JP2006258522A - Infrared microscope - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance measuring efficiency by improving the complication of measurement produced in the simultaneous use of a plurality of dewers including the whole replacement of the dewers or the addition of a light path switching means performed heretofore in a case requiring a plurality of measurements using a plurality of detector elements different in characteristics, the complication of an apparatus and the scaling-up of the apparatus. <P>SOLUTION: Two detector elements, that is, a P detector element 13P and an S detector element 13S respectively different in optical characteristics are mounted on one dewer 12A and an aperture 9 and a three-dimensional stage 6 cooperating to be subjected to reciprocating movement are provided and reciporcally moved to select either one of the P detector element 13P and the S detector element 13S to use it. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an infrared microscope that performs microspectroscopy of a sample with light in the infrared wavelength region.

  An infrared microscope is a device that performs microspectroscopic light in the infrared wavelength region, and is designed to condense an infrared light beam onto a minute area so as to be suitable for spectroscopy of a minute measurement sample. Although the normal magnification is 20 to 30 times, in recent years, with the increase in sensitivity of a Fourier transform infrared spectrometer (hereinafter referred to as FTIR), a microscope having a spatial resolution of about 10 μm combining FTIR and an infrared microscope. The system has been put into practical use. (For example, refer to Patent Document 1). Infrared microscopes can perform nondestructive analysis at room temperature and atmospheric pressure, so the range of samples that can be measured is wide, foreign materials / defects in materials, composition / structure / crystallinity of composite materials, and anisotropy of molecules and crystals It is used for research on biological tissues, fine particles, etc. The basic principle is shown below.

  Infrared light from a Michelson interferometer in the FTIR is directed to an infrared microscope. The optical path of the infrared light is controlled through a front-end optical system composed of a reflecting mirror, a translucent mirror, a prism, and a condenser using a concave mirror and is focused to about 1 mm. (Abbreviated) is applied, and the transmitted light of the sample is extracted and focused through a reflective objective mirror using a concave mirror. In order to detect stray light generated from other than the sample and detect only the light that has passed through the sample, a diaphragm (hereinafter referred to as an aperture) is placed in the imaging area behind the reflective objective mirror. The optical path of the latter stage optical system composed of semi-transparent mirrors and prisms is controlled and focused again, irradiated to a small area detector element at the confocal position of the aperture, converted into an electrical signal, and further subjected to Fourier transform It becomes an infrared spectrum.

  As the detector element, a semiconductor detector (for example, MCT detector, InGaAs crystal, etc.) is used. Since a semiconductor detector is generally required to be kept at a low temperature during measurement for high sensitivity measurement, a coolant such as liquid nitrogen is used. Alternatively, a low-temperature surface is provided on a part of the surface of a cooling device such as a thermos containing refrigerant (hereinafter referred to as “Dewar”), and the detector element is attached to a detector holder that is in close contact with the low-temperature surface to keep the detector element at a low temperature. use. In addition, not only the transmitted light of the sample but also reflected light from the sample surface may be used as the infrared light that irradiates the detector element.

  In this case, the infrared light from the Michelson interferometer is guided from the aperture direction to the sample surface via the reflecting objective by a semi-transparent mirror provided between the aperture and the reflecting objective, and the reflected light from the sample surface is guided. The light is again incident on the aperture in the imaging unit via the reflective objective mirror and the semi-transparent mirror. The optical path below the aperture is the same as in the case of transmitted light measurement. In addition, for visual recognition of the optical path and the sample image, a visible light source is generally provided at the entrance of the optical path of the infrared microscope so as to obtain the same optical path as the infrared light from the Michelson interferometer. It is used by switching to light. In this case, the sample image is visually confirmed by moving an optical path changing mirror provided behind the aperture and changing the direction of light directed toward the detector element to guide it to an optical microscope or a CCD screen via the optical microscope. Is done by.

