Scanning microscope

Abstract

To provide a scanning microscope capable of obtaining bright images.SOLUTION: A scanning optical system SL of a scanning microscope consists of a plurality of lens components and has a positive refractive power as a whole. Each lens component is one cemented lens consisting of a plurality of lenses cemented together, or one lens. The following condition is satisfied: 0.007<Σ(nd×tc / νd) / LA<0.021, where Σ(nd×tc / νd): the sum of nd×tc / νd of the lenses in the plurality of lens components, where nd is a refractive index of a lens that comprises the plurality of lens components for a d-line, tc is a center thickness of the lens, and νd is an Abbe number of the lens. LA: a distance on an optical axis from a lens surface of a lens component closest to a scanning mechanism on the scanning mechanism side to a lens surface of a lens component closest to an objective optical system on the objective optical system side.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Conventionally, scanning microscopes equipped with a scanning optical system that guides light from a scanning mechanism to an objective optical system have been known (see, for example, Patent Document 1). With such scanning microscopes, it has been difficult to obtain bright images. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-102013 Summary of the Invention

[0004] A scanning microscope according to the present invention comprises a scanning mechanism that scans a sample with light from a light source, an objective optical system that focuses the light from the scanning mechanism on the sample, and a scanning optical system that is provided between the scanning mechanism and the objective optical system and guides the light from the scanning mechanism to the objective optical system, wherein the scanning optical system is made up of a plurality of lens components arranged along an optical axis and has a positive refractive power as a whole, the lens component is a cemented lens made up of a plurality of lenses cemented together, or is made up of a single lens, wherein the lens surface of the lens component closest to the scanning mechanism that faces the scanning mechanism is concave, and the lens surface of the lens component closest to the objective optical system that faces the objective optical system is concave, and the following conditional expression is satisfied: 0.007<Σ(nd×tc / νd) / LA<0.021 where Σ(nd×tc / νd): the sum of nd×tc / νd of the lenses in the plurality of lens components, where nd is the refractive index of the lenses with respect to the d line, tc is the center thickness of the lenses, and νd is the Abbe number of the lenses. LA: the distance on the optical axis from the lens surface of the lens component closest to the scanning mechanism on the side of the scanning mechanism to the lens surface of the lens component closest to the objective optical system on the side of the objective optical system [Brief explanation of the drawings]

[0005] [Figure 1] FIG. 1 is an explanatory diagram showing an example of a scanning microscope equipped with a scanning optical system. [Figure 2] FIG. 1 is a cross-sectional view showing the configuration of a scanning optical system according to a first embodiment. [Figure 3] 3A to 3C are diagrams showing various aberrations of the scanning optical system according to the first example. [Figure 4] FIG. 3 is a chromatic aberration diagram of the scanning optical system according to the first example. [Figure 5] FIG. 3 is a diagram illustrating coma aberration of the scanning optical system according to the first example. [Figure 6] FIG. 10 is a cross-sectional view showing the configuration of a scanning optical system according to a second embodiment. [Figure 7] 10A to 10C are diagrams showing various aberrations of the scanning optical system according to the second example. [Figure 8] FIG. 10 is a chromatic aberration diagram of the scanning optical system according to the second example. [Figure 9] FIG. 10 is a diagram illustrating coma aberration of the scanning optical system according to the second example. [Figure 10] FIG. 10 is a cross-sectional view showing the configuration of a scanning optical system according to a third example. [Figure 11] 10A to 10C are diagrams showing various aberrations of the scanning optical system according to the third example. [Figure 12] FIG. 10 is a chromatic aberration diagram of the scanning optical system according to the third example. [Figure 13] FIG. 10 is a diagram illustrating coma aberration of the scanning optical system according to the third example. [Figure 14] FIG. 10 is a cross-sectional view showing the configuration of a scanning optical system according to a fourth example. [Figure 15] 10A to 10C are diagrams showing various aberrations of the scanning optical system according to the fourth example. [Figure 16] FIG. 10 is a chromatic aberration diagram of the scanning optical system according to the fourth example. [Figure 17] 10A and 10B are diagrams illustrating coma aberration in the scanning optical system according to the fourth example. DETAILED DESCRIPTION OF THE INVENTION

