Method for adjusting laser intensity and device for adjusting laser intensity

Abstract

The present invention relates to a laser intensity adjusting device (12) which adjusts the intensity of linearly polarized laser light, i.e. incident laser light, to a prescribed intensity and emits the laser light, and includes: an intensity changing optical element (polarizing beam splitter (123)) which is disposed on the optical path of the incident laser light, transmits a component of the polarization of the incident laser light in a prescribed transmission direction, thereby changing the intensity of the emitted laser light, and which is rotatable about the optical axis of the incident laser light in a range of at least 90° from a prescribed reference angle, so that the transmission direction is variable; and a polarization direction changing optical element (concave lens (121)) which is disposed on the optical path of the incident laser light further forward than the intensity changing optical element, changes the polarization direction of the incident laser light and emits the laser light, and which is variable in the changed direction.

Description

Technical Field

[0001] This invention relates to a method and apparatus for adjusting the intensity of a laser. Background Technology

[0002] Previously, matrix-assisted laser desorption / ionization (MALDI) has been used as one method for ionizing analytes in mass analysis. In MALDI, a sample prepared by mixing the analyte and a matrix is ​​irradiated with a laser for a short period, causing the analyte to vaporize and almost simultaneously ionizing the molecules constituting it. By mixing the matrix in this way and appropriately adjusting the laser intensity, molecular destruction during laser irradiation can be prevented, thus achieving ionization simultaneously.

[0003] Patent Document 1 describes an apparatus for adjusting the intensity of laser light irradiating a sample in the MALDI method. This laser intensity adjustment apparatus includes: a laser source emitting linearly polarized laser light; and an "energy adjustment component" that allows the laser light to pass through at different transmittances depending on the polarization direction of the transmitted laser light. Specifically, the "energy adjustment component" may be a polarizing beam splitter. The polarizing beam splitter allows the component of the incident linearly polarized light parallel to a predetermined direction (transmission direction) to pass through, and reflects the component orthogonal to it. In the laser intensity adjustment apparatus of Patent Document 1, the polarizing beam splitter is configured to rotate about the optical axis of the laser light emitted from the laser source. When the transmission direction is rotated about this optical axis, the intensity of the polarized light passing through the polarizing beam splitter changes in the following manner: it reaches a maximum value when the transmission direction is aligned with the polarization direction of the incident linearly polarized light, and then becomes 0 when the polarizing beam splitter is rotated 90°. Therefore, the polarizing beam splitter is configured so that the light passing through the polarizing beam splitter illuminates the sample. Based on this, the polarization direction of the laser emitted from the laser source is aligned with the transmission direction of the polarizing beam splitter as the reference angle. The polarizing beam splitter is rotated within a range of 90° from this reference angle, thereby allowing the intensity of the laser illuminating the sample to be adjusted within a range from a specified maximum value to 0.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Utility Model Registration No. 3217378 Summary of the Invention

[0007] The technical problem that the invention aims to solve

[0008] In the MALDI method, conventionally, a concave lens is placed immediately after the laser source in the optical path of the laser irradiating the sample to expand the laser beam, and a convex lens is placed immediately before the sample to focus the laser beam again. This suppresses the energy density between the concave and convex lenses, ensuring safety, and by using the convex lens for focusing, the laser can irradiate the sample with high energy density. However, in this invention, the inventors placed a polarizing beam splitter between the concave and convex lenses in the device, and rotated the transmission direction of the polarizing beam splitter within a 90° range from the reference angle. Simultaneously, the intensity of the laser irradiating the sample was measured, and it was found that the maximum value of the intensity did not reach the specified value, or the minimum value was not zero. This results in a narrowing range of laser intensity variation irradiating the sample, making proper ionization of the sample impossible.

[0009] Furthermore, if the range of adjustment for the intensity of the laser irradiating the sample can be intentionally narrowed, it is easy to fine-tune that intensity. However, in the device of Patent Document 1, it is not possible to make changes to narrow the adjustment range.

