Micro-Raman spectrometer

Abstract

To provide a microscope Raman device with which it is possible to shield laser light from one of a first and a second laser light source without having to turn one of the first and second light sources off, and to reduce a device size while enabling fine adjustment of laser light intensity.SOLUTION: A microscope Raman device comprises a first laser light source, a second laser light source, a first holder, a second holder, a first ND filter, and a second ND filter. The first and second laser light sources generate first laser light in a first wavelength and second laser light in a second wavelength, respectively. The second wavelength is different from the first wavelength. The first laser light and second laser light proceed along a second direction that is orthogonal to a first direction, in a state of being spaced from each other in the first direction. The first and second holders are arranged one on top of another in the second direction.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a microscopic Raman apparatus.

Background Art

[0002] For example, Japanese Patent Application Laid-Open No. 10-90064 (Patent Document 1) describes a microscopic Raman apparatus. The microscopic Raman apparatus described in Patent Document 1 includes an excitation laser, a spectroscope, and a detector. In the microscopic Raman apparatus described in Patent Document 1, when laser light from the excitation laser is irradiated onto a sample, Raman scattered light is generated from the sample. This Raman scattered light is dispersed in the spectroscope, and the intensity distribution of the dispersed Raman scattered light is detected by the detector.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A microscopic Raman apparatus may have a plurality of laser light sources (referred to as a first laser light source and a second laser light source) as excitation lasers. When the microscopic Raman apparatus has the first laser light source and the second laser light source, it is necessary to block the laser light from one of the first laser light source and the second laser light source from irradiating the sample using a shutter or turn off one of the first laser light source and the second laser light source.

[0005] When using a shutter to block the laser light from one of the first laser light source and the second laser light source, the microscopic Raman apparatus becomes large-sized. When turning off one of the first laser light source and the second laser light source, it takes time for the output to stabilize when turning on again the first laser light source and the second laser light source that was turned off.

[0006] Furthermore, in a micro-Raman microscope, it is necessary to finely adjust the intensity of the laser light irradiated onto the sample. This requires a large number of ND filters, which makes the micro-Raman microscope large.

[0007] The micro-Raman apparatus of this disclosure has been made in view of the above points. More specifically, it provides a micro-Raman apparatus that can shield the laser light from one of the first and second laser sources without turning off one of the first and second laser sources, and that can finely adjust the intensity of the laser light while miniaturizing the apparatus. [Means for solving the problem]

[0008] The micro-Raman apparatus of this disclosure comprises a first laser light source, a second laser light source, a first holder, a second holder, a first ND filter, and a second ND filter. The first and second laser light sources generate a first laser beam of a first wavelength and a second laser beam of a second wavelength, respectively. The second wavelength is different from the first wavelength. The first and second laser beams travel along a second direction perpendicular to the first direction, spaced apart from each other in the first direction. The first and second holders are arranged in a superposition in the second direction. The first holder is rotatable about a first axis of rotation parallel to the second direction. The second holder is rotatable about a second axis of rotation parallel to the second direction. The first holder has a first through hole, a second through hole, a third through hole, and a fourth through hole that penetrate the first holder in the second direction. The first and second through holes, when viewed along the second direction, lie on an arc centered on the first rotation axis with a radius equal to the distance between the first rotation axis and the first laser beam. The third and fourth through holes, when viewed along the second direction, lie on an arc centered on the first rotation axis with a radius equal to the distance between the first rotation axis and the second laser beam. The distance between the second and fourth through holes is smaller than the distance between the second and third through holes. When the first holder is rotated around the first rotation axis so that either the first or second through hole coincides with the first laser beam, both the third and fourth through holes are offset from the second laser beam. When the first holder is rotated around the first rotation axis so that either the third or fourth through hole coincides with the second laser beam, both the first and second through holes are offset from the first laser beam. The second holder has a fifth through-hole, a sixth through-hole, a seventh through-hole, and an eighth through-hole formed therein, penetrating the second holder in the second direction. The fifth and sixth through-holes, when viewed along the second direction, lie on an arc centered on the second rotation axis with a radius equal to the distance between the second rotation axis and the first laser beam. The seventh and eighth through-holes, when viewed along the second direction, lie on an arc centered on the second rotation axis with a radius equal to the distance between the second rotation axis and the second laser beam. The distance between the sixth and eighth through-holes is smaller than the distance between the sixth and seventh through-holes.When the second holder is rotated around the second rotation axis so that either the fifth through-hole or the sixth through-hole overlaps with the first laser beam, both the seventh through-hole and the eighth through-hole are offset from the second laser beam. When the second holder is rotated around the second rotation axis so that either the seventh through-hole or the eighth through-hole overlaps with the second laser beam, both the fifth through-hole and the sixth through-hole are offset from the first laser beam. The first ND filter is positioned on the first holder so as to straddle the second through-hole and the fourth through-hole. The second ND filter is positioned on the second holder so as to straddle the sixth through-hole and the eighth through-hole. [Effects of the Invention]