  Hereinafter, the structure and operation of a conventional infrared microscope will be described with reference to FIG. The infrared light beam L emitted from the FTIR 1 is reflected by the switching mirror 2 and converged via the front optical system 3 composed of a reflecting mirror, a semitransparent mirror, a prism, and the like, a mirror 4, and a condenser 5 using a concave mirror. Then, an area of about 1 mm of the sample 7 on the three-dimensional stage 6 is irradiated. The three-dimensional stage 6 has a structure capable of coarsely and finely moving the sample 7 in the XYZ3 directions. The light beam L transmitted through the sample 7 is taken out upward in the figure through the reflecting objective mirror 8 and focused at the position of the aperture 9.

  Further, the light beam L is reflected by the switching mirror 10, focused by a subsequent optical system 11 composed of a reflecting mirror, a semitransparent mirror, a prism, and the like, and placed on the detector element 13 placed at the confocal position of the aperture 9. Form an image. The detector element 13 is cooled by a dewar 12. Reference numeral 12W denotes a side wall provided for protecting the detector element 13. An infrared spectrum is obtained by Fourier-transforming the electrical signal of the sample 7 obtained by the detector element 13.

  The above explanation is about the case where the transmitted light of the sample 7 is analyzed, but the optical path is changed in the front optical system 3, and the light from the switching mirror 2 is guided to the middle between the reflecting objective mirror 8 and the aperture 9. Then, a semi-transparent mirror (not shown) is caused to enter the surface of the sample 7 via the reflecting objective mirror 8, and the reflected light from the sample 7 is again incident on the aperture 9 via the reflecting objective mirror 8 to reflect the reflected light of the sample 7. Reflected light analysis can be performed by forming an image on the detector element 13. Also in the reflected light analysis, the path of the light beam L after the aperture 9 involved in the present invention is the same as in the case of the transmitted light analysis, so that further description of the reflected light analysis is omitted.

  Since the light beam L from the FTIR 1 is infrared light and cannot be visually recognized, a visible light source 14 is provided for visual recognition of the optical path and the image formation state. Visible light from the visible light source 14 is formed into a shape equivalent to the infrared light from the FTIR 1 by the condenser lens 15 and travels in the direction of the preceding optical system 3 by moving the switching mirror 2 from the optical path. Accordingly, the optical path and the imaging state can be confirmed. The switching mirror 10 is moved from the optical path, and the visible light traveling from the aperture 9 is guided to a CCD screen (not shown) or the like through the optical microscope OP or the optical microscope OP, so that an optical microscopic image of the sample 7 is visually recognized. Or you can record.

  FIGS. 5B and 5C respectively show the aperture portion total imaging range 16, the aperture opening 17, the sample image center 18, and the detector portion total imaging range at the position of the aperture 9 and the position of the detector element 13. 16A schematically shows the mutual positional relationship among 16A, the detector element 13, the aperture opening image 17A, and the detector portion sample image center 18A. Aperture full image forming range 16 and detector full image forming range 16A indicate the limits of the image forming range of the image of the three-dimensional stage position at the position of aperture 9 and the position of detector element 13, and the size and The position is determined by the position of the condenser 5 and the reflecting objective mirror 8 and the magnification relationship, and an image of the sample 7 within this range can be formed at the position of the aperture 9 and the detector element 13 at the confocal point. The sample image center 18 and the detector part sample image center 18A schematically show the center position of the spectral target portion of the sample 7, and the desired sample image center 18 is moved to the aperture opening 17 and thus the aperture opening by the movement of the three-dimensional stage 6. It can be selected in the center of the image 17A. The size of the aperture opening 17 is usually selected so that the size of the aperture opening image 17A is slightly smaller than the detector element 13.

JP 2000-121553 A (page 1-6)

  The structure and operation of a conventional infrared microscope are as described above, but there is a problem in the use of a plurality of detector elements 13 in this structure. In general, a particular detector element 13 does not satisfy all of the wavelength region and sensitivity at the same time. As an example, since the MCT detector has a characteristic that the sensitivity of a wide wavelength region is low, several types of detector elements 13 having different characteristic ranges are exchanged or switched depending on the wavelength region to be measured and the required sensitivity. Had to be used.