[0010] The technical problem to be solved by the present invention is to provide a method for adjusting the intensity range of a laser, and a laser intensity adjustment device using the method.

[0011] Solution to the above technical problems

[0012] The laser intensity adjustment method of the present invention, completed to solve the above-mentioned technical problems, is a method for adjusting the intensity of linearly polarized laser light, i.e., the incident laser, to a predetermined intensity for emission.

[0013] An intensity-changing optical element is configured, which changes the intensity of the emitted laser by allowing the polarized component of the incident laser in a predetermined transmission direction to pass through the optical path of the incident laser, and the optical element rotates about the optical axis of the incident laser within a range of at least 90° from a predetermined reference angle to make the transmission direction variable.

[0014] A polarization direction changing optical element is configured, which is positioned further forward than the intensity changing optical element in the optical path of the incident laser to change the polarization direction of the incident laser and emit it, and the direction of the change (the direction in which the polarization direction is changed) is variable.

[0015] The direction of the change is adjusted so that the polarization direction of the incident laser emitted from the polarization direction changing optical element is consistent with the transmission direction when the rotation angle of the intensity changing optical element is the reference angle.

[0016] The laser intensity adjustment device of the present invention is a device for adjusting the intensity of linearly polarized laser light, i.e., incident laser light, to a predetermined intensity for emission, and includes:

[0017] An intensity-changing optical element is disposed in the optical path of the incident laser, allowing the polarized component of the incident laser in a predetermined transmission direction to pass through, thereby changing the intensity of the emitted laser. The optical element rotates about the optical axis of the incident laser within a range of at least 90° from a predetermined reference angle, making the transmission direction variable.

[0018] A polarization direction changing optical element is disposed further forward than the intensity changing optical element in the optical path of the incident laser, changing the polarization direction of the incident laser and emitting it, and the direction of the change is variable.

[0019] Invention Effects

[0020] The inventors of this application have discovered that some optical elements, such as lenses, possess the characteristic of changing the polarization direction of incident laser light (without changing its intensity) and emitting it. Furthermore, by rotating such an optical element around the optical axis of the incident laser, the direction of polarization can be changed (without changing the intensity). In this specification, an optical element that changes the polarization direction of incident laser light and emits it, and where the direction of polarization is variable, is referred to as a polarization direction changing optical element. On the other hand, an intensity changing optical element changes the intensity of the emitted laser light by allowing the component of the polarized light whose direction has been changed by the polarization direction changing optical element to pass through, and where the transmission direction is variable. By combining the above-mentioned polarization direction changing optical element and intensity changing optical element, the polarization direction of the incident laser light is changed by the polarization direction changing optical element, thus enabling the adjustment range of the intensity of the emitted laser light during the period when the transmission direction of the intensity changing optical element is changed within a specified range, i.e., the range of laser intensity adjustment. Attached Figure Description

[0021] Figure 1 This is a schematic diagram illustrating an example of a MALDI ion source incorporating an embodiment of the laser intensity adjustment device of the present invention.

[0022] Figure 2 This is a graph showing the relationship between the rotation angle of the polarizing beam splitter and the intensity of the laser transmitted through the polarizing beam splitter when the polarization direction of the incident laser is consistent with the transmission direction of the polarizing beam splitter (intensity changing optical element) in the laser intensity adjustment device of this embodiment.

[0023] Figure 3 This diagram schematically illustrates the polarization direction of the laser incident on the polarizing beam splitter and the transmission direction of the polarizing beam splitter in the laser intensity adjustment device of this embodiment.

[0024] Figure 4 This is a graph showing the relationship between the rotation angle of the polarizing beam splitter and the intensity of the laser transmitted through the polarizing beam splitter when the polarization direction of the incident laser is offset by an angle θ0 from the transmission direction of the polarizing beam splitter in the laser intensity adjustment device of this embodiment.

[0025] Figure 5 This is a graph showing the relationship between the rotation angle of the polarizing beam splitter and the intensity of the laser transmitted through the polarizing beam splitter when the polarization direction of the incident laser is offset from the transmission direction of the polarizing beam splitter by an angle -θ0 in the laser intensity adjustment device of this embodiment.