[0009] The micro-Raman apparatus of this disclosure makes it possible to block the laser light from one of the first and second laser sources without turning off one of the first and second laser sources, and also allows for fine adjustment of the laser light intensity while miniaturizing the apparatus. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram of the micro-Raman spectrometer 100. [Figure 2] This is a schematic side view of the light source adjustment unit 20 of the micro-Raman spectrometer 100. [Figure 3] This is a plan view of the first holder 24 of the micro-Raman spectrometer 100, as seen along the second direction DR2. [Figure 4] This is a plan view of the second holder 25 of the micro-Raman spectrometer 100, as seen along the second direction DR2. [Figure 5] This is a plan view of the first holder 24 of the micro-Raman apparatus 100, which is a modified example viewed along the second direction. [Figure 6] This is a plan view of the second holder 25 of the micro-Raman apparatus 100, which is a modified example viewed along the second direction. [Figure 7] This is a schematic diagram of the 200 micro-Raman spectrometer. [Figure 8]It is a plan view of a first holder 24 of a microscopic Raman apparatus 200 as seen along a second direction DR2. [Figure 9] It is a plan view of a second holder 25 of a microscopic Raman apparatus 200 as seen along a second direction DR2.

Mode for Carrying Out the Invention

[0011] Details of embodiments of the present disclosure will be described while referring to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and duplicate explanations will not be repeated.

[0012] (First Embodiment) A microscopic Raman apparatus according to the first embodiment will be described. The microscopic Raman apparatus according to the first embodiment is referred to as a microscopic Raman apparatus 100.

[0013] <Configuration of Microscopic Raman Apparatus 100> The configuration of the microscopic Raman apparatus 100 will be described below.

[0014] FIG. 1 is a schematic diagram of a microscopic Raman apparatus 100. As shown in FIG. 1, the microscopic Raman apparatus 100 includes a first laser light source 11, a second laser light source 12, a light source adjustment unit 20, a long-pass filter 41, a long-pass filter 42, a dichroic mirror 43, a dichroic mirror 44, a mirror 45, an objective lens 46, and a Raman spectroscope 50.

[0015] The first laser light source 11 generates a first laser beam L1. The second laser light source 12 generates a second laser beam L2. The light source adjustment unit 20 allows either the first laser beam L1 or the second laser beam L2 to pass through. When passing through the light source adjustment unit 20, the intensity of either the first laser beam L1 or the second laser beam L2 may be adjusted. Details of the light source adjustment unit 20 will be described later.

[0016] The first laser beam L1 that has passed through the light source adjuster 20 is reflected by the long-pass filter 41 and passes through the dichroic mirror 43. The first laser beam L1 that has passed through the dichroic mirror 43 is reflected by the mirror 45 and passes through the objective lens 46. As a result, the first laser beam L1 irradiates the sample S. When the first laser beam is irradiated, the first Raman beam L3 is generated from the sample S.

[0017] The first Raman beam L3 generated in the sample S passes through the objective lens 46 and is reflected by the mirror 45. The first Raman beam L3 reflected by the mirror 45 sequentially passes through the dichroic mirror 43 and the long-pass filter 41. The first Raman beam L3 that has passed through the long-pass filter 41 enters the Raman spectrometer 50. As a result, Raman measurement using the first laser beam L1 is performed.

[0018] The second laser beam L2 that has passed through the light source adjuster 20 is reflected by the long-pass filter 42 and passes through the dichroic mirror 44. The second laser beam L2 that has passed through the dichroic mirror 44 is reflected by the mirror 45 and passes through the objective lens 46. As a result, the second laser beam L2 irradiates the sample S. When the second laser beam is irradiated, the second Raman beam L4 is generated from the sample S.

[0019] The second Raman beam L4 generated in the sample S passes through the objective lens 46 and is reflected by the mirror 45. The second Raman beam L4 reflected by the mirror 45 sequentially passes through the dichroic mirror 44 and the long-pass filter 42. The second Raman beam L4 that has passed through the long-pass filter 42 enters the Raman spectrometer 50. As a result, Raman measurement using the second laser beam L2 is performed.

[0020] Figure 2 is a schematic side view of the light source adjustment unit 20 of the micro-Raman spectrometer 100. As shown in Figure 2, the light source adjustment unit 20 includes a base 21, a first axis member 22, a second axis member 23, a first holder 24, a second holder 25, an ND filter 26, and an ND filter 27.

[0021] The first laser light source 11 and the second laser light source 12 are positioned on the base 21 with a gap between them in the first direction DR1. The first laser beam L1 generated by the first laser light source 11 and the second laser beam L2 generated by the second laser light source 12 travel along the second direction DR2, which is perpendicular to the first direction DR1. That is, the first laser beam L1 and the second laser beam L2 travel along the second direction DR2 while being spaced apart in the first direction DR1.

[0022] The first shaft member 22 is attached to the base 21. The first shaft member 22 extends along the second direction DR2. The second shaft member 23 is attached to the base 21. The second shaft member 23 extends along the second direction DR2.

