JP2005331419A - Microscopic spectral measuring instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microscopic spectral measuring instrument capable of simply measuring a transmitted and/or reflected spectrum and a Raman and/or fluorescence spectrum with respect to the specific minute part of a sample with good positional precision. <P>SOLUTION: The microscopic spectral measuring instrument includes a first optical system and a second optical system. The first optical system is constituted so as to allow first light to be incident on a measuring part to measure at least one spectrum (A) selected from the transmitted spectrum and reflected spectrum of the measuring part and the second optical system is constituted so as to allow second light to be incident on the measuring part to measure at least one spectrum (B) selected from the Raman spectrum and fluorescence spectrum of the measuring part. The first and second optical systems hold a plurality of optical elements in common and the light paths of the first and second optical systems are an overlapped part and contain a part where first and second lights advance in mutually reverse directions. The first and second optical systems can be changed over. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a microspectrophotometer.

Conventionally, an apparatus for measuring a transmission and reflection spectrum of a specific minute region of a sample has been proposed (for example, Patent Document 1). An apparatus for measuring a Raman spectrum of a specific minute region of a sample has also been proposed (for example, Patent Document 2).
JP 2000-356588 A JP 2001-215193 A

  When a transmission / reflection spectrum and a Raman spectrum are measured using a conventional apparatus, it is necessary to measure each with a separate apparatus. However, when measuring an object with a different composition or crystallinity for each minute area, if the part where the transmission / reflection spectrum is measured and the part where the Raman spectrum is measured are different, There was a problem that the correlation became unknown. On the other hand, when trying to measure the transmission / reflection spectrum and the Raman spectrum with one apparatus, it is necessary to use a large number of optical elements, which causes a problem that the apparatus becomes complicated and expensive.

  In view of such circumstances, the present invention provides a microspectrophotometer that can easily and accurately measure a transmission spectrum and / or a reflection spectrum and a Raman spectrum and / or a fluorescence spectrum for a specific minute portion of a sample. One of the purposes is to do.

  As a result of studies to achieve the above object, the present inventors have found that the optical path of an optical system for measuring a transmission spectrum and an optical system for measuring a Raman / fluorescence spectrum are substantially reversed. The present inventors have found that the above-described object can be achieved by configuring in a direction. The present invention is based on this new finding.

  That is, the microspectroscopic light measuring apparatus of the present invention is a microscopic spectroscopic light measuring apparatus that performs spectroscopic measurement of the measurement part using a part of a sample as a measurement part, and includes a first optical system and a second optical system, The first optical system is an optical system for measuring at least one spectrum (A) selected from a transmission spectrum of the measurement portion and a reflection spectrum of the measurement portion by causing the first light to enter the measurement portion. The second optical system measures at least one spectrum (B) selected from a Raman spectrum of the measurement portion and a fluorescence spectrum of the measurement portion by causing the second light to enter the measurement portion. The first and second optical systems share a plurality of optical elements, and the optical path of the first optical system and the optical path of the second optical system overlap each other. Part A is and includes a portion between the first light and the second light travels in opposite directions. The first optical system and the second optical system can be switched. That is, the optical system to be used can be easily switched according to the spectrum to be measured.

  According to the apparatus of the present invention, a transmission spectrum and / or a reflection spectrum and a Raman spectrum and / or a fluorescence spectrum can be easily and accurately measured for a specific part of a sample. According to the apparatus of the present invention, it is possible to evaluate a minute region having a diameter of 5 μm or less. This makes it possible to accurately evaluate the physical properties of samples having different compositions and crystallinity for each minute region. Further, according to the apparatus of the present invention, after measuring the transmission spectrum of a part of the sample to obtain information on the absorption peak, the Raman spectrum and / or the fluorescence spectrum is measured by irradiating light according to the absorption peak. can do. Therefore, the Raman spectrum and / or fluorescence spectrum can be measured efficiently.

  Embodiments of the present invention will be described below. The microspectroscopic measurement apparatus of the present invention is an apparatus for performing spectroscopic measurement of a measurement part using a part of a sample as a measurement part.

