Raman microscope

Abstract

To provide a Raman microscope capable of easily confirming at which point of a plurality of points a Raman spectrum is acquired when the Raman spectrum at the plurality of points in a depth direction is acquired.SOLUTION: A depth measurement processing part 111 performs depth measurement by acquiring Raman spectra at a plurality of points in a depth direction while changing a focal position of a laser beam along the depth direction which is the irradiation direction of the laser beam to a sample. A display processing part 103 displays Raman spectra at a plurality of points obtained by the depth measurement. The display processing part 103 is capable of displaying a surface image of the sample on a stage and a depth image representing a plurality of points in the depth direction and displays the Raman spectrum corresponding to at least one point when at least one point of the plurality of points in the depth image is selected.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a Raman microscope that obtains a Raman spectrum by condensing and irradiating a laser beam on a sample on a stage and receiving Raman scattered light from the sample with a detector.

Background Art

[0002] In a Raman microscope, which is an example of a Raman spectroscopic apparatus, a laser beam is condensed and irradiated on a sample on a stage, and Raman scattered light from the sample is received by a detector (see, for example, Patent Document 1 below).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the Raman microscope as described above, by changing the focal position of the laser beam along the depth direction, which is the irradiation direction of the laser beam on the sample, it is possible to obtain Raman spectra at a plurality of points in the depth direction. In this case, when the user checks the plurality of obtained Raman spectra, it is not possible to easily confirm at which point among the plurality of points the Raman spectrum was obtained.

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide a Raman microscope that can easily confirm at which point among a plurality of points a Raman spectrum was obtained when Raman spectra at a plurality of points in the depth direction are obtained.

Means for Solving the Problems

[0006] A first aspect of the present invention is a Raman microscope that focuses and irradiates a sample on a stage with laser light and obtains a Raman spectrum by receiving Raman scattered light from the sample with a detector, comprising a depth measurement processing unit and a display processing unit. The depth measurement processing unit performs depth measurement by changing the focal position of the laser light along the depth direction, which is the direction in which the laser light is irradiated onto the sample, and obtaining Raman spectra at multiple points in the depth direction. The display processing unit displays the Raman spectra at the multiple points obtained by the depth measurement. The display processing unit is capable of displaying a surface image of the sample on the stage and a depth image representing the multiple points in the depth direction, and when at least one of the multiple points in the depth image is selected, it displays the Raman spectrum corresponding to that at least one point. [Effects of the Invention]

[0007] According to the present invention, when Raman spectra are obtained at multiple points in the depth direction, it is possible to easily determine which of the multiple points the Raman spectrum was obtained from. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram showing an example of a Raman microscope configuration. [Figure 2] This is a schematic diagram showing an example of a Raman microscope configuration. [Figure 3] This is a block diagram showing an example of the electrical configuration of a Raman microscope. [Figure 4] This diagram shows an example of the operation screen displayed on the display unit. [Modes for carrying out the invention]

[0009] 1. Overall configuration of a Raman microscope Figures 1 and 2 are schematic diagrams showing an example configuration of the Raman microscope 1. In this embodiment, the Raman microscope 1 can perform not only Raman spectroscopy but also infrared spectroscopy. Figure 1 shows the state when performing Raman spectroscopy, and Figure 2 shows the state when performing infrared spectroscopy.

[0010] The Raman microscope 1 is equipped with a plate 2, a stage 3, a drive unit 4, an objective optical element 5, an objective optical element 6, a Raman light detection system 7, an infrared light detection system 8, and a switching mechanism 9. The sample is fixed to the plate 2 and placed on the stage 3. The stage 3 can be displaced horizontally or vertically by the drive unit 4. The drive unit 4 includes, for example, a motor and gears.

[0011] The objective optical element 5 is used in Raman spectroscopy and is configured, for example, by combining a convex lens and a concave lens. When performing Raman spectroscopy, as shown in Figure 1, the objective optical element 5 faces the sample on the plate 2. That is, the objective optical element 5 is located directly above the sample on the plate 2.

[0012] The objective optical element 6 is used for infrared spectroscopy and is, for example, a Cassegrain mirror combining a concave mirror and a convex mirror. When performing infrared spectroscopy, as shown in Figure 2, the objective optical element 6 faces the sample on plate 2. That is, the objective optical element 6 is positioned directly above the sample on plate 2.