[0023] The first holder 24 is mounted on the first shaft member 22 so as to be rotatable around the first rotation axis A1. The first rotation axis A1 is parallel to the second direction DR2. The second holder 25 is mounted on the second shaft member 23 so as to be rotatable around the second rotation axis A2. The second rotation axis A2 is parallel to the second direction DR2. The distance between the first rotation axis A1 and the first laser beam L1 is denoted as distance DIS1. The distance between the first rotation axis A1 and the second laser beam L2 is denoted as distance DIS2. The distance between the second rotation axis A2 and the first laser beam L1 is denoted as distance DIS3. The distance between the second rotation axis A2 and the second laser beam L2 is denoted as distance DIS4. Distance DIS2 is greater than distance DIS1. Distance DIS3 is greater than distance DIS4.

[0024] The first holder 24 and the second holder 25 are made of a material that does not allow the first laser beam L1 and the second laser beam L2 to pass through. For example, the first holder 24 and the second holder 25 are made of a metallic material.

[0025] Figure 3 is a plan view of the first holder 24 of the micro-Raman spectrometer 100 as seen along the second direction DR2. As shown in Figure 3, the planar shape of the first holder 24 is, for example, semicircular. However, the planar shape of the first holder 24 is not limited to this. The first holder 24 has through holes 24a, 24b, 24c, and 24d. Through holes 24a, 24b, 24c, and 24d penetrate the first holder 24 along the second direction DR2.

[0026] When viewed along the second direction DR2, through holes 24a and 24b are located on the first arc. The first arc is centered on the first axis of rotation A1 and has a radius equal to the distance DIS1. When viewed along the second direction DR2, through holes 24c and 24d are located on the second arc. The second arc is centered on the first axis of rotation A1 and has a radius equal to the distance DIS2. The distance between through hole 24b and through hole 24d is less than or equal to the distance between through hole 24b and through hole 24c.

[0027] The through holes 24c and 24d are offset from the second laser beam L2 when the first holder 24 is rotated around the first rotation axis A1 so that the first laser beam L1 coincides with either the through hole 24a or the through hole 24b. The through holes 24a and 24b are offset from the first laser beam L1 when the first holder 24 is rotated around the first rotation axis A1 so that the second laser beam L2 coincides with either the through hole 24c or the through hole 24d. In other words, when viewed along the second direction DR2, the through holes 24a and 24b are not on the imaginary straight line connecting the through hole 24c and the first rotation axis A1, nor are they on the imaginary straight line connecting the through hole 24d and the first rotation axis A1.

[0028] To put this from another perspective, when the first holder 24 is rotated around the first rotation axis A1 so that the first laser beam L1 coincides with either the through hole 24a or the through hole 24b, the second laser beam L2 is blocked by the first holder 24, and when the first holder 24 is rotated around the first rotation axis A1 so that the second laser beam L2 coincides with either the through hole 24c or the through hole 24d, the first laser beam L1 is blocked by the first holder 24.

[0029] Figure 4 is a plan view of the second holder 25 of the micro-Raman spectrometer 100 as seen along the second direction DR2. As shown in Figure 4, the planar shape of the second holder 25 is, for example, semicircular. However, the planar shape of the second holder 25 is not limited to this. The second holder 25 has through holes 25a, 25b, 25c, and 25d. Through holes 25a, 25b, 25c, and 25d penetrate the second holder 25 along the second direction DR2.

[0030] When viewed along the second direction DR2, through holes 25a and 25b are located on the third arc. The third arc is centered on the second axis of rotation A2 and has a radius equal to the distance DIS3. When viewed along the second direction DR2, through holes 25c and 25d are located on the fourth arc. The fourth arc is centered on the second axis of rotation A2 and has a radius equal to the distance DIS4. The distance between through hole 25b and through hole 25d is less than or equal to the distance between through hole 25b and through hole 25c.

[0031] The through holes 25c and 25d are offset from the second laser beam L2 when the second holder 25 is rotated around the second rotation axis A2 so that the first laser beam L1 coincides with either the through hole 25a or the through hole 25b. The through holes 25a and 25b are offset from the first laser beam L1 when the second holder 25 is rotated around the second rotation axis A2 so that the second laser beam L2 coincides with either the through hole 25c or the through hole 25d. In other words, when viewed along the second direction DR2, the through holes 25c and 25d are not on the imaginary straight line connecting the through hole 25a and the second rotation axis A2, nor are they on the imaginary straight line connecting the through hole 25b and the second rotation axis A2.

[0032] To put this from another perspective, when the second holder 25 is rotated around the second rotation axis A2 so that the first laser beam L1 coincides with either the through hole 25a or the through hole 25b, the second laser beam L2 is blocked by the second holder 25, and when the second holder 25 is rotated around the second rotation axis A2 so that the second laser beam L2 coincides with either the through hole 25c or the through hole 25d, the first laser beam L1 is blocked by the second holder 25.

