JP2010160025A - Spectrophotometer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To move an optical element such as an optical filter for the removal of higher-order light in such a way as to be driven by a drive mechanism for the rotation of a diffraction grating without having to provide a dedicated actuator, a circuit for controlling this, software, or others as a mechanism for detachably inserting the optical element on an optical path. <P>SOLUTION: A drive arm 20 integrated with the diffraction grating 10 of a spectrometer and driven to rotate with the diffraction grating 10 is provided. A support for supporting the optical element 28 detachably arranged on the optical path is a driven arm 22. The driven arm 22 is arranged at a position in contact with the drive arm 20 within the range of rotational angles outside the range of rotation for the wavelength scanning of the diffraction grating 10. The driven arm is constituted in such a way as to be driven by contact with the drive arm 20 and displaced so as to move the optical element 28 between a position on the optical path and a position outside the optical path. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a dispersive spectrophotometer for performing quantitative analysis or qualitative analysis of a sample by irradiating a sample with measurement light and measuring the intensity distribution of the transmitted light or reflected light according to wavelength with a photodetector.

  In the dispersive spectrophotometer, the wavelength of the measurement light is scanned in order to measure the measurement light irradiated to the sample or the measurement light transmitted or reflected through the sample for each wavelength. The wavelength scanning of the measurement light includes a pre-spectral type that performs wavelength scanning before irradiating the sample, and a post-spectral type that performs wavelength scanning of the measurement light transmitted or reflected by the sample.

  In order to perform wavelength scanning, a spectrometer is disposed on the optical path of the measurement light. The spectroscope has a built-in diffraction grating and rotates the diffraction grating directly by a motor or indirectly through a pulley or the like.

  When specific wavelength light wavelength-dispersed by the diffraction grating is extracted through the slit, the extracted light includes high-order light having a frequency that is an integral multiple of the wavelength. Higher order light comes from the diffraction grating. When high-order light is included to an extent that hinders measurement, high-order light is removed by inserting an optical filter. Normally, an optical filter that removes high-order light when performing measurement on the long wavelength side is inserted on the optical path (see Patent Documents 1-4).

  Such an optical filter is an actuator that can be inserted into the optical path and retracted from the optical path so that a filter with a predetermined wavelength characteristic can be inserted into the optical path only when necessary. It is supported by. In the case where a plurality of optical filters are used, the actuator is configured such that these optical filters can be switched and inserted into the optical path.

  Optical elements that are detachably disposed on the optical path of the spectrophotometer include an optical filter for removing higher-order light, a light amount adjusting element such as an aperture for adjusting the light amount, a light adjusting mesh, or a spectroscopic device. A light emitting element that generates light of a specific wavelength for wavelength calibration of the device is also used. The present invention is also directed to such optical elements other than optical filters.

JP-A-5-133808 JP-A-6-138823 JP 2006-91204 A WO2003 / 004982

  In a conventional spectrophotometer, an actuator for inserting an optical filter for removing higher-order light into the optical path of the measurement light or withdrawing it from the optical path is driven in conjunction with the operation of wavelength scanning. Is independent of the mechanism for rotating the diffraction grating for wavelength scanning.

  An optical filter that removes high-order light does not need to be continuously driven for wavelength scanning, and is inserted into the optical path on the longer wavelength side than the specific wavelength and retracted from the optical path on the shorter wavelength side than that wavelength. A discrete switching operation is sufficient. In particular, when the wavelength range to be measured is narrow, one optical element may or may not be present on the measurement optical path. Even when an optical filter is inserted in a wide wavelength range, it is only necessary to switch between two or three types of optical filters at a predetermined wavelength.

  Further, a light amount adjusting element and a light emitting element for wavelength calibration are only inserted into the optical path when necessary.

  As described above, when a dedicated actuator is provided for moving an optical element that does not require such a complicated drive, its control circuit and software for appropriate control are also required. As a result, the apparatus cost and the development cost increase.

