JP2001174708A - Infrared microscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an infrared microscope which can be used in the most suitable state with a simple optical system in both a transmission mode and a reflection mode. SOLUTION: Infrared rays from a Fourier transform infrared spectrophotometer are made incident on an upper cassegrain 4 through a fixed reflection mirror 10a and reflection mirrors 34, 35, and 33 and are condensed to a diameter of about 1 mm and are transmitted through a sample 13 set on a plane mirror 14 and are reflected by the plane mirror 14. Reflected infrared rays are transmitted through the sample and pass the upper cassegrain 4 of about 15 magnifications and pass reflection mirrors 33 and 38 and are condensed to a small area by reflection mirrors 39, 40, and 41 and are introduced to an MCT detector 11 and are subjected to Fourier transform to become an infrared spectrum. Transmission measurement of the infrared rays-transmissive sample can be performed by reflection measurement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared microscope which performs microspectroscopy of a minute sample in an infrared wavelength region in combination with an infrared spectrophotometer used for qualitative and quantitative determination of a substance.

[0002]

2. Description of the Related Art An infrared microscope is a device that performs microspectroscopy in the infrared wavelength region, and is a microscope designed to focus an infrared light beam on a very small area so as to be suitable for a small sample. Up to 30 times. However, in recent years, microscopes utilizing the enhanced sensitivity of Fourier transform infrared spectroscopy have been developed. This is a microscopic system that combines a Fourier transform infrared spectrophotometer and an infrared microscope, and has a spatial resolution of about 1: 1.
0 μm.

[0003] Since infrared microscopes can be analyzed nondestructively at room temperature and normal pressure, the range of samples that can be measured is wide. It is used for analysis of fine particles, foreign substances and defects in materials, composition analysis of composite materials, research on biological tissues, research on material composition, structure, crystallinity, anisotropy of molecules and crystals, and the like. One example of the principle is that infrared light from an interferometer of a Fourier transform infrared spectrophotometer is guided to an infrared microscope through a reflecting mirror, and is focused on a sample by using a concave mirror to about 1 mm. The objective mirror is Cassegrain type and 1
It has a magnification of about 0 to 40 times. In order to detect only the light transmitted through the sample, a stop (variable aperture) is placed on the sample portion or the image forming portion, and the light passing through the stop (variable aperture) is condensed and a small area semiconductor detector (MCT)
And an infrared spectrum is obtained by Fourier transform.

FIG. 3 shows an example of an infrared microscope used in combination with a conventional Fourier transform infrared spectrophotometer 60. This apparatus can be used in either a transmission method or a reflection method. When using the transmission method, the focus adjustment dial 9 is provided on the side surface of the apparatus main body, and the sample stage 6 can be moved in the vertical direction by rotating the focus adjustment dial 9. The reflection observation illumination halogen lamp 12 is turned on, the sample 13 is placed on the sample stage 6, the observation is performed from the eyepiece lens 2, the focus adjustment dial 9 is rotated, and the surface of the sample 13 is reflected by the reflected light so that the focal plane of light ( (A position where the image can be observed sharply). Then, the halogen lamp 12 for reflection observation illumination is turned off. Next, infrared light from the Michelson interferometer of the Fourier transform infrared spectrophotometer 60 is reflected by the transmission / reflection switching mirror 10 and transmitted through the reflection mirror 31 via the reflection mirrors 37 and 36 shown in the lower part of the figure. Then, the light is reflected by the reflecting mirror 32 and enters the condensing mirror 7 (Casegrain mirror). The light is converged to a diameter of about 1 mm and applied to the sample 13 (sample) on the sample stage 6.

On the other hand, the light transmitted through the sample is condensed by a reflecting objective mirror 4a (Cassegrain mirror) having a magnification of about 15 and transmitted through a reflecting mirror 33, and the variable aperture 3, reflecting mirror 3
8 and the concave reflecting mirror 4 via the reflecting mirrors 39 and 40.
The light is condensed at 1 and enters the MCT detector 11 having a small area and is detected. The detected signal is Fourier transformed into an infrared spectrum.

