JP2008040154A - Confocal laser scanning microscope - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a confocal laser scanning microscope capable of obtaining high detection accuracy and high focus detecting sensitivity related to a sample, without being affected by a pupil diameter difference between objective lenses having different magnification. <P>SOLUTION: The confocal laser scanning microscope includes: a laser light source 1; a polarized beam splitter (PBS) 3; a plurality of beam expanders 17; a two-dimensional scanning mechanism 4; a pupil projection lens 5; an image forming lens 6; a 1/4 wavelength plate 7; an objective 9; a stage 12; an image forming lens 13; a pinhole 14; and an optical detector 15. The beam expander 17 is configured to change the beam diameter of the incident laser beam 2 to substantially the same as the diameter of the pupil 8 of the objective 9 arranged on the optical path. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a confocal laser microscope for measuring and observing sample height information.

  For example, in the industrial inspection field, a confocal laser microscope is an effective device for measuring and observing the height information of a sample such as a wafer placed on a stage, and obtains an image of a very high contrast sample. Can do.

  A configuration of a general confocal laser microscope will be described with reference to FIGS.

  FIG. 6 is a schematic configuration diagram of a general confocal laser microscope.

  The confocal laser microscope is provided with a laser light source 1 as an illumination light source. The laser light source 1 emits a laser beam 2 having linear polarization characteristics. On the optical path of the laser beam 2, a polarization beam splitter (PBS) 3 and a two-dimensional scanning mechanism 4 that rotates and deflects the laser beam 2 to scan on the sample 11 are sequentially arranged. The two-dimensional scanning mechanism 4 is disposed at a position conjugate with a pupil 8 of an objective lens 9 described later. Below the two-dimensional scanning mechanism 4, a pupil projection lens 5, an imaging lens 6, a quarter wavelength plate 7, an objective lens 9, and a sample 11 placed on a stage 12 are sequentially arranged. Below the polarization beam splitter 3, a photodetector 15 having an imaging lens 13, a pinhole 14, and a light receiving surface 16 is sequentially arranged. The pinhole 14 is disposed at a position conjugate with the imaging position of the laser beam 2 that has passed through the objective lens 9.

  The laser beam 2 is received by the light receiving surface 16 without being blocked by the pinhole 14 only when an image is formed on the sample 11 by the objective lens 9. Therefore, the confocal laser microscope can reduce flare light as compared with a normal microscope, and an observer can obtain an image with high resolution, high contrast, and shallow depth of focus.

  By the way, in the case of a confocal laser microscope, the degree of the confocal effect varies depending on the hole diameter of the pinhole 14. The smaller the hole diameter of the pinhole 14, the stronger the confocal effect, and the observer can obtain an image with high resolution, high contrast, and shallow depth of focus. However, even if the hole diameter of the pinhole 14 is reduced due to the NA of the objective lens 9 or the wavelength of the laser beam 2, there is a limit to improving the resolution.

  Next, the configuration of a general confocal laser microscope system will be described with reference to FIG.

  The instruction unit 35 outputs an instruction signal for moving at least one of the revolver 10 or the stage 12 in the optical axis direction of the laser beam 2 to the control unit 32 in order to adjust the relative distance between the objective lens 9 and the sample 11. The control unit 32 receives this signal and outputs a drive (control) signal for driving at least one of the revolver 10 and the stage 12 to the drive mechanism. In response to this control signal, the drive mechanism moves at least one of the revolver 10 or the stage 12. As a result, the relative distance is adjusted.

  For example, when the observer selects the objective lens 9 to be used in the instruction unit 35, the instruction unit 35 sends a control signal for arranging the objective lens 9 to be used on the optical path of the laser beam 2 via the control unit 32. Output to the revolver 10. As a result, the revolver 10 is electrically rotated to place the objective lens 9 on the optical path.

  When the reflected light from the sample 11 is received by the light receiving surface 16, the photodetector 15 outputs a detection signal that changes according to the intensity of the reflected light to the calculation unit 31. The calculation unit 31 processes this detection signal as luminance information.

  The calculation unit 31 samples the detection signal through the control unit 32 at a constant period while synchronizing with the scanning position of the two-dimensional scanning mechanism 4 to construct an observation image. On the display unit 34, an observation image constructed by the calculation unit 31 is displayed. This observation image is stored in the memory 33. The calculation unit 31 can also read the stored observation image later and display it on the display unit 34.

  The confocal laser microscope is provided with a plurality of objective lenses 9 as described above. Generally, the diameter of the pupil 8 of the objective lens 9 is different depending on the magnification of the objective lens 9. When the revolver 10 holds a plurality of objective lenses, the diameter of the laser beam 2 needs to satisfy the pupils 8 of all objective lenses 9 in order to maximize the performance of the objective lens 9.

