JP2015001424A - Spectrophotometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a two-beam spectrophotometer capable of suppressing a level difference in a spectrum caused by slit width switchover by equalizing measurement accuracy per wavelength in spectral measurement.SOLUTION: A spectrophotometer has a single rotary slit plate 12 having an incident slit 12a formed so that a slit width expands successively in accordance with rotary drive displacement in a clockwise (CW) direction and an emission slit 12b formed in point symmetry with the incident slit 12a centering around a rotation axis. One of a first transmitted beam having penetrated a reference sample and a second transmitted beam having penetrated a measurement sample whichever having larger luminous energy than the other is made to be a reference transmitted beam, and the rotary drive displacement of the rotary slit plate 12 is determined so that the luminous energy of the reference transmitted beam falls within a prescribed range.

Description

  The present invention relates to a two-beam spectrophotometer, and more particularly to a two-beam spectrophotometer provided with a variable slit mechanism.

  Conventionally, in a general two-beam spectrophotometer, the energy of the light source, the efficiency of the optical system including the diffraction grating, and the sensitivity of the photodetector change according to the wavelength of the measurement light. The signal level fluctuates and the measurement accuracy fluctuates. In order to suppress such fluctuations in measurement accuracy according to the wavelength, the following means are used in each of the ultraviolet visible region and the infrared region.

  In the UV-visible region, a differential feedback method is used to correct the applied voltage (sensitivity) of the photomultiplier tube (photodetector) based on the larger of the reference light signal R and sample light signal S each time data is captured. ing. On the other hand, photo detectors such as PbS photoconductive elements and InGaAs photodiodes are used in the infrared region, and the sensitivity cannot be corrected as in the UV-visible region, so the slit light width is switched to adjust the amount of measurement light. Thus, control for suppressing fluctuations in the signal level of the measurement light is performed.

  Examples of spectrophotometers equipped with a variable slit mechanism capable of switching the slit width are described in Patent Documents 1 and 2. In the spectrophotometer described in Patent Document 1, the slit width is switched by rotationally driving a slit plate in which a plurality of slits having different widths are formed. On the other hand, in the spectrophotometer described in Patent Document 2, a slit is formed by a gap between two edges, and the slit width is adjusted by driving these edges in the opposite direction.

JP 61-281926 A JP 58-108427 A

  In the spectrophotometer described in Patent Document 1, in the near-infrared region, the difference between the wavelengths of the measurement light is reduced by switching the slits, and adjustment is performed so as to suppress fluctuations in signal accuracy. However, since the selectable slit width is limited, when the slit is switched, the amount of light and the light beam size greatly vary, so that the measurement accuracy may vary at wavelengths before and after the switching, and a step may occur on the spectrum. The step generated on the spectrum can be reduced by spectrum correction or the like, but it is difficult to completely eliminate the influence.

  When measuring with a spectrophotometer equipped with a slit mechanism shown in Patent Document 2, it is difficult to adjust the slit width strictly, and there is a problem that the measurement accuracy varies.

  An object of the present invention is to provide a two-beam spectrophotometer capable of uniforming measurement accuracy for each wavelength in spectrum measurement and suppressing a step on the spectrum caused by switching of the slit width.

  In order to solve the above-described object, the present invention is directed to a light source that generates light including a plurality of wavelength components and monochromatic light of a selected wavelength by splitting incident light incident from the light source into monochromatic light for each wavelength. , A light splitter that divides the output light emitted from the spectrometer into a first measurement light that irradiates the reference sample and a second measurement light that irradiates the measurement sample, and transmits the reference sample In a two-beam spectrophotometer comprising a photodetector that detects the first transmitted light and the second transmitted light that has passed through the measurement sample, it is provided on the optical path of the incident light, and continuously according to the drive displacement. An entrance slit plate having an entrance slit formed so that the slit width is enlarged or reduced, and an exit slit having an exit slit provided on the optical path of the exit light and formed in the same manner as the entrance slit. Plate and slit on the incident side A slit driving unit that drives the plate and the exit-side slit plate in the same direction and a larger one of the first transmitted light and the second transmitted light is used as a reference transmitted light, and the amount of the reference transmitted light Includes a slit control unit that determines driving displacement of the incident side slit plate and the output side slit plate by the slit driving unit.

