JP5206322B2 - Spectrophotometer - Google Patents

Description

  The present invention relates to a spectrophotometer, and more particularly to a spectrophotometer suitable for a double beam system.

  The spectrophotometer has a double beam method and a single beam method depending on the configuration of the optical path. The double beam method is more advantageous than the single beam method in terms of analysis accuracy because it is possible in principle to cancel the influence of the light amount fluctuation of the light source in the process of calculating the absorbance.

  In a double beam type spectrophotometer, in order to divide monochromatic light extracted by a spectroscope (monochromator) into a sample-side light beam and a reference-side light beam, the light beam is split mainly using a beam splitter, and a rotating sector mirror is used. One of the distribution of the luminous flux is used. The beam splitter method splits monochromatic light into a sample-side light beam and a reference-side light beam at a certain ratio by the beam splitter and irradiates the sample to be measured and the reference sample, and transmits each transmitted light to the two detectors responsible for each light beam. In contrast, it is introduced in parallel.

  On the other hand, the rotating sector mirror method irradiates the sample to be measured and the reference sample by alternately allocating (switching) the monochromatic light to the sample-side light beam and the reference-side light beam by the sector mirror that is driven to rotate at a constant speed. Light is alternately introduced into one detector (see Patent Document 1, etc.). In this configuration, in general, in order to measure a dark signal in a state where light is not incident on the detector, a light-shielding portion that shields light is provided integrally with the rotating sector mirror.

  FIG. 7 is a plan view of a general rotating sector mirror. In the rotating sector mirror 80, reflecting mirrors 82, openings 83, and light shielding portions 84 are alternately provided around an axis 81. Now, assuming that the rotating sector mirror is arranged so that the monochromatic light beam extracted from the spectroscope is located at a position L indicated by a dotted line in FIG. At the position L, the opening 83 → the light shielding portion 84 → the reflecting mirror 82 → the light shielding portion 84 → the opening 83 → the light shielding portion 84 → the reflecting mirror 82 → the light shielding portion 84 comes in this order. That is, as a mode of the rotating sector mirror, as shown in FIG. 8A, passing (S) → shielding (D1) → reflection (R) → shielding (D2) → passing (S) → shielding (D1) → Switching is made in the order of reflection (R) → light shielding (D2). The sample-side light beam is irradiated to the sample to be measured during the passage (S), and the reference-side light beam is irradiated to the reference sample during the reflection (R) period. Further, no light enters the detector during the light shielding period (D1, D2). As a result, in the detector, the sample-side signal is time-divided in the passage (S) period, the reference-side signal is in the reflection (R) period, and the dark signal is in the light-shielding (D1, D2) period. can get.

  An example of the change in the detection signal is shown in FIG. At the boundary of each sector of the rotating sector mirror 80, the signal changes greatly. At this time, the change of the signal is such that rise and dullness occur as shown in the figure. One of the reasons is the restriction of the frequency response including the detector and the amplifier circuit in the subsequent stage, and another reason is that the light beam has a certain diameter as described above, so that the rotating sector This is because it takes a certain amount of time for the light beam to pass through the boundary between the sectors on the mirror.

  The detection signal is sampled at a predetermined sampling period and converted into a digital value in the A / D converter. However, since accurate data cannot be obtained in a range where the signal is not settled as described above, The data can be collected during the period shown in FIG. That is, in FIG. 8C, Ds is a sample-side signal data collection period, Dr is a reference-side signal data collection period, and Dd1 and Dd2 are dark signal data collection periods. As described above, during the period in which the rotating sector mirror 80 rotates once, the ratio of the time during which effective data cannot be collected is large.

  In general, in order to improve the S / N of a measurement value with a spectrophotometer, it is necessary to increase the ratio of the time for actually collecting effective data to the time required for a series of measurement operations. However, in the double beam type spectrophotometer using a rotating sector mirror, as described above, the period during which effective data can be collected in one rotation period of the rotating sector mirror is fragmented, and the time ratio is small. Therefore, it is difficult to improve the S / N of the measured value. Further, when measuring a sample having a high absorbance (for example, about Abs 8 or more) or particularly requiring a high S / N, it is necessary to secure the measurement time accordingly, and the measurement efficiency is lowered.