  It is an object of the present invention to simplify a mechanism for moving an optical element that is detachably disposed with respect to an optical path.

  Therefore, the present invention provides a mechanism for detachably inserting an optical element such as an optical filter for removing high-order light in the optical path without providing a dedicated actuator, a circuit or software for controlling the actuator, The optical element is moved by following a drive mechanism for rotating the diffraction grating.

  That is, the spectrophotometer of the present invention includes a light source unit that generates light including a plurality of wavelengths, and transmitted light or reflected light generated from a sample in the sample chamber when light from the light source unit is irradiated as measurement light to the sample chamber. A photodetector for detection, a spectrometer having a built-in wavelength dispersion element disposed on an optical path from the light source unit to the sample chamber or an optical path from the sample chamber to the photodetector, and driven to rotate by a motor; A driving arm that is integrated with the wavelength dispersion element and is rotationally driven together with the wavelength dispersion element, an optical element that is detachably disposed on the optical path of the measurement light, or on an optical path branched from the measurement light, and supports the optical element The optical dispersion element is disposed at a position in contact with the drive arm in a rotation angle range outside the rotation range for wavelength scanning of the wavelength dispersion element, and is driven by the contact of the drive arm to pass the optical element to the optical path. A follower support configured to be displaceable so as to be moved between the position of the optical path and a position off the optical path, rotational drive for wavelength scanning of measurement light by a wavelength dispersion element, and the optical element by the drive arm A controller for controlling the driving of the motor in order to perform rotational driving for the movement of the motor.

  In the present invention, since a dedicated drive mechanism for moving an optical element such as an optical filter for removing higher-order light is not provided, the cost is reduced accordingly, and a space for that is not required, and the degree of freedom of equipment configuration is reduced. Will improve.

  The drive mechanism requires a drive source such as a motor, but the influence of electromagnetic waves and heat generated from such a dedicated drive source is eliminated.

It is a schematic plan view showing an example. It is a fragmentary top view which shows the optical element attachment / detachment operation | movement in the Example. It is a graph showing the spectrum for demonstrating attachment / detachment of the optical element in the Example. It is a flowchart which shows the optical element attachment / detachment in the Example. It is a flowchart which shows the operation | movement of the subroutine at the time of the optical filter attachment / detachment in the flowchart of FIG. It is a top view of the part relevant to the optical element attachment / detachment in another Example.

  FIG. 1 represents an embodiment. Here, the light generated from the light source unit 2 is split by the spectroscope 4 to extract a predetermined wavelength, the sample in the sample chamber 6 is irradiated, and the pre-spectral type in which the light transmitted through or reflected by the sample is detected by the photodetector 8. The spectrophotometer will be described as an example. Even if the spectroscope 4 is a post-spectral type in which the spectroscope 4 is disposed between the sample chamber 6 and the photodetector 8, the configuration in the spectroscope 4 is the same. The present invention covers both the pre-spectral type and the post-spectral type.

  In FIG. 1, the optical system is schematically shown, and illustration of a condensing lens and other optical elements not shown in the drawing is omitted.

  The light source unit 2 includes one or a plurality of light sources that generate continuous wavelength light or a plurality of wavelength lights. As such a light source, a single tungsten iodine lamp can be mentioned depending on a measurement wavelength region. When the wavelength range is wide, for example, two types of lamps, a tungsten iodine lamp and a deuterium lamp, are provided, and light from these lamps is switched by a light source switching mirror so that the light from one of the lamps is guided onto the measurement optical path To do.

  A diffraction grating 10 is built in the spectrometer 4 as a wavelength dispersion element. In this example, a concave diffraction grating having a condensing function is used as the diffraction grating 10, but a flat type diffraction grating is used and light is condensed by arranging a condensing mirror on the optical path. Good. An entrance slit 12 is provided in the spectroscope 4 to guide light from the light source unit 2 to the diffraction grating 10, and an exit is provided to the spectroscope 4 to select light having a predetermined wavelength from the light dispersed by the diffraction grating 10. A slit 14 is provided. Light having a single wavelength selected by the exit slit 14 is guided to a sample cell or a flow cell in the sample chamber 6.