[0013] The Raman light detection system 7 is used when performing Raman spectroscopic analysis and includes a light source A, an optical imaging element 10, and a Raman spectrometer 71. The light emitted from the light source A is, for example, laser light having a wavelength in the visible or near-infrared region, and its wavelength is approximately a few micrometers to several tens of micrometers. As shown in Figure 1, when performing Raman spectroscopic analysis, the light emitted from the light source A is guided to the objective optical element 5 by various optical elements (not shown).

[0014] Light incident on the objective optical element 5 is focused onto the sample fixed to the plate 2. That is, light from the light source A is focused by passing through the objective optical element 5 and irradiates the sample or the focal point within the sample. Raman scattered light is generated from the sample irradiated with light from the light source A, and this light is guided to the Raman light detection system 7 by various optical elements (not shown). A portion of the light guided from the objective optical element 5 to the Raman light detection system 7 is incident on the optical imaging element 10, and the remaining light is incident on the Raman spectrometer 71.

[0015] The optical image sensor 10 captures a visible image of the sample surface where Raman scattered light is generated. The optical image sensor 10 includes, for example, a CCD (Charge Coupled Device) image sensor or a CMOS (Complementary Metal Oxide Semiconductor) image sensor, and is configured to capture still images or videos of the sample. The optical image sensor 10 can capture all or at least one of the following types of images of the sample: bright-field images, dark-field images, phase-contrast images, fluorescence images, and polarized light microscope images.

[0016] The Raman spectrometer 71 detects the intensity at each wavelength by spectrally analyzing the Raman scattered light from the sample. Based on the detection signal from this Raman spectrometer 71, a Raman spectrum can be obtained. In a Raman spectrum, the vertical axis represents intensity and the horizontal axis represents wavelength. Thus, in the Raman microscope 1, a Raman spectrum can be obtained by receiving the Raman scattered light from the sample with the detector (Raman spectrometer 71).

[0017] The infrared light detection system 8 is used when performing infrared spectroscopic analysis and includes a light source B, an optical imaging element 11, and an infrared spectrometer 81. The light emitted from the light source B is, for example, infrared light emitted from a ceramic heater, with wavelengths ranging from approximately 405 nm to 1064 nm, and in many cases, a combination of wavelengths 532 nm and 785 nm is used. As shown in Figure 2, when performing infrared spectroscopic analysis, the light emitted from the light source B is guided to the objective optical element 6 by various optical elements (not shown).

[0018] The light incident on the objective optical element 6 is focused on the sample fixed to the plate 2. That is, the light from the light source B is condensed by passing through the objective optical element 6 and irradiated to the focal position on or in the sample. The reflected light from the sample irradiated with the light from the light source B is guided to the infrared light detection system 8 by various optical elements (not shown). A part of the light guided from the objective optical element 6 to the infrared light detection system 8 is incident on the optical imaging element 11, and the remaining light is incident on the infrared spectrometer 81.

[0019] The optical imaging element 11 captures a visible image of the sample surface where infrared light is reflected. The optical imaging element 11 may have the same configuration as the optical imaging element 10. Similar to the optical imaging element 10, the optical imaging element 11 can capture a still image or a moving image of the sample, and can capture all or at least one of a bright-field image, a dark-field image, a phase-contrast image, a fluorescence image, and a polarized light microscope image of the sample.

[0020] The infrared spectrometer 81 is, for example, a Fourier transform infrared spectrometer. The spectroscope provided in the infrared spectrometer 81 may be a Michelson interferometric spectroscope. The infrared spectrometer 81 detects the intensity for each wavelength by spectroscopically analyzing the reflected light of the infrared light from the sample. Based on the detection signal from the infrared spectrometer 81, an infrared spectrum can be obtained. The infrared spectrum is represented with the intensity on the vertical axis and the wavelength on the horizontal axis. Thus, in the Raman microscope 1, an infrared spectrum can be obtained by receiving the reflected light of the infrared light from the sample with a detector (infrared spectrometer 81).

[0021] The switching mechanism 9 switches between Raman spectroscopy analysis and infrared spectroscopy analysis. Specifically, the switching mechanism 9 drives the stage 3 by the drive unit 4 to adjust the positional relationship between the objective optical element 5 and the plate 2, and the positional relationship between the objective optical element 6 and the plate 2. When switched to Raman spectroscopy analysis, the positional relationship between the objective optical element 5 and the plate 2 is adjusted, so that the focal position of the light collected by the objective optical element 5 is adjusted to a predetermined measurement position of the sample. On the other hand, when switched to infrared spectroscopy analysis, the positional relationship between the objective optical element 6 and the plate 2 is adjusted, so that the focal position of the light collected by the objective optical element 6 is adjusted to a predetermined measurement position of the sample.

