WO2018047547A1 - Dispositif de mesure, microscope et procédé de mesure - Google Patents

Dispositif de mesure, microscope et procédé de mesure Download PDF

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Publication number
WO2018047547A1
WO2018047547A1 PCT/JP2017/028417 JP2017028417W WO2018047547A1 WO 2018047547 A1 WO2018047547 A1 WO 2018047547A1 JP 2017028417 W JP2017028417 W JP 2017028417W WO 2018047547 A1 WO2018047547 A1 WO 2018047547A1
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Prior art keywords
light
photodetector
scattered
measurement
holding member
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PCT/JP2017/028417
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English (en)
Japanese (ja)
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泰輔 太田
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サイエンスエッジ株式会社
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Priority to JP2017563360A priority Critical patent/JP6485847B2/ja
Publication of WO2018047547A1 publication Critical patent/WO2018047547A1/fr

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J1/00—Photometry, e.g. photographic exposure meter
    • G01J1/02—Details
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B21/00—Microscopes

Definitions

  • the present invention relates to a measuring apparatus, a microscope, and a measuring method.
  • the condensing spot of laser light collected by a lens having a large numerical aperture is the basis of micro / nano technology using a laser such as a confocal laser microscope or a laser processing machine.
  • NA Numerical Aperture
  • the light intensity distribution near the focal point and the size of the focal point are important indicators that determine the performance.
  • the intensity distribution of light near the focal point when a plane wave is incident on a lens is understood as Point Spread Function (PSF, point spread function) of the lens system (lens system), and its evaluation method has been discussed.
  • PSF Point Spread Function
  • Non-Patent Document 1 the light intensity distribution in the focal plane forms a concentric bright and dark diffraction pattern called an Airy disk.
  • diffraction theory in which light is treated as a scalar wave, when the numerical aperture is small, the distance d from the center of the concentric circle to the first dark ring is derived as the following equation (1) under paraxial approximation.
  • Non-Patent Document 2 the light intensity distribution in the vicinity of the focal point deteriorates due to lens processing accuracy, aberration, misalignment, laser beam quality, and the like. For this reason, it is necessary to directly measure the light intensity distribution. Furthermore, since light is actually a vector wave with a polarization component, it has been pointed out that the intensity distribution near the focal point causes anisotropy depending on the polarization direction when the numerical aperture is large. A two-dimensional distribution evaluation method is important for spot evaluation (Non-patent Document 3).
  • the knife edge method has been proposed as a method for actually measuring the light intensity distribution in the vicinity of the focused spot of a submicron laser (Non-Patent Documents 4 and 5).
  • the knife edge method is a method for measuring a light intensity profile in one dimension.
  • Non-Patent Document 6 a method of measuring fluorescence emission intensity has been proposed (Non-Patent Document 6).
  • the laser is condensed in the epi-illumination system.
  • the fluorescent emission intensity is measured through the objective lens used for the epi-illumination while scanning the fluorescent beads sufficiently smaller than the focused spot.
  • This method is a standard method for confirming the PSF of a confocal laser fluorescence microscope.
  • Non-patent Documents 7 and 8 a method for detecting backscattering from gold nanoparticles existing in the vicinity of the focal point has been proposed (Non-patent Documents 7 and 8).
  • the laser is focused in the epi-illumination system. Then, while scanning gold nanoparticles sufficiently smaller than the focused spot, the backscattered light is guided to the interferometer through the objective lens used for epi-illumination. Thereby, the light intensity distribution and the phase distribution are measured simultaneously.
  • Non-Patent Document 9 a method for confirming the light intensity distribution of the laser focused spot in a near-field optical microscope system has been proposed.
  • the cantilever is brought close to a focused spot formed by epi-illumination without a sample. Then, the backscattered light from the tip of the cantilever is detected and observed through an objective lens used for epi-illumination.
  • Non-Patent Document 6 As a single measuring device for measuring the light intensity distribution of the focused spot, a beam proiler based on the principle of optically enlarging and imaging the focused spot of Non-Patent Document 6 is commercially available. In a commercially available beam profiler, a CCD or CMOS camera is used as an image pickup / detector instead of a photographic film.
  • the method of optically enlarging and picking up the focused spot has the following problems.
  • the aberrations of the expanding optical system (Seidel 5 aberration, chromatic aberration) are convolved. There is an influence due to misalignment of the optical adjustment of the expanding optical system.
  • the angle of collection, that is, the numerical aperture is limited by the objective lens.
  • a two-dimensional array detector such as a CCD camera or a CMOS camera that is not provided with an expansion optical system that optically expands the focused spot is also commercially available as a beam profiler.
  • the beam size that can be evaluated is limited by the pixel size of the two-dimensional array photodetector. Therefore, the minimum resolution is about 3 ⁇ m, and there is a problem that it is impossible to evaluate a sub-micron focused spot smaller than the pixel size.
  • Non-Patent Documents 6 to 9 In the methods of Non-Patent Documents 6 to 9 in which the laser is condensed in the epi-illumination system and the fluorescence emission and the back-scattered light are detected through the objective lens used for the epi-illumination, the measurement device is separated from the measurement object. It cannot be a single measuring device.
  • Non-Patent Document 6 since the method of measuring the fluorescence intensity of the fluorescent beads in Non-Patent Document 6 uses fluorescence, there are restrictions on the wavelength of laser light that can be excited by fluorescence. Further, there is a problem that the fluorescent material is faded.
  • the present invention has been made in view of the above-described problems, and an object thereof is to provide a measuring apparatus, a microscope, and a measuring method capable of accurately measuring the spatial distribution of light intensity at a focused spot. .
  • the measuring apparatus is a particle that is disposed in or near the focal point of a light beam, scatters light to generate scattered light, and forward scattered light scattered in front of the particle, And a photodetector that detects the intensity of scattered light at an angle larger than the maximum divergence angle corresponding to the maximum condensing angle that forms the focal point, and a drive unit that changes the relative position of the particles with respect to the focal point. It is a thing.
  • the measurement apparatus includes a holding surface on which the particles are arranged, and is arranged between a holding member that transmits the light beam and the scattered light, the holding surface, and the photodetector. There may be further provided a light shielding unit that shields scattered light at an angle smaller than the divergence angle and divergent light of the light beam not scattered by the particles. The divergent light of the light beam that is not scattered by the particles can be shielded.
  • the measuring apparatus may further include a holding member having a holding surface on which the particles are arranged, and the light detector may detect the scattered light that has passed through the holding member.
  • the holding member has a convex surface facing the holding surface, the convex surface is a spherical surface or a paraboloid, and the holding surface is a flat surface.
  • the facing surface of the holding member facing the holding surface may be a flat surface, and the facing surface and the photodetector may be in contact with each other.
  • the measuring device is disposed between the holding surface and the photodetector, and shields light scattered to an angle smaller than the maximum divergence angle and divergent light of a light beam that is not scattered by the particles. Further, the light detector may detect scattered light that has passed outside the light shielding portion.
  • the light shielding portion may be provided between the holding surface and the convex surface of the holding member. Thereby, the number of parts of the measurement optical system can be reduced.
  • the position of the light shielding part may be an arbitrary position from the particle to the light detection part.
  • the light shielding part is a light shielding plate provided between the convex surface of the holding member and the photodetector, the light shielding plate can be easily replaced.
  • light shielding plates of different sizes are prepared according to the lens NA.
  • a light shielding plate having a size suitable for a different NA can be selected and replaced. Thereby, lenses with different NAs can be easily measured.
  • the photodetector may be larger in size than the light shielding portion.
  • the maximum scattering angle of the scattered light that can be shielded by the light-shielding unit with respect to the optical axis is set as ⁇ 1 , and the optical axis is used as the reference. If the maximum scattering angle of the scattered light can be light detector detects was theta 2, it is preferable to satisfy ⁇ 1 ⁇ cos -1 (1 / ⁇ 3) ⁇ 2 relationship.
  • the driving unit may move the particles and the holding member with respect to the focal point.
  • the measurement apparatus may further include a lens disposed between the convex surface of the holding member and the photodetector, and the photodetector may detect a light beam refracted by the lens. . Thereby, the size of the photodetector can be reduced.