[0006] A scanning microscope equipped with a scanning optical system according to this embodiment will be described below. First, a scanning confocal microscope 1 will be described as an example of a scanning microscope according to this embodiment, using Fig. 1. The scanning confocal microscope 1 is configured with an excitation light introducing section 2 that guides illumination laser light from a light source unit 6 onto a sample SA, a scanning device 3 that deflects the laser light focused on the sample SA to scan it over the sample SA, a photodetector 5 that detects a light intensity signal from the sample SA corresponding to multiphoton excitation, and a focusing optical system 4 that guides light from the sample SA to the photodetector 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) and a beam diameter adjustment mechanism (not shown), etc. The light source unit 6 oscillates pulsed laser light as illumination laser light.

[0008] The excitation light introducing section 2 is configured with a collimator lens 21, a dichroic mirror 22, and an objective optical system 25 consisting of a second objective lens 23 and an objective lens 24. The collimator lens 21 and the dichroic mirror 22 are arranged inside the microscope housing section 12 provided on top of the lens barrel section 11 of the microscope main body 10. The light source unit 6 and the microscope housing section 12 are connected by an optical fiber 69 using connectors C3 and C4. The collimator lens 21 converts the laser light (light beam) emitted 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 focuses the laser light reflected by the dichroic mirror 22 onto the sample SA using the second objective lens 23 and the objective lens 24. The second objective lens 23 is arranged inside the lens barrel section 11 of the microscope main body 10. The objective lens 24 is attached to the lower part of the lens barrel 11 .

[0009] The scanning device 3 is configured to include a scanning mechanism (scanner) 31 and a scanning optical system 32. The scanning device 3 is disposed inside the microscope housing 12 between the dichroic mirror 22 and the second objective lens 23. The scanning mechanism (scanner) 31 is configured to include, 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 focused 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. The scanning optical system 32 is an optical system in which the focal position of the scanning optical system 32 is located on an image plane 13 (also referred to as a primary image plane) conjugate with the sample SA (the scanning plane of the sample SA).

[0010] The focusing optical system 4 is configured to include the objective lens 24 and the second objective lens 23 that constitute the objective optical system 25, a total reflection mirror 41, and a focusing lens 42. The total reflection mirror 41 and the focusing 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 focusing lens 42 focuses the fluorescence reflected by the total reflection mirror 41.

[0011] The light detection device 5 is configured to include 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. Light (fluorescence) collected by the 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. The processing unit 57 performs image processing (of the sample SA) based on the detection signal detected by the detection unit 55, and the observed image of the sample SA obtained by the image processing of the processing unit 57 is displayed on a monitor (not shown).

[0012] The laser light from the scanning device 3 is first focused on the image plane 13 (primary image plane) and then focused again on the sample SA 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 image plane 13, and the plane of incidence of the light on the optical fiber 53 are conjugate with each other. Therefore, by focusing the light on the sample SA by the second objective lens 23 and the objective lens 24, it is possible to ensure that all of the fluorescence generated by multiphoton excitation that passes through the objective lens 24 reaches the detection unit 55. Furthermore, in the case of a multiphoton excitation confocal microscope, multiphoton 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, as with a conventional confocal microscope, without using a light shielding plate 52 with a pinhole (see the two-dot chain line in Figure 1).

[0013] The scanning optical system SL described below can be used as the scanning optical system 32. Here, the scanning optical system SL used in the scanning microscope (scanning confocal microscope 1) according to this embodiment will be described. The scanning optical system SL according to this embodiment is composed of a plurality of lens components arranged along the optical axis, for example, as in 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 cemented lens composed of a plurality of lenses cemented together, or a single lens. Of the plurality of lens components, the lens surface facing the scanning mechanism of the lens component closest to the scanning mechanism 31 (pupil conjugate plane P conjugate to the pupil plane of the objective optical system 25) is concave. Of the plurality of lens components, the lens surface facing the objective optical system of the lens component closest to the objective optical system 25 (image plane I) is concave.