[0033] As shown in Figure 3, the ND filter 26 is positioned on the first holder 24 so as to straddle the through holes 24b and 24d. As shown in Figure 4, the ND filter 27 is positioned on the second holder 25 so as to straddle the through holes 25b and 25d. The OD value of the ND filter 26 is preferably different from the OD value of the ND filter 27. An ND (Neutral Density) filter is an optical filter that reduces the intensity of light passing through it. The OD (Optical Density) value is a value that indicates the light transmittance through the ND filter. When the OD value is X, the value obtained by dividing the intensity of light after passing through the ND filter by the intensity of light before passing through the ND filter is 1 × 10⁻¹⁰. -X This is the result.

[0034] <Effects of the Micro-Raman Spectrometer 100> In the micro-Raman spectrometer 100, if the first holder 24 is rotated around the first rotation axis A1 so that the through hole 24a or through hole 24b aligns with the first laser beam L1, and the second holder 25 is rotated around the second rotation axis A2 so that the through hole 25a or through hole 25b aligns with the first laser beam L1, the through holes 24c and 24d will be offset from the second laser beam L2, and the second laser beam L2 will be blocked by the first holder 24.

[0035] Similarly, in the micro-Raman apparatus 100, by rotating the first holder 24 around the first rotation axis A1 so that the through hole 24c or through hole 24d overlaps with the second laser beam L2, and rotating the second holder 25 around the second rotation axis A2 so that the through hole 25c or through hole 25d overlaps with the second laser beam L2, the through holes 24a and 24b are offset from the first laser beam L1, and the first laser beam L1 is blocked by the first holder 24. Thus, in the micro-Raman apparatus 100, it is unnecessary to turn off one of the first laser light source 11 and the second laser light source 12, and to provide a shutter, in order to selectively pass the first laser beam L1 and the second laser beam L2 through the light source adjustment unit 20.

[0036] The first laser beam L1 passes through through holes 24a and 25a in sequence in a first pattern, through holes 24b and 25a in a second pattern, through holes 24b and 25a in a third pattern, and through holes 24b and 25b in a fourth pattern. In the first pattern, the first laser beam L1 passes through the light source adjustment unit 20 without any intensity adjustment. In the second pattern, the first laser beam L1 passes through the light source adjustment unit 20 with intensity adjustment performed only by the ND filter 26. In the third pattern, the first laser beam L1 passes through the light source adjustment unit 20 with intensity adjustment performed only by the ND filter 27. In the fourth pattern, the first laser beam L1 passes through the light source adjustment unit 20 with intensity adjustment performed by both the ND filter 26 and ND filter 27. In other words, the micro-Raman spectrometer 100 allows for four patterns of intensity adjustment for the first laser beam L1 using the light source adjustment unit 20.

[0037] Similarly, in the micro-Raman spectrometer 100, the light source adjustment unit 20 allows for four patterns of intensity adjustment for the second laser beam L2. In this way, the micro-Raman spectrometer 100 allows for fine intensity adjustment of more patterns than the number of ND filters (2) for both the first laser beam L1 and the second laser beam L2, while also enabling miniaturization of the micro-Raman spectrometer 100.

[0038] <Variation> Figure 5 is a plan view of the first holder 24 of a modified micro-Raman apparatus 100 viewed along the second direction. As shown in Figure 5, the first holder 24 may further have through holes 24e and 24f formed therein. The through hole 24e is on the first arc, and the through hole 24f is on the second arc. When the first holder 24 is rotated around the first rotation axis A1 such that the through hole 24e coincides with the first laser beam L1, none of the through holes 24b, 24d, and 24f coincide with the second laser beam L2. When the first holder 24 is rotated around the first rotation axis A1 such that the through hole 24f coincides with the second laser beam L2, none of the through holes 24a, 24c, and 24e coincide with the first laser beam L1.

[0039] In this example, the distance between through-hole 24b and through-hole 24d is less than or equal to the distance between through-hole 24b and through-hole 24c and the distance between through-hole 24b and through-hole 24f, and the distance between through-hole 24e and through-hole 24f is less than or equal to the distance between through-hole 24e and through-hole 24c and the distance between through-hole 24e and through-hole 24d.

[0040] Figure 6 is a plan view of the second holder 25 of a micro-Raman apparatus 100 relating to a modified example viewed along the second direction. As shown in Figure 6, the second holder 25 may further have through holes 25e and 25f formed therein. The through hole 25e is on the third arc, and the through hole 25f is on the fourth arc. When the second holder 25 is rotated around the second rotation axis A2 such that the through hole 25e coincides with the first laser beam L1, none of the through holes 25b, 25d, and 25f coincide with the second laser beam L2. When the second holder 25 is rotated around the second rotation axis A2 such that the through hole 25f coincides with the second laser beam L2, none of the through holes 25a, 25c, and 25e coincide with the first laser beam L1.

