the data in which the stray light L2 is detected is excluded from the third spectral data S3. In addition, the analyzing unit 6 does not use the data S21 when generating the third spectral data S3. Therefore, in the third spectral data S3, the light intensity of all bands can be obtained without saturating each pixel in all bands.

[0049] [Function and Effect]

[0050] In the spectrophotometric measuring device 1, the light receiving region 40 of the photodetector 4 includes a first light receiving region 41 and a second light receiving region 42 which are arranged side by side in a direction perpendicular to the wavelength axis A of the spectral image α, and the photodetector 4 is arranged so that the stray light region β where the stray light L2 generated by the lens 5 is collected is located in the first light receiving region 41 and is not located in the second light receiving region 42. Thus, compared with a case where the distance D between the light incident portion 2 and the photodetector 4 is increased so that the stray light region β is not located in the light receiving region 40 of the photodetector 4, the aberration caused by the lens 5 can be reduced, and the reduction in wavelength resolution in the measurement of the light to be measured L1 can be suppressed. Furthermore, in the spectrophotometric device 1, the photodetector 4 outputs the first spectrum data S1 of the light to be measured L1 by receiving the spectral image α at the first light receiving area 41 with the first exposure time, and outputs the second spectrum data S2 of the light to be measured L1 by receiving the spectral image α at the second light receiving area 42 with the second exposure time longer than the first exposure time, and the analyzing unit 6 generates the spectrum data S3 of the light to be measured L1 based on the first spectrum data S1 and the second spectrum data S2. Thus, in generating the spectrum data S3 of the light to be measured L1, the first spectrum data S1 is used for the band with high light intensity, and the second spectrum data S2 is used for the band with low light intensity in a state where the wavelength band Δλ corresponding to the stray light area β is shifted from the wavelength band with high light intensity, so that the reduction in detection accuracy can be suppressed in the measurement of the light to be measured L1. As described above, according to the spectrophotometric device 1, both the reduction in wavelength resolution and the reduction in detection accuracy can be suppressed in the measurement of the light to be measured L1.

[0051] In the spectroscopic measurement device 1, the analysis unit 6 generates the spectrum data S3 based on the data S11 of the band that does not include the band Δλ corresponding to the stray light region β in the first spectrum data S1 and the data S22 of the band that includes the band Δλ corresponding to the stray light region β in the second spectrum data S2. In the spectroscopic measurement device 1, the stray light L2 is detected in the band Δλ corresponding to the stray light region β in the first spectrum data S1. On the other hand, the stray light L2 is not detected in the band Δλ corresponding to the stray light region β in the second spectrum data S2. Therefore, according to the spectroscopic measurement device 1, by eliminating the influence of the stray light L2 from the first spectrum data S1 and correcting the data of the excluded band by the data S22 in the second spectrum data S2, the decrease in the detection accuracy in the measurement of the measured light L1 can be further suppressed.

[0052] In the spectrophotometric measuring device 1, the photodetector 4 is offset to one side (the incident side of the spectroscopically measured light L1) in the direction perpendicular to the wavelength axis A relative to the light incident portion 2. Thus, the photodetector 4 can be easily and reliably arranged so that the stray light region β is located in the first light receiving region 41.

[0053] In the spectrophotometric measuring device 1, the stray light L2 is generated in the lens 5, for example, when a part of the light L1 to be measured is reflected multiple times in the lens 5. As a cause of the stray light region β, the multiple reflections of a part of the light L1 to be measured in the lens 5 are dominant. Therefore, by eliminating the influence of the stray light region β, the reduction in detection accuracy in the measurement of the light L1 to be measured can be further suppressed.

[0054] In the spectrophotometric measuring device 1, the lens 5 is a convex lens having a surface 5a facing the light incident portion 2 and the photodetector 4, and a convex surface 5b facing the reflective diffraction grating 3. Thus, the measured light L1 incident from the light incident portion 2 can be guided to the reflective diffraction grating 3, and a spectral image α of the measured light L1 dispersed by the reflective diffraction grating 3 can be formed on the light receiving area 40 of the photodetector 4.

[0055] [Modifications]

[0056] The present disclosure is not limited to the above-mentioned embodiments. Figure 5 As shown, a masking member 7 can be arranged between the lens 5 and the photodetector 4. In this case, the photodetector 4 is also arranged so that the stray light region β is located in the first light receiving region 41 and not in the second light receiving region 42. Among them, the masking member 7 masks the stray light L2 incident on the first light receiving region 41, so the stray light region β is not directly located in the first light receiving region 41. By arranging the masking member 7, the stray light L2 is not detected in the first spectrum data S1. As a result, the stray light L2 can be blocked from being incident on the photodetector 4, thereby eliminating the influence of the stray light L2. Therefore, the reduction in detection accuracy can be further suppressed in the measurement of the measured light L1. The masking member 7 is, for example, a light-shielding film. The size of the outer edge of the masking member 7 when observed from the Y-axis direction can be larger than the size of the outer edge of the stray light region β. The shape of the masking member 7 when observed from the Y-axis direction is not limited to a rectangular shape, and can also be a circular shape, an elliptical shape, or a triangular shape.