[0014] With the above configuration, the scanning optical system SL according to this embodiment satisfies the following conditional expression (1). 0.007<Σ(nd×tc / νd) / LA<0.021 ···(1) where Σ(nd×tc / νd): the sum of nd×tc / νd of the lenses in the multiple lens components, where nd is the refractive index for the d-line of the lenses constituting the multiple lens components, tc is the center thickness of the lens, and νd is the Abbe number of the lens. LA: 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

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

[0016] Conditional formula (1) defines an appropriate relationship between the sum of nd×tc / νd of lenses in a plurality of lens components 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. The center thickness (tc) of a 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] Incidentally, two-photon excitation microscopy (also called multi-photon excitation microscopy) is a known microscopy observation method that can obtain nonlinear optical effects at locations with high photon density during fluorescence observation. As mentioned above, a multi-photon excitation microscope is configured using a scanning confocal microscope. In a multi-photon excitation microscope, to generate multi-photon excitation with high excitation efficiency, it is necessary to instantaneously increase the photon density by using pulsed laser light as excitation light. It is preferable that the optical pulse of the excitation light has a sharp waveform with an extremely narrow pulse width. However, when the optical pulse propagates through a medium with group velocity dispersion (e.g., a lens), the pulse width (time width) of the optical pulse widens.

[0018] Group velocity dispersion (GVD) is a phenomenon in which the group velocity (the speed at which a group of waves 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), group velocity dispersion GVD is expressed by the following formula (A).

[0019]

number

[0020] Formula (A) for group velocity dispersion GVD can be found based on the equation for propagation constant k and light frequency ω. The second-order component k2 found from the propagation constant k, that is, the equation for group velocity dispersion GVD and light frequency ω, is expressed as the following formula (B) (for details on the propagation constant k, see Robert W. Boyd, "Nonlinear Optics Second Edition" (ISBN: 0-12-121682-9), pp. 358-360).

[0021]

number

[0022] Group velocity dispersion (GVD) multiplied by the central thickness of the lens is called group delay dispersion (GDD). As group delay dispersion (GDD) increases, the pulse width (time width) of the optical pulse widens, reducing the excitation efficiency of multiphoton excitation. For this reason, it has been difficult with conventional multiphoton excitation microscopes to generate multiphoton excitation with high excitation efficiency and obtain bright images.

[0023] In this embodiment, satisfying conditional expression (1) reduces the total center thickness of the lens, thereby shortening the optical path length of light passing through the lens and reducing group delay dispersion (GDD). Furthermore, satisfying conditional expression (1) reduces the reciprocal of the Abbe number, i.e., the total sum of values indicating dispersion, thereby reducing the dispersion of the medium (lens) along the optical path and reducing group delay dispersion (GDD). Thus, satisfying conditional expression (1) reduces group delay dispersion (GDD), enabling multiphoton excitation with high excitation efficiency and the acquisition of bright images.

[0024] If the value corresponding to conditional expression (1) exceeds the upper limit, the total center thickness of the lens increases, and the optical path length of the light passing through the lens becomes longer. This increases the group delay dispersion (GDD), making it difficult to generate multiphoton excitation with high excitation efficiency and obtain a bright image. By setting the upper limit of conditional expression (1) to 0.02 or even 0.018, the effect of this embodiment can be further ensured.

[0025] If the corresponding value of conditional expression (1) falls below the lower limit, the total center thickness of the lens becomes too small, making it difficult to correct aberrations such as field curvature and astigmatism. By setting the lower limit of conditional expression (1) to 0.01, 0.013, or even 0.015, the effect of this embodiment can be further ensured.

[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) where ndA is the refractive index of the lens closest to the scanning mechanism 31 among the lenses constituting the plurality of lens components, at the d-line rA: Radius of curvature of the lens surface closest to the scanning mechanism 31 on the scanning mechanism side ndE: refractive index of the lens closest to the objective optical system 25 at the d line among the lenses constituting the plurality of lens components rE: radius of curvature of the lens surface closest to the objective optical system 25 on the objective optical system side f: focal length of the scanning optical system SL

[0027] Conditional formula (2) defines an appropriate relationship between the refractive index for the d-line of the lens closest to the scanning mechanism 31 among the lenses constituting the multiple lens components, the radius of curvature of the lens surface closest to the scanning mechanism 31 facing the scanning mechanism, and the focal length of the scanning optical system SL. Conditional formula (3) defines an appropriate relationship between the refractive index for the d-line of the lens closest to the objective optical system 25 among the lenses constituting the multiple lens components, the radius of curvature of the lens surface closest to the objective optical system 25 facing the objective optical system, and the focal length of the scanning optical system SL. The radius of curvature of the lens surface is set to a positive value when the center of curvature is located on the objective optical system side (image plane side). Satisfying conditional formulas (2) and (3) makes it possible to make the lens surfaces at both ends of the scanning optical system SL symmetrical, thereby enabling good correction of field curvature and astigmatism.

