Confocal microscope objective lens with high optical flux and long working distance

Abstract

The invention provides a confocal microscope objective lens with high optical flux and long working distance, the confocal microscope objective lens comprises a first lens group and a second lens group which are sequentially arranged along the light transmission direction, the first lens group comprises a first lens, a second lens, a third lens and a fourth lens which are sequentially arranged along the light transmission direction, the first lens is a negative lens, and the second lens is a positive lens. The working distance is prolonged; the combination of the second lens, the third lens and the fourth lens has positive focal power and is used for focusing light, so that the objective lens obtains a larger numerical aperture; the second lens group comprises a sixth lens and a seventh lens which are sequentially arranged in the light transmission direction, and the combination of the sixth lens and the seventh lens has negative focal power and is used for enlarging the aperture of the light beam and reducing the angle of the incident light beam at the same time. According to the scheme, a view field of 12 mm is achieved, the numerical aperture reaches 0.5, the working distance reaches 17.7 mm, and excellent imaging performance is achieved while the large view field, the high resolution and the long working distance are considered.

Description

Technical Field

[0001] The present invention relates to the technical field of microscopes, in particular to a confocal microscope objective lens with high optical flux and long working distance. Background Art

[0002] Laser scanning confocal microscopy (LSCM) is one of the most versatile fluorescence microscopy tools used in biological research, boasting high resolution, high sensitivity, and high magnification. The key technology of LSCM lies in imaging a single point in space (i.e., the focal point) at a time, then using computer-controlled point-by-point scanning to form a two-dimensional or three-dimensional image of the sample. During this process, light signals originating outside the focal plane do not interfere with the imaging, significantly improving the clarity and detail resolution of the microscope image. LSCM is commonly used in areas such as tissue optical sectioning, three-dimensional image reconstruction, and semiconductor and micro-nanofabrication inspection.

[0003] Laser confocal microscopy uses a point scanning imaging method. This characteristic determines that its image is generated by scanning point by point, so the imaging speed is relatively slow. High-throughput objectives with high numerical aperture (NA) and large field of view can collect more sample information, effectively reducing the number of mechanical movements of the objective or sample, thereby significantly improving imaging efficiency. With the continuous expansion of in vivo imaging applications, the demand for larger fields of view, longer working distances, and high-speed and high-resolution imaging is increasing, and multi-channel large-field confocal microscopes have emerged. In an optical system, the larger the numerical aperture, the higher the resolution of the objective, but it is usually accompanied by a shorter working distance. This is because a larger incident angle can collect more light. However, increasing the NA tends to narrow the field of view because high-NA objectives require more complex optical corrections, which limits the image size.

[0004] In 2016, McConnell et al. established an optical lens system in the article "A novel optical microscope for imaging large embryos and tissue volumes with sub-cellular resolution throughout" to perform 3D imaging of objects up to 6 mm wide and 3 mm thick.

[0005] In 2017, Shaun Pacheco et al. proposed the development of a new confocal fluorescence microscope with high resolution, high speed, long working distance, and large field of view in their article "High resolution, high speed, long working distance, large field of view confocal fluorescence microscope." Its numerical aperture (NA) reached 0.5, with a 3mm × 3mm field of view and a 12mm working distance.

[0006] In 2019, Jingtao Fan et al. proposed a real-time, ultra-large-scale, high-resolution (RUSH) imaging platform in the article Video-rate imaging of biological dynamics at centimetre scale and micrometer resolution. The objective lens has a 10×12mm 2 The field of view is 0.35, and the imaging is done in the visible light band.

[0007] It can be seen that in optical microscope systems, the field of view, resolution and working distance restrict each other. Therefore, achieving high-throughput imaging with both high resolution and large field of view is still one of the key issues in current research. Summary of the Invention

[0008] Based on the above-mentioned problems existing in the prior art, the present invention aims to solve the technical problem that in the optical microscope system in the prior art, the field of view, resolution and working distance are mutually restricted, and therefore it is difficult to achieve high-throughput imaging with both high resolution and large field of view.

[0009] The present invention provides a confocal microscope objective lens with high optical flux and long working distance, which comprises a first lens group with positive optical power and a second lens group with negative optical power arranged in sequence along the light transmission direction, wherein:

[0010] The first lens group includes a first lens, a second lens, a third lens, and a fourth lens arranged in sequence along the light transmission direction, wherein the first lens is a negative lens, used to extend the working distance of the objective lens and correct partial spherical aberration and field curvature; the combination of the second lens, the third lens, and the fourth lens has positive refractive power, used to focus light, so that the objective lens obtains a larger numerical aperture;

[0011] The second lens group includes a sixth lens and a seventh lens arranged in sequence along the light transmission direction. The combination of the sixth lens and the seventh lens has a negative optical focal length, which is used to expand the beam aperture while reducing the incident beam angle, thereby reducing the generation of objective lens aberrations.

