Particle analysis device, particle analysis method, and optical measurement device

Abstract

A particle analysis device (100) comprises: a light source that emits excitation light (EL1) including light with wavelengths of 400 nm or less; a lens structure (41) that concentrates the excitation light (EL1) onto a predetermined position (51s) in a flow path (53); a detection unit (7) that detects light (FL) radiated from a particle (51) flowing through the predetermined position by the particle being excited by the excitation light (EL1); and a processing unit (120) that processes detection data acquired by the detection unit (7). The lens structure (41) comprises a plurality of lenses (411) arranged along the optical axis of the excitation light (EL1), and a lens frame (412) that holds the plurality of lenses (411), and the position within the lens frame (412) of at least one lens (G12) among the plurality of lenses (411) is determined by the one lens being brought into contact with a lens adjacent thereto.

Description

[Technical Field]

[0001] The present disclosure relates to a particle analysis device, a particle analysis method, and an optical measurement device. [Background technology]

[0002] Conventionally, optical measurement methods using flow cytometry have been used to analyze biological particles such as cells, microorganisms, and liposomes. A flow cytometer is a device for performing optical measurements using flow cytometry, which irradiates light onto particles flowing through a flow channel formed in a flow cell, microchip, or the like, and detects the fluorescence and scattered light emitted from each particle to perform analysis, etc.

[0003] Some flow cytometers have the ability to separate and collect only particles with specific properties based on analysis results, and devices specifically designed to separate cells are called "cell sorters." The cell sorter's main separation method is a droplet charging method, which separates particles by charging droplets containing particles (see, for example, Patent Document 1). In droplet charging devices, fluid discharged from a flow cell, microchip, or the like is converted into droplets, which are then given a positive (+) or negative (-) charge and collected in a designated container by changing the direction of travel using a deflection plate or the like. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-145213 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-127922 Summary of the Invention [Problem to be solved by the invention]

[0005] Optical measurement devices for fluorescence observation, such as flow cytometers, require an objective lens to focus the laser light, as they need to irradiate particles with a high-intensity laser light to excite them. The objective lens used in typical optical measurement devices for fluorescence observation, etc., is a lens structure made up of multiple lenses assembled together using an adhesive. This can lead to problems such as the adhesive being burned by the high-intensity laser light, or outgassing released from the adhesive and adhering to the lens surface being burned by the excitation light, deteriorating the optical properties of the objective lens.

[0006] In recent years, advances in reagent development have led to the use of lasers in the ultraviolet range with wavelengths shorter than 405 nm in flow cytometers. Generally, the shorter the wavelength, the more likely the adhesive burns, making the above problem more severe.

[0007] Furthermore, when an ultraviolet laser is used, the emitted fluorescence ranges from the ultraviolet region to the near-infrared region, so the chromatic aberration of the objective lens must also be corrected over a wide band.

[0008] Furthermore, the optical glass used in objective lenses often has poor transmittance in the ultraviolet region. To correct chromatic aberration over a wide range, it is necessary to use multiple types of optical glass in a design, but this poses the problem of not being able to ensure sufficient transmittance due to absorption by the glass itself.

[0009] Therefore, the present disclosure proposes a particle analysis device, a particle analysis method, and an optical measurement device that are capable of suppressing deterioration of optical characteristics. [Means for solving the problem]

[0010] In order to solve the above problems, one form of particle analysis device according to the present disclosure comprises a light source that emits excitation light including light with a wavelength of 400 nm or less, a lens structure that focuses the excitation light at a predetermined position within a flow path, a detection unit that detects light emitted from particles flowing through the predetermined position when the particles are excited by the excitation light, and a processing unit that processes the detection data acquired by the detection unit, wherein the lens structure comprises a plurality of lenses arranged along the optical axis of the excitation light and a lens frame that holds the plurality of lenses, and the position of at least one of the plurality of lenses within the lens frame is determined by abutting against a lens adjacent to that lens.

[0011] A particle analysis method according to one embodiment of the present disclosure includes using a lens structure to focus excitation light containing light with a wavelength of 400 nm or less at a predetermined position in a flow path, detecting light emitted from particles flowing through the predetermined position as a result of the particles being excited by the excitation light, and processing the detection data, wherein the lens structure includes a plurality of lenses arranged along the optical axis of the excitation light and a lens frame that holds the plurality of lenses, and the position of at least one of the plurality of lenses within the lens frame is determined by abutting against a lens adjacent to the lens.

[0012] An optical measurement device according to one embodiment of the present disclosure includes a light source that emits excitation light including light with a wavelength of 400 nm or less, a lens structure that focuses the excitation light at a predetermined position within a flow path, and a detection unit that detects light emitted from particles flowing through the predetermined position when the particles are excited by the excitation light, wherein the lens structure includes a plurality of lenses arranged along the optical axis of the excitation light and a lens frame that holds the plurality of lenses, and the position of at least one of the plurality of lenses within the lens frame is determined by abutting against a lens adjacent to the lens. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a diagram illustrating an example of a schematic configuration of an optical measurement device according to an embodiment, and a particle analysis device including the optical measurement device; [Figure 2]FIG. 1 is a diagram showing an example of a schematic configuration of a microchip. [Figure 3] FIG. 2 is a diagram showing an example of a schematic configuration of a lens structure according to a first embodiment and a first example; [Figure 4] FIG. 2 is a diagram showing an example of a schematic configuration of a lens structure according to a first embodiment and a first example; [Figure 5] FIG. 2 is a diagram showing an example of a lens design of the first embodiment and first example. [Figure 6] FIG. 2 is a diagram showing an example of a schematic configuration of a lens structure according to the first embodiment and a second example; [Figure 7] FIG. 2 is a diagram showing an example of a schematic configuration of a lens structure according to the first embodiment and a second example; [Figure 8] FIG. 2 is a diagram showing an example of a lens design according to the first embodiment and a second example. [Figure 9] FIG. 2 is a diagram showing an example of a schematic configuration of a lens structure according to the first embodiment and a third example; [Figure 10] FIG. 2 is a diagram showing an example of a schematic configuration of a lens structure according to the first embodiment and a third example; [Figure 11] FIG. 10 is a diagram showing an example of a lens design according to the first embodiment and a third example. [Figure 12] FIG. 10 is a diagram showing an example of a schematic configuration of a lens structure according to the first embodiment and a fourth example. [Figure 13] FIG. 10 is a diagram showing an example of a schematic configuration of a lens structure according to the first embodiment and a fourth example. [Figure 14] FIG. 10 is a diagram showing an example of a lens design according to the first embodiment and a fourth example. [Figure 15] FIG. 10 is a diagram showing an example of a schematic configuration of a lens structure according to a second embodiment and a fifth example. [Figure 16] FIG. 10 is a diagram showing an example of a schematic configuration of a lens structure according to a second embodiment and a fifth example. [Figure 17] FIG. 10 is a diagram showing an example of a lens design according to the second embodiment and a fifth example. [Figure 18] FIG. 10 is a diagram showing an example of a schematic configuration of another lens structure according to the second embodiment. [Figure 19]FIG. 10 is a diagram showing an example of a schematic configuration of another lens structure according to the second embodiment. [Figure 20] 3 is a flowchart showing an example of a process (particle analysis method) executed in the particle analysis device. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the drawings. In the following embodiment, the same elements are designated by the same reference numerals, and redundant description will be omitted.

[0015] The present disclosure will be described in the following order. 1. Embodiment 1.1. Example of the first design condition for the lens structure 1.2. Example of the second design condition for the lens structure 1.3. Example of the third design condition for lens structure 1.4. Example of the fourth design condition for lens structure 1.5. Example of the fifth design condition for lens structure 1.6. Example of the sixth design condition for lens structure 1.7. Lens structure of the first embodiment and first example 1.8. Lens structure of the first embodiment and second example 1.9. Lens structure of the first embodiment and third example 1.10. Lens structure of the first embodiment and fourth example 1.11. Lens structure of the second embodiment and fifth example 1.12. Another example of lens structure for the second embodiment 2. Variations 3.Example of effects

[0016] 1. Embodiment The optical measurement device exemplified in the embodiments is an open-type cell sorter. However, the disclosed technology is also applicable to closed-type cell sorters. In the embodiments, a microchip method is used as an example of a method for supplying particles (microparticles) to an observation point (hereinafter also referred to as a "spot") on a flow path. However, various methods other than the microchip method, such as a droplet method, a cuvette method, and a flow cell method, may be adopted. In addition to cell sorters, the disclosed technology is applicable to various optical measurement devices that measure particles passing through spots set on a flow path, such as an analyzer-type flow cytometer and a microscope that acquires images of particles on a flow path.

[0017] FIG. 1 is a diagram showing an example of the schematic configuration of an optical measurement device according to an embodiment, and a particle analysis device including the optical measurement device. The particle analysis device 100 includes an optical measurement device 110 and a processing control unit 120. The particle analysis device 100 includes a light source 1, a mirror group 2, a mirror 3, an objective lens 4, a microchip 5, an imaging lens 6, a detection unit 7, and a detection unit 8. In the figure, a Z axis corresponding to the direction of the objective lens 4 is shown. The positive direction of the Z axis corresponds to the direction from the microchip 5 toward the mirror 3 (the traveling direction of scattered light BSC, etc., described below). The negative direction of the Z axis corresponds to the direction from the mirror 3 toward the microchip 5 (the traveling direction of excitation light EL1, etc., described below).

[0018] The optical measurement device 110 measures a test object located at a predetermined position in a flow channel in the microchip 5. In this example, a particle 51 located at a spot 51s is measured as the test object. The optical measurement device 110 irradiates the particle 51 with excitation light and detects light emitted from the particle 51. Hereinafter, the irradiation of excitation light will be described with reference to FIG. 1A, and the light detection will be described with reference to FIG. 1B.

