JP2005283178A - Spectrophotometer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an attachment switchable among diffuse reflection measurement, ATR measurement and fiber measurement which are frequently used, with a simple and inexpensive constitution. <P>SOLUTION: In an incident optical system, since an ellipsoidal mirror 33 has a confocal on a focal position A of light whose direction is changed by a plane mirror 31 and on a sample measuring point B(B'), the light whose direction is changed again by a plane mirror 32 is condensed by the ellipsoidal mirror 33 and the sample measuring point B or B' is irradiated therewith. An outgoing optical system has a bilaterally symmetrical constitution with respect to the incident optical system across the sample measuring point, and light going out from the sample measuring point B or B' is condensed by an ellipsoidal mirror 35 and sent to a photodetector through plane mirrors 37, 38. The diffuse reflection measurement can be performed by placing a sample on the sample measuring point B or B', and the ATR measurement can be performed by placing a prism thereon. The optical fiber measurement can be also performed by separating both sample measuring points (focal points) across the optical fiber. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a spectrophotometer, and more particularly, to an accessory device that is installed inside a sample chamber of a spectrophotometer and performs various spectroscopic measurements.

  In the spectroscopic measurement, various measurement methods such as a diffuse reflection measurement method, a total reflection measurement method (ATR method), and a highly sensitive reflection measurement method are used. Therefore, in the conventional spectrophotometer, the measurement is performed by setting individual attachment devices (attachments) designed to cope with such various measurement methods in the sample chamber. For this reason, the user has to prepare as many attachment devices as the number of types of measurement methods, and the cost burden is large. A spectrophotometer described in Patent Document 1 is known as an apparatus for solving such a problem.

  FIG. 6 is a configuration diagram of the attachment device 1 in this conventional infrared spectrophotometer, and FIG. 7 is a diagram showing a positional relationship between the parabolic mirrors 6 and 11 and the sample holder 10 when various measurements are performed. The accessory device 1 includes parabolic mirrors 2, 4, 6, 11, 15 that condense or collimate infrared light, plane mirrors 3, 5, 14, 16 that change the angle of infrared light, and a plane mirror 5. The movable part 7 for changing the position of the parabolic mirror 6, the rotary knob 8 for changing the angle of the parabolic mirror 6, the movable part 12 for changing the positions of the plane mirror 14 and the parabolic mirror 11, and the angle of the parabolic mirror 11 are changed. A sample holder 10 is arranged between the parabolic mirrors 6 and 11, and the transmitted infrared light or reflected infrared light from the sample holder 10 is finally red by the ellipsoidal mirror 17. The light is condensed on the outer detector 18.

  Infrared light from an interferometer (not shown) is collected by the parabolic mirror 2, changed in direction by the plane mirror 3, and incident on the parabolic mirror 4, where it is converted into parallel light. The direction of the infrared light that has become parallel light is changed by the plane mirror 5 and is condensed on the sample holder 10 by the parabolic mirror 6. The infrared light that has passed through the sample held by the sample holder 10 reaches the parabolic mirror 11, is converted again into parallel light, and the direction is changed by the plane mirror 14. Further, the infrared light collected by the parabolic mirror 15 is changed in direction by the plane mirror 16, sent to the ellipsoidal mirror 17, and collected by the ellipsoidal mirror 17 on the infrared detector 18.

  In the case of transmission measurement, the parabolic mirrors 6 and 11 and the sample holder 10 are arranged on a straight line as shown in FIG. When performing highly sensitive reflection measurement, it is necessary to make infrared light incident on the sample at a large incident angle. At this time, as shown in FIG. 7 (b), the movable mirrors 7 and 12 bring the plane mirror 5 and the parabolic mirror 6 and the plane mirror 14 and the parabolic mirror 11 closer to each other than in the case of transmission measurement, and the rotary knobs 8 and 13 To rotate the parabolic mirrors 6 and 11 diagonally downward. As a result, the infrared light collected by the parabolic mirror 6 is reflected obliquely downward, is reflected by the sample held by the sample holder 10 disposed at this focal position, and travels toward the parabolic mirror 11.

