Sample stage and microscope

Abstract

The present invention provides a sample stage with a built-in pressure sensor for attenuated total reflectance (ATR) measurements, wherein a detachable plate can be smoothly attached and detached. The sample stage comprises: a stage surface member 4 having an opening 2; and a detachable plate 6 held by the stage surface member 4 so as to close the opening 2. Pressure sensors 8 are arranged on the stage surface member 4 at three locations along the edge of the opening 2, a sample is placed on the surface of the detachable plate 6, and three projections 18 are formed at positions corresponding to the pressure sensors 8 on the side surface of the plate or the rear surface of the plate. Each pressure sensor 8 is brought into a sensing state by placing the projections 18 of the detachable plate 6 on the pressure sensors 8 of the stage surface member 4, and each pressure sensor 8 is brought into a non-sensing state by placing the projections 18 on a portion 22A other than the pressure sensors among the edge of the opening 2, with the detachable plate 6 being rotated by a prescribed angle.

Description

Sample stage and microscope

[0001] The present invention relates to an improvement in a specimen stage in a microscope.

[0002] For example, an infrared microscope is a device that irradiates a sample placed on a movable stage with infrared light, collects and detects transmitted light, reflected light, or total reflected light from a small area on the sample, and obtains its infrared spectrum.

[0003] Total internal reflection (ATR) measurements using an infrared microscope involve placing a prism (crystal element) with a higher refractive index than the sample in close contact with the sample, irradiating measurement light from the prism at an angle of incidence that causes total reflection at the boundary surface, and detecting the spectrum of the total reflected light to measure the absorption characteristics of the sample. Therefore, ATR measurements require that the sample and prism (crystal element) be in close contact with each other. The XY stage on which the sample is placed is raised, pressing the sample against the prism located above the XY stage. Since applying too much pressure risks damaging the prism, a pressure sensor is used to measure the pressure on the sample and prevent excessive pressure from being applied.

[0004] There are two possible positions for incorporating the pressure sensor: on the prism side or on the sample stage side. If the pressure sensor is incorporated on the prism side, the pressure sensor on the prism side will deform when the sample is pressed against the prism, causing a slight change in the position of the prism in the prism holding structure. This means that the optical system will move, which may change the angle of incidence on the prism, cause the sample position and the focal position to no longer match, and result in measurements not being performed with the optimal optical system.

[0005] On the other hand, if a pressure sensor is built into the stage, there is no need to worry about the optimal optical system being disrupted even if the sample is pressed against the prism. For example, Patent Document 1 provides a detailed explanation of an ATR measurement method using a sample stage with a built-in pressure sensor, using Figure 5.

[0006] Japanese Patent Application Laid-Open No. 2001-147379

[0007] In recent years, there has been a demand for a single infrared microscope that can switch between transmission measurement, reflection measurement, and ATR measurement, and some microscopes are designed with a replaceable sample placement plate for each measurement mode. The sample stage of such an infrared microscope typically consists of a stage surface member with a central opening and a detachable plate that is held by the stage surface member and covers the opening.

[0008] The inventors have used a detachable plate with a built-in pressure sensor as an ATR measurement plate. An electrical cable from the pressure sensor extends from the detachable plate and can be inserted into or removed from a connection part on the infrared microscope body. When performing transmission measurements, the ATR measurement plate is replaced with a transmission measurement plate having an opening that transmits infrared light. Each time such a replacement is performed, the cable of the ATR measurement plate must be inserted or removed, which poses a problem of cumbersome installation and removal of the detachable plate.

[0009] Therefore, in developing a sample stage with a built-in pressure sensor compatible with ATR measurement, the inventors aimed to create a stage that would enable smooth attachment and detachment of the detachable plate.

[0010] That is, the sample stage for a microscope of the present invention comprises a stage surface member having an opening, and a detachable plate held on the stage surface member so as to cover the opening, wherein the stage surface member has pressure sensors arranged at multiple locations along the edge of the opening, and the detachable plate has a plate surface on which a sample is placed, and multiple convex portions formed on the side or back of the plate at positions corresponding to the pressure sensors, and the stage surface member is characterized by having a sensing holding position in which the detachable plate is held by placing the convex portions on the pressure sensors, thereby putting the pressure sensors into a sensing state, and a non-sensing holding position in which the detachable plate is held by placing the convex portions on parts of the edge of the opening other than the pressure sensors in an attitude in which the detachable plate is rotated a predetermined angle relative to the sensing holding position, thereby putting the pressure sensors into a non-sensing state.