[0019] Referring to FIG. 1A, the light source 1 emits excitation light, which is light for exciting the particle 51. The excitation light may be coherent light such as a laser or a beam. The excitation light may be pulsed light. The light source 1 emits excitation light including light with a wavelength in the ultraviolet region. The light in the ultraviolet region here may be light with a wavelength of 400 nm or less, or more specifically, light with a wavelength of 350 nm or less. The light source 1 emits the excitation light in accordance with a signal Sig3 from the processing control unit 120, which will be described later. As a result, the excitation light is irradiated onto the particle 51 at the timing when the particle 51 is positioned at the spot 51s.

[0020] The light source 1 may emit multiple excitation lights. In this example, the light source 1 includes light source 11 to light source 15. Light source 11 emits excitation light with a wavelength of 349 nm. Light source 12 outputs excitation light with a wavelength of 405 nm. Light source 13 emits excitation light with a wavelength of 488 nm. Light source 14 emits excitation light with a wavelength of 561 nm. Light source 15 emits excitation light with a wavelength of 637 nm. An example of the output level of the excitation light is several mW to several tens of mW. The excitation lights emitted by light source 11 to light source 15 are referred to as excitation light EL1 to excitation light EL5 and are illustrated. Hereinafter, excitation light EL1 to excitation light EL5 may be collectively referred to as "excitation light EL1, etc."

[0021] The mirror group 2 guides the excitation light EL1 and the like from the light source 1 toward the center 31 of the mirror 3, for example, by aligning (combining) their optical axes. Specifically, in this example, the mirror group 2 includes mirrors 21 to 25. The mirror 21 reflects the excitation light EL1 from the light source 11 toward the center 31 of the mirror 3. The mirror 22 transmits the excitation light EL1 from the mirror 21 and reflects the excitation light EL2 from the light source 12 toward the center 31 of the mirror 3. The mirror 23 transmits the excitation light EL1 and the excitation light EL2 from the mirror 22 and reflects the excitation light EL3 from the light source 13 toward the center 31 of the mirror 3. The mirror 24 transmits the excitation light EL1 to the excitation light EL3 from the mirror 23 and reflects the excitation light EL4 from the light source 14 toward the center 31 of the mirror 3. Mirror 25 transmits excitation light EL1 to EL4 from mirror 24 and reflects excitation light EL5 from light source 15 toward center portion 31 of mirror 3. Mirror 21 is, for example, a total reflection mirror. Mirrors 22 to 25 are, for example, dichroic mirrors.

[0022] The mirror 3 is an area-divided mirror whose area is divided into a central portion 31 and a peripheral portion 32. The mirror 3 is an optical system that guides the excitation light EL1 and other light incident on the central portion 31 from the mirror group 2 to the objective lens 4, and reflects the excitation light EL1 and other light toward the objective lens 4. The mirror 3 is disposed between the light source 1 (more specifically, the mirror group 2), the objective lens 4, and the detection unit 7 (more specifically, the imaging lens 6) so that the excitation light EL1 and other light from the mirror group 2 is incident at an incident angle of 45°, for example.

[0023] The objective lens 4 focuses the excitation light EL1 and the like from the mirror 3 onto a spot 51s within the microchip 5. Details of the objective lens 4 will be described later with reference to FIG. 3 and subsequent figures.

[0024] The microchip 5 provides a test object to be measured by the optical measurement device 110. The microchip 5 will be described with reference to FIG.

[0025] 2 is a diagram showing an example of a schematic configuration of a microchip. The microchip 5 includes a flow channel 53 through which particles 51 flow. In this example, the particles 51 are biological particles contained in a biological sample 52. The flow channel 53 is configured so that the biological sample 52, particularly the particles 51, flow substantially in a line. The biological sample 52 and the flow channel structure containing it may be made of a material such as plastic or glass.

[0026] The biological sample 52 is, for example, a cell or a non-cellular biological particle. The cell may be a living cell, and more specific examples include blood cells such as red blood cells and white blood cells, and reproductive cells such as sperm and fertilized eggs. The cell may be directly collected from a specimen such as whole blood, or may be a cultured cell obtained after culturing. Examples of non-cellular biological particles include extracellular vesicles, particularly exosomes and microvesicles. The biological particle may be labeled with one or more labeling substances (e.g., a dye (particularly a fluorescent dye) and a fluorescent dye-labeled antibody, etc.). Note that the optical measurement device may also analyze particles other than biological particles, and beads, etc. may be analyzed for calibration, etc.

[0027] 1A, excitation light EL1 and the like collected by the objective lens 4 is irradiated onto particles 51, exciting the particles 51. Fluorescence is generated due to the excitation of the particles 51. Furthermore, scattered light is generated due to the excitation light EL1 and the like being scattered by the particles 51.

[0028] 1(B), of the fluorescence generated by the particle 51, the fluorescence that travels toward the objective lens 4 (toward the positive direction of the Z axis) is referred to as fluorescence FL and is illustrated. Of the scattered light generated by the particle 51, the fluorescence that travels in the same direction as the excitation light EL1 is referred to as scattered light BSC (backward scattered light) and is illustrated. Of the scattered light generated by the particle 51, the scattered light that travels toward the opposite side of the objective lens 4 (toward the negative direction of the Z axis) is referred to as scattered light FSC (forward scattered light) and is illustrated.

[0029] The objective lens 4 , for example, collects the fluorescence FL and scattered light BSC from the microchip 5 and directs at least a portion of the light to the peripheral portion 32 of the mirror 3 .

[0030] The mirror 3 transmits the fluorescence FL and scattered light BSC from the objective lens 4 that are incident on the peripheral portion 32, and guides them to the imaging lens 6. As mentioned above, the mirror 3 also has the function of reflecting the excitation light EL1 and other light that are incident on the central portion 31 from the mirror group 2 toward the objective lens 4. The central portion 31 of the mirror 3 reflects light in wavelength bands such as the excitation light EL1, for example, in the case of a 45° incidence, and transmits light in other wavelength bands. The central portion 31 is, for example, a portion on which a dichroic mirror coating is formed. The peripheral portion 32 of the mirror 3 constitutes, for example, the portion of the mirror 3 other than the central portion 31, and transmits the fluorescence FL and scattered light BSC. The peripheral portion 32 is, for example, a portion on which an anti-reflection coating is formed.

[0031] The imaging lens 6 focuses the fluorescence FL and scattered light BSC that have passed through the mirror 3 onto the detection unit 7. As explained above, the objective lens 4 can have the function of focusing the fluorescence FL and scattered light BSC, so the imaging lens 6 may work in cooperation with the objective lens 4 to focus the fluorescence FL and scattered light BSC.

[0032] The detection unit 7 detects the fluorescence FL and scattered light BSC from the imaging lens 6. For example, the detection unit 7 detects light of wavelengths in the wavelength band of 360 nm to 850 nm, excluding the wavelengths of the excitation light EL1, etc., as components of the fluorescence FL. The detection unit 7 detects light of the same wavelength as the wavelength of some of the excitation light, such as the excitation light EL1 (for example, the excitation light EL3 having a wavelength of 488 nm), as components of the scattered light BSC.

[0033] The detection unit 7 detects, for example, the amount of light (spectrum) for each wavelength. The detection unit 7 may be configured to include a spectroscopic optical system that separates incident light into wavelengths, a detector (two-dimensional image sensor, photodiode, etc.) that detects the amount of light for each wavelength, etc. The detection results obtained by the detection unit 7 are transmitted to the processing control unit 120 as detection data. A signal of the detection data transmitted from the detection unit 7 to the processing control unit 120 is illustrated and referred to as signal Sig1.

[0034] The detection unit 8 detects the scattered light FSC from the microchip 5. An example of the configuration of the detection unit 8 may be the same as the configuration of the detection unit 7 regarding the scattered light BSC. The detection results of the detection unit 8 are transmitted as detection data to the processing control unit 120. The signal of the detection data transmitted from the detection unit 8 to the processing control unit 120 is referred to as signal Sig2 and is illustrated in the figure.

[0035] The processing control unit 120 functions as a processing unit that processes detection data (signal Sig1) from the detection unit 7. An example of this processing is analysis processing of the particles 51. For example, the processing control unit 120 analyzes the components, size, etc. of the particles 51 by evaluating the spectrum of the fluorescence FL. A spectral image, evaluation results, etc. may be presented to the user. When detecting scattered light BSC, it is desirable to block light with a small scattering angle using a mask or the like and transmit light with a large scattering angle for detection.

[0036] The processing control unit 120 also functions as a control unit that controls the light source 1 based on the detection data (signal Sig2) from the detection unit 8. Specifically, the processing control unit 120 identifies the timing at which the next particle 51 will pass through the spot 51s on the microchip 5 based on the detection data from the detection unit 8, and controls the light source 1 so that the next particle 51 is irradiated with excitation light EL1, etc. at that timing. A signal (control signal) for controlling the light source 1 is generated as signal Sig3 and transmitted from the processing control unit 120 to the light source 1. As described above, the light source 1 emits excitation light EL, etc. in accordance with the signal Sig3.

[0037] In the particle analysis device 100 and optical measurement device 110 described above, for example, a high-intensity laser beam for exciting particles 51 passes through objective lens 4. As will be described later, objective lens 4 includes multiple lenses. If an adhesive is used to assemble the lenses, the laser beam may burn the adhesive and even outgassing the adhesive that has adhered to the lens surface, potentially resulting in degradation of the optical characteristics. In particular, the above-mentioned problem becomes more apparent as the wavelength of the excitation light becomes shorter, i.e., when excitation light with a wavelength in the ultraviolet region of 400 nm or less, such as excitation light EL1, is used.