FIG. 4 shows a case in which the reflection method is used. A focus adjustment dial 9 is provided on the side of the apparatus main body,
By rotating, the sample stage 6 can be moved in the vertical direction. The reflection observation illumination halogen lamp 12 is turned on, the sample 13 is placed on the sample stage 6, the observation is performed from the eyepiece lens 2, the focus adjustment dial 9 is rotated, and the surface of the sample 13 is reflected by the reflected light so that the focal plane of light ( (A position where the image can be observed sharply). Then, the reflection observation illumination halogen lamp 12 is turned off.

Next, infrared light from the Michelson interferometer of the Fourier transform infrared spectrophotometer 60 is reflected by the transmission / reflection switching mirror 10 and reflected by the reflection mirrors 34 and 35 above the figure. The light is reflected at 33, enters the reflection objective mirror 4a (Cassegrain mirror), is squeezed to a diameter of about 1 mm, and strikes the sample 13 (sample) on the sample stage 6. On the other hand, the light reflected from the sample is condensed by a reflecting objective mirror 4 (Cassegrain mirror) having a magnification of about 15 times, passes through the reflecting mirror 33, passes through the variable aperture 3, passes through the reflecting mirror 38, and passes through the reflecting mirror 3
The light is condensed by the concave reflecting mirror 41 through the mirrors 9 and 40 and enters the MCT detector 11 having a small area to be detected. The detected signal is Fourier transformed into an infrared spectrum.

Usually, since the size of the sample is smaller than the entire field of view, masking is performed by the variable aperture 3 in accordance with the sample. Further, transmission measurement and reflection measurement can be easily selected by switching the transmission / reflection switching mirror 10. In the case of the transmission method, it is necessary to collect a small sample and manufacture a thin section. In the reflection method, the amount of light is insufficient due to scattering, and the shape of the absorption band is distorted due to the effect of specular reflection.Therefore, this method is not used for general samples. In exceptional cases, there is an advantage that the optical path length is doubled by reflection, and measurement can be performed with the same spatial resolution as the transmission method.

Further, the sample stage 6 is scanned by a microcomputer to perform a three-dimensional mapping of the material surface. On the other hand, when observing the visible image of the sample with eyes, photographing, or observing with a TV monitor, when observing with transmitted light, use the halogen lamp 8 for transmission observation illumination.
Is applied to the sample 13 (sample) on the sample stage 6 by the condensing mirror 7 by the reflecting mirrors 31 and 32, and the transmitted light passes through the reflecting objective mirror 4 a and the reflecting mirror 33, and passes through the variable aperture 3. Pass through the reflecting mirror 38 and the prism 4
The sample image is reflected from the eyepiece 2 and observed from the eyepiece lens 2.
In addition, a photographing camera or a TV camera is attached to the photographing device mounting opening 1 to photograph or photograph. When observing with reflected light, light from the halogen lamp 12 for reflection observation illumination is reflected by the reflecting mirror 42, reflected by the reflecting mirror 38, passes through the variable aperture 3, passes through the reflecting mirror 33, and is reflected by the reflecting objective mirror. 4 and the sample 13 on the sample stage 6
(A sample), and the reflected light is condensed by a reflecting objective mirror 4a and transmitted through a reflecting mirror 33 to change the variable aperture 3
Are reflected by the reflecting mirror 38, reflected by the prism 43, and the sample image is observed from the eyepiece 2. In addition, a photographing camera or a TV camera is attached to the photographing device mounting opening 1 to photograph or photograph.

