JP3174573U - Fourier transform infrared spectrometer - Google Patents

Abstract

A Fourier transform infrared for facilitating a change operation of a relative angular position of a semi-transmission plate and a compensation plate to reduce or eliminate interference generated between the semi-transmission plate and a compensation plate constituting a beam splitter. A spectroscopic device is provided.
In a state in which the beam splitter is installed on the beam splitter holder, the semi-transparent plate holder and the compensating plate holder are disposed at positions where the semi-transparent plate and the compensation plate can be fixed and released. By disposing the presser foot, the fixing screw of the presser foot is loosened to release the space between the semi-permeable plate holder 5 and the compensation plate holder 4, and the compensation plate holder 4 can be rotated with respect to the semi-permeable plate holder 5.
[Selection] Figure 1

Description

  The present invention relates to a Fourier transform infrared spectrometer, and more particularly to a beam splitter that constitutes a Fourier transform infrared spectrometer.

  As one of analyzers that quantitatively analyze components contained in a sample, there is a Fourier transform infrared spectrometer according to the Fourier transform infrared spectroscopy (FTIR) method.

  FIG. 5 shows an outline of the configuration of a conventional Fourier transform infrared spectrometer. A Fourier transform infrared spectroscopic device 40 shown in FIG. 5 includes a light source 61 that emits infrared light that irradiates a sample, an optical system 71 that converts infrared light from the light source 61 into parallel light, and an optical system. An interference mechanism 72 that modulates infrared light that has passed through 71, an optical system 73 through which infrared light that has passed through the interference mechanism 72 passes, and a detector 69 that detects infrared light that has passed through the optical system 73. .

  The optical system 71 includes a concave mirror 62, a parabolic mirror 63, and an entrance slit 64. The other interference mechanism 72 includes a beam splitter 21, a fixed mirror 66, and a moving mirror 65, and the optical system 73 includes a parabolic mirror 67 and a concave mirror 68. Further, the sample 70 is installed between the parabolic mirror 67 and the concave mirror 68 and transmits infrared light.

  The beam splitter 21 is installed at a certain angle with respect to the incident infrared light beam, and reflects half of the incident light beam, guides it to the fixed mirror 66, and transmits the other half to move in the direction of the infrared optical axis. Guide to mirror 65. The reflected light from both mirrors is again synthesized by the beam splitter 21, transmitted through the sample 70, detected by the detector 69, and the resulting interference pattern is Fourier transformed in a data processing unit (not shown). Thus, a spectrum is obtained.

  FIG. 6 shows an outline of the configuration of a beam splitter used in a conventional Fourier transform infrared spectrometer. (A) Front view, (b) Right side view (CC sectional view), (c) Top view (DD sectional view), (d) Presser plate, (e) Guide plate. Show. The beam splitter 21 compensates a semi-transparent plate 23 having a semi-transparent material deposition surface on one side of an infrared transmissive material, a compensation plate 22 having the same material and shape as the semi-transparent plate 23, and a semi-transparent plate holder 25, respectively. It arrange | positions in the plate holder 24 and combined both.

  First, after fixing the semi-transparent plate holder 25 and the compensation plate holder 24 with the countersunk screws 36, the semi-transparent plate 23 and the compensation plate 22 are inserted into both holders, respectively, and a guide having a guide hole 28b in the guide portion 28a from both sides. The plate 28 is installed, then the balls 29a and 29b are inserted into the guide holes 28b, and the presser plate 27 is set and fastened with screws 31 and 31a. By this fastening, the heads of the balls 29a and 29b protruding outward from the surface of the guide plate 28 are pressed by the spring portions 27a of the presser plate 27, so that the semi-transparent plate 23 and the compensation plate 22 are compensated with the semi-transparent plate holder 25, respectively. It is fixed to the plate holder 24, and the assembly of the beam splitter 21 is completed.

  Further, in order to reduce or eliminate interference between the semi-transmissive plate and the compensation plate due to surface accuracy, the relative angular positional relationship between the semi-transmissive plate 23 and the compensation plate 22 is changed. Patent Document 1 discloses a method for reducing or removing spectrum noise caused by water vapor or carbon dioxide in the air existing in the optical path.

  The beam splitter 21 is set in a beam splitter holder 55 installed in the Fourier transform infrared spectroscopic device 40. The beam splitter holder 55 includes a frame 56, guides 57 and 58, and a lower guide 59.

JP 2007-108151 A

  When the light beam is incident on two parallel flat plates having the same thickness, the semi-transparent plate and the compensation plate in the above configuration cause interference (Brewster interference) between the semi-transparent plate and the compensation plate due to surface accuracy. Interference fringes appear in the spectrum. As a result, noise is generated in the spectrum, and the S / N ratio and the accuracy of the analysis result are lowered. Conventionally, in order to prevent interference between the semi-transmissive plate and the compensation plate, for example, a method of rotating the compensation plate and changing the interference state of both surfaces has been adopted.