[0038] The fluorescent light FL also passes through the objective lens 4. Because the wavelength range of the fluorescent light FL is wide, spanning, for example, from the ultraviolet region to the near-infrared region, the chromatic aberration of the objective lens 4 must also be corrected over a broadband. Many optical glasses used in lenses have poor transmittance characteristics in the ultraviolet region. Correcting chromatic aberration over a broadband requires a design that uses multiple types of optical glass, but this poses the problem of not being able to ensure sufficient transmittance characteristics due to absorption by the glass itself.

[0039] The objective lens 4 has a lens structure designed to address at least some of the issues described above. The lens structure includes a plurality of lenses arranged (disposed) along the optical axis of the excitation light EL1 or the like (along the Z-axis direction), and a lens frame that holds the plurality of lenses. Some examples of design conditions for the lens structure will be described below. The lens structure is designed to satisfy one or more design conditions.

[0040] 1.1. Example of the first design condition for the lens structure The lens frame may hold multiple lenses within the lens frame without using adhesive. The position of at least one of the multiple lenses within the lens frame may be determined by abutting against an adjacent lens. Adjacent lenses form a joint division group. Multiple joint division groups may be formed, and in that case, the relative positions between the joint division surfaces are fixed without using adhesive.

[0041] By satisfying the first design condition, the inside of the lens frame has an adhesive-free structure, which makes it possible to prevent problems such as adhesive burning and burning of outgassing released from the adhesive and adhering to the lens surface. For example, it is possible to prevent deterioration of the optical characteristics of the lenses that make up the cemented split groups. By using cemented split groups, it is possible to effectively correct axial chromatic aberration while preventing the optical system from becoming larger and more expensive. This effect becomes more pronounced as the number of cemented split groups increases. There is also an increased possibility of reducing costs by reducing the number of parts and simplifying the assembly process.

[0042] 1.2. Example of the second design condition for the lens structure The lens structure may have a positive lens closest to the object to be inspected (negative Z-axis direction). The glass material of the positive lens may satisfy the following (1) and (2): (1) 1.73 <nd<1.83 (2)45<νd (2) nd is the refractive index at the d line, and νd is the Abbe number at the d line.

[0043] By satisfying the second design condition, transmittance in the ultraviolet region can be ensured and chromatic aberration can be corrected over a wide band. For example, if nd is below the lower limit of (1) above, the curvature of the positive lens becomes too sharp, degrading performance and making manufacturing difficult. If nd exceeds the upper limit of (1) above, transmittance of the glass for ultraviolet light decreases, reducing the intensity of the laser light (excitation light EL1, etc.) irradiated onto the particles 51 and causing problems such as autofluorescence. If νd is below the lower limit of (2) above, transmittance of the glass for ultraviolet light decreases, reducing the intensity of the laser light irradiated onto the particles 51 and causing problems such as autofluorescence.

[0044] 1.3. Example of the third design condition for lens structure The lens structure may have at least three or more positive lenses. These positive lenses may be different from the positive lens closest to the object (negative Z-axis direction) in the second design condition described above. The glass material of the three or more positive lenses may satisfy the following (3) to (5). (3)nd<1.52 (4)79<νd (5) PgF<0.54 PgF is the partial dispersion ratio between the g and F lines.

[0045] By satisfying the third design condition, transmittance in the ultraviolet region can be ensured and chromatic aberration can be corrected over a wide band. If nd exceeds the upper limit of (3) above, the transmittance of the glass for ultraviolet light decreases, the intensity of the laser light irradiating the particles 51 decreases, and problems such as autofluorescence occur. If νd falls below the lower limit of (4) above, chromatic aberration worsens. If PgF exceeds the upper limit of (5) above, chromatic aberration in the ultraviolet region worsens.

[0046] 1.4. Example of the fourth design condition for lens structure The lens structure may have at least two or more negative lenses, and the glass material of these negative lenses may satisfy the following (6) and (7): (6)nd<1.78 (7)29<νd

[0047] By satisfying the fourth design condition, transmittance in the ultraviolet region can be ensured and chromatic aberration can be corrected over a wide band. If nd exceeds the upper limit of (6) above, transmittance of the glass for ultraviolet rays will decrease. If νd is below the lower limit of (7) above, transmittance of the glass for ultraviolet rays will decrease.

[0048] 1.5. Example of the fifth design condition for lens structure The plurality of lenses may have a retrofocus configuration (reverse telephoto configuration). The plurality of lenses may be configured with a front lens group having negative refractive power or substantially no power, and a rear lens group having positive refractive power, arranged in order from the side where the excitation light EL1 etc. is incident to the side where it is emitted (towards the negative direction of the Z axis). The fact that the power is substantially no power means that the negative refractive power is such that it does not have a significant effect on the diffusion and concentration of light. force or positive refraction forceThe outer shape of the lenses constituting the front lens group may be substantially larger in the negative direction of the Z axis. The outer shape of the lenses constituting the front lens group may be substantially larger in the negative direction of the Z axis. The outer shape of the lenses may be the same as that of the adjacent lenses. The outer shape of the lenses constituting the rear lens group may be substantially smaller in the negative direction of the Z axis. The outer shape of the lenses may be the same as that of the adjacent lenses. The multiple lenses may satisfy the following (8) and (9). (8)-0.24 <ft / f1<0.08 (9) 0.35 <ft / f2<0.7 ft is the focal length of the entire lens system. f1 is the focal length of the front lens group. f2 is the focal length of the rear lens group.

[0049] By satisfying the fifth design condition, the focal length of the objective lens can be shortened compared to, for example, a telephoto configuration. If ft / f1 falls below the lower limit of (8) above, the negative power becomes too strong, resulting in poor performance. If ft / f1 exceeds the upper limit of (8) above or if ft / f2 falls below the lower limit of (9) above, the focal length cannot be shortened. If ft / f2 exceeds the upper limit of (9) above, the positive power becomes too strong, resulting in poor performance.

[0050] 1.6. Example of the sixth design condition for lens structure The multiple lenses may have a telephoto configuration. The outer dimensions of the multiple lenses are substantially smaller from the side where the excitation light EL1, etc., is incident to the side where it is emitted (negative direction of the Z axis). This increases the possibility of reducing the number of lenses and reducing costs compared to a retrofocus configuration (reverse telephoto configuration). In addition, for example, multiple lenses can be fitted and held in a single lens frame, which also reduces the cost of mechanical components.

[0051] The above first to sixth design conditions are merely examples, and various other design conditions may exist that will appear in the embodiments and examples of the lens structure described below. Taking the above into consideration, several embodiments and examples of the lens structure will be described. The two embodiments described are a first embodiment and a second embodiment. These embodiments differ in particular in that the first embodiment has a retrofocus configuration (corresponding to the fifth design condition), while the second embodiment has a telephoto configuration (corresponding to the sixth design condition).

[0052] 1.7. Lens structure of the first embodiment and first example Fig. 3 is a diagram showing an example of the schematic configuration of the lens structure of the first embodiment and first example. Fig. 3 shows an example of the cross-sectional structure when the lens structure is cut along a plane including the optical axis of the excitation light EL1, etc. The illustrated lens structure 41 includes multiple lenses 411, a lens frame 412, a fixing member 413, and an aperture stop 414. The focal length is 5 mm, the number of lenses is 8, the numerical aperture NA is 0.85, and the objective field of view φ is 0.6 mm.

[0053] The multiple lenses 411 are arranged along the optical axis (Z-axis direction) of the excitation light EL1 etc. In this example, the multiple lenses 411 include lenses G11 to G18 arranged in order in the negative Z-axis direction. Lenses G11 to G13 make up a front lens group 411F arranged on the positive Z-axis side. Lenses G14 to G18 make up a rear lens group 411R arranged on the negative Z-axis side.

[0054] The front lens group 411F and the rear lens group 411R are configured to provide a retrofocus configuration. Specifically, when viewed along the negative Z-axis direction, the front lens group 411F has a negative refractive power. force The rear lens group 411R has a positive refractive power or has substantially no power. force The outer shapes of the lenses G11 to G13 constituting the front lens group 411F may substantially increase in size in the negative direction of the Z axis. The outer shapes of the lenses G14 to G18 constituting the rear lens group 411R may substantially decrease in size in the negative direction of the Z axis.

[0055] Some adjacent lenses abut each other to form a cemented split group (marginal contact). In this example, lenses G12 and G13 form a cemented split group. Lenses G15 and G16 form a cemented split group.

[0056] The lens frame 412 is a frame that holds multiple lenses 411. The lens frame 412 includes a front frame 412F and a rear frame 412R. The front frame 412F is a frame that forms the portion of the lens frame 412 on the positive side of the Z axis. The rear frame 412R is a frame that forms the portion of the lens frame 412 on the negative side of the Z axis. The lens frame 412 may have a barrel shape. In that case, the front frame 412F is a front barrel that forms the front portion of the barrel shape. The rear frame 412R is a rear barrel that forms the rear portion of the barrel shape.

[0057] Examples of materials for the lens frame 412 include metals such as aluminum and brass, alloys, etc. However, the material is not limited to these, and various materials may be used taking into consideration price, ease of processing, durability, etc.

[0058] The lens frame 412 has a structure suitable for accommodating (fitting) and positioning the lens, etc. Several characteristic parts of the lens frame 412 are shown with reference numerals.

[0059] The front frame 412F includes an opening 412Fa, an opening 412Fb, a protrusion 412Fc, and a protrusion 412Fd. The opening 412Fa opens at the end of the front frame 412F in the positive Z-axis direction. The opening 412Fb opens at the end of the front frame 412F in the negative Z-axis direction. The protrusions 412Fc and 412Fd protrude toward the inside of the front frame 412F between the lenses G11 and G12. The lens G11 abuts against the protrusion 412Fc, and the lens G12 abuts against the protrusion 412Fd.