[0022] 2. Electrical Configuration of Raman Microscope FIG. 3 is a block diagram showing an example of the electrical configuration of the Raman microscope 1. In addition to the above-described respective parts, the Raman microscope 1 includes a control unit 100, a storage unit 200, a display unit 300, and an operation unit 400.

[0023] The control unit 100 has a configuration including, for example, a CPU (Central Processing Unit). The control unit 100 functions as a Raman analysis processing unit 101, an infrared analysis processing unit 102, a display processing unit 103, etc. when the CPU executes a program.

[0024] The Raman analysis processing unit 101 executes processing for performing Raman spectroscopy analysis on a sample on the stage 3 in a state switched to Raman spectroscopy analysis by the switching mechanism 9. That is, laser light is collected and irradiated from the light source A onto the sample, and a Raman spectrum is acquired based on a detection signal from the Raman spectrometer 71. In addition, the Raman analysis processing unit 101 can acquire a surface image of the sample during Raman spectroscopy analysis based on a visible image captured by the optical imaging element 10. During Raman spectroscopy analysis, the analysis may be performed while moving the stage 3 by controlling the drive unit 4.

[0025] The infrared analysis processing unit 102, after being switched to infrared spectroscopic analysis by the switching mechanism 9, performs processing for infrared spectroscopic analysis on the sample on stage 3. That is, infrared light is focused and irradiated onto the sample from the light source B, and an infrared spectrum is acquired based on the detection signal from the infrared spectrometer 81. The infrared analysis processing unit 102 can also acquire a surface image of the sample during infrared spectroscopic analysis based on the visible image captured by the optical image sensor 11. During infrared spectroscopic analysis, the analysis may be performed while moving stage 3 by controlling the drive unit 4.

[0026] The data obtained during Raman spectroscopy analysis by the Raman analysis processing unit 101, and the data obtained during infrared spectroscopy analysis by the infrared analysis processing unit 102, are stored in the storage unit 200. The storage unit 200 includes, for example, non-volatile memory such as a hard disk. The storage unit 200 stores, for example, Raman spectra obtained by Raman spectroscopy analysis and infrared spectra obtained by infrared spectroscopy analysis.

[0027] The display processing unit 103 controls the display on the display unit 300. That is, under the control of the display processing unit 103, various screens such as operation screens are displayed on the display screen of the display unit 300. The display unit 300 includes, for example, a liquid crystal display, but is not limited to this configuration. Under the control of the display processing unit 103, the display screen of the display unit 300 can display a Raman spectrum or infrared spectrum stored in the storage unit 200.

[0028] The operation unit 400 is for the user to perform input operations and includes, but is not limited to, a keyboard or mouse. When an operation screen is displayed on the display unit 300, the user can perform input operations on the operation screen by operating the operation unit 400. When an input operation is performed using the operation unit 400, the entered information (such as numerical values) is reflected and displayed on the operation screen of the display unit 300.

[0029] In this embodiment, the Raman analysis processing unit 101 includes a depth measurement processing unit 111. The depth measurement processing unit 111 controls the drive unit 4 during Raman spectroscopy to move the stage 3 vertically and acquire Raman spectra at multiple points, thereby performing depth measurement. That is, during depth measurement, the distance between the sample and the objective optical element 5 changes as the stage 3 moves vertically.

[0030] Since the focal position of the laser beam directed from the objective optical element 5 towards the sample is constant, during depth measurement, the focal position of the laser beam relative to the sample changes as the stage 3 moves. In other words, the focal position of the laser beam irradiated onto the sample during depth measurement extends not only above the sample but also into the sample itself.

[0031] Specifically, in depth measurement, the focal position of the laser beam is changed along the depth direction, which is the direction of laser beam irradiation (optical axis direction) onto the sample, and Raman spectra are acquired at predetermined intervals based on the detection signals from the Raman spectrometer 71. As a result, Raman spectra based on the detection signals from the Raman spectrometer 71 are acquired at multiple points separated by the predetermined intervals in the depth direction. The predetermined intervals can be set in advance by the user.