[0026] Figure 6 This is a graph showing the relationship between the rotation angle of the concave lens and the energy of the laser transmitted through the polarizing beam splitter in the laser intensity adjustment device of this embodiment, obtained through experiments. Detailed Implementation

[0027] use Figures 1-6 The embodiments of the laser intensity adjustment method and apparatus of the present invention will be described.

[0028] Figure 1 This is a schematic diagram showing a MALDI ion source 10 including a laser intensity adjustment device 12 as an embodiment of the present invention. The MALDI ion source 10 includes: a laser source 11, a concave lens (polarization direction changing optical element) 121, a concave lens rotation mechanism 122, a reflector 13, a polarizing beam splitter (intensity changing optical element) 123, a polarizing beam splitter rotation mechanism 124, a convex lens 14, a sample chamber 15, and a camera 16. Of these components, the laser intensity adjustment device 12 is composed of the concave lens 121, the concave lens rotation mechanism 122, the polarizing beam splitter 123, and the polarizing beam splitter rotation mechanism 124.

[0029] The laser source 11 is a light source that oscillates linearly polarized laser light. In this embodiment, the laser source 11 uses an ultraviolet laser with an oscillation wavelength of 349 nm, but in this invention, the wavelength of the laser is not particularly limited.

[0030] The concave lens 121 is made of synthetic quartz, a material that readily transmits ultraviolet light, and is positioned in the optical path of the laser emitted from the laser source 11. The incident side of the concave lens 121 is concave, and the exit side is a convex surface with a smaller curvature than the incident side, giving it an overall concave shape. This shape allows the laser beam incident on the concave lens 121 to become parallel after beam dilation. The purpose of using the concave lens 121 is to suppress the energy density between the concave lens 121 and the convex lens 14 by dilating the laser beam, ensuring safety, and to irradiate the sample S with high energy density by focusing the light using the convex lens 14 as described below.

[0031] The original purpose of a concave lens 121 is to expand the diameter of a laser beam. However, the inventors of this application have discovered that the concave lens 121 also possesses the following characteristic: it changes the polarization direction when linearly polarized laser light passes through it, and the direction of the change changes by rotating about the optical axis of the incident laser. In other words, the concave lens 121 is equivalent to a polarization direction changing optical element.

[0032] The concave lens rotation mechanism 122 is based on the optical axis of the laser (in Figure 1 The device that rotates the concave lens 121 around a center (shown as a dashed line). The concave lens rotation mechanism 122 can rotate the concave lens 121 using power from an electric motor or the like, or it can be unpowered itself and rotatably hold the concave lens 121 so that it can be manually rotated. Furthermore, a brake can be provided on the concave lens rotation mechanism 122 to fix the concave lens 121 when it is not rotating.

[0033] Reflector 13 is positioned in the optical path of the laser light passing through concave lens 121, such that the angle of incidence towards the reflecting surface is 45°. Ultraviolet light of a specific wavelength band containing the laser light is reflected at a 90° angle, while light of wavelengths not included in this band passes through reflector 13. Visible light is not included in this band.

[0034] The polarizing beam splitter 123 is positioned in the optical path of the laser beam reflected by the reflector 13. When the polarization direction of the incident laser beam is aligned with the predetermined transmission direction, the laser beam is allowed to pass through. When the polarization direction is orthogonal to the transmission direction, the laser beam is completely reflected to a 90° angle. More generally, if the laser beam incident on the polarizing beam splitter 123 (intensity A)... max Let θ be the angle between the transmission direction and the polarization direction of the light beam, then the intensity of the laser beam passing through the polarizing beam splitter 123 becomes A. max cosθ (refer to Figure 2 In addition, the visible light captured by camera 16, described later, is not reflected but passes through polarizing beam splitter 123.

