Cassegrain reflector for microscope, and microscope

Abstract

A Cassegrain reflector 100 for a detector comprises: a primary mirror 20 fixed to a housing 10 and having a through-hole 22 in a center part thereof; a slider 30 movably held by the housing 10, the moving direction being orthogonal to the central axis of the through-hole 22; and a secondary mirror 40 and a concave elliptical mirror 50 attached to the slider 30 and arranged in the moving direction thereof. The slider 30 can move to a first position such that the secondary reflector 40 is located on the central axis of the through-hole 22 and to a second position such that the concave elliptical mirror 50 is located on the central axis. At the first position, light is reflected, in order, by the secondary mirror 40 and the primary mirror 20 to form an image at a first point (an array detector) on the central axis of the through-hole 22. At the second position, light forms an image, by means of the elliptical concave mirror 50, at a second point (a single element detector) located in a direction different from the central axis.

Description

Cassegrain mirror for microscope and microscope

[0001] The present invention relates to a Cassegrain mirror for a microscope. In particular, it is configured to be able to select a condenser optical system suitable for measurement conditions. For example, a Cassegrain mirror can be selected for measurement conditions such as the device configuration, etc., and a condenser optical system other than the Cassegrain mirror can be selected for other measurement conditions. The present invention relates to a Cassegrain mirror for a microscope provided with a switching mechanism for a condenser optical system.

[0002] Microscopes for obtaining spectral information of minute sites on a sample are used in a very wide range, not only in academic and research fields dealing with minerals and living organisms, but also in industrial fields such as polymer materials, inorganic materials, electrical and electronic materials.

[0003] Usually, such a microscope has a sample placed on a stage, and the observed image of the sample is captured by a camera or the like and displayed as an X-Y coordinate system image on a display. The observer determines the site for which spectral information is to be obtained while looking at the displayed observed image. For example, a mark is placed at the position on the observed image. Also, an aperture is set for the determined site. In the acquisition of spectral information, transmitted light, reflected light or total reflected light from a minute site on the sample is condensed by a Cassegrain mirror, and by providing an aperture at the imaging position, the condensed region on the sample can be restricted. The light passing through the aperture of the aperture is condensed by the condenser optical system in front of the detector and forms an image on the element of the detector. By processing the signal thus detected with a computer or the like, the spectral information of the minute site is obtained.

[0004] In setting the aperture, the aperture to be selected may change depending on the nature of the method for obtaining spectral information. Here, taking the minute sites surrounded by the curves shown in FIGS. 12(A) to (C) as an example, the differences in the methods for obtaining each spectral information will be briefly described.

[0005] In the single-point measurement shown in Figure 12(A) and the multi-point measurement shown in Figure 12(B) (a type of mapping measurement), one or more focusing regions (in this case, rectangular regions) from which spectral information is desired are specified within the area of ​​a minute region. The shape, size, and angle of the aperture are set to match each focusing region, and spectral information of the focusing region is acquired.

[0006] On the other hand, in the imaging measurement shown in Figure 12(C) (a type of mapping measurement), an imaging measurement area including a minute area and its surroundings is specified, and the imaging measurement area is divided into numerous sections arranged vertically and horizontally (each section is hatched with diagonal lines), and one row of these sections (the area enclosed by a thick line) is designated as the focusing area. The shape, size, and angle of the aperture are set to match this linear focusing area, and spectral information of the numerous sections included in the focusing area is acquired together. Once spectral information for one row of sections is obtained, the aperture is aligned with the next row of sections, and spectral information is acquired together in the same way. By repeating this process, spectral information for all sections within the imaging measurement area is obtained.

[0007] Figure 13(A) shows a simplified example of a focusing optical system for single-point measurement described in Patent Document 1. Light passing through the aperture is focused by an elliptical concave mirror in front of the detector and imaged on the element of a single-element detector (single-element MCT detector) with a minute area. In single-point measurement, focusing efficiency is important in order to measure weak light contained in light from a wide area with high precision. For this reason, an elliptical concave mirror is preferred, which is inferior to a Cassegrain mirror in terms of chromatic aberration over a wide wavelength range, but is superior in terms of focusing efficiency.

[0008] Figure 13(B) shows an example of a focusing optical system for imaging measurement described in Patent Document 2. Light passing through the aperture is reflected by a plane mirror, then focused by a Cassegrain mirror in front of the detector, and imaged on an array of elements in a linear array MCT detector, where elements of a small area are arranged in a single row. In imaging measurements, the ability to accurately image the light passing through the aperture aperture onto the light-receiving surface of the array detector is important in order to acquire spectral information from multiple points at once. Therefore, although it is inferior to an elliptical concave mirror in terms of focusing efficiency, a Cassegrain mirror is preferred because it has excellent imaging performance due to its low chromatic aberration over a wide wavelength range and less image distortion.

[0009] Japanese Patent Publication No. 2001-174708 Japanese Patent Publication No. 2013-117549

[0010] As the above-mentioned literature shows, for example, when the detector configuration is changed, it is important to switch the configuration of the focusing optical system in front of the detector from a Cassegrain mirror to another focusing optical system configuration accordingly. There was a need to switch the focusing optical system used to different types depending on the differences in measurement conditions such as the instrument configuration. However, in order to switch between different focusing methods with a single microscope, for example, with the above-mentioned detector configuration, it would be necessary not only to have both a single-element detector and an array detector, but also to separately provide focusing optical systems (elliptic concave mirror and Cassegrain mirror) suitable for each detector, and to switch the optical path toward either focusing optical system. This would require a large amount of space, creating space constraints and making it impractical.

[0011] In an example of a different detector, Figure 13(C) shows a design in which a Cassegrain mirror is used in the focusing optical system in front of the detector to save space, and a switching mirror after the Cassegrain mirror switches the optical path to two types of detectors. As mentioned above, this is suitable for imaging measurements, but for single-point measurements where focusing efficiency is important, the light loss in the Cassegrain mirror has a significant impact, making it difficult to measure weak light contained in light from a wide area with high precision, and thus it cannot be said to be the optimal focusing optical system. Here, light loss in the Cassegrain mirror means that light from the aperture passes through the through hole in the center of the primary mirror (concave mirror) of the Cassegrain mirror to the secondary mirror (convex mirror), and a portion of it undergoes specular reflection in the center of the secondary mirror, and the light specularly reflected by the secondary mirror cannot reach the detector.

[0012] The present invention aims to provide a Cassegrain mirror for microscopes that allows switching between light-gathering optical systems (Cassegrain mirrors and other light-gathering optical systems) suitable for each measurement condition of the microscope, and that enables space saving, as well as a microscope equipped therewith.