[0012] According to an embodiment of the present invention, the focal power φ1 of the first lens group is in the range of 0.018<φ1<0.03, and the focal power φ2 of the second lens group is in the range of -0.009<φ2<-0.008.

[0013] According to an embodiment of the present invention, the optical power of the first lens ranges from -0.01 to -0.02; the optical power of the combination of the second lens, the third lens and the fourth lens ranges from 0.02 to 0.03.

[0014] According to an embodiment of the present invention, the optical power of the combination of the sixth lens and the seventh lens ranges from -0.03 to -0.02.

[0015] According to an embodiment of the present invention, the first lens group further includes a fifth lens disposed on a side of the fourth lens away from the first lens, and the fifth lens is used to correct field curvature and collect light beams so that the objective lens obtains a larger numerical aperture.

[0016] According to an embodiment of the present invention, the second lens group further includes an eighth lens disposed on a side of the seventh lens away from the sixth lens. The eighth lens has positive optical power and is used to reduce the aperture of the incident light beam, thereby facilitating the correction of aberrations.

[0017] According to an embodiment of the present invention, the optical power of the eighth lens is in the range of 0.007 to 0.008.

[0018] According to one embodiment of the present invention, the high optical flux and long working distance confocal microscope objective further includes a third lens group with positive optical power arranged between the first lens group and the second lens group, and the third lens group is used to correct spherical aberration, field curvature and axial chromatic aberration.

[0019] According to one embodiment of the present invention, the third lens group includes a tenth lens, an eleventh lens, a twelfth lens, a thirteenth lens, a fourteenth lens, and a fifteenth lens, which are sequentially arranged along the light transmission direction, wherein the combination of the tenth lens and the eleventh lens has positive optical power for correcting a portion of axial chromatic aberration and spherical aberration; the combination of the twelfth lens and the thirteenth lens has negative optical power for correcting a portion of axial chromatic aberration and spherical aberration; and the combination of the fourteenth lens and the fifteenth lens has negative optical power for correcting a portion of axial chromatic aberration and spherical aberration.

[0020] According to an embodiment of the present invention, the optical power φ3 of the third lens group is in the range of 0.008<φ3<0.012.

[0021] The beneficial effects of the present invention are:

[0022] The present invention provides a high-optical-throughput, long-working-distance confocal microscope objective lens with a 12mm field of view, a numerical aperture of 0.5, a working distance of 17.7mm, and an imaging band covering 420nm to 680nm, which covers the visible light band and is suitable for most usage scenarios. It reaches the diffraction limit within the entire field of view, ensuring high-quality imaging effects. It achieves excellent imaging performance while taking into account a large field of view, high resolution, and a long working distance. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 1 is a schematic structural diagram of a confocal microscope objective lens with high optical flux and long working distance provided by an embodiment of the present invention;

[0025] Figure 2 1 is a schematic diagram of a modulation transfer function curve of a high optical flux and long working distance confocal microscope objective lens provided by an embodiment of the present invention;

[0026] Figure 3 This is a point diagram of a confocal microscope objective lens with high optical flux and long working distance provided by an embodiment of the present invention;

[0027] Figure 4 Schematic diagram of an axial chromatic aberration curve of a high optical flux and long working distance confocal microscope objective provided by an embodiment of the present invention;

[0028] Reference numerals: G1, first lens group; G11, first lens; G12, second lens; G13, third lens; G14, fourth lens; G15, fifth lens; G2, second lens group; G21, sixth lens; G22, seventh lens; G23, eighth lens; G24, ninth lens; G3, third lens group; G31, tenth lens; G32, eleventh lens; G33, twelfth lens; G34, thirteenth lens; G35, fourteenth lens; G36, fifteenth lens; G37, sixteenth lens; G38, seventeenth lens. DETAILED DESCRIPTION

[0029] The following descriptions of the embodiments refer to the accompanying drawings to illustrate specific embodiments in which the present invention may be implemented.

[0030] The present invention provides a confocal microscope objective lens with high optical flux and long working distance, the structure of which is as follows: Figure 1 As shown, including along the light transmission direction ( Figure 1 A first lens group G1 with positive focal power, a third lens group G3 with positive focal power, and a second lens group G2 with negative focal power are arranged in sequence (from right to left in the figure), wherein the first lens group G1 is arranged on the side close to the object side, and the second lens group G2 is arranged on the side close to the image side; the optical power φ1 of the first lens group G1 is in the range of 0.018<φ1<0.03, and is used to collect light beams, form a high numerical aperture, and correct spherical aberration, coma, and axial chromatic aberration; the optical power φ2 of the second lens group G2 is in the range of -0.009<φ2<-0.008, and is used to correct spherical aberration, coma, and field curvature; the optical power φ3 of the third lens group G3 is in the range of 0.008<φ3<0.012, and is used to correct spherical aberration, field curvature, and axial chromatic aberration.

