JP2016075810A - Light irradiation device and light irradiation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light irradiation device and a light irradiation method capable of simply realizing a structure for moving an irradiation region of vessel light.SOLUTION: A vessel light irradiation device 1A includes: a laser light source 10 for outputting modulated light 1; a SLM 20 for modulating the modulated light L1 from the laser light source 10 and outputting modulation light L2; and an object lens 30 for converting the modulation light L2 from the SLM 20 into vessel light Lb so as to be irradiated on an object B. The object lens 30 is a Fourier transformation lens. A phase pattern presented to the SLM 20 includes: a first pattern for focusing the modulation light L2 on a pupil plane 31 of the object lens 30 by having a rotation symmetrical phase distribution around a certain reference point; and a second pattern superposed on the first pattern, constant in phase value in a radiation direction extending from the reference point, and having a continuous phase change in the peripheral direction with the reference point as a center.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a light irradiation apparatus and a light irradiation method.

  Non-Patent Document 1 describes a technique related to Bessel light illumination. In the apparatus described in Non-Patent Document 1, after the Bessel light is generated by the axicon lens, the Bessel light is Fourier-transformed using another lens to generate ring light. The generated ring light is subjected to complex amplitude modulation by a spatial light modulator (SLM) and is subjected to Fourier transform again by a lens to become Bessel light. Then, the position of the Bessel light illumination is arbitrarily changed by changing the modulation pattern of the complex amplitude modulation in the SLM.

T. Cizmar et al., “Generation of multiple Bessel beams for a biophotonics workstation”, OPTICS EXPRESS14024, Vol. 16, No. 18, 1 September 2008

  In recent years, using an SLM in an optical microscope to control illumination light applied to an object has been studied. For example, when the illumination light is converted into Bessel light using an SLM, application to a laser processing apparatus or a fluorescence microscopic measurement apparatus is conceivable. In addition, since Bessel illumination is light that consists of only an arbitrary angle component, it can be used in systems such as total reflection illumination systems, Brewster's angle microscopes, or ellipsometry systems that measure based on angular dependence. Applications are also possible.

  In order to generate Bessel light using the SLM, illumination light may be collected on the pupil plane of the objective lens. For example, a phase pattern such as a toroidal lens pattern is presented on the SLM, and illumination light is condensed in a ring shape on the pupil plane, whereby spot-like (dotted) Bessel light is generated in the objective lens. However, in order to move such an irradiation area of the spot-like Bessel light, it is necessary to move the optical system including the objective lens, which increases the size and complexity of the apparatus configuration. In the method described in Non-Patent Document 1, the position of the Bessel light illumination is changed by complex amplitude modulation of the SLM, but it is necessary to generate Bessel light using an axicon lens before the modulation. Therefore, it is impossible to solve problems such as an increase in size and complexity of the apparatus. In addition, since an axicon lens is provided in the optical system, a mechanical switching mechanism of the optical system is required to realize different types of illumination light from the Bessel light illumination with the same device. .

  The present invention has been made in view of such problems, and an object thereof is to provide a light irradiation apparatus and a light irradiation method capable of easily realizing a configuration for moving the irradiation region of the Bessel light. And

  A light irradiation apparatus according to the present invention is an apparatus for irradiating an object with Bessel light, a light source that outputs light that is modulated light, and a phase modulation type that modulates light from the light source and outputs modulated light. A spatial light modulator, and an objective lens that converts the modulated light from the spatial light modulator into Bessel light and irradiates the object, the objective lens being a Fourier transform lens, and a phase presented to the spatial light modulator The pattern has a phase distribution that is rotationally symmetric about a certain point, so that the modulated light is focused on the pupil plane of the objective lens, and the phase value is superimposed on the first pattern and has a phase value in the radial direction extending from the point. And a second pattern having a constant phase change in the circumferential direction centered on the point.