[0041] In this example, the distance between through-hole 25b and through-hole 25d is less than or equal to the distance between through-hole 25b and through-hole 25c and the distance between through-hole 25b and through-hole 25f, and the distance between through-hole 25e and through-hole 25f is less than or equal to the distance between through-hole 25e and through-hole 25c and the distance between through-hole 25e and through-hole 25d.

[0042] The light source adjustment unit 20 may further include an ND filter 28 and an ND filter 29. The ND filter 28 is positioned on the first holder 24 so as to straddle the through holes 24e and 24f. The ND filter 29 is positioned on the second holder 25 so as to straddle the through holes 25e and 25f. The OD value of the ND filter 28 is preferably different from the OD value of the ND filter 26. The OD value of the ND filter 29 is preferably different from the OD value of the ND filter 27 and also different from the OD value of the ND filter 28.

[0043] It is preferable that the OD value of ND filter 26 is different from the sum of the OD values ​​of ND filter 27 and ND filter 28 or ND filter 29. It is preferable that the OD value of ND filter 27 is different from the sum of the OD values ​​of ND filter 26 and ND filter 28 or ND filter 29. It is preferable that the OD value of ND filter 28 is different from the sum of the OD values ​​of ND filter 26 or ND filter 27 and ND filter 29. It is preferable that the OD value of ND filter 29 is different from the sum of the OD values ​​of ND filter 26 or ND filter 27 and ND filter 28.

[0044] In this example, the intensity of the first laser beam L1 can be adjusted to nine patterns (a pattern with no intensity adjustment, a pattern with intensity adjustment by ND filter 26 only, a pattern with intensity adjustment by ND filter 27 only, a pattern with intensity adjustment by ND filter 28 only, a pattern with intensity adjustment by ND filter 29 only, a pattern with intensity adjustment by ND filter 26 and ND filter 27, a pattern with intensity adjustment by ND filter 26 and ND filter 29, a pattern with intensity adjustment by ND filter 28 and ND filter 27, and a pattern with intensity adjustment by ND filter 28 and ND filter 29), and similarly, the pattern of the second laser beam L2 can be adjusted to nine patterns.

[0045] As described above, in the micro-Raman spectrometer 100, the number of through holes on the first arc (referred to as the first through holes), the number of through holes on the second arc (referred to as the second through holes), the number of through holes on the third arc (referred to as the third through holes), and the number of through holes on the fourth arc (referred to as the fourth through holes) are not particularly limited. If the number of first through holes, second through holes, third through holes, and fourth through holes is k (where k is a natural number greater than or equal to 2), then the number of ND filters placed on the first holder 24 (referred to as the first ND filter) and the number of ND filters placed on the second holder 25 (referred to as the second ND filter) are (k-1).

[0046] When the first holder 24 is rotated around the first rotation axis A1 such that one of the multiple first through holes coincides with the first laser beam L1, all of the multiple second through holes are offset from the second laser beam L2. When the first holder 24 is rotated around the first rotation axis A1 such that one of the multiple second through holes coincides with the second laser beam L2, all of the multiple first through holes are offset from the first laser beam L1. When the second holder 25 is rotated around the second rotation axis A2 such that one of the multiple third through holes coincides with the first laser beam L1, all of the multiple fourth through holes are offset from the second laser beam L2. When the second holder 25 is rotated around the second rotation axis A2 such that one of the multiple fourth through holes coincides with the second laser beam L2, all of the multiple third through holes are offset from the first laser beam L1.

[0047] Each of the multiple first ND filters is positioned on the first holder 24 so as to straddle one first through-hole and one second through-hole located closest to the first through-hole, and each of the multiple second ND filters is positioned on the second holder 25 so as to straddle one third through-hole and one fourth through-hole located closest to the third through-hole.

[0048] (Second Embodiment) A micro-Raman apparatus according to the second embodiment will be described. The micro-Raman apparatus according to the second embodiment will be referred to as the micro-Raman apparatus 200. Here, we will mainly explain the differences from the micro-Raman apparatus 100, and will avoid repeating redundant explanations.

[0049] <Configuration of Micro-Raman Spectrometer 200> The configuration of the micro-Raman spectrometer 200 is described below.

[0050] Figure 7 is a schematic diagram of the micro-Raman spectrometer 200. As shown in Figure 7, the micro-Raman spectrometer 200 includes a first laser light source 11, a second laser light source 12, a light source adjustment unit 20, a long-pass filter 41, a long-pass filter 42, a dichroic mirror 43, a dichroic mirror 44, a mirror 45, an objective lens 46, and a Raman spectrometer 50. In this respect, the configuration of the micro-Raman spectrometer 200 is the same as that of the micro-Raman spectrometer 100.

[0051] Figure 8 is a plan view of the first holder 24 of the micro-Raman spectrometer 200 as viewed along the second direction DR2. As shown in Figure 8, the micro-Raman spectrometer 200 has through holes 24g and 24h further formed in the first holder 24. Through hole 24g is on the first arc, and through hole 24h is on the second arc. Through holes 24g and 24h penetrate the first holder 24 along the second direction DR2. When the first holder 24 is rotated around the first rotation axis A1 such that through hole 24g coincides with the first laser beam L1, through hole 24h coincides with the second laser beam L2. That is, when viewed along the second direction DR2, through hole 24g, through hole 24h, and the first rotation axis A1 lie on the same virtual straight line.