  According to the present invention, it is possible to make the measurement accuracy for each wavelength uniform in spectrum measurement and to suppress a step on the spectrum caused by switching the slit width.

It is a figure which shows the structure of the two-beams spectrophotometer which concerns on the 1st Embodiment of this invention. It is a figure which shows the structure of the spectrometer which concerns on the 1st Embodiment of this invention. It is a figure which shows the structure of the slit board which concerns on the 1st Embodiment of this invention. It is a figure which shows the structure of the slit board which concerns on a prior art. It is a figure which shows the slit position determination flow which concerns on the 1st Embodiment of this invention. It is a figure which shows the spectrum measurement result by the two-beam spectrophotometer which concerns on a prior art. It is a figure which shows the spectrum measurement result by the two-beams spectrophotometer which concerns on embodiment of this invention. It is a figure which shows the slit position determination flow which concerns on the 2nd Embodiment of this invention. It is a figure which shows the slit position determination flow which concerns on the 3rd Embodiment of this invention. It is a figure which shows the structure of the spectrometer which concerns on the 4th Embodiment of this invention. It is a figure which shows the structure of the slit board which concerns on the 4th Embodiment of this invention.

Embodiments of the present invention will be described below with reference to the drawings.
<First Embodiment>
FIG. 1 is a diagram showing a configuration of a two-beam spectrophotometer according to the first embodiment of the present invention. The two-beam spectrophotometer irradiates the reference sample and the measurement sample with measurement light generated from the same light source, and measures the transmittance of the measurement sample based on the amount of light (energy) of the transmitted light transmitted through the reference sample. . A two-beam spectrophotometer 100 according to the present embodiment includes a light source 1, a spectrometer 2, a light splitter 3, a reference sample placement unit 5, a measurement sample placement unit 7, a photodetector 8, and data. A processing unit 9 and a slit control unit 10 are provided.

  The light source 1 generates light including a plurality of wavelength components. As the light source 1, a deuterium lamp and a halogen lamp are generally used. The spectroscope 2 splits the incident light from the light source 1 into monochromatic light for each wavelength, and emits monochromatic light with a selected wavelength. The outgoing light (monochromatic light) emitted from the spectroscope 2 is split by the light splitter 3 into two light beams, a reference side light beam 4a (first measurement light) and a sample side light beam 6a (second measurement light). The light splitter 3 includes a method of dividing into a reference side light beam and a sample side light beam by rotating a mirror, and a method of dividing by a half mirror such as a beam splitter. The reference-side light beam 4 a enters the reference sample setting unit 5 and is irradiated to the reference sample held by the reference sample setting unit 5. The sample-side light beam 6 a is incident on the measurement sample setting unit 7 and is irradiated on the measurement sample held in the measurement sample setting unit 7. The light 4b (first transmitted light) transmitted through the reference sample and the light 6b (second transmitted light) transmitted through the measurement sample are detected by the photodetector 8. As the photodetector 8, a photomultiplier tube is used in the ultraviolet-visible region, and a detector such as a PbS photoconductive element or an InGaAs photodiode is used in the infrared region. When the light splitting type light splitter 3 by rotating the mirror is used, the transmitted light 4b and 6b are alternately switched by the light detector 8 composed of a single photomultiplier tube or a detector for the infrared region. To detect. On the other hand, when the light splitting type light splitter 3 using a half mirror such as a beam splitter is used, the transmitted light 4b and 6b are simultaneously detected by the light detector 8 composed of two detectors. The data processing unit 9 converts the detection signal input from the photodetector 8 into an energy value and outputs the energy value to the slit control unit 10. The slit control unit 10 controls a slit driving unit (not shown) provided in the spectrometer 2 based on the energy value input from the data processing unit 9.

  FIG. 2 is a diagram showing a configuration of the spectrometer 2 according to the present embodiment. The spectrometer 2 according to the present embodiment includes a light source mirror 11, a rotating slit plate 12, a slit motor 13 (slit driving unit), a parallelizing mirror 14, a diffraction grating 15, and a condenser mirror 16. ing. Since the spectroscope 2 according to the present embodiment is configured so that the optical path of incident light and the optical path of outgoing light are parallel to each other, the spectroscope 2 is rotatably provided on the optical paths of both incident light and outgoing light. A single rotating slit plate 12 can adjust the amounts of both incident light and outgoing light.