  The light irradiation method according to the present invention is a method of irradiating an object with Bessel light, which modulates light output from a light source using a phase modulation spatial light modulator and outputs modulated light, The phase pattern displayed on the spatial light modulator is rotationally symmetric around a certain reference point. Each phase pattern is converted into Bessel light using an objective lens, which is a Fourier transform lens, and irradiated onto an object. A first pattern for focusing the modulated light on the pupil plane of the objective lens by having a stable phase distribution, and a phase value that is superimposed on the first pattern and that is constant in the radial direction extending from the reference point, and centered on the reference point And a second pattern having a continuous phase change in the circumferential direction.

  In these light irradiation apparatuses and light irradiation methods, the second pattern is superimposed on the first pattern for generating the Bessel light in the phase pattern. The second pattern has a constant phase value in the radial direction extending from the point, and has a continuous phase change in the circumferential direction around the point. The present inventor has found that the irradiation region of the Bessel light moves in the direction based on the phase change in the circumferential direction by superimposing such a second pattern. As described above, according to the above-described Bessel light irradiation apparatus and the Bessel light irradiation method, the configuration for moving the irradiation area of the Bessel light is realized by the spatial light modulator and the objective lens necessary for generating the Bessel light. can do. Therefore, the configuration for moving the irradiation area of the Bessel light can be easily realized.

  In addition, the light irradiation apparatus and the light irradiation method described above may be characterized in that the first pattern is a toroidal pattern. Thereby, Bessel light can be suitably generated via the objective lens which is a Fourier transform lens.

  In the light irradiation apparatus and the light irradiation method, the phase pattern includes a plurality of reference points, and in the second pattern, the phase change centered on each reference point is individually set for each reference point. This may be a feature. As a result, it is possible to simultaneously irradiate the plurality of positions with the Bessel light, and to move the Bessel light at each position in independent arbitrary directions.

  According to the light irradiation apparatus and the light irradiation method of the present invention, a configuration for moving the irradiation region of the Bessel light can be easily realized.

It is a figure which shows schematically the structure of the Bessel light irradiation apparatus which concerns on embodiment of this invention. (A) It is a figure which expands and shows the vicinity of an objective lens and a target object. (B) It is the figure which looked at the pupil surface from the optical axis direction. It is a figure which shows the example of the 1st pattern shown to SLM by the control part. It is a figure which shows the example of the 2nd pattern shown to SLM by a control part. (A), (b) It is a graph explaining the phase distribution of a 2nd pattern in more detail. FIG. 5 is a diagram showing a phase pattern in which the first pattern shown in FIG. 3 and the second pattern shown in FIG. 4 are superimposed. It is a figure for demonstrating the relationship between various 2nd patterns and the moving direction of an irradiation area | region. (A) Represents the second pattern. (B) A phase pattern in which the second pattern of (a) and the first pattern of FIG. 3 are superimposed is shown. (C) conceptually shows a positional relationship between an irradiation region in a state where only the first pattern of FIG. 3 is presented and an irradiation region in a state where the phase pattern shown in (b) is presented. It is a figure for demonstrating the relationship between various 2nd patterns and the moving direction of an irradiation area | region. (A) Represents the second pattern. (B) A phase pattern in which the second pattern of (a) and the first pattern of FIG. 3 are superimposed is shown. (C) conceptually shows a positional relationship between an irradiation region in a state where only the first pattern of FIG. 3 is presented and an irradiation region in a state where the phase pattern shown in (b) is presented. It is a figure for demonstrating the relationship between various 2nd patterns and the moving direction of an irradiation area | region. (A) Represents the second pattern. (B) A phase pattern in which the second pattern of (a) and the first pattern of FIG. 3 are superimposed is shown. (C) conceptually shows a positional relationship between an irradiation region in a state where only the first pattern of FIG. 3 is presented and an irradiation region in a state where the phase pattern shown in (b) is presented. It is a figure which shows a 1st modification. (A) A 1st pattern is shown. (B) The irradiation area of Bessel light is shown. It is a figure which shows a 1st modification. (A) A phase pattern in which a first pattern and a second pattern are superimposed is shown. (B) The irradiation area of Bessel light is shown. It is a figure which shows a 2nd modification. It is a perspective view which shows the specific example of the shape of a high refractive index medium. It is a figure which expands and shows a part of structure of the total reflection illumination system as a comparative example. It is a figure which shows schematically the structure of the SLM microscope which concerns on a comparative example. It is a figure which shows the structure of a SLM microscope roughly.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a light irradiation apparatus and a light irradiation method according to the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a diagram schematically showing a configuration of a Bessel light irradiation apparatus 1A according to an embodiment of the present invention. The vessel light irradiation device 1A irradiates the object B with the vessel light Lb. As shown in FIG. 1, the Bessel light irradiation apparatus 1 </ b> A according to the present embodiment includes a laser light source 10, a collimating lens 11, a spatial light modulator (SLM) 20, and an objective lens 30.

