Scanning microscope

Abstract

A scanning optical system (SL) of this scanning microscope comprises a plurality of lens components and has positive refractive power as a whole, each lens component comprising one cemented lens composed of a plurality of lenses cemented to each other, or one lens. The scanning optical system satisfies the following conditional expression.　0.007 < Σ(nd×tc / νd) / LA < 0.021 where Σ(nd×tc / νd) is the sum total of nd×tc / νd of lenses of the plurality of lens components when a refractive index for the d line of a lens constituting the plurality of lens components is denoted by nd, the center thickness of the lens is denoted by tc, and the Abbe's number of the lens is denoted by νd, and LA is the distance on an optical axis from a lens surface on the scanning mechanism side of a lens component closest to a scanning mechanism to a lens surface on the objective optical system side of a lens component closest to an objective optical system.

Description

Technical Field

[0001] The present invention relates to a scanning microscope.

Background Art

[0002] Conventionally, a scanning microscope equipped with a scanning optical system that guides light from a scanning mechanism to an objective optical system has been known (see, for example, Patent Document 1). In such a scanning microscope, it has been difficult to obtain a bright image.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] The scanning microscope according to the present invention includes a scanning mechanism that scans a sample with light from a light source, an objective optical system that condenses the light from the scanning mechanism onto the sample, and a scanning optical system provided between the scanning mechanism and the objective optical system that guides the light from the scanning mechanism to the objective optical system. The scanning optical system is composed of a plurality of lens components arranged along the optical axis and has a positive refractive power as a whole. The lens component is composed of a single cemented lens formed by a plurality of lenses joined to each other or a single lens. The lens surface on the scanning mechanism side in the lens component closest to the scanning mechanism among the plurality of lens components is concave, and the lens surface on the objective optical system side in the lens component closest to the objective optical system among the plurality of lens components is concave, and satisfies the following conditional expression and 0.007 < Σ(nd × tc / νd) / LA < 0.021 However, Σ(nd × tc / νd): When the refractive index for the d-line of the lens constituting the plurality of lens components is nd, the center thickness of the lens is tc, and the Abbe number of the lens is νd, the sum of nd × tc / νd of the lens in the plurality of lens components LA: The distance on the optical axis from the lens surface on the scanning mechanism side in the lens component closest to the scanning mechanism to the lens surface on the objective optical system side in the lens component closest to the objective optical system Further, some of the plurality of lens components each consist of one positive lens and satisfy the following conditional expressions 。 νdP < 38 0.651 < θgFP+(0.001682×νdP) where νdP: Abbe number of the positive lens θgFP: partial dispersion ratio of the positive lens, which is defined by the following formula when the refractive index for the g-line of the positive lens is ngP, the refractive index for the F-line of the positive lens is nFP, and the refractive index for the C-line of the positive lens is nCP θgFP=(ngP - nFP) / (nFP - nCP)

Brief Description of the Drawings

[0005]

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Mode for Carrying Out the Invention

[0006] Hereinafter, a scanning microscope equipped with the scanning optical system according to the present embodiment will be described. First, as an example of the scanning microscope according to the present embodiment, a scanning confocal microscope 1 will be described with reference to FIG. 1. The scanning confocal microscope 1 includes an excitation light introduction unit 2 that guides the illumination laser light from the light source unit 6 onto the sample SA, a scanning device 3 that deflects the laser light focused on the sample SA and scans it on the sample SA, a light detection device 5 that detects the light intensity signal from the sample SA corresponding to multiphoton excitation, and a condenser optical system 4 that guides the light from the sample SA to the light detection device 5.

[0007] The light source unit 6 may be provided in the scanning confocal microscope 1 or may be provided separately from the scanning confocal microscope 1. The light source unit 6 is composed of a laser light source (not shown), a beam diameter adjustment mechanism (not shown), and the like. The light source unit 6 oscillates pulsed laser light as the illumination laser light.

[0008] The excitation light introduction unit 2 includes a collimator lens 21, a dichroic mirror 22, and an objective optical system 25 composed of a second objective lens 23 and an objective lens 24. The collimator lens 21 and the dichroic mirror 22 are disposed inside a microscope housing portion 12 provided above a lens barrel portion 11 in the microscope body 10. The light source unit 6 and the microscope housing portion 12 are connected by an optical fiber 69 using connectors C3 and C4. The collimator lens 21 converts the laser light (light beam) oscillated from the light source unit 6 into parallel light. The dichroic mirror 22 reflects the laser light from the collimator lens 21 toward the sample SA. The objective optical system 25 condenses the laser light reflected by the dichroic mirror 22 onto the sample SA by the second objective lens 23 and the objective lens 24. The second objective lens 23 is disposed inside the lens barrel portion 11 in the microscope body 10. The objective lens 24 is attached to the lower portion of the lens barrel portion 11.

[0009] The scanning device 3 includes a scanning mechanism (scanner) 31 and a scanning optical system 32. The scanning device 3 is disposed between the dichroic mirror 22 and the second objective lens 23 inside the microscope housing portion 12. The scanning mechanism (scanner) 31 includes, for example, a galvanometer mirror (not shown) or a resonant mirror (not shown). The scanning mechanism (scanner) 31 deflects the incident laser light. That is, the scanning mechanism (scanner) 31 deflects the laser light condensed on the sample SA to scan the sample SA. The scanning optical system 32 is an optical system provided between the scanning mechanism (scanner) 31 and the second objective lens 23. Also, the scanning optical system 32 is an optical system in which the focal position of the scanning optical system 32 is located on an imaging surface 13 (also referred to as a primary imaging surface) conjugate with the sample SA (scanning surface of the sample SA).

[0010] The light collecting optical system 4 includes an objective lens 24 and a second objective lens 23 that constitute the objective optical system 25, a total reflection mirror 41, and a light collecting lens 42. The total reflection mirror 41 and the light collecting lens 42 are disposed above the dichroic mirror 22 inside the microscope housing 12. The total reflection mirror 41 reflects the fluorescence from the sample SA that has passed through the objective lens 24 and the second objective lens 23. The light collecting lens 42 collects the fluorescence reflected by the total reflection mirror 41.

[0011] The light detection device 5 includes an optical fiber 53 and a detection unit 55. The optical fiber 53 is connected to the microscope housing 12 and the detection unit 55 using connectors C1 and C2. The light (fluorescence) collected by the light collecting lens 42 is incident on the optical fiber 53. The detection unit 55 detects the light (fluorescence) that has passed through the optical fiber 53. A processing unit 57 is electrically connected to the detection unit 55 via a cable 56. Image processing (of the sample SA) is performed based on the detection signal detected by the detection unit 55 by the processing unit 57, and the observation image of the sample SA obtained by the image processing of the processing unit 57 is displayed on a monitor (not shown).