[0032] The display processing unit 103 can display Raman spectra at multiple points obtained by depth measurement on the display unit 300. The display processing unit 103 may also display various other screens on the display unit 300, such as an input screen for inputting parameters for depth measurement. These parameters include, in addition to the predetermined intervals, the depth range for depth measurement, or the diameter of the laser beam (spot diameter) on the surface image of the sample. The depth measurement processing unit 111 performs depth measurement based on the parameters entered on the input screen.

[0033] 3. Specific examples of user interface screens Figure 4 shows an example of an operation screen 500 displayed on the display unit 300. This operation screen 500 includes a surface image display area 501, a depth image display area 502, and a spectrum display area 503. However, the surface image display area 501, the depth image display area 502, and the spectrum display area 503 are not limited to the display modes included in the operation screen 500, and at least one of them may be displayed on a screen different from the operation screen 500.

[0034] The surface image display area 501 displays a surface image of the sample on stage 3. That is, a visible image captured by the optical image sensor 10 is displayed in the surface image display area 501. The surface image of the sample displayed in the surface image display area 501 may be a real-time image captured by the optical image sensor 10, or a still image captured at a predetermined timing. If stage 3 is moved horizontally (intersecting the depth direction), the area of ​​the surface image of the sample displayed in the surface image display area 501 may change.

[0035] The user can select a measurement location on the surface image of the sample. The measurement location is any position selected within the horizontal plane, and depth measurement is performed along the depth direction at the selected measurement location.

[0036] One measurement position may be selected, or multiple positions may be selected. In the example in Figure 4, four measurement positions 511 are selected and depth measurement is performed. Furthermore, the multiple measurement positions 511 are selected so as to be aligned in a straight line. The measurement positions 511 are selected by operation on the operation unit 400, but the method of selection is arbitrary. For example, if the operation unit 400 includes a pointing device such as a mouse, multiple measurement positions 511 can be easily selected by drag operation, etc. The distance between the multiple measurement positions 511 in the horizontal direction may or may not be constant.

[0037] Furthermore, the light source A in the Raman light detection system 7 may be capable of emitting laser light at multiple wavelengths. In this case, the measurement position selected on the surface image of the sample displayed in the surface image display area 501 may be selectable for each wavelength.

[0038] The depth image display area 502 displays a depth image in which multiple points in the depth direction are associated with each measurement position 511. The depth image is a mapping image that visually displays the relative positions of multiple points 521 in the depth direction associated with each measurement position 511 in a two-axis display: the direction in which each measurement position 511 is aligned in a straight line in the horizontal plane (line axis) and the depth direction when depth measurement is performed. The user can select any point 521 on this depth image. In this example, the depth image is displayed so that the line axis and the depth direction are orthogonal, but a display mode in which they are not orthogonal is also possible. Furthermore, the depth image is not limited to a two-axis display, and multiple points 521 in the depth direction can be displayed in an easy-to-understand manner in any other manner.

[0039] In this example, a depth image representing multiple points 521 in the depth direction is displayed in the depth image display area 502, corresponding to each of the four measurement positions 511 selected on the surface image of the sample. The number of points 521 in the depth direction varies depending on the value set as a parameter when performing the depth measurement. That is, the number of points 521 displayed in the depth image display area 502 corresponding to each measurement position 511 differs depending on the depth direction range when performing the depth measurement and the spacing between the multiple points in the depth direction.

[0040] The distance between each point 521 arranged along the line axis (horizontal axis) in the depth image display area 502 may or may not change depending on the actual distance between the multiple measurement positions 511 selected on the surface image of the sample. Similarly, the distance between each point 521 arranged along the depth axis (vertical axis) in the depth image display area 502 may or may not change depending on the actual spacing between the multiple points during depth measurement. Note that if only one measurement position 511 is selected on the surface image of the sample, one point 521 will be displayed on the line axis (horizontal axis), and multiple points 521 will be displayed in a single row on the depth axis (vertical axis).

[0041] The user can select at least one point 521 from a plurality of points displayed in the depth image display area 502 to display the Raman spectrum corresponding to the desired point 521 in the spectrum display area 503. In other words, when at least one point 521 from a plurality of points in the depth image is selected, the display processing unit 103 displays the Raman spectrum corresponding to that point in the spectrum display area 503.

[0042] If only one point 521 is selected, the Raman spectrum acquired at that selected point 521 during depth measurement is displayed in the spectrum display area 503. On the other hand, if multiple points 521 are selected, the Raman spectra acquired at each of those points 521 during depth measurement may be displayed side by side, some or all of them may be superimposed, or the user may arbitrarily select which ones to display.

