JPH1151858A - Microscopic fourier transform infrared spectrophotometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a microscopic Fourier transform spectrophotometer having a small and compact overall structure in which compact optical arrangement can be realized. SOLUTION: The spectrophotometer comprises an infrared light source 2 for irradiating a sample S with an infrared light IR through an interferometer 3 and analyzes the infrared light IR transmitted through the sample S or the infrared light IR transmitted through the sample S and reflected on a member 8 for holding the sample S. A concave mirror 5 is disposed on the post-stage of the interferometer 3 and a convex mirror 19 sharing the geometric focal point with the concave mirror 5 is located in the reflection light path retractively therefrom.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a microscopic Fourier transform infrared spectrophotometer (hereinafter, referred to as microscopic FTIR).

[0002]

2. Description of the Related Art Microscopic FTIR is useful for measuring a minute sample by attaching an infrared microscope to a Fourier transform infrared spectrophotometer (FTIR), and there are a transmission method and a reflection method as microspectroscopic measurement methods. .

That is, in the transmission method, infrared light that has exited the interferometer is focused on a sample surface via a focusing mirror located below the sample. The infrared light transmitted through the sample forms an enlarged image with an objective mirror, and only the infrared light passing through a mask placed on the image forming surface is guided to the detector. On the other hand, in the reflection method, infrared light that has exited the interferometer is guided to the upper part of the microscope, reflected only half by a half mirror or an edge mirror, and condensed on a sample surface via an objective mirror. The infrared light transmitted through the sample and reflected by the reflector holding the sample is transmitted again through the sample, forms an enlarged image with the objective mirror, and only the infrared light that has passed through the mask placed on this image plane Is guided to the photodetector.

FIG. 2 schematically shows a conventional micro FTIR optical system capable of measuring microspectroscopy by both the transmission method and the reflection method. In this figure, reference numeral 1 denotes an appropriate material. The housing is configured to hermetically shut off the inside and the outside, and the following devices are provided inside the housing. That is,
2 is an infrared light source, 3 is an interferometer, 4 is a plane mirror that bends the parallel infrared light IR from the interferometer 3 by 90 ° and reflects it downward, and 5 is a parallel infrared light IR from the plane mirror 4 that is 90 °. It is a parabolic mirror (a kind of concave mirror) that bends and reflects in the horizontal direction.

[0005] Reference numeral 6 denotes a parabolic mirror which is provided farther than a focal position 7 with respect to the parabolic mirror 5, and which transmits infrared light IR from the parabolic mirror 5 to 90.
An ellipsoidal mirror (a type of condensing mirror) that bends and reflects upward and condenses it on the sample S held by the sample holding member 8, 9 is a Cassegrain objective mirror, and 10 is an image thereof formed on the Cassegrain objective mirror 9. A half mirror provided closer to the position, 11 is an aperture as a mask provided at an image forming position of the Cassegrain objective mirror 9, and 12 is an infrared light IR passing through the aperture 11.
Is a plane mirror for appropriately reflecting infrared light IR from the plane mirror 12 to the photodetector 14.

Reference numeral 15 denotes a parabolic mirror provided so as to be able to enter and exit the reflected light path 16 of the parabolic mirror 5 with respect to the ellipsoidal mirror 6, and the focal point is shared with the parabolic mirror 5. From the reflected light path 16 (indicated by a phantom line), moving in the direction of arrow A or B in FIG. And a state (shown by a solid line) located in the reflection optical path 16. Reference numeral 17 denotes a concave mirror that forms a reflection measurement optical path 18 together with the parabolic mirror 15. The concave mirror 17 is a concave mirror that bends the parallel infrared light IR from the parabolic mirror 15 by 90 ° and reflects it in the direction of the half mirror 10. . Note that an edge mirror may be used instead of the half mirror 10.

In the optical system having the above-described configuration, when microspectroscopic measurement is performed by the transmission method, a sample holding member 8 made of an infrared light transmitting material is used, and the sample S is held on the material. Then, the parabolic mirror 15 is moved in the direction of arrow A, and the reflected light path 1
6. In this state, the infrared light IR that has exited the interferometer 3 passes through the plane mirror 4 and the parabolic mirror 5, and then enters the elliptical mirror 6. Then, the infrared light IR reflected by the ellipsoidal mirror 6 passes through the sample holding member 8, and then the sample S
The infrared light IR condensed on the surface and transmitted through the sample S forms an image at the aperture 11 by the Cassegrain objective mirror 9,
Further, the photodetector 1 passes through a plane mirror 12 and a concave mirror 13.
4 is incident.