  The laser light source 10 outputs the modulated light L1 and provides it to the SLM 20. The modulated light L1 is laser light, and the wavelength is a wavelength included in a range of 200 nm to 2000 nm, for example. However, the modulated light L1 is not limited to laser light, but may be coherent light. The modulated light L1 may be pulsed light or continuous wave light (CW (Continuous Wave) light). The collimating lens 11 is disposed on the optical axis of the modulated light L 1, and the modulated light L 1 emitted from the laser light source 10 is collimated by the collimating lens 11.

  The SLM 20 is a phase modulation type SLM optically coupled to the laser light source 10. The SLM 20 phase-modulates the modulated light L1 from the laser light source 10 and outputs a modulated light L2. As will be described later, the SLM 20 presents a phase pattern in which a first pattern for generating Bessel light and a second pattern for moving the irradiation region of the Bessel light are superimposed. A control unit 21 is electrically connected to the SLM 20, and a signal including such a phase pattern is provided from the control unit 21 to the SLM 20.

  The objective lens 30 is disposed on the optical axis between the SLM 20 and the object B. The objective lens 30 is a Fourier transform lens, converts the modulated light L2 from the SLM 20 into the vessel light Lb, and irradiates the object B with the vessel light Lb. At this time, the Bessel light Lb has a dot shape (spot shape). In the figure, the pupil plane 31 of the objective lens 30 is shown.

  Here, FIG. 2A is an enlarged view showing the vicinity of the objective lens 30 and the object B. FIG. As shown in FIG. 2A, in the present embodiment, the modulated light L2 is focused on the pupil plane 31 of the objective lens 30. FIG. 2B is a diagram of the pupil plane 31 viewed from the optical axis direction. On the pupil plane 31, the modulated light L2 is focused in an annular shape (ring shape). The modulated light L2 enters the objective lens 30 after passing through the pupil plane 31. In the objective lens 30, the modulated light L2 is Fourier-transformed into Bessel light Lb, and is focused by the objective lens 30 and directed to the spot-shaped irradiation region P.

  FIG. 3 is a diagram illustrating an example of the first pattern presented to the SLM 20 by the control unit 21, where the phase value is represented by color shading, where the darker region has a smaller phase value and the lighter region has a phase value. high. The first pattern has a rotationally symmetric phase distribution around a certain reference point C, thereby focusing the modulated light L2 on the pupil plane 31 of the objective lens 30 as shown in FIG. FIG. 3 shows a so-called toroidal pattern as an example of such a rotationally symmetric phase distribution. Due to the toroidal pattern, the modulated light L2 can be condensed on the pupil surface 31 in a ring shape.

  FIG. 4 is a diagram illustrating an example of the second pattern presented to the SLM 20 by the control unit 21, and similarly to FIG. 3, the phase value is represented by color shading. As shown in FIG. 4, the second pattern has a constant phase value in the radial direction (radial direction, arrow A4 in the figure) extending from the reference point C, and the circumferential direction (in the figure, centering on the reference point C). In the arrow A5), there is a continuous phase change. Note that the reference point C coincides with the reference point C shown in FIG.