  The length of the dark signal data collection periods Dd1 and Dd2 is determined by the rotational speed of the rotating sector mirror. However, depending on the type of detector, the dark current gradually decreases from the time when the incident light is blocked. Since the phenomenon is observed, there is a problem that accurate dark signal data cannot be collected if the dark signal data collection periods Dd1 and Dd2 are short.

JP 2001-356049 A

  The present invention has been made to solve the above-mentioned problems, and its main purpose is to increase the ratio of the time during which effective data is collected with respect to the time required for a series of measurement operations, thereby increasing the measured value. It is providing the spectrophotometer which can improve S / N of this.

  Another object of the present invention is to make it possible to collect effective dark signal data by utilizing the time during which a valid data has not been collected in a series of measurement operations. It is to provide a spectrophotometer capable of improving / N and improving the accuracy of dark signal data.

The present invention made to solve the above-mentioned problems is a light source and a spectroscope that extracts monochromatic light from the light emitted from the light source, and the wavelength of the monochromatic light changes by a predetermined wavelength step width every predetermined period. A spectrophotometer comprising: a spectroscope capable of scanning the wavelength of the monochromatic light by driving the spectroscopic element; and a detector for detecting light from the sample with respect to the monochromatic light.
a) light shielding means for shielding a light beam on an optical path from the light source to the detector;
b) upon measuring with a wavelength scan, during the transition wavelength of the predetermined period is a light shielding control means for driving said light shielding means to shield the light beam,
c) signal acquisition means for acquiring a dark signal by the detector when a light beam is shielded by the light shielding means;
It is characterized by having.

  In the spectrophotometer according to the present invention, the spectroscope can scan the wavelength of the monochromatic light to be extracted by mechanically driving a wavelength dispersion element such as a diffraction grating or a prism.

  The light shielding means can be provided at an arbitrary position on the optical path from the light source to the detector as long as it can block the light beam reaching the detector.

  In the spectrophotometer according to the present invention, the spectrophotometer is driven so that the wavelength changes at every predetermined wavelength step in the measurement accompanied by the wavelength scanning over the predetermined wavelength range. For example, in the case of a spectroscope configured to change the wavelength by changing the angle of the diffraction grating by a stepping motor, a predetermined number of pulse signals are input to the stepping motor, so that only an angle corresponding to the number of pulses is input. The diffraction grating rotates, and the wavelength of the monochromatic light changes accordingly. In this case, a period during which the diffraction grating is rotated and a period until the vibration associated therewith is sufficiently settled even after the rotation is completed are the wavelength transition period.

  The light shielding control means drives the light shielding means during the wavelength transition period so that light does not enter the detector. Therefore, the signal obtained by the detector at this time is a dark signal including a dark current and noise of an amplifier at the subsequent stage. Therefore, the signal acquisition unit collects effective dark signal data when the light beam is blocked by the light blocking unit during the wavelength transition period. Conventionally, effective data has not been collected during this period, but effective dark signal data can be acquired because the operation and vibration of the spectrometer accompanying the wavelength shift have no effect on the dark signal.

The spectrophotometer according to the present invention can be applied to a single beam system, but is particularly useful for a double beam system.
That is, as a preferable aspect of the spectrophotometer according to the present invention, the monochromatic light extracted from the spectroscope is divided into a sample-side light beam and a reference-side light beam, and the sample to be measured is placed on the optical path of the sample-side light beam. In the double beam spectrophotometer in which a reference sample is disposed on the optical path of the light beam, the signal acquisition unit acquires a dark signal when the light beam is blocked by the light blocking unit during a wavelength transition period, and a wavelength A sample-side signal and a reference-side signal are acquired after the transfer is completed.

  According to this configuration, conventionally, dark signal data is acquired during a period in which effective data collection has not been performed, and dark signal data is not acquired in a state where the wavelength of monochromatic light extracted by the spectrometer is stable. Only the sample side signal data and the reference side signal data need be acquired. Accordingly, in the time required for a series of measurement operations over a predetermined wavelength range, the ratio of the time for acquiring the sample side signal data and the reference side signal data is increased, and as a result, the S / N of the measured value is obtained. Can be improved.