[0028] If the corresponding value of conditional expression (2) falls outside the above range, it becomes difficult to make the lens surfaces at both ends of the scanning optical system SL symmetrical, making it difficult to correct field curvature and astigmatism. By setting the upper limit of conditional expression (2) to -0.8, -1, or even -1.2, the effect of this embodiment can be more reliably achieved. By setting the lower limit of conditional expression (2) to -2.5, -2, or even -1.5, the effect of this embodiment can be more reliably achieved.

[0029] If the corresponding value of conditional expression (3) falls outside the above range, it becomes difficult to make the lens surfaces at both ends of the scanning optical system SL symmetrical, making it difficult to correct field curvature and astigmatism. By setting the upper limit of conditional expression (3) to 2.5, 2, or even 1.8, the effect of this embodiment can be more reliably achieved. By setting the lower limit of conditional expression (3) to 0.54, 0.8, 1, or even 1.2, the effect of this embodiment can be more reliably achieved.

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

[0031] Conditional formula (4) defines an appropriate range for the Abbe number of the positive lens. Conditional formula (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 formulas (4) and (5), it is possible to achieve excellent correction of secondary spectrum in addition to primary achromatism in correction of lateral chromatic aberration and axial chromatic aberration over a wide wavelength range.

[0032] If the corresponding value of conditional expression (4) exceeds the upper limit, it becomes difficult to correct the secondary spectrum of lateral chromatic aberration and axial chromatic aberration. By setting the upper limit of conditional expression (4) to 37, or even 36, the effect of this embodiment can be further ensured.

[0033] If the corresponding value of conditional expression (5) falls below the lower limit, it becomes difficult to correct the secondary spectrum of lateral chromatic aberration and axial chromatic aberration. By setting the lower limit of conditional expression (5) to 0.652, the effect of this embodiment can be more reliably achieved. Furthermore, by setting the upper limit of conditional expression (5) to 0.85, 0.8, 0.75, or even less than 0.7, the effect of this embodiment can be more reliably achieved.

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

[0035] Conditional expression (6) defines the 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), the focal length of the positive lens becomes longer, which increases the radius of curvature of the lens surface of the positive lens and makes it possible to reduce the central thickness of the positive lens. This shortens the optical path length of light passing through the positive lens and reduces the group delay dispersion (GDD), making it possible to generate multiphoton excitation with high excitation efficiency and obtain a bright image.

[0036] If the value corresponding to conditional expression (6) exceeds the upper limit, the focal length of the scanning optical system SL becomes shorter, which tends to reduce the radius of curvature of the lens surfaces of lenses other than the aforementioned positive lens, making it difficult to reduce the center thickness of the lens. This increases the optical path length of light passing through the lens and increases the group delay dispersion (GDD), making it difficult to generate multiphoton excitation with high excitation efficiency and obtain a bright image. Setting the upper limit of conditional expression (6) to 4.5, 4.0, or even 3.0 further enhances the effects of this embodiment.

[0037] If the value corresponding to conditional expression (6) is below the lower limit, the focal length of the positive lens becomes shorter, which reduces the radius of curvature of the lens surface of the positive lens, making it difficult to reduce the center thickness of the positive lens. This increases the optical path length of light passing through the positive lens and increases the group delay dispersion (GDD), making it difficult to generate multiphoton excitation with high excitation efficiency and obtain a bright image. Setting the lower limit of conditional expression (6) to 1.1, 1.2, or even 1.25 further enhances the effects of this embodiment.

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

[0039] Conditional expression (7) defines an appropriate relationship between the focal length of the scanning optical system SL and the distance on the optical axis between the scanning mechanism 31 and the lens component closest to the scanning mechanism 31. By satisfying 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 wide, making it possible to easily incorporate components that hold the scanning mechanism 31 and components that drive the scanning mechanism 31.