[0012] Note that the laser light from the scanning device 3 is once focused on the imaging plane 13 (primary imaging plane), and then is configured to be focused onto the sample SA again by the second objective lens 23 and the objective lens 24 of the objective optical system 25. That is, the scanning plane of the sample SA, the imaging plane 13, and the light incident surface with respect to the optical fiber 53 are in a conjugate relationship with each other. Therefore, by being configured to be focused onto the sample SA by the second objective lens 23 and the objective lens 24, it becomes possible to make the fluorescence passing through the objective lens 24 reach the detection unit 55 without leakage among the fluorescence generated by multi-photon excitation. Also, in the case of a multi-photon excitation type confocal microscope, multi-photon excitation occurs only in a minute region near the focal point of the objective lens 24. Therefore, it is possible to obtain an image near the focal plane of the objective lens 24 in the same manner as a normal confocal microscope without using a light shielding plate 52 having a pinhole (refer to the two-dot chain line in FIG. 1).

[0013] As the scanning optical system 32, it is possible to use the scanning optical system SL described hereinafter. Therefore, the scanning optical system SL used in the scanning microscope (scanning confocal microscope 1) according to the present embodiment will be described. The scanning optical system SL according to the present embodiment is composed of a plurality of lens components arranged along the optical axis, for example, like the scanning optical system SL(1) shown in FIG. 2, and has a positive refractive power as a whole. Each lens component is composed of a single cemented lens composed of a plurality of lenses cemented to each other, or a single lens. Among the plurality of lens components, the lens surface on the scanning mechanism side in the lens component closest to the scanning mechanism 31 (the pupil conjugate surface P conjugate to the pupil surface of the objective optical system 25) is concave. Among the plurality of lens components, the lens surface on the objective optical system side in the lens component closest to the objective optical system 25 (image plane I) is concave.

[0014] Under the above configuration, the scanning optical system SL according to the present embodiment satisfies the following conditional expression (1). 0.007 < Σ(nd × tc / νd) / LA < 0.021 ···(1) However, Σ(nd × tc / νd): When the refractive index for the d-line of the lens constituting the plurality of lens components is nd, the center thickness of the lens is tc, and the Abbe number of the lens is νd, the sum of nd × tc / νd of the lenses in the plurality of lens components LA: The distance on the optical axis from the lens surface on the scanning mechanism side in the lens component closest to the scanning mechanism 31 to the lens surface on the objective optical system side in the lens component closest to the objective optical system 25

[0015] According to the present embodiment, by making the lens surfaces at both ends of the scanning optical system SL symmetrical, it is possible to satisfactorily correct field curvature and spherical aberration, and it is also possible to obtain a bright image. The scanning optical system SL according to the present embodiment may be the scanning optical system SL(2) shown in FIG. 6, may be the scanning optical system SL(3) shown in FIG. 10, or may be the scanning optical system SL(4) shown in FIG. 14.

[0016] The conditional expression (1) defines an appropriate relationship between the sum of nd×tc / νd of the lenses in a plurality of lens components and the distance on the optical axis from the lens surface on the scanning mechanism side in the lens component closest to the scanning mechanism 31 to the lens surface on the objective optical system side in the lens component closest to the objective optical system 25. Note that the central thickness (tc) of the lens is the distance on the optical axis from the lens surface on the scanning mechanism side of the lens to the lens surface on the objective optical system side of the lens.

[0017] By the way, as an observation method of a microscope in which a non-linear optical effect can be obtained at a location where the photon density is high during fluorescence observation, an observation method of a two-photon excitation microscope (also referred to as a multi-photon excitation microscope) is known. As described above, the multi-photon excitation microscope is configured using a scanning confocal microscope. In a multi-photon excitation microscope, in order to cause multi-photon excitation with high excitation efficiency, it is necessary to instantaneously increase the photon density by using pulsed laser light as the excitation light. The optical pulse of the excitation light preferably has an extremely sharp waveform with a very narrow pulse width. However, when the optical pulse propagates through a medium having group velocity dispersion (for example, a lens or the like), the pulse width (time width) of the optical pulse spreads.

[0018] Group velocity dispersion (GVD: Group Velocity Dispersion) is a phenomenon in which the group velocity (the velocity at which a wave packet propagates) changes depending on the wavelength. When the wavelength of light is λ, the speed of light is c, and the refractive index of the medium is n(λ), the group velocity dispersion GVD is expressed by the following formula (A).

[0019]

Equation

[0020] The formula (A) for group velocity dispersion GVD can be obtained based on the formulas of the propagation constant k and the optical frequency ω. The second-order component k2 obtained from the propagation constant k, that is, the formula for the group velocity dispersion GVD and the optical frequency ω, is represented by the following formula (B) (for details of the propagation constant k, refer to "Nonlinear Optics Second Edition" by Robert W. Boyd (ISBN: 0-12-121682-9), P. 358-360).

[0021]

Number

[0022] The product of the group velocity dispersion GVD and the central thickness of the lens is called the group delay dispersion (GDD: Group Delay Dispersion). When the group delay dispersion GDD increases, the pulse width (time width) of the optical pulse broadens, and the excitation efficiency of multi-photon excitation decreases. Therefore, in conventional multi-photon excitation microscopes, it has been difficult to generate multi-photon excitation with high excitation efficiency to obtain a bright image.

[0023] In this embodiment, by satisfying the conditional expression (1), the total sum of the central thicknesses of the lenses becomes small, so the optical path length of the light passing through the lenses becomes short, and the group delay dispersion GDD can be reduced. Also, by satisfying the conditional expression (1), the sum of the reciprocals of the Abbe numbers, that is, the values indicating dispersion, becomes small, so the dispersion of the medium (lens) on the optical path becomes small, and the group delay dispersion GDD can be reduced. Thus, by satisfying the conditional expression (1), the group delay dispersion GDD can be reduced, so it becomes possible to generate multi-photon excitation with high excitation efficiency to obtain a bright image.

[0024] When the corresponding value of conditional expression (1) exceeds the upper limit value, the total center thickness of the lenses increases, so the optical path length of the light passing through the lenses becomes longer. As a result, the group delay dispersion GDD increases, making it difficult to generate multi-photon excitation with high excitation efficiency and obtain a bright image. By setting the upper limit value of conditional expression (1) to 0.02 and further to 0.018, the effects of this embodiment can be made more certain.

