Laser Raman Microscope

Abstract

By using multiple laser oscillators, strong laser light can be directed to the AF control unit during measurement or sample observation, enabling high-precision Raman measurements with high-precision autofocus and focus on the sample without directing strong laser light into the observation camera. [Solution] The monochromatic excitation light beam emitted by the laser oscillator 2 is reflected by the alignment mirror 3, passes through the first beam splitter 4, is reflected by the rejection filter 5, and irradiates the sample S through the objective lens 6. It then travels back to the first beam splitter 4, is reflected, and enters the AF control unit 8, where the misalignment between the focal point of the objective lens 6 and the sample S is corrected. Furthermore, the Raman scattered light scattered from the sample S is guided to the spectrometer 9 for spectral analysis, and this light is detected by the detector 10. Additionally, the illumination light from the illuminator 12 is irradiated onto the sample S via a movable reflector 11 positioned in the optical path of the scattered light that has passed through the rejection filter 5, and the reflected light reflecting the surface shape of the sample S is captured by the observation camera 15.

Description

【Technical Field】 【0001】 The present invention relates to a laser Raman microscope. 【Background Art】 【0002】 A laser Raman microscope is composed of a confocal optical system and selectively measures the spectrum at the focal position on a sample. When the measurement position deviates from the focus, the spectrum intensity weakens or the spectrum at the target position cannot be measured. In mapping measurement, the measurement is performed while moving the stage in the XY directions. When the sample has unevenness or inclination and the Z position at which focusing occurs varies depending on the location, in the mapping measurement at only one Z position, a good spectrum cannot be obtained over the entire sample surface. Therefore, a method of executing autofocus (hereinafter also referred to as "AF") that automatically adjusts the focal position every time the stage moves in the XY directions is adopted. 【0003】 As methods of AF, a method using the contrast of an image and a method using the excitation laser light used for the measurement of Raman scattered light (laser AF) are adopted. When using the contrast of an image, the illumination light irradiated on the sample becomes an obstacle to the measurement of Raman scattered light, so AF cannot be executed during the measurement. Also, since the difference in contrast due to the focal position is small for a mirror sample, AF using the contrast of an image cannot be executed. On the other hand, laser AF can be executed simultaneously with the measurement of Raman scattered light and is applicable to mirror samples. 【Prior Art Documents】 【Patent Documents】 【0004】 【Patent Document 1】 Japanese Patent Application Laid-Open No. 2004-251984 【Patent Document 2】 US 10,067,058 B1 【Patent Document 3】 Japanese Patent No. 5792792 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0005】 In AF methods using excitation laser light, a mask that blocks the laser light is generally placed in front of the sample. However, this presents a problem: the laser intensity irradiated onto the sample is weakened, reducing the sensitivity of the Raman scattered light. 【0006】 A laser Raman microscope is composed of a confocal optical system that selectively measures the spectrum at the focal point on the sample. However, if the measurement position is off-center, the spectral intensity weakens, or the spectrum at the target position cannot be measured at all. 【0007】 In mapping measurements, measurements are taken while moving the stage in the XY direction. If the sample has irregularities or inclination, and the focal Z position differs depending on the location, mapping measurements at only one Z position will not yield a good spectrum across the entire sample. Therefore, an autofocus technique is used, which automatically adjusts the focal position each time the stage is moved in the XY direction. 【0008】 The laser light irradiated onto the sample is focused again by the objective lens as Rayleigh scattered light. If the Rayleigh scattered light were to directly enter the observation camera, the camera would be damaged by the strong light. As a countermeasure, a filter is used to reduce the intensity of the light entering the observation camera, but this presents the challenge of increasing the total number of filters in the entire system when a filter is installed for the camera. 【0009】 In Raman measurements, it is crucial to use an appropriate excitation wavelength for the sample. Changing the type of laser and thus the excitation wavelength can cause the optical axis incident on the objective lens to shift, altering the image formation position on the detector, or chromatic aberration to change the focal point of the imaging lens. Until now, there has been no laser autofocus mechanism that can accommodate changes in laser wavelength. 