  First, after removing the beam splitter 21 from the beam splitter holder 55, the screw 31 is loosened, and the presser plate 27, the guide plate 28, and the ball 29a are removed. Thereafter, the compensation plate 22 is taken out from the compensation plate holder 24, and the assembly angle is changed and reassembly is performed. The beam splitter 21 is attached to the beam splitter holder 55 again, and the interference state is checked based on the spectrum obtained by operating the apparatus. If the improvement of the interference state is insufficient, it is necessary to repeat the above operation. Therefore, since the result is unknown until the spectrum is confirmed, it is very troublesome.

  In order to solve the above problems, the present invention provides a light source that emits infrared light that irradiates a sample, an optical system that converts infrared light from the light source into parallel light, and infrared light that has passed through the optical system. A Fourier splitter comprising: a beam splitter that modulates light; a fixed mirror and a movable mirror that reflect infrared light reflected and transmitted through the beam splitter; and a detection device that measures infrared light that has passed through the beam splitter. In the conversion infrared spectroscopic device, with the beam splitter installed in the Fourier transform infrared spectroscopic device, the semitransparent plate and the compensation plate constituting the beam splitter are arranged at a position where the work can be fixed and released. A fixing tool is provided, and by releasing the fixing tool, the relative angular position of the compensating plate with respect to the semi-permeable plate can be changed and the angle after the change can be changed And it has a structure that location can be determined.

  The present invention makes it possible to change the relative angular positional relationship between the translucent plate and the compensator without removing the beam splitter from the Fourier transform infrared spectroscopic device. Further, the angular positional relationship can be changed while viewing the spectrum. It is possible to check whether it is optimal, adjustment becomes easy, and adjustment time can be shortened.

The outline | summary of a structure of the Fourier-transform type | mold infrared spectroscopy apparatus by the Example of this invention is shown. The outline of the structure of the beam splitter used for the Fourier-transform-type infrared spectroscopy apparatus by the Example of this invention is shown. (A) is a front view, (b) is a right side view (AA cross-sectional view), and (c) is a top view (BB cross-sectional view). The components figure in the Example of this invention is shown. (A) shows the presser plate and (b) shows the guide plate. The adjustment state of the beam splitter in the Example of this invention is shown. An outline of the configuration of a conventional Fourier transform infrared spectrometer is shown. An outline of the configuration of a beam splitter used in a conventional Fourier transform infrared spectrometer is shown. (A) Front view, (b) Right side view (CC sectional view), (c) Top view (DD sectional view), (d) Presser plate, (e) Guide plate. Show.

  FIG. 1 shows an outline of the configuration of a Fourier transform infrared spectrometer according to an embodiment of the present invention. A Fourier transform infrared spectroscopic device 20 shown in FIG. 1 includes a light source 41 that emits infrared light that irradiates a sample, an optical system 51 that converts infrared light from the light source 41 into parallel light, and an optical system. An interference mechanism 52 that modulates infrared light that has passed through 51, an optical system 53 through which infrared light that has passed through the interference mechanism 52 passes, and a detector 49 that detects infrared light that has passed through the optical system 53.

  The optical system 51 is from the concave mirror 42, the parabolic mirror 43 and the entrance slit 44, the interference mechanism 52 is from the beam splitter 1, the fixed mirror 46 and the moving mirror 45, and the optical system 53 is from the parabolic mirror 47 and the concave mirror 48. Composed. Further, the sample 50 is installed between the parabolic mirror 47 and the concave mirror 48 and transmits infrared light.

  The beam splitter 1 includes a semitransparent plate 3 having a semitransparent material vapor deposition surface on one side of an infrared transmissive material, a compensation plate 2 having the same material and shape as the semitransparent plate 3, and a semitransparent plate holder 5. It is disposed on the plate holder 4 and is a combination of the two. The beam splitter 1 is installed at a predetermined angle with respect to the incident infrared light beam, and moves so that half of the incident light beam is reflected and transmitted to the fixed mirror 46 and the other half is transmitted in the direction of the infrared optical axis. Guide to mirror 45. The reflected light from both mirrors is again synthesized by the beam splitter 1, transmitted through the sample 50, detected by the detector 49, and the resulting interference pattern is Fourier transformed in a data processing unit (not shown). Thus, a spectrum is obtained.

  FIG. 2 shows an outline of the configuration of the beam splitter used in the Fourier transform infrared spectrometer according to the embodiment of the present invention. (A) is a front view, (b) is a right side view (AA cross-sectional view), and (c) is a top view (BB cross-sectional view). FIG. 3 shows a component diagram in the embodiment of the present invention. (A) shows the presser plate and (b) shows the guide plate.