[0052] Figure 9 is a plan view of the second holder 25 of the micro-Raman spectrometer 200 as viewed along the second direction DR2. As shown in Figure 9, the micro-Raman spectrometer 200 has through holes 25g and 25h further formed in the second holder 25. Through hole 25g is on the third arc, and through hole 25h is on the fourth arc. Through holes 25g and 25h penetrate the second holder 25 along the second direction DR2. When the second holder 25 is rotated around the second rotation axis A2 such that through hole 25g coincides with the first laser beam L1, through hole 25h coincides with the second laser beam L2. That is, when viewed along the second direction DR2, through hole 25g, through hole 25h, and the second rotation axis A2 lie on the same virtual straight line.

[0053] In the micro-Raman spectrometer 200, the light source adjustment unit 20 further includes an ND filter 30 and an ND filter 31. The ND filter 30 is positioned on the first holder 24 so as to straddle the through holes 24g and 24h. The ND filter 31 is positioned on the second holder 25 so as to straddle the through holes 25g and 25h. The OD value of the ND filter 30 is preferably different from the OD value of the ND filter 26. The OD value of the ND filter 31 is preferably different from the OD value of the ND filter 27 and also different from the OD value of the ND filter 30.

[0054] It is preferable that the OD value of ND filter 26 is different from the sum of the OD value of ND filter 27 and the OD value of ND filter 30 or ND filter 31. It is preferable that the OD value of ND filter 27 is different from the sum of the OD value of ND filter 26 and the OD value of ND filter 30 or ND filter 31. It is preferable that the OD value of ND filter 30 is different from the sum of the OD value of ND filter 26 or ND filter 27 and ND filter 31. It is preferable that the OD value of ND filter 31 is different from the sum of the OD value of ND filter 26 or ND filter 27 and ND filter 30. In these respects, the configuration of the micro-Raman spectrometer 200 is different from the configuration of the micro-Raman spectrometer 100.

[0055] <Effects of the Micro-Raman Spectrometer 200> The effects of the 200 micro-Raman spectrometer are explained below.

[0056] In the micro-Raman spectrometer 200, the intensity of the first laser beam L1 can be adjusted to eight patterns (a pattern with no intensity adjustment, a pattern with intensity adjustment by ND filter 26 only, a pattern with intensity adjustment by ND filter 27 only, a pattern with intensity adjustment by ND filter 30 only, a pattern with intensity adjustment by ND filter 31 only, a pattern with intensity adjustment by ND filter 26 and ND filter 27, a pattern with intensity adjustment by ND filter 26 and ND filter 30, and a pattern with intensity adjustment by ND filter 30 and ND filter 27), and similarly, the pattern of the second laser beam L2 can be adjusted to eight patterns.

[0057] <Variation> In the micro-Raman spectrometer 200, the number of through holes on the first arc (referred to as the first through holes), the number of through holes on the second arc (referred to as the second through holes), the number of through holes on the third arc (referred to as the third through holes), and the number of through holes on the fourth arc (referred to as the fourth through holes) are not particularly limited. If the number of first through holes, second through holes, third through holes, and fourth through holes is k (where k is a natural number greater than or equal to 2), then the number of ND filters placed on the first holder 24 (referred to as the first ND filter) and the number of ND filters placed on the second holder 25 (referred to as the second ND filter) are (k-1).

[0058] One of the multiple first through holes is designated as the fifth through hole. One of the multiple second through holes is designated as the sixth through hole. One of the multiple third through holes is designated as the seventh through hole. One of the multiple fourth through holes is designated as the eighth through hole. When the first holder 24 is rotated around the first rotation axis A1 so that the fifth through hole coincides with the first laser beam L1, the sixth through hole coincides with the second laser beam L2. When the second holder 25 is rotated around the second rotation axis A2 so that the seventh through hole coincides with the first laser beam L1, the eighth through hole coincides with the second laser beam L2.

[0059] When the first holder 24 is rotated around the first rotation axis A1 such that any of the multiple first through holes other than the fifth through hole aligns with the first laser beam L1, all of the multiple second through holes are offset from the second laser beam L2, and when the first holder 24 is rotated around the first rotation axis A1 such that any of the multiple second through holes other than the sixth through hole aligns with the second laser beam L2, all of the multiple first through holes are offset from the second laser beam L2. 1 Laser light L 1 They are misaligned. When the second holder 25 is rotated around the second rotation axis A2 such that any of the multiple third through holes other than the seventh through hole overlaps with the first laser beam L1, all of the multiple fourth through holes are misaligned with the second laser beam L2. When the second holder 25 is rotated around the second rotation axis A2 such that any of the multiple fourth through holes other than the eighth through hole overlaps with the second laser beam L2, all of the multiple third through holes are misaligned with the first laser beam L1.