【0010】 The present invention has been made in view of the above problems, and its objective is to provide a laser Raman microscope that can measure a sample with a focused position by using multiple laser oscillators and applying autofocus (laser AF), and can input a monochromatic excitation light beam that is not weakened by the AF control unit into the sample, allowing strong Raman scattered light to be input into the spectrometer, thereby enabling measurement with higher precision than before, and can brightly irradiate the sample with illumination light in a switchable manner between measurement of Raman scattered light, and can also apply the AF control unit during observation, allowing observation with a focused position without strong light entering the observation camera and causing damage. [Means for solving the problem] 【0011】 The laser Raman microscope according to the first aspect of this application has the following configuration in order to solve the above problem. That is, The system has a laser oscillator, and the monochromatic excitation beam emitted by the laser oscillator is positioned to intersect the optical path at a required angle and is reflected by an alignment mirror that fine-tunes the optical path of the monochromatic excitation beam. A first beam splitter is positioned at a required angle to intersect the optical path of the monochromatic excitation light beam after reflection by the alignment mirror, and a rejection filter with a required high reflectivity corresponding to the wavelength of the monochromatic excitation light beam is positioned at a predetermined location so as to intersect the subsequent optical path at a required angle. As a result, the monochromatic excitation light beam reflected by the alignment mirror passes through the first beam splitter and is further reflected by the rejection filter in the direction that irradiates the sample. The monochromatic excitation light beam, after being reflected by the rejection filter, is focused at the end of an objective lens placed in the optical path, and is focused and irradiated onto the sample placed on the XY stage of a composite stage apparatus, which is a combination of an XY stage and a Z stage. The monochromatic excitation light beam reflected or scattered by the sample is reflected from the rejection filter, travels back to the first beam splitter, and is reflected into an AF control unit positioned in the reflection direction. The AF control unit performs the necessary calculations to determine the positional misalignment between the focal point of the objective lens and the sample, and raises or lowers the Z-stage to correct the misalignment. Furthermore, when a monochromatic excitation light beam is incident on the sample, the Rayleigh scattered light and Raman scattered light from the sample that passes through the rejection filter are guided to a spectrometer to spectrally analyze at least the Raman scattered light, and the spectrally analyzed light is detected by a detector. A movable reflector is positioned in the optical path after the Rayleigh scattered light and the Raman scattered light have passed through the rejection filter. This reflector is switched between a state where it intersects the sample surface at a required angle during surface observation and a state where it is removed from the optical path when not being observed. An illumination lamp that emits illumination light for observing the surface of the sample, the illumination lamp is equipped with a second beam splitter and a movable reflector that reflect the illumination light, which is then transmitted through a rejection filter and an objective lens to illuminate the sample, and an observation camera that captures the reflected light, which reflects the surface shape and color of the sample and is reflected by the illumination light, as it travels back to the second beam splitter and is transmitted through the reflected light. The laser oscillators are arranged in multiple units to emit monochromatic excitation light beams of different wavelengths, and the rejection filters are arranged in multiple units having the required high reflectivity corresponding to each wavelength of the monochromatic excitation light beams of the multiple laser oscillators. One of the multiple laser oscillators is configured to emit a monochromatic excitation light beam, and one of the multiple rejection filters is selected in a one-to-one correspondence with the laser oscillator, and the selected rejection filter is moved alternately to the predetermined position. The system is configured so that the overall requirements of the device are controlled by a PC. 