JPH05340870A - Total-reflection absorption spectrum measuring instrument - Google Patents

Abstract

PURPOSE:To expand the applicable scope of the total-reflection absorption spectrum measuring method (ATR) by making incident light to incident to an ellipsoidal mirror through one focal point of the mirror and positioning the surface of a sample to the other focal point or the image point of a plane mirror at the same focal point. CONSTITUTION:Projected infrared rays must be condensed to one focal point F' side of an ellipsoidal mirror 1 after the rays are reflected by a notched mirror 2 and the mirror 1. When an object point 0 is positioned on the extension line of the center axis M of the mirror 1 on the focal point F' side and a plane mirror 3 which is the auxiliary mirror of a Newtonian reflecting microscope is positioned so that the points 0 and F' can become symmetrical with respect to the mirror 3, the infrared rays can be condensed to the point 0. In addition, after the title semispherical total-reflection absorption spectrum measuring instrument having its center at the point 0, namely, an ATR prism 4 is positioned, a sample is positioned below the prism 4. Therefore, the rays condensed to the point 0 are reflected by the mirror 1 as if they are emitted from the focal point F' and condensed to the other focal point F of the mirror after they are reflected by the sample and mirror 3. The rays condensed to the point F are photometrically measured with a measuring instrument provided on the outside of the figure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a total reflection absorption spectrum measuring apparatus using a reflection microscope system.

[0002]

2. Description of the Related Art Total reflection absorption spectrum measurement method (ATR)
Contact the sample surface with a transparent material with a lower refractive index than the sample, and from this low refractive index transparent material side, enter the measurement light at an incident angle where total reflection occurs at the interface with the sample, and A method of measuring the absorption characteristics of a sample by detecting the absorption and extinction of the sample. Conventionally, in the case of measuring infrared light, an infrared microspectroscopic device constituted by a reflection optical system is used. An apparatus as shown in is used.

FIG. 8 shows a part of an objective mirror of a Cassegrain infrared microspectrophotometer. The objective is a primary mirror with a hole in the center 1
0 and a secondary mirror 11 coaxial with the main mirror 10, and monochromatic light emitted from a spectroscope (not shown) is located in the right half of the optical axis downward in the figure and is parallel to the optical axis. Light is reflected by the primary mirror 10 and the secondary mirror 11, and is condensed at the focal point 0 of the objective mirror optical system. The sample S is brought into contact with the lower surface of the hemispherical ATR prism 4 centered on the surface 0 point. In this case, the light focused on the 0 point is not refracted by the ATR prism, is focused on the 0 point as it is, is totally reflected by the sample surface, and goes up the left half of the optical axis of the objective optical system for detection. To be done.

In such a Cassegrain type reflection microscope, since the structure is such that light is condensed below the secondary mirror 11 facing upward, the light is reflected from the portion of the primary mirror 10 above the secondary mirror 11. Since the light is focused at the 0 point, the incident angle of the sample irradiation light on the sample surface cannot be set sufficiently large, and total reflection is caused at the contact surface between the ATR prism and the sample. It is necessary to make the refractive index of the ATR prism sufficiently smaller than that of the sample, and there is a problem that depending on the sample, there is no suitable substance for the ATR prism and the ATR measurement method cannot be performed.

[0005]

SUMMARY OF THE INVENTION According to the present invention, the ATR measurement using a reflection microscope increases the incident angle of the sample irradiation light on the sample surface so that the measurement can be performed even if the incident angle of the incident light is wide. However, the purpose is to expand the applicable range of ATR.

[0006]

In a microscopic total reflection absorption spectrum measuring apparatus, an ellipsoidal mirror is used as a reflecting objective as shown in FIG. 1, and incident light to the apparatus is focused on one side of the ellipsoidal mirror. A reflecting surface is directed to the same ellipsoidal mirror between the light projecting means for making the light incident on the same ellipsoidal mirror through F and the other focus F ′ of the ellipsoidal mirror and the apex on the side of this focus F ′ of the same ellipsoidal mirror. And the plane mirror 3 of the secondary mirror inserted perpendicularly to the central axis M of the ellipsoidal mirror that connects both focal points of the same ellipsoidal mirror, and this plane mirror 3
Regarding the above, a hemispherical ATR prism 4 centered on a point 0 symmetrical to the other focus F ′ is provided. Alternatively, FIG. 4 and FIG.
As shown in, the focal point of the sample surface was directly positioned at one focal point of the ellipsoidal mirror.