  For example, it is assumed that the observer switches to another objective lens 9 when the diameter of the laser beam 2 is substantially the same as the diameter of the pupil 8 of the objective lens 9 having the largest diameter among the plurality of objective lenses 9. At the time of switching, if the diameter of the pupil 8 of the switched objective lens 9 is smaller than the diameter of the laser beam 2 described above, a part of the laser beam 2 is vignetted by the pupil 8 of the objective lens 9. As a result, sufficient laser beam 2 does not enter the objective lens 9, and as a result, the amount of light of the laser beam 2 imaged on the sample 11 decreases, and the S / N of the observation image deteriorates.

Further, when the image is formed on the sample 11 as described above, the diameter of the laser beam 2 reflected from the sample 11 and transmitted through the pupil 8 of the objective lens 9 is substantially the same as the diameter of the pupil 8 of the objective lens 9. .
Therefore, the diameter of the laser beam 2 incident on the imaging lens 13 changes every time the observer switches the objective lens 9. As a result, the spot diameter of the laser beam 2 imaged by the imaging lens 13 is also changed, so that the confocal effect of the observation image is changed by the objective lens 9.

  Thereby, as described above, when the light amount of the laser beam 2 decreases, the light amount received by the light receiving surface 16 also changes. Therefore, the S / N of the observation image is deteriorated and the detection accuracy is also lowered.

  Further, for example, when the diameter of the pupil 8 of the objective lens 9 is smaller than the diameter of the laser beam 2 described above, it is sufficient that the hole diameter of the pinhole 14 is relatively large. However, when the diameter of the pupil 8 of the objective lens 9 is larger than the diameter of the laser beam 2 described above, the hole diameter of the pinhole 14 needs to be reduced.

  As a means for changing the beam diameter of the laser beam 2, there is a beam expander. By arranging this beam expander on the optical path, the beam diameter of the laser beam 2 can be enlarged or reduced to be substantially the same as the diameter of the pupil 8 of the objective lens 9.

Patent Documents 1 to 3 disclose a confocal laser microscope in which a beam expander is arranged.
JP-A-7-63508 JP-A-7-12525 Japanese Patent Laid-Open No. 9-251128

  The beam expanders disclosed in Patent Document 1 to Patent Document 3 described above are only arranged on the optical path. Therefore, for example, when the revolver holds a plurality of objective lenses 9 having different magnifications, the beam expander cannot change the diameter of the laser beam 2 in accordance with the diameters of the pupils 8 of all the objective lenses 9.

There is also a confocal laser microscope that can adjust the confocal effect of the observation image by making the hole diameter of the pinhole 14 variable.
In this case, it is possible to improve the contrast and resolution of the observation image by adjusting the confocal effect, but the limit value of the resolution of the optical member of the microscope is determined by the NA of the objective lens 9 and the wavelength of the laser beam 2. Even if the hole diameter of the hole 14 is variable, the resolution cannot be improved beyond the limit value. Further, it is not easy to adjust the hole center of the pin hole 14 having a minute hole diameter to the optical axis center position.

  In view of the above problems, in the present invention, means for changing or enlarging the diameter of the laser beam substantially the same as the diameter of the pupil of the objective lens arranged on the optical path is provided. A confocal laser microscope capable of obtaining an image with high resolution is provided.

  In order to achieve the object, the present invention provides a light source that emits a laser beam, a two-dimensional scanning mechanism that scans a sample by deflecting the laser beam emitted from the light source, and a laser beam deflected by the two-dimensional scanning mechanism. A plurality of objective lenses that form an image on the sample, a beam splitter that is disposed between the light source and the two-dimensional scanning mechanism, transmits the laser beam emitted from the light source, and reflects the reflected light reflected from the sample; A confocal laser microscope comprising: a light receiving unit that receives reflected reflected light; and a calculation unit that calculates height information of the sample based on the intensity of the reflected light received by the light receiving unit. A beam that is arranged between two-dimensional scanning mechanisms and changes the diameter of the laser beam that passes through the beam splitter in accordance with the objective lens that is arranged on the optical path. Providing a confocal laser microscope characterized by comprising a changing unit.

  According to the present invention, the S / N is improved by changing or enlarging the diameter of the laser beam to be substantially the same as the diameter of the pupil of the objective lens arranged on the optical path, and an image with an optimum contrast and high resolution can be obtained. A confocal laser microscope that can be obtained can be provided.

Hereinafter, a first embodiment according to the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a confocal laser microscope according to the present embodiment. FIG. 2 is a diagram showing a configuration of a confocal laser microscope system. The same components as those in FIGS. 6 and 7 described above are denoted by the same reference numerals, and detailed description thereof is omitted. The optical path of the laser beam 2 shown in FIG. 1 indicates the optical path at the center and end of the deflection range when the laser beam 2 is deflected by the two-dimensional scanning mechanism 4.

  Similar to the arrangement shown in FIG. 6 described above, the laser light source 1 that emits the laser beam 2 and the laser beam 2 emitted from the laser light source 1 are transmitted through the optical path of the confocal laser microscope. A polarizing beam splitter (PBS) 3 that reflects reflected light downward and a two-dimensional scanning mechanism 4 that rotates and deflects the laser beam 2 to scan the sample 11 are sequentially arranged. The optical path of the laser beam 2 is branched by the polarization beam splitter 3. The two-dimensional scanning mechanism 4 is disposed at a position conjugate with a pupil 8 of an objective lens 9 described later.