[0060] The rear frame 412R includes an opening 412Ra, an opening 412Rb, a protrusion 412Rc, and a protrusion 412Rd. The opening 412Ra opens at the end of the rear frame 412R in the positive direction of the Z axis. The opening 412Rb opens at the end of the rear frame 412R in the negative direction of the Z axis. The protrusions 412Rc and 412Rd protrude toward the inside of the rear frame 412R between the lenses G17 and G18. The lens G17 abuts against the protrusion 412Rc, and the lens G18 abuts against the protrusion 412Rd.

[0061] Although not shown, the lens frame 412 may have air holes for releasing the air inside when the multiple lenses 411 are fitted into the lens frame 412 .

[0062] The fixing member 413 fixes the positions of the multiple lenses 411 so that the multiple lenses 411 are positioned within the lens frame 412. In this example, the fixing member 413 includes a screw N11, a screw N13, a screw N14, a ring RG1415, a ring RG1617, and an adhesive AD18. The ring RG1415 is arranged to provide a gap between the lens G14 and the lens G15. The ring RG1617 is arranged to provide a gap between the lens G16 and the lens G17.

[0063] Examples of materials for the screw N11 and ring RG1415 are metals such as aluminum and copper, alloys, etc. However, the materials are not limited to these, and various materials may be used taking into consideration price, ease of processing, durability, etc.

[0064] The lens G11 is positioned by a screw N11 and a protrusion 412Fc of the front frame 412F. The lens G11 is fitted into the front frame 412F through an opening 412Fa of the front frame 412F so that the edge of the lens G11 abuts against the protrusion 412Fc. The screw N11 presses (biases) the edge of the lens G11 against the protrusion 412Fc in the negative direction of the Z axis to fix the lens G11.

[0065] Lenses G12 and G13 are positioned by screws N13 and protrusions 412Fd of the front frame 412F. Lenses G12 and G13 are fitted into the front frame 412F through openings 412Fb of the front frame 412F so that the edge of lens G12 abuts against the protrusions 412Fd. Screws N13 press the edges of lenses G13 and G12 against the protrusions 412Fd in the positive direction of the Z axis to secure them in place.

[0066] Lenses G14 to G17 are positioned by screws N14, rings RG1415 and RG1617, and protrusions 412Rc of rear frame 412R. Lenses G14 to G17, rings RG1415 and RG1617 are fitted into rear frame 412R through openings 412Ra of rear frame 412R so that the edge of lens G17 abuts against protrusions 412Rc. Screw N14 presses the edge of lens G14, the edges of ring RG1415, lenses G15 and G16, ring RG1617 and lens G17 against protrusions 412Rc in the negative direction of the Z axis to secure them in place.

[0067] The lens G18 is positioned by adhesive AD18 and the protrusion 412Rd of the rear frame 412R. The lens G18 is fitted into the rear frame 412R through the opening 412Rb of the rear frame 412R so that the edge of the lens G18 abuts against the protrusion 412Rd. The adhesive AD18 secures the lens G18 to the rear frame 412R on the outside of the rear frame 412R. Because the lens G18 is not sealed by the rear frame 412R, adhesive AD18 may be used. Note that, instead of using adhesive AD18, the lens G18 may be secured by pressing the edge of the lens G18 against the protrusion 412Rd in the negative direction of the Z axis using, for example, a cap with an opening in the center.

[0068] The rear frame 412R is fitted into the front frame 412F through the opening 412Fb of the front frame 412F, and the lens structure 41 in which the plurality of lenses 411 are positioned within the lens frame 412 is obtained.

[0069] The aperture stop 414 is provided between the front lens group 411F and the rear lens group 411R and adjusts the amount of light passing through. For example, the amount of light incident from the front lens group 411F to the rear lens group 411R is suppressed.

[0070] FIG. 4 is a diagram showing an example of the schematic configuration of the lens structure according to the first embodiment and the first example. In FIG. 4, some paths (optical paths) of light passing through the lens structure are schematically shown. As it travels in the negative Z-axis direction, the light generally diffuses in the front lens group 411F and generally converges in the rear lens group 411R. Therefore, the lens structure 41 converges the excitation light EL1 etc. to the spot 51s and also converges the fluorescence FL and the scattered light BSC toward the detection unit 7 (FIG. 1). The intensity of the excitation light EL1 etc. irradiated on the particle 51 is increased, and the light to be detected by the detection unit 7 is efficiently guided to the detection unit 7.

[0071] FIG. 5 is a diagram showing an example of the lens design according to the first embodiment and the first example. Convex indicates positive power and concave indicates negative power. A plurality of lenses 411 are designed so as to satisfy the above-described first design condition to fifth design condition.

[0072] Regarding the first design condition, the lens frame 412 holds a plurality of lenses 411 without using an adhesive within the lens frame 412. The adjacent lenses G12 and G13 constitute a joined split group whose positions within the lens frame 412 are determined by abutting. The adjacent lenses G15 and G16 also constitute a joined split group.

[0073] Regarding the second design condition, the lens G18 is the positive lens that is located closest to the particle 51 side and has positive power. The glass material of the lens G18 is nd = 1.8040 and νd = 46.5. Therefore, (1) 1.73 < nd < 1.83 and (2) 45 < νd are satisfied.

[0074] Regarding the third design condition, lenses G12, G14, G15, and G17 are positive lenses (three or more positive lenses). The glass materials of these lenses have nd = 1.4388, νd = 95.0, and PgF = 0.5340. Therefore, (3) nd < 1.52, (4) 79 < νd, and (5) PgF < 0.54 are satisfied.

[0075] Regarding the fourth design condition, lenses G11, G13, and G16 are negative lenses (two or more negative lenses). The glass material of lens G11 has nd = 1.4875 and νd = 70.2. The glass material of lens G13 has nd = 1.5891 and νd = 61.2. The glass material of lens G16 has nd = 1.7380 and νd = 32.3. Therefore, (6) nd < 1.78 and (7) 29 < νd are satisfied.

[0076] Regarding the fifth design condition, lenses G11 to G13 have negative refraction force or are a substantially non-power front lens group 411F. Lenses G14 to G18 are a rear lens group 411R having positive refraction force The focal length of the front lens group 411F (lenses G11 to G13) is f1 = -54.60 mm. The focal length of the rear lens group 411R (lenses G14 to G18) is f2 = 8.86 mm. The focal length of the entire plurality of lenses 411 (lenses G11 to G18) is ft = 5.00 mm. ft / f1 = -0.092. ft / f2 = 0.565. Therefore, (8) -0.24 < ft / f1 < 0.08 and (9) 0.35 < ft / f2 < 0.7 are satisfied.

[0077] 1.8. Lens Structure of the First Embodiment and the Second Example FIGS. 6 and 7 are diagrams showing an example of the schematic configuration of the lens structure of the first embodiment and the second example. The illustrated lens structure 42 includes a plurality of lenses 421, a lens frame 422, a fixing member 423, and an aperture stop 424. The focal length is 5 mm, the number of lenses is 8, the numerical aperture NA is 0.85, and the object field φ is 0.6 mm.

[0078] The lenses 421 include lenses G21 to G23 that make up a front lens group 421F and lenses G24 to G28 that make up a rear lens group 421R. Lenses G21 and G22 make up a cemented split group. Lenses G25 and G26 also make up a cemented split group.

[0079] The lens frame 422 includes a front frame 422F and a rear frame 422R. The front frame 422F includes an opening 422Fa, an opening 422Fb, a protrusion 422Fc, and a protrusion 422Fd. The rear frame 422R includes an opening 422Ra, an opening 422Rb, a protrusion 422Rc, and a protrusion 422Rc. The fixing member 423 includes screws N21, N23, N24, a ring RG2425, a ring RG2627, and an adhesive AD28. The ring RG2425 is disposed to provide a gap between the lenses G24 and G25. The ring RG2627 is disposed to provide a gap between the lenses G26 and G27. The aperture diaphragm 424 is disposed between the front lens group 421F and the rear lens group 421R and adjusts the amount of light passing through.

[0080] Lenses G21 and G22 are positioned by screws N21 and protrusions 422Fc of the front frame 422F. Lenses G21 and G22 are fitted into the front frame 422F through openings 422Fa of the front frame 422F so that the edges of lenses G22 abut against the protrusions 422Fc. Screws N21 are oriented in the negative direction of the Z axis to press the edges of lenses G21 and G22 against the protrusions 422Fc to secure them in place.

[0081] The lens G23 is positioned by a screw N23 and a protrusion 422Fd of the front frame 422F. The lens G23 is fitted into the front frame 422F through an opening 422Fb of the front frame 422F so that the edge of the lens G23 abuts against the protrusion 422Fd. The screw N23 presses the edge of the lens G23 against the protrusion 422Fd in the positive direction of the Z axis to secure the lens G23.

[0082] Lenses G24 to G27 are positioned by screws N24, rings RG2425 and RG2627, and protrusions 422Rc of rear frame 422R. Lenses G24 to G27, rings RG2425 and RG2627 are fitted into rear frame 422R through openings 422Ra of rear frame 422R so that the edge of lens G27 abuts against protrusions 422Rc. Screw N24 presses the edge of lens G24, the edges of ring RG2425, lenses G25 and G26, ring RG2627 and lens G27 against protrusions 422Rc in the negative direction of the Z axis to secure them in place.

[0083] The lens G28 is positioned by adhesive AD28 and protrusions 422Rd of the rear frame 422R. The lens G28 is fitted into the rear frame 422R through an opening 422Rb of the rear frame 422R so that the edge of the lens G28 abuts against the protrusions 422Rd. The adhesive AD28 fixes the lens G28 to the rear frame 422R on the outside of the rear frame 422R.

[0084] The rear frame 422R is fitted into the front frame 422F through the opening 422Fb of the front frame 422F, and the lens structure 42 in which the plurality of lenses 421 are positioned within the lens frame 422 is obtained.