【0012】 In a second aspect of the present application, in the first aspect described above, a plurality of laser oscillators may be fixedly arranged, and a monochromatic excitation light beam emitted from one of the selected laser oscillators may be incident on the alignment mirror via a plurality of mirrors in the same optical path. 【0013】 In a third aspect of the present application, in the first embodiment described above, a plurality of laser oscillators may be arranged on a movable table, and by scanning the movable table, one of the laser oscillators may be selected and moved to the oscillation position, so that the monochromatic excitation light beam emitted from the selected laser oscillator is incident on the alignment mirror in the same optical path. 【0014】 In a fourth aspect of the present application, the AF control unit may be configured to calculate the positional misalignment between the focal point of the objective lens and the sample using one of the following methods: pupil division method, knife edge method, optical path difference pinhole method, Foucault method, critical angle method, phase difference method, and astigmatism method. 【0015】 In a fifth aspect of the present application, in the fourth aspect described above, the AF control unit may include a blade, a lens, a detector, a calculation unit, and a motor driver, wherein the blade partially blocks the light beam, and the calculation unit performs the necessary calculations based on the detection position of the monochromatic excitation light beam on the detector to calculate the positional misalignment between the focal point of the objective lens and the sample, and the motor driver drives the Z-stage to raise or lower in order to correct the positional misalignment. 【0016】 In a sixth aspect of this application, in the first embodiment described above, the spectrometer may be configured such that the Raman scattered light is spectrally analyzed by a diffraction grating, a filter, or a Fourier transform. 【0017】 As a seventh aspect of the present application, in the first aspect, a configuration may be provided that includes means for controlling the distance between another sample and the objective lens that can complement the control range of the AF control unit separately from the AF control unit. 【Advantages of the Invention】 【0018】 According to each aspect of the present invention, measurement with the focal position adjusted can be performed by using a plurality of laser oscillators and applying autofocus (laser AF), and a monochromatic excitation light beam that cannot be attenuated by the AF control unit can be incident on the sample, and strong Raman scattered light or the like can be incident on the spectroscope, enabling measurement with higher accuracy than before. Also, the illumination light can be brightly irradiated on the sample in a switching manner with the measurement of Raman scattered light or the like, and the AF control unit can be applied in observation as well, allowing for observation with the focal position adjusted without strong light damaging the observation camera. A laser Raman microscope can be provided. 【Brief Description of the Drawings】 【0019】 [Figure 1] It is a schematic configuration diagram of a laser Raman microscope according to an embodiment of the present invention. 【Embodiments for Carrying Out the Invention】 【0020】 The laser Raman microscope of the present invention will be described below with reference to the drawings. 【0021】 The laser Raman microscope 1 according to the embodiment of the present invention shown in FIG. 1 has the following configuration. The laser Raman microscope 1 is configured to perform overall required control of the apparatus by the PC 16 (in FIG. 1, for convenience of explanation, the PC 16 is depicted as being connected to the arithmetic unit 8E). 【0022】 As shown in Figure 1, the laser Raman microscope 1 of this embodiment is configured to select one of several laser oscillators, for example, first, second, and third laser oscillators 2A, 2B, and 2C, to oscillate a monochromatic excitation light beam of the required wavelength. The wavelength of the monochromatic excitation light beam can be selected from, for example, 457 nm (blue laser), 532 nm (green laser), 785 nm (near-infrared laser), and 1064 nm (near-infrared laser) depending on the object of analysis and purpose, and in particular, the optimal wavelength is selected based on the specific application and characteristics of the sample. The PC16 selects one laser oscillator and performs the control necessary for the oscillation of the monochromatic excitation light beam. 【0023】 One of the first, second, and third laser oscillators 2A, 2B, and 2C is selected, and one of the first, second, and third rejection filters 5A, 5B, and 5C, which are set to have a high reflectivity (e.g., 90% reflectivity) corresponding to the wavelength of the monochromatic excitation light beam, is selected and interchangeably placed in a predetermined position to reflect the monochromatic excitation light beam and irradiate the sample S. Notch filters or dichroic mirrors are applicable as rejection filters. 