  A light beam (incident light) emitted from the light source 1 and incident on the spectroscope 2 is collected by the light source mirror 11 and passes through the entrance slit 12 a of the rotary slit plate 12. The light that has passed through the entrance slit 12 a of the rotary slit plate 12 is converted into parallel light by the parallelizing mirror 14 and is split into monochromatic light for each wavelength by the diffraction grating 15. Of the monochromatic light that has been split, monochromatic light having a wavelength selected according to the angle of the diffraction grating 15 is collected by the condenser mirror 16, passes through the exit slit 12 b of the rotary slit plate 12, and is emitted as measurement light. The The rotating slit plate 12 is rotated by the slit motor 13 to change the slit widths of the incident slit 12a and the outgoing slit 12b, thereby adjusting the light quantity of the measurement light determined by the incident light quantity and the outgoing light quantity. The slit motor 13 is driven and controlled by the slit controller 10 (shown in FIG. 1).

  FIG. 3 is a diagram showing the configuration of the rotary slit plate 12 and shows a state of the slit motor 13 (shown in FIG. 2) viewed from the rotation axis direction. The rotating slit plate 12 is formed in a point-symmetric manner with the incident slit 12a formed so that the slit width continuously increases in accordance with the rotational driving displacement in the clockwise (CW) direction, and the incident slit 12a with the rotation axis as the center. And an exit slit 12b. Further, the spectroscope 2 according to the present embodiment (shown in FIG. 2) has a height h including the rotation axis of the rotary slit plate 12 by a light shielding plate (not shown) provided separately from the rotary slit plate 12. It is configured so that light does not pass through areas other than the above area (light passage area P). Therefore, incident light passes through a rectangular region having a width 12aw and a height h formed by the entrance slit 12a and the light passage region P, and a width 12bw and a height h formed by the exit slit 12b and the light passage region P. The outgoing light passes through the rectangular area. When the rotating slit plate 12 is rotated in the counterclockwise (CCW) direction, the slit widths 12aw and 12bw in the light passing region P are enlarged, and the amount of measurement light determined by the amounts of incident light and outgoing light is increased. On the other hand, when it is rotated in the clockwise (CW) direction, the slit widths 12aw and 12bw in the light passage region P are reduced, and the light amount of the measurement light is reduced. Note that the slits 12a and 12b may be formed so that the slit widths 12aw and 12bw continuously expand according to the rotational drive displacement in the counterclockwise (CCW) direction.

  A slit motor 13 (shown in FIG. 2) that rotates the rotary slit plate 12 is constituted by a step motor, and rotationally drives the rotary slit plate 12 by a certain angle (step angle ΔR). For example, when the slit motor 13 (shown in FIG. 2) is driven with three drive steps, the rotational drive displacement of the rotary slit plate 12 is 3ΔR. The step angle ΔR with respect to the difference between the slit angle R2 (upper limit slit angle) at which the slit widths 12aw and 12bw match the maximum slit width and the slit angle R1 (lower limit slit angle) at which the slit widths 12aw and 12bw match the minimum slit width. Is sufficiently small (R2−R1 >> ΔR), the slit widths 12aw and 12bw can be continuously adjusted. The slit control unit 10 (shown in FIG. 1) has a step number (= R2 / ΔR) (upper limit step number) corresponding to the upper limit slit angle R2 and a step number (= R1 / ΔR) (lower limit) corresponding to the lower limit slit angle R1. The slit motor 13 (shown in FIG. 2) is controlled so as to rotationally drive the rotary slit plate 12 between the lower limit step number and the upper limit step number. Thereby, the slit widths 12aw and 12bw are adjusted between the minimum slit width and the maximum slit width.

  Here, for comparison, a conventional slit slit plate will be described. FIG. 4 is a diagram illustrating a configuration of a rotary slit plate according to the related art. The rotary slit plate 17 according to the prior art is formed in point symmetry with the incident slit 17a composed of a plurality of slits having different widths and the incident slit 17a around the rotation axis so that the stepwise slit width can be switched. And an exit slit 17b. In the rotary slit plate 17 configured in this way, since the switchable slit width is limited, continuous slit width switching cannot be performed, and the amount of measurement light greatly varies when the slit width is switched. As a result, the measurement accuracy varies.