  • the scattering angle of the scattered light that can be detected by the photodetector is limited to be within a predetermined angle range, and the measurement conditions regarding the angle range are changed, Measurement may be performed, and the electric field component of the light may be calculated based on measurement results under a plurality of measurement conditions.
  • the photodetector is a two-dimensional array detector in which a plurality of light receiving elements are arranged as pixels, and the measurement conditions are set according to the arrangement of the pixels of the two-dimensional array detector. Different pixels may measure the scattered light, and measurement under the plurality of measurement conditions may be performed.
  • the measurement conditions may be changed by changing at least one of the shape and size of the light-shielding portion arranged between the photodetector and the particles.
  • the photodetector is a photodiode.
  • the particles may be metal particles.
  • a scattering cross section can be enlarged and scattered light intensity
  • strength can be made high.
  • the microscope according to the present embodiment includes the measurement device, a sample stage on which the measurement device is mounted, an illumination light source, and an objective lens that collects a light beam from the illumination light source to form the focal point. , With. Thereby, observation with a microscope and measurement with a measuring device can be easily switched.
  • a measuring method includes: a step of condensing a light beam to form a focal point; and forward scattered light scattered in front of particles placed in or near the focal point. Detecting the intensity of the scattered light at an angle greater than the maximum divergence angle corresponding to the maximum collection angle forming, and changing the relative position of the particles with respect to the focal point. Thereby, the spatial distribution of light intensity can be measured accurately.
  • the measuring apparatus is arranged in or near the focal point of a light beam, and generates a scattered light by scattering the light, and a photodetector for detecting the intensity of the scattered light scattered by the particle.
  • the scattering angle at the particles of the scattered light that can be detected by the photodetector is limited, and the measurement is performed by changing measurement conditions related to the angle range.
  • the electric field component of the light is calculated based on the measurement result.
  • the present invention it is possible to provide a measuring apparatus, a microscope, and a measuring method capable of accurately measuring the spatial distribution of light intensity at a focused spot.
  • FIG. 1 It is a figure for demonstrating the principle of the measuring apparatus concerning this Embodiment. It is a figure which shows the working distance of an objective lens. It is a figure which shows the scattered light in a gold nanoparticle. It is a figure which shows the measurement optical system of a measuring device. It is a figure for demonstrating the maximum condensing angle of condensed light, and the maximum divergence angle of diverging light. It is a figure which shows the structure which mounted the gold nanoparticle on the holding member of a parallel plate. It is a figure for demonstrating refraction of the light which permeate
  • FIG. 6 is a diagram illustrating a measurement optical system according to a second embodiment. It is a figure which shows the example of arrangement
  • FIG. FIG. 6 is a diagram illustrating a measurement optical system according to a third embodiment. It is a figure which shows the example of arrangement
  • FIG. It is a figure which shows the external appearance of a measuring apparatus, and a control structure. It is sectional drawing which shows the structure of a measuring apparatus. It is a top view which shows the structure of a light-shielding part. It is a figure which shows the structure of a microscope. It is a figure which shows the measurement result of an Example and a comparative example.
  • FIG. 10 is a diagram illustrating a configuration of a measuring apparatus according to a modification example of the fourth embodiment. It is a figure for demonstrating a three-dimensional polar coordinate system. It is a graph which shows the relationship between (theta) and F ((theta)). It is a figure for demonstrating the 1st method of changing measurement conditions. It is a figure for demonstrating the 2nd method of changing measurement conditions. It is a figure for demonstrating the 3rd method of changing measurement conditions. It is a top view which shows the specific structure of the light-shielding part used with the 3rd method.
  • FIG. 9 is a diagram schematically illustrating a configuration of a measurement apparatus according to a sixth embodiment.
  • FIG. 10 is a diagram schematically showing another configuration of the measuring apparatus according to the sixth embodiment.
  • the light intensity distribution near the condensing spot is an indicator of the spatial resolution of the laser microscope.
  • the light intensity density which is the light intensity per unit area, is also an important index in the laser microscope.
  • the laser microscope the laser light is condensed to a size of submicron, and the light intensity density is very high.
  • a high-intensity laser is used in a laser Raman microscope using Raman spectroscopy having a small scattering cross section. For this reason, it is an analysis / measurement method that always pays attention to laser damage to the sample.
  • the intensity of the laser beam applied to the sample from the objective lens can be measured easily. However, there is no direct measurement method of the focal spot size or light intensity distribution. For this reason, the light intensity density has so far been estimated. Since the light intensity distribution can be directly measured using the measuring apparatus according to the present embodiment, accurate knowledge of the loss threshold of the sample is brought about, and simplification of the measurement can be expected. In other measurement methods / analytical methods that actively use the interaction between light and materials, such as laser technology such as LIBS (Laser Induced Breakdown Spectroscopy), laser processing, photopolymerization of polymers, etc. It is expected that the measurement method will help.
  • LIBS Laser Induced Breakdown Spectroscopy
  • Embodiment 1 The measuring apparatus according to the present embodiment is arranged in or near the focal point of a light beam, and generates a scattered light by scattering light, forward scattered light scattered in front of the particle, and a focal point.
  • a photodetector that detects the intensity of scattered light at an angle larger than the maximum divergence angle corresponding to the maximum condensing angle that forms and a drive unit that changes the relative position of the particles with respect to the focal point. is there. Therefore, the measuring apparatus and measuring method according to the present embodiment measure the spatial distribution of the light intensity in and near the condensing spot of the light beam condensed by the lens.
  • the measuring device measures the spatial distribution of light intensity in and near the condensing spot of the objective lens of the laser microscope.
  • FIG. 1 is a diagram for explaining the measurement principle used in the measurement apparatus and the measurement method according to the present embodiment.
  • the objective lens 51 condenses the illumination light L ⁇ b> 1, thereby forming a condensing spot S ⁇ b> 1 at the focal point of the objective lens 51.
  • Gold nanoparticles 11 are arranged in the condensing spot S1. Due to the diffraction limit, the focused spot S1 has a finite size. The gold nanoparticle 11 is sufficiently smaller than the condensing spot S1. Furthermore, the gold nanoparticles 11 are sufficiently smaller than the wavelength of the illumination light L1. The size of the gold nanoparticle 11 is, for example, 40 nm.
  • the particle is subject to the dipole approximation.
  • the amplitude (electric field) of the scattered light that is scattered is proportional to the electric field (E) of the light in which the particles are present.
  • the intensity I of light is proportional to the square of the electric field (E 2 ).
  • the light intensity of the illumination light L1 in the gold nanoparticle 11 can be measured by detecting the scattered light scattered by the gold nanoparticle 11. Moreover, the spatial distribution of light intensity can be measured by moving the gold nanoparticles 11. When scattered light is detected, unlike fluorescence, phenomena such as fluorescence fading do not occur. In addition, since any light is scattered by the gold nanoparticles 11, the wavelength of the illumination light L1 is not limited. The intensity of the scattered light still depends on the wavelength of the light, the particle size, and the dielectric constant of the particle and field.
  • the working distance of the objective lens of the microscope is WD.
  • the WD With a 100 ⁇ objective lens and NA of 0.9, the WD is 0.1 to 1 mm.
  • the numerical aperture NA is expressed by the following formula (2).
  • Numerical aperture NA n ⁇ sin ⁇ (2)
  • ⁇ Condensing angle (angle between the optical axis and the outermost condensed light beam)
  • the scattered light scattered by the gold nanoparticles 11 has a light intensity that depends on the scattered direction ⁇ with the axis of the induced dipole as the axis of rotational symmetry.
  • the intensity of the scattered light by the gold nanoparticles 11 is represented by the following formula (3).
  • C is a proportionality constant.
  • Scattering in the gold nanoparticles 11 is divided into back scattering and forward scattering as shown in FIG. That is, the backscattered light becomes scattered light from the gold nanoparticles 11 toward the objective lens 51 side.
  • the backscattered light propagates in a direction approaching the objective lens 51 (upward direction in FIG. 3).
  • the forward scattered light becomes scattered light that travels from the gold nanoparticle 11 toward the side opposite to the objective lens 51. That is, the forward scattered light propagates in a direction away from the objective lens 51 (lower side in FIG. 3).
  • the scattered light can be detected without passing through the objective lens 51, the measurement object and the measurement device can be separated.