  The apparatus of the present invention includes a first optical system and a second optical system. The first optical system is an optical system for measuring at least one spectrum (A) selected from the transmission spectrum of the measurement portion and the reflection spectrum of the measurement portion by causing the first light to enter the measurement portion. The second optical system is an optical system for measuring at least one spectrum (B) selected from the Raman spectrum of the measurement portion and the fluorescence spectrum of the measurement portion by causing the second light to enter the measurement portion. The first and second optical systems share a plurality of optical elements, and the optical path of the first optical system and the optical path of the second optical system are overlapping portions and the first light And a portion where the second light travels in opposite directions. The first optical system and the second optical system can be switched. That is, the first light that travels through the first optical system and the second light that travels through the second optical system travel on the same optical path in opposite directions in part of the optical path.

  In the apparatus according to the present invention, the first light is incident on the measurement portion from one of the samples to measure the transmission spectrum of the measurement portion, and the second light is incident on the measurement portion from the other side opposite to the one. It is preferable to measure the spectrum (B).

  In the apparatus of the present invention, it is preferable that the first optical system further includes an optical element for measuring the reflection spectrum of the measurement portion by causing the first light to enter the measurement portion from the other side. According to this configuration, the transmission spectrum and reflection spectrum of the measurement part can be easily measured.

  In the apparatus of the present invention, it is preferable that the first and second optical systems share the first and second mirrors. In this case, in the first optical system, the first mirror reflects the first light in the direction of the sample, and the second mirror transmits the first light transmitted through the sample in the direction of the first photodetector. In the second optical system, the second mirror reflects the second light in the direction of the sample, and the first mirror reflects the light (fluorescence or Raman light) emitted from the sample in the second optical system. Reflecting in the direction of the photodetector is preferred. According to this configuration, the spectra (A) and (B) can be measured with a small number of optical elements. Furthermore, in this case, it is preferable to further include a motor that rotates the second mirror in order to switch between the measurement of the spectrum (A) and the measurement of the spectrum (B). Thereby, the measurement of the spectrum (A) and the measurement of the spectrum (B) can be easily switched without changing the measurement location.

  In the apparatus of the present invention, the first and second optical systems may share one spectrometer. The spectroscope functions as a spectroscope that splits the first light and a spectroscope that splits at least one light selected from Raman scattered light and fluorescence generated when the second light is incident on the measurement portion. To do. By using such a spectroscope, the apparatus can be simplified.

  The shared spectrometer is preferably a differential dispersion type double spectrometer. The differential dispersion type double spectrometer is obtained by arranging and connecting two spectrometers in series. When a single spectroscope is used, color unevenness of the first light occurs due to wavelength dispersion, but such color unevenness can be suppressed by using a differential dispersion type double spectroscope. Therefore, in the apparatus of the present invention for measuring the spectrum (A) and the spectrum (B), it is preferable to use a differential dispersion type double spectrometer.

  The shared spectrometer includes an exit slit from which the first light exits, the first optical system includes a field stop, and the position of the measurement portion is adjusted using the exit slit and the field stop. Also good. The field stop is disposed in the optical path after the first light is transmitted or reflected by the sample. By causing the exit slit to function as a field stop for light before entering the sample, it is possible to suppress the incidence of light from other than the measurement region, and to accurately measure the transmission spectrum of the sample having high absorbance.

  Below, an example of the apparatus of this invention is demonstrated. An example of the microspectroscopic light measurement apparatus of the present invention (hereinafter referred to as apparatus 100) is shown in FIGS. FIG. 1 shows an optical path for measuring a transmission spectrum, FIG. 3 shows an optical path for measuring a reflection spectrum, and FIGS. 4 and 5 show optical paths for measuring a Raman spectrum or a fluorescence spectrum. Show. 1 and 3 to 5 also show some top views.

(Measurement of transmission spectrum)
In the apparatus 100 of FIG. 1, the 1st light 11 is radiate | emitted from a light source. The first light 11 is light having at least a part of the wavelength range from the ultraviolet region to the near infrared region. The light source is not particularly limited as long as it is a light source that emits light in such a wavelength range. In the apparatus 100, a halogen lamp 12 and a deuterium lamp 13 are used as light sources. When the halogen lamp 12 is used, the mirror 14 is excluded from the optical path. When the deuterium lamp 13 is used, a mirror 14 is disposed on the optical path. The light emitted from the deuterium lamp 13 enters the concave mirror 15 through the mirror 14.