~ Slit position determination flow ~
FIG. 5 is a diagram showing a slit position determination flow executed in the spectrum measurement using the two-beam spectrophotometer 100 according to the present embodiment. The slit position determination flow is executed by the slit controller 10 (shown in FIG. 1) every time the wavelength of the measurement light is changed by the spectroscope 2 (shown in FIG. 2). After the slit position is determined by the slit position determination flow, measurement with the measurement light of the wavelength is performed. Hereinafter, the processing content of each step constituting the slit position determination flow according to the present embodiment will be described with reference to FIG.

  In step S1, the amount of light (sample-side energy) of the light (second transmitted light) that has passed through the measurement sample is measured. In step S2, the amount of light (first-side transmitted light) transmitted through the reference sample is measured (reference-side energy). In step S3, the sample side energy (the amount of second transmitted light) and the reference side energy (the amount of first transmitted light) are compared and determined. If it is determined in step S3 that the reference side energy is greater than the sample side energy, the reference side energy is set to the reference energy E in step S4 (the first transmitted light is set as the reference transmitted light). On the other hand, if it is determined in step S3 that the sample side energy is larger than the reference side energy, the sample side energy is set to the reference energy E in step S5 (the second transmitted light is set as the reference transmitted light). Subsequent to step S4 or step S5, in step S6, the ratio (%) of the reference energy E to the detection range of the photodetector 8 (shown in FIG. 1) is determined.

  If it is determined in step S6 that the reference energy E (the amount of reference transmitted light) is greater than 80% and less than or equal to 100% of the detection range (contains within a predetermined range), the slit position is determined in step S11, End the flow. Here, the predetermined range is a range in which the signal level of the light amount is sufficiently large (the SN ratio becomes large) within the detection range of the photodetector 8 and with respect to the detection resolution of the photodetector 8. In the present embodiment, as an example, the detection range is set to be larger than 80% and not larger than 100%. As the predetermined range is set smaller, the uniformity of measurement accuracy for each wavelength is improved. However, it is necessary to set at least larger than the adjustment resolution of the reference energy E (the amount of change in the reference energy E per step angle ΔR). is there. If the predetermined range is set smaller than the adjustment resolution, it is difficult to adjust the light amount so that it falls within the predetermined range.

  If it is determined in step S6 that the reference energy E is 80% or less of the detection range, in step S7, the slit motor 13 (shown in FIG. 2) is rotated in the clockwise (CW) direction with a driving step number of 1. The rotating slit plate 12 (shown in FIG. 3) is rotated in the clockwise (CW) direction. When the rotary slit plate 12 (shown in FIG. 3) rotates in the CW direction, the slit widths 12aw and 12bw (shown in FIG. 3) are enlarged, and the amount of measurement light increases. In step S8, the number of steps (hereinafter, the actual number of steps) corresponding to the current slit angle of the rotary slit plate 12 (shown in FIG. 3) is compared with the upper limit number of steps. If it is determined in step S8 that the actual step number is less than the upper limit step number, steps S1 to S6 are executed again. On the other hand, if it is determined in step S8 that the actual number of steps is equal to or less than the upper limit step, the slit position is determined in step S11, and the flow ends.

  If it is determined in step S6 that the reference energy E is larger than 100% of the detection range, the slit motor 13 (shown in FIG. 2) is rotated in the counterclockwise (CCW) direction with a driving step number 1 in step S9. The rotating slit plate 12 (shown in FIG. 3) is rotated in the CCW direction. When the rotary slit plate 12 rotates in the CCW direction, the slit widths 12aw and 12bw (shown in FIG. 3) are reduced, and the amount of measurement light is reduced. In step S10, the actual step number of the slit motor 13 (shown in FIG. 2) is compared with the lower limit step number.

  If it is determined in step S10 that the actual step number is not less than or equal to the lower limit step number, steps S1 to S6 are executed again. On the other hand, if it is determined in step S10 that the actual step number is equal to or less than the lower limit step number, the slit position is determined in step S11, and the flow ends.