[0011] Using a sample stage with this configuration, the built-in pressure sensor enables detection of external forces, such as the pressure applied to the sample on the removable plate. If the pressure sensor were built into the removable plate, attaching or detaching the plate would require the attachment or detachment of a signal line connecting the pressure sensor to the control unit of the measurement device main body, making the process complicated. However, by incorporating the pressure sensor into the stage surface member as in the present invention, the removable plate does not include a pressure sensor, eliminating the need to attach or detach the pressure sensor's signal line, making the attachment or detachment of the removable plate smoother. Furthermore, the pressure sensor's sensing state can be switched between its non-sensing state simply by changing the holding position of the removable plate. For measurements that do not require pressure sensor sensing, such as transmission or reflection measurements, the non-sensing state can be quickly switched to the non-sensing state, and this also protects the pressure sensor. Furthermore, a microscope according to the present invention is characterized by including the above-described sample stage.

[0012] 8A is a schematic stereoscopic view of the sample stage of the first embodiment, (B) is a plan view, and (C) is a longitudinal cross-sectional view. A stereoscopic view showing the configuration of the sample stage in more detail. A plan view showing characteristic parts of the sample stage of FIG. 2. A longitudinal cross-sectional view showing characteristic parts of the sample stage of FIG. 2. A longitudinal cross-sectional view showing the mounting state of the pressure sensor of FIG. 2. A stereoscopic view showing an automatic XY stage, which is a specific example of the sample stage of FIG. 2, and various plates that can be mounted thereon. A plan view showing the state in which a transmission measurement plate is mounted on the sample stage of FIG. 2. A diagram showing the optical path when performing transmission measurement using a microscope equipped with the sample stage of FIG. 1. A diagram showing the optical path when performing ATR measurement using the microscope of FIG. 8.

[0013] A first embodiment of a sample stage for a microscope according to the present invention will now be described with reference to the drawings. Figures 1(A) and 1(B) schematically show a sample stage 10 according to this embodiment.

[0014] The sample stage 10 comprises a stage surface member 4 having an opening 2 in the center, and a detachable plate 6 held by the stage surface member 4 so as to cover the opening 2. In this example, the opening 2 and the detachable plate 6 are circular and of approximately the same size. Figure 1(B) is a plan view of these components.

[0015] The stage surface member 4 has pressure sensors 8 evenly spaced at three locations along the edge of the opening 2. A plate surface 12 of the detachable plate 6 is the surface on which a sample is placed, and three protrusions 18 are formed on the plate side surface 14 or the plate back surface 16 at positions corresponding to the pressure sensors 8. Figure 1(C) is a longitudinal cross-sectional view of these.

[0016] When the removable plate 6 is held on the stage surface member 4 with the protrusion 18 placed on the pressure sensor 8, the pressure sensor 8 enters a sensing state. This holding position is called the sensing holding position (left side of FIG. 1C ). Furthermore, when the removable plate 6 is rotated a predetermined angle with respect to the sensing holding position and the protrusion 18 is placed on a portion 22 of the edge of the opening 2 other than the pressure sensor, the pressure sensor 8 enters a non-sensing state. This holding position is called the non-sensing holding position (right side of FIG. 1C ).

[0017] Next, a specific example of the configuration of the sample stage 10 will be described with reference to Figures 2 to 4. Figure 2 is an enlarged view of the protrusion 18 of the detachable plate 6 and the opening 2 of the stage surface member 4.

[0018] The detachable plate 6 is circular, and the thickness around its entire periphery is thinner than the thickness at the center. However, the thickness of the periphery is not uniform; there are three slightly thicker portions formed at 120-degree intervals along the periphery, which are the protrusions 18.

[0019] Two steps are formed around the entire periphery of the edge of the opening 2 in the stage surface member 4. The first step surface 22A is lower than the stage surface, and the second step surface 22B is even lower. These step surfaces 22A and 22B are not formed continuously around the entire periphery of the edge, but are discontinuous at three locations spaced 120 degrees apart along the edge of the opening 2. At these three locations, there are openings to storage spaces for the pressure sensors 8, and each storage space is formed inside the stage surface member 4.

[0020] The outer diameter of the first-step step surface 22A is approximately the same as the outer diameter of the detachable plate 6, and the outer peripheral surface of the detachable plate 6 is detachably fitted inside the wall surface of the first-step step surface 22A. Furthermore, a step surface 22C of intermediate height between the first-step and second-step step surfaces 22A, 22B is formed in the portion of the first-step step surface 22A adjacent to the storage space. The formation range (dimension A) of the intermediate step surface 22C on the left and right sides, including the storage space, is slightly wider than the width (dimension B) of the protrusion 18.

[0021] The first step surface 22A or the second step surface 22B corresponds to the "portion 22 of the edge of the opening 2 other than the pressure sensor" shown in FIG. 1(C).