【0024】 The first, second, and third laser oscillators 2A, 2B, and 2C correspond one-to-one with the first, second, and third rejection filters 5A, 5B, and 5C, and the selected rejection filter is moved alternately to a predetermined position. In Figure 1, the configuration for moving multiple rejection filters alternately is shown with the first, second, and third rejection filters 5A, 5B, and 5C arranged on a movable table that slides 45 degrees to the left, but they may also be arranged on a movable table that slides plane-to-plane (perpendicular to the figure), or on a movable table that slides 45 degrees to the right. Furthermore, the movable table may be a turntable. 【0025】 The monochromatic excitation light beam reflected by the rejection filter is focused by the objective lens 6 and directed onto the sample S at the focal point. The first, second, and third rejection filters 5A, 5B, and 5C are arranged on a movable table, and the movable table operates based on the instructions and control of the PC 16, selecting the rejection filter that is in the predetermined position. 【0026】 The monochromatic excitation beam emitted by the selected laser oscillator is reflected by one or two of the mirrors 17A, 17B, and 17C, then reflected by the first and second alignment mirrors 3A and 3B, and further transmitted through the first beam splitter 4 before being incident on a (selected) rejection filter that is interchangeably positioned at a predetermined location. The first and second alignment mirrors 3A and 3B have the function of preventing the spectral intensity from weakening or the spectrum at the target position from being measured if the monochromatic excitation beam is deviated from the optical axis and thus deviates from the focal point relative to the sample S. 【0027】 The monochromatic excitation light beam reflected or scattered by the sample S passes through the objective lens 6, is reflected by the rejection filter, is reflected back to the first beam splitter 4, and enters the AF control unit 8. Based on the incoming monochromatic excitation light beam, the AF control unit 8 performs the necessary calculations to calculate the positional misalignment between the focal point of the objective lens 6 and the sample S, and drives the motor 7B1 of the Z stage 7B to raise or lower the Z stage 7B in order to correct the misalignment. As a result, the focal position is adjusted so that the sample S matches the focal length of the objective lens 6. 【0028】 When a monochromatic excitation light beam is irradiated onto the sample S, Rayleigh scattered light and Raman scattered light are generated from the sample S. This Rayleigh scattered light and Raman scattered light, along with the reflected light, fluorescence, and photoluminescence of the monochromatic excitation light beam, pass through the rejection filter 5 and enter the spectrometer 9. The spectrometer 9 spectrally analyzes the Raman scattered light, blocks out the other light, and the detector detects the spectrally analyzed Raman scattered light. The spectrometer 9 may also be configured to perform spectral analysis of Rayleigh scattered light, fluorescence, and photoluminescence in addition to Raman scattered light, and the detector 10 will also detect the spectrally analyzed light of Rayleigh scattered light, fluorescence, and photoluminescence. 【0029】 A movable reflector 11 is positioned in the optical path between the rejection filter 5 and the spectrometer 9. Illumination light from the illuminator 12 is reflected by the second beam splitter 14 and the movable reflector 11, passes through the rejection filter 5 and objective lens 6, and enters the sample S. The reflected light from the sample S reflects the shape and color of the sample S's surface, travels back to the second beam splitter 14, and is captured by the observation camera 15. 【0030】 Further details are provided below. A monochromatic excitation light beam emitted from one of the first, second, and third laser oscillators 2A, 2B, and 2C is incident on the first alignment mirror 3A via the first, second, and third mirrors 17A, 17B, and 17C, following the same optical path. 【0031】 When the first laser oscillator 2A is selected, the oscillating monochromatic excitation light beam is not blocked by the first mirror 17A, which is a movable mirror set parallel to the optical path, but is reflected sequentially by the first alignment mirror 3A and the second alignment mirror 3B. 【0032】 When the second laser oscillator 2B is selected, the oscillating monochromatic excitation light beam is reflected by the second mirror 17B, which is a fixed mirror intersecting the optical path at a required angle (45°), then reflected again by the first mirror 17A, which is also intersecting the optical path at a required angle (45°) after changing direction by another 45°, and then reflected sequentially by the first and second alignment mirrors 3A and 3B. 