[0010]

The conventional infrared microscope is constructed as described above. The infrared measurement transmitted through the sample 13 (sample) is condensed and the MCT detector 11 extracts a signal to measure the transmission. The MCT detector 11 collects light reflected from the sample 13 (sample) by collecting light reflected from the sample 13 (sample). In order to realize such a structure, the infrared microscope is composed of two Cassegrain mirrors (condensing mirror 7,
It is necessary to provide a reflection objective 4a) and perform optical adjustment so that a sufficient amount of light can be obtained in both the transmission mode and the reflection mode.
It is difficult to adjust to meet these requirements.
In order to balance the two modes of reflection, it was inevitable to use the device in a state deviating from its optimal state.

If it is intended to realize both the transmission mode and the reflection mode with a single device, a complicated optical system having many optical elements is arranged, and the loss of the amount of infrared light is also increased. At the time of the adjustment, it is necessary to adjust the transmission and reflection so that a certain level of performance can be obtained. Therefore, there is a problem that it is necessary to use the transmission and reflection in a state deviating from the respective optimum values.

The present invention has been made in view of such circumstances, and provides an infrared microscope that can be used in an optimal state in both transmission and reflection modes with a simple optical system using a small number of optical elements. The purpose is to do.

[0013]

In order to achieve the above-mentioned object, an infrared microscope of the present invention is characterized in that, in an infrared wavelength region, light is condensed to a very small area by a concave mirror, and light transmitted or reflected on a minute sample is reduced. In an infrared microscope that can observe microscopic light and visible images by detecting with a semiconductor detector through a slit that limits the field of view of infrared measurement, a transmission mirror provided under the sample stage for transmission measurement Instead of a flat mirror, which allows transmission measurement of an infrared transmitting sample in the reflection measurement mode, adjusting means for moving and adjusting the vertical position of the flat mirror, and transmitting infrared light from the infrared spectrophotometer to the upper side of the sample. And an introduction means for introducing from the

The infrared microscope according to the present invention is configured as described above. By arranging a plane mirror in place of the condensing mirror (Cassegrain mirror) provided on the lower side used in the transmission mode, the infrared microscope is operated in the reflection mode. Then, the plane of the plane mirror is focused, a transmission sample (sample) is set on the plane mirror, and the sample for the transmission mode can be measured in the reflection mode. Since both reflection / transmission samples can be measured in the reflection mode, the optical system for transmission measurement can be eliminated, and the optical system can be simplified, thereby reducing optical loss. is there. Since the transmission mode substantially disappears even during the adjustment, the reflection mode can be optimized.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the infrared microscope according to the present invention will be described with reference to FIGS. FIG. 1 is a view showing a transmission measurement mode of the infrared microscope of the present invention, and FIG. 2 is a view showing a reflection measurement mode of the present invention. This infrared microscope includes a plane mirror 14 detachably mounted on the sample stage 6 instead of the condenser mirror 7 provided below the sample stage 6 of the conventional apparatus shown in FIG. A sample stage up / down adjustment dial 9a for moving the sample stage 6 up and down,
A fixed reflecting mirror 10a, a reflecting mirror 34 for introducing infrared light from the Fourier transform infrared spectrophotometer 60 into the apparatus,
35, 33, and the introduced infrared light is squeezed to a diameter of about 1 mm, applied to the plane mirror 14 or the sample 13 (sample) on the sample stage 6, and the reflected infrared light is taken out at a magnification of about 15 times. The upper Cassegrain 4, the variable aperture 3 for limiting the field of view of the output light from the upper Cassegrain 4, the reflecting mirrors 39, 40 and 41 for introducing the infrared light passing through the variable aperture 3 to the MCT detector 11, An MCT detector 11 for detection, an observation illumination halogen lamp 12a for illuminating the sample 13 (sample), and reflecting mirrors 42 and 38;
It is composed of a reflecting mirror 38, a prism 43, and an eyepiece 2 for observing a visible image of the sample 13 (sample) with eyes, and an imaging device mounting opening 1 for taking a photograph or observing with a TV monitor. ing.