[0013] In other words, the present invention relates to a Cassegrain mirror for a microscope, comprising: a housing; a primary mirror fixed to the housing and having a concave reflective surface and a through hole provided in the center of the concave reflective surface; a secondary mirror positioned on the central axis of the through hole and having a convex reflective surface opposite to the concave reflective surface; a secondary mirror moving member for moving the secondary mirror between a position on the central axis and a position off the central axis; at least one light-gathering optical element attached to the secondary mirror moving member together with the secondary mirror; and a drive unit for driving the secondary mirror moving member, wherein the at least one light-gathering optical element is positioned on the central axis when the secondary mirror is off the central axis, and when the secondary mirror is on the central axis by the secondary mirror moving member, the Cassegrain mirror consisting of the primary mirror and the secondary mirror gathers light incident on the through hole. The invention is characterized in that, when the sub-mirror moving member positions any of the at least one of the condensing optical elements on the central axis, the light incident on the through-hole is focused by the one condensing optical element without passing through the primary mirror.

[0014] Here, it is preferable that the at least one light-gathering optical element includes an off-axis reflecting condenser, and when the secondary mirror is on the central axis by the secondary mirror moving member, the light incident on the through hole is reflected by the secondary mirror and the primary mirror in that order to form an image at a first point on the extension of the central axis, and when the off-axis reflecting condenser is on the central axis by the secondary mirror moving member, the light incident on the through hole is reflected by the off-axis reflecting condenser in a reflection direction different from the central axis to form an image at a second point in that reflection direction.

[0015] Furthermore, it is preferable that the off-axis reflecting condenser is attached to the sub-mirror moving member via a posture changing means that changes the orientation of the reflective surface of the off-axis reflecting condenser, and that when the off-axis reflecting condenser is on the central axis, the posture changing means is configured to image the reflected light from the off-axis reflecting condenser at a third point on a reflection direction different from both the central axis and the reflection direction.

[0016] Furthermore, it is preferable that the at least one light-gathering optical element includes a condensing lens, and when the secondary mirror is on the central axis by the secondary mirror moving member, the light incident on the through hole is reflected by the secondary mirror and the primary mirror in that order to form an image at a first point on the extension of the central axis, and when the condensing lens is on the central axis by the secondary mirror moving member, the light incident on the through hole is formed by the condensing lens at any point on the extension of the central axis.

[0017] Furthermore, it is preferable that the secondary mirror moving member is a slider held in the housing so as to be movable in one direction, and that the direction of movement is perpendicular to the central axis of the through hole.

[0018] Alternatively, it is preferable that the secondary mirror moving member is a rotating member held in the housing, and the axis of rotation of the rotating member is parallel to the central axis of the through hole.

[0019] The present invention relates to a microscope for measuring the spectrum of a minute portion of a sample placed on a sample stage, comprising: a light irradiation means for irradiating the sample with light; and a light detection means for detecting transmitted light, reflected light, or total reflected light from the sample via an aperture, wherein the light detected by the light detection means is limited to light from a predetermined light-gathering area of ​​the sample by passing the transmitted light, reflected light, or total reflected light from the sample through the aperture, thereby enabling measurement, and wherein one of the above-described Cassegrain mirrors for microscopes is provided in the optical path from the light irradiation means to the light detection means.

[0020] Alternatively, the present invention relates to a microscope for measuring the spectrum of a minute portion of a sample placed on a sample stage, comprising: a light irradiation means for irradiating the sample with light; and a light detection means for detecting transmitted light, reflected light, or total reflected light from the sample via an aperture, wherein the light detected by the light detection means is limited to light from a predetermined light-gathering region of the sample by passing the transmitted light, reflected light, or total reflected light from the sample through the aperture, and the light detection means has at least two detectors, an array detector and a single-element detector, and the above-described Cassegrain microscope mirror, in which at least one of the light-gathering optical elements includes an off-axis reflecting light-gathering mirror, is provided on the optical path of the light detection means so as to receive the light to be detected through the through-hole, wherein the array detector is positioned at the first point, and the single-element detector is positioned at the second point.

[0021] In the above-described microscope, a detection-side Cassegrain mirror is provided between the sample and the aperture to collect transmitted light, reflected light, or total reflected light from the sample, the sample stage is configured to be movable in a direction perpendicular to the central axis of the detection-side Cassegrain mirror, and the microscope preferably performs mapping measurements of a predetermined measurement area of ​​the sample by sequentially changing the light-collecting area of ​​the sample by moving the sample stage, detecting transmitted light, reflected light, or total reflected light from the light-collecting area, and acquiring spectral data of the light-collecting area.

[0022] Alternatively, in the above-described microscope, a detection-side Cassegrain mirror for collecting transmitted or reflected light from the sample and a detection-side scanning mirror for reflecting light from the detection-side Cassegrain mirror toward the aperture are provided between the sample and the aperture, and the orientation of the reflective surface of the detection-side scanning mirror with respect to the incident direction from the detection-side Cassegrain mirror is variable, thereby allowing the light-gathering region of the sample detected by the light detection means to be changed, and it is preferable that the microscope detects transmitted or reflected light from the light-gathering region which is sequentially changed by the detection-side scanning mirror, and acquires spectral data of the light-gathering region to perform mapping measurement of a predetermined measurement area of ​​the sample.

[0023] In the above-described microscope, it is preferable that the microscope comprises an illumination-side scanning mirror for guiding light from the light irradiation means to the sample, and an illumination-side Cassegrain mirror for focusing the light from the illumination-side scanning mirror to irradiate a predetermined irradiation area on the sample, wherein the illumination-side scanning mirror has a variable orientation of its reflective surface with respect to the incident direction from the light irradiation means, thereby allowing the irradiation area to be sequentially changed to match the focusing area.

[0024] Alternatively, in the above-described microscope, a detection-side Cassegrain mirror for collecting total reflected light from the sample and a detection-side scanning mirror for reflecting total reflected light from the detection-side Cassegrain mirror toward the aperture are provided between the sample and the aperture, wherein the detection-side Cassegrain mirror has a crystal element with a high refractive index for contact with the sample, and the light supplied from the light irradiation means to the detection-side Cassegrain mirror, which also serves as the irradiation-side Cassegrain mirror, is focused on the crystal element to irradiate a predetermined irradiation area within the contact surface with the sample at an incident angle greater than or equal to a critical angle, wherein the orientation of the reflective surface of the detection-side scanning mirror with respect to the incident direction from the detection-side Cassegrain mirror is variable, thereby allowing the light-gathering area within the contact surface detected by the light detection means to be changed, and the microscope preferably performs mapping measurements of minute parts within the contact surface by detecting the total reflected light from the light-gathering area which is sequentially changed by the detection-side scanning mirror and acquiring spectral data of the light-gathering area.