  Below the two-dimensional scanning mechanism 4, there are a pupil projection lens 5, an imaging lens 6, a quarter-wave plate 7, a revolver 10 that holds a plurality of objective lenses 9 (three in this embodiment), and a sample 11. Are placed in sequence. Further, below the polarizing beam splitter (PBS) 3, a photodetector 15 having an imaging lens 13, a pinhole 14, and a light receiving surface 16 is sequentially arranged.

  The observer can place any one of the objective lenses 9 having different magnifications on the optical path by rotating the revolver 10 manually or electrically. The observer can select the objective lens 9 according to the sample 11. As described above, the revolver 10 is an objective lens placement unit that places any one of the objective lenses 9 on the optical path.

  Further, at least one of the revolver 10 and the stage 12 is provided with a drive mechanism (not shown). This drive mechanism moves at least one of the revolver 10 and the stage 12 along the optical axis. Therefore, the drive mechanism adjusts the relative distance between the objective lens 9 and the sample 11 arranged on the optical axis. The drive mechanism moves at least one of the revolver 10 and the stage 12 regardless of the shape of the sample 11 (adjusts the relative distance) to focus. Thereby, the laser beam 2 can form an image on the sample 11.

  On the optical path of the laser beam 2 and between the polarization beam splitter (PBS) 3 and the two-dimensional scanning mechanism 4, a beam diameter changing portion which is a feature of the present invention is fixedly arranged. The beam diameter changing unit holds a beam expander 17 that is a beam expander for expanding the beam diameter and a plurality of beam expanders 17 having different expansion ratios, and any one of the beam expanders 17 is placed on the optical path. A beam expander revolver 18 is provided as a beam expander arrangement portion to be arranged.

  The beam expander 17 expands the diameter of the laser beam 2 so as to be substantially the same as the diameter of the pupil 8 of the objective lens 9 arranged on the optical path. Specifically, when the objective lens 9 disposed on the optical path is switched by the rotation of the revolver 10, the diameter of the pupil 8 of the objective lens 9 disposed on the optical path is substantially the same as the beam diameter of the laser beam 2. A beam expander 17 having a magnification to be arranged is arranged on the optical path by a beam expander revolver 18. Therefore, the magnification of each beam expander is different. Therefore, the beam diameter of the laser beam 2 transmitted through the beam expander 17 in this embodiment is always substantially the same as the diameter of the pupil 8 of the objective lens 9. As a result, the laser beam 2 that always satisfies the NA of the objective lens 9 is incident on the objective lens 9. Since the beam expander 17 and the objective lens 9 in the present embodiment have a one-to-one correspondence, the same number (three) of beam expanders 17 as the objective lens 9 are held in the beam expander revolver 18. .

  Next, the configuration of the system of the confocal laser microscope in this embodiment will be described with reference to FIG.

  The system 30 of the confocal laser microscope in the present embodiment is provided with a calculation unit 31, a control unit 32, a memory 33, a display unit 34, and an instruction unit 35 as in FIG.

  Since these parts have the same configuration and operation as the parts shown in FIG. 7 described above, only the features of this embodiment will be described below.

  As described above, the diameter of the laser beam 2 is enlarged by the beam expander 17 to be substantially the same as the diameter of the pupil 8 of the objective lens 9 arranged on the optical path. Therefore, a combination of the beam expanders 17 corresponding to the objective lens 9 is stored in the memory 33 in advance. In this combination, the magnification information of the objective lens 9 and the diameter of the laser beam 2 are enlarged so that the diameter of the laser beam 2 is substantially the same as the diameter of the pupil 8 of the objective lens 9 arranged on the optical path. This is a combination of magnification information of the beam expander 17.

  Next, an operation method of the confocal laser microscope in this embodiment will be described.

  In this system, the observer instructs the instruction unit 35 to place the objective lens 9 used for observation on the optical path. As a result, the instruction unit 35 outputs a control signal for arranging the objective lens 9 to be used on the optical path of the laser beam 2 to the revolver 10 via the control unit 32. As a result, the revolver 10 is electrically rotated to place the objective lens 9 on the optical path. At the same time, the control unit 32 reads out magnification information of the beam expander 17 corresponding to the selected objective lens 9 from the combination information stored in the memory 33.

  The control unit 32 outputs a control signal to the beam expander revolver 18 so that the beam expander 17 having the read magnification information is arranged on the optical path. After receiving the control signal, the beam expander revolver 18 rotates to place the beam expander 17 on the optical path.

  When the observer manually switches the objective lens 9, a detection unit (not shown) detects the objective lens 9 disposed on the optical path, and outputs magnification information corresponding to the objective lens 9 to the control unit 32. The control unit 32 receives this magnification information and refers to the memory 33. The referred control unit 32 reads out the beam expander 17 corresponding to the objective lens 9 arranged on the optical path from the combination information stored in the memory 33.

  The control unit 32 outputs a control signal to the beam expander revolver 18 so that the read beam expander 17 is arranged on the optical path. After receiving the control signal, the beam expander revolver 18 rotates to place the beam expander 17 on the optical path.