  FIGS. 5A and 5B are graphs for explaining the phase distribution of the second pattern in more detail. FIG. 5A shows a phase change on a certain straight line passing through the reference point C in FIG. 4, and FIG. 5B shows a phase on a certain circle centered on the reference point C in FIG. It shows a change. The horizontal axis in FIG. 5A represents the distance from the reference point C, and the horizontal axis in FIG. 5B represents the angle around the reference point C (deflection angle α). As shown in FIG. 5A, the second pattern has a constant phase value in the radial direction extending from the reference point C. Further, as shown in FIG. 5B, the second pattern has a continuous phase change (for example, a plurality of sine waves having different phases superimposed on each other in the circumferential direction around the reference point C as a function of the radiation angle). One). Note that the start point and end point of the phase change are smoothly coupled.

  Here, the continuous phase change means that each phase value is located on a continuous function such as a trigonometric function when the phase value of each pixel arranged in the circumferential direction is used as a function of an angle. However, when the upper limit of the display phase range of the SLM 20 is reached, it is necessary to start from the lower limit (so-called phase folding) in the next pixel. Such discontinuity due to phase folding is assumed to be included in the continuous phase change in this embodiment.

  FIG. 6 is a diagram showing a phase pattern in which the first pattern shown in FIG. 3 and the second pattern shown in FIG. 4 are superimposed. When the phase pattern shown in FIG. 6 is presented to the SLM 20, the irradiation region P (see FIG. 2) of the Bessel light Lb moves in a predetermined direction by a predetermined distance.

7-9 is a figure for demonstrating the relationship between the various 2nd patterns and the moving direction of the irradiation area | region P. FIG. 7-9, (a) represents a 2nd pattern, (b) shows the phase pattern on which the 2nd pattern of (a) and the 1st pattern (toroidal pattern) of FIG. 3 were superimposed. (C) conceptually shows the positional relationship between the irradiation region P1 in the state where only the first pattern (toroidal pattern) of FIG. 3 is presented and the irradiation region P2 in the state where the phase pattern shown in (b) is presented. FIG. In the second pattern shown in FIG. 7A, the phase value is maximum when the declination α is 90 °, and the phase value is minimum when the declination α is 270 °. In this case, as shown in FIG. 7C, the moving direction of the irradiation region is a radial direction with a declination of 90 °. In the second pattern shown in FIG. 8A, the phase value is maximum when the declination α is 0 °, and the phase value is minimum when the declination α is 180 °. In this case, as shown in FIG. 8C, the moving direction of the irradiation region is a radial direction with a declination of 0 °. In the second pattern shown in FIG. 9A, the phase value is maximum when the declination α is 45 °, and the phase value is minimum when the declination α is 225 °. In this case, as shown in FIG. 9C, the moving direction of the irradiation region is a radial direction with a declination of 45 °. According to these examples, when the phase value is the maximum at a certain declination α _{1 and} the phase value is the minimum at the declination (α ₁ + 180 °), the irradiation region is in the radial direction of the declination α ₁ . You can see that

  In addition, the light irradiation method of this embodiment is a method of irradiating the object B with the vessel light Lb by using the vessel light irradiation apparatus 1A. This light irradiation method uses a phase modulation type SLM 20 to modulate the modulated light L1 and output the modulated light L2, and uses the objective lens 30 that is a Fourier transform lens to convert the modulated light L2 into Bessel light. Converting to Lb and irradiating the object B. The phase pattern presented to the SLM 20 is superimposed on the first pattern and the first pattern for focusing the modulated light L2 on the pupil plane of the objective lens 30 by having a rotationally symmetric phase distribution around a certain reference point C. And a second pattern having a constant phase value in the radial direction extending from the reference point C and having a continuous phase change in the circumferential direction around the reference point C.