[0025] In the above-described microscope, it is preferable that the irradiating side scanning mirror is provided for guiding light from the light irradiation means to the detection side Cassegrain mirror, and that the orientation of the reflective surface of the irradiating side scanning mirror is variable with respect to the incident direction from the light irradiation means, thereby enabling the irradiation area of ​​light in minute parts within the contact surface to be sequentially changed to match the light-gathering area.

[0026] Using a Cassegrain mirror for microscopes with the above configuration, it is possible to switch between different focusing optical systems (Cassegrain mirror and other focusing optical systems) depending on the measurement conditions, such as the microscope's instrument configuration, and to achieve space savings. This is because, for Cassegrain mirrors, the primary mirror (concave mirror) remains fixed, and only the smaller secondary mirror (convex mirror) is moved, allowing the secondary mirror to be replaced by another focusing optical element. As a result, the space required for switching between focusing optical systems for microscopes does not increase significantly. Furthermore, switching between focusing optical systems only requires changing the operating position of a secondary mirror moving member, such as a slider or rotating member, during measurement, enabling fast and smooth operation.

[0027] For example, by adopting the Cassegrain mirror for microscopes of the present invention as the configuration of the focusing optical system in front of the detector, it is possible to smoothly select the optimal focusing optical system (an elliptical concave mirror for the single-element detector and a Cassegrain mirror for the array detector) for the single-element detector and array detector used for measurement, respectively, without increasing the size of the microscope equipped with both a single-element detector and an array detector. Furthermore, the space required for switching the focusing optical system for the detector does not increase. Moreover, if the array detector is placed at the first point determined by the Cassegrain mirror for the detector and the single-element detector is placed at the second point, during measurement, it is only necessary to switch the operating position of the secondary mirror moving member according to the selected detector. As a result, it is possible to achieve both single-point measurement and imaging measurement with a single microscope, that is, to achieve both high-precision measurement of minute areas and high-speed imaging measurement.

[0028] (A) is a cross-sectional view and (B) is a longitudinal section showing the state in which the Cassegrain mirror for the detector of the first embodiment is used to focus light onto a linear array detector (Cassegrain mirror mode). (A) is a cross-sectional view and (B) is a longitudinal section showing the state in which the Cassegrain mirror for the detector is used to focus light onto a single-element detector (elliptic concave mirror mode). (A) is a cross-sectional view and (B) is a longitudinal section showing a modified example of the Cassegrain mirror for the detector, in which light is focused onto a third detector. (B) is a diagram showing another modified example of the Cassegrain mirror for the detector, in which the positional relationship between the Cassegrain mirror for the detector and the first to fourth detectors is shown. (A) is a perspective view for explaining the structure and operation of the slider in the Cassegrain mirror for the detector of the second embodiment, where (A) shows the upper limit position of the slider and (B) shows the lower limit position of the slider. (A) is a schematic diagram of the Cassegrain mirror for the detector of the first embodiment, and (B) is a schematic diagram of the parabolic mirror mode of the Cassegrain mirror for the detector of the third embodiment. (A) is a schematic diagram of the parabolic mirror mode of the Cassegrain mirror for the detector of the fourth embodiment, and (B) is a schematic diagram of the Cassegrain mirror mode. This is a longitudinal cross-sectional view showing the state in which the Cassegrain mirror for the detector of the fifth embodiment is used to focus light onto a linear array detector (focusing lens mode). This is a schematic diagram of the Cassegrain mirror for the sample of the sixth embodiment. This is a diagram showing the optical path when performing transmission measurement using a microscope equipped with the Cassegrain mirror for the detector of the first embodiment. This is a diagram showing the optical path when performing ATR measurement using the microscope. This is a diagram showing an example of a focusing region specified in (A) for single-point measurement, (B) for multi-point measurement, and (C) for imaging measurement. (A) is a configuration diagram of a conventional focusing optical system for single-point measurement, (B) is a configuration diagram of a conventional focusing optical system for imaging measurement, and (C) is a diagram showing a configuration in which a Cassegrain mirror is used in the focusing optical system and a switching mirror switches the optical path to two types of detectors.

[0029] Hereinafter, based on the drawings, a first embodiment will be described in which the Cassegrain mirror for microscope according to the present invention is applied to a Cassegrain mirror for detector. The Cassegrain mirror for detector 100 is used in a microscope to focus the light to be detected onto either the detector 60 or 70. Figures 1 to 3 show a cross-sectional view of the Cassegrain mirror for detector at the top and a longitudinal cross-sectional view at the bottom, respectively. For convenience, the light to be detected onto the Cassegrain mirror for detector 100 travels in the horizontal direction (X-axis), and the side with the entrance 12 is considered the front. The X-axis direction is the depth direction of the Cassegrain mirror for detector 100, the Y-axis direction is the width direction, and the Z-axis direction is the height direction.

[0030] As shown in Figure 1, the detector Cassegrain mirror 100 comprises a housing 10, a primary mirror 20 fixed inside the front of the housing 10, a slider 30 held so as to be movable in the vertical direction relative to the housing 10, two elements of a focusing optical system (a secondary mirror 40 and an elliptical concave mirror 50) attached to the slider 30, and a lifting motor (not shown) as a drive unit for raising and lowering the slider 30.

[0031] The primary mirror 20 has a concave reflective surface and a through-hole 22 in its center, and is coaxial with the entrance port 12 of the housing 10. The light to be detected is incident along the central axis of this through-hole 22. The direction of movement of the slider 30 is perpendicular to the central axis of the through-hole 22, which in this case is the vertical direction.

[0032] The secondary mirror 40 has a convex reflective surface opposite to the concave reflective surface of the primary mirror 20. The secondary mirror 40 and the elliptic concave mirror 50 are aligned in the vertical direction of the slider 30, with the secondary mirror 40 at the top and the elliptic concave mirror 50 at the bottom. The elliptic concave mirror 50 may be replaced with another off-axis reflecting condenser (for example, a parabolic mirror), as will be described later. The slider 30 is movable to at least two positions: a first position where the secondary mirror 40 is positioned on the central axis of the through hole 22 (as shown in Figure 1), and a second position where the elliptic concave mirror 50 is positioned on the central axis of the through hole 22 (as shown in Figure 2, where the secondary mirror 40 is off-axis). Two or more off-axis reflecting condensers may be arranged on the slider 30 together with the secondary mirror 40, so that the respective condensing optical elements are swapped and positioned on the central axis by the positioning operation of the slider 30.