【0033】 When the third laser oscillator 2C is selected, the oscillating monochromatic excitation light beam is reflected by the third mirror 17C, which is a fixed mirror intersecting the optical path at a required angle (45°), then reflected again by the first mirror 17A, which is rotated 90°, and then reflected sequentially by the first and second alignment mirrors 3A and 3B. 【0034】 Furthermore, the first and second alignment mirrors 3A and 3B can subtly change the reflection direction by pivoting based on the instructions and control of the PC16, and have the function of fine-tuning the optical axes, which would be different depending on the selection and switching of the first, second, and third laser oscillators 2A, 2B, and 2C, to become coaxial. 【0035】 Furthermore, the laser Raman microscope 1 may be configured such that when one of the first, second, and third laser oscillators 2A, 2B, and 2C is selected, the light beam enters the first alignment mirror 3A via the same optical path without passing through the first, second, and third mirrors 17A, 17B, and 17C. Specifically, the first, second, and third laser oscillators 2A, 2B, and 2C may be arranged on a movable table, and based on the instructions and control of the PC 16, the movable table is moved to a predetermined position, indicating that one laser oscillator has been selected, and the oscillating monochromatic excitation light beam is directly incident on the first alignment mirror 3A. 【0036】 The monochromatic excitation light beam emitted by the first laser oscillator 2A, the second laser oscillator 2B, or the third laser oscillator 2C is reflected sequentially by the first and second alignment mirrors 3A and 3B, then passes through the first beam splitter 4, which is positioned at a predetermined angle (45°) along the optical path, and is further reflected with high reflectivity (e.g., 90% reflectivity) by the first rejection filter 5A, the second rejection filter 5B, or the third rejection filter 5C, which are positioned at a predetermined angle (45°) along the optical path and alternately correspond to the laser oscillators 2A, 2B, or 2C, so as to irradiate the sample S placed on the composite stage device 7. 【0037】 The combined stage device 7 consists of an XY stage 7A and a Z stage 7B that raises and lowers the XY stage 7A. The XY stage 7A operates to move the observation point of the sample S based on the instructions and control of the PC 16. The Z stage 7B operates to move vertically based on the instructions and control of the AF control unit 8 to focus the objective lens 6 on the sample S. 【0038】 Light scattered or reflected by sample S travels backward to the first beam splitter 4, is reflected, and enters the AF control unit 8, which is positioned in the direction of reflection. 【0039】 The AF control unit 8 reduces the light intensity of the monochromatic excitation light beam, then performs the necessary calculations to calculate the positional misalignment between the focal point of the objective lens 6 and the sample S, and raises or lowers the Z stage 7B to correct the misalignment. 【0040】 The AF control unit 8 includes, for example, a dimming unit 8A, a blade 8B, a lens 8C, a detector 8D, a calculation unit 8E, and a motor driver 8F. The dimming unit 8A reduces the amount of light, the blade 8B partially blocks the light beam, and the lens 8C focuses the light onto the detector 8D. The calculation unit 8E then performs the necessary calculations based on the detection position of the monochromatic excitation light beam on the detector 8D to calculate the misalignment between the focal point of the objective lens 6 and the sample S. The motor driver 8F then drives the Z-stage up or down to correct the misalignment. The detector can be a segmented PD (photodiode), a line sensor, a PSD sensor, or a two-dimensional sensor (CCD or CMOS). 【0041】 The calculation unit 8E of the AF control unit 8 is configured to calculate the positional misalignment between the focal point of the objective lens 6 and the sample S using one of the following methods: pupil division method, knife edge method, optical path difference pinhole method, Foucault method, critical angle method, phase difference method, and astigmatism method. 【0042】 In addition to the AF control unit 8, there may be another means for controlling the distance between the sample and the objective lens 6 that can complement the control range of the AF control unit. That is, laser AF control has a range of distances in which it can operate normally, and attempting to operate it beyond that range may result in malfunction, potentially causing the objective lens 6 and the sample S to collide. To compensate for this, it is desirable to have a distance control means separate from the laser AF. The means for controlling the distance may be a camera that photographs the sample from the side on the sample stage (lateral observation), or it may be an image from an observation camera, or it may be distance measurement using laser light, and the means are not particularly limited. 