[0040] If the value corresponding to conditional expression (7) exceeds the upper limit, the focal length of the scanning optical system SL becomes shorter, which tends to reduce the radius of curvature of the lens surface of each lens, making it difficult to reduce the center thickness of the lens. This increases the optical path length of the light passing through the lens and increases the group delay dispersion (GDD), making it difficult to generate multiphoton excitation with high excitation efficiency and obtain a bright image. By setting the upper limit of conditional expression (7) to 0.95, 0.9, 0.8, or even 0.75, the effects of this embodiment can be further ensured.

[0041] If the corresponding value of conditional expression (7) falls below the lower limit, the distance on the optical axis between scanning mechanism 31 and the lens component closest to scanning mechanism 31 becomes narrow, making it difficult to incorporate components that hold scanning mechanism 31 and components that drive scanning mechanism 31. Setting the lower limit of conditional expression (7) to 0.72 can further ensure the effects of this embodiment.

[0042] The scanning optical system SL according to this embodiment may satisfy the following conditional expression (8). 0.5<(Σtc) / LA<0.9 (8) where Σtc: the sum of tc of lenses in multiple lens components

[0043] Conditional expression (8) defines an appropriate relationship between the sum of the lens center thicknesses (tc) of multiple lens components 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. Satisfying conditional expression (8) reduces the sum of the lens center thicknesses, thereby shortening the optical path length of light passing through the lenses. This reduces the group delay dispersion (GDD), making it possible to generate multiphoton excitation with high excitation efficiency and obtain bright images.

[0044] If the value corresponding to conditional expression (8) exceeds the upper limit, the total center thickness of the lens increases, and the optical path length of the light passing through the lens becomes longer. This increases the group delay dispersion (GDD), making it difficult to generate multiphoton excitation with high excitation efficiency and obtain a bright image. By setting the upper limit of conditional expression (8) to 0.85, 0.8, or even 0.75, the effect of this embodiment can be further ensured.

[0045] If the corresponding value of conditional expression (8) falls below the lower limit, the total center thickness of the lens becomes too small, making it difficult to correct aberrations such as field curvature and astigmatism. By setting the lower limit of conditional expression (8) to 0.6, or even 0.65, the effect of this embodiment can be further ensured.

[0046] In the scanning optical system SL according to this embodiment, the multiple lens components may include a first lens component, a second lens component, a third lens component, and a fourth lens component arranged in this order from the scanning mechanism 31 (pupil conjugate plane P) side 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: air gap on the optical axis between the second lens component and the third lens component D3: Air gap on the optical axis between the third and fourth lens components TL: the distance on the optical axis between the pupil conjugate plane P located on the scanning mechanism side of the scanning optical system SL and the image plane I located on the objective optical system side of the scanning optical system SL

[0047] Conditional formula (9) defines an appropriate relationship between the air gap on the optical axis between the third and fourth lens components and the air gap on the optical axis between the second and third lens components. Conditional formula (10) defines an appropriate relationship between the air gap on the optical axis between the second and third lens components and the overall length of the scanning optical system SL, i.e., the distance on the optical axis between a pupil conjugate plane P located on the scanning mechanism side of the scanning optical system SL and an image plane I (image plane 13) located on the objective optical system side of the scanning optical system SL. Conditional formula (12) defines an appropriate relationship between the air gap on the optical axis between the third and fourth lens components and the distance on the optical axis between a pupil conjugate plane P located on the scanning mechanism side of the scanning optical system SL and an image plane I (image plane 13) located on the objective optical system side of the scanning optical system SL. By satisfying the conditional expressions (9) to (11), the scanning optical system SL approaches telecentricity with respect to the image plane 13 (primary image plane), making it possible to correct astigmatism favorably.

[0048] If the value corresponding to conditional expression (9) is outside the above range, the scanning optical system SL cannot be made close to telecentric, making it difficult to correct astigmatism. By setting the upper limit of conditional expression (9) to 0.9, 0.8, or even 0.75, the effect of this embodiment can be made more certain. By setting the lower limit of conditional expression (9) to 0.1, 0.2, or even 0.25, the effect of this 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 close to telecentric, making it difficult to correct astigmatism. By setting the upper limit of conditional expression (10) to 0.1, or even 0.09, the effect of this embodiment can be made more certain. By setting the lower limit of conditional expression (10) to 0.044, the effect of this embodiment can be made more certain.