[0033] In the first position shown in Figure 1, that is, at the lower limit of the slider 30, the light to be detected entering the through-hole 22 is reflected by the secondary mirror 40 and then the primary mirror 20 in that order, and an image is formed at a first point on the extension of the central axis of the through-hole 22. This is the light-gathering action of the Cassegrain mirror consisting of the primary mirror 20 and the secondary mirror 40. This first point is outside the output port 14 of the housing 10, and the array elements of the linear array detector 60 (linear array MCT detector) are arranged at this first point.

[0034] In the second position shown in Figure 2, that is, the upper limit position of the slider 30, the light to be detected that enters the through-hole 22 is reflected by the elliptic concave mirror 50 in a direction different from the central axis of the through-hole 22 (in this case, the Y-axis direction), and an image is formed at a second point in this reflection direction. This is a light-gathering action by the elliptic concave mirror 50 alone, without the primary mirror 20. This second point is outside the output port 16 of the housing 10, and a single element of the single-element detector 70 (single-element MCT detector) is positioned at this second point.

[0035] Furthermore, at the lower limit position (first position) of the slider 30, the lower end of the slider 30 contacts the floor surface of the housing 10, thus ensuring the reproducibility of the lower limit position of the slider 30. On the other hand, a magnet 18 is attached to the ceiling surface of the housing 10 to attract the upper end of the slider 30, and the magnet 18 ensures the reproducibility of the upper limit position (second position) of the slider 30.

[0036] Figure 3 shows a modified example of a Cassegrain mirror for a detector. The Cassegrain mirror 200 for a detector in Figure 3 has a posture changing mechanism 80 that changes the orientation of the reflective surface of the elliptical concave mirror 50, which is not provided in the Cassegrain mirror 100 for a detector in Figure 2. In the modified example, the elliptical concave mirror 50 is attached to the slider 30 via the posture changing mechanism 80. This posture changing mechanism 80 may be configured to allow the elliptical concave mirror 50 to rotate around the central axis of the through hole 22, for example, or it may be composed of a turntable and a rotation motor.

[0037] In the example shown in Figure 3, with the slider 30 in the second position, the attitude changing means 80 rotates the elliptical concave mirror 50 90 degrees around its central axis, causing the reflected light from the elliptical concave mirror 50 to travel in a direction different from both the direction of extension of the central axis of the through hole 22 in Figure 1 and the reflection direction based on the orientation of the elliptical concave mirror 50 in Figure 2. As a result, the reflected light from the elliptical concave mirror 50 forms an image at a third point different from the first and second points (in this case, the ceiling surface of the housing 10 directly above the elliptical concave mirror 50). A single element of a single-element detector 90 of a different type from the single-element detector 70 (for example, a room-temperature type semiconductor element) may be placed at this third point.

[0038] Furthermore, in the case where four different types of detectors (No. 1 to No. 4) are provided in the microscope, as in the Cassegrain mirror 300 for another modified detector shown in Figure 4, focusing on detector No. 1 is done using the secondary mirror 40 and primary mirror 20 shown in Figure 1, and focusing on the other detectors No. 2 to No. 4 is done using the elliptical concave mirror 50, which can be rotated in three directions (left, right, and up when viewed from the incident side) using the attitude changing means 80 shown in Figure 3.

[0039] Next, using Figure 5, the structure of the slider 30A in the Cassegrain mirror 400 for the detector of the second embodiment and the operation of the slider 30A will be explained. This slider 30A is configured to move up and down within the housing, similar to the slider 30 in Figure 1, but the slider 30A has a crank shape so that the mounting positions of the secondary mirror 40 and the elliptical concave mirror 50 are offset from each other in the X-axis direction. By configuring the slider 30A in this way, the positions of the Cassegrain mirror (primary mirror 20, secondary mirror 40) and the elliptical concave mirror 50 can be aligned with the positional relationship (especially the distance between them in the X direction) of the linear array detector 60 and the single-element detector 70.

[0040] In addition, although the case of sliders 30 and 30A that move back and forth has been described as the moving members for the secondary mirror, a configuration may also be adopted in which the secondary mirror 40, the elliptic concave mirror 50, the parabolic mirrors 50A and 50B (described later), and the condensing lens 50C are positioned by swapping positions on the central axis using a revolving-type rotatable disc. In this case, it is preferable to hold the rotating disc rotatably in the housing 10 so that the axis of rotation of the rotating disc is parallel to the central axis of the through hole 22.

[0041] Figure 6(A) is a schematic diagram of the Cassegrain mirror 100 for the detector in use according to the first embodiment, and Figure 6(B) is a schematic diagram of the Cassegrain mirror 600 for the detector in use according to the third embodiment. In the Cassegrain mirror 600 for the detector in Figure 6(B), a pair of parabolic mirrors 50A and 50B are used as off-axis reflection focusing mirrors instead of the elliptical concave mirror 50.

[0042] Since the elliptic concave mirror 50 has foci in front of and behind the mirror, in the optical system of the Cassegrain mirror 100 for the detector using the elliptic concave mirror 50, as shown in Figure 6(A), an aperture 540 is placed at the front focal point of the elliptic concave mirror 50, and the light-receiving surface of the single-element detector 70 is placed at the rear focal point of the elliptic concave mirror 50.

[0043] On the other hand, there are generally two ways in which the parabolic mirror 50A is used. The first is to bring parallel light into the parabolic mirror 50A and focus the reflected light at the focal point of the parabolic mirror 50A. The second is to bring light that is spreading in the direction of propagation into the parabolic mirror 50A and extract the reflected light as parallel light.

[0044] Therefore, in the Cassegrain mirror 600 for a detector according to the third embodiment, as shown in FIG. 6(B), the first parabolic mirror 50A is arranged on the slider 30 together with the secondary mirror 40, and the second parabolic mirror 50B is arranged in front of the single-element detector 70. The position of the first parabolic mirror 50A changes as the slider 30 moves, while the second parabolic mirror 50B is fixed at a certain position with respect to the microscope, and the positional relationship with the single-element detector 70 is constant. FIG. 6(B) shows a state (parabolic mirror mode) in which the first parabolic mirror 50A is located on the central axis of the through-hole 22. The detection target light that spreads in the traveling direction from the aperture 540 enters the Cassegrain mirror 600 for a detector, is reflected by the first parabolic mirror 50A to become parallel light, and then travels to the second parabolic mirror 50B. The parallel light is reflected by the second parabolic mirror 50B and forms an image at the focal point of the parabolic mirror 50B in the reflection direction. The element surface of the single-element detector 70 is located at the focal point of the parabolic mirror 50B.

[0045] Further, FIG. 7 is a schematic diagram of the usage state of the Cassegrain mirror 700 for a detector according to the fourth embodiment. FIG. 7(A) shows the "parabolic mirror mode", and FIG. 7(B) shows the "Cassegrain mirror mode". The Cassegrain mirror 700 for a detector also uses a set of parabolic mirrors 50A and 50B as an off-axis reflection condenser, similar to the third embodiment, but the optical arrangement method is different.