[0025] When the corresponding value of conditional expression (1) is below the lower limit value, the total center thickness of the lenses becomes too small, making it difficult to correct aberrations such as field curvature and spherical aberration. By setting the lower limit value of conditional expression (1) to 0.01, 0.013, and further to 0.015, the effects of this embodiment can be made more certain.

[0026] The scanning optical system SL according to this embodiment may satisfy the following conditional expressions (2) and (3). -3 < (ndA - 1) / rA × f < -0.6 ···(2) 0.5 < (ndE - 1) / rE × f < 3 ···(3) However, ndA: the refractive index with respect to the d-line of the lens closest to the scanning mechanism 31 among the lenses constituting the plurality of lens components rA: the radius of curvature of the lens surface on the scanning mechanism side in the lens closest to the scanning mechanism 31 ndE: the refractive index with respect to the d-line of the lens closest to the objective optical system 25 among the lenses constituting the plurality of lens components rE: the radius of curvature of the lens surface on the objective optical system side in the lens closest to the objective optical system 25 f: the focal length of the scanning optical system SL

[0027] Conditional expression (2) defines an appropriate relationship among the refractive index of the lens closest to the scanning mechanism 31 among the lenses constituting the plurality of lens components with respect to the d-line, the radius of curvature of the lens surface on the scanning mechanism side in the lens closest to the scanning mechanism 31, and the focal length of the scanning optical system SL. Conditional expression (3) defines an appropriate relationship among the refractive index of the lens closest to the objective optical system 25 among the lenses constituting the plurality of lens components with respect to the d-line, the radius of curvature of the lens surface on the objective optical system side in the lens closest to the objective optical system 25, and the focal length of the scanning optical system SL. The radius of curvature of the lens surface is defined as a positive value when the center of curvature is located on the objective optical system side (image plane side). By satisfying conditional expression (2) and conditional expression (3), it becomes possible to make the lens surfaces at both ends in the scanning optical system SL symmetric, and it is possible to favorably correct field curvature and astigmatism.

[0028] If the corresponding value of conditional expression (2) is out of the above range, it becomes difficult to make the lens surfaces at both ends in the scanning optical system SL symmetric, and it becomes difficult to correct field curvature and astigmatism. By setting the upper limit value of conditional expression (2) to -0.8, -1, and further -1.2, the effects of the present embodiment can be made more certain. By setting the lower limit value of conditional expression (2) to -2.5, -2, and further -1.5, the effects of the present embodiment can be made more certain.

[0029] If the corresponding value of conditional expression (3) is out of the above range, it becomes difficult to make the lens surfaces at both ends in the scanning optical system SL symmetric, and it becomes difficult to correct field curvature and astigmatism. By setting the upper limit value of conditional expression (3) to 2.5, 2, and further 1.8, the effects of the present embodiment can be made more certain. By setting the lower limit value of conditional expression (3) to 0.54, 0.8, 1, and further 1.2, the effects of the present embodiment can be made more certain.

[0030] In the scanning optical system SL according to the present embodiment, some of the plurality of lens components may consist of one positive lens and satisfy the following conditional expressions (4) and (5). νdP < 38 ···(4) 0.651 < θgFP + (0.001682 × νdP) ···(5) However, νdP: Abbe number of the positive lens θgFP: partial dispersion ratio of the positive lens. When the refractive index for the g-line of the positive lens is ngP, the refractive index for the F-line of the positive lens is nFP, and the refractive index for the C-line of the positive lens is nCP, it is defined by the following formula θgFP = (ngP - nFP) / (nFP - nCP)

[0031] Conditional expression (4) defines an appropriate range for the Abbe number of the positive lens. Conditional expression (5) defines an appropriate relationship between the partial dispersion ratio of the positive lens and the Abbe number of the positive lens. By satisfying conditional expressions (4) and (5), in addition to primary color correction, secondary spectrum can be well corrected in the correction of magnification chromatic aberration and axial chromatic aberration over a wide wavelength range.

[0032] When the corresponding value of conditional expression (4) exceeds the upper limit value, it becomes difficult to correct the secondary spectrum of magnification chromatic aberration and axial chromatic aberration. By setting the upper limit value of conditional expression (4) to 37, and further to 36, the effect of this embodiment can be made more certain.

[0033] When the corresponding value of conditional expression (5) is below the lower limit value, it becomes difficult to correct the secondary spectrum of magnification chromatic aberration and axial chromatic aberration. By setting the lower limit value of conditional expression (5) to 0.652, the effect of this embodiment can be made more certain. Also, by setting the upper limit value of conditional expression (5) to 0.85, 0.8, 0.75, and further to less than 0.7, the effect of this embodiment can be made more certain.

[0034] The scanning optical system SL according to this embodiment may satisfy the following conditional expression (6). 1 < fP / f < 5 ···(6) However, fP: focal length of the positive lens f: focal length of the scanning optical system SL

[0035] Conditional expression (6) defines an appropriate relationship between the focal length of the positive lens and the focal length of the scanning optical system SL. By satisfying conditional expression (6), since the focal length of the positive lens becomes longer, the radius of curvature of the lens surface in the positive lens becomes larger, and it becomes possible to reduce the center thickness of the positive lens. As a result, the optical path length of the light passing through the positive lens becomes shorter, and the group delay dispersion GDD can be reduced. Therefore, it becomes possible to generate multi-photon excitation with high excitation efficiency and obtain a bright image.

[0036] When the corresponding value of conditional expression (6) exceeds the upper limit value, since the focal length of the scanning optical system SL becomes shorter, the radius of curvature of the lens surface in the lenses other than the aforementioned positive lens tends to become smaller, and it becomes difficult to reduce the center thickness of the lens. As a result, the optical path length of the light passing through the lens becomes longer, and the group delay dispersion GDD becomes larger. Therefore, it becomes difficult to generate multi-photon excitation with high excitation efficiency and obtain a bright image. By setting the upper limit value of conditional expression (6) to 4.5, 4.0, and further 3.0, the effects of the present embodiment can be made more certain.

[0037] When the corresponding value of conditional expression (6) is below the lower limit value, since the focal length of the positive lens becomes shorter, the radius of curvature of the lens surface in the positive lens becomes smaller, and it becomes difficult to reduce the center thickness of the positive lens. As a result, the optical path length of the light passing through the positive lens becomes longer, and the group delay dispersion GDD becomes larger. Therefore, it becomes difficult to generate multi-photon excitation with high excitation efficiency and obtain a bright image. By setting the lower limit value of conditional expression (6) to 1.1, 1.2, and further 1.25, the effects of the present embodiment can be made more certain.