[0050] If the corresponding value of conditional expression (11) is outside the above range, the scanning optical system SL cannot be made close to telecentric, making it difficult to correct astigmatism. By setting the upper limit of conditional expression (11) to 0.04, the effect of this embodiment can be made more certain. By setting the lower limit 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 follows: nd×tc / νd of the lenses in a plurality of lens components 2 and the distance on the optical axis from the lens surface of the lens component closest to the scanning mechanism 31 on the scanning mechanism side to the lens surface of the lens component closest to the objective optical system 25 on the objective optical system side. Satisfying conditional expression (12) reduces the sum of the center thicknesses of the lenses, shortening the optical path length of light passing through the lenses and reducing group delay dispersion (GDD). Satisfying conditional expression (12) also reduces the reciprocal of the square of the Abbe number, i.e., the sum of the squares of the values indicating dispersion. This reduces the dispersion of the medium (lens) along the optical path and reducing group delay dispersion (GDD). Thus, satisfying conditional expression (12) reduces group delay dispersion (GDD), enabling multiphoton excitation with high excitation efficiency and the acquisition of bright images.

[0053] If the value corresponding to conditional expression (12) exceeds the upper limit, the total center thickness of the lens increases, and the optical path length of the light passing through the lens increases. This increases the group delay dispersion (GDD), making it difficult to generate multiphoton excitation with high excitation efficiency and obtain a bright image. By setting the upper limit of conditional expression (12) to 0.0004, 0.00035, or even 0.00033, the effect of this embodiment can be further ensured.

[0054] If the corresponding value of conditional expression (12) falls below the lower limit, the total center thickness of the lens becomes too small, making it difficult to correct aberrations such as field curvature and astigmatism. By setting the lower limit of conditional expression (12) to 0.00025, or even 0.00028, the effect of this embodiment can be further ensured. [Example]

[0055] Examples of the scanning optical system SL provided in the scanning microscope according to this embodiment will be described below with reference to the drawings. FIGS. 2, 6, 10, and 14 are cross-sectional views showing the configuration and refractive power distribution of the scanning optical systems SL {SL(1) to SL(4)} according to first to fourth examples. In FIGS. 2, 6, 10, and 14, each lens component is represented by a combination of a symbol E and a number, and each lens is represented by a combination of a symbol L and a number. In this case, to prevent the number and types of symbols and numbers from increasing and becoming complicated, lens components, etc. are represented by different combinations of symbols and numbers for each example. Therefore, even if the same combinations of symbols and numbers are used between examples, this does not necessarily mean that the examples have the same configuration.

[0056] Tables 1 to 4 are shown below, with Table 1 showing data on various elements in Example 1, Table 2 in Example 2, Table 3 in Example 3, and Table 4 in Example 4. In each example, the 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) were selected as the targets for calculating aberration characteristics.

[0057] In the [Overall Specifications] table, 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 total length of the scanning optical system (the distance on the optical axis between the pupil conjugate plane located on the scanning mechanism side of the scanning optical system and the image plane located on the objective optical system side of the scanning optical system).

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

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

[0060] θgF=(ng-nF) / (nF-nC) …(C)

[0061] The [Lens Component Data] table shows the starting surface (the surface closest to the object) and focal length of each lens component.

[0062] In the following, for all specifications, the focal length f, radius of curvature R, surface spacing D, and other lengths are generally expressed in "mm" unless otherwise specified, but this is not limited to this, as the same optical performance can be obtained even when the optical system is proportionally enlarged or reduced.

[0063] The explanation of the tables up to this point is common to all the embodiments, and duplicate explanations will be omitted below.

[0064] (First Example) 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 is composed of, arranged in order from the pupil conjugate plane P along the optical axis, a first lens component E1 having negative refractive power, a second lens component E2 having positive refractive power, a third lens component E3 having positive refractive power, a fourth lens component E4 having positive refractive power, and a fifth lens component E5 having negative refractive power. The above-mentioned scanning mechanism 31 (galvanometer mirror, etc.) is disposed near the pupil conjugate plane P, which is conjugate with the pupil plane of the objective optical system 25 (objective lens 24). The image plane I corresponds to the above-mentioned image plane 13. This also applies to all the following embodiments.