When microspectroscopic measurement is performed by the reflection method, a sample holding member 8 is used, for example, a polished metal plate that reflects infrared light, and the sample S is held on the metal plate.
Then, the parabolic mirror 15 is moved in the direction of arrow B so as to be positioned in the reflection optical path 16 of the parabolic mirror 5 as shown by the solid line. In this state, the infrared light I
R passes through a plane mirror 4 and a parabolic mirror 5 and then a parabolic mirror 15
Incident on. Then, the infrared light IR reflected by the parabolic mirror 15 becomes parallel light and enters the concave mirror 17 from below,
The light is bent by 90 ° by the concave mirror 17, guided to the half mirror 10 located above the Cassegrain objective mirror 9, reflected by the half mirror 10, and condensed on the sample S surface via the Cassegrain objective mirror 9. The condensed light passes through the sample S and is reflected by the sample holding member 8, passes through the sample S again, forms an image at the aperture 11 by the Cassegrain objective mirror 9, and further passes through the plane mirror 12 and the concave mirror 13. The light enters the detector 14.

As described above, in the above-mentioned conventional microscopic FTIR, the position of the parabolic mirror 15 which is provided so as to be freely movable in and out of the optical path 16 between the parabolic mirror 5 and the ellipsoidal mirror 6 is in an outgoing state. Alternatively, by switching to the ON state, both the microspectroscopic measurement by the transmission method and the microspectroscopic measurement by the reflection method can be performed alternatively.

[0010]

However, in the conventional microscopic FTIR, the parabolic mirror 5 and the parabolic mirror 1 are not provided.
5, the parabolic mirror 15 needs to be arranged so that its focal point overlaps with the focal point of the elliptical mirror 6. Since the distance from the parabolic mirror 15 is the sum of the focal lengths of the both 5 and 15, it must be large, and the optical system of the microscopic FTIR cannot be made small and compact. The housing 1 is also large, and there is an inconvenience that the space for installation is required accordingly.

Further, in the micro FTIR, the longer the measured optical path length, the more susceptible to moisture and carbon dioxide in the air. As a method corresponding to this, it is conceivable to replace the inside of the housing 1 with an inert gas. However, since the housing 1 itself is large, there is a disadvantage that a large amount of the inert gas is required. There was also room for improvement.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-mentioned matters, and an object of the present invention is to provide a microscopic FTIR having a compact and compact structure which can be compactly arranged.

[0013]

In order to achieve the above object, according to the present invention, a sample is irradiated with infrared light from an infrared light source via an interferometer, and the infrared light or the sample transmitted through the sample is then irradiated. In a microscopic FTIR configured to analyze infrared light transmitted and reflected by a member holding a sample, a convex mirror sharing a geometrical focus with the concave mirror is provided in a reflection optical path of a concave mirror provided at a subsequent stage of the interferometer. , Are provided so as to be able to enter and exit the optical path.

In the micro FTIR having the above configuration, the distance between the concave mirror and the convex mirror is not the sum of the focal lengths of the concave mirror and the convex mirror, but can be smaller than the focal length of the concave mirror. Compared to this, the configuration can be made significantly smaller and more compact.

[0015]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows one embodiment of the present invention. The microscopic FTIR in this embodiment is shown in FIG.
The difference from the conventional microscopic FTIR shown in Fig. 1 is that a convex mirror sharing a geometrical focus with the concave mirror is provided in the reflected optical path of the concave mirror provided at the subsequent stage of the interferometer so as to be able to freely enter and exit the optical path. It is. In FIG. 1, FIG.
The same reference numerals as those in indicate the same items.

That is, in FIG. 1, reference numeral 19 denotes the interferometer 3
2 is a reverse parabolic mirror (a type of convex mirror) provided to be able to enter and exit the reflected light path 20 of the parabolic mirror 5 as a concave mirror provided at the subsequent stage, similar to the elliptical mirror 15 shown in FIG.
It moves in the directions of arrows A and B in the figure, and becomes a state deviating from the reflected light path 20 of the parabolic mirror 5 (a state shown by a virtual line) and a state located in the reflected light path (a state shown by a solid line). And shares a geometrical focus with the parabolic mirror 5. Therefore, when the inverted parabolic mirror 19 is at the position indicated by the solid line, the infrared light IR incident from the direction of the parabolic mirror 5 is bent upward by 90 ° to become parallel infrared light IR, and the parallel infrared light IR is transmitted to the concave mirror 17. Reflected toward.