  In general, when wavelength scanning is performed by mechanically driving a wavelength dispersion element, it takes a certain amount of time to shift from a certain wavelength to the next wavelength due to mechanical operation restrictions. In other words, the time for acquiring dark signal data can be sufficiently secured, so even if it takes time for the dark signal level to settle down from the point of light shielding, the level is sufficiently settled. It becomes possible to collect dark signal data later. Thereby, the accuracy of measured values such as absorbance can be improved.

As one aspect when the spectrophotometer according to the present invention is a double beam system,
In a double beam spectrophotometer in which monochromatic light is divided into a sample-side light beam and a reference-side light beam by a rotating sector mirror, and the sample-side light beam and the reference-side light beam that have passed through the sample to be measured and the reference sample are introduced into one detector. ,
The signal acquisition means may be configured to alternately acquire the sample side signal and the reference side signal after the wavelength shift is completed.

  In this case, the rotating sector mirror is not provided with a light shielding portion, and light shielding for dark signal measurement is performed by the light shielding means. Thereby, the sample-side signal measurement and the reference-side signal measurement can be performed alternately without providing dark signal measurement periods alternately in the middle. Therefore, the frequency of switching of the light beam incident on the detector is reduced, and the occurrence of dead time in which effective data cannot be acquired due to the dullness of the signal at the time of switching can be reduced. As a result, as described above, it is not only necessary to acquire dark signal data in the wavelength stable state of monochromatic light, but there is a time for acquiring effective sample side signal data and a time for acquiring effective reference side signal data. Since each becomes longer, the ratio of time during which valid data can be acquired during one rotation of the rotating sector mirror is further increased, and the S / N of the measured value can be improved.

  In addition, since the light shielding by the light shielding means and the rotation of the rotating sector mirror are irrelevant, if the rotational speed of the rotating sector mirror is reduced, the effective sample side signal data acquisition time and effective within the measurement time for one wavelength. It is possible to lengthen the acquisition time of each reference side signal data. Thereby, the S / N of the measured value can be further improved.

Moreover, as another aspect in case the spectrophotometer which concerns on this invention is a double beam system,
In a double-beam spectrophotometer that splits monochromatic light into a sample-side light beam and a reference-side light beam by a splitter, and introduces the sample-side light beam and the reference-side light beam that have passed through the sample to be measured and the reference sample to separate detectors. ,
The signal acquisition means acquires the sample-side dark signal and the reference-side dark signal when the light beam is shielded by the light-shielding means during the wavelength transition period by two detectors, and after the wavelength transition is completed, the sample side It can be set as the structure which acquires a signal and a reference side signal.

  In a double beam spectrophotometer using a splitter, the sample side signal and the reference side signal can be obtained in parallel by two independent detectors. Therefore, unlike the case of using a rotating sector mirror, Although there is no generation of invalid data due to the switching, conventionally, the time for wavelength transition during wavelength scanning is wasted as in the configuration using the rotating sector mirror. On the other hand, the spectrophotometer according to another aspect described above can perform dark signal measurement at the time of wavelength transition during wavelength scanning, and performs only sample-side signal measurement and reference-side signal measurement when the wavelength is stable. do it. Thereby, S / N of a measured value can be improved.

  In addition, as described above, a sufficient time for acquiring the dark signal data can be secured. For example, by using a semiconductor detector or the like as the detector, it takes time from the time of light shielding until the level of the dark signal settles. Even in such a case, dark signal data can be collected after the level has sufficiently settled. Thereby, the accuracy of measured values such as absorbance can be improved.

  According to the spectrophotometer according to the present invention, in the time required for a series of measurement operations over a predetermined wavelength range, the ratio of time for acquiring sample-side signal data and acquiring reference-side signal data is increased. Thus, the S / N of the measured value can be improved. On the other hand, since sufficient time for acquiring dark signal data can be secured, accurate dark signal measurement is possible, and the accuracy of measurement values such as absorbance can be improved.