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

[0066] The following Table 1 shows the values of the specifications of the scanning optical system according to Example 1. Note that the first surface is the pupil conjugate surface 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 RD 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 Initial 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 Example 1. FIG. 4 is a diagram showing lateral chromatic aberration of magnification of the scanning optical system according to Example 1. FIG. 5 is a diagram showing coma aberrations (meridional coma and sagittal coma) of the scanning optical system according to Example 1. In each of the aberration diagrams in FIGS. 3 to 5, d indicates aberrations for the d-line (wavelength λ=587.6 nm), C indicates aberrations for the C-line (wavelength λ=656.3 nm), F indicates aberrations for the F-line (wavelength λ=486.1 nm), and g indicates aberrations for the g-line (wavelength λ=435.8 nm). In the spherical aberration diagrams, the vertical axis indicates values normalized with the maximum value of the entrance pupil radius set to 1, and the horizontal axis indicates the aberration value [mm] for each light ray. In the aberration diagrams showing field curvature, the solid line indicates the meridional image plane for each wavelength, and the dashed line indicates the sagittal image plane for each wavelength. In the aberration diagrams showing field curvature, the vertical axis indicates image height [mm], and the horizontal axis indicates aberration value [mm]. In the distortion diagrams, the vertical axis indicates image height [mm], and the horizontal axis indicates the aberration ratio as a percentage (% value). In the aberration diagrams showing lateral chromatic aberration, the vertical axis indicates image height [mm], and the horizontal axis indicates aberration value [mm]. Each coma aberration diagram shows the aberration value when the image height ratio RFH (Relative Field Height) is 0.00 and 1.00. Note that the same symbols as in this embodiment are used in the aberration diagrams of each embodiment shown below, and redundant explanations will be omitted.

[0069] From each aberration diagram, it can be seen that the scanning optical system according to Example 1 has excellent optical performance, with various aberrations including field curvature being well corrected.

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

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

[0072] The values of the specifications of the scanning optical system according to Example 2 are shown in Table 2 below. Note that the first surface is the pupil conjugate surface 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 RD 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 Initial 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 example. Fig. 8 is a diagram showing chromatic aberration of magnification (lateral chromatic aberration) of the scanning optical system according to the second example. Fig. 9 is a diagram showing coma aberrations (meridional coma aberration and sagittal coma aberration) of the scanning optical system according to the second example. It can be seen from each aberration diagram that the scanning optical system according to the second example has excellent optical performance, with various aberrations including field curvature being well corrected.

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

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

[0077] The values of the specifications of the scanning optical system according to Example 3 are shown in Table 3 below. Note that the first surface is the pupil conjugate surface 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 RD 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 Initial 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 Example 3. Fig. 12 is a diagram showing chromatic aberration of magnification (lateral chromatic aberration) of the scanning optical system according to Example 3. Fig. 13 is a diagram showing coma aberrations (meridional coma aberration and sagittal coma aberration) of the scanning optical system according to Example 3. It can be seen from each aberration diagram that the scanning optical system according to Example 3 has excellent optical performance with various aberrations including field curvature well corrected.

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

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

[0082] The values of the specifications of the scanning optical system according to Example 4 are shown in Table 4 below. 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 RD 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 Initial 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 Example 4. Fig. 16 is a diagram showing chromatic aberration of magnification (lateral chromatic aberration) of the scanning optical system according to Example 4. Fig. 17 is a diagram showing coma aberrations (meridional coma aberration and sagittal coma aberration) of the scanning optical system according to Example 4. It can be seen from each aberration diagram that the scanning optical system according to Example 4 has excellent optical performance with various aberrations including field curvature well corrected.

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

[0086] [Conditional expression corresponding value] Conditional Expression 1st Example 2nd Example 3rd Example 4th Example (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 the above-described embodiments, it is possible to realize a scanning optical system and a scanning microscope that can satisfactorily correct field curvature, astigmatism, and chromatic aberration of magnification, and can obtain bright images.