【0043】 Furthermore, as the monochromatic excitation light beam is incident on the sample S, some of the Rayleigh scattered light and Raman scattered light scattered from the sample S are transmitted through the first rejection filter 5A. This Rayleigh scattered light and Raman scattered light are then fed into the spectrometer 9. 【0044】 The spectrometer 9 is configured to spectrally analyze Raman scattered light and detect the spectrally analyzed light with the detector 10. The detector 10 may be, for example, a CCD detector or an InGaAs detector. 【0045】 The spectrometer 9 may include, for example, a reflective mirror, an aperture, a rejection filter, a lens, and a spectral section, and may be configured to spectrally analyze Raman scattered light. However, it may also be configured to spectrally analyze using a diffraction grating, a filter, or a Fourier transform. 【0046】 The movable reflector 11 is positioned in the optical path of Rayleigh scattered light and Raman scattered light between the first rejection filter 5A and the spectrometer 9. This movable reflector 11 is supported by a movable table that moves based on control commands output from the PC 16, and by moving the movable table, it can be switched between a state where it intersects at a required angle when observing the surface of the sample S and a state where it is removed from the optical path when not observing. 【0047】 The illumination lamp 12 emits illumination light for observing the surface of a sample S. The illumination lamp 12 includes a mirror 13 that intersects the illumination light at a 45° angle in the optical path, a second beam splitter 14 and a movable reflector 11, and the illumination light is transmitted through a rejection filter 5 and an objective lens 6 to illuminate the sample S. The illumination lamp 12 also includes an observation camera 15 that captures the reflected light, which reflects the shape and color of the surface of the sample S, as it travels back to the second beam splitter 14 and is transmitted through. 【0048】 When the laser Raman microscope 1 uses a camera image to adjust the focal position of the objective lens 6 to match the surface of the sample S, it processes the image captured by the camera. 【0049】 According to the laser Raman microscope of the present invention, by using multiple laser oscillators that emit monochromatic excitation light beams of different wavelengths, autofocus (laser AF) can be applied when measuring a sample, enabling measurements with a correct focal position. Furthermore, since the monochromatic excitation light beam enters the AF control unit after it has entered the sample, the laser light from the laser oscillator enters the sample with high efficiency, so the Raman scattered light can be entered into the spectrometer without attenuation, and the spectrum of the Raman scattered light can be measured with higher precision than before. In addition, by providing a movable reflector after the rejection filter, the Raman scattered light The system allows for both measurement and switching between illuminating the sample with and without illumination. During Raman spectroscopy, Raman scattered light from the sample is efficiently directed into the Raman spectrometer. While some Rayleigh and Raman scattered light from the sample enters the observation camera during observation, no light-reducing filter is used directly in front of the camera. This allows for bright and clear observation of the sample. Furthermore, even without a light-reducing filter, strong Rayleigh scattered light that could damage the camera is not detected. Laser autofocus can also be applied during observation, enabling bright observation with a sharp focus. If the spectrometer has the capability to perform spectroscopy of Rayleigh scattered light, fluorescence, and photoluminescence in addition to Raman spectroscopy, measurements can be performed with higher precision than before, similar to Raman spectroscopy. [Explanation of Symbols] 【0050】 1…Laser Raman microscope, 2A...First laser oscillator, 2B...Second laser oscillator, 2C... Third laser oscillator, 3A...First alignment mirror, 3B... Second alignment mirror, 4... The first beam splitter, 5A...First rejection filter, 5B... Second rejection filter, 5C... The third rejection filter, 6…Objective lens, 7…Composite stage device, 7A...XY Stage, 7B...Z Stage, 7B1...motor, 8...AF control unit, 8A... Dimmer, 8B...Blade, 8C...Lens, 8D... Detector, 8E...Arithmetic section, 8F...Motor driver, 9...Spectrometer, 10... Detector, 11...Movable reflector, 12... Lighting fixtures, 13... Miller, 14... The second beam splitter, 15… Observation camera, 16...PC, 17A...First mirror, 17B... The second Mirror, 17C... The third mirror, S... Sample.