  In the case of the diffuse reflection measurement, it is necessary to make the incident angle of the infrared light to the sample smaller than in the high sensitivity reflection measurement. Therefore, as shown in FIG. 7 (c), the plane mirror 5, the parabolic mirror 6, the plane mirror 14, and the parabolic mirror 11 are brought closer to each other by the movable parts 7 and 12, and the parabolic mirrors 6 and 11 are further rotated obliquely downward. In the case of the single reflection total reflection absorption measurement (ATR method), the parabolic mirrors 6 and 11 are rotated obliquely upward as shown in FIG. Condenses infrared light. The light that has entered the prism 19 is internally reflected and exits the prism 19 toward the parabolic mirror 11. By pressing the sample against the inner reflection surface of the prism 19, the infrared total reflection absorption spectrum of the sample surface can be measured.

  As described above, when the conventional accessory device 1 is used, measurement by various measurement methods is achieved according to the movement by the movable parts 7 and 12, the rotation of the rotary knobs 8 and 13, and the installation position of the sample holder. be able to.

JP 2002-372456 A

  The configuration of the conventional accessory device is very flexible and covers most measurement methods, but on the other hand, the structure becomes complicated and the cost becomes high. In addition, since the number of times the light is reflected by the mirror is large, the loss of light is large, which is disadvantageous for increasing the sensitivity. Practically, there are many cases where high flexibility is not required so far, and there is a strong desire to obtain an accessory device at a lower cost even if the measurement method is limited to some extent.

  The present invention has been made in view of the above points, and the object of the present invention is to provide a specific measurement method that is generally used frequently, specifically, a diffuse reflection method, an ATR method, and fiber measurement. Specializing in the law is to provide a spectrophotometer equipped with an attached device which has a relatively simple structure and is inexpensive.

The present invention made to solve the above problems is a spectrophotometer that irradiates a sample with measurement light and detects transmitted light and reflected light from the sample with respect to the measurement light.
a) a plane mirror that reflects the measurement light incident so as to be condensed at a predetermined position from the light irradiation unit, and has a confocal point at the focal position of the light whose direction has been changed by the plane mirror and the sample measurement point; An incident optical system including an ellipsoidal mirror for condensing and irradiating the reflected measurement light on the sample measurement point, and a rotating means for rotating the ellipsoidal mirror about its incident optical axis;
b) an exit optical system including a plane mirror, an ellipsoidal mirror, and a rotating means, which is disposed substantially mirror-symmetrically with the incident optical system with respect to the surface including the sample measurement point;
, And the rotating means of the incident optical system and the outgoing optical system respectively rotate the ellipsoidal mirror, thereby changing the position of the sample measurement point to correspond to different measurement methods.

  As a specific embodiment, the incident optical system and the output optical system are configured as one accessory device, and the accessory device is installed in a sample chamber for setting a sample in a spectrophotometer as necessary, and rotated. It is convenient to adopt a configuration corresponding to a plurality of measurement methods by rotating the incident-side and emission-side ellipsoidal mirrors by means.

  In the spectrophotometer according to the present invention, when both ellipsoidal mirrors are rotated while maintaining symmetry by the rotating means, the distance from the ellipsoidal mirror to the confocal is constant, so that the sample for the incident optical system There are two points where the measurement point and the sample measurement point for the exit optical system coincide. In these two states, the measurement light collected by the ellipsoidal mirror is incident on the sample arranged at the sample measurement point at a predetermined angle, and the reflected light is emitted from the sample at the same emission angle as the incident angle. Is condensed by the ellipsoidal mirror of the output optical system and sent to the optical path in the subsequent stage. Therefore, diffuse reflection measurement can be performed in this state. Also, ATR measurement is possible by arranging, for example, a prism at the sample measurement point in the same optical path. Furthermore, the ellipsoidal mirror is rotated so that the sample measurement point for the incident optical system is separated from the sample measurement point for the output optical system, and the measurement light emitted from the incident optical system is introduced into the optical fiber, On the other hand, when the reflected light or transmitted light guided by the optical fiber is incident on the outgoing optical system, the optical fiber can be measured.

  In the spectrophotometer according to the present invention, the measurement light incident so as to be condensed at a predetermined position from the light irradiator is not collimated at all, and is condensed at the sample measurement point using a plane mirror and an ellipsoidal mirror. Therefore, the configuration of the optical system can be greatly simplified, and the diffuse reflection measurement method, the ATR measurement method, and the fiber measurement, which have such a simple configuration, but are particularly useful for near infrared spectroscopy. Three types of methods can be measured. Therefore, it is possible to provide a spectrophotometer and an accessory device for the spectrophotometer that have high utility value for many users at a low cost. Further, in the spectrophotometer according to the present invention, since the number of mirrors provided on the optical path is small, the loss of light amount is small, and it is advantageous for performing measurement with higher sensitivity than in the past.