[0043] In the embodiments described above, only the case of Raman spectroscopy has been explained, but the infrared spectrum obtained by infrared spectroscopy may also be displayed on the operation screen 500. In this case, for example, in the surface image display area 501, the measurement position of the infrared spectroscopy may be displayed in a different display manner so as to be distinguishable from the measurement position 511 of the Raman spectroscopy.

[0044] 4. Appearance Those skilled in the art will understand that the above-described exemplary embodiments are specific examples of the following embodiments.

[0045] (Article 1) A Raman microscope relating to one aspect is: A Raman microscope that focuses and irradiates a sample on a stage with laser light, and obtains a Raman spectrum by receiving the Raman scattered light from the sample with a detector, A depth measurement processing unit performs depth measurement by changing the focal position of the laser beam along the depth direction, which is the direction in which the laser beam is irradiated onto the sample, and acquiring Raman spectra at multiple points in the depth direction. The system includes a display processing unit that displays the Raman spectra at the multiple points obtained by the depth measurement, The display processing unit is capable of displaying a surface image of the sample on the stage and a depth image representing multiple points in the depth direction. If at least one of the multiple points in the depth image is selected, the unit may display the Raman spectrum corresponding to that at least one point.

[0046] According to the Raman microscope described in paragraph 1, when Raman spectra are acquired at multiple points in the depth direction, the depth image can clearly represent these multiple points in the depth direction. Therefore, by selecting at least one point from the multiple points in the depth image and displaying the Raman spectrum corresponding to that point, it is easy to confirm which of the multiple points the Raman spectrum was acquired from.

[0047] (Section 2) In the Raman microscope described in Section 1, The depth measurement processing unit is capable of acquiring Raman spectra at multiple points in the depth direction while changing the focal position of the laser beam along the depth direction at multiple measurement positions on the surface image. The depth image may represent multiple points in the depth direction, each corresponding to one of the multiple measurement positions.

[0048] According to the Raman microscope described in Section 2, even if Raman spectra are obtained at multiple points in the depth direction at multiple measurement positions on the surface image, the depth image can clearly represent these multiple points in the depth direction.

[0049] (Section 3) In the Raman microscope described in Section 2, The plurality of measurement positions are selected so as to be aligned in a straight line on the surface image. The depth image may display multiple points in the depth direction, each corresponding to one of the multiple measurement positions, using a two-axis display: the direction in which the multiple measurement positions are aligned and the depth direction.

[0050] According to the Raman microscope described in Section 3, even when Raman spectra are acquired at multiple points in the depth direction at multiple measurement positions on a surface image, the multiple points in the depth direction can be clearly represented by a depth image, which is displayed in a two-axis view of the direction in which the multiple measurement positions are aligned and the depth direction. [Explanation of Symbols]

[0051] 1. Raman Microscope 3 stages 71 Raman Spectrometer 100 Control Unit 101 Raman Analysis Processing Unit 102 Infrared Analysis Processing Unit 103 Display Processing Unit 111 Depth Measurement Processing Unit 500 operation screen 501 Surface image display area 502 Depth Image Display Area 503 Spectral display area 511 Measurement position 521 points

Claims

[Claim 1] A Raman microscope that focuses and irradiates a sample on a stage with laser light, and obtains a Raman spectrum by receiving the Raman scattered light from the sample with a detector, A depth measurement processing unit performs depth measurement by changing the focal position of the laser beam along the depth direction, which is the direction in which the laser beam is irradiated onto the sample, and acquiring Raman spectra at multiple points in the depth direction. The system includes a display processing unit that displays the Raman spectra at the multiple points obtained by the depth measurement, The display processing unit is capable of displaying a surface image of the sample on the stage and a depth image representing multiple points in the depth direction, and when at least one of the multiple points in the depth image is selected, it displays the Raman spectrum corresponding to that at least one point. The depth measurement processing unit is capable of acquiring Raman spectra at multiple points in the depth direction while changing the focal position of the laser beam along the depth direction at multiple measurement positions on the surface image. The plurality of measurement positions are selected so as to be aligned in a straight line on the surface image. The depth image is a Raman microscope in which multiple points in the depth direction are represented in a two-axis display, corresponding to each of the multiple measurement positions, in the direction in which the multiple measurement positions are aligned and in the depth direction.

Images