~effect~
In the present embodiment configured as described above, since the amount of the reference transmitted light is kept within a predetermined range even if the wavelength of the measurement light changes, the measurement accuracy for each wavelength is uniformized in the spectrum measurement, and the slit The effect that the step on the spectrum caused by switching the width is suppressed is obtained. This effect will be specifically described with reference to FIGS. 6A and 6B. FIG. 6A is a diagram showing a spectrum measurement result by the two-beam spectrophotometer according to the prior art, and FIG. 6B is a diagram showing a spectrum measurement result by the two-beam spectrophotometer according to the present embodiment. Although a step is generated by switching the slit width on the spectrum shown in FIG. 6A, such a step is not generated on the spectrum shown in FIG. 6B.

The slit position determination flow shown in FIG. 5 can also be applied to the case where the slit position is determined in the time change measurement. In this case, even when the light amount of the measurement light varies with the passage of time, the variation in measurement accuracy with the passage of time can be suppressed by keeping the light amount of the reference transmitted light within a predetermined range.
<Second Embodiment>
FIG. 7 is a diagram showing a slit position determination flow according to the second embodiment of the present invention. In FIG. 7, the same reference numerals are given to the processes equivalent to the slit position determination flow (shown in FIG. 5) according to the first embodiment. The configuration of the two-beam spectrophotometer according to this embodiment is the same as that of the first embodiment (FIGS. 1 to 3). Hereinafter, the slit position determination flow according to the present embodiment will be described with reference to FIG. 7, focusing on differences from the slit position determination flow according to the first embodiment.

  In step S4 or step S5, the reference side energy (the amount of first transmitted light) or the sample side energy (the amount of second transmitted light) is set to the reference energy E (the amount of reference transmitted light), and then the reference energy is set in step S6A. E is determined.

  If it is determined in step S6A that the reference energy E (the amount of reference transmitted light) is greater than 80% and less than or equal to 100% of the detection range (contains within a predetermined range), the slit position is determined in step S11, End the flow.

  In step S6A, when the reference energy E is 80% or less of the detection range, the determination is further performed in units of 10%, and any one of steps S7A to S7H is performed according to the determination result. In FIG. 7, the process when it is determined that it is greater than 0% and 10% or less (step S7A), and it is determined that the reference energy E is greater than 70% of the detection range and 80% or less. Only the process (step S7H) in the case of being performed is illustrated, and the process in the other cases is not illustrated.

  If it is determined in step S6A that the reference energy E is greater than 70% and less than 80% of the detection range, in step S7A, the slit motor 13 (shown in FIG. 2) is rotated in the CW direction with one drive step. If it is determined that it is greater than 0% and less than or equal to 10% of the detection range, the slit motor 13 (shown in FIG. 2) is driven in the CW direction with 30 drive steps. Rotating drive.

  The number of drive steps in each of the above steps S7A to S7H is the reference energy E in each energy range greater than 70% and less than or equal to 80%, ~ (omitted) ~, greater than 0% and less than 10% of the detection range. Is the number of drive steps required to increase the value to greater than 80% and less than or equal to 100% (predetermined range) of the detection range. The number of driving steps corresponding to these energy ranges is obtained in advance by experiments or the like, and as a correlation information between the number of driving steps of the slit motor 13 (shown in FIG. 2) and the reference energy E (the amount of reference transmitted light), a slit is used. It is set in the control unit 10 (shown in FIG. 1).

  Subsequent to any of steps S7A to S7H, in step S8A, a comparison determination is made between the actual step number of slit motor 13 (shown in FIG. 2) and the upper limit step number. If it is determined in step S8A that the actual number of steps does not exceed the upper limit number of steps, the slit position is determined in step S11, and the flow ends. On the other hand, if it is determined in step S8A that the actual step number is greater than or equal to the upper limit step number, the slit motor 13 (shown in FIG. 2) is rotationally driven in the CCW direction until the actual step number matches the upper limit step number in step S8B. In step S11, the slit position is determined, and the flow ends.

  If it is determined in step S6A that the reference energy E is greater than 100% of the detection range, a comparison determination between the actual step number and the lower limit step number is performed in step S10A. If it is determined in step S10A that the actual step number is equal to or less than the lower limit step number, the slit position is determined in step S11, and the flow ends. On the other hand, if it is determined in step S10A that the actual step number is larger than the lower limit step number, the slit motor 13 (shown in FIG. 2) is driven to rotate in the CW direction until the actual step number matches the lower limit step number in step S10B. Then, steps S1 to S6 are executed again.