  The observer may directly manually rotate the revolver 10 and the beam expander revolver 18.

  Further, the observer adjusts the relative distance between the objective lens 9 and the sample 11 by the drive mechanism via the instruction unit 35 and the control unit 32 as described above.

  The diameter of the laser beam 2 emitted from the laser light source 1 is substantially the same as the diameter of the pupil 8 of the objective lens 9 disposed on the optical path by passing through the beam expander 17. The laser beam 2 whose diameter is expanded by the beam expander 17 is incident on the two-dimensional scanning mechanism 4. The optical path of the laser beam 2 shown in FIG. 1 indicates the optical path of the center and one end of the deflection range when the laser beam 2 is deflected by the two-dimensional scanning mechanism 4.

  The laser beam 2 deflected by the two-dimensional scanning mechanism 4 passes through the pupil projection lens 5, the imaging lens 6, the quarter wavelength plate 7, the pupil 8 of the objective lens 9, and the objective lens 9 arranged on the optical path. To Penetrate. The transmitted laser beam 2 is imaged on the sample 11 placed on the stage 12 by the objective lens 9.

  The diameter of the laser beam 2 is substantially the same as the diameter of the pupil 8 of the objective lens 9 by the beam expander 17. Therefore, the laser beam 2 is not vignetted by the pupil 8 of the objective lens 9 and is irradiated onto the sample 11 without reducing the light amount. In addition, since the NA of the objective lens 9 is sufficiently satisfied in the laser beam 2, the resolution of the objective lens 9 can be fully exhibited.

  The laser beam 2 having the characteristic of linearly polarized light is converted into circularly polarized light by passing through the quarter wavelength plate 7. The converted laser beam 2 forms an image on the sample 11 by the objective lens 9 and generates a spot-like light by diffraction.

  The above-described point-like light is two-dimensionally scanned on the sample 11 by the two-dimensional scanning mechanism 4. This scanning range depends on the fluctuation width of the laser beam 2 deflected by the two-dimensional scanning mechanism 4.

  The laser beam 2 (reflected light) reflected from the sample 11 passes through the objective lens 9 and the quarter wavelength plate 7.

  The laser beam 2 having circularly polarized characteristics is converted into linearly polarized light again by passing through the quarter wavelength plate 7. The laser beam 2 converted into linearly polarized light has a characteristic of linearly polarized light orthogonal to the laser beam 2 emitted from the laser light source 1.

  The laser beam 2 that has passed through the quarter-wave plate 7 is imaged by the imaging lens 6. After the image formation, the laser beam 2 passes through the pupil projection lens 5 and enters the polarization beam splitter 3 via the two-dimensional scanning mechanism 4 and the beam expander 17.

  In this way, the laser beam 2 enters the polarization beam splitter 3 through the exact same path as when it enters the sample 11. The laser beam 2 is converted into linearly polarized light again by passing through the quarter wavelength plate 7 and is orthogonal to the laser beam 2 having the characteristics of linearly polarized light emitted from the laser light source 1. Therefore, the laser beam 2 incident on the polarization beam splitter 3 is reflected by the polarization beam splitter 3.

  The laser beam 2 reflected by the polarization beam splitter 3 is guided to the imaging lens 13. In addition, since the two-dimensional scanning mechanism 4 is arranged at a position conjugate with the pupil position of the objective lens 9, the laser beam 2 moves on the imaging lens 13 even if the two-dimensional scanning mechanism 4 scans off-axis. Absent.

  The laser beam 2 is focused in a dot shape by the imaging lens 13 and passes through the pinhole 14. As described above, the pinhole 14 is disposed at a position conjugate with the imaging position of the laser beam 2 that has passed through the objective lens 9.

  The beam diameter of the laser beam 2 (reflected light) incident on the imaging lens 13 via the polarization beam splitter 3 is the beam diameter of the laser beam 2 emitted from the laser light source 1 by passing through the beam expander 17. And reduced to be substantially the same. Therefore, in this embodiment, the spot diameter of the laser beam 2 imaged by the imaging lens 13 is always constant without being influenced by the objective lens 9. Therefore, in this embodiment, if the pinhole 14 having the optimum hole diameter is arranged, it is not necessary to change the hole diameter of the pinhole 14 and the laser beam 2 is not shielded by the pinhole 14. The light passes through the pinhole 14 and is received by the light receiving surface 16.

  When the laser beam 2 is received by the light receiving surface 16, the photodetector 15 detects the light intensity of the laser beam 2 as luminance information. After detection, height information is calculated based on the detection result. As a result, an observation image having a confocal effect is constructed. Since the laser beam 2 received by the light receiving surface 16 is not vignetted by the pupil 8 of the objective lens 9, the amount of light does not decrease at the light receiving surface 16 compared to when it is emitted from the laser light source 1. .

  Since the spot diameter of the laser beam 2 is always constant, the observer can always obtain an observation image with high S / N, high contrast, and high resolution.