  However, in the conventional structure, measurement is performed using both detector elements 13 having different characteristics, for example, a detector element 13 having a narrow wavelength sensitivity range but a high sensitivity, and a detector element 13 having a low sensitivity but a wide wavelength sensitivity range. The procedure was complicated and the measurement efficiency was reduced. That is, in the conventional structure, only one detector element 13 is attached to the dewar 12, and the dewar 12 has different characteristics for measurement in a characteristic range different from that of the currently installed detector element 13. Replace the dewar 12 with the detector element 13 attached, or simultaneously attach a plurality of dewars 12 with one detector element 13 with different characteristics to the apparatus, and an optical element such as a mirror in the optical path after the aperture 9 Either one of the plurality of dewars 12 is selected by switching the optical path.

  Replacing the entire dewar 12 is complicated, and when a plurality of dewars 12 are used, a plurality of dewars 12 must be installed and an optical path switching means must be added. Even in this case, the measurement efficiency is greatly reduced. If more than two types of measurements are required, the difficulty increases. An object of the present invention is to provide means for solving such problems.

  In order to solve the above-described problems, the infrared microscope provided by the present invention has a sample placed on a stage that is reciprocally movable, and an aperture that guides the irradiation of infrared light to the sample is also reciprocally movable. In an infrared microscope that irradiates a sample with infrared light and injects infrared light from the sample into a detector element of a semiconductor detector to measure the sample, a mechanism is provided for reciprocating the stage and the aperture. A plurality of types of detector elements are provided, and a mechanism capable of selecting any one of the detector elements is provided.

  As an effect of the present invention, by providing a mechanism for interlocking the reciprocation of the stage and the aperture, providing a plurality of types of detector elements, and providing a mechanism for selecting any one of these detector elements, detector elements having different characteristics Replace the entire cooling device (dewar) equipped with one detector element or perform multiple cooling devices (dewars) equipped with detector elements with different characteristics at the same time. In addition, it is possible to easily perform a plurality of measurements using detector elements having different characteristics without adding an optical element such as a mirror to the optical path after the aperture and switching the optical path.

  The infrared microscope provided by the present invention has the following characteristics. The first feature is that a mechanism for interlocking the reciprocation of the stage and the aperture is provided. The second feature is that a plurality of types of detector elements are provided and a mechanism capable of selecting any one of the detector elements is provided. Therefore, the basic configuration of the best mode is an infrared microscope having a mechanism for interlocking the reciprocating motion of the stage and the aperture, and a mechanism for providing a plurality of types of detector elements and selecting any one of the detector elements. .

  This will be described with reference to the illustrated example. 1 and 2 are configuration diagrams of a first embodiment of the present invention. 1 and 2, the structure and operation of the parts having the same reference numerals as those in FIG. 5 are the same as those in FIG. 5. FIG. 1 shows an example of the configuration of the dewar. 1A is a front view of the dewar 12A, and FIG. 1B is a side view. Two detector elements having different wavelength absorption characteristics, a P detector element 13P and an S detector element 13S are mounted on the detector holder 21 and cooled by a dewar 12A. The detector holder 21 is covered with a window plate 22 and a window plate side wall 23 that are transparent to the measurement wavelength for heat insulation and prevention of frost adhesion.

  FIG. 2 is a diagram for explaining a structure in which the sample 7 and the aperture 9 are reciprocated in an interlocking manner. FIG. 2A shows a conceptual diagram of a structure in which the sample 7 and the aperture 9 are reciprocated in an interlocking manner. 2B and 2C show the image formation state on the aperture 9 and the detector element surface D, respectively. Actually, there is an enlargement / reduction relationship according to the magnification of the reflective objective mirror 8 in FIG. The aperture opening 17P shown in FIG. 2 (B) is an aperture opening image 17PA in the P detector element 13P shown in FIG. 2 (C), and the aperture opening 17S shown in FIG. 2 (B) is S shown in FIG. 2 (C). This corresponds to the aperture opening image 17SA at the position of the detector element 13S. That is, in FIG. 2B, the three-dimensional stage 6 is moved to move the sample image center 18P (center image of the sample 7) to the sample image center 18S, and the aperture 9 is moved to move the aperture opening 17P to the aperture opening 17S. As a result, the detector part sample image center 18PA is moved to the detector part sample image center 18SA and the aperture opening image 17PA is moved to the aperture opening image 17SA on the detector element surface D, and the S detector is detected from the P detector element 13P. Switching of incidence to the element 13S can be achieved. However, in FIG. 2 (A), the sample 7 and the aperture 9 are moved in the same direction by the same distance as the distance between the two detector elements, but this figure shows the basic principle. Depending on the magnification of the image of the sample 7 on the P detector element 13P surface or the S detector element 13S surface and the configuration of the optical system from the three-dimensional stage 6 to each detector element, the moving direction and moving distance of the sample 7 and the aperture 9 Therefore, in the actual apparatus, the sample 7 and the aperture 9 need to be reciprocally moved in the direction and distance determined by the structure of the apparatus.