[0085] As shown in FIG. 7, as the light travels in the negative direction of the Z axis, the light is generally diffused in front lens group 421F, and generally converged in rear lens group 421R.

[0086] 8 is a diagram showing an example of lens design of the first embodiment and example 2. A plurality of lenses 421 are designed so as to satisfy the first to fifth design conditions described above.

[0087] Regarding the first design condition, the lens frame 422 holds the multiple lenses 421 without using adhesive within the lens frame 422. Adjacent lenses G21 and G22 form a cemented split group whose position within the lens frame 422 is determined by their abutment. Adjacent lenses G25 and G26 also form a cemented split group.

[0088] Regarding the second design condition, lens G28 is a positive lens that is located closest to the particle 51 side and has a positive power. The glass material of lens G28 has nd = 1.8040 and νd = 46.5. Therefore, it satisfies (1) 1.73 < nd < 1.83 and (2) 45 < νd.

[0089] Regarding the third design condition, lenses G23, G24, G25, and G27 are positive lenses (three or more positive lenses). The glass materials of these lenses have nd = 1.4388, νd = 95.0, and PgF = 0.5340. Therefore, it satisfies (3) nd < 1.52, (4) 79 < νd, and (5) PgF < 0.54.

[0090] Regarding the fourth design condition, lenses G21 and G26 are negative lenses (two or more negative lenses). The glass material of lens G21 has nd = 1.4970 and νd = 81.6. The glass material of lens G26 has nd = 1.7380 and νd = 32.3. Therefore, it satisfies (6) nd < 1.78 and (7) 29 < νd.

[0091] Regarding the fifth design condition, lenses G21 to G23 are the front lens group 421F that has negative refraction force or is substantially a non-power front lens group. Lenses G24 to G28 are the rear lens group 421R that has positive refraction force The focal length of the front lens group 421F (lenses G21 to G23) is f1 = -46.08 mm. The focal length of the rear lens group 421R (lenses G24 to G28) is f2 = 8.18 mm. The focal length of the entire plurality of lenses 421 (lenses G21 to G28) is ft = 5.00 mm. ft / f1 = -0.109. ft / f2 = 0.611. Therefore, it satisfies (8) -0.24 < ft / f1 < 0.08 and (9) 0.35 < ft / f2 < 0.7.

[0092] 1.9. Lens structure of the first embodiment and the third example 9 and 10 are diagrams showing an example of the schematic configuration of the lens structure of the first embodiment and example 3. The illustrated lens structure 43 includes multiple lenses 431, a lens frame 432, a fixing member 433, and an aperture stop 434. The focal length is 5 mm, the number of lenses is 8, the numerical aperture NA is 0.85, and the objective field of view φ is 0.6 mm.

[0093] The multiple lenses 431 include lenses G31 and G32 that constitute a front lens group 431F, and lenses G33 to G38 that constitute a rear lens group 431R. The lenses G31 and G32 constitute a cemented split group. The lenses G33 and G34 also constitute a cemented split group. The lenses G36 and G37 also constitute a cemented split group.

[0094] The lens frame 432 includes a front frame 432F and a rear frame 432R. The front frame 432F includes an opening 432Fa, an opening 432Fb, and a protrusion 432Fd. The rear frame 432R includes an opening 432Ra, an opening 432Rb, a protrusion 432Rc, and a protrusion 432Rd. The fixing member 433 includes a screw N32, a screw N33, a ring RG3435, and a ring RG3536. The ring RG3435 is arranged to provide a gap between the lens G34 and the lens G35. The ring RG3536 is arranged to provide a gap between the lens G35 and the lens G36. The aperture diaphragm 434 is provided between the front lens group 431F and the rear lens group 431R and adjusts the amount of light passing through.

[0095] Lenses G31 and G32 are positioned by screws N32 and protrusions 432Fd of front frame 432F. Lenses G31 and G32 are fitted into front frame 432F through openings 432Fa of front frame 432F so that the edge of lens G31 abuts against protrusions 432Fd. Screws N32 press the edges of lenses G32 and G31 against protrusions 432Fd in the positive direction of the Z axis to secure them in place.

[0096] Lenses G33 to G37 are positioned by screw N33, rings RG3435 and RG3536, and protrusions 432Rc of rear frame 432R. Lenses G33 to G37, rings RG3435, and rings RG3536 are fitted into rear frame 432R through openings 432Ra of rear frame 432R so that the edge of lens G37 abuts against protrusions 432Rc. Screw N33 presses the edges of lenses G33 and G34, rings RG3435 and RG35, ring RG3536, and lenses G36 and G37 against protrusions 432Rc in the negative direction of the Z axis to secure them in place.

[0097] The lens G38 is positioned by a protrusion 432Rd of the rear frame 432R. The lens G38 is fitted into the rear frame 432R through an opening 432Rb of the rear frame 432R so that the edge of the lens G38 abuts against the protrusion 432Rd. Although not shown, the lens G38 may be fixed to the rear frame 432R on the outside of the rear frame 432R with an adhesive or the like.

[0098] The rear frame 432R is fitted into the front frame 432F through the opening 432Fb of the front frame 432F, and the lens structure 43 in which the plurality of lenses 431 are positioned within the lens frame 432 is obtained.

[0099] As shown in FIG. 10, as the light travels in the negative direction of the Z axis, the light is generally diffused in the front lens group 431F, and generally converged in the rear lens group 431R.

[0100] 11 is a diagram showing an example of lens design of the first embodiment and example 3. A plurality of lenses 431 are designed so as to satisfy the above-mentioned first to fifth design conditions.

[0101] Regarding the first design condition, the lens frame 432 holds the multiple lenses 431 without using adhesive within the lens frame 432. Adjacent lenses G31 and G32 form a cemented split group whose position within the lens frame 432 is determined by their abutment. Adjacent lenses G33, G34, G36, and G37 also form a cemented split group.

[0102] Regarding the second design condition, the lens G38 is the positive lens that is located closest to the particle 51 side and has a positive power. The glass material of the lens G38 has nd = 1.7550 and νd = 52.3. Therefore, it satisfies (1) 1.73 < nd < 1.83 and (2) 45 < νd.

[0103] Regarding the third design condition, the lenses G32, G33, G35, and G36 are positive lenses (three or more positive lenses). The glass materials of these lenses have nd = 1.4388, νd = 95.0, and PgF = 0.5340. Therefore, it satisfies (3) nd < 1.52, (4) 79 < νd, and (5) PgF < 0.54.

[0104] Regarding the fourth design condition, the lenses G31, G34, and G37 are negative lenses (two or more negative lenses). The glass materials of the lenses G31 and G34 have nd = 1.7550 and νd = 52.3. The glass material of the lens G37 has nd = 1.7380 and νd = 32.3. Therefore, it satisfies (6) nd < 1.78 and (7) 29 < νd.

[0105] Regarding the fifth design condition, the lenses G31 and G32 are the front lens group 431F that has negative refraction force or substantially non-power. The lenses G33 to G38 are the rear lens group 431R that has positive refraction force The focal length of the front lens group 431F (the lenses G31 and G32) is f1 = -31.49 mm. The focal length of the rear lens group 431R (the lenses G33 to G38) is f2 = 10.34 mm. The focal length of the entire plurality of lenses 431 (the lenses G31 to G38) is ft = 5.00 mm. ft / f1 = -0.159. ft / f2 = 0.483. Therefore, it satisfies (8) -0.24 < ft / f1 < 0.08 and (9) 0.35 < ft / f2 < 0.7.

[0106] 1.10. Lens structure of the first embodiment and the fourth example 12 and 13 are diagrams showing an example of the schematic configuration of the lens structure of the first embodiment and Example 4. The illustrated lens structure 44 includes multiple lenses 441, a lens frame 442, a fixing member 443, and an aperture stop 444. The focal length is 5 mm, the number of lenses is 9, the numerical aperture NA is 0.85, and the objective field of view φ is 0.6 mm.

[0107] The multiple lenses 441 include lenses G41 to G44 that constitute a front lens group 441F and lenses G45 to G49 that constitute a rear lens group 441R. Lenses G41 and G42 constitute a cemented split group. Lenses G43 and G44 also constitute a cemented split group. Lenses G45 and G46 also constitute a cemented split group. Lenses G47 and G48 also constitute a cemented split group.

[0108] The lens frame 442 includes a front frame 442F and a rear frame 442R. The front frame 442F includes an opening 442Fa, an opening 442Fb, and a protrusion 442Fd. The rear frame 442R includes an opening 442Ra, an opening 442Rb, a protrusion 442Rc, and a protrusion 442Rd. The fixing member 443 includes screws N42, N43, rings RG4445, RG4647, and adhesive AD49. The ring RG4445 is disposed to provide a gap between the lenses G44 and G45. The ring RG4647 is disposed to provide a gap between the lenses G46 and G47. The aperture diaphragm 444 is disposed between the front lens group 441F and the rear lens group 441R and adjusts the amount of light passing through.

[0109] Lenses G41 and G42 are positioned by screws N42 and protrusions 442Fd of front frame 442F. Lenses G41 and G42 are fitted into front frame 442F through openings 442Fb of front frame 442F so that the edge of lens G41 abuts against protrusions 442Fd. Screws N42 press the edges of lenses G42 and G41 against protrusions 442Fd in the positive direction of the Z axis to secure them in place.

[0110] Lenses G43 to G48 are positioned by screw N43, ring RG4445, ring RG4647, and protrusion 442Rc of rear frame 442R. Lenses G43 to G48, ring RG4445, and ring RG4647 are fitted into rear frame 442R through opening 442Ra of rear frame 442R so that the edge of lens G48 abuts on protrusion 442Rc. Screw N43 presses the edges of lenses G43 and G44, ring RG4445, lenses G45 and G46, ring RG4647, and lenses G47 and G48 against protrusion 442Rc in the negative direction of the Z axis to secure them in place.