[0038] The scanning optical system SL according to the present embodiment may satisfy the following conditional expression (7). 0.7 < D0 / f < 1 ···(7) However, D0: The distance on the optical axis between the scanning mechanism 31 and the lens component closest to the scanning mechanism 31 f: The focal length of the scanning optical system SL

[0039] The conditional expression (7) defines an appropriate relationship between the distance on the optical axis between the scanning mechanism 31 and the lens component closest to the scanning mechanism 31, and the focal length of the scanning optical system SL. By satisfying the conditional expression (7), the distance on the optical axis between the scanning mechanism 31 and the lens component closest to the scanning mechanism 31 becomes wider, so that components for holding the scanning mechanism 31 and components for driving the scanning mechanism 31 can be easily incorporated.

[0040] When the corresponding value of the conditional expression (7) exceeds the upper limit value, the focal length of the scanning optical system SL becomes shorter. Therefore, the radius of curvature of the lens surface in each lens tends to become smaller, and it becomes difficult to reduce the center thickness of the lens. As a result, the optical path length of the light passing through the lens becomes longer and the group delay dispersion GDD becomes larger, making it difficult to generate multi-photon excitation with high excitation efficiency and obtain a bright image. By setting the upper limit value of the conditional expression (7) to 0.95, 0.9, 0.8, and further 0.75, the effects of the present embodiment can be made more reliable.

[0041] When the corresponding value of the conditional expression (7) is below the lower limit value, the distance on the optical axis between the scanning mechanism 31 and the lens component closest to the scanning mechanism 31 becomes narrower, so that it becomes difficult to incorporate components for holding the scanning mechanism 31 and components for driving the scanning mechanism 31. By setting the lower limit value of the conditional expression (7) to 0.72, the effects of the present embodiment can be made more reliable.

[0042] The scanning optical system SL according to the present embodiment may satisfy the following conditional expression (8). 0.5 < (Σtc) / LA < 0.9 ···(8) However, Σtc: The sum of the tc of the lenses in a plurality of lens components

[0043] The conditional expression (8) defines an appropriate relationship between the sum of the center thicknesses (tc) of the lenses in the plurality of lens components and the distance on the optical axis from the lens surface on the scanning mechanism side in the lens component closest to the scanning mechanism 31 to the lens surface on the objective optical system side in the lens component closest to the objective optical system 25. By satisfying the conditional expression (8), the sum of the center thicknesses of the lenses becomes smaller, so the optical path length of the light passing through the lenses becomes shorter. As a result, the group delay dispersion GDD can be reduced, so it becomes possible to generate multiphoton excitation with high excitation efficiency and obtain a bright image.

[0044] When the corresponding value of the conditional expression (8) exceeds the upper limit value, the sum of the center thicknesses of the lenses becomes larger, so the optical path length of the light passing through the lenses becomes longer. As a result, the group delay dispersion GDD becomes larger, so it becomes difficult to generate multiphoton excitation with high excitation efficiency and obtain a bright image. By setting the upper limit value of the conditional expression (8) to 0.85, 0.8, and further 0.75, the effects of the present embodiment can be made more reliable.

[0045] When the corresponding value of the conditional expression (8) is below the lower limit value, the sum of the center thicknesses of the lenses becomes too small, so it becomes difficult to correct aberrations such as field curvature and spherical aberration. By setting the lower limit value of the conditional expression (8) to 0.6 and further 0.65, the effects of the present embodiment can be made more reliable.

[0046] In the scanning optical system SL according to the present embodiment, the plurality of lens components may include a first lens component, a second lens component, a third lens component, and a fourth lens component arranged in order from the side of the scanning mechanism 31 (pupil conjugate plane P) along the optical axis, and may satisfy the following conditional expressions (9) to (11). 0 < D3 / D2 < 1 ···(9) 0.04 < D2 / TL < 0.11 ···(10) 0.02 < D3 / TL < 0.05 ···(11) However, D2: The air interval on the optical axis between the second lens component and the third lens component D3: The air interval on the optical axis between the third lens component and the fourth lens component The distance on the optical axis between the pupil conjugate plane P disposed on the scanning mechanism side of the scanning optical system SL and the image plane I disposed on the objective optical system side of the scanning optical system SL

[0047] Conditional expression (9) defines an appropriate relationship between the air space on the optical axis between the third lens component and the fourth lens component and the air space on the optical axis between the second lens component and the third lens component. Conditional expression (10) defines an appropriate relationship between the air space on the optical axis between the second lens component and the third lens component and the overall length of the scanning optical system SL, that is, the distance on the optical axis between the pupil conjugate plane P disposed on the scanning mechanism side of the scanning optical system SL and the image plane I (imaging plane 13) disposed on the objective optical system side of the scanning optical system SL. Conditional expression (12) defines an appropriate relationship between the air space on the optical axis between the third lens component and the fourth lens component and the distance on the optical axis between the pupil conjugate plane P disposed on the scanning mechanism side of the scanning optical system SL and the image plane I (imaging plane 13) disposed on the objective optical system side of the scanning optical system SL. By satisfying conditional expressions (9) to (11), the scanning optical system SL can be made closer to telecentric with respect to the imaging plane 13 (primary image plane), and thus it becomes possible to correct spherical aberration well.

[0048] If the corresponding value of conditional expression (9) falls outside the above range, the scanning optical system SL cannot be made closer to telecentric, and it becomes difficult to correct spherical aberration. By setting the upper limit value of conditional expression (9) to 0.9, 0.8, and further to 0.75, the effects of the present embodiment can be made more certain. By setting the lower limit value of conditional expression (9) to 0.1, 0.2, and further to 0.25, the effects of the present embodiment can be made more certain.

[0049] If the corresponding value of conditional expression (10) falls outside the above range, the scanning optical system SL cannot be made closer to telecentric, and it becomes difficult to correct spherical aberration. By setting the upper limit value of conditional expression (10) to 0.1 and further to 0.09, the effects of the present embodiment can be made more certain. By setting the lower limit value of conditional expression (10) to 0.044, the effects of the present embodiment can be made more certain.