[0035] The polarizing beam splitter rotation mechanism 124 is a device that rotates the polarizing beam splitter 123 with the optical axis of the laser as the center. It can be configured such that the polarizing beam splitter 123 can be rotated by the power of an electric motor or the like, or it can be configured not to have its own power, but to hold the polarizing beam splitter 123 in a rotatable manner and to be rotated manually.

[0036] A shielding portion 1231 is provided around the polarizing beam splitter 123 to shield the laser light reflected by the polarizing beam splitter 123 in a 90° direction from being released to the outside.

[0037] A convex lens 14 is disposed in the optical path of the laser beam passing through the polarizer beam splitter 123 and is disposed on the wall of the sample chamber 15. The sample chamber 15 is disposed in the mass analysis apparatus performing the MALDI method, and a sample holding part 151 is disposed in the sample chamber 15 to hold the sample S, which is a mixture of the analyte and the matrix. The convex lens 14 is configured to focus the laser beam onto the sample S held in the sample holding part 151.

[0038] Camera 16 is positioned opposite convex lens 14, separated by polarizing beam splitter 123 and reflector 13. It captures images of the sample chamber 15 using visible light incident from the sample chamber 15 through polarizing beam splitter 123 and reflector 13. The purpose of camera 16 is to adjust the laser irradiation position and the sample position based on the captured images. This adjustment of the irradiation position and sample position is not directly related to the present invention, and therefore a detailed description is omitted.

[0039] Next, the operation of the MALDI ion source 10, which includes the laser intensity adjustment device 12 of this embodiment, and the laser intensity adjustment method of the present invention will be described.

[0040] First, the polarizing beam splitter 123 is rotated by the polarizing beam splitter rotation mechanism 124 to make the transmission direction 21 ( Figure 3 Oriented towards a specified reference angle. Here, the reference angle is typically defined as the angle such that the transmission direction 21 aligns with the polarization direction 221 when the polarization direction 221 of the laser emitted from the laser source 11 remains unchanged and is incident on the polarizing beam splitter 123. Assuming that the polarization direction 221 of the incident laser does not change when it is emitted from the laser source 11, the intensity of the laser passing through the polarizing beam splitter 123 depends on the rotation angle θ from the reference angle, which is A. max cosθ(A max (This is a constant). Therefore, the polarizing beam splitter 123 is rotated 90° from the reference angle ( Figure 2 The adjustment range of laser intensity 232 during the rotation range 231) is from the maximum value A. max The range up to the minimum value of 0.

[0041] However, in reality, the polarization direction of the laser emitted from the laser source 11 changes due to passing through the concave lens 121. Here, the angle formed by the polarization direction 221 when it remains unchanged and the polarization direction 222 after the change is defined as θ0. Figure 3 If the polarizing beam splitter 123 is rotated 90° from the reference angle in this state, the maximum intensity of the laser light passing through the polarizing beam splitter 123 during this period is only A. max cosθ0(<A max Thus, when the polarizing beam splitter 123 is rotated 90° from the reference angle, the intensity adjustment range 233 of the laser is from the maximum value A. max cosθ0(<A max The range up to the minimum value of 0. Figure 4 The intensity adjustment range 232 is narrower compared to the case where the polarization direction 221 does not change when emitted from the laser source 11.

[0042] Similarly, when the angle formed between the unchanged polarization direction 221 and the polarization direction 222 after the change from that polarization direction is -θ0 (the polarization direction shift is in the opposite direction of the example above), the maximum value of the laser intensity adjustment range 234 when the polarizer 123 is rotated 90° from the reference angle is A. max The minimum value is A max cos(90°-θ0)(>0)( Figure 5 In this case, the adjustment range 234 is also narrower than the intensity adjustment range 232 when the polarization direction 221 does not change when it is emitted from the laser source 11.

[0043] Therefore, by using the concave lens rotation mechanism 122 to rotate the concave lens 121, the polarization direction is changed so that the polarization direction of the laser light passing through the concave lens 121 is consistent with the transmission direction 21 of the polarizing beam splitter 123. Thus, when the polarizing beam splitter 123 is rotated 90° from the reference angle, the adjustment range of the laser intensity is from the maximum value A. max The range up to the minimum value of 0 is adjusted to its maximum size.