[0007]

According to the present invention, the plane mirror of the secondary mirror is inserted between the focal point and the apex of the ellipsoidal mirror so that the image of the focal point on the sample becomes the focal point. And the focal point of the ellipsoidal mirror can be made arbitrarily small, and by making this space small, the incident angle and the reflection angle at the condensing point of the sample surface can be made arbitrarily close to 90 °. Becomes Alternatively, by placing the sample surface directly on the focal point of the ellipsoidal mirror, the incident angle on the sample can be further increased.

[0008]

FIG. 1 shows an embodiment of the present invention. In the figure, 1 is an ellipsoidal mirror whose focal points are F and F '. Reference numeral 2 denotes a notched mirror as shown in FIG. 2, in which the notched edge 2A is in contact with the central axis M connecting the two focal points F and F ′, and the mirror portion 2B is arranged so as to be located on the left side of the central axis in the figure. The point P is a point symmetrical to the focal point F with respect to the mirror surface of the cutout mirror 2,
When the infrared light is projected from the infrared light source (not shown) by the light projecting means (not shown) onto the cutout mirror 2, the projected infrared light is reflected by the cutout mirror 2. It should be reflected by the ellipsoidal mirror 1 and condensed at the other focal point F ′, but the object point (focus point) on the extension line on the other focal point F ′ side on the central axis M. By arranging 0 and arranging the plane mirror 3 so that 0 and F ′ are symmetric with respect to the plane mirror 3 of the secondary mirror of the Newton-type reflection microscope, the infrared light which should be focused on F ′ is at the object point 0. Is focused on. At the object point 0, a hemispherical ATR prism 4 centered at 0 is arranged on the incident side of infrared light (upper side in the figure), and a sample S is arranged below. Reference numeral 5 is an aperture arranged between the cutout mirror 2 and the ellipsoidal mirror 1, and has two semicircular slits 5A and 5B as shown in FIG. 3, and the slit 5A is an entrance slit, and the cutout mirror 2 The infrared light emitted from the ellipsoidal mirror 1 is shielded from light other than the required angle, and the slit 5B is reflected from the sample at the 0 point by the exit slit, and further the light reflected from the ellipsoidal mirror 1 is reflected. Pass through. The light focused on the object point 0 is reflected by the sample S and is reflected by the plane mirror 3, so that it is reflected by the ellipsoidal mirror 1 and is focused on the focus F as if it were the light emitted from the focus F ′. To be done. The light condensed at the focal point F is measured by a measuring device (not shown). FIG. 4 shows a second embodiment of the present invention in which a secondary mirror is not used. The focal point 0 on the sample surface is directly placed on one focus F ′ of the ellipsoidal mirror 1. The parts corresponding to those of the structure of FIG. 1 are denoted by the same reference numerals as those in the figure, and the description thereof will be redundant and will not be repeated. FIG. 5 shows a third embodiment of the present invention, which is a modification of the embodiment of FIG. 4 and is suitable for a case where a particularly large incident angle is required. FIG. 6 shows a fourth embodiment of the present invention, which is a modification of FIG. 1, in which incident light and reflected light are located at a position corresponding to the focal point F of the ellipsoidal mirror 1 formed by the cutout mirror 2 as shown in FIG. With the aperture 6 of 2, the light flux is further narrowed, and it is possible to perform measurement in a finer range.

[0009]

According to the present invention, by using a Newton-type reflective objective mirror using an ellipsoidal mirror as a concave mirror, it becomes possible to perform ATR measurement at a large incident angle (> 60 degrees), and The degree of freedom for the material of the ATR prism is increased, and the measurable substance range is widened.

[Brief description of drawings]

FIG. 1 is a side configuration diagram of an embodiment of the present invention.

FIG. 2 is a detailed view of the cutout mirror in the above embodiment.

FIG. 3 is a detailed view of the aperture in the above embodiment.

FIG. 4 is a side view of the second embodiment of the present invention.

FIG. 5 is a side view of the third embodiment of the present invention.

FIG. 6 is a side view of the fourth embodiment of the present invention.

FIG. 7 is a detailed view of the aperture in the above embodiment.

FIG. 8 is a side view of a conventional example.

[Explanation of symbols]

 1 Ellipsoidal mirror 2 Notched mirror 3 Plane mirror 4 ATR prism 5 Aperture

Claims (1)

[Claims] 1. A total reflection absorption spectrum measuring apparatus using a reflection microscope, wherein an ellipsoidal mirror is used as a reflection objective mirror,
Total reflection absorption spectrum characterized in that incident light is made incident on the same ellipsoidal mirror through one focal point of the ellipsoidal mirror and the sample surface is positioned at the image point of the other focal point or the plane mirror of the same focal point. measuring device.