In the spectrophotometer of the second embodiment, the monochromatic light extracted from the spectroscope is divided into two of the sample side light beam Ls and the reference side light beam Lr by the beam splitter 31, and the sample side light beam Ls is divided into the sample 13 to be measured. The transmitted light is incident on the second detector 33, the reference side light beam Lr is irradiated on the reference sample 12, and the transmitted light is incident on the first detector 32. Both light beams split by the beam splitter 31 are incident on the two detectors 32 and 33 almost simultaneously. The two A / D converters 34 and 35 A / D convert the detection signals of the detectors 32 and 33 in parallel, and the obtained data is input to the data processing unit 36 in parallel.

  In FIG. 1, light emitted from a light source 1 is introduced into a spectroscope including an entrance slit 2, a diffraction grating 3, an exit slit 4, and a stepping motor 5, and monochromatic light having a predetermined wavelength is extracted. The stepping motor 5 changes the wavelength of the monochromatic light extracted through the exit slit 4 by changing the angle of the diffraction grating 3 that is a wavelength dispersion element with respect to the incident light that has passed through the entrance slit 2. This monochromatic light is alternately sent in the two directions of the two reflecting mirrors 10 and 11 by the rotating sector mirror 8 that is rotationally driven by the motor 9 at a constant speed.

  That is, when the opening 83 comes to the position L of the monochromatic light shown in FIG. 2 with the rotation of the rotating sector mirror 8 (in the range of the passage S in FIG. 2), the monochromatic light hits the reflecting mirror 11 and the sample side The sample 13 is irradiated with the light beam Ls. On the other hand, when the reflecting mirror 82 comes to the position L of the monochromatic light (in the range of reflection R in FIG. 2), the monochromatic light is reflected by the reflecting mirror 82 and then hits the reflecting mirror 10 to become the reference side light beam Lr. The reference sample 12 is irradiated. For example, the sample 13 to be measured is a sample cell filled with a sample solution to be measured, and the reference sample 12 is a sample cell filled with only a solvent. As shown in FIG. 2, the rotating sector mirror 8 has openings 83 and reflecting mirrors 82 alternately about a rotation angle of 90 ° around an axis 81. Therefore, the sample 13 to be measured and the reference sample 12 are alternately irradiated with light for the same period of time, and are absorbed when the light passes through the respective samples 13 and 12.

  The reference-side light beam Lr that has passed through the reference sample 12 is reflected by the reflecting mirror 14, and the sample-side light beam Ls that has passed through the sample 13 to be measured is reflected by the reflecting mirrors 15 and 16, and both are introduced into the detector 17. Regardless of the type of detector 17, an appropriate detector such as a photomultiplier tube, a semiconductor detector such as InGaAs, InAs, or PbS can be used depending on the wavelength band. Of course, a plurality of detectors may be switched according to the wavelength.

  Before the monochromatic light is distributed to the two optical paths, that is, between the exit slit 4 of the spectroscope and the rotating sector mirror 8, a shutter 6 that moves forward and backward with respect to the optical path by driving a motor 7 serves as a light shielding means. It is arranged. When the shutter 6 is retracted from the optical path, the reference-side light beam Lr or the sample-side light beam Ls that has been absorbed enters the detector 17 as described above, and when the shutter 6 is inserted into the optical path, the detector 17 The light is not incident. The drive source of the shutter 6 is not limited to a motor, and any drive source such as a piezoelectric element can be used. In addition, an electronic shutter that transmits and blocks light by electrical control may be used instead of mechanically blocking light. Further, the installation position of the shutter can be arbitrarily determined as long as it is on the optical path from the light source 1 to the detector 17.

  A detection signal from the detector 17 is amplified by an amplifier (not shown) and the like and then input to an A / D converter (ADC) 18 where it is sampled at a predetermined sampling period and converted into a digital value. As a result, data corresponding to the intensity of the light incident on the detector 17 is obtained and input to the data processing unit 19. The data processing unit 19 sorts and stores necessary data based on a control signal from the control unit 20 that controls the motors 5, 7, 9 and the like, and further stores and classifies the predetermined data using the data. By executing the calculation process, the absorbance of the sample to be measured is calculated for each wavelength.