[0022] Here, pressure sensors 8 are provided in the storage space such that the tips of the cantilever arms 8A that make up the pressure sensors 8 protrude into the opening 2. The positional relationship between these pressure sensors 8, the respective step surfaces 22A to 22C, and the convex portion 18 will be explained using Figures 3 and 4. Figure 3 is a plan view of the periphery of the pressure sensors 8, and the tips of the pressure sensors 8 provided in the storage space of the stage surface member 4 protrude into the opening 2, but only to the extent of the first step surface 22A and the intermediate step surface 22C, and not to the extent of the second step surface 22B.

[0023] 4 shows a cross section taken along the edge of the opening shown in FIG. 3, and FIG. 5 shows a cross section taken along the longitudinal direction of the pressure sensor 8. As shown in FIG.

[0024] 4(A) shows the positional relationship with the pressure sensor 8 before the detachable plate 6 is attached to the sensing holding position, and FIG. 4(B) shows the positional relationship with the pressure sensor 8 after attachment. The height of the upper surface of the pressure sensor 8 is equal to or slightly lower than the height of the first step surface 22A. When the detachable plate 6 is attached, the lower surface of the convex portion 18 of the detachable plate 6 comes into contact with the upper surface of the tip of the pressure sensor 8, and the weight of the detachable plate 6 is applied to the pressure sensor 8, causing the pressure sensor 8 to enter a sensing state. Even if the tip of the pressure sensor 8 bends downward, the convex portion 18 does not come into contact with the first step surface 22A because there are intermediate step surfaces 22C on the left and right of the pressure sensor 8.

[0025] Figure 4(C) shows the positional relationship after the removable plate 6 has been attached to the non-sensing holding position. The removable plate 6 in Figure 4(A) is rotated a certain angle around a central axis perpendicular to the plate surface, and then the removable plate 6 is attached. In this state, the underside of the protrusion 18 of the removable plate 6 contacts the first step surface 22A, so the portion of the edge of the removable plate 6 where the protrusion 18 is not formed does not come into contact with the pressure sensor 8. Therefore, the non-sensing state of the pressure sensor 8 is maintained.

[0026] FIG. 5 is a longitudinal cross-sectional view of the pressure sensor 8. The pressure sensor 8 includes a cantilever arm 8A and a strain gauge 8B that detects bending of the cantilever arm 8A. The base end of the cantilever arm 8A is fixed to the back of the stage surface member 4 by a fixing screw 8C, located deep within the storage space of the stage surface member 4. The tip of the cantilever arm 8A protrudes into the opening 2 and is positioned to receive the protrusion 18 of the detachable plate 6. The strain gauge 8B attached to the surface of the cantilever arm 8A can detect the vertical displacement of the arm tip as arm deflection with high sensitivity. Furthermore, since the sensor can be constructed thinner than pressure sensors using other methods, it offers significant advantages when used on sample stages, where thinness is preferred. For example, a thinner sample stage 10 can increase the movable range of the sample stage 10 in the Z-axis direction (the optical axis direction of the microscope), thereby increasing the working distance.

[0027] FIG. 6 is an external view of an automated XY stage incorporating the sample stage of this embodiment. In addition to the detachable plate 6, a common plate 6A for ATR / transmission measurements is also shown. The surface of this common plate 6A includes an area for total reflection measurement that does not transmit measurement light and an area for transmission measurement (opening 6B) that transmits measurement light. The aperture 6B for transmission measurement does not necessarily need to be located in the center of the plate surface. Except for the presence or absence of this aperture, the common plate 6A has the same configuration as the ATR measurement plate 6. When attached to the sensing holding position of the aperture 2 of the stage surface member 4, the pressure sensor 8 can be placed in a sensing state. By using the above-described common plate 6A, one plate can be used for both total reflection measurement and transmission measurement. This eliminates the need to replace the detachable plate when switching from total reflection measurement to transmission measurement in the microscope, reducing the workload and enabling seamless measurement changes. Furthermore, in total reflection measurements, by holding the detachable plate in the sensing position, the microscope can perform measurements using the detection information from the pressure sensor, and in transmission measurements, by holding the detachable plate in the non-sensing position, unnecessary load is not placed on the pressure sensor, thereby protecting the pressure sensor during transmission measurements.

[0028] 6 also shows a transmission measurement plate 32 and a common holder 34 as other detachable plates not intended for ATR measurement. The transmission measurement plate 32 has an opening 32A for transmission measurement. The common holder 34 is a holder that can be used in common between, for example, an infrared microscope and other microscopes (such as a laser Raman spectrophotometer or a microscopic ultraviolet-visible-near-infrared spectrophotometer), and the common holder 34 also has an opening 34A for transmission measurement. The outer diameters of the transmission measurement plate 32 and the common holder 34 are slightly smaller than those of the ATR measurement plate 6 and the common plate 6A, and no protrusions are formed on the side or back surfaces of the plates.