  The effects obtained by the Bessel light irradiation apparatus 1A and the light irradiation method of the present embodiment described above will be described. In the Bessel light irradiation apparatus 1A and the light irradiation method, the second pattern is superimposed on the first pattern for generating the Bessel light Lb in the phase pattern presented to the SLM 20. Since the first pattern has a rotationally symmetric phase distribution around the reference point C, the modulated light L2 is focused on the pupil plane 31 of the objective lens 30. Therefore, since the Bessel light Lb can be generated without using optical elements such as an axicon lens and a Fourier transform lens, the configuration can be simplified.

  Further, as illustrated in FIGS. 4 and 7A to 9A, the second pattern has a constant phase value in the radial direction (radial direction) extending from the reference point C. It has a continuous phase change in the central circumferential direction. The inventor has found that the irradiation region of the Bessel light Lb moves in the direction based on the phase change in the circumferential direction by superimposing such a second pattern. According to the vessel light irradiation apparatus 1A and the light irradiation method of the present embodiment, the SLM 20 and the objective lens 30 that are inherently necessary for generating the vessel light Lb are configured to move the irradiation region of the vessel light Lb. Can be realized. Accordingly, the irradiation region of the Bessel light Lb can be moved only by electronic control without depending on the mechanical operation, and a configuration for moving the irradiation region of the Bessel light Lb can be easily realized.

  Further, as in the present embodiment, the first pattern may be a toroidal pattern. Thereby, Bessel light Lb can be generated suitably. In this embodiment, the toroidal pattern is exemplified as the first pattern. However, the first pattern generates a pattern having a rotationally symmetric phase distribution around the reference point C, in other words, a point-symmetric light intensity distribution. Any pattern that has such a phase pattern and that becomes a point in actual terms when Fourier-transformed may be used. Examples of such a pattern include a Fresnel lens pattern and a toroidal-Fresnel lens pattern. Further, the phase pattern presented to the SLM 20 may be a pattern in which another pattern is superimposed on a pattern in which the first pattern and the second pattern are superimposed.

(First modification)
10 and 11 are diagrams showing a first modification of the embodiment. FIG. 10A shows the first pattern, and FIG. 10B shows the irradiation region P1 of the Bessel light Lb realized by the first pattern. FIG. 11A shows a phase pattern in which the first pattern and the second pattern are superimposed. FIG. 11B shows the irradiation region P2 of the Bessel light Lb realized by this phase pattern and the irradiation. The positional relationship with the region P1 is shown.

  As shown in FIG. 10A, the first pattern of the present modification includes a plurality of reference points C, and has a rotationally symmetric phase distribution (for example, a toroidal pattern) around each reference point C. When the phase pattern presented on the SLM 20 includes only this first pattern, the plurality of irradiation regions P1 of the Bessel light Lb are positions corresponding to the respective reference points C as shown in FIG.

  On the other hand, the second pattern also includes a plurality of reference points C that respectively match the plurality of reference points C of the first pattern. The phase change around each reference point C is set individually for each reference point C (see FIG. 11A). As a result, as shown in FIG. 11B, it is possible to simultaneously irradiate the plurality of irradiation regions P2 with the Bessel light Lb and to move the irradiation regions P2 in arbitrary independent directions.

(Second modification)
FIG. 12 is a diagram illustrating a second modification of the embodiment. The Bessel light irradiation apparatus 1B of the present modification further includes a high refractive index medium (solid immersion lens) 40 in addition to the configuration of the Bessel light irradiation apparatus 1A of the above-described embodiment. The high refractive index medium 40 has a conical side surface 41 and a flat bottom surface 42. The high refractive index medium 40 is disposed between the objective lens 30 and the object B so that the central axis thereof coincides with the optical axis 32 of the objective lens 30. The side surface 41 is perpendicular to the traveling direction of the Bessel light Lb (arrow A3 in the figure), and the angle θ formed between the traveling direction A3 of the Bessel light Lb and the normal line of the bottom surface 42 is a medium (for example, It is larger than the total reflection critical angle defined by the refractive index difference between the object B) and the high refractive index medium 40. Accordingly, the Bessel light Lb incident from the side surface 41 and reaching the bottom surface 42 is totally reflected at the bottom surface 42. By arranging the high refractive index medium 40 between the objective lens 30 and the object B as in this modification, the Bessel light irradiation apparatus 1B can be applied as a total reflection illumination apparatus.