  The diffraction grating 10 rotates to disperse light from the light source. The wavelength of the measurement light emitted from the exit slit 14 is scanned by the rotation of the diffraction grating 10. In order to rotate the diffraction grating 10, the diffraction grating 10 is attached to a rotatable support 16. A motor 18 is provided on the support base 16 in order to rotate the diffraction grating 10 via the support base 16. The support base 16 may be a direct drive type attached to the rotation shaft of the motor 18 or may be an indirect drive type in which a space between the rotation shaft of the motor 18 and the support base 16 is connected to a pulley and a belt.

  A driving arm 20 is integrally attached to the support base 16. The drive arm 20 drives the driven arm 22 in contact with the driven arm 22 for putting the optical filter 28 in and out of the optical path.

  The optical filter 28 is for removing a wavelength component that becomes higher-order light from the light generated from the light source unit 2 when performing measurement on the long wavelength side of the measurement light.

  The driven arm 22 is provided in the spectroscope 4, and the optical filter 28 is placed on the optical path 3 so that the optical filter 28 is inserted into or retracted from the optical path 3 between the entrance slit 12 and the diffraction grating 10. It is a mechanism for arrange | positioning so that attachment or detachment is possible. The driven arm 22 is attached so as to be able to rotate around a fulcrum 24. The driven arm 22 is L-shaped, and an optical filter 28 is fixed to the tip of one of the arms. A positioning pin 26a that contacts when the other arm of the driven arm 22 rotates to one side and a positioning pin 26b that contacts when the other arm rotates to the other side are provided. The other arm of the follower arm 22 includes a tension spring 30 between the follower arm 22 and the fixed point 32 so that the other arm maintains a stable posture even when it is in contact with either of the positioning pins 26a and 26b. Is stretched.

  The driven arm 22 is pushed and displaced by the drive arm 20 by contacting the drive arm 20. The optical filter 28 is disposed on the optical path 3 when the driven arm 22 is in contact with the positioning pin 26a, and the optical filter 28 is removed from the optical path 3 when the driven arm 22 is in contact with the other positioning pin 26b. It is moved to the retreat position.

  The photodetector 8 is a photodiode or a photomultiplier having sensitivity in the wavelength range to be measured.

  The rotation of the diffraction grating 10 and the drive arm 20 is driven by the motor 18, and the drive control of the motor 18 is automatically performed by the control unit 34. The control unit 34 can be realized by a computer dedicated to the spectrophotometer or a general-purpose personal computer.

  2A and 2B show the operation when the driven arm 22 is moved by the drive arm 20. FIG. When the optical filter 28 is retracted to a position off the optical path 3 from the state on the optical path 3 as shown in FIG. 1, the drive arm 20 is moved in the clockwise direction from the state shown in FIG. 1 to the state shown in FIG. Rotate approximately 270 degrees with 10. This rotation range is a range beyond the driving range of the diffraction grating 10 with respect to the measurement wavelength range. Furthermore, when the drive arm 20 pushes the driven arm 22 from the left side in the drawing in the state of FIG. 2A and the driven arm 22 further rotates from the position where it starts to rotate counterclockwise by the pulling force of the spring 30, The arm 22 rotates without depending on the force of the drive arm 20 until it abuts against the positioning pin 26b on the opposite side by the pulling force of the spring 30. As a result, as shown in FIG. 2B, the optical filter 28 moves to a position off the optical path 3. Thereafter, the diffraction grating 10 is driven reversely in the counterclockwise direction to return to the original wavelength measurement range, and the subsequent wavelength scanning measurement is continued.