[0050] If the corresponding value of conditional expression (11) is out of the above range, the scanning optical system SL cannot be made close to telecentric, and it becomes difficult to correct astigmatism. By setting the upper limit value of conditional expression (11) to 0.04, the effect of this embodiment can be made more certain. By setting the lower limit value of conditional expression (9) to 0.023, the effect of this embodiment can be made more certain.

[0051] The scanning optical system SL according to this embodiment may satisfy the following conditional expression (12). 0.000214<Σ(nd×tc / νd 2 ) / LA<0.000429 ···(12) However, Σ(nd×tc / νd 2 ): nd×tc / νd of lenses in multiple lens components 2 The sum of

[0052] Condition (12) is defined as nd×tc / νd of the lenses in a plurality of lens components. 2 and the appropriate relationship between the sum of the center thicknesses of the lenses and the distance on the optical axis from the lens surface on the scanning mechanism side of the lens component closest to the scanning mechanism 31 to the lens surface on the objective optical system side of the lens component closest to the objective optical system 25. By satisfying conditional expression (12), the sum of the center thicknesses of the lenses is reduced, so that the optical path length of the light passing through the lenses is shortened, and the group delay dispersion GDD can be reduced. Furthermore, by satisfying conditional expression (12), the reciprocal of the square of the Abbe number, i.e., the sum of the squares of the values ​​indicating the dispersion, is reduced, so that the dispersion of the medium (lens) on the optical path is reduced, and the group delay dispersion GDD can be reduced. In this way, by satisfying conditional expression (12), the group delay dispersion GDD can be reduced, so that it is possible to generate multiphoton excitation with high excitation efficiency and obtain a bright image.

[0053] When the corresponding value of conditional expression (12) exceeds the upper limit value, the total central thickness of the lenses increases, so the optical path length of the light passing through the lenses becomes longer. As a result, the group delay dispersion GDD increases, making it difficult to generate multi-photon excitation with high excitation efficiency and obtain a bright image. By setting the upper limit value of conditional expression (12) to 0.0004, 0.00035, and further 0.00033, the effects of the present embodiment can be made more reliable.

[0054] When the corresponding value of conditional expression (12) is below the lower limit value, the total central thickness of the lenses becomes too small, making it difficult to correct aberrations such as field curvature and astigmatism. By setting the lower limit value of conditional expression (12) to 0.00025 and further 0.00028, the effects of the present embodiment can be made more reliable.

Example

[0055] Hereinafter, an example of the scanning optical system SL provided in the scanning microscope according to the present embodiment will be described with reference to the drawings. FIGS. 2, 6, 10, and 14 are cross-sectional views showing the configurations and refractive power distributions of the scanning optical systems SL {SL(1) to SL(4)} according to the first to fourth embodiments. In these FIGS. 2, 6, 10, and 14, each lens component is represented by a combination of the symbol E and a number, and each lens is represented by a combination of the symbol L and a number. In this case, in order to prevent the types and numbers of symbols and numbers from becoming large and complicated, lens components etc. are represented by using combinations of symbols and numbers independently for each embodiment. Therefore, even if the same combination of symbol and number is used between embodiments, it does not mean the same configuration.

[0056] Tables 1 to 4 are shown below. Among them, Table 1 shows the specification data in the first embodiment, Table 2 shows the specification data in the second embodiment, Table 3 shows the specification data in the third embodiment, and Table 4 shows the specification data in the fourth embodiment. In each embodiment, d-line (wavelength λ = 587.6 nm), C-line (wavelength λ = 656.3 nm), F-line (wavelength λ = 486.1 nm), and g-line (wavelength λ = 435.8 nm) are selected as the objects for calculating aberration characteristics.

[0057] In the table of [Overall Specifications], f indicates the focal length of the scanning optical system. Φ indicates the pupil diameter. FNO indicates the F-number of the scanning optical system. Y indicates the maximum image height of the scanning optical system. TL indicates the overall length of the scanning optical system (the distance on the optical axis between the pupil conjugate plane arranged on the scanning mechanism side of the scanning optical system and the image plane arranged on the objective optical system side of the scanning optical system).

[0058] In the table of [Lens Specifications], the surface number indicates the order of the optical surfaces from the pupil conjugate plane (scanning mechanism) side along the direction of light ray propagation. R indicates the radius of curvature of each optical surface (a surface with the center of curvature located on the image plane side is defined as a positive value). D indicates the surface interval, which is the distance on the optical axis from each optical surface to the next optical surface (or the image plane). νd indicates the Abbe number of the material of the optical member based on the d-line. nd indicates the refractive index of the material of the optical member with respect to the d-line. θgF indicates the partial dispersion ratio of the material of the optical member. The "∞" for the radius of curvature indicates a plane or an aperture. The description of the refractive index of air nd = 1.00000 is omitted.

[0059] Let ng be the refractive index of the material of the optical member with respect to the g-line (wavelength λ = 435.8 nm), nF be the refractive index of the material of the optical member with respect to the F-line (wavelength λ = 486.1 nm), and nC be the refractive index of the material of the optical member with respect to the C-line (wavelength λ = 656.3 nm). At this time, the partial dispersion ratio θgF of the material of the optical member is defined by the following formula (C).

[0060] θgF = (ng - nF) / (nF - nC) …(C)

[0061] In the table of [Lens Component Data], the starting surface (the most object-side surface) and the focal length of each lens component are shown.

[0062] Hereinafter, in all specification values, the published focal length f, radius of curvature R, surface interval D, and other lengths, etc. generally use "mm" when not otherwise specified. However, since the optical system can obtain the same optical performance even when proportionally enlarged or reduced, it is not limited to this.

[0063] The explanations of the tables so far are common to all embodiments, and the overlapping explanations below are omitted.

[0064] (First Embodiment) The first embodiment will be described with reference to FIGS. 2 to 5 and Table 1. FIG. 2 is a cross-sectional view showing the configuration of the scanning optical system according to the first embodiment. The scanning optical system SL(1) according to the first embodiment includes a first lens component E1 having a negative refractive power, a second lens component E2 having a positive refractive power, a third lens component E3 having a positive refractive power, a fourth lens component E4 having a positive refractive power, and a fifth lens component E5 having a negative refractive power, which are arranged in order from the pupil conjugate plane P side along the optical axis. In the vicinity of the pupil conjugate plane P conjugate to the pupil plane of the objective optical system 25 (objective lens 24), the above-described scanning mechanism 31 (galvano mirror or the like) is arranged. The image plane I corresponds to the above-described imaging plane 13. This is the same in all the following embodiments.