  Next, a method for capturing the three-dimensional image data of the sample 11 by the confocal laser microscope will be described.

  This capturing method is performed when the observer outputs an instruction from the instruction unit 35 to the calculation unit 31 via the control unit 32.

  When the calculation unit 31 captures the three-dimensional image data of the sample 11 into the memory 33, the confocal laser microscope performs the two-dimensional scanning on the observation surface of the sample 11 by the two-dimensional scanning mechanism 4 and the relative distance by the driving mechanism described above. Adjustments need to be made.

  The observer rotates the revolver 10 manually or with the instruction unit 35 as described above, and arranges the objective lens 9 used for observation on the optical path. At that time, the sample is irradiated with the laser beam 2 in a spot shape. Then, the laser beam 2 is scanned on the sample 11 by the two-dimensional scanning mechanism 4, and the reflected light from the sample 11 is received by the light receiving surface 16. The photodetector 15 outputs the detected luminance information to the calculation unit 31. And the calculating part 31 calculates height information based on luminance information, and constructs | assembles an observation image using luminance information.

  Next, the control unit 32 adjusts the relative distance between the objective lens 9 and the sample 11 by the driving mechanism as described above, and the two-dimensional scanning mechanism 4 scans the sample 11 again with the laser beam 2. And the calculating part 31 constructs | assembles the observation image in this position.

  The process of adjusting the position of the driving mechanism is repeatedly performed until the scanning range of the two-dimensional scanning mechanism 4 passes over the sample 11 and fills the height of the sample 11 (Z direction).

  By adjusting in this way, the calculation unit 31 has each Z position (relative distance between the objective lens 9 and the sample 11) at the XY position (scanning direction of the laser beam 2 by the two-dimensional scanning mechanism 4) on the observation surface of the sample 11. Brightness information can be obtained. The calculation unit 31 can regard the Z position at which the maximum luminance value is detected by the light receiving surface 16 at the XY position as the focus position on the sample 11 (calculate height information). Thereby, the calculating unit 31 constructs a three-dimensional image of the sample 11.

  Thus, in the present embodiment, the diameter of the laser beam 2 emitted from the laser light source 1 by the beam expander 17 having different magnifications is substantially the same as the diameter of the pupil 8 of the objective lens 9 arranged on the optical path. Can be expanded.

  Therefore, in the present embodiment, the laser beam 2 that always satisfies the NA of the objective lens 9 can be incident on the objective lens 9 without being affected by the difference in the diameter of the pupil 8 of the objective lens 9 having different magnifications. Since the laser beam 2 is not vignetted by the pupil 8 of the objective lens 9, the present embodiment can irradiate the sample 11 with the laser beam 2 without reducing the amount of light. Further, since the NA of the objective lens 9 is sufficiently filled in the laser beam 2, the resolution of the objective lens 9 can be sufficiently exhibited.

  The beam expander 17 is disposed between the polarization beam splitter 3 and the two-dimensional scanning mechanism 4. Therefore, the beam diameter of the laser beam 2 incident on the imaging lens 13 is always substantially the same as the beam diameter of the laser beam 2 emitted from the laser light source 1. As described above, the laser beam 2 is irradiated on the sample 11 without being vignetted by the beam expander 17, then enters the imaging lens 13, and is received by the light receiving surface 16. Therefore, the observer can obtain an observation image with good S / N, optimum contrast, and high resolution without being affected by the difference in the diameter of the pupil 8 of the objective lens 9.

  The confocal effect of the observation image is adjusted from the relative relationship between the hole diameter of the pinhole 14 and the spot diameter of the laser beam 2 imaged by the imaging lens 13. The spot diameter of the laser beam 2 imaged by the imaging lens 13 is determined by the diameter of the laser beam 2 incident on the imaging lens 13. The diameter of the laser beam 2 in this embodiment is substantially the same as the pupil 8 of the objective lens 9 as described above without being affected by the objective lens 9. Therefore, this embodiment can always obtain an observation image having the same confocal effect.

  Therefore, the optimum confocal effect can be exhibited by combining the focal length of the imaging lens 13, the diameter and wavelength of the laser beam 2, and the hole diameter of the pinhole 14 in advance. In this case, it is not necessary to adjust the diameter of the pinhole described above, and the confocal effect is always optimized without being affected by the objective lens 9, and an observation image with high resolution and high contrast can be acquired. .

  Further, the beam expander 17 for expanding the beam diameter of the laser beam 2 can be switched by the beam expander revolver 18 and the objective lens 9 disposed on the optical path by the system 30. The form can arrange | position the beam expander 17 on an optical path simply.

  Further, when the laser beam 2 is incident on the pupil 8 of the objective lens 9, the diameter of the laser beam 2 is made to satisfy the diameter of the pupil 8 of the objective lens 9 by the beam expander 17. An observation image can be obtained.

  The depth of focus also depends on the NA of the laser beam 2 imaged from the objective lens 9, and the greater the NA, the shallower the depth of focus and the better the resolution in the Z direction.