[0031] In this solution, the design parameters of the objective lens are: field of view of 12 mm, numerical aperture of 0.5, and working distance of 17.7 mm.

[0032] Exemplary first lens group G1

[0033] The first lens group G1 includes a first lens G11, a second lens G12, a third lens G13, a fourth lens G14 and a fifth lens G15, which are arranged in sequence along the light transmission direction, wherein the first lens G11 is a negative lens, used to extend the working distance of the objective lens and correct some spherical aberration and field curvature; the combination of the second lens G12, the third lens G13 and the fourth lens G14 has positive optical power, used to focus light, so that the objective lens obtains a larger numerical aperture; the fifth lens G15 is used to correct field curvature and collect light beams, so that the objective lens obtains a larger numerical aperture.

[0034] Specifically, the focal power of the first lens G11 ranges from -0.01 to -0.02; the focal power of the combination of the second lens G12, the third lens G13, and the fourth lens G14 ranges from 0.02 to 0.03.

[0035] More specifically, the focal lengths of the first lens G11, the second lens G12, the third lens G13, the fourth lens G14 and the fifth lens G15 are respectively: -75 <f11<-70、80<f12<90、330<f13<340、70<f14<80、-5200<f15<-5100。

[0036] Furthermore, the refractive indexes of the first lens G11, the second lens G12, the third lens G13, the fourth lens G14 and the fifth lens G15 are respectively: 1.66 <nd11<1.7、1.9<nd12<1.93、1.9<nd13<1.93、1.55<nd14<1.6、1.4<nd15<1.45。

[0037] Exemplary second lens group G2

[0038] The second lens group G2 includes a ninth lens element G24, a sixth lens element G21, a seventh lens element G22, and an eighth lens element G23, arranged in sequence along the light transmission direction. The combination of the sixth lens element G21 and the seventh lens element G22 has negative refractive power, which is used to expand the optical beam aperture while reducing the incident beam angle, thereby reducing the generation of objective aberrations. The eighth lens element G23 has positive refractive power, which is used to reduce the incident beam aperture, thereby facilitating aberration correction. The ninth lens element G24 is used to correct partial spherical aberration and field curvature.

[0039] Specifically, the focal power of the combination of the sixth lens G21 and the seventh lens G22 ranges from -0.03 to -0.02; and the focal power of the eighth lens G23 ranges from 0.007 to 0.008.

[0040] More specifically, the focal lengths of the ninth lens G24, the sixth lens G21, the seventh lens G22, and the eighth lens G23 are respectively: -288 <f24<-280、-260<f21<-255、-53<f22<-49、139<f23<143;

[0041] Furthermore, the refractive indices of the ninth lens G24, the sixth lens G21, the seventh lens G22, and the eighth lens G23 are respectively: 1.8 <nd24<1.86、1.6<nd21<1.65、1.7<nd22<1.75、1.8<nd23<1.9。

[0042] Exemplary third lens group G3

[0043] The third lens group G3 includes a tenth lens G31, an eleventh lens G32, a twelfth lens G33, a thirteenth lens G34, a sixteenth lens G37, a fourteenth lens G35, a fifteenth lens G36, and a seventeenth lens G38, arranged in sequence along the light transmission direction. The combination of the tenth lens G31 and the eleventh lens G32 has positive refractive power for partially correcting axial chromatic aberration and spherical aberration; the combination of the twelfth lens G33 and the thirteenth lens G34 has negative refractive power for partially correcting axial chromatic aberration and spherical aberration; the combination of the fourteenth lens G35 and the fifteenth lens G36 has negative refractive power for partially correcting axial chromatic aberration and spherical aberration. The sixteenth lens G37 and the seventeenth lens G38 are both used to correct partial spherical aberration.

[0044] Specifically, the focal power of the combination of the fourteenth lens G35 and the fifteenth lens G36 ranges from -0.004 to -0.003; the focal power of the combination of the twelfth lens G33 and the thirteenth lens G34 ranges from -0.007 to -0.006; and the focal power of the combination of the tenth lens G31 and the eleventh lens G32 ranges from 0.004 to 0.005.