  The first light 11 is reflected by the concave mirror 15, passes through the chopper 16, and is introduced into the spectroscope 17. The chopper 16 is for modulating only the first light 11, and it is possible to remove the influence of light other than the first light 11, electrical noise, and the like. When the apparatus 100 is used in an environment where light is sufficiently shielded, the chopper 16 is usually unnecessary. However, when an infrared detector using PbS or the like is used, it is preferable to use the chopper 16 in order to remove thermal noise.

  The spectroscope 17 is a spectroscope shared by the first optical system and the second optical system. The spectroscope 17 is a differential dispersion type double spectroscope. In the shared spectrometer, stray light included in the first light to be monochromated causes a reduction in the accuracy of transmission spectrum measurement for a sample having strong light absorption. It is desirable to use a differential dispersion type double spectrometer having a high stray light removal rate. A spectroscope such as a high dispersion spectroscope may be used as the spectroscope 17. An example of the configuration when the spectrometer 17 is a differential dispersion type double spectrometer is shown in FIG. The spectroscope 17 of FIG. 2 includes an entrance slit 17a, a spherical mirror 17b, a plane mirror 17c, a grating 17d, an aberration correction mirror 17e, a spherical mirror 17f, a grating 17g, a plane mirror 17h, an aberration correction mirror 17i, and an exit slit 17j. As shown in FIG. 2, the spectroscope 17 has a structure in which two spectroscopes are arranged in line symmetry. By using such a differential dispersion type double spectrometer, stray light and color unevenness can be reduced.

  From the exit slit 17j of the spectroscope 17, the first light 11 that has become monochromatic light is emitted. The first light 11 passes through a polarizer 18 and enters a mirror (first mirror) 19.

  The mirror 19 reflects the first light 11 in the direction of the sample 101 arranged on the sample stage 30. The first light 11 is condensed and imaged on a measurement portion which is a part of the sample 101 by the cassegrain mirror 20. The first light 11 transmitted through the measurement portion must be imaged at the position of the field stop 22 by the cassegrain mirror 21. The position, size, and image formation of the field of view to be measured are confirmed and adjusted visually with the eyepiece for visual observation of the trinocular tube 23. Note that the first light 11 at this time is visible light. If the position of the field of view and imaging are not appropriate, the position of the sample stage 30 on which the sample is placed and the position of the cassegrain mirror 20 are adjusted in the three-dimensional direction. The field size is determined by the opening of the field stop 22 and the exit slit 17j. When the position and size of the field of view are appropriate, the prism in the trinocular tube 23 is removed, and the first light 11 is guided upward. The first light 11 passes through the filter 24 and is then collected by the mirror (second mirror) 25 on the photodetector. The filter 24 is arranged to remove second-order diffracted light that could not be removed by the spectroscope 17. The mirror 25 is a concave mirror or a parabolic mirror. The mirror 25 is rotated by a motor (not shown), and the rotation is usually controlled by a computer. Of the optical elements described below, a movable optical element is controlled by a motor, a computer, and the like, similarly to the mirror 25.

  The photodetector only needs to be able to detect the amount of light of the first light 11. For example, a photomultiplier tube, a photodiode, an infrared detector, or the like can be used. These are selected according to the wavelength and intensity of the light to be measured. In the example of FIG. 1, a photodetector 26 and a photodetector 27 are used as the photodetector. Specifically, the photodetector 26 is a photomultiplier tube, and the photodetector 27 is a PbS photoconductive element.

  In the apparatus 100, by changing the wavelength of the monochromatic light emitted from the spectroscope 17, it is possible to accurately measure the transmission spectrum in a wide wavelength range. Further, in the apparatus 100, only two mirrors are used in the optical path between the spectroscope 17 and the photodetector, except for the cassegrain mirror. Therefore, there is little reduction in the amount of light due to reflection at the mirror, and distortion of the field of view due to the surface roughness of the mirror and the aberration of the concave mirror can be minimized. Since the light amount of the deuterium lamp 13 is generally low, it is particularly important to suppress the reduction of the light amount. In general, the transmission spectrum is a preferred measurement method because it is easier to analyze and interpret the spectrum than the reflection spectrum described below. However, in the transmission spectrum measurement, it is necessary to accurately measure even a high absorbance. Therefore, in the optical path design, it is important to devise the optical path design such that the arrangement of optical elements and the like giving priority to the measurement of the transmission spectrum and the number of mirrors are reduced to facilitate the adjustment.