[0111] The lens G49 is positioned by adhesive AD49 and protrusions 442Rd of the rear frame 442R. The lens G49 is fitted into the rear frame 442R through an opening 442Rb of the rear frame 442R so that the edge of the lens G49 abuts against the protrusions 442Rd. The adhesive AD49 fixes the lens G49 to the rear frame 442R on the outside of the rear frame 442R.

[0112] The rear frame 442R is fitted into the front frame 442F through the opening 442Fb of the front frame 442F, and the lens structure 44 in which the plurality of lenses 441 are positioned within the lens frame 442 is obtained.

[0113] As shown in FIG. 13, as the light travels in the negative direction of the Z axis, the light is generally diffused in the front lens group 441F, and generally converged in the rear lens group 441R.

[0114] 14 is a diagram showing an example of lens design of the first embodiment and Example 4. A plurality of lenses 441 are designed so as to satisfy the above-mentioned first to fourth design conditions.

[0115] Regarding the first design condition, the lens frame 442 holds a plurality of lenses 441 without using an adhesive within the lens frame 442. Adjacent lenses G41 and G42 form a joined split group whose positions within the lens frame 442 are determined by abutting against each other. Adjacent lenses G43 and G44, as well as G45 and G46, and lenses G47 and G48 also form joined split groups.

[0116] Regarding the second design condition, lens G49 is a positive lens with positive power and is located on the side closest to the particles 51. The glass material of lens G49 has nd = 1.7550 and νd = 52.3. Thus, it satisfies (1) 1.73 < nd < 1.83 and (2) 45 < νd.

[0117] Regarding the third design condition, lenses G42, G43, G45, and G47 are positive lenses (three or more positive lenses). The glass materials of these lenses have nd = 1.4388, νd = 95.0, and PgF = 0.5340. Thus, it satisfies (3) nd < 1.52, (4) 79 < νd, and (5) PgF < 0.54.

[0118] Regarding the fourth design condition, lenses G41, G44, G46, and G48 are negative lenses (two or more negative lenses). The glass materials of lenses G41, G44, and G46 have nd = 1.7550 and νd = 52.3. The glass material of lens G48 has nd = 1.7380 and νd = 32.3. Thus, it satisfies (6) nd < 1.78 and (7) 29 < νd.

[0119] Regarding the fifth design condition, lenses G41 to G44 are a front lens group 441F having negative refraction force or substantially non - power. Lenses G45 to G49 are a rear lens group having positive refraction forceIt is the rear lens group 441R having the following. The focal length of the front lens group 441F (lenses G41 to G44) is f1 = 1346.90 mm. The focal length of the rear lens group 441R (lenses G45 to G49) is f2 = 10.22 mm. The focal length of the entire plurality of lenses 441 (lenses G41 to G49) is ft = 5.00 mm. ft / f1 = 0.004. ft / f2 = 0.489. Therefore, (8) -0.24 < ft / f1 < 0.08 and (9) 0.35 < ft / f2 < 0.7 are satisfied.

[0120] 1.11. Lens Structure of the Second Embodiment and the Fifth Embodiment FIGS. 15 and 16 are diagrams showing an example of the schematic configuration of the lens structure of the second embodiment and the fifth embodiment. The illustrated lens structure 45 includes a plurality of lenses 451, a lens frame 452, a fixing member 453, and an aperture stop 454. The focal length is 10 mm, the number of lenses is 8, the numerical aperture NA is 0.85, and the object field φ is 0.6 mm.

[0121] The plurality of lenses 451 includes lenses G51 to G58. Lenses G53 and G54 constitute a joined and divided group. Lenses G56 and G57 also constitute a joined and divided group.

[0122] The lens frame 452 includes an opening 452a, an opening 452b, a protrusion 452c, and a protrusion 452d. The fixing member 453 includes a screw N51, rings RG5152, rings RG5253, rings RG5455, rings RG5556, and an adhesive AD58. The ring RG5152 is arranged to provide a gap between lenses G51 and G52. The ring RG5253 is arranged to provide a gap between lenses G52 and G53. The ring RG5455 is arranged to provide a gap between lenses G54 and G55. The ring RG5556 is arranged to provide a gap between lenses G55 and G56. The aperture stop 454 is provided between lenses G52 and G53 to adjust the amount of light passing through.

[0123] Lenses G51 to G57 are positioned by screw N51, rings RG5152, RG5253, rings RG5455, rings RG5556, and protrusion 452c of lens frame 452. Lenses G51 to G57, rings RG5152, RG5253, rings RG5455, and ring RG5556 are fitted into lens frame 452 through opening 452a of lens frame 452 so that the edge of lens G57 abuts against protrusion 452c. Screw N51 presses the edge of lens G51, ring RG5152, the edge of lens G52, ring RG5253, the edges of lenses G53 and G54, ring RG5455, the edge of lens G55, ring RG5556, and the edges of lenses G56 and G57 against protrusion 452c in the negative direction of the Z axis to secure them.

[0124] The lens G58 is positioned by the adhesive AD58 and the protrusion 452d of the lens frame 452. The lens G58 is fitted into the lens frame 452 through the opening 452b of the lens frame 452 so that the edge of the lens G58 abuts against the protrusion 452d. The adhesive AD58 fixes the lens G58 to the lens frame 452 on the outside of the lens frame 452.

[0125] The lens frame 452 is a single frame body, and by fitting and fixing as described above, a lens structure 45 in which a plurality of lenses 451 are positioned within the lens frame 452 is obtained.

[0126] As shown in FIG. 16, the light is generally focused by the lenses 451 as it travels in the negative direction of the Z axis.

[0127] 17 is a diagram showing an example of lens design of the second embodiment and example 5. A plurality of lenses 421 are designed so as to satisfy the above-mentioned first to fourth design conditions and sixth design condition.

[0128] Regarding the first design condition, the lens frame 452 holds a plurality of lenses 451 without using an adhesive within the lens frame 452. Adjacent lenses G53 and G54 form a bonded split group whose positions within the lens frame 452 are determined by abutting against each other. Adjacent lenses G56 and G57 also form a bonded split group.

[0129] Regarding the second design condition, lens G58 is the positive lens that is located on the side closest to the particle 51 and has positive power. The glass material of lens G58 has nd = 1.7550 and νd = 52.3. Therefore, it satisfies (1) 1.73 < nd < 1.83 and (2) 45 < νd.

[0130] Regarding the third design condition, lenses G53, G55, and G56 are positive lenses (three or more positive lenses) corresponding to the third design condition. The glass materials of these lenses have nd = 1.4388, νd = 95.0, and PgF = 0.5340. Therefore, it satisfies (3) nd < 1.52, (4) 79 < νd, and (5) PgF < 0.54.

[0131] Regarding the fourth design condition, lenses G51, G54, and G57 are negative lenses (two or more negative lenses). The glass material of lens G51 has nd = 1.5952 and νd = 67. The glass material of lens G54 has nd = 1.7550 and νd = 52.3. The glass material of lens G57 has nd = 1.7380 and νd = 32.3. Therefore, it satisfies (6) nd < 1.78 and (7) 29 < νd. <00,00506>

[0132] Regarding the sixth design condition, the outer shapes of the plurality of lenses 451 become smaller as they go from the side where the excitation light EL1 etc. is incident to the side where it exits (as they go in the negative Z-axis direction).

[0133] 1.12. Example of Another Lens Structure of the Second Embodiment 18 and 19 are diagrams showing an example of the schematic configuration of another lens structure of Embodiment 2. The illustrated lens structure 46 includes multiple lenses 461, a lens frame 462, and a fixing member 463. The focal length is 10 mm, the number of lenses is 6, the numerical aperture NA is 0.75, and the objective field of view φ is 0.5 mm.

[0134] The plurality of lenses 461 includes lenses G61 to G66. Lenses G62 and G63 form a cemented split group. Lenses G64 and G65 also form a cemented split group.

[0135] The lens frame 462 includes an opening 462a, an opening 462b, a protrusion 462c, a protrusion 462d, and air holes 462e, 462f, and 462g. The air holes 462e are holes for venting internal air when the lens G61 is fitted into the lens frame 462. The air holes 462f are holes for venting internal air when the lens G63 is fitted into the lens frame 462. The air holes 462g are holes for venting internal air when the lenses G65 and G66 are fitted into the lens frame 462. The fixing member 463 includes a screw N61, a ring RG6162, and a ring RG6364. The ring RG6162 is positioned to provide a gap between the lenses G61 and G62. Ring RG6364 is positioned to provide spacing between lens G63 and lens G64.

[0136] Lenses G61 to G65 are positioned by screw N61, rings RG6162, ring RG6364, and protrusion 462c of lens frame 462. Lenses G61 to G65, screw N61, rings RG6162, and ring RG6364 are fitted into lens frame 462 through opening 462a of lens frame 462 so that the edge of lens G65 abuts against protrusion 462c. Screw N61 presses the edge of lens G61, the edges of ring RG6162, lenses G62 and G63, ring RG6364, and lenses G64 and G65 against protrusion 462c in the negative direction of the Z axis to secure them in place.

[0137] The lens G66 is positioned by a protrusion 462d of the lens frame 462. The lens G66 is fitted into the lens frame 462 through an opening 462b of the lens frame 462 so that the edge of the lens G66 abuts against the protrusion 462d. Although not shown, the lens G66 may be fixed to the lens frame 462 with an adhesive or the like on the outside of the lens frame 462.

[0138] The lens frame 462 is a single frame body, and by fitting and fixing as described above, the lens structure 46 in which the plurality of lenses 461 are positioned within the lens frame 462 is obtained.