Claims

[Claim 1] The system has a laser oscillator, and the monochromatic excitation beam emitted by the laser oscillator is positioned to intersect the optical path at a required angle and is reflected by an alignment mirror that fine-tunes the optical path of the monochromatic excitation beam. A first beam splitter is positioned at a required angle to intersect the optical path of the monochromatic excitation light beam after reflection by the alignment mirror, and a rejection filter with a required high reflectivity corresponding to the wavelength of the monochromatic excitation light beam is positioned at a predetermined location so as to intersect the subsequent optical path at a required angle. As a result, the monochromatic excitation light beam reflected by the alignment mirror passes through the first beam splitter and is further reflected by the rejection filter in the direction of irradiating the sample. The monochromatic excitation light beam, after being reflected by the rejection filter, is focused at the end of an objective lens placed in the optical path, and is focused and irradiated onto the sample placed on the XY stage of a composite stage apparatus, which is a combination of an XY stage and a Z stage. The monochromatic excitation light beam reflected or scattered by the sample travels backward to the first beam splitter, is reflected, and enters an AF control unit positioned in the reflection direction. The AF control unit performs the necessary calculations to determine the positional misalignment between the focal point of the objective lens and the sample, and raises or lowers the Z-stage to correct the misalignment. Furthermore, when a monochromatic excitation light beam is incident on the sample, the Rayleigh scattered light and Raman scattered light from the sample that passes through the rejection filter are guided to a spectrometer to spectrally analyze at least the Raman scattered light, and the spectrally analyzed light is detected by a detector. A movable reflector is positioned in the optical path after the Rayleigh scattered light and the Raman scattered light have passed through the rejection filter. This reflector is switched between a state where it intersects the sample surface at a required angle during surface observation and a state where it is removed from the optical path when not being observed. An illumination lamp that emits illumination light for observing the surface of the sample, the illumination lamp reflects the illumination light with a second beam splitter and a movable reflector, and transmits it through a rejection filter and an objective lens to illuminate the sample, and an observation camera that photographs the reflected light that reflects the surface shape of the sample, which has been reflected by the illumination light from the sample, and which has traveled back to the second beam splitter and transmitted through, The laser oscillators are arranged in multiple units to emit monochromatic excitation light beams of different wavelengths, and the rejection filters are arranged in multiple units having the required high reflectivity corresponding to each wavelength of the monochromatic excitation light beams of the multiple laser oscillators. One of the multiple laser oscillators is configured to emit a monochromatic excitation light beam, and one of the multiple rejection filters is selected one-to-one with the laser oscillator, and the selected rejection filter is moved alternately to the predetermined position. The system is designed to be controlled entirely by a PC. A laser Raman microscope characterized by the following features. [Claim 2] The laser Raman microscope according to claim 1, wherein the plurality of laser oscillators are fixedly arranged, and a monochromatic excitation light beam emitted from one of the selected laser oscillators is incident on the alignment mirror via a plurality of mirrors in the same optical path. [Claim 3] The laser Raman microscope according to claim 1, wherein a plurality of the laser oscillators are arranged on a movable table, and by scanning the movable table, one of the laser oscillators is selected and moved to the oscillation position, and the monochromatic excitation light beam emitted from the selected laser oscillator is incident on the alignment mirror in the same optical path. [Claim 4] The laser Raman microscope according to claim 1, wherein the AF control unit is configured to calculate the positional misalignment between the focal point of the objective lens and the sample using one of the following methods: pupil division method, knife edge method, optical path difference pinhole method, Foucault method, critical angle method, phase difference method, and astigmatism method. [Claim 5] The laser Raman microscope according to claim 4, wherein the AF control unit includes a blade, a lens, a detector, a calculation unit, and a motor driver, and the blade partially blocks the light beam, and the calculation unit performs the necessary calculations based on the detection position of the monochromatic excitation light beam on the detector to calculate the positional misalignment between the focal point of the objective lens and the sample, and the motor driver drives the Z stage up or down to correct the positional misalignment. [Claim 6] The laser Raman microscope according to claim 1, wherein the spectrometer is configured to perform spectroscopy of Raman scattered light by diffraction grating, filter, or Fourier transform. [Claim 7] The laser Raman microscope according to claim 1, further comprising means for controlling the distance between the sample and the objective lens, which is capable of complementing the control range of the AF control unit, in addition to the AF control unit.

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