  FIG. 13 is a perspective view showing a specific example of the shape of the high refractive index medium 40. The high refractive index medium 40 may have a truncated cone shape (trapezoid shape having a linear slope) as shown in FIG. 13A, for example, and has a cone shape as shown in FIG. You may have.

  Here, FIG. 14 is an enlarged view showing a part of the configuration of the total reflection illumination system 100 as a comparative example. The total reflection illumination system 100 includes a high refractive index medium 102. Then, the light Lc is incident on the focal plane from the direction inclined with respect to the central axis of the high refractive index medium 102 while being condensed. Thus, since the light Lc is incident while being condensed (that is, there are a plurality of incident angles), the surface 102a of the high refractive index medium 102 is hemispherical. The light Lc is totally reflected at the bottom surface 102 b of the high refractive index medium 102.

  In the total reflection illumination device including the Bessel light irradiation device 1B according to this modification, the Bessel light Lb is generated by the objective lens 30, so the incident angle is constant. Therefore, as described above, the high refractive index medium 40 preferably has a linear slope. Further, since the incident angle is constant, unlike the total reflection illumination system 100, the incident angle remains unchanged even when the irradiation area is changed. Therefore, the irradiation area moving method as in the above embodiment can be suitably applied. In addition, according to the total reflection illumination device including the Bessel light irradiation device 1B of this modification, for example, when used in a microscope, the spatial resolution can be improved by about 13% compared to the total reflection illumination system 100. .

  Further, according to the total reflection illumination device including the Bessel light irradiation device 1B of the present modification, the half width of the irradiation region can be reduced as compared with the total reflection illumination system 100. For example, when the refractive index of the high refractive index medium 40 is 2.4, the refractive index outside the bottom surface 42 is 1.33, the polarized light is radial polarized light, the incident angle θ of the Bessel light Lb is 60 °, and the wavelength is 405 nm, irradiation is performed. The half width of the region is about 88 nm. On the other hand, in the total reflection illumination system 100 shown in FIG. 14, under the same conditions (however, the incident angle is 40 ° to 60 °), the half width of the irradiation region is about 100 nm. Thus, the contribution to the resolution by the combination of the Bessel light irradiation apparatus of the above embodiment and the high refractive index medium 40 is about 1.13 times.

  Here, FIG. 15 is a diagram schematically illustrating a configuration of the SLM microscope 200 according to the comparative example. As shown in FIG. 15, the SLM microscope 200 includes a laser light source 202, an acousto-optic modulator (AOM) 204, a pinhole 206, lenses 208 and 210, a reflector 212, an SLM 214, and a conjugate lens system. A pair of lenses 216 and 218, a dichroic mirror 220, an objective lens 222, and oil immersion oil 224. In the figure, a pupil plane 222a of the objective lens 222 and a plane 222b conjugate to the pupil plane 222a are shown. The SLM 214 is disposed on the surface 222b.

  The light emitted from the laser light source 202 passes through the AOM 204, the pinhole 206, the lenses 208 and 210, and reaches the reflecting mirror 212. Then, this light is folded back by the reflecting mirror 212 and reaches the SLM 214. In the SLM 214, aberration correction, hologram projection for generating spot-like light, intensity modulation, and the like are performed. The modulated light reaches the dichroic mirror 220 through the pair of lenses 216 and 218 and is directed to the objective lens 222 by the dichroic mirror 220. This light is collected by the objective lens 222 and irradiated on the surface of the object B through the oil immersion oil 224.