Reference numeral 21 denotes a parabolic mirror 5 when the inverted parabolic mirror 19 is located at a position deviated from the reflected light path 20 as shown by a virtual line.
Is a plane mirror that bends the infrared light IR from the object by 90 ° and reflects it in the sample S direction. In this embodiment, the parabolic mirror 5
Is reflected by the plane mirror 21 and collected by the sample S.

In the microscopic FTIR having the above configuration, when microspectroscopic measurement is performed by the transmission method, the sample holding member 8 is required.
A sample made of an infrared light-transmitting material is used as the sample S. Then, the inverted parabolic mirror 19 is moved in the direction of arrow A so as to be out of the reflection optical path 20 of the parabolic mirror 5 as shown by a virtual line. In this state, the infrared light IR that has exited the interferometer 3 passes through the plane mirror 4 and the parabolic mirror 5, and then enters the plane mirror 21. And this plane mirror 21
The infrared light IR reflected by the sample is condensed on the surface of the sample S, and this sample S
The infrared light IR transmitted through is focused on the aperture 11 by the Cassegrain objective mirror 9, and further enters the photodetector 14 via the plane mirror 12 and the concave mirror 13.

When performing microspectroscopy measurement by the reflection method, a sample holding member 8 is used, for example, a polished metal plate that reflects infrared light, and the sample S is held on the plate.
Then, the inverted parabolic mirror 19 is moved in the direction of arrow B,
As shown by the solid line, it is assumed that it is located in the reflection optical path 20 of the parabolic mirror 5. In this state, the infrared light IR that has exited the interferometer 3 passes through the plane mirror 4 and the parabolic mirror 5 and then enters the inverted parabolic mirror 19. The infrared light IR reflected by the inverted parabolic mirror 19 becomes parallel light and enters the concave mirror 17 from below, is bent by 90 ° by the concave mirror 17, and is a half mirror positioned above the Cassegrain objective mirror 9. The light is guided to the half mirror 10, reflected by the half mirror 10, and condensed on the surface of the sample S via the Cassegrain objective mirror 9. The condensed light passes through the sample S and is reflected by the sample holding member 8, passes through the sample S again, forms an image at the aperture 11 by the Cassegrain objective mirror 9, and further passes through the plane mirror 12 and the concave mirror 13. The light enters the detector 14.

As described above, in the microscopic FTIR having the above-described configuration, the position of the inverted parabolic mirror 19 provided to be able to enter and exit the optical path 20 between the parabolic mirror 5 and the plane mirror 21 is set to the outgoing state or the incoming state. By switching to the state, it is possible to selectively perform both the microscopic light measurement by the transmission method and the microscopic light measurement by the reflection method.

In the microscopic FTIR, the distance between the parabolic mirror 5 and the inverted parabolic mirror 19 is 5, 1
9 is smaller than the focal length of the parabolic mirror 5 instead of the sum of the focal lengths of the focal lengths, so that the configuration can be made significantly smaller and more compact than the conventional microscopic FTIR. In particular, since the focal point of the parabolic mirror 5 is set to the set position of the sample S, the microspectroscopy measurement by the transmission method and the reflection method can be alternatively performed as in the conventional micro FTIR.

The present invention is not limited to the above-described embodiment. For example, another concave mirror may be used instead of the parabolic mirror 5, and instead of the inverted parabolic mirror 19, Other convex mirrors may be used.

[0023]

In the microscopic FTIR of the present invention, the distance between the concave mirror and the convex mirror is not the sum of the focal lengths of the concave mirror and the convex mirror, but can be smaller than the focal length of the concave mirror. An optical arrangement that is significantly smaller and more compact than FTIR is possible. Therefore, according to the present invention, a small and compact microscopic FTIR having a short measurement optical path length can be configured, and is less affected by moisture or carbon dioxide in the air, and highly accurate measurement can be performed. At the same time, it is possible to obtain a micro FTIR having excellent features such as a small installation space.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing an example of an optical configuration of a microscopic FTIR of the present invention.

FIG. 2 is a diagram schematically showing an optical configuration of a conventional microscopic FTIR.

[Explanation of symbols]

2 infrared light source 3 interferometer 5 concave mirror 8 sample holding member 19 convex mirror 20 reflected light path S sample and IR
... infrared light.

Claims (1)

[Claims] 1. A sample is irradiated with infrared light from an infrared light source via an interferometer, and the infrared light transmitted through the sample or the infrared light transmitted through the sample and reflected by a member holding the sample is analyzed. In the microscopic Fourier transform infrared spectrophotometer, a convex mirror sharing a geometrical focus with the concave mirror is freely inserted into and out of the optical path in the reflection optical path of the concave mirror provided at the subsequent stage of the interferometer. A microscopic Fourier transform infrared spectrophotometer, which is provided.