  • the WD of the objective lens 51 having a high magnification and a high NA is 1 mm or less. For this reason, it is substantially impossible to arrange a photodetector or the like between the focused spot and the objective lens 51. Therefore, in the measuring apparatus according to the present embodiment, the forward scattered light is detected by the photodetector 21 arranged in front of the gold nanoparticles 11.
  • the light intensity of the scattered light can be measured without using the objective lens 51.
  • the illumination light L ⁇ b> 1 that is not scattered by the gold nanoparticles 11 is also detected by the photodetector 21. Since the scattered light is Rayleigh scattered light, it has the same wavelength as the illumination light L1. Therefore, the scattered light and the illumination light L1 cannot be separated by a dichroic mirror or a wavelength filter.
  • FIG. 4 shows a measurement optical system 101 of the measurement apparatus according to this embodiment.
  • the measurement optical system 101 includes gold nanoparticles 11, a holding member 12, a light shielding unit 13, and a photodetector 21.
  • the holding member 12, the light shielding unit 13, and the photodetector 21 are arranged on the front side (lower side in FIG. 4) of the objective lens 51.
  • the holding member 12 is disposed below the objective lens 51 so as to face the objective lens 51.
  • the light shielding unit 13 is disposed below the holding member 12.
  • the photodetector 21 is disposed below the light shielding unit 13.
  • the vertical direction in the present embodiment is a direction in the drawing and is relative to the actual arrangement direction. That is, in the present embodiment, the configuration in which the illumination light L1 propagates downward and enters the objective lens 51 is described.
  • the light which advances without being scattered by the gold nanoparticle 11 among illumination light L1 is shown as the diverging light L3.
  • the diverging light L3 travels while spreading in a direction away from the focal point (downward direction in FIG. 4).
  • the objective lens 51 condenses the illumination light L1.
  • the illumination light L1 is, for example, a monochromatic light beam from a laser light source.
  • the gold nanoparticles 11 are arranged in the condensing spot of the illumination light L1 collected by the objective lens 51 as described above.
  • the gold nanoparticles 11 are placed on the holding member 12.
  • the holding member 12 holds the gold nanoparticles 11.
  • other metal particles such as silver nanoparticles may be used.
  • metal particles such as gold nanoparticles 11 the scattering cross section can be increased, and the detected scattered light intensity can be increased.
  • the particles held by the holding member 12 may be fine particles that scatter incident light.
  • the gold nanoparticle 11 has a size smaller than the wavelength of the illumination light L1 and the focused spot.
  • the holding member 12 is a light transmitting member having a light transmitting property, and is formed of, for example, glass or resin.
  • the holding member 12 includes a holding surface 12a and a convex surface 12b.
  • the holding surface 12 a is disposed toward the objective lens 51.
  • the convex surface 12b is disposed to face the holding surface 12a.
  • the holding surface 12a is a flat upper surface, and the convex surface 12b is a lower surface curved so as to protrude downward.
  • the convex surface 12b is a spherical surface.
  • the convex surface 12b may be an aspheric surface such as a paraboloid.
  • the holding member 12 can be hemispherical glass or semiparabolic glass. Further, the center of curvature of the convex surface 12b is near the intersection of the optical axis OX of the objective lens 51 and the holding surface 12a.
  • the gold nanoparticles 11 are arranged on the holding surface 12a.
  • the illumination light L1 is scattered by the gold nanoparticles 11.
  • the scattered light L2 is scattered in all directions.
  • the scattered light heading forward is referred to as scattered light L2.
  • the scattered light L2 travels while diverging.
  • the scattered light L2 passes through the holding member 12. That is, the scattered light L2 passes through the holding surface 12a and propagates inside the holding member 12. And the scattered light L2 comes out of the holding member 12 through the convex surface 12b.
  • the scattered light L2 passes through the convex surface 12b and propagates in the space below the holding member 12.
  • the divergent light L3 that has not been scattered also exits outside the holding member 12 via the convex surface 12b.
  • a light shielding portion 13 is disposed below the holding member 12. Therefore, the holding member 12 is disposed between the light shielding unit 13 and the objective lens 51.
  • the light shielding unit 13 is disposed on the optical axis OX of the objective lens 51.
  • the light shielding unit 13 is, for example, a circular light shielding plate.
  • the light shielding portion 13 is formed of a resin or a metal plate. By making the light shielding part 13 black, it is possible to prevent stray light from being detected. Scattered light L2 emitted from the convex surface 12b is incident on the light shielding portion 13.
  • the scattered light L2 incident on the light shielding portion 13 is shielded. Further, the diverging light L3 that has not been scattered by the gold nanoparticles 11 also passes through the holding member 12 and enters the light shielding portion 13. Therefore, the light shielding unit 13 shields the diverging light L3.
  • the light shielding portion 13 has a size that can restrict the passage of the diverging light L3 from the holding member 12. Thereby, it is possible to prevent the diverging light L3 from being detected by the photodetector 21.
  • a light detector 21 is disposed under the light shielding portion 13. That is, the light shielding portion 13 is disposed between the convex surface 12 b of the holding member 12 and the photodetector 21.
  • the photodetector 21 is larger than the light shielding unit 13. That is, the photodetector 21 is disposed so as to protrude from the light shielding portion 13 in a plan view orthogonal to the optical axis OX. Therefore, the photodetector 21 detects the scattered light L2 that has passed through the outside of the light shielding unit 13.
  • FIG. 5 is a diagram showing diverging light and condensed light in the vicinity of the focal point.
  • the light condensed toward the focal point by the objective lens 51 is shown as the condensed light L4. That is, in the illumination light L1, the light before passing through the focal point becomes the condensed light L4, and the light after passing through the focal point becomes the diverging light L3.
  • the holding member 12 is omitted for explanation. Yes.
  • the maximum condensing angle of the condensed light L4 that is condensed by the objective lens 51 and goes to the focal point is ⁇ 4.
  • the maximum divergence angle of the diverging light L3 that diverges from the focal point is ⁇ 3.
  • the divergent light L3 is light that travels without being scattered by the gold nanoparticles 11 in the illumination light L1 as described above.
  • the maximum divergence angle ⁇ 3 corresponds to the maximum light collection angle ⁇ 4.
  • the maximum divergence angle ⁇ 3 is equal to the maximum light collection angle ⁇ 4. Since the refractive index of the holding member 12 is larger than the refractive index of air, the diverging light L3 is refracted by the holding surface 12a. Therefore, when the diverging light L3 of the maximum diverging light ⁇ 3 is refracted by the holding surface 12a, it propagates at a diverging angle smaller than the maximum condensing angle ⁇ 4.
  • the light shielding unit 13 has a size capable of shielding all the diverging light L3. More specifically, the light shielding unit 13 has a minimum size that can shield the diverging light L3.
  • the size of the light shielding unit 13 is determined by the NA of the objective lens 51, the distance from the particles (the distance from the holding surface 12a), the refractive index of the holding member 12, and the like.
  • the light shielding unit 13 shields the scattered light L2 scattered forward by an angle smaller than the maximum divergence angle and the divergent light L3 of the light beam that is not scattered by the gold nanoparticles 11.
  • the photodetector 21 detects the scattered light L2 scattered forward at an angle larger than the maximum divergence angle of the objective lens 51.
  • the photodetector 21 detects the scattered light L2 from the gold nanoparticles 11. Then, the photodetector 21 outputs a detection signal corresponding to the scattered light intensity.
  • the intensity of the scattered light from the gold nanoparticles 11 changes according to the intensity of the illumination light L1 at the position of the gold nanoparticles 11. Specifically, the scattered light intensity is proportional to the illumination light intensity. Therefore, the scattered light intensity detected by the photodetector 21 indicates the intensity of the illumination light L1 at the position of the gold nanoparticles 11.
  • the gold nanoparticle 11 is smaller than the focused spot. Therefore, the illumination light intensity at the position of the gold nanoparticles 11 in the focused spot can be measured.
  • the holding member 12 that holds the gold nanoparticles 11 is moved so that the gold nanoparticles 11 scan the focused spot.
  • the holding member 12, the light shielding unit 13, and the photodetector 21 are moved together.