[0046] In the detector Cassegrain mirror 700, as shown in Figure 7(A), the first parabolic mirror 50A is positioned between the aperture 540 and the through-hole 22 of the primary mirror 20, and the second parabolic mirror 50B is positioned on the slider 30 together with the secondary mirror 40. The first parabolic mirror 50A is fixed in a constant position relative to the microscope, and its positional relationship with the aperture 540 is constant. The position of the second parabolic mirror 50B changes as the slider 30 moves. The light to be detected, spreading out in the direction of propagation from the aperture 540, is reflected by the first parabolic mirror 50A to become parallel light, which then travels through the through-hole 22 of the primary mirror 20 to the second parabolic mirror 50B. The parallel light is reflected by the second parabolic mirror 50B and forms an image at the focal point of the parabolic mirror 50B in the direction of reflection. The element plane of the single-element detector 70 is located at the focal point of the parabolic mirror 50B. In Cassegrain mirror mode, as shown in Figure 7(B), parallel light from the first parabolic mirror 50A is imaged onto the element plane of the linear array detector 60 by the secondary mirror 40 and the primary mirror 20.

[0047] Here, we will explain the case of spectral measurement using a near-infrared light source or a laser light source as the light source for a microscope. When an objective lens is used in the focusing optical system for the sample (near-infrared light measurement), or when a laser is used as the light source, the measurement accuracy can be improved by using a focusing lens in the focusing optical system for the detector.

[0048] In near-infrared light measurement, since the wavelength range to be measured is narrower than that in mid-infrared measurement, the influence of chromatic aberration is reduced. Usually, an objective lens is used as the condenser optical system for the sample. When condensing the near-infrared light from the sample with the objective lens, the energy at the central part of the cross-section of the light beam is the highest. When a Cassegrain mirror is used for the condenser optical system of the detector for such a light beam, the central part is specularly reflected by the secondary mirror and lost, so most of the light is lost. Therefore, in the case of a single-element detector, by using an elliptical concave mirror (or a parabolic mirror) for the detector, such loss can be avoided, and the signal-to-noise ratio (S / N) is improved. Also, in the case of a linear array detector, by attaching a condenser lens to the condenser optical system of the detector, the S / N is improved. Note that the same applies to the case of measurement with a laser light source. This is because the laser has a small beam diameter, and if it is incident on the Cassegrain mirror with the original diameter, most of the energy will be lost due to specular reflection by the secondary mirror. Also, since the laser has a narrow wavelength range, the influence of chromatic aberration is almost negligible.

[0049] From the above, in order for the microscope to be applicable not only to mid-infrared light source measurement but also to near-infrared light source measurement and spectral measurement with a laser light source, for the condenser optical system for the sample (such as the upper Cassegrain mirror above the sample stage), it is advisable to use a turret or the like so that it can be switched from the Cassegrain mirror to the objective lens (condenser lens).

[0050] Fig. 8 shows the Cassegrain mirror 800 for the detector of the fifth embodiment. In this Cassegrain mirror 800 for the detector, three elements, namely the secondary mirror 40 of the Cassegrain mirror, the elliptical concave mirror 50 (or parabolic mirror), and the condenser lens 50C, are arranged on the slider 30B, and are configured such that any one of the condenser optical systems can be selected by moving the slider 30B. When switching so that the condenser lens 50C is on the central axis of the through-hole 22, if the imaging position of the light by the condenser lens 50C does not coincide with the imaging position by the Cassegrain mirror (primary mirror 20, secondary mirror 40), for example, the position of the linear array detector 60 in the X direction may be adjusted.

[0051] Figure 9 shows the sample Cassegrain mirror 900 of the sixth embodiment. Unlike the embodiments described above, this describes the case in which the microscope Cassegrain mirror of the present invention is applied to the upper Cassegrain mirror close to the sample stage 522.

[0052] A slider 30 is used as the secondary mirror moving member, but a rotating member may be used to create a revolving-type switching mechanism. The slider 30 is equipped with the secondary mirror 40 of the Cassegrain mirror and a focusing lens (objective lens 50D), and one of the focusing optical systems is selected by moving the slider 30. When the secondary mirror 40 is selected, as shown in Figure 9(A), light from the light irradiation means is reflected by the reflection measuring mirror 534 and enters the sample Cassegrain mirror 900. The primary mirror 20 and secondary mirror 40 then illuminate a minute area of ​​the sample on the sample stage 522. The primary mirror 20 and secondary mirror 40 also collect light from the minute area of ​​the sample and send it to the detector via the detection-side scanning mirror 526 and aperture 540. When the objective lens 50D is selected, as shown in Figure 9(B), light from the light irradiation means is reflected by the reflection measuring mirror 534 and enters the sample Cassegrain mirror 900, where the objective lens 50D illuminates a minute area of ​​the sample on the sample stage 522. The objective lens 50D also collects light from the minute area of ​​the sample and sends it to the detector via the detection-side scanning mirror 526 and aperture 540. Although not shown in the figure, a similar switching mechanism with the objective lens can be constructed for a Cassegrain mirror with an ATR prism. Furthermore, by reversing the optical arrangement, a switching mechanism with the objective lens can also be constructed for the lower Cassegrain mirror.

[0053] Hereafter, a microscope 500 to which the detector Cassegrain mirror 100 shown in the first embodiment is applied will be described using Figures 10 and 11. The microscope 500 is an infrared microscope configured by connecting a Fourier transform infrared spectrophotometer (hereinafter referred to as FTIR) 520. The FTIR 520 has a built-in infrared light source and a Michelson interferometer, and is responsible for supplying the interference wave of infrared light output from the interferometer to the microscope 500, and corresponds to the light irradiation means of the present invention.

[0054] The microscope 500 consists of a micro-optical unit 530, an aperture 540, a Cassegrain mirror 100 for the detector, a linear array detector 60, a single-element detector 70, and various reflecting mirrors. The micro-optical unit 530 is the part that performs transmission, reflection, or total internal reflection measurements of a minute area of ​​the sample using infrared light.