In the fixed reflection mirror 10a, infrared light from the Michelson interferometer of the Fourier transform infrared spectrophotometer 60 is introduced into the microscope by the fixed reflection mirror 10a. In a conventional microscope, as shown in FIG. 3, the transmitted / reflective switching mirror 10 can be switched downward in the transmission measurement mode, and can be switched upward in the reflection measurement mode, as shown in FIG. Although the mirror switching drive unit 15 is provided in this embodiment, since the infrared light only needs to be introduced to the upper side in both the reflection measurement mode and the transmission measurement mode in this microscope, the fixed reflection mirror 10a is fixed and incorporated.

The sample stage vertical adjustment dial 9a is provided on a side surface of the apparatus main body, and can rotate the sample stage 6 in the vertical direction (Z) by rotating. Thereby, the reflection sample or the plane mirror 1 is placed on the sample stage 6.
The surface of the reflection sample or the surface of the plane mirror 14 can be positioned on the focal plane of light by mounting the device 4 and observing from the eyepiece 2. In addition, position adjustment knobs (not shown) for moving the sample stage 6 in the horizontal direction (X-Y) are provided on the side surfaces of the sample stage 6 in the X direction and the Y direction, respectively. The placed sample 13 or the plane mirror 14 can be moved to a position to be measured in the horizontal direction (X-Y).

The plane mirror 14 is detachably set on the sample stage 6 so as to be movable in the horizontal direction (XY) and the vertical direction (Z), and is used in the transmission measurement mode. The infrared light is squeezed by the Cassegrain 4 to about 1 mm in diameter, and adjusted by the sample stage up / down adjustment dial 9a so that the reflection surface (upper surface) of the plane mirror 14 comes to its focal plane. Next, sample 13
(Sample) is set thereon. Then, infrared light from above is reflected by the plane mirror 14, and the reflected infrared light passes through the sample 13 (sample) and enters the upper Cassegrain 4.

The upper Cassegrain 4 is a reflection objective mirror having an opening at the center of the concave mirror through which light can enter and exit, having a reflection mirror inside, and reflecting light from the opening with the internal reflection mirror. The light is reflected and focused to a diameter of about 1 mm. Further, light emitted from the focal position in the opposite direction can be extracted from the opening at a magnification of about 15 times. The sample stage 6 can move in the horizontal direction (XY) and the vertical direction (Z). In the reflection measurement mode, the sample 13 (sample) is directly set on the sample stage 6 without using the plane mirror 14, and is adjusted vertically (Z direction) by the sample stage up / down adjustment dial 9a. Then, infrared light from above is narrowed by the upper Cassegrain 4 to a diameter of about 1 mm, and the sample 13 is placed at the focal position.

The variable aperture 3 limits the field of view of the infrared image of the sample 13 to be measured.
3 selects that aperture. The MCT detector 11 is a quantum semiconductor detector having a composition of HgCdTe and is abbreviated as MCT (Mercury Cadmium T).
elluride) detector. Since the light receiving surface is very small, the light is condensed by the concave reflecting mirror 41 via the reflecting mirrors 39 and 40, and infrared light is detected on the light receiving surface having a small area. The MCT detector 11 is cooled to a low temperature by liquid nitrogen or the like to suppress generation of free carriers due to thermal excitation.
Then, the output signal of this detector is Fourier-transformed to obtain an infrared spectrum of the sample.

The observation illumination halogen lamp 12a is a lamp for irradiating the sample 13 with visible light in order to observe a visible image of the sample 13, and in the reflection measurement mode, the sample 13 on the sample stage 6 is used. Irradiation so that the surface of the can be observed. In the transmission measurement mode, the sample 13 set on the plane mirror 14 is irradiated, the light is reflected by the plane mirror 14, and the reflected light is reflected on the sample 13.
, The image of the sample 13 due to the transmitted light can be observed.