[0029] 7 is a plan view showing the state in which the transmission measurement plate 32 is attached to the stage surface member 4. The back surface of the transmission measurement plate 32 is placed on the second step surface 22B of the opening 2 of the stage surface member 4, and it can be seen that the transmission measurement plate 32 does not come into contact with the pressure sensor 8. Therefore, when attaching the transmission measurement plate 32, there is no need to specify a holding position such as a sensing holding position or a non-sensing holding position, and the transmission measurement plate 32 can be attached at any angle, allowing the pressure sensor 8 to be kept in a non-sensing state. The common holder 34 is also attached in the same manner as the transmission measurement plate 32.

[0030] All of the various detachable holders shown in FIG. 6 can be used to perform reflection measurements by placing a sample on the detachable holder. Reflection measurements are not limited to areas without an opening, and can also be performed when a sample is located in an opening. The outer diameter of the transmission measurement plate 32 may be the same as that of the ATR measurement plate 6 or the common plate 6A. Even if the outer diameter is changed, the transmission measurement plate 32 does not have a convex portion 18 formed thereon. Therefore, the rear surface of the enlarged transmission measurement plate 32 is placed on the first step surface 22A of the opening 2 of the stage surface member 4. This also prevents the transmission measurement plate 32 from deflecting the pressure sensor 8. The outer diameter of the common holder 34 can be expanded in the same way as the transmission measurement plate 32.

[0031] The sample stage 10 configured in this embodiment incorporates a pressure sensor 8, making it possible to detect external forces, such as pressure applied to a sample on the removable plate 6. If the pressure sensor 8 were incorporated into the removable plate 6, attaching or detaching the removable plate 6 would require the attachment or detachment of a signal line connecting the pressure sensor 8 to the control unit of the measurement device main body, making the process complicated. However, if the pressure sensor 8 is incorporated into the stage surface member 4 as in this embodiment, the removable plate 6 does not include the pressure sensor 8. This eliminates the need to attach or detach the signal line for the pressure sensor 8, making the attachment or detachment of the removable plate 6 smoother. Furthermore, the pressure sensor 8 can be switched between a sensing state and a non-sensing state simply by changing the holding position of the removable plate 6. For measurements that do not require sensing by the pressure sensor 8, such as transmission or reflection measurements, the pressure sensor 8 can be quickly switched to a non-sensing state, and the non-sensing state also protects the pressure sensor 8. Furthermore, if the removable plate 6 is held in the sensing position, the pressure sensor 8 can detect the presence or absence of a sample on the removable plate 6. For example, a message can be automatically displayed on a monitor or the like to warn the user that a sample has been left on the detachable plate 6 .

[0032] 8 and 9, a microscope 500 employing the sample stage 10 shown in the first embodiment will be described. The microscope 500 is an infrared microscope configured by connecting a Fourier transform infrared spectrophotometer (hereinafter referred to as FTIR) 520. The FTIR 520 incorporates an infrared light source and a Michelson interferometer, and serves to supply the microscope 500 with an interference wave of infrared light output from the interferometer, and corresponds to the light irradiation means of the present invention.

[0033] The microscope 500 is composed of a microscopic optical unit 530, an aperture 540, a single-element detector 550, and various reflecting mirrors. The microscopic optical unit 530 is a part that performs transmission, reflection, or total reflection measurement of a minute area of ​​a sample using infrared light. The detector is not limited to the single-element detector 550, and other detectors such as a linear array detector 560 can also be selected as appropriate.

[0034] <Transmission Measurement> First, transmission measurement will be described. A detachable plate for transmission measurement, such as the common plate 6A, transmission measurement plate 32, or common holder 34 shown in FIG. 6 , is attached to the stage surface member 4 of the sample stage 10. In the case of the common plate 6A, it is attached in a non-sensing holding position. In the case of the transmission measurement plate 32 or the common holder 34, the pressure sensor 8 of the sample stage 10 can remain in a non-sensing state regardless of the angle at which they are attached. Then, a measurement target is placed on the surface of these plates. For example, transmission measurement can be performed by placing a rectangular plate carrying a sample in the opening 6B of the common plate 6A, or by placing the sample directly on the opening 6B for a sample larger than the opening 6B. For measurements using infrared light, a rectangular plate made of an infrared-transmitting material such as potassium bromide or diamond is used.

[0035] The switching mirror 512 in FIG. 8 guides the infrared light from the FTIR 520 to the optical path for transmission measurement (in the order of the reflecting mirror 514, the transmission measurement mirror 516, and the 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 measurement mirror 516 and illuminates a predetermined area of ​​the sample placed on the sample stage 10 from below. The light transmitted through 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 above. An aperture 540 is placed at the imaging position behind the upper Cassegrain mirror 524 to cut out light (such as stray light) generated from areas other than the light-focusing area on the sample and detect only the light transmitted through the desired light-focusing area. Light passing through the opening of aperture 540 passes through a light-collecting element for the detector (not shown) and forms an image on single-element detector 550. An electrical signal corresponding to the amount of light received by single-element detector 550 is Fourier transformed by signal processing means to become infrared spectrum data.