  When the optical filter 28 is inserted into the optical path 3, the drive arm 20 is rotated counterclockwise together with the diffraction grating 10 beyond the drive range corresponding to the measurement wavelength range, as shown in FIG. As shown, the drive arm 20 pushes the follower arm 22 from the right side in the drawing to rotate the follower arm 22 clockwise, and the follower arm 22 does not depend on the force of the drive arm 20 due to the pulling force of the spring 30. Push to a position slightly beyond the position moving in the direction of 26a. As a result, the driven arm 22 is rotated to the position where it abuts against the positioning pin 26 a by the force of the spring 30, and the optical filter 28 is inserted at a position on the optical path 3. Thereafter, similarly, the diffraction grating is returned to the original measurement wavelength range and the subsequent wavelength scanning measurement is continued.

  Returning to FIG. 1, the operation of the spectrophotometer will be described. White light or a plurality of wavelengths introduced from the light source unit 2 through the entrance slit 12 enters the diffraction grating 10 and is wavelength-dispersed. Among them, light in a specific wavelength range (substantially monochromatic light) passes through the exit slit 14 to irradiate the sample in the sample chamber 6, and the transmitted light or reflected light is guided to the photodetector 8 to measure the spectral distribution intensity. Is done. The wavelength of the substantially monochromatic light extracted from the exit slit 14 is selected by the rotation of the diffraction grating 10.

  The control unit 34 rotates the diffraction grating 10 through the support 16 at the time of measurement to perform wavelength scanning, and has a specific wavelength for inserting or removing the optical filter 28 on the optical path 3. At this time, the drive arm 20 is rotated by the motor 18 via the support base 16 and the driven arm 22 is pushed, whereby the optical filter 28 is inserted into or retracted from the optical path 3. The driven arm 22 is restrained by the tension spring 30 in two states in contact with either one of the positioning pins 26a and 26b. As a result, the optical filter 28 is positioned in one of two states: a state in which the optical filter 28 is inserted on the optical path 3 and acts on the incident light;

  It is easy to make the structure in which the range in which the driven arm 22 can be driven and the range in which the wavelength scanning measurement is performed are not overlapped. Thus, the insertion and withdrawal of the optical filter 28 and the movement of the wavelength scanning are completely performed. Can be independent. That is, the measurement sequence can be executed while inserting and retracting the optical filter 28 at an arbitrary wavelength.

  Next, a more specific operation will be described with reference to FIGS.

  FIG. 3 schematically shows the measured spectrum. The wavelength scanning is performed from the long wavelength side to the short wavelength side. The specific wavelength λc is a wavelength for switching whether or not the optical filter 28 is inserted into the optical path 3. On the long wavelength side longer than the wavelength λc, the optical filter 28 is inserted into the optical path 3 in order to remove high-order light. The optical filter 28 is retracted from the optical path 3 on the shorter wavelength side than the wavelength λc.

  FIG. 4 shows the operation at that time. The operation is controlled by the control unit 34. The control unit 34 sets a flag in each of the state where the optical filter 28 is inserted on the optical path 3 and the state where the optical filter 28 is removed from the optical path 3 so that it can be determined which state is present.

  When the measurement is started, it is first determined from the flag whether or not the optical filter 28 is on the optical path 3 (step S1). If it is determined that the optical filter 28 is on the optical path 3, the wavelength λ to be measured is compared with a specific wavelength λc for switching between insertion and withdrawal of the optical filter 28 (step S2). The rotation of the diffraction grating 10 is driven so as to select λ (step S3). If the measurement wavelength λ is equal to or less than λc, a subroutine for removing the optical filter 28 from the optical path 3 is executed (step S4), and a flag indicating that the optical filter 28 is not on the optical path 3 is set. Thereafter, the rotation of the diffraction grating 10 is driven so as to select the measurement wavelength λ (step S3).