(Measurement of reflection spectrum)
An example of a method for measuring the reflection spectrum is shown in FIG. When measuring the reflection spectrum, the mirror 31 and the mirror 32 are arranged on the optical path shown in FIG. Although the mirror 32 is a total reflection type, the size and position are set so as to cover only half of the inside of the microscope tube. The first light 11 emitted from the spectroscope 17 and transmitted through the polarizer 18 is reflected by the mirror 31, reflected by the concave mirror 33, and collected at the position of the field stop 34. The spherical aberration caused by the concave mirror 33 can be eliminated by the field stop 34. The field stop 34 exists at a position conjugate with the field stop 22 (equal lens barrel length). The first light 11 transmitted through the field stop 34 is reflected in the direction of the sample 101 by the mirror 32, and is condensed on the measurement location of the sample 101 by the cassegrain mirror 21.

  The first light 11 reflected by the sample 101 reaches the position of the mirror 32 through the cassegrain mirror 21, but the mirror 32 does not cover the entire interior of the lens barrel, so that the space in the lens barrel where this mirror does not exist. Then, the light enters the field stop 22 and the amount of light is measured in the same manner as the transmission spectrum. In this way, the reflection spectrum is measured. In the apparatus 100, the optical path can be switched simply by inserting the two mirrors 31 and 32 into the optical path for measuring the transmission spectrum, and the reflection spectrum can be measured easily. As in the transmission spectrum measurement, the field size, position, and image formation are optimized by adjusting the field stops 22 and 34 and the sample stage 30.

(Measurement of fluorescence spectrum)
An example of a fluorescence spectrum measurement method is shown in FIG. The Raman spectrum can also be measured by the same method as the fluorescence spectrum.

  The second light 41 emitted from the light source is reflected by the concave mirror 42 and enters the spectroscope 44 via the chopper 43. The second light 41 may be light including a wavelength region that can excite fluorescence (or Raman scattered light). The light source may be any light source that emits such light. For example, a high-intensity xenon lamp or a laser device can be used. If a laser device is used, the spectroscope 44 can be omitted. The apparatus 100 uses a xenon lamp 45 as a light source. By combining a lamp such as a xenon lamp and a spectroscope, the sample can be excited at an arbitrary wavelength. Similar to the chopper 16, the chopper 43 is arranged to remove the influence of light other than the light from the light source, and may be omitted depending on the measurement conditions. The spectroscope 44 is not particularly limited, and various spectroscopes can be used. However, a low dispersion type spectroscope is preferable in that monochromatic light with high luminance can be obtained.

  The second light 41 that has become monochromatic light by the spectroscope 44 passes through the polarizer 46, is reflected by the mirror 25, and is collected at the field stop 22. The second light 41 that has passed through the field stop 22 is incident on a predetermined measurement portion of the sample 101, that is, a portion where the transmission / reflection spectrum is measured, via the cassegrain mirror 21. The sample 101 irradiated with the second light 41 generates fluorescence (or Raman scattered light). The xenon lamp 45, the concave mirror 42, the spectroscope 44, and the mirror 25 need to be arranged so that the second light 41 is incident on the portion where the transmission / reflection spectrum is measured. Since the position, size, and image formation of the measurement field are adjusted by the transmission or reflection spectrum measurement mode, it is only necessary to move the mirror 25 to a predetermined position. According to the apparatus of the present invention, the positional deviation between the measurement part where the transmission / reflection spectrum is measured and the measurement part where the fluorescence (or Raman scattered light) is measured can be set to several microns or less.