[0036] The magnification of the sample Cassegrain mirror may be selected from a range of 4x to 100x. The opening size of the aperture 540 indicates the size of the light-collecting area on the sample. Even if the aperture is the same, the size of the measurement area on the sample varies depending on the magnification of the sample Cassegrain mirrors 518, 524 that are combined. Even if the magnification of the sample Cassegrain mirrors 518, 524 is fixed, it is preferable that the size and shape of the opening be changeable so that the measurement area on the sample can be adjusted. For example, multiple apertures with different shapes and opening sizes may be prepared, and the desired shape and size of the aperture may be selected and used depending on the measurement conditions. An aperture equipped with a mechanism that allows the shape and size of the opening to be changed may also be used.

[0037] <Switching to Reflection Measurement> Next, a brief description will be given of a method for switching from the optical configuration for transmission measurement to the optical configuration for reflection measurement shown in Fig. 8. In reflection measurement, the switching mirror 512 is rotated 90 degrees so that the infrared light from the FTIR 520 is guided to the optical path for reflection measurement (in the order of reflecting mirror 532, reflection measurement mirror 534, and upper Cassegrain mirror 524).

[0038] In reflection measurement, the upper sample Cassegrain mirror 524 (corresponding to the illumination-side Cassegrain mirror) focuses the infrared light reflected from the reflection measurement mirror 534 and illuminates a predetermined area of ​​the sample placed on the sample stage 10 from above. The light reflected from the sample is again extracted and focused by the upper sample Cassegrain mirror 524 (which also serves as the detection-side Cassegrain mirror) and directed to the detection-side scanning mirror 526 above. The components from the detection-side scanning mirror 526 onwards are the same as those for transmission measurement.

[0039] Here, the reflection measurement mirror 534 is arranged in half of the area divided by a boundary line passing through the optical axis on a cross section perpendicular to the optical axis connecting the upper Cassegrain mirror 524 and the detection-side scan mirror 526, and is not arranged in the other half, so it is also called a half mirror. In reflection measurement, infrared light from the reflecting mirror 532 is reflected by the reflection measurement mirror 534, proceeds toward the upper Cassegrain mirror 524, and irradiates the sample. The reflected light from the sample is collected by the upper Cassegrain mirror 524, and then travels through the space where the reflection measurement mirror 534 is not located to proceed to the detection-side scan mirror 526.

[0040] <ATR Measurement> Next, ATR measurement will be described. Mapping measurement (high-speed imaging) in ATR measurement will also be described. By selecting a linear array detector 560, in which multiple detection elements are arranged in a row, it is possible to simultaneously measure spectra at multiple measurement positions within the focused region on the sample, thereby shortening the time required for mapping measurement.

[0041] When switching from transmission measurement to ATR measurement, the operator can quickly and smoothly replace the transmission measurement plate 32 on the sample stage 10 with the detachable plate 6 for ATR measurement. Simply attaching the detachable plate 6 at the sensing holding position puts the pressure sensor 8 into sensing mode. Furthermore, if a common plate 6A is used in transmission measurement, simply rotating the common plate 6A by a predetermined angle and moving it to the sensing holding position is sufficient. In this way, switching between ATR measurement, reflection measurement, and transmission measurement becomes smooth, allowing for seamless changes in measurement method depending on the measurement target.

[0042] Then, the object to be measured is placed on the surface of these plates (on the portion without an opening in the case of the common plate 6A). Also, the revolver above the sample stage 10 is rotated to select the Cassegrain mirror 523 with the ATR prism 522 as the upper Cassegrain mirror.

[0043] In the ATR measurement optical system shown in Figure 9, the reflective surface of the switching mirror 512 is rotated 90 degrees so that the switching mirror 512 directs infrared light to the optical path for reflection measurement (reflecting mirror 532, reflection measurement mirror 534, and Cassegrain mirror 523 with ATR prism). The Cassegrain mirror 523, which has an ATR prism 522, a high-refractive-index crystal element, serves two functions: irradiating a predetermined focusing area within the interface between the sample and the ATR prism 522 at an incident angle equal to or greater than the critical angle (function of the illumination-side Cassegrain mirror), and also focusing the total reflected light from the sample again on the Cassegrain mirror via the ATR prism (function of the detection-side Cassegrain mirror). The reflection measurement mirror 534 is located in one half of the area divided by the boundary line passing through the optical axis on a cross section perpendicular to the optical axis connecting the Cassegrain mirror 523 with ATR prism and the detection-side scanning mirror 526, and is therefore not located in the other half. Therefore, it is also called a half mirror. That is, in total reflection measurement, infrared light from reflecting mirror 532 is reflected by reflecting measurement mirror 534, travels toward Cassegrain mirror with ATR prism 523, and irradiates the sample. Then, the total reflected light from the contact surface between the sample and ATR prism 522 is collected and travels toward detection-side scanning mirror 526 through a space where reflecting measurement mirror 534 is not located.