  • the gold nanoparticles 11, the holding member 12, the light shielding unit 13, and the photodetector 21 can be moved relative to the focused spot.
  • the light shielding part 13 or the photodetector 21 may be configured not to move together with the gold nanoparticles 11.
  • only the holding member 12 may be moved together with the gold nanoparticles 11.
  • the holding member 12 and the light shielding part 13 may be moved together with the gold nanoparticles 11.
  • the holding member 12 and the photodetector 21 may be moved together with the gold nanoparticles 11.
  • the spatial distribution of the intensity of the illumination light L1 can be measured by moving the position of the gold nanoparticles 11. For example, by moving the gold nanoparticles 11 in a plane orthogonal to the optical axis OX, the two-dimensional distribution of the illumination light intensity at the focused spot can be measured. Furthermore, by moving the position of the gold nanoparticle 11 along the optical axis OX, it is possible to measure the three-dimensional distribution of the illumination light intensity at the focused spot. Thus, by using the measurement optical system 101, it is possible to accurately measure the spatial distribution of the illumination light intensity at the focused spot. The size of the focal point of the laser beam can be accurately measured. It is also possible to accurately measure the power density of laser light.
  • the measurement optical system 101 can have a simple configuration. Therefore, the measuring device can be reduced in size.
  • FIG. 6 is a diagram showing a configuration using a parallel plate holding member 112.
  • FIG. 7 is a diagram showing light refraction in the parallel plate holding member 112.
  • the holding member 112 is a plane in which two opposing surfaces (upper surface and lower surface) are parallel.
  • Gold nanoparticles 111 are arranged on the holding member 112.
  • a light shielding portion 113 is disposed below the holding member 112.
  • a photodetector 121 is disposed under the light shielding portion 113.
  • the holding member 12 and the holding member 112 are formed of a transparent material such as glass or resin, for example. These transparent materials have a refractive index greater than that of air. Therefore, light is refracted at the interface between the holding member 112 and air.
  • n 1 be the refractive index of air
  • n 2 be the refractive index of the transparent material (for example, glass) constituting the holding member 112.
  • the refraction angles ⁇ 1 and ⁇ 2 in FIG. 7 are expressed by the following equation (4).
  • n 2 / n 1 sin ⁇ 1 / sin ⁇ 2 (4)
  • ⁇ is the wavelength of the illumination light L1.
  • the lower surface of the holding member 12 is a spherical surface. When the condensing spot is formed in the vicinity of the center of curvature, the incident angle at which the scattered light L2 enters the convex surface 12b can be close to 90 °.
  • Scattered light from the gold nanoparticles 11 arranged on the surface of the holding surface 12a of the holding member 12 is refracted when entering the holding surface 12a.
  • Snell's law reduces the divergence angle of the focused beam and the scattering angle of the scattered light (relaxing the restrictions).
  • the diverging light L3 and the scattered light L2 propagating from the gold nanoparticle 11 to the photodetector 21 are along the normal direction of the interface between the holding member 12 and air. Incident. For this reason, the diverging light L3 and the scattered light L2 propagate without changing the angle (while maintaining a small diverging angle).
  • the light detector 21 since the light detector 21 only needs to receive the scattered light L2, it is not necessary to use a two-dimensional array detector such as a CCD or CMOS as the light detector 21.
  • the photodetector 21 can be a point sensor such as a photodiode.
  • the measurement optical system 101 can be made into a simple structure. Thereby, a measuring apparatus can be reduced in size.
  • the height (thickness) of the measuring device can be about 25 mm to 50 mm.
  • the width in the plane orthogonal to the optical axis can be set to a size of 150 mm or less.
  • Modification 1 of the measurement optical system 101 is shown in FIG.
  • the position of the light-shielding portion 13 is different from the configuration of FIG.
  • the light shielding portion 13 is provided inside the holding member 12. That is, the light shielding portion 13 is disposed between the holding surface 12 a and the convex surface 12 b of the holding member 12. Except for the arrangement of the light-shielding portion 13, the description is omitted because it is the same as in the first embodiment.
  • the objective lens 51 is omitted.
  • the light shielding unit 13 shields the scattered light L2 at an angle smaller than the maximum divergence angle corresponding to the maximum condensing angle that forms the focal point, and the divergent light L3 of the light beam that is not scattered by the gold nanoparticles 11.
  • the light shielding portion 13 only needs to be disposed on the front side of the holding surface 12a.
  • the light shielding part 13 can be formed by coloring the inside or the surface of the holding member 12 to black.
  • the light shielding portion 13 can be formed integrally with the holding member 12. Therefore, since it is necessary to provide the light shielding portion 13 separately from the holding member 12, the number of parts can be reduced. Further, since the distance between the holding member 12 and the photodetector 21 can be shortened, the photodetector 21 can be reduced in size. Therefore, the measurement optical system 101 can be further downsized.
  • the light shielding portion 13 may be formed by coating the convex surface 12b of the holding member 12 or the surface of the photodetector 21 with a substance that does not transmit light.
  • the light-shielding portion 13 can be formed by depositing or sputtering a thin film such as a metal or a dielectric. Thereby, the number of parts can be reduced.
  • the light shielding portion 13 is formed of a member different from the holding member 12. Therefore, since the replacement of the light shielding unit 13 is facilitated, the size of the light shielding unit 13 can be easily adjusted. That is, by preparing a plurality of light shielding plates having different sizes, the size and position of the light shielding unit 13 can be easily adjusted.
  • FIG. A measurement optical system 102 of the measurement apparatus according to this embodiment is shown in FIG.
  • the measurement optical system 102 includes a condenser lens 15 in addition to the measurement optical system 101.
  • one condenser lens 15 is disposed as a relay lens between the holding member 12 and the photodetector 21.
  • the condensing lens 15 is disposed between the light shielding portion 13 and the photodetector 21.
  • the condensing lens 15 condenses the scattered light L ⁇ b> 2 that has passed through the outside of the light shielding unit 13 on the photodetector 21.
  • the light reception size of the photodetector 21 can be made small compared with Embodiment 1 and its modification.
  • the photodetector 21 can be made smaller than the light shielding unit 13.
  • FIG. 10 is a diagram illustrating an arrangement example of the light shielding unit 13.
  • the light shielding unit 13 shields the scattered light L2 at an angle smaller than the maximum divergence angle corresponding to the maximum condensing angle that forms the focal point, and the divergent light L3 of the light beam that is not scattered by the gold nanoparticles 11.
  • the holding surface 12a and the photodetector 21 are located on a conjugate plane (a position where a particle image is projected).
  • the scattered light L2 is collected by the photodetector 21 and has a minimum size.
  • the size of the photodetector 21 can be reduced.
  • the conjugate surface if the gold nanoparticle 11 positioned on the holding surface 12a is in the image of the size of the photodetector 21, the scattered light L2 is detected.
  • the size of the light shielding unit 13 is set larger than the size capable of blocking the light beam having the maximum divergence angle of the divergent light L3. Furthermore, the size of the light shielding unit 13 takes a margin larger than the XY scanning range.
  • the light shielding portion 13 a is disposed inside the holding member 12.
  • the light shielding part 13 b is disposed between the convex surface 12 b and the condenser lens 15.
  • the light shielding portion 13 c is disposed inside the condenser lens 15.
  • the light shielding unit 13 d is disposed between the condenser lens 15 and the photodetector 21.
  • the illumination light L1 may be blocked at any position indicated by the light blocking portions 13a to 13d. Then, the photodetector 21 detects the scattered light L2 that has passed through the outside of the light shielding unit 13.
  • the light-shielding part 13 may be formed by depositing or sputtering a thin film such as a metal or a dielectric.
  • FIG. A measurement optical system 103 of the measurement apparatus according to this embodiment is shown in FIG.
  • the measurement optical system 103 includes a collimating lens 14 in addition to the measurement optical system 102.
  • the condensing lens 15 and the collimating lens 14 are arranged as a relay lens between the holding member 12 and the photodetector 21.
  • the collimating lens 14 is disposed between the condenser lens 15 and the holding member 12.
  • the collimating lens 14 converts the scattered light L2 that has passed through the outside of the light shielding portion 13 into a parallel light flux.
  • the condensing lens 15 condenses the scattered light L2 from the collimating lens 14 onto the photodetector 21.