[0060] One of the multiple first ND filters is designated as the third ND filter. The third ND filter is positioned on the first holder 24 so as to straddle the fifth and sixth through holes. One of the multiple second ND filters is designated as the fourth ND filter. The fourth ND filter is positioned on the second holder 25 so as to straddle the seventh and eighth through holes. Each of the multiple first ND filters other than the third ND filter is positioned on the first holder 24 so as to straddle one first through hole other than the fifth through hole and a second through hole other than the sixth through hole which is closest to that first through hole. Each of the multiple second ND filters other than the fourth ND filter is positioned on the second holder 25 so as to straddle one third through hole other than the seventh through hole and a fourth through hole other than the eighth through hole which is closest to that third through hole.

[0061] (Note) The above embodiment includes the following configuration:

[0062] <Note 1> First laser light source, The second laser light source, First holder and, The second holder, First ND filter and, Equipped with a second ND filter, The first laser light source and the second laser light source each generate a first laser beam of a first wavelength and a second laser beam of a second wavelength, respectively. The second wavelength differs from the first wavelength, The first laser beam and the second laser beam travel along a second direction perpendicular to the first direction, while being spaced apart from each other in the first direction. The first holder and the second holder are arranged overlapping in the second direction. The first holder is rotatable about a first axis of rotation parallel to the second direction, The second holder is rotatable about a second axis of rotation parallel to the second direction, The first holder has a first through hole, a second through hole, a third through hole, and a fourth through hole formed therein, which penetrate the first holder in the second direction. The first through-hole and the second through-hole, when viewed along the second direction, lie on an arc centered on the first rotation axis with a radius equal to the distance between the first rotation axis and the first laser beam. The third and fourth through holes, when viewed along the second direction, lie on an arc centered on the first rotation axis with a radius equal to the distance between the first rotation axis and the second laser beam. The distance between the second through hole and the fourth through hole is smaller than the distance between the second through hole and the third through hole. When the first holder is rotated around the first rotation axis such that either the first through hole or the second through hole coincides with the first laser beam, both the third through hole and the fourth through hole are offset from the second laser beam. When the first holder is rotated around the first rotation axis such that either the third through hole or the fourth through hole overlaps with the second laser beam, both the first through hole and the second through hole are offset from the first laser beam. The second holder has a fifth through hole, a sixth through hole, a seventh through hole, and an eighth through hole formed therein, which penetrate the second holder in the second direction. The fifth through-hole and the sixth through-hole, when viewed along the second direction, lie on an arc centered on the second rotation axis with a radius equal to the distance between the second rotation axis and the first laser beam. The seventh and eighth through holes, when viewed along the second direction, lie on an arc centered on the second rotation axis with a radius equal to the distance between the second rotation axis and the second laser beam. The distance between the sixth through hole and the eighth through hole is smaller than the distance between the sixth through hole and the seventh through hole. When the second holder is rotated around the second rotation axis such that either the fifth through hole or the sixth through hole overlaps with the first laser beam, both the seventh through hole and the eighth through hole are offset from the second laser beam. When the second holder is rotated around the second rotation axis such that either the seventh through hole or the eighth through hole overlaps with the second laser beam, both the fifth through hole and the sixth through hole are offset from the first laser beam. The first ND filter is positioned on the first holder so as to straddle the second through hole and the fourth through hole, A micro-Raman spectrometer is provided in which the second ND filter is positioned on the second holder so as to straddle the sixth through-hole and the eighth through-hole.

[0063] <Note 2> The micro-Raman spectrometer described in Appendix 1, wherein the OD value of the second ND filter is different from the OD value of the first ND filter.

[0064] <Note 3> The 3rd ND filter and, It also features a 4th ND filter, The first holder is further formed with a ninth through hole and a tenth through hole that penetrate the first holder in the second direction. When the first holder is rotated around the first rotation axis such that the ninth through hole coincides with the first laser beam, the tenth through hole coincides with the second laser beam. The second holder is further formed with an eleventh through hole and a twelfth through hole that penetrate the second holder in the second direction. The second holder is positioned such that the 11th through hole overlaps with the first laser beam. 2 When rotated around the axis of rotation, the 12th through-hole overlaps with the second laser beam. The third ND filter is positioned on the first holder so as to straddle the ninth through hole and the tenth through hole, The micro-Raman apparatus according to Appendix 1 or Appendix 2, wherein the fourth ND filter is positioned on the second holder so as to straddle the eleventh through-hole and the twelfth through-hole.

[0065] <Note 4> The OD value of the third ND filter is different from the OD value of the first ND filter. The micro-Raman apparatus described in Appendix 3, wherein the OD value of the fourth ND filter is different from the OD value of the second ND filter and also different from the OD value of the third ND filter.