[0044] In order to cut out light (stray light, etc.) generated from areas other than the designated light-collecting area and detect only the total reflected light from the desired light-collecting area, an aperture 540 is placed at the imaging position behind the Cassegrain mirror 523 with an ATR prism. Light that passes through the opening of the aperture 540 forms an image on a linear array detector 560 via a light-collecting element for the detector (not shown). An electrical signal corresponding to the amount of light received by each detecting element of the linear array detector 560 is Fourier transformed by a signal processing means to become infrared spectrum data.

[0045] The total magnification of the Cassegrain mirror with ATR prism 523 may be selected from the range of 4 to 100 times. The opening size of the aperture 540 corresponds to the size of the contact area where the total reflected light is to be focused. Even if the aperture is the same, the size of the contact area where the total reflected light is to be focused varies depending on the magnification of the Cassegrain mirror with ATR prism 523 to be combined. Even if the magnification of the Cassegrain mirror with ATR prism 523 is fixed, it is preferable that the size and shape of the opening be changeable so that the desired contact area can be adjusted. For example, multiple apertures with different shapes and opening sizes may be prepared, and an aperture with the desired shape and opening size may be selected and used depending on the measurement conditions. An aperture equipped with a mechanism that allows the shape and size of the opening to be changed may also be used.

[0046] Here, the measurement function at a constant contact pressure in ATR measurement will be explained. The infrared microscope of Figure 9 is further provided with a driving means 610 that can drive the sample stage 10 in the X-, Y-, and Z-axis directions relative to the ATR prism 522, a control means 612 that controls the operation of this driving means 610, an operation means 614 that controls the relative drive of the sample stage 10 and the ATR prism 522, and a storage means 616. A detection signal from the pressure sensor 8 built into the sample stage 10 is sent to the control means 612 through a signal cable.

[0047] The infrared microscope 500 can determine whether the ATR prism 522 is in contact with the sample based on the detection signal from the pressure sensor 8 read by the control means 612. Furthermore, the pressure between the sample and the ATR prism 522 has a significant effect on the results of the ATR measurement. For this reason, once a total reflection absorption spectrum has been measured in an actual measurement, the data on the contact pressure between the sample and the ATR prism 522 at the very first measurement is stored in the storage means 616. When further measurements are to be performed on the same sample, when the operator determines another measurement site, the control means 612 automatically operates the stage so that the sample and the ATR prism 522 come into contact with each other at the same contact pressure data as the stored data.

[0048] In this way, when performing ATR measurements at multiple points on a sample, the control means 612 monitors the contact pressure measured by the pressure sensor at each measurement point, drives the sample stage 10 relative to the ATR prism 522 in the Z-axis direction using the driving means 610, and stops the driving means 610 when the contact pressure reaches a specific pressure, thereby measuring the total reflection spectrum at each measurement point at a constant contact pressure.

[0049] In this way, even when multiple measurements are performed on the same sample, it is possible to reduce variations in the contact state between the sample and the ATR prism 522 at each measurement point, making it possible to obtain highly reliable data even when performing linear measurements and mapping measurements.

[0050] A detailed description will be given of mapping measurement of a predetermined area on a sample using the infrared microscope 500 configured as described above. The infrared microscope 500 enables spectrum measurement at high magnification, but when it is desired to capture the entire sample to be measured, mapping measurement is performed to capture the entire sample or a specific area in a unified manner.

[0051] The first method involves mapping measurement involving the operation of the sample stage 10, which has an electronically controlled automatic stage. In this method, a sample is placed on the automatic stage of the sample stage 10, and the light-collecting region on the sample is sequentially changed by moving the automatic stage. Here, a single-element detector 550 may be selected as the detector, and an aperture 540 corresponding to the single-element detector 550 may be used to perform spectral measurement for each light-collecting region. Alternatively, a linear array detector 560 may be selected, and an aperture 540 corresponding to the linear array detector 560 may be used to simultaneously perform spectral measurement of multiple points within the light-collecting region. These methods can be used to acquire spectral data of the light-collecting region and create mapping data for a predetermined range of the sample.

[0052] The second method involves moving the detection-side scanning mirror 526 while keeping the sample stage 10 fixed, thereby sequentially changing the light-focusing area on the sample, acquiring spectral data on the light-focusing area, and creating mapping data for a specified range of the sample. In this case, either the single-element detector 550 or the linear array detector 560 can be used. In this embodiment, the switching mirror 512, which switches between transmission and reflection measurements (including total reflection measurements), also serves as the illumination-side scanning mirror. In other words, the switching mirror 512 has two functions: a function to switch between transmission and reflection measurements by rotating the reflective surface 90 degrees, and a scanning function to sequentially move the illumination area on the sample by minutely controlling the orientation of the reflective surface with a controller at each 90-degree rotation (both transmission and reflection measurements).