  Next, a characteristic measurement operation in the spectrophotometer of the present embodiment will be described with reference to FIGS. FIG. 3 is a schematic diagram showing a change in detection signal and a data collection period during one rotation period of the rotating sector mirror used in the spectrophotometer of this embodiment. FIG. 4 is a spectrophotometer of this embodiment. It is explanatory drawing of the measurement operation | movement at the time of wavelength scanning in.

  Unlike the conventional rotating sector mirror 80 shown in FIG. 7, the rotating sector mirror 8 does not have a light shielding portion. Therefore, as a mode when the rotating sector mirror 8 makes one rotation, as shown in FIG. 3A, the mode is simply switched in the order of passing (S) → reflecting (R) → passing (S) → reflecting (R). is there. As a result, in the detection signal obtained by the detector 17, as shown in FIG. 3B, the sample side signal and the reflection reference side signal appear alternately. As is apparent from a comparison between FIG. 3 and FIG. 8, in the spectrophotometer of the present embodiment, the number of switching of the light beam (sector boundary) during the period in which the rotating sector mirror 8 makes one rotation is less than half that of the prior art. Thus, the frequency of large changes in the signal is also low. For this reason, the sample-side signal data collection period Ds and the reference-side signal data collection period Dr, which are set so as to avoid signal dullness when the signal changes greatly (switches), become longer and exclude the light-shielding portion. You can extend the time by more than a minute.

  Consider a case where the spectrophotometer of the present embodiment performs wavelength scanning in the range of wavelengths λ1 to λ2 and measures the absorbance over the wavelength range. In this case, as shown in FIG. 4A, for example, the wavelength is decreased stepwise from the longest wavelength λ1 by a predetermined wavelength step width Δλ, and finally set to the shortest wavelength λ2. Of course, wavelength scanning may be performed from the short wavelength side to the long wavelength side. In such wavelength scanning, when changing from a certain wavelength to a next wavelength that differs by a wavelength step width Δλ, the control unit 20 sends a predetermined number of pulse signals to the stepping motor 5. In response to this, the stepping motor 5 rotates by a predetermined angle, the diffraction grating 3 also rotates by a predetermined minute angle, and stops at a position where monochromatic light of the next wavelength is extracted (T1 in FIG. 4B). . However, even if the diffraction grating 3 is stopped, the wavelength is not immediately stabilized due to vibration or the like. Therefore, it waits for a predetermined time T2 required for the vibration to settle.

  In parallel with the driving of the stepping motor 5, the control unit 20 drives the motor 7 so as to shield light from the shutter 6. Then, the shutter 6 is closed only during a period (T1 + T2) during which the diffraction grating 3 is rotated for changing the wavelength and the diffraction grating 3 is subsequently stabilized, so that the light beam does not enter the detector 17. At this time, since the detection signal by the detector 17 becomes a dark signal, the data processing unit 19 collects dark signal data. That is, as shown in FIG. 4 (e), the dark signal data collection period Dd is set during a period during which light is blocked by the shutter 6 in the wavelength transition period T1 + T2 for changing the wavelength.

  Thereafter, when the shutter 6 is opened, as described above, the sample-side light beam Ls transmitted through the sample 13 to be measured and the reference-side light beam Lr transmitted through the reference sample 12 are alternately detected by the detector 17 as the rotating sector mirror 8 rotates. Is incident on. At this time, since the vibration of the diffraction grating 3 is sufficiently contained, the wavelength of the monochromatic light extracted by the spectroscope has a desired value. Although the sample side signal and the reference side signal appear alternately in the detection output by the detector 17, the signal becomes dull at the boundary. Therefore, the data processing unit 19 discards the data near the boundary, and collects data in the sample-side signal data collection period Ds and the reference-side signal data collection period Dr that are alternately set.