  On the other hand, when it is determined in step S1 that the optical filter 28 is not inserted on the optical path 3 by the flag, the wavelength λ to be measured is compared with the specific wavelength λc (step S5), and the measurement wavelength λ is the specific wavelength λc. If it is below, the rotation of the diffraction grating 10 is driven so as to select the measurement wavelength λ as it is (step S3). If the measurement wavelength λ is larger than the specific wavelength λc in step S5, the optical filter 28 is originally a wavelength that is required to be disposed on the optical path 3, and therefore a subroutine for inserting the optical filter 28 on the optical path 3 (Step S6), a flag indicating that the optical filter 28 is on the optical path 3 is set, and then the rotation of the diffraction grating 10 is driven so as to select the measurement wavelength λ (step S3).

  Here, a subroutine for inserting the optical filter 28 onto the optical path 3 and retracting it from the optical path 3 is executed as shown in FIG. 5, and the driven arm 22 is rotated by the drive arm 20.

  Returning to FIG. 4 again and continuing the description, after the measurement at the wavelength position λ (step S7), the diffraction grating 10 is rotated so as to be the next measurement wavelength λ (step S8). The wavelength scanning is performed so as to move to the short wavelength side in units of Δλ. While the next measurement wavelength λ is larger than λc, the measurement is continued while sequentially switching the measurement wavelength to the short wavelength side (steps S9 → S10 → S7 → S8). When the measurement is continued and the next measurement wavelength λ becomes equal to or less than the specific wavelength λc, a subroutine for removing the optical filter 28 from the optical path 3 is executed (step S11 → S12), and the optical filter 28 is not on the optical path 3. Set a flag to indicate that. After that, even if the measurement wavelength is switched to the shorter wavelength side, the flag indicating that the optical filter 28 is out of the optical path 3 is set, so that the optical filter 28 is removed from the optical path 3 thereafter. Without executing this subroutine, the measurement is continued until the measurement end wavelength λend while switching the measurement wavelength to the short wavelength side (steps S7 → S8 → S9 → S10 → S11 → S7 → S8 → S9).

  The optical filter 28 is shown as an optical element detachably disposed on the optical path 3, or the optical element is another optical element such as an aperture or a mesh filter for dimming, or a light emitting element for wavelength calibration. But it can be handled in exactly the same way.

  The mechanism for holding the optical element in a state where it is disposed on the optical path and in a state where the optical element is retracted from the optical path is not limited to the mechanism in which the follower arm is brought into contact with the positioning pin as in the above embodiment, but a mechanism using a plunger, Other mechanisms can also be used.

  The position where the optical element is inserted is not necessarily on the measurement optical path itself, but may be on another optically equivalent optical path branched by a mirror, a half mirror, or the like.

  In the first embodiment, there is one drive arm 20. Therefore, a relatively large rotation angle is required for switching the optical element. On the other hand, in the second embodiment, the support base 16 is provided with two drive arms having different angles.

  Specifically, as shown in FIG. 1, the second drive arm 20 a is provided on the support base 16 at a different angle with respect to one drive arm 20. The drive arms 20 and 20a are both arranged at positions where they contact the driven arm 22 in a rotation angle range outside the rotation range for wavelength scanning by the diffraction grating 10. 2A, when the driven arm 22 is pushed so as to retract the optical element 28 from the optical path 3, the drive arm 20a is used, and the optical element 28 is moved as shown in FIG. When the driven arm 22 is pushed so as to be inserted on the optical path 3, the functions of the drive arms 20 and 20a are made different so that the drive arm 20 is used.

  According to this embodiment, the rotation angle necessary for switching the optical element is smaller than that of the first embodiment, and there is an advantage that the time required for switching the optical element can be shortened.

  In the first embodiment, the driven arm 22 as the driven support performs the function of arranging one optical element 28 on the optical path 3 or retracting it from the optical path 3. On the other hand, this embodiment shown in FIG. 6 is provided with a driven support body that supports a plurality of optical elements and selectively places one of these optical elements on the optical path 3.