[0065] The first lens component E1 is composed of a negative meniscus lens L11 with a concave surface facing the object side. The second lens component E2 is composed of a cemented lens having a positive refractive power, in which a negative lens L21 with a biconcave shape and a positive lens L22 with a biconvex shape are cemented in order from the object side. The third lens component E3 is composed of a positive meniscus lens L31 with a convex surface facing the object side. The fourth lens component E4 is composed of a cemented lens having a positive refractive power, in which a negative meniscus lens L41 with a convex surface facing the object side and a positive lens L42 with a biconvex shape are cemented in order from the object side. The fifth lens component E5 is composed of a cemented lens having a negative refractive power, in which a positive lens L51 with a biconvex shape and a negative lens L52 with a biconcave shape are cemented in order from the object side. The image plane I is arranged on the objective optical system side of the fifth lens component E5.

[0066] The values of the specifications of the scanning optical system according to the first embodiment are listed in Table 1 below. Note that the first surface is the pupil conjugate plane P.

[0067] (Table 1) [Overall Specifications] f = 60.007 Φ = 6.000 FNO = 10.001 Y = 12.5 TL = 150.755 [Lens Specifications] Surface number R D νd nd θgF 1 ∞ 45.000 2 -22.423 4.000 1.51680 64.13 3 -27.741 2.050 4 -148.175 3.000 1.61340 44.27 5 52.693 11.000 1.45600 91.37 6 -43.165 11.850 7 43.305 6.500 1.59270 35.31 0.59330 8 164.546 5.100 9 62.465 3.300 1.71999 50.27 10 25.694 12.000 1.49782 82.57 11 -74.529 1.000 12 38.062 8.100 1.49782 82.57 13 -52.973 2.100 1.71700 47.97 14 31.944 35.755 [Lens component data] Lens component Starting surface Focal length E1 2 -304.2894 E2 4 245.926 E3 7 97.2227 E4 9 105.951 E5 12 -87.952

[0068] FIG. 3 is a diagram showing various aberrations (spherical aberration, field curvature, and distortion) of the scanning optical system according to the first embodiment. FIG. 4 is a diagram showing the chromatic aberration of magnification (lateral chromatic aberration) of the scanning optical system according to the first embodiment. FIG. 5 is a diagram showing the coma aberration (meridional coma aberration and sagittal coma aberration) of the scanning optical system according to the first embodiment. In each aberration diagram of FIGS. 3 to 5, d represents various aberrations with respect to the d-line (wavelength λ = 587.6 nm), C represents the C-line (wavelength λ = 656.3 nm), F represents the F-line (wavelength λ = 486.1 nm), and g represents the g-line (wavelength λ = 435.8 nm). In the spherical aberration diagram, the vertical axis represents the value normalized with the maximum value of the entrance pupil radius being 1, and the horizontal axis represents the value of the aberration [mm] for each ray. In the aberration diagram showing field curvature, the solid line represents the meridional image plane for each wavelength, and the dashed line represents the sagittal image plane for each wavelength. Also, in the aberration diagram showing field curvature, the vertical axis represents the image height [mm], and the horizontal axis represents the value of the aberration [mm]. In the distortion aberration diagram (distortion), the vertical axis represents the image height [mm], and the horizontal axis represents the ratio of the aberration as a percentage (% value). In the aberration diagram showing chromatic aberration of magnification, the vertical axis represents the image height [mm], and the horizontal axis represents the value of the aberration [mm]. Each coma aberration diagram shows the value of the aberration when the relative field height RFH (Relative Field Height) is 0.00 and 1.00. Note that in the aberration diagrams of each of the following embodiments, the same reference numerals as in this embodiment are used, and duplicate explanations are omitted.

[0069] From each aberration diagram, it can be seen that the scanning optical system according to the first embodiment has various aberrations such as field curvature well corrected and has excellent optical performance.

[0070] (Second Embodiment) The second embodiment will be described with reference to FIGS. 6 to 9 and Table 2. FIG. 6 is a cross-sectional view showing the configuration of the scanning optical system according to the second embodiment. The scanning optical system SL(2) according to the second embodiment includes a first lens component E1 having a negative refractive power, a second lens component E2 having a positive refractive power, a third lens component E3 having a positive refractive power, a fourth lens component E4 having a positive refractive power, and a fifth lens component E5 having a negative refractive power, arranged in order from the pupil conjugate plane P side along the optical axis.

[0071] The first lens component E1 is composed of a negative meniscus lens L11 with a concave surface facing the object side. The second lens component E2 is composed of a cemented lens having a positive refractive power, in which a positive meniscus lens L21 with a concave surface facing the object side and a negative meniscus lens L22 with a concave surface facing the object side are cemented in order from the object side. The third lens component E3 is composed of a biconvex positive lens L31. The fourth lens component E4 is composed of a cemented lens having a positive refractive power, in which a negative meniscus lens L41 with a convex surface facing the object side and a biconvex positive lens L42 are cemented in order from the object side. The fifth lens component E5 is composed of a cemented lens having a negative refractive power, in which a biconvex positive lens L51 and a biconcave negative lens L52 are cemented in order from the object side. An image plane I is disposed on the objective optical system side of the fifth lens component E5.

[0072] The following Table 2 lists the specifications of the scanning optical system according to the second embodiment. Note that the first surface is the pupil conjugate plane P.

[0073] (Table 2) [Overall specifications] f = 60.005 Φ = 6.000 FNO = 10.001 Y = 12.5 TL = 151.008 [Lens specifications] Surface number R D νd nd θgF 1 ∞ 44.918 2 -21.949 4.000 1.49782 82.57 3 -24.402 1.000 4 -92.175 10.000 1.45600 91.37 5 -20.414 2.000 1.61340 44.27 6 -49.625 12.400 7 112.878 6.000 1.59270 35.31 0.59330 8 -100.513 3.600 9 132.598 2.000 1.71999 50.27 10 39.170 12.000 1.49782 82.57 11 -56.922 3.700 12 31.222 9.346 1.49782 82.57 13 -76.382 4.252 1.71700 47.97 14 27.709 35.792 [Lens component data] Lens component Starting surface Focal length E1 2 -958.2426 E2 4 16917.854 E3 7 90.654 E4 9 117.667 E5 12 -110.067

[0074] FIG. 7 is a diagram showing various aberrations (spherical aberration, field curvature, and distortion) of the scanning optical system according to the second embodiment. FIG. 8 is a diagram showing the chromatic aberration of magnification (lateral chromatic aberration) of the scanning optical system according to the second embodiment. FIG. 9 is a diagram showing the coma aberration (meridional coma aberration and sagittal coma aberration) of the scanning optical system according to the second embodiment. From each aberration diagram, it can be seen that the scanning optical system according to the second embodiment has good correction of various aberrations including field curvature and has excellent optical performance.