  Hereinafter, an embodiment of a spectrophotometer according to the present invention will be described with reference to the drawings. FIG. 5 is a schematic configuration diagram of an infrared spectrophotometer according to the present embodiment.

  Infrared light emitted from the light source 20 is introduced into an interferometer 21 such as a Michelson interferometer, where infrared interference light is generated and applied to the sample chamber 22. Usually, infrared light is collected on a sample 25 arranged at a predetermined position in the sample chamber 22. For example, light transmitted through the sample 25 is collected on an infrared detector 24 by an ellipsoidal mirror 23. An attachment device 30 described later is installed in the sample chamber 22, and diffuse reflection measurement, ATR measurement, and the like can be performed by changing the optical path configuration with the attachment device 30.

  FIG. 1 is a configuration diagram showing an embodiment of the attachment device 30, (a) is a front view, (b) is a left side view, and (c) is a top view. FIG. 2 is an optical path diagram in the case where diffuse reflection measurement is performed by the accessory device 30, FIG. 3 is an optical path diagram in the case where ATR measurement is performed by the accessory device 30, and FIG. 4 is a case where optical fiber measurement is performed by the accessory device 30. It is an optical path diagram. However, the description of the portions that are difficult to see due to overlapping of components in the drawings is omitted as appropriate.

  As shown in FIG. 1, the attachment device 30 includes, as an incident optical system, plane mirrors 31 and 32 for changing the angle of infrared light, an elliptical mirror 33 for focusing infrared light, and the elliptical surface. And a rotation knob 34 for rotating the mirror 33 about the incident optical axis S. Further, as the output optical system, plane mirrors 37 and 38 for changing the angle of infrared light, an elliptical mirror 35 for focusing infrared light, and the elliptical mirror 35 correspond to the incident optical axis S. And a rotary knob 36 for rotating around the outgoing optical axis S ′.

  Infrared light arriving from an interferometer (not shown) corresponding to the light irradiator in the present invention is first redirected by the plane mirror 31 in the upward direction. When the plane mirror 31 does not exist, the focal point of the incident infrared light is P, but the focal point when reflected by the plane mirror 31 is the position A. The infrared light is further reflected forward by a plane mirror 32 disposed immediately above the plane mirror 31. In front of the plane mirror 32, an ellipsoidal mirror 33 having the focal position A on the optical axis of the light reflected by the plane mirror 31 and the sample position B or B ′ as a confocal point is disposed. It is reflected by the mirror 33 and collected at the sample position. The exit optical system is arranged symmetrically with the incident optical system around the sample position, and the light reflected by the sample passes through an ellipsoidal mirror 35 and a plane mirror 37 as will be described later, and is confocal with the ellipsoidal mirror 35. After forming an image once at the position C, the light is reflected by the plane mirror 38 and guided to the optical path toward the infrared detector.

  By means of the rotary knobs 34, 36, the incident-side ellipsoidal mirror 33 can be rotated about the incident optical axis S, and the output-side ellipsoidal mirror 35 can be rotated about the outgoing optical axis S ′. A reflection optical system is formed regardless of whether the incident angle is upward or downward. When the two ellipsoidal mirrors 33 and 35 are rotated in a state in which left-right symmetry is maintained, one of the focal positions A and C of the ellipsoidal mirrors 33 and 35 is fixed, but the other focal position moves, and FIG. The focal points of the two ellipsoidal mirrors 33 and 35 coincide at the position of the sample position B or B ′ shown in FIG. As is clear from the above description, in this attachment device 30, infrared light is not collimated at any position, and an optical path is formed so as to focus on the sample position B or B '.

  Next, a measurement method using the accessory device 30 will be described. First, when performing powder measurement or particularly diffuse reflection measurement on a small amount of sample, as shown in FIG. 2, the ellipsoidal mirrors 33 and 35 are rotated obliquely downward so that the above-mentioned sample position B ′ is focused. To come. Then, the sample 40 accommodated in the container is disposed at the sample position B ′. At this time, the infrared light collected by the ellipsoidal mirror 33 strikes the sample 40 at a predetermined incident angle, and the reflected light from the sample 40 is collected by the ellipsoidal mirror 35 and sent to the subsequent stage.