  In FIG. 4, the fluorescence (or Raman scattered light) generated in the sample 101 travels in the same optical path as the optical path at the time of reflection spectrum measurement and enters the spectroscope 17 in the reverse direction. In addition, you may measure fluorescence using the same optical path as the time of measurement of a transmission spectrum. In general, non-resonant Raman scattered light is often obtained with such an optical system. The optical path in that case is shown in FIG. In FIG. 5, the fluorescence (or Raman scattered light) generated in the sample 101 travels in the reverse direction along the same optical path as the transmission spectrum measurement and enters the spectroscope 17. Which optical path is used can be switched by the mirror 31 and the mirror 32. The fluorescence (or Raman scattered light) incident from one slit of the spectroscope 17 is split and emitted from the other slit of the spectroscope 17. At the time of fluorescence spectrum measurement, the exit slit 17j of the spectroscope 17 becomes a light incident side slit.

  A light detector 47 is arranged on the light emission side of the spectroscope 17, and the fluorescence emitted from the spectroscope 17 enters the light detector 47. In this way, a fluorescence spectrum or a Raman spectrum can be measured. In consideration of sensitivity, it is preferable to use a photomultiplier tube as the photo detector 47. However, in consideration of the excitation wavelength of the sample and the wavelength range in which fluorescence appears, a detector based on another principle, such as a photodiode, is used. It may be used. In addition, since fluorescence and Raman scattered light generally have different wavelengths from excitation light, excitation light and fluorescence (and Raman scattered light) can be separated by a spectroscope. Therefore, when measuring these spectra, the exit slit 17j and the field stop 34 are made wider than when the transmission / reflection spectrum is measured, and as much fluorescence or Raman light as possible is sent to the spectroscope 17 and further to the light detection. It may be incident on the instrument 47.

  As described above, the apparatus 100 includes optical elements such as the concave mirror 15, the spectroscope 17, the mirror 19, the cassegrain mirrors 20 and 21, the field stop 22, and the mirror 25 as the first optical system for measuring the transmission spectrum. . When measuring a reflection spectrum, the first optical system includes optical elements such as a mirror 31, a mirror 32, a concave mirror 33, and a field stop 34 in addition to the above optical elements. In addition, the apparatus 100 includes, as a second optical system for measuring a fluorescence spectrum or a Raman spectrum, a concave mirror 42, a spectroscope 44, a mirror 25, a field stop 22, cassegrain mirrors 20 and 21, a mirror 19, a spectroscope 17, and the like. Is provided. When an optical path for measuring the reflection spectrum is used, a mirror 31, a mirror 32, a concave mirror 33, and a field stop 34 are used in place of the cassegrain mirror 20 and the mirror 19. Thus, the first optical system and the second optical system share at least the spectroscope 17, the cassegrain mirror 21, the field stop 22, and the mirror 25.

  The optical path of the first optical system and the optical path of the second optical system partially overlap in the opposite direction. For example, the light traveling on the optical path in FIG. 1 and the light traveling on the optical path in FIG. 5 travel in opposite directions on the optical path from the spectroscope 17 to the mirror 25. Similarly, the light traveling on the optical path in FIG. 3 and the light traveling on the optical path in FIG. 4 travel in opposite directions on the optical path from the spectroscope 17 to the mirror 25. In this configuration, the optical system for measuring the spectrum (A) and the optical system for measuring the spectrum (B) share optical elements such as a spectroscope and a mirror, so that the number of optical elements is reduced. Can do. Further, the first optical system and the second optical system are set so as to form an image at the same position (the position of the field stop 22 and the measurement portion). In this configuration, the measurement of the spectrum (A) and the measurement of the spectrum (B) can be easily switched by moving only the mirrors 25 and 31, the mirror 32, and the photodetector 47, and the spectrum of the same part (A) and spectrum (B) can be easily measured.

  1 to 5 is an example, and the present invention is not limited to this. The optical elements used in the apparatus may be omitted, added, or changed within a range where the effects of the present invention can be obtained. For example, a lens may be used instead of a cassegrain mirror. Further, the polarizers 18 and 46 may be omitted. However, since these polarizers can be used to measure in the polarization mode, it is possible to evaluate the degree of orientation of anisotropic substances. For example, the degree of orientation of carbon nanotubes and polymers can be evaluated for substances and polymer films in which nanomaterials having anisotropic shapes such as carbon nanotubes are aggregated in the order of microns.