[0044] After setting the laser intensity adjustment range as described above, the polarizer beam splitter 123 is rotated within a range of 90° from the reference angle using the polarizer beam splitter rotation mechanism 124, thereby adjusting the intensity of the laser irradiating the sample S within the aforementioned adjustment range. This allows for the appropriate setting of the laser intensity irradiated when the sample S is ionized in the mass analysis apparatus.

[0045] To confirm that rotating the concave lens 121 around the optical axis of the laser changes the direction of the linearly polarized laser light passing through it, the following experiment was conducted: The concave lens 121 was rotated with the polarizing beam splitter 123 fixed, and the energy (corresponding to intensity) of the laser light passing through the polarizing beam splitter 123 was measured. The results of this experiment are shown below. Figure 6 In the graph, the horizontal axis represents the rotation angle φ of the concave lens 121 (different from the rotation angle θ of the polarizing beam splitter 123). Furthermore, any one rotation position is defined as the reference angle of φ (φ = 0°). For example... Figure 6 As shown, although the polarizing beam splitter 123 is fixed, the energy of the laser light passing through the polarizing beam splitter 123 changes as the rotation angle φ of the concave lens 121 changes. This indicates that the direction of the linearly polarized laser light passing through the concave lens 121 is changing. Based on this experimental result, it is believed that the rotation angle φ is approximately 90°. a At this point, the laser energy reaches its maximum, and the direction of the linearly polarized laser light passing through the concave lens 121 is consistent with the transmission direction of the polarizing beam splitter 123. Therefore, with this rotation angle φ a By fixing the concave lens 121 and rotating the polarizing beam splitter 123, the adjustment range of the laser energy (intensity) can be set to the maximum.

[0046] [Variation Example]

[0047] The present invention is not limited to the above embodiments. For example, in the above embodiments, the rotation angle of the concave lens 121 is adjusted to maximize the adjustment range of the laser intensity. However, in order to make fine-tuning of the intensity easier, the rotation angle can also be adjusted to intentionally narrow the adjustment range of the laser intensity.

[0048] In the above embodiments, a concave lens is used as a polarization direction-changing optical element, but the shape of the concave lens is not limited to the shape described above. Furthermore, a convex lens can be disposed in front of the intensity-changing optical element to replace the concave lens as a polarization direction-changing optical element. Moreover, optical elements other than lenses such as bandpass filters that allow only specific wavelengths of laser light to pass through also possess the characteristics of polarization direction-changing optical elements, and these optical elements can also be used in the present invention.

[0049] In the above embodiments, the polarizing beam splitter is used as an intensity-changing optical element. Alternatively, a polarizing plate or the like can also be used.

[0050] In the above embodiments, the example described is the case where the intensity of the laser irradiated to ionize the sample is adjusted in the mass analysis apparatus. However, the application of the present invention is not limited to this. For example, the present invention can also be applied to cases where laser is used for processing such as cutting or welding.

[0051] [plan]

[0052] Those skilled in the art will understand that the above exemplary embodiments are specific examples of the following schemes.

[0053] (Item 1)

[0054] The laser intensity adjustment method in item 1 is a method of adjusting the intensity of linearly polarized laser light, i.e., the incident laser, to a specified intensity for emission. Among these methods,

[0055] An intensity-changing optical element is configured, which changes the intensity of the emitted laser by allowing the polarized component of the incident laser in a predetermined transmission direction to pass through the optical path of the incident laser, and the optical element rotates about the optical axis of the incident laser within a range of at least 90° from a predetermined reference angle to make the transmission direction variable.

[0056] A polarization direction changing optical element is configured, which is positioned further forward than the intensity changing optical element in the optical path of the incident laser to change the polarization direction of the incident laser and emit it, and the direction of the change (the direction in which the polarization direction is changed) is variable.