In the slit position determination flow configured as described above, the same effect as in the first embodiment can be obtained, and the correlation between the number of driving steps of the slit motor 13 (shown in FIG. 2) and the amount of reference transmitted light. By driving the slit motor 13 (shown in FIG. 2) based on the information (steps S7A to S7H), the number of executions of the sample side energy measurement (step S1) and the reference side energy measurement (step S2) is maximized. The number of slits can be determined quickly, and the slit position can be determined quickly.
<Third Embodiment>
FIG. 8 is a diagram showing a slit position determination flow according to the third embodiment of the present invention. In FIG. 8, the same reference numerals are assigned to the processes equivalent to the slit position determination flow (shown in FIG. 5) according to the first embodiment. The configuration of the two-beam spectrophotometer according to this embodiment is the same as that of the first embodiment (FIGS. 1 to 3). Hereinafter, the slit position determination flow according to the present embodiment will be described with reference to FIG. 8 focusing on differences from the slit position determination flow according to the first embodiment.

  In the slit position determination flow according to the present embodiment, the rotating slit plate 12 (shown in FIG. 3) is rotated to the slit position corresponding to the wavelength in step S0 before measuring the sample side energy in step S1. Here, the slit position according to the wavelength means that the reference energy E (the amount of the reference transmitted light) is 80% of the detection range of the photodetector 8 (shown in FIG. 1) with respect to the measurement light of the currently selected wavelength. It is a predetermined slit position that is larger and 100% or less (contains within a predetermined range). The predetermined number of steps corresponding to the predetermined slit position is obtained in advance by experiments or the like for each wavelength of the measurement light, and is set in the slit controller 10 as correspondence information between the wavelength of the measurement light and the predetermined number of steps. Yes.

In the present embodiment configured as described above, the same effects as those of the first embodiment can be obtained, and the correspondence between the wavelength of the measurement light and the predetermined number of steps of the slit motor 13 (shown in FIG. 2). By driving the slit motor 13 (shown in FIG. 2) based on the information (step S0), the sample-side energy measurement (step S1) and the reference-side energy measurement (step S2) performed until the slit position is determined. ) Is suppressed, and the slit position can be determined quickly.
<Fourth embodiment>
FIG. 9 is a diagram showing a configuration of a spectrometer according to the fourth embodiment of the present invention. The spectroscope 2A according to the present embodiment includes an incident side slit plate 18, a diffraction mirror 19, an output side slit plate 20, and a slit driving unit (not shown). In addition, the other structure of the two-beam spectrophotometer which concerns on this Embodiment is the same as that of 1st Embodiment (FIGS. 1-3). Since the spectroscope 2A according to the present embodiment is configured such that the optical path of incident light and the optical path of outgoing light are not parallel, the amount of incident light is adjusted by the incident-side slit plate 18 provided on the optical path of incident light. The light quantity of the outgoing light is adjusted by the outgoing side slit plate 20 provided on the optical path of the outgoing light.

  A light beam (incident light) emitted from the light source 1 and incident on the spectroscope 2A passes through the incident slit 18a of the incident side slit plate 18 provided in the optical path of the incident light, and is split into monochromatic light for each wavelength by the diffraction mirror 19. Is done. Monochromatic light having a wavelength selected according to the angle of the diffraction mirror 19 out of the monochromatic light that has been split passes through the exit slit 20a of the exit side slit plate 20 provided in the optical path of the exit light, and exits as measurement light. Is done.

  FIG. 10 is a diagram illustrating the configuration of the incident-side slit plate 18 and the exit-side slit 20 and shows a state viewed from the optical path direction of the incident light and the outgoing light, respectively. The incident side slit plate 18 has an incident slit 18a formed so that the slit width 18w continuously expands in accordance with the downward (DWN) direction driving displacement, and the output side slit plate 20 is the same as the incident slit 18a. It has the exit slit 20a formed in. The slit drive unit (not shown) according to the present embodiment is configured by combining, for example, a step motor and a rotation / linear motion conversion mechanism, and is driven by interlocking the entrance side slit plate 18 and the exit side slit plate 20 in the vertical direction. To do. When the slit plates 18 and 20 are driven in the downward (DWN) direction, the slit widths 18w and 20w are enlarged, and the amount of measurement light is increased. On the other hand, when driven upward (UP), the slit widths 18w and 20w are reduced, and the amount of measurement light is reduced. Note that the slits 18a and 20a may be formed so that the slit widths 18w and 20w continuously expand in accordance with the driving displacement in the upward (UP) direction.