[0075] (Third Embodiment) The third embodiment will be described with reference to FIGS. 10 to 13 and Table 3. FIG. 10 is a cross-sectional view showing the configuration of the scanning optical system according to the third embodiment. The scanning optical system SL(3) according to the third embodiment includes a first lens component E1 having a positive refractive power, a second lens component E2 having a negative refractive power, a third lens component E3 having a positive refractive power, a fourth lens component E4 having a positive refractive power, and a fifth lens component E5 having a negative refractive power, which are arranged in order from the pupil conjugate plane P side along the optical axis.

[0076] The first lens component E1 is composed of a positive meniscus lens L11 with a concave surface facing the object side. The second lens component E2 is composed of a cemented lens having a negative refractive power, in which a positive meniscus lens L21 with a concave surface facing the object side and a negative meniscus lens L22 with a concave surface facing the object side are cemented in order from the object side. The third lens component E3 is composed of a biconvex positive lens L31. The fourth lens component E4 is composed of a cemented lens having a positive refractive power, in which a biconvex positive lens L41 and a negative meniscus lens L42 with a concave surface facing the object side are cemented in order from the object side. The fifth lens component E5 is composed of a cemented lens having a negative refractive power, in which a biconvex positive lens L51 and a biconcave negative lens L52 are cemented in order from the object side. An image plane I is disposed on the objective optical system side of the fifth lens component E5.

[0077] The following Table 3 lists the specifications of the scanning optical system according to the third embodiment. Note that the first surface is the pupil conjugate plane P.

[0078] (Table 3) [Overall specifications] f = 60.107 Φ = 6.000 FNO = 10.018 Y = 12.5 TL = 151.074 [Lens specifications] Surface number R D νd nd θgF 1 ∞ 44.611 2 -23.778 6.500 1.49782 82.57 3 -25.845 7.682 4 -4387.269 8.900 1.45600 91.37 5 -22.184 2.000 1.61340 44.27 6 -161.406 6.738 7 113.647 7.000 1.59270 35.31 0.59330 8 -76.829 4.758 9 92.860 10.000 1.45600 91.37 10 -41.084 2.000 1.71999 50.27 11 -55.984 2.711 12 32.094 10.100 1.49782 82.57 13 -60.391 2.300 1.71700 47.97 14 25.452 35.774 [Lens component data] Lens component Starting surface Focal length E1 2 13343.5318 E2 4 -297.000 E3 7 78.4127 E4 9 89.701 E5 12 -79.999

[0079] FIG. 11 is a diagram showing various aberrations (spherical aberration, field curvature, and distortion) of the scanning optical system according to the third embodiment. FIG. 12 is a diagram showing the chromatic aberration of magnification (lateral chromatic aberration) of the scanning optical system according to the third embodiment. FIG. 13 is a diagram showing the coma aberration (meridional coma aberration and sagittal coma aberration) of the scanning optical system according to the third embodiment. From each aberration diagram, it can be seen that the scanning optical system according to the third embodiment has various aberrations including field curvature well corrected and has excellent optical performance.

[0080] (Fourth Embodiment) The fourth embodiment will be described with reference to FIGS. 14 to 17 and Table 4. FIG. 14 is a cross-sectional view showing the configuration of the scanning optical system according to the fourth embodiment. The scanning optical system SL(4) according to the fourth embodiment includes a first lens component E1 having a negative refractive power, a second lens component E2 having a positive refractive power, a third lens component E3 having a positive refractive power, a fourth lens component E4 having a positive refractive power, and a fifth lens component E5 having a negative refractive power, which are arranged in order from the pupil conjugate plane P side along the optical axis.

[0081] The first lens component E1 is composed of a negative meniscus lens L11 with a concave surface facing the object side. The second lens component E2 is composed of a cemented lens having a positive refractive power, in which a biconcave negative lens L21 and a biconvex positive lens L22 are cemented in order from the object side. The third lens component E3 is composed of a positive meniscus lens L31 with a convex surface facing the object side. The fourth lens component E4 is composed of a cemented lens having a positive refractive power, in which a biconvex positive lens L41 and a negative meniscus lens L42 with a concave surface facing the object side are cemented in order from the object side. The fifth lens component E5 is composed of a cemented lens having a negative refractive power, in which a biconvex positive lens L51 and a biconcave negative lens L52 are cemented in order from the object side. An image plane I is disposed on the side of the objective optical system of the fifth lens component E5.

[0082] The following Table 4 lists the values of the specifications of the scanning optical system according to the fourth embodiment. Note that the first surface is the pupil conjugate surface P.

[0083] (Table 4) [Overall specifications] f = 60.020 Φ = 6.000 FNO = 10.003 Y = 12.5 TL = 150.899 [Lens specifications] Surface number R D νd nd θgF 1 ∞ 45.000 2 -25.623 4.000 1.51680 64.13 3 -40.988 1.000 4 -203.374 2.400 1.71999 50.27 5 66.170 8.700 1.43425 94.77 6 -33.529 9.197 7 35.450 5.000 1.59270 35.31 0.59330 8 53.667 4.722 9 75.882 13.000 1.45600 91.37 10 -43.186 3.000 1.68376 37.64 11 -62.720 4.981 12 48.240 12.000 1.49782 82.57 13 -27.884 2.000 1.73400 51.51 14 78.861 35.899 [Lens component data] Lens component Starting surface Focal length E1 2 -145.127 E2 4 173.768 E3 7 159.8651 E4 9 88.375 E5 12 -167.764

[0084] FIG. 15 is a diagram showing various aberrations (spherical aberration, field curvature, and distortion) of the scanning optical system according to the fourth embodiment. FIG. 16 is a diagram showing the chromatic aberration of magnification (lateral chromatic aberration) of the scanning optical system according to the fourth embodiment. FIG. 17 is a diagram showing the coma aberration (meridional coma aberration and sagittal coma aberration) of the scanning optical system according to the fourth embodiment. From each aberration diagram, it can be seen that the scanning optical system according to the fourth embodiment has excellent optical performance with various aberrations including field curvature well corrected.