[0057] The direction of the change is adjusted so that the polarization direction of the incident laser emitted from the polarization direction changing optical element is consistent with the transmission direction when the rotation angle of the intensity changing optical element is the reference angle.

[0058] (Item 4)

[0059] The laser intensity adjustment device in item 4 is a device that adjusts the intensity of linearly polarized laser light, i.e., the incident laser light, to a specified intensity for emission, and includes:

[0060] An intensity-changing optical element is disposed in the optical path of the incident laser, allowing the polarized component of the incident laser in a predetermined transmission direction to pass through, thereby changing the intensity of the emitted laser. The optical element rotates about the optical axis of the incident laser within a range of at least 90° from a predetermined reference angle, making the transmission direction variable.

[0061] A polarization direction changing optical element is disposed further forward than the intensity changing optical element in the optical path of the incident laser, changing the polarization direction of the incident laser and emitting it, and the direction of the change is variable.

[0062] According to the laser intensity adjustment method in item 1 and the laser intensity adjustment device in item 4, since the polarization direction of the incident laser is changed by the polarization direction changing optical element, the range of change of the intensity of the emitted laser during the period when the transmission direction of the intensity changing optical element is changed within a specified range can be changed, that is, the range of adjustment of the laser intensity.

[0063] At this point, by adjusting the direction of polarization change using the polarization direction-changing optical element, the polarized light emitted from the polarization direction-changing optical element and incident on the intensity-changing optical element is aligned with the transmission direction when the rotation angle of the intensity-changing optical element is a reference angle. Therefore, during the period when the intensity-changing optical element rotates 90° from the specified reference angle, the laser intensity changes from its maximum value to 0. Thus, the intensity adjustment range can be set to the maximum range achievable by the intensity-changing optical element.

[0064] Intensity-modulating optical elements can use, for example, polarizing beam splitters or polarizing plates. Polarization direction-modulating optical elements can use, for example, concave lenses or bandpass filters that allow only specific wavelengths of laser light to pass through.

[0065] (Item 2)

[0066] The laser intensity adjustment method in item 2 is the same as the laser intensity adjustment method in item 1, except that the optical element for changing the polarization direction is a concave lens.

[0067] (Item 5)

[0068] The laser intensity adjustment device in item 5 is the same as the laser intensity adjustment device in item 4, wherein the optical element for changing the polarization direction is a concave lens.

[0069] According to the laser intensity adjustment method in item 2 and the laser intensity adjustment device in item 5, the energy density of the laser between the polarization direction changing optical element and the intensity changing optical element can be suppressed, thus ensuring safety.

[0070] Furthermore, when a concave lens is used in the polarization direction-changing optical element, the energy density of the laser irradiating the object can be increased by placing a convex lens between the intensity-changing optical element and the object to be irradiated. Also, unlike the polarization direction-changing optical element, the rotation angle of the convex lens placed between the intensity-changing optical element and the object, which is related to the optical axis of the laser, does not affect the direction of the linearly polarized light incident on the intensity-changing optical element, and therefore does not affect the intensity adjustment range.

[0071] (Item 3)

[0072] The laser intensity adjustment method in item 3 is the same as the laser intensity adjustment method in item 1 or 2, wherein the intensity changing optical element is a polarizing beam splitter.

[0073] (Item 6)

[0074] The laser intensity adjustment device in item 6 is the same as the laser intensity adjustment device in item 4 or 5, wherein the intensity changing optical element is a polarizing beam splitter.

[0075] According to the laser intensity adjustment method in item 3 and the laser intensity adjustment device in item 6, the laser that cannot pass through due to intensity adjustment is reflected from the laser incident on the polarizing beam splitter, thereby suppressing the absorption of laser energy by the intensity-changing optical element (polarizing beam splitter), thereby suppressing the heating of the intensity-changing optical element.

[0076] (Item 7)

[0077] The quality analysis apparatus in item 7 includes:

[0078] The laser intensity adjustment device as described in any of items 4 to 6;

[0079] The sample holding section is positioned in the optical path of the laser transmitted through the intensity-changing optical element to hold the sample to be analyzed.