  • the scattered light L ⁇ b> 2 is condensed on the photodetector 21 by the collimating lens 14 and the condenser lens 15. By doing in this way, the light reception size of the photodetector 21 can be made small compared with Embodiment 1 and its modification.
  • FIG. 12 is a diagram illustrating an arrangement example of the light shielding unit 13.
  • the light shielding unit 13 shields the scattered light L2 at an angle smaller than the maximum divergence angle corresponding to the maximum condensing angle that forms the focal point, and the divergent light L3 of the light beam that is not scattered by the gold nanoparticles 11.
  • the light shielding portion 13 e is disposed inside the holding member 12.
  • the light shielding portion 13f is disposed between the convex surface 12b and the collimating lens 14.
  • the light shielding portion 13g is disposed inside the collimating lens 14.
  • the light shielding unit 13 h is disposed between the collimating lens 14 and the condenser lens 15.
  • the light shielding unit 13 i is disposed inside the condenser lens 15.
  • the light shielding unit 13j is disposed between the condenser lens 15 and the photodetector 21.
  • the illumination light L1 may be blocked at any position indicated by the light blocking portions 13e to 13j. Then, the photodetector 21 detects the scattered light L2 that has passed through the outside of the light shielding unit 13.
  • the light shielding portion 13 is formed by coating the convex surface 12 b of the holding member 12, the surface of the collimating lens 14, the surface of the condenser lens 15, or the surface of the photodetector 21 with a substance that does not transmit light. Good.
  • the light-shielding portion 13 can be formed by depositing or sputtering a thin film such as a metal or a dielectric.
  • the surface facing the holding surface 12a of the holding member 12 is not limited to the convex surface 12b.
  • the surface facing the holding surface 12a may be a flat surface.
  • the holding member 112 having the configuration shown in FIG. 6 can be used. That is, the upper surface of the holding member 112 is a holding surface that holds the gold nanoparticles 111.
  • the lower surface facing the holding surface is a plane parallel to the holding surface.
  • the position of the light shielding portion 13 is not particularly limited.
  • the condensing lens 15 and the collimating lens 14 described in Embodiment 2 or 3 may be disposed between the holding member 112 and the photodetector 121.
  • FIG. 13 is a diagram illustrating an appearance of the measuring apparatus 100 and a control configuration.
  • FIG. 13 is a perspective view of the appearance of the measuring apparatus 100.
  • FIG. 14 is a cross-sectional view showing the internal configuration of the main body of the measuring apparatus 100.
  • FIG. 14 shows an example using the measurement optical system 103. That is, the collimating lens 14 and the condenser lens 15 are disposed between the holding member 12 and the photodetector 21.
  • the measuring apparatus 100 includes a main body 40, a controller 41, and a personal computer 42.
  • the main body 40 includes the measurement optical system 103 described above. Therefore, the main body 40 has a housing 10 that houses the measurement optical system 103.
  • the size of the main body 40 is, for example, 100 mm ⁇ 100 mm ⁇ 27 mm.
  • the housing 10 is a rectangular parallelepiped box.
  • a measurement optical system 103 is disposed inside the housing 10.
  • the holding surface 12 a of the holding member 12 is exposed on the upper surface of the housing 10, and the gold nanoparticles 11 are arranged on the holding surface 12 a of the holding member 12.
  • the holding member 12 is, for example, a high refractive index hemispherical glass having a refractive index of 2.0.
  • a plurality of gold nanoparticles 11 are dispersed on the holding surface 12a.
  • a plurality of gold nanoparticles 11 are dispersed on the holding surface 12a so that one gold nanoparticle 11 is arranged in the focused spot.
  • the size of the focused spot is about 1 ⁇ m.
  • the first lens barrel 32 holds the holding member 12 and the collimating lens 14. That is, the holding member 12 and the collimating lens 14 are fixed in the first lens barrel 32.
  • the second lens barrel 33 holds the first lens barrel 32 and the condenser lens 15.
  • the first lens barrel 32 is disposed inside the second lens barrel 33.
  • the first lens barrel 32 is detachably attached to the second lens barrel 33.
  • the condenser lens 15 is fixed in the second lens barrel 33.
  • a light shielding portion 13 is provided between the first lens barrel 32 and the second lens barrel 33. By removing the first lens barrel 32, the light shielding portion 13 can be replaced.
  • the photodetector 21 is disposed below the second lens barrel 33.
  • the photodetector 21 is a photodiode having a chip size of 3.6 mm ⁇ 3.6 mm.
  • the second lens barrel 33 is attached to the housing 10 via the drive unit 31.
  • the drive unit 31 is a three-dimensional piezo scanner in the XYZ directions.
  • the drive unit 31 moves the second lens barrel 33 with respect to the housing 10.
  • the Z direction is a height direction, that is, a direction parallel to the optical axis of the objective lens.
  • the XY plane is a plane perpendicular to the Z direction.
  • the XY directions are directions orthogonal to each other.
  • the drive unit 31 can move the second lens barrel 33 at a pitch of 1 nm.
  • the holding member 12, the light shielding unit 13, the collimating lens 14, the condenser lens 15, and the photodetector 21 attached to the second lens barrel 33 are moved. Therefore, the gold nanoparticles 11 held by the holding member 12 scan the focused spot.
  • the detector 21 measures the intensity of the scattered light L2 while scanning by the driving unit 31. Thereby, the spatial distribution of the light intensity of the illumination light L1 at the condensed spot can be measured.
  • a controller 41 is connected to the housing 10.
  • the controller 41 supplies power to the drive unit 31 and performs XYZ control of the drive unit 31. Further, the detection signal (voltage) from the photodetector 21 is output to the controller 41.
  • the controller performs A / D conversion on the voltage value of the detection signal corresponding to the light intensity and outputs it to the personal computer 42.
  • the personal computer 42 is a processing device including a storage unit that stores a detection signal and a display unit that displays a spatial distribution of light intensity.
  • the drive unit 31 moves the second lens barrel 33 in each of the XYZ directions. By associating the XYZ position of the second lens barrel 33 with the detection value of the detection signal, a three-dimensional distribution of light intensity can be measured.
  • FIG. 15 shows an example of the configuration of the light shielding unit 13.
  • FIG. 15 is a plan view showing the configuration of the light shielding unit 13.
  • the light shielding unit 13 is a circular plate.
  • the light shielding portion 13 is connected to the outer frame 35 via a connecting portion 36.
  • the outer frame 35 is a ring arranged outside the light shielding unit 13.
  • An outer frame 35 is held between the first lens barrel 32 and the second lens barrel 33.
  • the light shielding part 13 and the outer frame 35 are connected via a connecting part 36.
  • the four connection parts 36 are provided radially.
  • a space 37 is formed between the light shielding portion 13 and the outer frame 35 in the radial direction. That is, the scattered light L ⁇ b> 2 that has passed through the space 37 inside the outer frame 35 outside the light shielding portion 13 is detected by the photodetector 21.
  • the outer frame 35, the light shielding part 13, and the connecting part 36 are integrally formed of resin. Moreover, it is preferable that the light shielding part 13 has a low reflectance.
  • the outer frame 35, the light shielding part 13, and the connecting part 36 are painted black. By doing so, it is possible to prevent stray light from being detected.
  • the size of the light shielding portion 13 may be changed. That is, the optimum size of the light shielding unit 13 varies depending on the NA of the objective lens 51. Therefore, the light shielding unit 13 having the light shielding unit 13 having a size corresponding to the NA of the objective lens 51 is prepared.
  • the condensing spot of the objective lens 51 having a small NA can be measured, but the detected light amount becomes small. That is, the larger the size of the light shielding portion 13, the more scattered light L2 that is shielded. For this reason, what is necessary is just to use the light-shielding part 13 of the size as small as possible in the range which can shield the illumination light L1.
  • FIG. 16 is a diagram illustrating a microscope 200 on which the main body 40 of the measuring apparatus 100 is mounted.
  • the microscope 200 includes a sample table 60 disposed immediately below the objective lens 51. During actual observation, a sample is placed on the sample table 60.
  • the main body 40 of the measuring apparatus 100 is placed on the sample stage 60.
  • a plurality of objective lenses 51 are attached to the revolver 68. When measuring the objective lens 51 having a different NA, the light shielding unit 13 is replaced as described above.