[0085] Next, a table of [conditional expression corresponding values] is shown below. This table collectively shows the values corresponding to each conditional expression (1) to (12) for all embodiments (the first to the fourth embodiments). Conditional expression (1) 0.007 < Σ(nd × tc / νd) / LA < 0.021 Conditional expression (2) -3 < (ndA - 1) / rA × f < -0.6 Conditional expression (3) 0.5 < (ndE - 1) / rE × f < 3 Conditional expression (4) νdP < 38 Conditional expression (5) 0.651 < θgFP + (0.001682 × νdP) Conditional expression (6) 1 < fP / f < 5 Conditional expression (7) 0.7 < D0 / f < 1 Conditional expression (8) 0.5 < (Σtc) / LA < 0.9 Conditional expression (9) 0 < D3 / D2 < 1 Conditional expression (10): 0.04 < D2 / TL < 0.11 Conditional expression (11): 0.02 < D3 / TL < 0.05 Conditional expression (12): 0.000214 < Σ(nd×tc / νd 2 ) / LA < 0.000429

[0086] [Corresponding value of conditional expression] Conditional expression 1st embodiment 2nd embodiment 3rd embodiment 4th embodiment (1) 0.0175 0.0168 0.0162 0.0166 (2) -1.383 -1.361 -1.258 -1.211 (3) 1.347 1.553 1.693 0.559 (4) 35.310 35.310 35.310 35.310 (5) 0.6527 0.6527 0.6527 0.6527 (6) 1.620 1.511 1.305 2.664 (7) 0.750 0.749 0.742 0.750 (8) 0.714 0.706 0.690 0.716 (9) 0.430 0.290 0.706 0.513 (10) 0.079 0.082 0.045 0.061 (11) 0.034 0.024 0.031 0.031 (12) 0.0003199 0.0003010 0.0002915 0.0002952

[0087] According to each of the above embodiments, it is possible to realize a scanning optical system and a scanning microscope that can favorably correct field curvature, spherical aberration, and chromatic aberration of magnification, and obtain a bright image.

[0088] Here, each of the above embodiments shows a specific example of the present embodiment, and the present embodiment is not limited thereto.

[0089] In each of the above embodiments, the first lens component E1 and the third lens component E3 are each composed of one lens, but the present invention is not limited thereto, and they may be composed of one cemented lens formed of a plurality of lenses cemented to each other. The second lens component E2, the fourth lens component E4, and the fifth lens component E5 are each composed of one cemented lens formed of a plurality of lenses cemented to each other, but the present invention is not limited thereto, and they may be composed of one lens.

Explanation of Signs

[0090] E1 First lens component E2 Second lens component E3 Third lens component E4 Fourth lens component E5 Fifth lens component I Image plane P Pupil conjugate plane

Claims

1. A scanning mechanism that scans a sample with light from a light source, An objective optical system that condenses the light from the scanning mechanism onto the sample, A scanning optical system provided between the scanning mechanism and the objective optical system, which guides the light from the scanning mechanism to the objective optical system, The scanning optical system is composed of a plurality of lens components arranged along the optical axis and has a positive refractive power as a whole, The lens component is composed of one cemented lens formed by a plurality of lenses cemented to each other or one lens, The lens surface on the scanning mechanism side in the lens component closest to the scanning mechanism among the plurality of lens components is a concave surface, The lens surface on the objective optical system side in the lens component closest to the objective optical system among the plurality of lens components is a concave surface, Satisfies the following conditional expression, 0.007 < Σ(nd × tc / νd) / LA < 0.021 However, Σ(nd × tc / νd): When the refractive index for the d-line of the lens constituting the plurality of lens components is nd, the center thickness of the lens is tc, and the Abbe number of the lens is νd, the sum of nd × tc / νd of the lens in the plurality of lens components LA: The distance on the optical axis from the lens surface on the scanning mechanism side in the lens component closest to the scanning mechanism to the lens surface on the objective optical system side in the lens component closest to the objective optical system Further, some of the plurality of lens components are composed of one positive lens, and a scanning microscope that satisfies the following conditional expression. νdP < 38 0.651 < θgFP + (0.001682 × νdP) However, νdP: The Abbe number of the positive lens θgFP: The partial dispersion ratio of the positive lens, and when the refractive index for the g-line of the positive lens is ngP, the refractive index for the F-line of the positive lens is nFP, and the refractive index for the C-line of the positive lens is nCP, it is defined by the following formula θgFP = (ngP - nFP) / (nFP - nCP)

2. The scanning microscope according to claim 1, which satisfies the following conditional expression. -3 < (ndA - 1) / rA × f < -0.6 0.5 < (ndE - 1) / rE × f < 3 Here, ndA: The refractive index with respect to the d-line of the lens closest to the scanning mechanism among the lenses constituting the plurality of lens components rA: The radius of curvature of the lens surface on the scanning mechanism side in the lens closest to the scanning mechanism ndE: The refractive index with respect to the d-line of the lens closest to the objective optical system among the lenses constituting the plurality of lens components rE: The radius of curvature of the lens surface on the objective optical system side in the lens closest to the objective optical system f: The focal length of the scanning optical system

3. The scanning microscope according to claim 1, which satisfies the following conditional expression. 1 < fP / f < 5 Here, fP: The focal length of the positive lens f: The focal length of the scanning optical system

4. The scanning microscope according to claim 1, which satisfies the following conditional expression. 0.7 < D0 / f < 1 Here, D0: The distance on the optical axis between the scanning mechanism and the lens component closest to the scanning mechanism f: The focal length of the scanning optical system

5. The scanning microscope according to claim 1, which satisfies the following conditional expression. 0.5 < (Σtc) / LA < 0.9 Here, Σtc: The total sum of tc of the lenses in the plurality of lens components

6. The plurality of lens components include a first lens component, a second lens component, a third lens component, and a fourth lens component, arranged in order from the scanning mechanism side along the optical axis, The scanning microscope according to claim 1, which satisfies the following conditional expression. 0 < D3 / D2 < 1 0.04 < D2 / TL < 0.11 0.02 < D3 / TL < 0.05 However, D2: the air interval on the optical axis between the second lens component and the third lens component D3: the air interval on the optical axis between the third lens component and the fourth lens component TL: the distance on the optical axis between the pupil conjugate plane arranged on the scanning mechanism side of the scanning optical system and the image plane arranged on the objective optical system side of the scanning optical system

7. The scanning microscope according to claim 1, which satisfies the following conditional expression. 0.000214 < Σ(nd × tc / νd2) / LA < 0.000429 However, Σ(nd × tc / νd2): the sum of nd × tc / νd2 of the lenses in the plurality of lens components

Images