[0053] The orientation of the reflective surface of the detection-side scanning mirror 526 is adjusted so that only light from a specific light-collecting region on the sample is directed toward the opening of the aperture 540. By controlling the orientation of the reflective surface of this detection-side scanning mirror 526 with a controller, the light-collecting region on the sample can be moved to match the opening of the aperture 540. The orientation of the reflective surface of the switching mirror (illumination-side scanning mirror) 512 is changed to move the illumination region on the sample, and at the same time, the orientation of the reflective surface of the detection-side scanning mirror 526 is also changed so that the light-collecting region moves in the same direction as the illumination region. Repeated spectral measurements of the light-collecting region for all of these moving positions of the light-collecting region and illumination region using either the single-element detector 550 or the linear array detector 560 enable two-dimensional mapping measurements of a certain area on the sample.

[0054] As described above, by synchronizing the operation of the switching mirror (illumination-side scanning mirror) 512 with the operation of the detection-side scanning mirror 526, when a wider XY plane range (here, the mounting surface of the sample stage is referred to as the XY plane) is set as the mapping measurement range, it is possible to acquire spectral data with high energy values ​​throughout the entire mapping measurement range. In other words, two-dimensional mapping measurement based on high-quality spectral data acquired over a wider XY plane range becomes possible.

[0055] Even when the switching mirror (illumination-side scanning mirror) 512 is fixed and only the detection-side scanning mirror 526 is operated, spectral data with a relatively high energy value can be acquired within a certain range of the XY plane near the center of the illumination light, making it possible to perform two-dimensional mapping measurement.

[0056] Even when the ATR prism-equipped Cassegrain mirror 523 is used instead of the upper Cassegrain mirror 524 to measure the total reflection of a sample, two-dimensional mapping measurement can be performed without moving the sample stage 10 by using the detection-side scanning mirror 526 or by using both the detection-side scanning mirror 526 and the switching mirror (illumination-side scanning mirror) 512. That is, in total reflection measurement, the light-collecting area within the contact surface between the ATR prism and the sample is sequentially changed by the operation of the detection-side scanning mirror 526. Furthermore, by adding the operation of the switching mirror (illumination-side scanning mirror) 512, the irradiation area within the contact surface between the ATR prism and the sample is sequentially changed to match the light-collecting area.

[0057] By using the linear array detector 560 to simultaneously acquire spectral data from multiple points within the light collection area, and repeating this process for each moving light collection area, two-dimensional mapping measurement can be performed at high speed. This type of mapping measurement is particularly called "imaging measurement."

[0058] 2 Opening 4 Stage surface member 6 Detachable plate (ATR measurement plate) 6A Detachable plate (common plate) 6B, 32A, 34A Opening for transmission measurement 8 Pressure sensor 8A Cantilever arm 8B Strain gauge 10 Sample stage 18 Convex portion 22 Portion of edge of opening other than pressure sensor 22A First step surface 22B Second step surface 22C Intermediate step surface 32 Plate for transmission measurement 34 Common holder 500 Infrared microscope (microscope) 512 Switchable mirror also serving as irradiation side scanning mirror 516 Transmission measurement mirror 518 Lower Cassegrain mirror (irradiation side Cassegrain mirror) 520 FTIR (light irradiation means) 522 ATR prism (total reflection crystal element) 523 Cassegrain mirror with ATR prism (serves as both the irradiation side and detection side Cassegrain mirror) 524 Upper Cassegrain mirror (serves as both the irradiation side and detection side Cassegrain mirror) 526 Detection side scanning mirror 534 Reflection measurement mirror 540 Aperture 550 Single element detector (light detection means) 560 Linear array detector (light detection means) 610 Driving means 612 Control means

Claims

1. A sample stage for a microscope comprising: a stage surface member having an opening; and a detachable plate held on the stage surface member so as to cover the opening, wherein the stage surface member has pressure sensors arranged at multiple locations along the edge of the opening, the detachable plate having: a plate surface on which a sample is placed; and a plurality of protrusions formed on the side or back of the plate at positions corresponding to the pressure sensors, the stage surface member having: a sensing holding position in which the detachable plate is held by placing the protrusions on the pressure sensors, thereby putting the pressure sensors into a sensing state; and a non-sensing holding position in which the detachable plate is held in an attitude in which the detachable plate is rotated a predetermined angle relative to the sensing holding position, by placing the protrusions on parts of the edge of the opening other than the pressure sensors, thereby putting the pressure sensors into a non-sensing state.