  The slit position determination flow (FIGS. 5, 7, and 8) according to the first to third embodiments is applied to the spectroscope 2 (shown in FIG. 2) provided with a single rotating slit plate 12 (shown in FIG. 3). Although described as being applied, by replacing the CCW direction and the CW direction in the rotary slit plate 12 (shown in FIG. 3) with the UP direction and the DWN direction in the slit plates 18 and 20, respectively, The present invention is also applicable to the spectrometer 2A (shown in FIG. In that case, the same effect as any of the first to third embodiments can be obtained according to the applied slit position determination flow.

DESCRIPTION OF SYMBOLS 1 Light source 2 Spectrometer 3 Optical splitter 4a Reference side light beam (1st measurement light)
4b Light transmitted through the reference sample (first transmitted light)
5 Reference sample installation part 6a Sample-side light beam (second measurement light)
6b Light transmitted through the measurement sample (second transmitted light)
7 Measurement Sample Placement Unit 8 Photodetector 9 Data Processing Unit 10 Slit Control Unit 11 Light Source Mirror 12 Rotating Slit Plate 12a Incident Slit 12b Outgoing Slit 13 Slit Motor (Slit Drive Unit)
14 Parallelizing mirror 15 Diffraction grating 16 Condensing mirror 17 Rotating slit plate 17a Incident slit 17b Outgoing slit 18 Incident side slit plate 18a Incident slit 19 Diffraction mirror 20 Outgoing side slit plate 20a Outgoing slit

Claims (5)

A light source that generates light including a plurality of wavelength components;
A spectroscope that splits incident light incident from the light source into monochromatic light for each wavelength and emits monochromatic light of a selected wavelength;
A light splitter that divides the emitted light emitted from the spectroscope into a first measurement light that irradiates a reference sample and a second measurement light that irradiates the measurement sample;
In a two-beam spectrophotometer comprising a photodetector for detecting a first transmitted light that has passed through the reference sample and a second transmitted light that has passed through the measurement sample,
An incident-side slit plate having an incident slit provided on the optical path of the incident light and formed so that the slit width continuously expands or contracts according to driving displacement;
An exit-side slit plate provided on the optical path of the exit light and having an exit slit formed in the same manner as the entrance slit;
A slit driving unit that drives the incident side slit plate and the output side slit plate in conjunction with each other in the same direction;
One of the first transmitted light and the second transmitted light having a larger light amount is used as a reference transmitted light, and the incident side slit plate by the slit driving unit and the light are transmitted within a predetermined range. A two-beam spectrophotometer comprising: a slit control unit that determines drive displacement of the exit side slit plate. The two-beam spectrophotometer according to claim 1, wherein
The slit driving unit is composed of a step motor,
The slit controller determines drive displacements of the incident side slit plate and the output side slit plate based on correlation information between the number of steps of the step motor and the amount of the reference transmitted light. Luminous flux spectrophotometer. The two-beam spectrophotometer according to claim 1, wherein
The slit driving unit is composed of a step motor,
The slit control unit performs driving displacement of the incident side slit plate and the output side slit plate based on correspondence information between the wavelength of the measurement light and the number of steps in which the light amount of the reference transmitted light falls within the predetermined range. A two-beam spectrophotometer characterized by determining. In the spectrophotometer in any one of Claims 1-3,
The spectroscope is configured such that the optical path of the incident light and the optical path of the outgoing light are parallel to each other,
The incident-side slit plate and the output-side slit plate are symmetric with respect to the incident slit formed around the rotation axis, with an incident slit formed so that the slit width continuously expands or contracts according to rotational drive displacement. Composed of a single rotating slit plate having an exit slit formed,
The two-beam spectrophotometer, wherein the slit driving unit rotationally drives the rotary slit plate. The two-beam spectrophotometer according to any one of claims 1 to 3,
The incident side slit plate has an incident slit formed so that the slit width continuously expands or contracts according to the vertical drive displacement,
The exit side slit plate has an exit slit formed in the same manner as the entrance slit,
The two-beam spectrophotometer, wherein the slit driving unit drives the incident side slit plate and the output side slit plate in conjunction with each other in the vertical direction.

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