  In FIG. 6, an optical element array 28a in which a plurality of optical filters having different absorption wavelength ranges are arranged in a line as an optical element is held by a holder 22a that is a driven support. The holder 22a is supported by the linear guide 40 so as to be movable in a direction crossing the optical path 3, and the optical element array 28a moves so as to sequentially cross the optical path 3 as the holder 22a moves. When the holder 22a moves to a position where any one end of the optical element array 28a deviates from the optical path 3, no optical filter exists on the optical path 3.

  The support base 16 supporting the diffraction grating 10 is provided with a drive arm 20 as in the embodiment of FIG. 1, and the holder 22a is provided with a follower pin 42 at a position where it comes into contact with the drive arm 20. . The holder 22a can move while being guided by the linear guide 40 when the drive arm 20 comes into contact with the driven pin 42 and is pushed by the drive arm 20.

  Between the holder 22a and the linear guide 40, the urging force by the drive arm 20 acts at each of the positions where the optical filters are on the optical path 3 and the position where one end of the optical element array 28a is off the optical path 3. A positioning mechanism for stably holding each position is provided in the absence of the position.

  Various positioning mechanisms can be used, but an example is a plunger and a guide-like mechanism. Another example of such a positioning mechanism is that one pin provided on one of the contact surfaces of the holder 22a and the linear guide 40 and the other of the contact surfaces are fitted with the pin. The notch for positioning the holder 22a with respect to the linear guide 40 is located at a position where each optical filter is on the optical path 3 and one end of the optical element array 28a is off the optical path 3. It is set so that a pin fits into the notch at each position.

  In this embodiment, when the drive arm 20 contacts the driven pin 42 and pushes the holder 22a, the optical filters included in the optical element array 28a can be sequentially switched and arranged on the optical path 3. Further, no optical filter may be present on the optical path 3.

  By changing the direction in which the drive arm 20 abuts on the driven pin 42 and pushes the holder 22a, the optical element array 28a can be moved in both directions as indicated by thick arrows in the drawing.

  In FIG. 6, there is only one drive arm 20, but two drive arms are provided in addition to the drive arm 20 a indicated by the chain line in FIG. 1, and the drive arm to be used is different depending on the direction in which the holder 22 a is pushed. You may do it.

DESCRIPTION OF SYMBOLS 2 Light source unit 3 Optical path 4 Spectrometer 6 Sample chamber 8 Photodetector 10 Diffraction grating 12 Inlet slit 14 Outlet slit 16 Support stand 18 Motor 20, 20a Drive arm 22 Drive arm 22a Holder 26a, 26b Positioning pin 28 Optical filter 28a Optical element Array 30 Tension spring 40 Linear guide

Claims (3)

A light source unit that generates light including multiple wavelengths;
A light detector that irradiates the sample chamber with light from the light source unit as measurement light and detects transmitted light or reflected light generated from the sample in the sample chamber; and
A spectroscope having a built-in wavelength dispersive element disposed on the optical path from the light source unit to the sample chamber or on the optical path from the sample chamber to the photodetector;
A drive arm integrated with the wavelength dispersive element and driven to rotate together with the wavelength dispersive element;
An optical element detachably disposed on the optical path of the measurement light or on the optical path branched therefrom;
The optical element is supported, and is disposed at a position that contacts the drive arm in a rotation angle range outside the rotation range for wavelength scanning of the wavelength dispersion element, and is driven by the contact of the drive arm to move the optical element. A follower configured to be displaceable to move between a position on the optical path and a position off the optical path;
A control unit that controls driving of the motor to perform rotation driving for wavelength scanning of the measurement light by the wavelength dispersion element and rotation driving for movement of the optical element by the drive arm;
Spectrophotometer equipped with.   The spectrophotometer according to claim 1, wherein the optical element includes an optical filter, a light amount adjusting element, or a light emitting element.   The spectrophotometer according to claim 1, wherein the driven support includes a mechanism that supports a plurality of the optical elements and selectively arranges any of the optical elements on an optical path.

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