2. A sample stage according to claim 1, wherein the plate surface of the detachable plate includes an area for total reflection measurement that does not transmit measurement light, and an area for transmission measurement that transmits measurement light.

3. A sample stage as described in claim 1, further comprising another detachable plate that does not have the convex portion, said another detachable plate being configured to be held in the sensing and non-sensing holding positions in place of the detachable plate that has the convex portion, and because it does not have the convex portion, a portion along the edge of the back surface of the plate is configured to rest on a portion of the edge of the opening other than the pressure sensor in either holding position, thereby maintaining the pressure sensor in a non-sensing state.

4. A sample stage as described in claim 1, characterized in that the pressure sensor has a cantilever arm and a strain gauge that detects bending of the cantilever arm, and the cantilever arm has a base end fixed to the back side of the stage surface member and a tip end that protrudes into the opening and is positioned to receive the protrusion of the detachable plate.

5. A microscope compatible with total reflection measurement, comprising: a total internal reflection crystal element; a sample stage according to any one of claims 1 to 4; drive means for driving the sample stage relative to the total internal reflection crystal element in X- and Y-axis directions parallel to the stage surface and in a Z-axis direction perpendicular to the stage surface; and control means for controlling the operation of the drive means, wherein the pressure sensor detects the contact pressure between the sample on the detachable plate and the total internal reflection crystal element, and the control means, when performing total reflection measurement at multiple points on the sample, drives the sample stage relative to the total internal reflection crystal element in the Z-axis direction while monitoring the contact pressure measured by the pressure sensor at each measurement point, and stops the drive means when the contact pressure reaches a specific pressure, thereby enabling the microscope to measure the total reflection spectrum at each measurement point at a constant contact pressure.

6. A microscope for measuring the spectrum of a minute portion of a sample, comprising: a sample stage according to any one of claims 1 to 4; 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 microscope is configured to perform measurements by limiting the light detected by the light detection means to only light from a predetermined light-focusing region of the sample by passing the transmitted light, reflected light, or total reflected light from the sample through the aperture.

7. A microscope according to claim 6, characterized in that a detection-side Cassegrain mirror that collects transmitted light, reflected light, or total reflected light from the sample is provided between the sample and the aperture, 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-collecting area of ​​the sample by moving the sample stage, detects transmitted light, reflected light, or total reflected light from the light-collecting area, and obtains spectral data of the light-collecting area, thereby performing mapping measurements of a predetermined measurement area of ​​the sample.

8. A microscope according to claim 6, characterized in that: between the sample and the aperture, there are provided a detection-side Cassegrain mirror that focuses transmitted or reflected light from the sample, and a detection-side scanning mirror that reflects light from the detection-side Cassegrain mirror toward the aperture; the detection-side scanning mirror has a reflective surface whose orientation relative to the incident direction from the detection-side Cassegrain mirror is variable, thereby making it possible to change the focused area of ​​the sample detected by the light detection means; and the microscope detects transmitted or reflected light from the focused area that is sequentially changed by the detection-side scanning mirror, and obtains spectral data of the focused area, thereby performing mapping measurements of a predetermined measurement area of ​​the sample.

9. A microscope according to claim 8, comprising an illumination-side scanning mirror for guiding light from the light illumination means to the sample, and an illumination-side Cassegrain mirror for converging the light from the illumination-side scanning mirror and illuminating a predetermined illumination area on the sample, wherein the illumination-side scanning mirror has a reflective surface whose orientation is variable relative to the direction of incidence from the light illumination means, thereby making it possible to sequentially change the illumination area to match the light-collecting area.

10. The microscope according to claim 6, characterized in that: between the sample and the aperture, there are provided a detection-side Cassegrain mirror that collects the 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; the detection-side Cassegrain mirror has a high-refractive index total reflection crystal element that is brought into contact with the sample, and light from the light irradiation means that is supplied to the detection-side Cassegrain mirror, which also serves as the irradiation-side Cassegrain mirror, is collected on the total reflection crystal element and is configured to irradiate a predetermined irradiation area within the contact surface with the sample at an incident angle equal to or greater than the critical angle; the detection-side scanning mirror has a variable reflecting surface orientation relative to the direction of incidence from the detection-side Cassegrain mirror, thereby making it possible to change the light-collecting area within the contact surface that is detected by the light detection means; and the microscope detects the total reflected light from the light-collecting area that is sequentially changed by the detection-side scanning mirror and obtains spectral data of the light-collecting area, thereby performing mapping measurements of minute areas within the contact surface.

11. A microscope as described in claim 10, further comprising an illumination-side scanning mirror for guiding light from the light illumination means to the detection-side Cassegrain mirror, wherein the orientation of the reflection surface of the illumination-side scanning mirror is variable relative to the incident direction from the light illumination means, thereby enabling the light illumination area at a minute location within the contact surface to be sequentially changed to match the light collection area.

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