[0057] like Figure 6 As shown, the masking member 7 can be used to correct the spectral sensitivity of the photodetector 4 in addition to masking the stray light L2 . Figure 6 (a) is a diagram showing a masking member 7a for the purpose of correcting the spectral sensitivity arranged on the light receiving area 40a which is not divided into the first light receiving area 41 and the second light receiving area 42. The masking member 7a is based on Figure 6 (b) is designed based on the characteristics of the spectral data. Figure 6 The spectrum data shown in (b) is data of the light to be measured L1 generated by the analyzing unit 6 when the masking member 7a is not arranged in the light receiving region 40a. Figure 6The spectral data of (b) is data in which the light intensity is high in the central band (near 500nm) of the measured light L1, and the light intensity is low in the low-band (near 200nm to 300nm) and high-band (near 700nm to 800nm). The design concept of the masking member 7a is specifically as follows. It is designed that the masking member 7a is not configured in the low-band (near 200nm to 300nm). It is designed that the area of ​​the masking member 7a gradually increases after the band 300nm, and the area of ​​the masking member 7a is the largest in the central band (near 500nm). In addition, it is designed that in the high-band (near 700nm to 800nm), the area of ​​the masking member 7a gradually decreases from the central band (near 500nm). In addition, the masking member 7a is designed to match the position of the stray light area β.

[0058] Figure 6 (c) is spectrum data of the light to be measured L1 generated by the analyzing unit 6 when the masking member 7a is arranged in the light receiving region 40a. Figure 6 The spectral data in (c) shows the same Figure 6 The spectral data of (b) has the same characteristics. However, in the band after 300nm, the light intensity is constant. This is because Figure 6 The masking member 7a of (a) corrects the spectral sensitivity. Furthermore, the masking member 7a masks the stray light L2 from entering the light receiving area 40a. As a result, the stray light L2 is not detected in the spectral data after sensitivity correction. Therefore, the influence of the stray light L2 can be eliminated by blocking the stray light L2 from entering the light detector 4. In addition, Figure 6 In (a), the shielding member 7a is divided into two, but as long as the above-mentioned design concept is followed, it can also be an integral shape or divided into three or more structures.

[0059] The photodetector 4 may also 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 by the input of photons as electric charges. The amplifier converts the electric charges accumulated in the photodiode into voltage and amplifies it. The amplified voltage is transmitted to the AD converter for each first light detection channel 41a and each second light detection channel 42a by switching the selection switch of each pixel. The amplified voltage is converted into a digital value by the AD converter and output as the first spectral data S1 and the second spectral data S2.

[0060] The photodetector 4 may also be a CCD-CMOS image sensor. In the case of a CCD-CMOS image sensor, the photodetector 4 has a plurality of signal readout circuits corresponding to each first light detection channel 41a and each second light detection channel 42a. Each signal readout circuit has a transistor and a bonding pad for signal output. A voltage corresponding to the amount of charge transmitted from each first light detection channel 41a and each second light detection channel 42a may be applied to the control terminal of the transistor. Moreover, a current of a magnitude corresponding to the voltage level is output from the output terminal of the transistor and taken out via the signal output bonding pad. The taken out current is converted into a digital value by an AD converter and output as the first spectral data S1 and the second spectral data S2.

[0061] The stray light L2 is not limited to being generated in the lens 5, but may be generated in the optical path from the light incident part 2 to the photodetector 4. For example, it may be generated between the light incident part 2 and the lens 5, between the lens 5 and the reflective diffraction grating 3, or between the lens 5 and the photodetector 4.

[0062] Explanation of symbols

[0063] 1…spectrometric measuring device; 2…light incident section; 3…reflective diffraction grating; 4…photodetector; 5…lens; 5a…surface; 5b…convex surface; 6…analyzing section; 7, 7a…masking member, 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…measured light; L2…stray light; S1…first spectrum data; S2…second spectrum data; S3…spectral data; α…spectral image; β…stray light area.

Claims

1. A spectrophotometric measuring device comprising: a light incident portion for causing the light to be measured to be incident; a reflective diffraction grating for splitting the light to be measured incident from the light incident portion; a photodetector for detecting the light to be measured dispersed by the reflective diffraction grating; a lens that guides the light to be measured incident from the light incident portion to the reflective diffraction grating and forms a spectroscopic image of the light to be measured split by the reflective diffraction grating on a light receiving area of ​​the photodetector; and an analyzing unit that generates spectrum data of the light to be measured, The light receiving area has: a first light receiving region including 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, which is arranged in parallel with the first light receiving region in a direction perpendicular to the wavelength axis and includes a plurality of second light detection channels arranged in the direction parallel to the wavelength axis, The photodetector outputs first spectrum data of the light to be measured by receiving the spectral image at the first light receiving area with a first exposure time, and outputs second spectrum data of the light to be measured by receiving the spectral image at the second light receiving area with a second exposure time longer than the first exposure time, The analyzing unit generates the spectral data based on the first spectral data and the second spectral data output from the photodetector; The photodetector is arranged so that a stray light region where stray light generated in an optical path from the light incident portion to the photodetector is collected is located in the first light receiving region.

2. The spectrophotometer according to claim 1, wherein: The analyzing unit generates the spectral data based on data of a wavelength band that does not include the wavelength band corresponding to the stray light region in the first spectral data and data of a wavelength band that includes the wavelength band corresponding to the stray light region in the second spectral data.

3. The spectrophotometer according to claim 1 or 2, wherein: The photodetector is offset to one side in the direction perpendicular to the wavelength axis with respect to the light incident portion.

4. The spectrophotometer according to claim 1 or 2, wherein: The stray light is generated when a part of the light to be measured is multiply reflected in the lens.

5. The spectrophotometer according to claim 1 or 2, wherein: The device further includes a shielding member disposed between the lens and the photodetector to shield the stray light.

6. The spectrophotometer according to claim 1 or 2, wherein: The lens is a convex lens having a surface facing the light incident portion and the photodetector, and a convex surface facing the reflective diffraction grating.

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