  The procedure for assembling the beam splitter 1 is shown below. First, after the compensation plate 2 is inserted into the compensation plate holder 4, the guide plate 8 having the guide hole 8b (see FIG. 3B) is installed in the guide portion 8a, and then the ball 9a is inserted into the guide hole 8b. Further, the holding plate 7 is set and fastened with screws 11. By this fastening, the head of the ball 9a protruding outside from the surface of the guide plate 8 is pressed against the contact portion 2a of the compensation plate 2 by the spring portion 7a of the press plate 7 (see FIG. 3A), whereby the compensation plate 2 Is fixed to the compensation plate holder 4.

  Next, the compensation plate holder 4 to which the compensation plate 2 is fixed is fixed to the semi-transparent plate holder 5 with the presser foot 6 using the screw 10. After the semi-transparent plate 3 is inserted into the semi-transparent plate holder 5, a guide plate 8c having a guide hole 8b is installed in the guide portion 8a, then a ball 9b is inserted into the guide hole 8b, and a presser plate 7c is set. Fasten with the screw 11a. By this fastening, the semitransparent plate 3 is pressed against the semitransparent plate holder 5 by pressing the head of the ball 9b protruding from the surface of the guide plate 8c to the contact portion 2a of the compensation plate 2 by the spring portion 7b of the presser plate 7c. Fixed. Thus, the assembly of the beam splitter 1 is completed.

  The beam splitter 1 is set in a beam splitter holder 15 installed in a Fourier transform infrared spectrometer 20. The beam splitter holder 15 includes a frame 16, guides 17 and 18, and a lower guide 19.

  Further, in order to reduce or eliminate interference between the semi-transparent plate and the compensation plate due to surface accuracy, the relative angular positional relationship between the semi-transparent plate 3 and the compensation plate 2 is changed. FIG. 4 shows an adjustment state of the beam splitter 1 in the embodiment of the present invention.

  As shown in FIG. 4, the adjustment procedure is as follows. When the screw 10 is gradually loosened while the beam splitter 1 is set in the beam splitter holder 15, the translucent plate 3 loaded via the ball 9b by the spring portion 7b is compensated. It moves to the left in the figure together with the plate holder 4, and the bending of the spring portion 7b is gradually released, and the load force by the spring becomes zero at a certain point. When the screw 10 is further loosened, the compensator plate holder 4 is completely released from the force in the optical axis direction, and can be rotated via an inlay portion (shown) having a high-precision fitting relationship with the semi-transparent plate holder 5.

  The Fourier transform infrared spectroscopic device 20 is operated, while checking the interference state from the spectrum, while changing the angular position of the compensation plate holder 4, the optimum angular position for improving the interference state is specified, and the compensation plate holder 4 Is fixed to the semi-transparent plate holder 5 using the screw 10 with the presser foot 6, and the adjustment is completed.

  In addition, the screw 10 is arrange | positioned in the upper part in order to avoid the interference at the time of an operation | work with the other optical components arrange | positioned around. Further, in consideration of workability, the screw 10 may be a bolt using a spanner or a knurled screw that can be turned by hand. Further, in order to minimize the influence of the positional deviation caused by the distortion of each part due to thermal change on the measurement result, it is desirable to make the structural part from the same material such as aluminum. In FIG. 1 to FIG. 6, the same reference numerals represent the same thing and have the same function.

1, 21 Beam splitter 2, 22 Compensation plate 2a Contact portion 3, 23 Semi-transmission plate 4, 24 Compensation plate holder 5, 25 Semi-transmission plate holder 6 Presser plate 7, 7c, 27 Press plate 7a, 7b, 27a Spring unit 8 8c, 28 Guide plate 8a, 28a Guide portion 8b, 28b Guide hole 9a, 9b, 29a, 29b Ball 10 Screw 11, 11a, 31, 31a Screw 15, 55 Beam splitter holder 16, 56 Frame 17, 18, 57, 58 guide 19, 59 under guide 20, 40 Fourier transform infrared spectroscope 36 flat head screw 41, 61 light source 42, 48, 62, 68 concave mirror 43, 47, 63, 67 parabolic mirror 44, 64 entrance slit 45, 65 Moving mirrors 46, 66 Fixed mirrors 49, 69 Detectors 50, 70 Samples 51, 53, 71, 73 Optical systems 52, 72 Interference mechanism

Claims (1)

  A light source that emits infrared light that irradiates the sample, an optical system that converts infrared light from the light source into parallel light, a beam splitter that modulates infrared light that has passed through the optical system, and the beam splitter. In the Fourier transform infrared spectroscopic device, the fixed Fourier mirror and the movable mirror that reflect the reflected and transmitted infrared light, and the detection device that measures the infrared light that has passed through the beam splitter, the Fourier transform type In a state where the beam splitter is installed in an infrared spectroscopic device, a fixing tool is disposed at a position where the semi-transparent plate and the compensation plate constituting the beam splitter can be fixed and released. The structure is such that the relative angular position of the compensation plate with respect to the semi-transparent plate can be changed and the changed angular position can be determined by releasing the gap between the transparent plate and the compensation plate. Fourier transform infrared spectrometer to.

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