[0066] While embodiments of this disclosure have been described above, various modifications of these embodiments are possible. Furthermore, the scope of the present invention is not limited to the embodiments described above. The scope of the present invention is indicated by the claims and is intended to include all modifications within the meaning and scope equivalent to the claims. [Explanation of symbols]

[0067] A1 First rotation axis, A2 Second rotation axis, DIS1, DIS2, DIS3, DIS4 Distance, DR1 First direction, DR2 Second direction, L1 First laser beam, L2 Second laser beam, L3 First Raman beam, L4 Second Raman beam, S Sample, 100 Micro-Raman apparatus, 11 First laser light source, 12 Second laser light source, 20 Light source adjustment unit, 21 Base, 22 First axis member, 23 Second axis member, 24 First holder, 24a, 24b, 24c, 24d, 24e, 24f, 24g, 24h Through hole, 25 Second holder, 25a, 25b, 25c, 25d, 25e, 25f, 25g, 25h Through hole, 26, 27, 28, 29, 30, 31 ND filter, 41, 42 Long-pass filter, 43, 44 Dichroic mirror, 45 Mirror, 46 Objective lens, 50 Raman spectrometer, 200 Micro-Raman spectrometer.

Claims

1. First laser light source, The second laser light source, First holder and, The second holder and, First ND filter and, It is equipped with a second ND filter, The first laser light source and the second laser light source each generate a first laser beam of a first wavelength and a second laser beam of a second wavelength, respectively. The second wavelength differs from the first wavelength, The first laser beam and the second laser beam travel along a second direction perpendicular to the first direction, while being spaced apart from each other in the first direction. The first holder and the second holder are arranged in overlapping positions in the second direction. The first holder is rotatable about a first axis of rotation parallel to the second direction, The second holder is rotatable about a second axis of rotation parallel to the second direction, The first holder has a first through hole, a second through hole, a third through hole, and a fourth through hole formed therein, which penetrate the first holder in the second direction. The first through-hole and the second through-hole, when viewed along the second direction, lie on an arc centered on the first rotation axis with a radius equal to the distance between the first rotation axis and the first laser beam. The third and fourth through holes, when viewed along the second direction, lie on an arc centered on the first rotation axis with a radius equal to the distance between the first rotation axis and the second laser beam. The distance between the second through hole and the fourth through hole is smaller than the distance between the second through hole and the third through hole. When the first holder is rotated around the first rotation axis such that either the first through hole or the second through hole coincides with the first laser beam, both the third through hole and the fourth through hole are offset from the second laser beam. When the first holder is rotated around the first rotation axis such that either the third through hole or the fourth through hole coincides with the second laser beam, both the first through hole and the second through hole are offset from the first laser beam. The second holder has a fifth through hole, a sixth through hole, a seventh through hole, and an eighth through hole formed therein, which penetrate the second holder in the second direction. The fifth through-hole and the sixth through-hole, when viewed along the second direction, lie on an arc centered on the second rotation axis with a radius equal to the distance between the second rotation axis and the first laser beam. The seventh through-hole and the eighth through-hole are, when viewed along the second direction, on an arc centered on the second rotation axis with a radius equal to the distance between the second rotation axis and the second laser beam. The distance between the sixth through hole and the eighth through hole is smaller than the distance between the sixth through hole and the seventh through hole. When the second holder is rotated around the second rotation axis such that either the fifth through hole or the sixth through hole overlaps with the first laser beam, both the seventh through hole and the eighth through hole are offset from the second laser beam. When the second holder is rotated around the second rotation axis such that either the seventh through hole or the eighth through hole overlaps with the second laser beam, both the fifth through hole and the sixth through hole are offset from the first laser beam. The first ND filter is positioned on the first holder so as to straddle the second through hole and the fourth through hole, A micro-Raman spectrometer is provided in which the second ND filter is positioned on the second holder so as to straddle the sixth through-hole and the eighth through-hole.

2. The micro-Raman apparatus according to claim 1, wherein the OD value of the second ND filter is different from the OD value of the first ND filter.

3. The third ND filter, It is further equipped with a fourth ND filter, The first holder is further provided with a ninth through hole and a tenth through hole that penetrate the first holder in the second direction. When the first holder is rotated around the first rotation axis such that the ninth through hole coincides with the first laser beam, the tenth through hole coincides with the second laser beam. The second holder is further provided with an eleventh through hole and a twelfth through hole that penetrate the second holder in the second direction. When the second holder is rotated around the second rotation axis such that the 11th through hole coincides with the first laser beam, the 12th through hole coincides with the second laser beam. The third ND filter is positioned on the first holder so as to straddle the ninth through hole and the tenth through hole, The micro-Raman apparatus according to claim 1 or 2, wherein the fourth ND filter is positioned on the second holder so as to straddle the eleventh through-hole and the twelfth through-hole.

4. The OD value of the third ND filter is different from the OD value of the first ND filter. The micro-Raman apparatus according to claim 3, wherein the OD value of the fourth ND filter is different from the OD value of the second ND filter and also different from the OD value of the third ND filter.

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