[0139] As shown in FIG. 19, the light is generally collected by the lenses 461 as it travels in the negative direction of the Z axis.

[0140] The lens structure 46 may also be designed to satisfy at least some of the first to fourth design conditions and the sixth design condition described above.

[0141] FIG. 20 is a flowchart showing an example of a process (particle analysis method) executed in the particle analysis device.

[0142] In step S1, excitation light is focused onto a spot using the lens structure. The light source 1 emits excitation light EL1 etc., and the objective lens 4 (lens structures 41 to 46) focuses the excitation light EL1 etc. onto the spot 51s. The particles 51 located at the spot 51s are excited and emit light such as fluorescence FL.

[0143] In step S2, the light emitted from the particles is detected. The detection unit 7 detects light such as fluorescence FL emitted from the particles 51 by the focused irradiation of the excitation light EL1 in the previous step S1.

[0144] In step S3, the detection data is processed. The processing control unit 120 processes the detection data obtained by the detection in the previous step S2, and analyzes, for example, the components, size, etc. of the particles 51.

[0145] 2. Variations Although the embodiments of the present disclosure have been described above, the disclosed technology is not limited to the above embodiments. Some modified examples will be described.

[0146] In the above embodiment, an open-type cell sorter has been described as an example of the optical measurement device 110 included in the particle analysis device 100. However, as mentioned at the beginning, the disclosed technology may also be applied to a closed-type cell sorter, an analyzer-type flow cytometer, a microscope that acquires images of particles in a flow channel, and the like.

[0147] In the above embodiment, a method using a microchip 5 (microchip method) has been described as an example of a method for supplying particles 51 to spots 51s. However, in addition to the microchip method, various methods such as a droplet method, a cuvette method, and a flow cell method may be adopted.

[0148] In the above embodiment, an example has been described in which the particles 51 are irradiated with excitation light EL1 (wavelength 349 nm), excitation light EL2 (wavelength 405 nm), excitation light EL3 (wavelength 488 nm), excitation light EL4 (wavelength 561 nm), and excitation light EL5 (wavelength 637 nm). However, the number and wavelengths of the excitation lights are not limited to this example. Various excitation lights (combinations) may be irradiated onto the particles 51 depending on the type of particle 51, the content of its analysis, etc.

[0149] In the above embodiment, the mirror group 2, the mirror 3, and the imaging lens 6 are used as examples of an optical system for guiding the excitation light EL1 and the like to the objective lens 4 and for guiding the scattered light BSC and the like from the objective lens 4 to the detection unit 7. However, the present invention is not limited to the mirror group 2, the mirror 3, and the imaging lens 6, and any optical system that can achieve a similar purpose may be used.

[0150] 3.Example of effects The technology described above is specified as follows, for example. As described with reference to FIGS. 1 and 3, etc., the particle analyzer 100 includes a light source 1 that emits excitation light EL1, etc. including light with a wavelength of 400 nm or less (it may be 350 nm or less) (and may also include light with a wavelength longer than 400 nm), a lens structure 41 (objective lens 4) that condenses the excitation light EL1, etc. at a predetermined position (spot 51s) in the flow path 53, a detection unit 7 that detects light (fluorescence FL and scattered light BSC) emitted from the particles 51 when the particles 51 flowing through the predetermined position are excited by the excitation light EL1, etc., and a processing unit (processing control unit 120) that processes the detection data acquired by the detection unit 7. The lens structure 41 includes a plurality of lenses 411 arranged along the optical axis of the excitation light EL1, etc. (along the negative Z-axis direction), and a lens frame 412 that holds the plurality of lenses 411. At least one of the plurality of lenses 411 (lenses G12, G13, G15, and G16) is positioned within the lens frame 412 by abutting against the adjacent lens.

[0151] According to the above particle analyzer 100, since the lenses constituting the joining and dividing group abut against each other and are positioned within the lens frame 412, the inside of the lens frame 412 can have an adhesive-free structure. Therefore, it is possible to prevent, for example, burning of the adhesive and burning of outgas adhering to the lens surface released from the adhesive, which may occur due to the excitation light in the ultraviolet region with a short wavelength such as 400 nm or less passing through the plurality of lenses 411. Thus, it is possible to suppress deterioration of the optical characteristics.

[0152] As described with reference to FIGS. 3 and 5, etc., the plurality of lenses 411 have a positive lens (lens G18) on the most object side (positive Z-axis direction side), and for the glass material of the positive lens, when the refractive index at the d-line is nd and the Abbe number at the d-line is νd, (1) 1.73 < nd < 1.83 and (2) 45 < νd may be satisfied. Thereby, it is possible to ensure the transmittance in the ultraviolet region and correct chromatic aberration in a wide band.

[0153] As described with reference to FIGS. 3 and FIG. 5 and the like, the plurality of lenses 411 have at least three or more positive lenses (lenses G12, G14, G15, and G17). For the glass materials of the three or more positive lenses, when the refractive index at the d-line is nd, the Abbe number at the d-line is νd, and the partial dispersion ratio between the g-line and the F-line is PgF, (3) nd < 1.52, (4) 79 < νd, and (5) PgF < 0.54 may be satisfied. Also by this, it is possible to ensure the transmittance in the ultraviolet region and correct chromatic aberration over a wide band.

[0154] As described with reference to FIGS. 3 and FIG. 5 and the like, the plurality of lenses 411 have at least two or more negative lenses (lenses G11, G13, and G16). For the glass materials of the two or more negative lenses, when the refractive index at the d-line is nd and the Abbe number at the d-line is νd, (6) nd < 1.78 and (7) 29 < νd may be satisfied. Also by this, it is possible to ensure the transmittance in the ultraviolet region and correct chromatic aberration over a wide band.

[0155] As described with reference to FIGS. 3 and FIG. 5 and the like, the plurality of lenses 411 may be composed of a front lens group having a negative refractive power or substantially no power and a rear lens group 411R having a positive refractive power, which are arranged in order from the side where the excitation light EL1 or the like is incident to the side where it exits (negative Z-axis direction). For the plurality of lenses 411, when the focal length of the plurality of lenses 411 is ft, the focal length of the front lens group 411F is f1, and the focal length of the rear lens group 411R is f2, (8) -0.24 < ft / f1 < 0.08 and (9) 0.35 < ft / f2 < 0.7 may be satisfied. Thereby, for example, compared with the case of having a telephoto configuration, the focal length of the objective lens can be shortened.

[0156] As described with reference to FIG. 3 and the like, the particle analyzer 100 may include an aperture stop 414 provided between the front lens group 411F and the rear lens group 411R. Thereby, the amount of light passing between the front lens group 411F and the rear lens group 411R can be adjusted.

[0157] 4 and other drawings, the lens structure 41 may condense the light (fluorescence FL and scattered light BSC) emitted from the particle 51 toward the detection unit 7. This allows the light to be detected to be efficiently guided to the detection unit 7.

[0158] As described with reference to Figure 15 etc., the outer dimensions of the multiple lenses 451 may be substantially smaller from the side where the excitation light EL1 etc. is incident to the side where it is emitted (positive direction of the Z axis). By providing such a telephoto configuration, it is more likely that the number of lenses can be reduced and costs can be reduced compared to, for example, a retrofocus configuration (reverse telephoto configuration). Furthermore, for example, multiple lenses can be fitted and held in a single lens frame, which can reduce the costs of mechanical parts accordingly.

[0159] As described with reference to FIG. 1 etc., the particle analysis device 100 may include an optical system (mirror 3) disposed between the light source 1, the lens structure 41 (objective lens 4), and the detection unit 7. The optical system (mirror 3) may include a central portion 31 that reflects the excitation light EL1 etc., and a peripheral portion 32 that transmits the light (fluorescence light FL and scattered light BSC) emitted from the particles 51. For example, using an optical system (mirror 3) configured in this manner, the excitation light EL1 etc. from the light source 1 can be guided to the lens structure 41, and the fluorescence FL etc. from the objective lens 4 can be guided to the detection unit 7.

[0160] The particle analysis method described with reference to Figures 1, 3, 20, etc. is also an aspect of the present disclosure. The particle analysis method includes using a lens structure 41 (objective lens 4) to focus excitation light EL1, etc., including light with a wavelength of 400 nm or less, at a predetermined position (spot 51s) in a flow path 53 (step S1), detecting light (fluorescence FL and scattered light BSC) emitted from particles 51 flowing through the predetermined position when the particles 51 are excited by the excitation light EL1, etc. (step S2), and processing the detected data (step S3). The lens structure 41 includes a plurality of lenses 411 arranged along the optical axis of the excitation light EL1, etc. (along the negative Z-axis direction), and a lens frame 412 that holds the plurality of lenses 411. The position of at least one of the plurality of lenses 411 (lens G12, lens G13, lens G15, and lens G16) within the lens frame 412 is determined by abutting against an adjacent lens. As explained above, this particle analysis method also makes it possible to suppress deterioration of optical characteristics.

[0161] The optical measurement device 110 described with reference to Figures 1, 3, etc. is also one aspect of the present disclosure. The optical measurement device 110 includes a light source 1 that emits excitation light EL1 and the like including light with a wavelength of 400 nm or less, a lens structure 41 (objective lens 4) that focuses the excitation light EL1 and the like at a predetermined position (spot 51s) in a flow path 53, and a detection unit 7 that detects light (fluorescence FL and scattered light BSC) emitted from particles 51 when the particles 51 flowing through the predetermined position are excited by the excitation light EL1 and the like. The lens structure 41 includes a plurality of lenses 411 arranged along the optical axis of the excitation light EL1 and the like (along the negative direction of the Z axis), and a lens frame 412 that holds the plurality of lenses 411. The position of at least one of the plurality of lenses 411 (lens G12, lens G13, lens G15, and lens G16) within the lens frame 412 is determined by abutting against the lens adjacent to that lens. As explained above, such an optical measurement device 110 also makes it possible to suppress deterioration of optical characteristics.