[0055] <Spectrum Measurement Using a Single-Element Detector> First, we will explain single-point measurement using a single-element detector 70, using the optical system for transmission measurement as an example. The switching mirror 512 in Figure 10 guides infrared light from the FTIR 520 to the optical path for transmission measurement (in the order of reflecting mirror 514, transmission measuring mirror 516, and lower Cassegrain mirror 518). The lower Cassegrain mirror 518 for the sample (corresponding to the illumination-side Cassegrain mirror) focuses the infrared light reflected from the transmission measuring mirror 516 and illuminates a predetermined area of ​​the sample placed on the sample stage 522 from below. The transmitted light from the sample is extracted and focused by the upper Cassegrain mirror 524 for the sample (corresponding to the detection-side Cassegrain mirror) and reflected by the detection-side scanning mirror 526 located above. An aperture 540 is placed at the imaging position behind the upper Cassegrain mirror 524 to cut out light (stray light, etc.) generated from areas other than the light-gathering region on the sample and to detect only the light that has passed through the desired light-gathering region. Light passing through the aperture 540 is imaged at the single-element detector 70 (second point) by the detector Cassegrain mirror 100 with the slider in the second position. The second point is located at the confocal point of the aperture 540. The electrical signal corresponding to the amount of light received by the single-element detector 70 is Fourier transformed in the signal processing means to obtain infrared spectral data.

[0056] The magnification of the Cassegrain mirror for the sample should be selected from the range of 4 to 100x. The aperture size of aperture 540 indicates the size of the light-gathering area on the sample. Even with the same aperture, the size of the measurement area on the sample changes depending on the magnification of the Cassegrain mirrors 518 and 524 used with it. Even if the magnification of the Cassegrain mirrors 518 and 524 for the sample is fixed, it is desirable that the aperture size and shape be adjustable so that the measurement area on the sample can be adjusted. For example, multiple apertures of different shapes and aperture sizes may be prepared, and the desired shape and aperture size may be selected and used according to the measurement conditions. An aperture equipped with a mechanism that allows the shape and size of the aperture to be changed may also be used.

[0057] In this embodiment, the single-element detector 70 is combined with an elliptical concave mirror 50 with good light-gathering efficiency so that it can receive weak infrared light that has passed through the aperture 540 without any leakage. When using the single-element detector 70, it is possible to prevent light loss by changing the magnification of the Cassegrain mirrors 518 and 524 for the sample.

[0058] In Figure 10, by rotating the reflective surface of the switching mirror 512 by 90 degrees, the infrared light from the FTIR 520 can be guided to the optical path for reflection measurement (in the order of reflecting mirror 532, reflection measuring mirror 534, and upper Cassegrain mirror 524). In this case, the upper Cassegrain mirror 524 serves both the function of the illumination-side Cassegrain mirror and the detection-side Cassegrain mirror.

[0059] <Spectral Measurement Using a Linear Array Detector> Next, using the optical system of ATR measurement as an example, mapping measurement (high-speed imaging) using a linear array detector 60 will be explained. The linear array detector 60 has multiple detection elements arranged in a line, and can measure the spectra of multiple measurement positions within the light-gathering area on the sample at once, thus shortening the time required for mapping measurement.

[0060] In the ATR measurement optical system shown in Figure 11, the reflective surface of the switching mirror 512 is rotated 90 degrees so that the switching mirror 512 guides infrared light into the optical path for reflection measurement (reflecting mirror 532, reflection measuring mirror 534, and ATR prism-equipped Cassegrain mirror 523). The ATR prism-equipped Cassegrain mirror 523, which is a high refractive index crystal element, serves two functions: irradiating a predetermined focusing region within the contact surface between the sample and the ATR prism at an incident angle greater than the critical angle (function of the irradiating Cassegrain mirror), and focusing the total reflected light from the sample again with the Cassegrain mirror via the ATR prism (function of the detecting Cassegrain mirror). The reflection measuring mirror 534 is positioned in half of the region divided by a boundary line passing through the optical axis on a cross section perpendicular to the optical axis connecting the ATR prism-equipped Cassegrain mirror 523 and the detecting scan mirror 526, and is not positioned in the other half of the region, so it is also called a half mirror. In other words, in total internal reflection measurement, infrared light from the reflecting mirror 532 is reflected by the reflecting measuring mirror 534 and travels towards the Cassegrain mirror 523 with an ATR prism, illuminating the sample. The total internal reflection light from the contact surface between the sample and the ATR prism is then focused and travels through the space where the reflecting measuring mirror 534 is not located, to the detection-side scanning mirror 526.

[0061] An aperture 540 is placed at the imaging position behind the Cassegrain mirror 523 with an ATR prism to cut out light (stray light, etc.) that originates outside the predetermined focusing region and to detect only the totally reflected light from the desired focusing region. Light that passes through the aperture 540 is imaged at the linear array detector 60 (first point) by the detector Cassegrain mirror 100 with the slider in the first position. The first point is located at the confocal point of the aperture 540. The electrical signals corresponding to the amount of light received by each detection element of the linear array detector 60 are Fourier transformed in the signal processing means to obtain infrared spectral data.

[0062] The overall magnification of the ATR prism-equipped Cassegrain mirror 523 should be selected from the range of 4 to 100x. The aperture size of the aperture 540 corresponds to the size of the contact area where total reflected light is to be focused. Even if the aperture is the same, the size of the contact area where total reflected light is focused will change depending on the magnification of the ATR prism-equipped Cassegrain mirror 523 that it is combined with. Even if the magnification of the ATR prism-equipped Cassegrain mirror 523 is fixed, it is desirable that the aperture size and shape be changeable so that the desired contact area can be adjusted. For example, multiple apertures of different shapes and aperture sizes may be prepared, and the desired shape and aperture size may be selected and used according to the measurement conditions. An aperture equipped with a mechanism that allows the shape and size of the aperture to be changed may also be used.

[0063] This section will explain in detail the mapping measurement of a predetermined range on a sample using the infrared microscope 500 with these configurations. The infrared microscope 500 enables spectral measurement at high magnification, but when it is desired to capture the entire sample, a mapping measurement is performed to capture the entire sample or a specific range uniformly.

[0064] One method involves mapping measurement accompanied by the operation of a sample stage 522 equipped with an electronically controlled automatic stage. In this method, the sample is placed on the automatic stage of the sample stage 522, and the focusing area on the sample is sequentially changed by moving the automatic stage. Here, the detector Cassegrain mirror 100 may select a single-element detector 70, and spectral measurements for each focusing area may be performed using the single-element detector 70 with an aperture 540 corresponding to the single-element detector 70. Alternatively, the detector Cassegrain mirror 100 may select a linear array detector 60, and spectral measurements may be performed simultaneously on multiple points within the focusing area using an aperture 540 corresponding to the linear array detector 60. By these methods, spectral data of the focusing area can be acquired, and mapping data for a predetermined range of the sample can be created.