Next, the operation of the microscope will be described. In the case of the transmission measurement mode shown in FIG.
Is mounted with a plane mirror 14. Next, the power of the observation illumination halogen lamp 12a is turned on, and the surface on the plane mirror 14 is irradiated via the reflecting mirrors 42 and 38 and the upper Cassegrain 4.
The surface of the plane mirror 14 is observed by the eyepiece 2. At this time, the surface of the plane mirror 14 is set to a focal position (a position where a focused surface image is observed) by adjusting the sample stage vertical adjusting dial 9a. Next, the sample 13 is set on the plane mirror 14. Then, the position of the sample 13 to be measured by the eyepiece 2 is set by moving the sample stage 6 only in the XY directions. When the setting is completed, the power of the observation illumination halogen lamp 12a is turned off.

Next, infrared light from the Fourier transform infrared spectrophotometer 60 is transmitted to the fixed reflecting mirror 10a, the reflecting mirrors 34,
It is introduced into the upper Cassegrain 4 via 5 and 33, passes through the sample 13, and is focused on the surface of the plane mirror 14 to have a diameter of about 1 mm. The light reflected on the surface of the plane mirror 14 passes through the sample 13 and is collected by the upper Cassegrain 4 at a magnification of about 15 times. The collected transmitted infrared light passes through the reflecting mirror 33, passes through the variable aperture 3, passes through the reflecting mirror 38, is condensed by the concave reflecting mirror 41 via the reflecting mirrors 39 and 40, and has a small area. The light enters the light receiving surface of the MCT detector 11 and is detected. The detected signal is Fourier transformed into an infrared spectrum.

In the case of the reflection measurement mode shown in FIG. 2, the sample 13 is set on the sample stage 6. Then, the power of the observation illumination halogen lamp 12a is turned on, and the reflecting mirror 4 is turned on.
2, 38, the surface of the sample 13 on the sample stage 6 is irradiated via the upper Cassegrain 4. The position of the sample 13 to be measured by the eyepiece 2 is set by moving the sample stage 6. At this time, the surface of the sample 13 is set at the focal position by adjusting the sample stage vertical adjustment dial 9a. Then, the power of the observation illumination halogen lamp 12a is turned off.

Next, infrared light from the Fourier transform infrared spectrophotometer 60 is transmitted to the fixed reflecting mirror 10a, the reflecting mirrors 34 and 35,
33 to the upper Cassegrain 4 and the sample 13
The light is condensed on the surface of the substrate and becomes about 1 mm in diameter. The light reflected on the surface of the sample 13 is condensed by the upper Cassegrain 4 having a magnification of about 15 times, transmitted through the reflecting mirror 33, passed through the variable aperture 3, transmitted through the reflecting mirror 38, and transmitted through the reflecting mirrors 39 and 40. The light is condensed by the concave reflecting mirror 41 through the light receiving surface of the MCT detector 11 having a small area and is detected. The detected signal is Fourier transformed into an infrared spectrum.

This infrared microscope is an optical system for transmission measurement (condensing mirror 7, reflecting mirrors 32, 31, and 36) of a conventional infrared microscope.
37), in which the halogen lamp 8 for transmission observation illumination and the mirror switching drive unit 15 are not required, and the plane mirror 14 is installed instead of the condenser mirror 7 (cassegrain mirror for transmission).
After focusing on the surface 4, the sample 13 is set on the surface of the plane mirror 14 to perform transmission measurement. In this configuration, the transmission / reflection switching mirror 10 mounted on the conventional mirror switching drive unit 15 is replaced with a fixed reflection mirror 10a.
And the optical axis adjustment becomes easy. In addition, by reviewing the arrangement of the optical system, the fixed reflection mirror 10a
Can be eliminated. For example, it may be designed so that infrared light from the Fourier transform infrared spectrophotometer 60 can be directly input to the reflecting mirror 33. The loss of light can be reduced by eliminating the reflector in the middle. Since the optical adjustment only needs to be performed in the reflection measurement mode, there is no need to perform operations such as balancing the amounts of transmitted and reflected light.