[0088] Here, the above examples show specific examples of this embodiment, and this embodiment is not limited to these.

[0089] In each of the above embodiments, the first lens component E1 and the third lens component E3 are each composed of a single lens, but this is not limited to this and each may be composed of a single cemented lens made up of multiple lenses cemented together. The second lens component E2, the fourth lens component E4, and the fifth lens component E5 are each composed of a single cemented lens made up of multiple lenses cemented together, but this is not limited to this and each may be composed of a single lens. [Explanation of symbols]

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

Claims

1. a scanning mechanism that scans the sample with light from the light source; an objective optical system that focuses light from the scanning mechanism onto the sample; a scanning optical system that is provided between the scanning mechanism and the objective optical system and that guides light from the scanning mechanism to the objective optical system, the scanning optical system is made up of a plurality of lens components arranged along an optical axis and has a positive refractive power as a whole; the lens component is composed of a cemented lens composed of a plurality of lenses cemented together, or a single lens; a lens surface of the lens component closest to the scanning mechanism among the plurality of lens components is concave, a lens surface of the lens component closest to the objective optical system among the plurality of lens components that faces the objective optical system is concave; A scanning microscope that satisfies the following conditional expression: 0.007<Σ(nd×tc / νd) / LA<0.021 where Σ(nd×tc / νd): the sum of nd×tc / νd of the lenses in the plurality of lens components, where nd is the refractive index of the lenses with respect to the d line, tc is the center thickness of the lenses, and νd is the Abbe number of the lenses. LA: the distance on the optical axis from the lens surface of the lens component closest to the scanning mechanism on the scanning mechanism side to the lens surface of the lens component closest to the objective optical system on the objective optical system side

2. 2. The scanning microscope according to claim 1, wherein the following condition is satisfied: -3<(ndA-1) / rA×f<-0.6 0.5<(ndE-1) / rE×f<3 where ndA is the refractive index for the d-line of the lens that is closest to the scanning mechanism among the lenses that make up the plurality of lens components. rA: radius of curvature of the lens surface closest to the scanning mechanism on the side of the scanning mechanism ndE: refractive index at the d-line of the lens that is closest to the objective optical system among the lenses that make up the plurality of lens components rE: radius of curvature of the lens surface closest to the objective optical system, on the side of the objective optical system f: focal length of the scanning optical system

3. some of the plurality of lens components are composed of one positive lens, 2. The scanning microscope according to claim 1, wherein the following condition is satisfied: νdP<38 0.651<θgFP+(0.001682×νdP) where νdP is the Abbe number of the positive lens. θgFP: partial dispersion ratio of the positive lens, which is defined by the following formula, where ngP is the refractive index of the positive lens with respect to the g-line, nFP is the refractive index of the positive lens with respect to the F-line, and nCP is the refractive index of the positive lens with respect to the C-line. θgFP=(ngP-nFP) / (nFP-nCP)

4. 4. The scanning microscope according to claim 3, wherein the following condition is satisfied: 1<fP / f<5 where fP is the focal length of the positive lens. f: focal length of the scanning optical system

5. 2. The scanning microscope according to claim 1, wherein the following condition is satisfied: 0.7<D0 / f<1 where D0 is the distance on the optical axis between the scanning mechanism and the lens component closest to the scanning mechanism. f: focal length of the scanning optical system

6. 2. The scanning microscope according to claim 1, wherein the following condition is satisfied: 0.5<(Σtc) / LA<0.9 where Σtc: the sum of tc of the lenses in the plurality of lens components

7. the plurality of lens components include a first lens component, a second lens component, a third lens component, and a fourth lens component, which are arranged in order from the scanning mechanism side along an optical axis, 2. The scanning microscope according to claim 1, wherein the following condition is satisfied: 0<D3 / D2<1 0.04<D2 / TL<0.11 0.02<D3 / TL<0.05 where D2: air gap on the optical axis between the second lens component and the third lens component D3: Air gap 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

8. 2. The scanning microscope according to claim 1, wherein the following condition is satisfied: 0.00000214<Σ(νO×τc / νO 2 ) / <0.000420� However, Σ(nd×tc / νd 2 nd×tc / νd of the lenses in the plurality of lens components 2 the sum of

Images