  FIG. 3 shows a second embodiment of the present invention. In FIG. 3, the structure and operation of components having the same reference numerals as those in FIG. 1 or FIG. 5 are the same as those in FIG. 3A is a front view of the dewar 12B, and FIG. 3B is a side view. In the present embodiment, two detector elements, a P detector element 13P and an S detector element 13S are overlapped in the traveling direction of the light beam L and are mounted on a detector holder 21A disposed on the side surface of the dewar 12B. . The structure of the dewar 12B is the same as that of the dewar 12A of FIG. 1 except for the attachment portion of the detector holder 21A.

  In the present embodiment, the infrared light absorbed by the P detector element 13P does not reach the S detector element 13S, so this must be understood when mounting. For example, if the relationship between the absorption intensity α and the wavelength λ of the P detector element 13P and the S detector element 13S is as shown in the graph shown in FIG. Since a part of the light is absorbed by the P detector element 13P, it does not reach the S detector element 13S. Therefore, the S detector element 13S originally absorbs all the light in the range from the wavelength H to the wavelength J, but in the present embodiment, it cannot absorb the light in the hatched triangular range. However, also in this case, the light from the wavelength I to the wavelength J is absorbed as it is by the S detector element 13S, so that optical information different from that of the P detector element 13P can be obtained.

  The present invention is not limited to the above-described embodiments, and various modified embodiments can be given. For example, in the first embodiment, the two detector elements can be arranged in the vertical direction (vertical direction) in the figure. In the first and second embodiments, the number of detector elements may be three or more if necessary. The present invention includes all of these. In each of the above embodiments, the cooling means is described by taking a dewar as an example, but any cooling means such as Peltier cooling or Stirling cooling can be used. Further, the present invention can be applied even when the cooling means is not required, and the present invention is not limited to the cooling means.

  The present invention can be applied to an infrared microscope that performs microspectroscopy of a sample with light in the infrared wavelength region.

FIG. 2 is a structural diagram of a dewar part of the first embodiment of the present invention. Is a detector element switching mechanism of the first embodiment of the present invention. These are dewar part structure diagrams of the second embodiment of the present invention. These are figures which show the example of the relationship between the absorption intensity of a detector element, and a wavelength. FIG. 1 is an overall configuration diagram of a conventional infrared microscope.

Explanation of symbols

1 FTIR
2 Switching mirror 3 Front stage optical system 4 Mirror 5 Condenser 6 3D stage 7 Sample 8 Reflective objective mirror 9 Aperture 10 Switching mirror 11 Rear stage optical system 12, 12A, 12B Dewar 12W Side wall 13 Detector element 13P P detector element 13S S detection Element 14 Visible light source 15 Condensing lens 16 Aperture part full imaging range 16A Detector part full imaging range 17, 17P, 17S Aperture aperture 17A, 17PA, 17SA Aperture aperture image 18, 18P, 18S Sample image center 18A, 18PA , 18SA detector part sample image center 21, 21A detector holder 22 window plate 23 window plate side wall L luminous flux

Claims (2)

  The sample is placed on a stage that can reciprocate, and an aperture that guides the sample to irradiate infrared light is also provided to reciprocate, irradiate the sample with infrared light, and receive infrared light from the sample. Infrared microscope that measures the sample by entering the detector element of the semiconductor detector is provided with a mechanism for interlocking the reciprocation of the stage and the aperture, and a plurality of detector elements, and any one of these detector elements An infrared microscope characterized in that a mechanism capable of selecting is provided.   2. The infrared microscope according to claim 1, wherein at least one of the plurality of types of detector elements is transparent in a region other than the wavelength at which the detector has sensitivity.

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