  • the microscope 200 includes a light source 61, a mirror 62, a mirror 63, a beam expander 64, a mirror 65, a mirror 66, a polarizing beam splitter (PBS) 67, a revolver 68, an objective lens 51, a sample stage 80, a half mirror 70, and an imaging lens. 71, a camera 72, an LED light source 81, a lens 82, and a lens 83.
  • PBS polarizing beam splitter
  • the light source 61 is a laser light source and generates illumination light L1 having a wavelength of 532 nm.
  • the illumination light L1 emitted from the light source 61 has a beam diameter of 1 mm, for example.
  • the illumination light L 1 is reflected by the mirrors 62 and 63 and enters the beam expander 64.
  • the beam expander 64 expands the beam diameter.
  • the beam diameter is expanded to 5 mm.
  • the illumination light L 1 from the beam expander 64 is reflected by the mirrors 65 and 66 and enters the PBS 67.
  • the PBS 67 transmits or reflects light according to the polarization state.
  • the illumination light L 1 reflected by the PBS 67 is incident on the objective lens 51.
  • the illumination light L1 collected by the objective lens 51 is incident on the gold nanoparticles 11 provided in the main body 40 as described above (see also FIG. 13 and the like). And the photodetector 21 shown by FIG. 14 etc. detects the scattered light L2 from the gold nanoparticle 11.
  • the drive unit 31 moves the measurement optical system 103 while the illumination light L1 is irradiated. By doing in this way, the light intensity distribution of the illumination light L1 in the condensing spot (focus) of the objective lens 51 can be measured.
  • the microscope 200 is provided with a half mirror 70, an imaging lens 71, and a camera 72 as an optical system for imaging the sample.
  • An LED light source 81, a lens 82, and a lens 83 for an LED illumination optical system are provided. Description of these will be omitted.
  • the height clearance of the sample on the sample stage 80 is usually about 35 mm to 50 mm. Further, since the thickness of the main body 40 is 27 mm, it can be installed on the sample stage 80. Therefore, the light intensity distribution of the illumination light L1 can be easily measured. Then, after the measurement is completed, it is only necessary to remove the main body 40 from the sample stage 80. Therefore, the sample can be observed with illumination by the light source 61. Therefore, it is possible to easily switch between observation of the sample with the microscope 200 and measurement of the illumination light L1 with the measurement apparatus 100.
  • the light shielding portion 13 may be replaced according to the NA of the objective lens 51 as described above. Therefore, measurement for each objective lens 51 can be easily performed.
  • FIG. 17 and 18 show the measurement results of the measuring apparatus according to this example.
  • FIG. 17 is a diagram illustrating a profile of illumination light intensity in the X direction and the Y direction, and a spatial distribution in the XY plane.
  • FIG. 18 is a diagram illustrating a profile of illumination light intensity in the Z direction and a spatial distribution in the XZ plane.
  • the simulation result obtained by the method described in the nonpatent literature 3 is shown as a comparative example.
  • the laser wavelength is 532 nm
  • the objective lens 51 uses NA 0.9, 100 ⁇ Nikon “TU-Plan-Fluor-EPI”.
  • the focused spot of the example is smaller than the focused spot of the comparative example.
  • the focused spot of the example is larger than the focused spot of the comparative example.
  • the focused spot of the example is larger than the focused spot of the comparative example.
  • Embodiment 4 The configuration of the measuring apparatus according to the fourth embodiment will be described with reference to FIG.
  • the condensing lens 15 is replaced with a collimating lens 14 in the configuration of FIG. 9.
  • the condensing lens 15 is removed from the configuration of FIG.
  • the light receiving size of the photodetector 21 is larger than that of the light shielding unit 13. Note that the description common to the first to third embodiments is omitted as appropriate.
  • a light shielding portion 13 is disposed between the holding member 12 and the collimating lens 14.
  • a collimating lens 14 is disposed between the light shielding unit 13 and the photodetector 21.
  • Scattered light L ⁇ b> 2 from the gold nanoparticles 11 passes through the outside of the light shielding unit 13 and enters the collimating lens 14.
  • the collimating lens 14 refracts the scattered light L2 into a parallel light beam.
  • the scattered light L2 refracted by the collimator lens 14 is detected by the photodetector 21. The above effect can also be obtained by this configuration.
  • the light shielding portion 13 is arranged between the holding member 12 and the collimating lens 14, but the arrangement of the light shielding portion 13 is not particularly limited.
  • the arrangement of the light shielding portions 13 can be changed as appropriate.
  • FIG. 20 is a diagram schematically illustrating the configuration of the measurement apparatus.
  • the structure which condenses illumination light L1 on the gold nanoparticle 111 with the objective lens (not shown) is shown.
  • the photodetector 21 is a two-dimensional array detector having a plurality of light receiving elements 211.
  • the holding member 112 has a holding surface 112a that holds the gold nanoparticles 11 and a facing surface 112c that faces the holding surface 112a.
  • the holding member 112 is a transparent parallel plate similar to the holding member 112 shown in FIG. Therefore, the holding surface 112a and the opposing surface 112c are parallel planes.
  • a transparent material having a high refractive index such as glass is used.
  • the holding member 112 is placed directly on the light receiving surface of the photodetector 21.
  • the opposing surface 112c of the holding member 112 and the photodetector 21 are in contact with each other. Therefore, in FIG. 20, the air layer is not interposed between the photodetector 21 and the holding member 112.
  • the same measurement as described above can be performed by summing the detected light amounts of the plurality of light receiving elements 211.
  • the light shielding portion 13 is provided, but the light shielding portion 13 can be omitted.
  • the detection result of the light receiving element 211 on which the illumination light L1 incident on the photodetector 21 without being scattered by the gold nanoparticles 11 may be used. That is, a light receiving element 211 other than the light receiving element 211 on which the illumination light L1 enters may be used.
  • the illumination light L1 is laser light
  • the intensity of the illumination light L1 is extremely higher than the scattered light L2. Therefore, when the illumination light L1 is directly incident on the light receiving element 211, there is a possibility that a phenomenon (smear) in which a saturated charge flows from the CCD pixel flows into the adjacent pixel. In order to avoid the influence of smear, it is preferable to provide the light shielding portion 13.
  • the light shielding part 13 may be between the gold nanoparticle 11 and the photodetector 21.
  • the light shielding unit 13 may be formed on the surface of the holding member 112 on the side of the photodetector 21 or on the surface of the photodetector 21 on the side of the holding member 112.
  • the light shielding unit 13 may be formed directly on the holding member 112 or the photodetector 21, or may be a light shielding plate disposed between the holding member 112 and the photodetector 21.
  • the light shielding unit 13 is in the holding member 112 and may be adjacent to the light receiving surface of the photodetector 21, but a certain distance or more from the gold nanoparticle 11 is required. The distance is a near-field region of light existing around the gold nanoparticle 11 and is a distance of several times the laser wavelength.
  • FIG. 21 shows a polar coordinate system with the gold nanoparticle 11 as the origin.
  • the XY plane is a holding surface 12a of the holding member 12.
  • the induced dipole axis is proportional to the local electric field vector (Equation (6)).
  • the detection value I LFR detected by the photodetectors 21 of Embodiments 1 to 4 shown in FIG. 4 and the like is a value obtained by integrating Is with the direction ( ⁇ , ⁇ ) of scattered light in the polar coordinates shown in FIG. ((Equation 10)).
  • d ⁇ is a spherical surface element.
  • ⁇ 1 is a value determined by the size of the light shielding portion 13.
  • ⁇ 1 is the maximum scattering angle of scattered light that can be shielded by the light shielding unit 13 with respect to the optical axis OX of the objective lens 51 in the scattered light L2 scattered by the gold nanoparticles 11 (see FIG. 19).
  • the maximum light shielding angle of the scattered light L2 is used.
  • the maximum light shielding angle ⁇ 1 is an angle formed by the scattered light incident on the outer edge of the light shielding portion 13 and the optical axis OX.