[0065] The second method involves fixing the sample stage 522 and operating the detection-side scanning mirror 526 to sequentially change the light-gathering area on the sample, acquiring spectral data of the light-gathering area, and creating mapping data for a predetermined range of the sample. In this case as well, either the single-element detector 70 or the linear array detector 60 can be used. In this embodiment, the switching mirror 512 for switching between transmission measurement and reflection measurement (including total reflection measurement) also serves as the irradiation-side scanning mirror. In other words, the switching mirror 512 has both a function to switch between transmission measurement and reflection measurement by rotating its reflective surface by 90 degrees, and a scanning function that sequentially moves the irradiation area on the sample by further finely controlling the orientation of its reflective surface with a controller in each of the 90-degree rotation positions (for both transmission and reflection measurement).

[0066] Furthermore, the orientation of the reflective surface of the detection-side scanning mirror 526 is adjusted so that only light from a specific focusing region on the sample is directed towards the aperture 540. By controlling the orientation of the reflective surface of the detection-side scanning mirror 526 with a controller, the focusing region on the sample that aligns with the aperture 540 can be moved. By changing the orientation of the reflective surface of the switching mirror (irradiation-side scanning mirror) 512 to move the irradiation region on the sample, the orientation of the reflective surface of the detection-side scanning mirror 526 is also changed so that the focusing region moves in the same way as the irradiation region. For all of these moving positions of the focusing region and irradiation region, by repeatedly measuring the spectrum of the focusing region using either the single-element detector 70 or the linear array detector 60, a certain range on the sample can be measured using two-dimensional mapping.

[0067] As described above, by synchronizing the operation of the switching mirror (irradiation-side scanning mirror) 512 with the operation of the detection-side scanning mirror 526, when a wider X-Y plane range (here, the surface on which the sample stage is placed is referred to as the X-Y plane) is set as the mapping measurement range, high-energy spectral data can be acquired across the entire mapping measurement range. In other words, two-dimensional mapping measurement becomes possible based on high-quality spectral data acquired over a wider X-Y plane range.

[0068] Furthermore, even when the switching mirror (irradiation-side scanning mirror) 512 is fixed and only the detection-side scanning mirror 526 is operated, spectral data with a sufficiently high energy value can be acquired in a certain X-Y plane range close to the center of the irradiation light, so two-dimensional mapping measurement can be performed.

[0069] Even when performing total internal reflection measurements on a sample using the ATR prism-equipped Cassegrain mirror 523 instead of the upper Cassegrain mirror 524, two-dimensional mapping measurements can be performed without moving the sample stage 522 by using the detection-side scan mirror 526, or by using both the detection-side scan mirror 526 and the switching mirror (irradiation-side scan mirror) 512. In other words, in total internal reflection measurements, the operation of the detection-side scan mirror 526 sequentially changes the focusing region within the contact surface between the ATR prism and the sample. Furthermore, by adding the operation of the switching mirror (irradiation-side scan mirror) 512, the irradiation region within the contact surface between the ATR prism and the sample is sequentially changed to match the focusing region.

[0070] By using the linear array detector 60 to acquire spectral data from multiple points within a light-gathering region simultaneously, and repeating this process for each moving light-gathering region, two-dimensional mapping measurements can be performed at high speed. This type of mapping measurement is specifically called "imaging measurement."

[0071] In this embodiment, the linear array detector 60 is combined with Cassegrain mirrors (secondary mirror 40 and primary mirror 20) that have good imaging performance and low chromatic aberration. In imaging measurements performed in this configuration, it is possible to ensure that the same level of light-gathering performance (imaging performance, chromatic aberration, and light-gathering efficiency) is achieved from one end of the linear array element to the other.

[0072] <Effects of this embodiment> By using the microscope 500 of this embodiment, the measurement wavelength range is very wide, from 1 to 16 μm, and the sample size is wide, from a few μm to several hundred μm. It is possible to appropriately switch between single-point measurement and imaging measurement, and with a single microscope 500, it is possible to achieve both high-precision measurement of minute areas and high-speed imaging measurement.

[0073] In this case, without increasing the size of the microscope 500, it is possible to select the optimal focusing optical system (elliptic concave mirror and Cassegrain mirror) for the single-element detector 70 and linear array detector 60 used for each measurement. This is because, for the Cassegrain mirror, the primary mirror 20 is fixed while only the secondary mirror 40 is moved, and the secondary mirror 40 is replaced by the elliptic concave mirror 50, so the space required for switching the focusing optical system for the detector does not increase.

[0074] Furthermore, the secondary mirror 40 and the elliptical concave mirror 50 are fixed to the same slider 30, and as the slider 30 moves up and down, the secondary mirror 40 and the elliptical concave mirror 50 are swapped. The reproducibility of the swapping positions of the secondary mirror 40 and the elliptical concave mirror 50 is ensured in the vertical downward direction by the lower end of the slider 30 contacting the floor surface, and in the vertical upward direction by the upper end of the slider 30 being attracted to the magnet 18 on the ceiling surface.

[0075] Furthermore, the Cassegrain mirror for microscopes of the present invention is not limited to the embodiments described above, and can be applied to Cassegrain mirrors installed at any position along the optical path from the light irradiation means (FTIR 520) to the light detection means (linear array detector 60, single-element detector 70, etc.) of the microscope. For example, as shown in Figure 9, it can also be applied to a Cassegrain mirror for a sample, enabling smooth switching and space saving when it is desired to switch the focusing optical system according to measurement conditions such as the instrument configuration of the microscope.

[0076] 10 Housing 20 Primary mirror 22 Through hole 30, 30A, 30B Slider (secondary mirror moving member) 40 Secondary mirror 50 Elliptical concave mirror (off-axis reflection focusing mirror) 50A First parabolic mirror 50B Second parabolic mirror 50C Focusing lens 50D Objective lens (focusing lens) 60 Linear array detector 70 Single-element detector 80 Attitude changing means 90 Room temperature type single-element detector 100, 200, 300, 400, 600, 700, 800 Cassegrain mirror for detector 500 Microscope 512 Switching mirror that also serves as the illumination-side scanning mirror 516 Transmission measuring mirror 518 Lower Cassegrain mirror (illumination-side Cassegrain mirror) 520 FTIR (light irradiation means) 522 Sample stage 523 Cassegrain mirror with ATR prism (serves as both the illumination and detection Cassegrain mirrors) 524 Upper Cassegrain mirror (serves as both the illumination and detection Cassegrain mirrors) 526 Detection side scanning mirror 534 Reflectance measuring mirror 540 Aperture 900 Cassegrain mirror for sample

Claims

1. A Cassegrain mirror for a microscope, comprising: a housing; a primary mirror fixed to the housing and having a concave reflective surface and a through hole provided in the center of the concave reflective surface; a secondary mirror positioned on the central axis of the through hole and having a convex reflective surface opposite to the concave reflective surface; a secondary mirror moving member for moving the secondary mirror between a position on the central axis and a position off the central axis; at least one light-gathering optical element attached to the secondary mirror moving member together with the secondary mirror; and a drive unit for driving the secondary mirror moving member, wherein the at least one light-gathering optical element is positioned on the central axis when the secondary mirror is off the central axis, and when the secondary mirror is on the central axis by the secondary mirror moving member, the Cassegrain mirror consisting of the primary mirror and the secondary mirror is configured to gather light incident on the through hole. A Cassegrain mirror for a microscope, characterized in that when the sub-mirror moving member positions any of the at least one of the light-gathering optical elements on the central axis, the light incident on the through-hole is focused by the one light-gathering optical element without passing through the primary mirror.