[0162] The effects described in this disclosure are merely examples and are not limited to the disclosed contents. Other effects may also be obtained.

[0163] Although the embodiments of the present disclosure have been described above, the technical scope of the present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the gist of the present disclosure. Furthermore, components of different embodiments and modifications may be combined as appropriate.

[0164] The disclosed technology may have the following configuration. [1] a light source that emits excitation light containing light with a wavelength of 400 nm or less; a lens structure that focuses the excitation light at a predetermined position within the flow channel; a detection unit that detects light emitted from particles flowing through the predetermined position when the particles are excited by the excitation light; a processing unit that processes detection data acquired by the detection unit; Equipped with The lens structure comprises: a plurality of lenses arranged along the optical axis of the excitation light; a lens frame for holding the plurality of lenses; Equipped with At least one of the plurality of lenses is positioned within the lens frame by abutting against a lens adjacent to the lens. Particle analyzer. [2] The plurality of lenses include a positive lens closest to the test object, and the glass material of the positive lens has a refractive index at the d-line of nd and an Abbe number at the d-line of νd, where nd is the refractive index at the d-line and νd is the Abbe number at the d-line, respectively. (1) 1.73 <nd<1.83 and (2)45<νd Satisfy the [1] The particle analyzer according to [1]. [3] The plurality of lenses include at least three or more positive lenses, and the glass material of the three or more positive lenses has a refractive index at the d-line of nd, an Abbe number at the d-line of νd, and a partial dispersion ratio between the g-line and the F-line of PgF, such that: (3)nd<1.52, (4)79<νd and (5) PgF<0.54 Satisfy the The particle analyzer according to [1] or [2]. [4] The plurality of lenses include at least two or more negative lenses, and the glass material of the two or more negative lenses has a refractive index at the d-line of nd and an Abbe number at the d-line of νd, where nd is a refractive index at the d-line and νd is an Abbe number at the d-line, respectively. (6)nd<1.78 and (7)29<νd Satisfy the The particle analyzer according to any one of [1] to [3]. [5] the plurality of lenses are arranged in order from the side where the excitation light is incident to the side where the excitation light is emitted, and are composed of a front lens group having negative refractive power or substantially no power, and a rear lens group having positive refractive power. The particle analyzer according to any one of [1] to [4]. [6] When the focal lengths of the plurality of lenses are ft, the focal length of the front lens group is f1, and the focal length of the rear lens group is f2, the following formula is obtained: (8)-0.24 <ft / f1<0.08 and (9) 0.35 <ft / f2<0.7 Satisfy the [5] The particle analysis device according to [5]. [7] an aperture stop provided between the front lens group and the rear lens group; [5] or [6]. The particle analyzer according to [5] or [6]. [8] The particle analysis device according to any one of [1] to [7], wherein the lens structure focuses the light emitted from the particles toward the detection unit. [9] The outer shapes of the lenses are substantially smaller from the side where the excitation light is incident to the side where the excitation light is emitted. The particle analyzer according to any one of [1] to [4].

[10] an optical system disposed between the light source, the lens structure, and the detection unit; The particle analyzer according to any one of [1] to [9].

[11] The optical system comprises: a central portion that reflects the excitation light; a peripheral portion that transmits the light emitted from the particle; Including,

[10] The particle analysis device according to

[10] .

[12] The light source emits excitation light containing light with a wavelength of 350 nm or less. The particle analyzer according to any one of [1] to

[11] .

[13] The light source also emits excitation light containing light with a wavelength longer than 400 nm. The particle analyzer according to any one of [1] to

[12] .

[14] using a lens structure to focus excitation light containing light with a wavelength of 400 nm or less at a predetermined position within the flow channel; detecting light emitted from particles flowing through the predetermined position when the particles are excited by the excitation light; processing the detection data; Including, The lens structure comprises: a plurality of lenses arranged along the optical axis of the excitation light; a lens frame for holding the plurality of lenses; Equipped with At least one of the plurality of lenses is positioned within the lens frame by abutting against a lens adjacent to the lens. Particle analysis methods.

[15] a light source that emits excitation light containing light with a wavelength of 400 nm or less; a lens structure that focuses the excitation light at a predetermined position within the flow channel; a detection unit that detects light emitted from particles flowing through the predetermined position when the particles are excited by the excitation light; Equipped with The lens structure comprises: a plurality of lenses arranged along the optical axis of the excitation light; a lens frame for holding the plurality of lenses; Equipped with At least one of the plurality of lenses is positioned within the lens frame by abutting against a lens adjacent to the lens. Optical measurement equipment. [Explanation of symbols]

[0165] 100 particle analyzer 110 Optical measurement equipment 120 Processing control section 1 light source 11 Light source 12 light source 13 Light source 14 Light source 15 light source 2 Mirror Group 21. Mirror 22 Mirror 23. Mirror 24. Mirror 25. Mirror 3. Mirror 31 Center 32 Periphery 4 Objective Lenses 5. Microchip 51 particles 51s Spot 52 Biological samples 53 Flow path 6 Imaging lenses 7. Detection unit 8. Detection unit 41 Lens structure 411 Multiple Lenses 411F front lens group 411R rear lens group G11 lens G12 lens G13 lens G14 lens G15 lens G16 lens G17 Lens G18 Lens 412 Lens frame 412F front frame 412Fa opening 412Fb opening 412Fc protrusion 412Fd Protrusion 412R rear frame 412Ra opening 412Rb opening 412Rc protrusion 412Rd Protrusion 413 Fixing member N11 screw N13 screw N14 screw RG1415 Ring RG1617 Ring AD18 Adhesive 414 Aperture Diaphragm

Claims

1. a light source that emits excitation light containing light with a wavelength of 400 nm or less; a lens structure that focuses the excitation light at a predetermined position within the flow channel; a detection unit that detects light emitted from particles flowing through the predetermined position when the particles are excited by the excitation light; a processing unit that processes detection data acquired by the detection unit; Equipped with The lens structure comprises: a plurality of lenses arranged along the optical axis of the excitation light; a lens frame for holding the plurality of lenses; Equipped with At least one of the plurality of lenses is positioned within the lens frame by being brought into contact with a lens adjacent to the lens. Particle analyzer.

2. The plurality of lenses include a positive lens closest to the test object, and the glass material of the positive lens has a refractive index at the d-line of nd and an Abbe number at the d-line of νd, as follows: (1) 1.73<nd<1.83 and (2) 45<νd Satisfy the The particle analyzer of claim 1 .

3. The plurality of lenses include at least three or more positive lenses, and the glass material of the three or more positive lenses has a refractive index at the d-line of nd, an Abbe number at the d-line of νd, and a partial dispersion ratio between the g-line and the F-line of PgF, where nd is a refractive index at the d-line, νd is an Abbe number at the d-line, and PgF is a partial dispersion ratio between the g-line and the F-line. (3) nd<1.52, (4) 79<νd and (5) PgF<0.54 Satisfy the The particle analyzer of claim 1 .

4. The plurality of lenses include at least two or more negative lenses, and the glass material of the two or more negative lenses has a refractive index at the d-line of nd and an Abbe number at the d-line of νd, where nd is a refractive index at the d-line and νd is an Abbe number at the d-line, respectively. (6)nd<1.78 and (7) 29<νd Satisfy the The particle analyzer of claim 1 .

5. the plurality of lenses are arranged in order from the side where the excitation light is incident to the side where the excitation light is emitted, and are composed of a front lens group having negative refractive power or substantially no power, and a rear lens group having positive refractive power. The particle analyzer of claim 1 .

6. When the focal length of the plurality of lenses is ft, the focal length of the front lens group is f1, and the focal length of the rear lens group is f2, the following formula is given: (8) -0.24<ft / f1<0.08 and (9) 0.35<ft / f2<0.7 Satisfy the The particle analyzer of claim 5 .

7. an aperture stop provided between the front lens group and the rear lens group; The particle analyzer of claim 5 .

8. The particle analysis device according to claim 1 , wherein the lens structure focuses the light emitted from the particles toward the detection unit.

9. The outer shapes of the lenses are substantially smaller from the side where the excitation light is incident to the side where the excitation light is emitted. The particle analyzer of claim 1 .

10. an optical system disposed between the light source, the lens structure, and the detection unit; The particle analyzer of claim 1 .

11. The optical system comprises: a central portion that reflects the excitation light; a peripheral portion that transmits the light emitted from the particle; Including, The particle analysis device of claim 10.

12. The light source emits excitation light containing light with a wavelength of 350 nm or less. The particle analyzer of claim 1 .

13. The light source also emits excitation light containing light with a wavelength longer than 400 nm. The particle analyzer of claim 1 .

14. using a lens structure to focus excitation light containing light with a wavelength of 400 nm or less at a predetermined position within the flow channel; detecting light emitted from particles flowing through the predetermined position when the particles are excited by the excitation light; processing the detection data; Including, The lens structure comprises: a plurality of lenses arranged along the optical axis of the excitation light; a lens frame for holding the plurality of lenses; Equipped with At least one of the plurality of lenses is positioned within the lens frame by being brought into contact with a lens adjacent to the lens. Particle analysis methods.

15. a light source that emits excitation light containing light with a wavelength of 400 nm or less; a lens structure that focuses the excitation light at a predetermined position within the flow channel; a detection unit that detects light emitted from particles flowing through the predetermined position when the particles are excited by the excitation light; Equipped with The lens structure comprises: a plurality of lenses arranged along the optical axis of the excitation light; a lens frame for holding the plurality of lenses; Equipped with At least one of the plurality of lenses is positioned within the lens frame by being brought into contact with a lens adjacent to the lens. Optical measurement equipment.

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