  • ⁇ 2 is a value determined by the size of the collimating lens 14. As shown in FIG. 19, ⁇ 2 is the maximum scattering of the scattered light L 2 that can be detected by the photodetector 21 with reference to the optical axis OX of the objective lens 51 in the scattered light L 2 scattered by the gold nanoparticles 11. An angle (hereinafter referred to as a maximum detection angle of the scattered light L2). In FIG. 19, the maximum detection angle ⁇ 2 is an angle formed between the scattered light incident on the substantial outer edge of the collimating lens 14 and the optical axis OX. Note that the maximum detection angle ⁇ 2 is a value determined by the size of the photodetector 21 in FIG. 4, a value determined by the size of the condenser lens 15 in FIGS.
  • the value is determined by the collimating lens 14. Further, the shapes of the photodetector 21, the light shielding unit 13, the collimator lens 14, and the condenser lens 15 in a plane perpendicular to the optical axis OX are circular. In addition, when the photodetector 21 etc. are not circular, you may restrict
  • Equation (11) is obtained from Equation (10).
  • Ez 2 is an unknown value, in equation (11), 3 ⁇ (cos ⁇ 1 ⁇ cos 3 ⁇ 1 ) ⁇ (cos ⁇ 2 ⁇ cos 3 ⁇ 2 ) ⁇ Ez 2 is an artifact of the light intensity I (see formulas (5) and (6)) that is a value to be obtained. .
  • the maximum scattering angle with respect to the optical axis OX of the scattered light L2 that can be shielded by the light shielding unit 13 is ⁇ 1 and can be detected by the photodetector 21.
  • the maximum scattering angle with respect to the optical axis OX of the scattered light L2 are the theta 2. It is preferable to set the optical system so as to satisfy the relationship of Expression (13). Thereby, the spatial distribution of light intensity can be measured accurately.
  • Embodiment 6 FIG.
  • the electric field of light is calculated
  • the principle of the measurement method according to the sixth embodiment will be described.
  • the photodetector 21 is a sensor that measures the energy and intensity of light (generally, electromagnetic waves), and is roughly classified into a photoelectric effect type and a thermal effect type.
  • There are also devices that use the sensor to obtain the intensity and energy distribution such as a CCD camera and a CMOS sensor, in which a light receiving portion is two-dimensionally arranged.
  • the relative position of the light receiving unit with the object to be measured can be directly or indirectly changed to measure the position information, light (electromagnetic wave) intensity, and energy distribution. can do.
  • light intensity and energy distribution measuring devices such as cameras, laser microscopes, and beam profilers.
  • light (electromagnetic wave) is a wave propagating in space, and its electric field has a vector quantity.
  • Electric field components Ex and Ey of light traveling in one direction (in the z direction) can be measured as a polarization plane (a ratio of Ex and Ey) by a combination of a polarizer and a photodetector.
  • the electric field to be measured by the present technology is an electric field (Ex, Ey, Ez) due to standing waves generated by interference in a place where traveling waves in two or more directions (angles) overlap.
  • the vector component of the electric field (Ex, Ey, Ez) due to the standing wave generated by the interference is measured at a place where traveling waves in two or more directions (angles) overlap.
  • the place where the electric field is to be measured is the origin.
  • the induced dipole axis is proportional to the local electric field vector (formula (6) above).
  • the light intensity I is represented by the formula (14).
  • the light intensity I at a certain angle is measured by the photodetector 21 having a certain size.
  • the certain angle is expressed by a polar angle ⁇ and an azimuth angle ⁇ (formula (15)).
  • the light intensity I at a certain angle is expressed by the following formula (16).
  • d ⁇ is a spherical surface element.
  • Equation (20) excluding the unknown Ey is obtained.
  • Ex can be obtained.
  • gold nanoparticles 11 that are sufficiently smaller than the wavelength of light are present in the electric field of light, scattered light having a scattering intensity represented by formula (16) is generated.
  • Information on the electric field component of light can be calculated by measuring the light intensity under a plurality of measurement conditions.
  • the measurement under different measurement conditions ⁇ 1 , ⁇ 2 , ⁇ 1 , ⁇ 2 can be performed by changing the three-dimensional angle condition of the scattering angle. That is, by limiting the scattering angle of the scattered light L2 detected by the photodetector 21 at the gold nanoparticles 11 so as to fall within a predetermined angle range, measurement under specific measurement conditions becomes possible.
  • the light detector 21 measures the light intensity while changing the measurement conditions regarding the angle range. Based on the measurement results under a plurality of measurement conditions, the electric field component of light is calculated.
  • a method for changing the measurement conditions ⁇ 1 , ⁇ 2 , ⁇ 1 , ⁇ 2 will be described below.
  • First method As a first method of changing the measurement conditions, there is a method of measuring a plurality of times by changing the position of the photodetector 21. For example, as shown in FIG. 23, the scattered light L2 is detected at the positions of the photodetectors 21a to 21d. In FIG. 23, the size of the detector 21 is assumed to be small. Gold nanoparticles 11 are arranged at positions where traveling waves in two or more directions overlap (shaded portions in FIG. 23). In FIG. 23, the photodetector 21 is arranged at a position where no traveling wave is incident. By moving the single photodetector 21, measurement with different measurement conditions can be performed. Alternatively, a plurality of photodetectors may be arranged at different positions.
  • the personal computer 42 includes a memory, a processor, and the like, and calculates an electric field from the amount of light detected by the photodetector 21 based on equations (16) to (20). For example, the solid angle angle range that can be detected by the photodetector 21 is determined according to the positional relationship between the gold nanoparticles 11 and the photodetector 21.
  • the memory stores measurement conditions ⁇ 1 , ⁇ 2 , ⁇ 1 , ⁇ 2 based on the position of the photodetector 21.
  • the processor calculates the electric field component by executing the program stored in the memory. Since the measurement conditions ⁇ 1 , ⁇ 2 , ⁇ 1 , ⁇ 2 and the detected light intensity I are stored, the electric field component can be calculated from the equations (16) to (20).
  • a photodetector 21 having a plurality of light receiving elements As a second method for changing the measurement conditions, there is a method using a photodetector 21 having a plurality of light receiving elements.
  • a photodetector 21 having a plurality of light receiving elements 211 to 213 is used.
  • a two-dimensional array detector in which pixels are arranged in a two-dimensional array such as a CCD (Charge-Coupled Device) camera or a CMOS (Complementary Metal Oxide Semiconductor) image sensor, is used as the photodetector 21.
  • Each of the light receiving elements 211 to 213 is a pixel.
  • the angle range of the solid angle that can be detected by each light receiving element is determined.
  • the measurement under the first measurement condition is performed with the light receiving element 211
  • the measurement under the second measurement condition is performed with the light receiving element 212
  • the measurement under the third measurement condition is performed with the light receiving element 213.
  • the measurement conditions ⁇ 1 , ⁇ 2 , ⁇ 1 , ⁇ 2 are determined by the arrangement of the plurality of light receiving elements 211 to 213.
  • the measurement conditions are set according to the arrangement of the light receiving elements 211 to 213 of the photodetector 21.
  • the light receiving elements 211 to 213 which are different pixels respectively measure the scattered light, whereby measurement under a plurality of measurement conditions is performed.
  • the amount of light detected by different light receiving elements can be handled as the light intensity I under different measurement conditions.
  • Each pixel can measure the light intensity of a specific angular component.
  • measurement under a plurality of measurement conditions can be completed in one measurement.
  • the photodetector 21 may be a two-dimensional array detector in the configuration of FIG. 4, FIG. 6, FIG. 8, FIG. Then, the amount of light detected at each pixel is input to the personal computer 42 (see FIG. 13).
  • the personal computer 42 includes a memory, a processor, and the like, and calculates an electric field from the detected light amount using equations (16) to (20). For example, measurement conditions ⁇ 1 , ⁇ 2 , ⁇ 1 , ⁇ 2 based on the position of the light receiving element 211 of the photodetector 21 with respect to the gold nanoparticles 11 are set.
  • the processor can calculate the electric field by executing the program stored in the memory.
  • the photodetector 21 when the photodetector 21 is a two-dimensional array detector, a configuration without the light shielding portion 13 may be possible.
  • a light receiving element other than the light receiving element on which the illumination light L1 is incident may be used.