  If the sample-side signal data and the reference-side signal data are collected for a predetermined measurement period T3, the control unit 20 sends a predetermined number of pulse signals to the stepping motor 5 again for changing to the next wavelength. The shutter 6 is closed, and dark signal data collection is executed. Thus, while changing the wavelength of the monochromatic light used for measurement up to the shortest wavelength λ2 by a predetermined wavelength step width Δλ, dark signal data is collected during the wavelength transition period, and when the wavelength is stable, the sample side signal data and Collect reference side signal data alternately. Based on the data collected in this way, the data processing unit 19 obtains the absorbance of the sample 13 to be measured for each wavelength, and creates, for example, an absorption spectrum.

  As described above, in the spectrophotometer of this embodiment, incident light to the detector 17 is not required when changing the wavelength during wavelength scanning, that is, during a period when appropriate sample-side signal data and reference-side signal data cannot be obtained. Dark signal data is collected. Further, the rotating sector mirror 8 is not provided with a light shielding portion, and when the changed wavelength is stable, only the sample side signal data and the reference side signal data are collected alternately. Accordingly, the number of effective sample-side signal data and reference-side signal data that can be collected during the period in which the rotating sector mirror 8 makes one rotation increases more than twice as compared with the prior art, so that the S / N of the measured value can be improved. . Also, since one dark signal data collection period Dd is considerably longer than before, even if it takes time until the dark signal level sufficiently settles from the time of light shielding, dark signal data is collected after the dark signal level has settled. You can also As a result, the accuracy of the dark signal data is increased, which contributes to the improvement of the accuracy of the measurement value.

  Compared to conventional double beam spectrophotometers, the dark signal data collection period is separated in time from the sample-side signal data and reference-side signal data collection periods. Since it is caused by the environment, the fluctuation thereof is slow, and the temporal separation as described above has no problem at all.

  Further, in the spectrophotometer of the first embodiment, the shutter 6 for shielding light and the rotating sector mirror 8 are provided independently, so that the rotating sector mirror is not affected at all without affecting the collection of dark signal data. The rotational speed of 8 can be reduced. FIGS. 4F and 4G show an example of a detection signal and a data collection period when the rotation speed is reduced to ½. By reducing the rotation speed in this way, the switching frequency of the light beam during the measurement period T3 for one wavelength is further reduced, so that invalid data associated with signal switching is further reduced. The number of side signal data can be increased. Thereby, further S / N improvement becomes possible.

[Second Embodiment]
The spectrophotometer according to the first embodiment employs a double beam method in which light is alternately distributed in two directions by a rotating sector mirror. However, the present invention is also applicable to a double beam method in which light is divided into two by a beam splitter. Can be applied. FIG. 5 is a block diagram of the main part of the spectrophotometer according to the second embodiment employing this method, and FIG. 6 is an explanatory diagram of the measurement operation during wavelength scanning in the spectrophotometer of the second embodiment. In FIG. 5, the same components as those of FIG.

  In the spectrophotometer of the second embodiment, the monochromatic light extracted from the spectroscope is divided into two of the sample side light beam Ls and the reference side light beam Lr by the beam splitter 31, and the sample side light beam Ls is divided into the sample 13 to be measured. The transmitted light is incident on the second detector 33, the reference side light beam Lr is irradiated on the reference sample 12, and the transmitted light is incident on the first detector 32. Both light beams split by the beam splitter 31 are incident on the two detectors 33 and 34 almost simultaneously. The two A / D converters 34 and 35 A / D convert the detection signals of the detectors 32 and 33 in parallel, and the obtained data is input to the data processing unit 36 in parallel.

  In the spectrophotometer of the second embodiment, the controller 37 executes the driving of the stepping motor 5 for wavelength scanning and the driving of the motor 7 for opening and closing the shutter 6 as in the first embodiment. Further, the dark signal data is collected when the light is blocked by the shutter 6 at the time of wavelength shift, as in the first embodiment. The difference is that after waiting for the vibration of the diffraction grating 3 due to the wavelength change to settle, the light beam enters the detectors 32 and 33 in parallel when the shutter 6 is opened. Therefore, almost all of the measurement period T3 for one wavelength can be used for the sample-side signal data collection period Ds and the reference-side signal data collection period Dr, which is more advantageous than the first embodiment in terms of the S / N of the measurement values. is there.