  The confocal effect of the confocal laser microscope depends on the relative relationship between the hole diameter of the pinhole 14 and the spot diameter of the laser beam 2 imaged by the imaging lens 13. The diameter of the laser beam 2 imaged by the imaging lens 13 is always the same as the diameter of the laser beam 2 emitted from the laser light source 1 by the beam expander 17. Therefore, if the pinhole 14 having an optimum hole diameter corresponding to this diameter is arranged, the confocal effect is increased. Therefore, the resolution and contrast in the XY direction of the observation image are improved.

  In this embodiment, as shown in FIG. 2, three objective lenses 9 and three beam expanders 17 are arranged and have a one-to-one correspondence. However, it is necessary to limit this number and the one-to-one correspondence. No. For example, both may be 5 or 6. In addition, when the beam expander revolver 18 holds a plurality of beam expanders 17, a state without the beam expander 17 (perforated state) may be formed. In this case, the diameter of the laser beam 2 is guided to the two-dimensional scanning mechanism 4 without being enlarged (enlargement magnification is 1).

  Next, a second embodiment according to the present invention will be described in detail with reference to FIGS. 3 (a) and 3 (b). The same parts as those in the first embodiment described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 3A and FIG. 3B are schematic views when a part of the beam diameter variable portion moves on the optical path.

  The beam diameter changing unit in this embodiment does not have the beam expander 17 and the beam expander revolver 18 as compared with the first embodiment described above.

  In the beam diameter changing unit in the present embodiment, a beam diameter varying unit 19 is disposed between the polarization beam splitter 3 and the two-dimensional scanning mechanism 4 on the optical path. The beam diameter variable unit 19 can change the diameter of the incident laser beam 2 to be substantially the same as the diameter of the pupil 8 of the objective lens 9 arranged on the optical path. The beam diameter variable unit 19 can change the diameter of the laser beam 2 by adjusting the relative distance between the optical members (the fixed optical member 19a, the fixed optical member 19b, and the movable optical member 19c) provided therein. It is.

  Next, the configuration of the beam diameter variable unit in the present embodiment will be described.

  The beam diameter variable unit 19 is provided with a fixed optical member 19a, a fixed optical member 19b, a movable optical member 19c, a fixed optical member back 19d, and a servo motor drive unit 19e. The fixed optical member 19a, the fixed optical member 19b, and the movable optical member 19c are lenses.

  The fixed optical member 19a and the fixed optical member 19b are held by the fixed optical member back 19d. The arrangement positions of the fixed optical member 19a and the fixed optical member 19b are fixed.

  As shown in FIGS. 3A and 3B, the movable optical member 19c is moved along the optical axis by a servo motor driving unit 19e which is an optical member adjusting unit. As a result, the relative distance between the fixed optical member 19a and the movable optical member 19c and the fixed optical member 19b and the movable optical member 19c are adjusted. This adjustment is performed so that the diameter of the laser beam 2 is substantially the same as the diameter of the pupil 8 of the objective lens 9 disposed on the optical path for use by the observer for observation. This is done to make it variable.

  Therefore, a combination of the objective lens 9 and the arrangement position of the movable optical member 19c corresponding to the objective lens 9 is stored in the memory 33. This combination means that the magnification information of the objective lens 9 and the position of the movable optical member 19c in the optical axis direction that makes the diameter of the laser beam 2 substantially the same as the diameter of the pupil 8 of the objective lens 9 arranged on the optical path. It is a combination of information.

  Next, an operation method of the confocal laser microscope in this embodiment will be described.

  In this system, the observer instructs the instruction unit 35 to place the objective lens 9 used for observation on the optical path. As a result, the instruction unit 35 outputs a control signal for arranging the objective lens 9 to be used on the optical path of the laser beam 2 to the revolver 10 via the control unit 32. As a result, the revolver 10 is electrically rotated to place the objective lens 9 on the optical path. At the same time, the control unit 32 reads out arrangement position information in the optical axis direction of the movable optical member 19c corresponding to the selected objective lens 9 from the combination information stored in the memory 33.

  The control unit 32 outputs a control signal to the servo motor driving unit 19e so as to arrange the movable optical member 19c at the read arrangement position. After receiving the control signal, the servo motor drive unit 19e moves and arranges the movable optical member 19c along the optical axis (the relative distance between the optical members is adjusted).

  In the present embodiment, a laser scale is mounted on the servo motor drive unit 19e, and the position can be adjusted by a feedback circuit.

  The observer can also manually set the arrangement position of the movable optical member 19c, and can also arbitrarily set the arrangement position of the movable optical member 19c manually or electrically. Thereby, the diameter of the laser beam can be finely adjusted freely.

  As described above, the present embodiment can obtain the same effects as those of the first embodiment described above. Furthermore, since this embodiment can freely variably adjust the diameter of the laser beam, it can be applied to various types of objective lenses 9. By arranging the beam diameter variable unit 19 without mounting the beam expander revolver 18, it is possible to make the entire apparatus compact. In the first embodiment described above, the beam expander 17 and the objective lens 9 have a one-to-one correspondence. However, in the present embodiment, one beam diameter variable unit 19 supports a plurality of objective lenses 9. It is also possible to do.