2. The Cassegrain mirror for a microscope according to claim 1, wherein the at least one light-gathering optical element includes an off-axis reflecting condenser, and when the secondary mirror is on the central axis by the secondary mirror moving member, the light incident on the through hole is reflected by the secondary mirror and the primary mirror in that order to form an image at a first point on the extension of the central axis, and when the off-axis reflecting condenser is on the central axis by the secondary mirror moving member, the light incident on the through hole is reflected by the off-axis reflecting condenser in a reflection direction different from the central axis to form an image at a second point on that reflection direction.

3. The Cassegrain microscope for a microscope according to claim 2, characterized in that the off-axis reflecting focusing mirror is attached to the secondary mirror moving member via a posture changing means that changes the orientation of the reflecting surface of the off-axis reflecting focusing mirror, and when the off-axis reflecting focusing mirror is on the central axis, the posture changing means is configured to image the reflected light from the off-axis reflecting focusing mirror at a third point on a reflection direction different from both the central axis and the reflection direction.

4. The Cassegrain mirror for a microscope according to claim 1, wherein the at least one light-gathering optical element includes a gathering lens, and when the secondary mirror is on the central axis by the secondary mirror moving member, the light incident on the through hole is reflected in the order of the secondary mirror and the primary mirror to form an image at a first point on the extension of the central axis, and when the gathering lens is on the central axis by the secondary mirror moving member, the light incident on the through hole is formed by the gathering lens at any point on the extension of the central axis.

5. The Cassegrain microscope for a microscope according to claim 1, characterized in that the secondary mirror moving member is a slider held in the housing so as to be movable in one direction, and the direction of movement is perpendicular to the central axis of the through hole.

6. The Cassegrain microscope for a microscope according to claim 1, characterized in that the secondary mirror moving member is a rotating member held in the housing, and the axis of rotation of the rotating member is parallel to the central axis of the through hole.

7. A microscope for measuring the spectrum of a minute portion of a sample placed on a sample stage, comprising: a light irradiation means for irradiating the sample with light; and a light detection means for detecting transmitted light, reflected light, or total reflected light from the sample via an aperture, wherein the measurement is performed by restricting the light detected by the light detection means to light from a predetermined light-gathering area of ​​the sample by passing the transmitted light, reflected light, or total reflected light from the sample through the aperture, and a Cassegrain mirror for microscopes according to any one of claims 1 to 6 is provided in the optical path from the light irradiation means to the light detection means.

8. A microscope for measuring the spectrum of a minute portion of a sample placed on a sample stage, comprising: a light irradiation means for irradiating the sample with light; and a light detection means for detecting transmitted light, reflected light, or total reflected light from the sample via an aperture, wherein the light detected by the light detection means is limited to light from a predetermined light-gathering area of ​​the sample by passing the transmitted light, reflected light, or total reflected light from the sample through the aperture, and the measurement is performed accordingly, wherein the light detection means has at least two detectors, an array detector and a single-element detector, and a Cassegrain mirror for microscopes according to claim 2 or 3 is provided on the optical path of the light detection means so as to receive the light to be detected through the through-hole, the array detector is positioned at the first point, and the single-element detector is positioned at the second point.

9. A detection-side Cassegrain mirror is provided between the sample and the aperture to collect transmitted light, reflected light, or total reflected light from the sample; the sample stage is configured to be movable in a direction perpendicular to the central axis of the detection-side Cassegrain mirror; and the microscope sequentially changes the light-gathering area of ​​the sample by moving the sample stage, detects transmitted light, reflected light, or total reflected light from the light-gathering area, and acquires spectral data of the light-gathering area to perform mapping measurement of a predetermined measurement area of ​​the sample, as described in claim 7.

10. The microscope according to claim 7, wherein a detection-side Cassegrain mirror for collecting transmitted or reflected light from the sample and a detection-side scanning mirror for reflecting light from the detection-side Cassegrain mirror toward the aperture are provided between the sample and the aperture, the orientation of the reflective surface of the detection-side scanning mirror with respect to the incident direction from the detection-side Cassegrain mirror is variable, thereby allowing the light-collecting region of the sample detected by the light detection means to be changed, and the microscope detects transmitted or reflected light from the light-collecting region which is sequentially changed by the detection-side scanning mirror, and acquires spectral data of the light-collecting region to perform mapping measurement of a predetermined measurement area of ​​the sample.

11. The microscope according to claim 10, comprising: an illumination-side scanning mirror for guiding light from the light irradiation means to a sample; and an illumination-side Cassegrain mirror for focusing the light from the illumination-side scanning mirror to irradiate a predetermined irradiation area on the sample, wherein the orientation of the reflective surface of the illumination-side scanning mirror is variable with respect to the incident direction from the light irradiation means, thereby enabling the irradiation area to be sequentially changed to match the focusing area.

12. Between the sample and the aperture, there is a detection-side Cassegrain mirror that collects total reflected light from the sample and a detection-side scanning mirror that reflects the total reflected light from the detection-side Cassegrain mirror toward the aperture, wherein the detection-side Cassegrain mirror has a crystal element with a high refractive index for contact with the sample, and the light supplied to the detection-side Cassegrain mirror, which also serves as an illumination-side Cassegrain mirror, is focused on the crystal element to illuminate a predetermined irradiation area within the contact surface with the sample at an incident angle greater than or equal to a critical angle, wherein the orientation of the reflective surface of the detection-side scanning mirror with respect to the incident direction from the detection-side Cassegrain mirror is variable, thereby allowing the light-collecting area within the contact surface detected by the light-detection means to be changed, and the microscope detects the total reflected light from the light-collecting area which is sequentially changed by the detection-side scanning mirror, and acquires spectral data of the light-collecting area to perform mapping measurements of minute parts within the contact surface, characterized in that the microscope is as described in 7.

13. The microscope according to claim 12, further comprising an illumination-side scanning mirror for guiding light from the light irradiation means to the detection-side Cassegrain mirror, wherein the orientation of the reflective surface of the illumination-side scanning mirror is variable with respect to the incident direction from the light irradiation means, thereby enabling sequential changes to the light irradiation area in minute portions within the contact surface to match the light-gathering area.

Images