  When performing ATR measurement, as shown in FIG. 3, the ellipsoidal mirrors 33 and 35 are rotated obliquely upward so that the sample position B is in focus. Then, for example, a hemispherical prism 19 that satisfies the total reflection condition is disposed at the sample position B. At this time, the infrared light collected by the ellipsoidal mirror 33 is incident on the prism 19, and the light entering the prism 19 is internally reflected and exits the prism 19 toward the ellipsoidal mirror 35. By pressing the sample against the inner reflection surface of the prism 19, the infrared total reflection absorption spectrum of the sample surface can be measured.

  Of course, it is also possible to perform diffuse reflection measurement with the optical path configuration shown in FIG. Practically, in order to measure a part of a large sample or a sample stored in a bottle or bag, it is often convenient to place the sample at the sample position B in this way. Similarly, it is possible to perform ATR measurement with the optical path configuration shown in FIG.

  When optical fiber measurement is performed, as shown in FIG. 4, for example, the ellipsoidal mirrors 33 and 35 are rotated directly upward, and the focal positions of the ellipsoidal mirrors 33 and 35 are separated. A light entrance of the optical fiber 50 is provided at the focal position on the elliptical mirror 33 side, and a light exit of the optical fiber 50 is provided on the focal position on the elliptical mirror 35 side. Infrared light entering the optical fiber 50 from the light entrance is guided again by the optical fiber 50 via the fiber probe 51 and returned to the elliptical mirror 35 from the light exit. By acquiring the reflected light and transmitted light of the sample with the fiber probe 51, the infrared spectrum of the reflected light and transmitted light can be measured. In this case, as long as the light entrance and the light exit of the optical fiber 50 are provided at the focal positions of the ellipsoidal mirrors 33 and 35, the rotation angles of the ellipsoidal mirrors 33 and 35 are arbitrary.

  In this embodiment, the sample position can be switched in the vertical direction by rotating the ellipsoidal mirror. However, it is obvious that a configuration in which the sample position can be switched in the horizontal direction using a similar mechanism is obvious.

  Further, the above embodiment is an embodiment of the present invention, and it is obvious that modifications and changes can be made as appropriate within the scope of the gist of the present invention. For example, an optical system as an accessory device in the above embodiment may be incorporated in a part of the spectrophotometer.

BRIEF DESCRIPTION OF THE DRAWINGS The front view (a), the left view (b), and the top view (c) which show the structure of the attachment apparatus of the spectrophotometer which is one Example of this invention. The optical path figure in the case of performing a diffuse reflection measurement with the attached apparatus by a present Example. The optical path figure in the case of performing ATR measurement with the attached apparatus by a present Example. The optical path figure in the case of performing an optical fiber measurement with the attached apparatus by a present Example. The schematic block diagram of the spectrophotometer of a present Example. The block diagram of the attachment apparatus in the conventional infrared spectrophotometer. The side view which shows the positional relationship of the parabolic mirror and sample holder when performing various measurements with the conventional accessory apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 19 ... Prism 20 ... Light source 21 ... Interferometer 22 ... Sample chamber 23 ... Ellipsoidal mirror 24 ... Infrared detector 30 ... Attached apparatus 31, 32, 37, 38 ... Plane mirror 33, 35 ... Ellipsoidal mirror 34, 36 ... Rotation Knob 40 ... Sample 50 ... Optical fiber 51 ... Fiber probe

Claims (2)

In a spectrophotometer that irradiates a sample with measurement light and detects transmitted light or reflected light in the sample with respect to the measurement light,
a) a plane mirror that reflects the measurement light incident so as to be condensed at a predetermined position from the light irradiation unit, and has a confocal point at the focal position of the light whose direction has been changed by the plane mirror and the sample measurement point; An incident optical system including an ellipsoidal mirror for condensing and irradiating the reflected measurement light on the sample measurement point, and a rotating means for rotating the ellipsoidal mirror about its incident optical axis;
b) an exit optical system including a plane mirror, an ellipsoidal mirror, and a rotating means, which is disposed substantially mirror-symmetrically with the incident optical system with respect to the surface including the sample measurement point;
The spectrophotometer is characterized by changing the position of the sample measurement point by rotating the ellipsoidal mirrors by the rotating means of the incident optical system and the outgoing optical system, respectively.   2. The incident optical system and the output optical system are configured as one attached device, and the attached device is installed as necessary in a sample chamber for setting a sample. Spectrophotometer.

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