  In the SLM microscope 200, the spatial intensity distribution is modulated by presenting the phase diffraction grating to the SLM 214. In other words, spatial intensity modulation is performed by partially losing intensity. However, in such a system, there is a problem that intensity loss becomes large when spatially significant intensity modulation is performed.

  In order to avoid the above problem, for example, in the SLM microscope 200A shown in FIG. 16, the SLM 214 is arranged away from the surface 222b. With such a configuration, switching between total reflection and non-total reflection is facilitated, and energy loss can be reduced. Further, it is possible to switch between surface illumination, structured illumination, and spot illumination (Bessel illumination). Furthermore, it is possible to easily add a function of changing the polarization operation and illumination intensity. However, when the SLM 214 is arranged away from the surface 222b as described above, it is difficult to move (scan) the irradiation region simply by causing the SLM 214 to present the phase pattern for Bessel illumination.

  The Bessel light irradiation apparatus 1B according to this modification can solve such a problem. If the Bessel light irradiation apparatus 1B of this modification is applied to the SLM microscope 200A, a TIRF (Total Internal Reflection Fluorescence) microscope, a Brewster microscope, or an ellipsometry with high resolution can be easily realized.

  DESCRIPTION OF SYMBOLS 1A, 1B ... Bessel light irradiation apparatus, 10 ... Laser light source, 11 ... Collimating lens, 20 ... SLM, 21 ... Control part, 30 ... Objective lens, 31 ... Pupil plane, 32 ... Optical axis, 40 ... High refractive index medium, DESCRIPTION OF SYMBOLS 41 ... Side surface, 42 ... Bottom surface, 100 ... Total reflection illumination system, 102 ... High refractive index medium, 102a ... Surface, 102b ... Bottom surface, 200, 200A ... SLM microscope, 202 ... Laser light source, 206 ... Pinhole, 208 ... Lens , 212 ... reflecting mirror, 216 ... lens, 220 ... dichroic mirror, 222 ... objective lens, 222a ... pupil surface, 222b ... plane, 224 ... oil-immersed oil, B ... target, C ... reference point, L1 ... modulated light , L2 ... modulated light, Lb ... Bessel light, P, P1, P2 ... irradiation region.

Claims (6)

An apparatus for irradiating an object with Bessel light,
A light source that outputs light;
A phase modulation type spatial light modulator that modulates the light and outputs modulated light; and
An objective lens for converting the modulated light into the Bessel light and irradiating the object;
With
The objective lens is a Fourier transform lens;
The phase pattern presented to the spatial light modulator is
A first pattern for focusing the modulated light on the pupil plane of the objective lens by having a rotationally symmetric phase distribution around a reference point;
A second pattern superimposed on the first pattern, having a constant phase value in a radial direction extending from the reference point, and having a continuous phase change in a circumferential direction centered on the reference point;
A light irradiation device.   The light irradiation apparatus according to claim 1, wherein the first pattern is a toroidal pattern. The phase pattern includes a plurality of the reference points;
The light irradiation apparatus according to claim 1, wherein in the second pattern, the phase change centered on each reference point is set individually for each reference point. A method of irradiating an object with Bessel light,
Using a phase modulation type spatial light modulator to modulate light and output modulated light;
Using an objective lens that is a Fourier transform lens, converting the modulated light into the Bessel light and irradiating the object,
The phase pattern presented to the spatial light modulator is
A first pattern for focusing the modulated light on the pupil plane of the objective lens by having a rotationally symmetric phase distribution around a reference point;
A second pattern superimposed on the first pattern, having a constant phase value in a radial direction extending from the reference point, and having a continuous phase change in a circumferential direction centered on the reference point;
A light irradiation method.   The light irradiation method according to claim 4, wherein the first pattern is a toroidal pattern. The phase pattern includes a plurality of the reference points;
6. The light irradiation method according to claim 4, wherein in the second pattern, the phase change centered on each reference point is set individually for each reference point.