  Although both the first and second embodiments are double beam type spectrophotometers, the present invention can also be applied to a single beam type spectrophotometer.

  Moreover, the said Example is an example of this invention, Even if it changes suitably, amends, and is added in the range of the meaning of this invention, it is naturally included in the claim of this application.

The block diagram of the principal part of the double beam system spectrophotometer using the rotation sector mirror by one Example of this invention. The top view of the rotation sector mirror currently used for the spectrophotometer of FIG. The schematic diagram which shows the change of the detection signal in one rotation period of the rotation sector mirror currently used for the spectrophotometer of FIG. 1, and a data collection period. Explanatory drawing of the measurement operation | movement at the time of the wavelength scan in the spectrophotometer of a present Example. The block diagram of the principal part of the double beam system spectrophotometer using the beam splitter by the other Example of this invention. Explanatory drawing of the measurement operation | movement at the time of the wavelength scan in the spectrophotometer by another Example. The top view of the conventional common rotation sector mirror. The schematic diagram which shows the change of the detection signal in one rotation period of a rotation sector mirror, and a data collection period in the conventional double beam system spectrophotometer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Light source 2 ... Entrance slit 3 ... Diffraction grating 4 ... Exit slit 5, 7, 9 ... Motor 6 ... Shutter 8 , 80 ... Rotating sector mirror 81 ... Shaft 82 ... Reflecting mirror 83 ... Openings 10, 11, 14, 15 , 16 ... Reflector 12 ... Reference sample 13 ... Samples to be measured 17, 32, 33 ... Detectors 18, 34, 35 ... A / D converter (ADC)
19, 36: Data processing unit 20, 37: Control unit 31: Beam splitter Lr ... Reference-side light beam Ls ... Sample-side light beam

Claims (4)

A light source;
A spectrometer that extracts monochromatic light from the light emitted from the light source, and scans the wavelength of the monochromatic light by driving the spectroscopic element so that the wavelength of the monochromatic light changes by a predetermined wavelength step width every predetermined period. A spectrophotometer comprising a possible spectrograph and a detector for detecting light from the sample relative to the monochromatic light;
a) light shielding means for shielding a light beam on an optical path from the light source to the detector;
b) upon measuring with a wavelength scanning, among the predetermined period, a light shielding control means during the transition wavelengths for driving the light shielding means to shield the light beam,
c) signal acquisition means for acquiring a dark signal by the detector when a light beam is blocked by the light shielding means;
A spectrophotometer comprising: The spectrophotometer according to claim 1, wherein
The monochromatic light extracted from the spectroscope is divided into a sample-side light beam and a reference-side light beam, a sample to be measured is disposed on the optical path of the sample-side light beam, and a reference sample is disposed on the optical path of the reference-side light beam. In the spectrophotometer,
The signal acquisition means acquires a dark signal when a light beam is shielded by the light shielding means during a wavelength transition period, and acquires a sample side signal and a reference side signal after the wavelength transition ends. Spectrophotometer. The spectrophotometer according to claim 2, wherein
In a double beam spectrophotometer in which monochromatic light is divided into a sample-side light beam and a reference-side light beam by a rotating sector mirror, and the sample-side light beam and the reference-side light beam that have passed through the sample to be measured and the reference sample are introduced into one detector. ,
The spectrophotometer characterized in that the signal acquisition means alternately acquires the sample side signal and the reference side signal after the wavelength shift is completed. The spectrophotometer according to claim 2, wherein
In a double-beam spectrophotometer that splits monochromatic light into a sample-side light beam and a reference-side light beam by a splitter, and introduces the sample-side light beam and the reference-side light beam that have passed through the sample to be measured and the reference sample to separate detectors. ,
The signal acquisition means acquires the sample-side dark signal and the reference-side dark signal when the light beam is shielded by the light-shielding means during the wavelength transition period by two detectors, and after the wavelength transition is completed, the sample side A spectrophotometer characterized by acquiring a signal and a reference side signal.

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