[0080] According to the mass analysis apparatus in item 7, the intensity of the laser irradiated when the sample is ionized in the mass analysis apparatus can be appropriately set.

[0081] Explanation of reference numerals in the attached figures

[0082] 10MALDI ion source

[0083] 11 Laser Sources

[0084] 12 Laser intensity adjustment devices

[0085] 121 Concave Lens (Optical Element for Changing Polarization Direction)

[0086] 122 Concave Lens Rotation Mechanism

[0087] 123 Polarizing Beam Splitter (Intensity Modulation Optical Element)

[0088] 1231 shielding section

[0089] 124 Polarizing Beam Splitter Rotating Mechanism

[0090] 13 reflectors

[0091] 14 Convex Lenses

[0092] 15 Sample Chambers

[0093] 151 Sample Holding Section

[0094] 16 cameras

[0095] 21. Transmission direction of the polarizing beam splitter

[0096] Polarization direction of 221 and 222 lasers

[0097] 231 Polarizing Beam Splitter Rotation Range

[0098] The intensity adjustment range of lasers 232, 233, and 234.

Claims

1. A laser intensity adjustment method, which adjusts the intensity of linearly polarized laser light, i.e., the incident laser light, to a predetermined intensity for emission, characterized in that... An intensity-changing optical element is configured, which changes the intensity of the emitted laser by allowing the polarized component of the incident laser in a predetermined transmission direction to pass through the optical path of the incident laser, and the optical element rotates about the optical axis of the incident laser within a range of at least 90° from a predetermined reference angle, so that the transmission direction is variable. A polarization direction changing optical element is configured, which is positioned further forward than the intensity changing optical element in the optical path of the incident laser to change the polarization direction of the incident laser and emit it, and the direction of the change is variable; The polarization direction changing optical element is rotated so that the polarization direction of the incident laser emitted from the polarization direction changing optical element is consistent with the transmission direction when the rotation angle of the intensity changing optical element is the reference angle. The reference angle is the angle at which the transmission direction of the intensity-changing optical element coincides with the polarization direction of the incident laser when the incident laser is incident on the intensity-changing optical element without passing through the polarization direction-changing optical element.

2. The laser intensity adjustment method as described in claim 1, wherein the polarization direction changing optical element is a concave lens.

3. The laser intensity adjustment method as described in claim 1, wherein the intensity-changing optical element is a polarizing beam splitter.

4. A laser intensity adjustment device, which adjusts the intensity of linearly polarized laser light, i.e., the incident laser light, to a predetermined intensity for emission, characterized in that... have: An intensity-changing optical element is disposed in the optical path of the incident laser, allowing the polarized component of the incident laser in a predetermined transmission direction to pass through, thereby changing the intensity of the emitted laser. The optical element rotates about the optical axis of the incident laser within a range of at least 90° from a predetermined reference angle, making the transmission direction variable. A polarization direction changing optical element is disposed further forward than the intensity changing optical element in the optical path of the incident laser, changes the polarization direction of the incident laser and emits it, and can rotate about the optical axis. The polarization direction-changing optical element rotation mechanism is configured to rotate the polarization direction-changing optical element such that the polarization direction of the incident laser emitted from the polarization direction-changing optical element is consistent with the transmission direction when the rotation angle of the intensity-changing optical element is the reference angle. The reference angle is the angle at which the transmission direction of the intensity-changing optical element coincides with the polarization direction of the incident laser when the incident laser is incident on the intensity-changing optical element without passing through the polarization direction-changing optical element.

5. The laser intensity adjustment device as described in claim 4, wherein the polarization direction changing optical element is a concave lens.

6. The laser intensity adjustment device as described in claim 4, wherein the intensity-changing optical element is a polarizing beam splitter.

7. A quality analysis device, characterized in that, have: The laser intensity adjustment device as described in claim 4; The sample holding section is positioned in the optical path of the laser transmitted through the intensity-changing optical element to hold the sample to be analyzed.

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