  The microspectrophotometer of the present invention is effective for analyzing various substances, and particularly effective for analyzing substances having different physical properties such as composition and crystallinity for each minute region and analyzing minute substances. For example, it is useful for analysis of polycrystals, microcrystals, etc., and evaluation of physical properties of semiconductor devices having a micron order size. Further, according to the apparatus of the present invention, after measuring the transmission spectrum of the object to be measured to obtain information about the absorption peak of the substance, it is possible to excite the absorption peak and measure the fluorescence spectrum. . Therefore, according to the apparatus of the present invention, the fluorescence characteristics of a substance can be efficiently evaluated. In addition, by measuring Raman scattering, it is possible to evaluate the chemical composition, crystal structure, and orientation direction of a minute region.

It is a figure which shows typically the method of measuring a transmission spectrum in an example of the microspectroscopic light measuring apparatus of this invention. It is a figure which shows typically the structure of an example of a difference dispersion type | mold double spectrometer. It is a figure which shows typically the method of measuring a reflection spectrum in an example of the microspectroscopic light measuring apparatus of this invention. It is a figure which shows typically the method of measuring a fluorescence spectrum in an example of the microspectroscopic light measuring apparatus of this invention. It is a figure which shows typically the other method of measuring a fluorescence spectrum in an example of the microspectroscopic light measuring apparatus of this invention.

Explanation of symbols

11 First light 12 Halogen lamp 13 Deuterium lamp 14, 31, 32 Mirror 15, 33, 42 Concave mirror 16, 43 Chopper 17 Spectroscope (shared spectrometer)
18, 46 Polarizer 19 Mirror (first mirror)
20, 21 Cassegrain mirror 22, 34 Field stop 23 Trinocular tube 24 Filter 25 Mirror (second mirror)
26, 27 photodetector (first photodetector)
30 Sample stage 41 Second light 44 Spectrometer 45 Xenon lamp 47 Photo detector (second photo detector)
100 apparatus (microspectrophotometer)
101 samples

Claims (8)

A microspectroscopic measurement device that performs spectroscopic measurement of the measurement part using a part of the sample as a measurement part,
Including a first optical system and a second optical system;
The first optical system is an optical system for measuring at least one spectrum (A) selected from a transmission spectrum of the measurement portion and a reflection spectrum of the measurement portion by causing the first light to enter the measurement portion. System,
The second optical system is an optical system for measuring at least one spectrum (B) selected from the Raman spectrum of the measurement portion and the fluorescence spectrum of the measurement portion by causing the second light to enter the measurement portion. System,
The first and second optical systems share a plurality of optical elements,
The optical path of the first optical system and the optical path of the second optical system include an overlapping part and a part in which the first light and the second light travel in opposite directions. ,
A microspectroscopic light measurement apparatus capable of switching between the first optical system and the second optical system.   The first light is incident from one of the samples to the measurement portion to measure the transmission spectrum of the measurement portion, and the second light is incident on the measurement portion from the other side opposite to the one. 2. The microspectroscopic measurement apparatus according to claim 1, which measures the spectrum (B).   3. The microspectroscopic measurement apparatus according to claim 2, wherein the first optical system includes an optical element for measuring the reflection spectrum of the measurement portion by causing the first light to enter the measurement portion from the other side. 4. The first and second optical systems share first and second mirrors;
In the first optical system, the first mirror reflects the first light toward the sample, and the second mirror detects the first light transmitted through the sample as a first light detection. Reflected in the direction of the vessel,
In the second optical system, the second mirror reflects the second light in the direction of the sample, and the first mirror directs light emitted from the sample in the direction of the second photodetector. The microspectroscopic light measuring device according to claim 1 which reflects.   The microspectroscopic measurement apparatus according to claim 4, further comprising a motor that rotates the second mirror to switch between the measurement of the spectrum (A) and the measurement of the spectrum (B). The first and second optical systems share one spectrometer;
The spectroscope is a spectroscope that splits the first light, and a spectroscope that splits at least one light selected from Raman scattered light and fluorescence generated when the second light is incident on the measurement portion. The microspectrophotometer according to any one of claims 1 to 5, which functions as a vessel.   The microspectroscopic measurement apparatus according to claim 6, wherein the spectrometer is a differential dispersion type double spectrometer.   The spectroscope includes an exit slit from which the first light exits, the first optical system includes a field stop, and the position of the measurement portion is adjusted using the exit slit and the field stop. 6. The microspectroscopic light measuring apparatus according to 6.