  Next, a third embodiment according to the present invention will be described in detail with reference to FIGS. 4 (a), 4 (b), 5 (a), and 5 (b). The same parts as those in the first embodiment described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  4A and 4B are half sectional views of the correction ring objective lens. FIG. 5A is an inner development view of the adjustment ring. FIG. 5B is an outside development view of the adjustment ring.

  In the present embodiment, the revolver 10 is not provided in the confocal laser laser microscope as compared with the first and second embodiments described above.

  Therefore, in this embodiment, the correction ring objective lens 21 is arranged on the optical path. The correction ring objective lens 21 includes a plurality of optical members and an adjustment unit that adjusts the relative distance between the optical members. The correction ring objective lens 21 changes the lens performance by adjusting the relative distance between the optical members. The change in lens performance includes, for example, correction of aberration and change in lens magnification.

  The correction ring objective lens 21 is mounted on a confocal laser microscope when the wavelength of the laser beam 2 has a wavelength in the near infrared region of 1100 nm to 1600 nm and the sample 11 is a silicon wafer, for example. The observer switches the beam expander 17 in accordance with the adjustment of the relative distance of the optical member in the correction ring objective lens 21.

  Next, the configuration of the correction ring objective lens in the present embodiment will be described.

  The correction ring objective lens 21 includes a fixed optical member 21a, which is an optical member, a fixed optical member 21b, three movable optical members 21c, a fixed optical member member 21d which is an adjustment unit, a fixed optical member member 21e, and a movable optical member member. 21f, an adjustment ring 21g, and a correction ring objective lens cover 21h are provided. The fixed optical member 21a, the fixed optical member 21b, and the movable optical member 21c are lenses.

The fixed optical member 21a is held by the fixed optical member work 21d, and the arrangement position is fixed.
The fixed optical member 21b is held by the fixed optical member work 21e, and the arrangement position is fixed.
The movable optical member 21c is held by the movable optical member back 21f. This movable optical member 21f is held by the adjustment ring 21g. The movable optical member 21c is movable between the fixed optical member 21a and the fixed optical member 21b by the movable optical member ring 21f and the adjustment ring 21g. Thereby, the relative distances of the fixed optical member 21a, the fixed optical member 21b, and the movable optical member 21c are adjusted.

The adjustment ring 21g has a ring shape. An inclined portion 21i is provided on the inner surface of the adjusting ring 21g as shown in FIG. The movable optical member 21f is placed on the inclined portion 21i. A memory 21j is provided on the outer surface of the adjustment ring 21g as shown in FIG.
Note that the interval between the movable optical members 21c is not variable.

  When the adjustment ring 21g is rotated, the placement position of the movable optical member wax 21f on the inclined portion 21i is changed. For example, when the movable optical member wax 21f moves from the low part to the high part of the inclined part 21i, the movable optical member wax 21f moves from the state shown in FIG. 4 (a) to the state shown in FIG. 4 (b). As a result, the movable optical member 21c moves along the optical axis.

  When the observer moves the movable optical member 21c along the optical axis, the observer adjusts the position of the movable optical member 21c by adjusting the rotation amount of the adjustment ring 21g using the memory 21j as an index.

  When the arrangement position of the movable optical member 21c is adjusted in this way, the NA of the correction ring objective lens 21 and the diameter of the pupil of the correction ring objective lens 21 change.

  In the present embodiment, as described above, the diameter of the laser beam 2 and the diameter of the pupil of the corrected annulus objective lens 21 need to be substantially the same. Therefore, in this embodiment, it is necessary to arrange on the optical path the beam expander 17 that makes the diameter of the laser beam 2 and the diameter of the pupil substantially the same in accordance with the arrangement position of the movable optical member 21c.

  Therefore, a combination of the correction ring adjustment value (arrangement position of the movable optical member 21 c) of the correction ring objective lens 21 and the magnification information of the beam expander 17 corresponding to the correction ring adjustment value is stored in the memory 33. When the observer adjusts the arrangement position of the movable optical member 21 c electrically, the observer inputs the correction ring adjustment value of the correction ring objective lens 21 to the instruction unit 35. Upon receiving the input, the control unit 32 rotates the adjustment ring 21g to adjust the arrangement position of the movable optical member 21c. At the same time, the control unit 32 reads out magnification information of the beam expander 17 corresponding to the input correction ring adjustment value of the correction ring objective lens 21 from the combinations stored in the memory 33. The control unit 32 outputs an instruction signal to the beam expander revolver 18 based on this information. After receiving the instruction signal, the beam expander revolver 18 arranges the beam expander 17 corresponding to the correction ring adjustment value on the optical path.

  Thus, in this embodiment, the observer rotates the adjustment ring 21g to adjust the relative distances of the fixed optical member 21a, the fixed optical member 21b, and the movable optical member 21c. Thereby, the same effect as the first and second embodiments described above can be obtained. In addition, since the lens performance can be changed, the aberration of the laser beam 2 can be corrected and the magnification of the objective lens can be adjusted.

  In the present embodiment, the beam expander revolver 18 may be manually rotated as in the first embodiment.