  • the illumination light L1 is laser light
  • the intensity of the illumination light L1 is extremely higher than that of the scattered light L2. Therefore, when the illumination light L1 is directly incident on the light receiving element, there is a possibility that a phenomenon (smear) in which a saturated charge flows from the CCD pixel flows into the adjacent pixel. In order to avoid this influence, it is preferable to have the light shielding portion 13.
  • a third method of changing the measurement conditions there is a method of changing the shape, size, position, etc. of the light-shielding portion 13 arranged in the front stage of the photodetector 21.
  • a plurality of light shielding portions 131 to 134 are arranged on the front side of the photodetector 21.
  • the light shielding parts 131 to 134 are light shielding plates arranged so as to cover a part of the photodetector 21.
  • the light shielding portions 131 to 134 are arranged so as to shield different portions of the photodetector 21.
  • measurement is performed with one of the light shielding portions 131 to 134 removed.
  • the measurement is performed in a state where the light shielding unit 131 is removed from the front of the photodetector 21. That is, under the first measurement condition, measurement is performed with the light shielding portions 132 to 134 covering the photodetector 21.
  • the measurement is performed in a state in which the light shielding unit 132 is removed from the front of the photodetector 21. That is, under the second measurement condition, measurement is performed in a state where the light shielding units 131, 133, and 134 cover the photodetector 21. In this way, the measurement conditions can be changed by removing the light shielding portions 131 to 134 sequentially from the front of the photodetector 21.
  • the photodetector 21 having a single light receiving element can be used.
  • FIG. 26 shows a specific example of the light shielding portion.
  • FIG. 26 is a plan view showing the light shielding unit 13 of four types (TYPE A to TYPE D).
  • the light shielding unit 13 shown in FIG. 26 is a plan view showing the light shielding unit 13 of four types (TYPE A to TYPE D).
  • the light shielding unit 13 illustrated in FIG. 26 is a light shielding plate having a configuration corresponding to FIG. In FIG. 26, the black portion becomes the light shielding region 38 and the white portion becomes the transmission region 39.
  • the scattered light L2 passes through the transmission region 39.
  • the light shielding portion 13 of TYPE A and the light shielding portion 13 of TYPE B have an annular transmission region 39, and the size of the transmission region 39 is different.
  • the radial direction (radial direction) defines ⁇
  • the azimuth direction (circumferential direction) defines ⁇ .
  • the inner diameter of the ring-shaped transmission region 39 defines ⁇ 1 and the outer diameter defines ⁇ 2 .
  • the light shielding portion 13 of TYPE B has a smaller transmission area 39 than the light shielding portion 13 of TYPE A. Therefore, the light shielding portions 13 of TYPE A and TYPE B have different ⁇ 1 and ⁇ 2 . Specifically, ⁇ 1 of the light shielding unit 13 of TYPE A is smaller than ⁇ 1 of the light shielding unit 13 of TYPE B. ⁇ 2 of the light shielding portion 13 of TYPE A is larger than ⁇ 2 of the light shielding portion 13 of TYPE B. Note that the outer shape of the light detector 21, the collimating lens 14, and the condenser lens 15 instead of the light shielding unit 13 may define ⁇ 2 .
  • One of the light shielding portions 13 of TYPE A and TYPE B and one of the light shielding portions 13 of TYPE C and TYPE D are used in combination.
  • the light shielding unit 13 of TYPE B and the light shielding unit 13 of TYPE C are overlapped and arranged at the position of the light shielding unit 13 in FIG.
  • measurement conditions ⁇ 1 , ⁇ 2 , ⁇ 1 , ⁇ 2 based on a three-dimensional angle can be defined.
  • the light shielding unit 13 shown in FIG. 26 can be used in the configurations shown in FIGS. 6, 9 to 12, and 19 without being limited to FIG.
  • the first to third methods can be used in appropriate combination.
  • FIG. 27 is a diagram schematically showing a measuring apparatus for detecting backscattered light.
  • the illumination light L1 that is a parallel light beam enters the half mirror 301.
  • the half mirror 301 transmits a part of the incident light and reflects the rest. Almost half of the illumination light L1 passes through the half mirror 301 and enters the objective lens 301.
  • the objective lens 302 condenses the illumination light L1 on the gold nanoparticles 11. Therefore, traveling waves overlap with the gold nanoparticles 11 from a plurality of directions. In FIG. 27, the holding member that holds the gold nanoparticles 11 is omitted.
  • the scattered light L2 incident on the objective lens 302 becomes a parallel light flux and enters the half mirror 301.
  • Almost half of the scattered light L ⁇ b> 2 is reflected by the half mirror 301 and enters the photodetector 21.
  • the photodetector 21 is a detector composed of a single light receiving element.
  • the light shielding unit 13 is disposed between the photodetector 21 and the half mirror 301.
  • the measurement under different measurement conditions can be performed by changing the shape of the light shielding portion 13.
  • the electric field component in a condensing spot can be calculated
  • FIG. 28 shows another configuration for detecting backscattered light.
  • a two-dimensional array detector is used as the photodetector 21.
  • the half mirror 301 and the objective lens 302 are the same as those in FIG. In FIG. 28, the light shielding unit 13 is not provided.
  • a two-dimensional array detector is used as the photodetector 21. Then, measurement is performed under a plurality of measurement conditions by the second method. That is, the measurement conditions ⁇ 1 , ⁇ 2 , ⁇ 1 , ⁇ 2 corresponding to the position of the light receiving element are stored in the memory of the personal computer 42 in advance. Then, the personal computer 42 calculates the electric field component of light based on the measurement results under a plurality of measurement conditions.
  • this invention includes the appropriate deformation

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Optics & Photonics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)
  • Investigating, Analyzing Materials By Fluorescence Or Luminescence (AREA)
  • Photometry And Measurement Of Optical Pulse Characteristics (AREA)
  • Microscoopes, Condenser (AREA)

Abstract

L'invention concerne un dispositif de mesure, un microscope et un procédé de mesure qui permettent une mesure précise. Un dispositif de mesure, selon un mode de réalisation de la présente invention, est pourvu d'une nanoparticule d'or (11) qui est disposée à l'intérieur ou à proximité du foyer d'un faisceau de lumière et diffuse la lumière de façon à produire une lumière diffusée, d'un détecteur (21) destiné à détecter l'intensité de la lumière diffusée qui a été diffusée à des angles supérieurs à l'angle de convergence maximal auquel le foyer est formé et qui est une lumière diffusée vers l'avant qui a été diffusée vers l'avant à partir de la nanoparticule d'or (11), et d'une unité d'entraînement destinée à modifier la position de la particule par rapport au foyer.
PCT/JP2017/028417 2016-09-12 2017-08-04 Dispositif de mesure, microscope et procédé de mesure WO2018047547A1 (fr)

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CN111551250A (zh) * 2020-07-13 2020-08-18 之江实验室 一种测量光场分布的方法及装置
CN111623871A (zh) * 2020-07-13 2020-09-04 之江实验室 利用纳米微粒测量激光光场相对强度分布的方法和装置
WO2020179049A1 (fr) * 2019-03-07 2020-09-10 カナレ電気株式会社 Dispositif de mesure de profil de faisceau pour lumière laser
CN112284261A (zh) * 2020-10-10 2021-01-29 中国电子科技集团公司第十一研究所 一种激光红外装置光轴偏移量检测***
KR102258886B1 (ko) * 2019-11-28 2021-05-31 재단법인대구경북과학기술원 내시현미경의 수평 분해능 최적화 장치, 최적화 광학 시스템 및 최적화 방법

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WO2020179049A1 (fr) * 2019-03-07 2020-09-10 カナレ電気株式会社 Dispositif de mesure de profil de faisceau pour lumière laser
JPWO2020179049A1 (ja) * 2019-03-07 2021-11-25 カナレ電気株式会社 レーザ光のビームプロファイル測定装置
KR102258886B1 (ko) * 2019-11-28 2021-05-31 재단법인대구경북과학기술원 내시현미경의 수평 분해능 최적화 장치, 최적화 광학 시스템 및 최적화 방법
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CN111623871A (zh) * 2020-07-13 2020-09-04 之江实验室 利用纳米微粒测量激光光场相对强度分布的方法和装置
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CN112284261A (zh) * 2020-10-10 2021-01-29 中国电子科技集团公司第十一研究所 一种激光红外装置光轴偏移量检测***

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