In the above embodiment, the optical system before the MCT detector 11 is a combination of the plane mirror 40 and the elliptical concave mirror 41, but can be replaced by a lens and a plane mirror. The structure is further simplified by using a lens and a plane mirror. Further, the reflecting mirrors 34 and 35 and the reflecting mirrors 37 and 36 can be replaced with one parabolic mirror. A parabolic mirror also simplifies the structure. In the above embodiment, the plane mirror 14 is mounted on the sample stage 6, but
A plane mirror stage on which a plane mirror 14 different from the sample stage 6 is mounted may be provided. In this case, in the reflection measurement mode, the sample 13 may be set on the sample stage 6, and in the transmission measurement mode, the sample 13 may be set on the plane mirror 14 of the plane mirror stage.

[0028]

The infrared microscope of the present invention is constructed as described above. A flat mirror is installed instead of the lower Cassegrain mirror of the conventional infrared microscope, and a transmission sample (sample) is set on the flat mirror. Since the sample for the transmission mode can be measured in the reflection mode, the optical system for the transmission measurement can be eliminated to simplify the optical system. Therefore, the number of optical elements is reduced, the number of parts is reduced, and the number of man-hours for assembling and adjusting are reduced, so that the cost can be reduced. Further, by reducing the number of optical elements, the amount of light loss can be reduced, the adjustment can be optimally performed only in the reflection mode, and the performance can be improved as compared with the related art.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of a transmission mode of an infrared microscope of the present invention.

FIG. 2 is a diagram showing one embodiment of a reflection mode of the infrared microscope of the present invention.

FIG. 3 is a diagram showing a transmission mode of a conventional infrared microscope.

FIG. 4 is a diagram showing a reflection mode of a conventional infrared microscope.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Image pick-up device mounting opening 2 ... Eyepiece 3 ... Variable aperture 4 ... Upper Cassegrain 4a ... Reflective objective lens 5 ... Visible objective lens 6 ... Sample stage 7 ... Condenser mirror 8 ... Halogen lamp for transmission observation illumination 9 ... Focus adjustment dial 9a: Sample stage up / down adjustment dial 10: Transmission / reflection switching mirror 10a: Fixed reflection mirror 11: MCT
Detector 12 ... Halogen lamp for reflection observation illumination 12a ... Halogen lamp for observation illumination 13 ... Sample 14 ... Plane mirror 15 ... Mirror switching drive unit 31 ... Reflection mirror 32 ... Reflection mirror 33 ... Reflection mirror 34 ... Reflection mirror 35 ... Reflection mirror 36 ... Reflecting mirror 37 ... Reflecting mirror 38 ... Reflecting mirror 39 ... Reflecting mirror 40 ... Reflecting mirror 41 ... Reflecting mirror 42 ... Reflecting mirror 43 ... Prism 60 ... Fourier transform infrared spectrophotometer

Continued on the front page F-term (reference) 2G059 AA05 BB08 DD13 EE01 EE02 EE12 FF03 GG10 HH01 JJ11 JJ12 JJ13 JJ14 KK01 PP04 2H052 AB06 AC04 AC05 AC13 AC14 AC27 AC30 AD08 AD20 AD33 AF07 AF14

Claims (1)

[Claims] In the infrared wavelength region, light is transmitted to or reflected from a small sample by squeezing light to a very small area with a concave mirror using a concave mirror and detecting light with a semiconductor detector through a slit that limits the field of view of infrared measurement. Infrared microscope that can perform visible light image observation and perform transmission measurement of infrared transmission sample in reflection measurement mode instead of the transmission measurement focusing mirror provided under the sample stage. An infrared microscope comprising: a flat mirror that has been adjusted; an adjusting unit that can move and adjust the vertical position of the flat mirror; and an introducing unit that introduces infrared light from an infrared spectrophotometer from above the sample.