  Further, as in the second embodiment described above, the beam expander 19 may be mounted without mounting the beam expander revolver 18.

  In the present embodiment, the correction ring objective lens 21 is used. However, for example, an objective lens having a zoom function may be arranged on the optical path. Therefore, this objective lens can adjust the lens magnification by itself. Such an objective lens has the same configuration as that shown in FIGS. 4 (a) and 4 (b). That is, optically, a fixed lens whose position is fixed, a movable lens whose position can be adjusted, and an adjustment member that adjusts the position of the movable lens may be provided. Then, the beam expander 17 and the like may be arranged in accordance with the lens magnification.

It is a schematic block diagram of the confocal laser microscope of this embodiment which concerns on 1st Embodiment. It is a figure shown about the system configuration | structure of a confocal laser microscope. FIG. 3A and FIG. 3B are schematic views when the beam diameter varying unit in the second embodiment moves on the optical path. 4A and 4B are half cross-sectional views of a correction ring objective lens according to the third embodiment. FIG. 5A is an inner development view of the adjustment ring. FIG. 5B is an outside development view of the adjustment ring. The schematic block diagram of a common confocal laser microscope is shown. It is a figure shown about the structure of the system of a general confocal laser microscope.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Laser light source, 2 ... Laser beam, 3 ... Polarization beam splitter, 4 ... Two-dimensional scanning mechanism, 5 ... Pupil projection lens, 6 ... Imaging lens, 7 ... 1/4 wavelength plate, 8 ... Pupil, 9 ... Objective Lenses, 10 ... revolver, 11 ... sample, 12 ... stage, 13 ... imaging lens, 14 ... pinhole, 15 ... photodetector, 16 ... light receiving surface, 17 ... beam expander, 18 ... revolver for beam expander, DESCRIPTION OF SYMBOLS 19 ... Beam diameter variable part, 19a ... Fixed optical member, 19b ... Fixed optical member, 19c ... Movable optical member, 19d ... Fixed optical member excavation, 19e ... Servo motor drive part, 21 ... Correction ring objective lens, 21a ... Fixed optics Member, 21b ... Fixed optical member, 21c ... Movable optical member, 21d ... Fixed optical member excavator, 21e ... Fixed optical member excavator, 21f ... Movable optical member excavator, 21g ... Adjusting ring, 21h ... Positive ring objective lens cover, 21i ... inclined portion, 21j ... memory, 30 ... system, 31 ... computing unit, 32 ... control unit, 33 ... memory, 34 ... display unit, 35 ... instruction unit.

Claims (8)

A light source that emits a laser beam;
A two-dimensional scanning mechanism for scanning the sample by deflecting the laser beam emitted from the light source;
A plurality of objective lenses for imaging the laser beam deflected by the two-dimensional scanning mechanism on the sample;
A beam splitter that is disposed between the light source and the two-dimensional scanning mechanism, transmits the laser beam emitted from the light source, and reflects reflected light reflected from the sample;
A light receiving unit for receiving the reflected light reflected by the beam splitter;
A calculation unit that calculates height information of the sample based on the intensity of the reflected light received by the light receiving unit;
A confocal laser microscope comprising:
A beam diameter changing unit that is arranged between the beam splitter and the two-dimensional scanning mechanism and changes the diameter of the laser beam that passes through the beam splitter in correspondence with the objective lens arranged on the optical path;
A confocal laser microscope characterized by comprising: An objective lens placement section that holds the plurality of objective lenses and places any one of the plurality of objective lenses on the optical path;
When the objective lens placement section places any one of the plurality of objective lenses on the optical path, the beam diameter changing section has the laser beam diameter placed on the optical path. The confocal laser microscope according to claim 1, wherein the confocal laser microscope is changed based on a diameter of a pupil of the objective lens.   The confocal laser microscope according to claim 2, wherein the objective lens placement unit is a revolver. The beam diameter changing part is
A plurality of beam expanders each having a different magnification and enlarging the diameter of the laser beam passing through the beam splitter;
A beam which holds the beam expander and which arranges the beam expander on the optical path based on the diameter of the pupil of the objective lens which is arranged on the optical path from the beam expander. An enlarger placement section;
The confocal laser microscope according to claim 1, wherein the confocal laser microscope is provided. The beam diameter changing part is
A plurality of optical members that change the diameter of the laser beam that passes through the beam splitter based on the diameter of the pupil of the objective lens disposed on the optical path, and an optical member adjustment unit that adjusts the relative distance between the optical members And a beam diameter variable portion consisting of:
The confocal laser microscope according to claim 1, wherein the confocal laser microscope is provided.   The confocal laser microscope according to claim 5, wherein the beam diameter varying unit adjusts a relative distance between the optical members by the optical member adjusting unit, thereby making the diameter of the laser beam variable. .   The confocal laser microscope according to claim 4, wherein the beam expander arrangement unit is a revolver. The objective lens is
A plurality of optical members;
An adjustment unit for adjusting a relative distance between the optical members;
The confocal laser microscope according to claim 1, further comprising:

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