[0045] More specifically, the focal lengths of the tenth lens G31, the eleventh lens G32, the twelfth lens G33, the thirteenth lens G34, the sixteenth lens G37, the fourteenth lens G35, the fifteenth lens G36, and the seventeenth lens G38 are respectively: 130 <f31<140、-345<f32<-340、-60<f33<-50、90<f34<100、90<f37<100、-73<f35<-65、90<f36<100、185<f38<190。

[0046] Furthermore, the refractive indexes of the tenth lens G31, the eleventh lens G32, the twelfth lens G33, the thirteenth lens G34, the sixteenth lens G37, the fourteenth lens G35, the fifteenth lens G36 and the seventeenth lens G38 are respectively: 1.4 <nd31<1.45、1.6<nd32<1.65、1.6<nd33<1.65、1.55<nd34<1.6、1.55<nd37<1.6、1.94<nd35<2、1.55<nd36<1.6、1.55<nd38<1.6。

[0047] exist Figure 1 In the figure, all lens surfaces (a total of 35 surfaces) are numbered from left to right. The range of curvature radius of the surface represented by each number is:

[0048] 95 < c1 < 100, 485 < c2 < 495, -215 < c3 < -205, 45 < c4 < 50, 80 < c5 < 90, 50 < c6 < 60, -40 < c7 < -50, -60 < c8 < -50, 1380 < c9 < 1390, -120 < c10 < -110, 290 < c12 < 300, -70 < C13 < -60, -60 < c14 < -50, -470 < c15 < -460, 190 < c16 < 200, -80 < c17 < -70, 140 < c18 < 150, -90 < c19 < -80, -90 < c20 < -80, 60 < c21 < 70, 110 < c22 < 120, 60 < c23 < 70, 70 < c24 < 80, -280 < c25 < -290, 40 < c26 < 50, 40 < c27 < 50, 50 < c28 < 60, -230 < c29 < -220, 110 < c30 < 120, 180 < c31 < 190, 30 < c32 < 40, 60 < c33 < 70, 40 < c34 < 50, 20 < c35 < 30。

[0049] From left to right, the air gaps between adjacent two lenses are successively as follows:

[0050] 40 < d1 < 50, 1 < d2 < 5, 8 < d3 < 13, 0.3 < d4 < 1, 1 < d5 < 2, 1 < d6 < 2, 1 < d7 < 2, 1 < d8 < 2, 0.5 < d9 < 2, 4 < d10 < 5, 0.5 < d11 < 1.5, 1 < d12 < 2, 4 < d13 < 5, 0.5 < d14 < 1.5, 0.5 < d15 < 1.5, 0.5 < d16 < 1.5, 15 < d17 < 20, where d17 refers to the distance from the rightmost lens to the object surface.

[0051] Table 1 gives the relevant parameters of all lens surfaces in a specific embodiment of the present invention:

[0052] Table 1 Relevant Parameters of Lens Surfaces

[0053]

[0054]

[0055] In Table 1, the surface represented by serial number 11 is the aperture surface. The aperture surface refers to a specific position on the focal plane of the objective lens, and usually an aperture is installed. The aperture is an optical element used to control the amount and angle of the light beam entering the objective lens, thereby affecting the quality and characteristics of imaging.

[0056] Figure 2Schematic diagram of the modulation transfer function (MTF) curve of the objective lens, the horizontal axis represents the spatial frequency, the unit is "line pair / millimeter" (LP / MM), the vertical axis represents the MTF value, ranging from 0 to 1, the larger the value, the clearer the image. Figure 2 In the figure, the half field of view of the objective lens is 6mm. For example, to ensure the imaging quality of the full field of view, five fields of view are selected at equal intervals, namely 0mm, 1.48mm, 2.96mm, 4.43mm, and 6mm. It can be seen that the MTF curve of each field of view is close to the diffraction limit curve, indicating that the imaging quality of the system is close to the diffraction limit.

[0057] Figure 3 This is the point diagram of the objective lens, which shows the concentration of the light spot on the imaging plane and reflects the resolution capability of the lens. Figure 3 In the middle, the half-image height at the image plane is 6mm, so the full field of view of this solution can reach 12mm; Figure 3 The visible light spot basically falls within the Airy disk, further verifying the high-resolution imaging capability of the objective lens.

[0058] Figure 4 This is a schematic diagram of the axial chromatic aberration curve. The ordinate represents the normalized pupil coordinate, and the abscissa represents the deviation of the imaging position. The closer the curve is to the center, the smaller the deviation. Figure 4 In the figure, it can be seen that the imaging band of this scheme covers 420nm~680nm; Figure 4 Visible axial chromatic aberration has been effectively corrected to ensure color consistency and accuracy of imaging.

[0059] In summary, the present invention provides a high optical flux and long working distance confocal microscope objective lens with a field of view of 12 mm, a numerical aperture of 0.5, a working distance of up to 17.7 mm, and an imaging band covering 420 nm to 680 nm. This band covers the visible light band and is suitable for most usage scenarios. It reaches the diffraction limit within the entire field of view, ensuring high-quality imaging effects. It achieves excellent imaging performance while taking into account a large field of view, high resolution and long working distance.

[0060] It should be noted that although the present invention is disclosed above with specific embodiments, the above embodiments are not intended to limit the present invention. Ordinary technicians in this field can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope defined by the claims.

Claims

1. A confocal microscope objective lens with high optical throughput and long working distance, characterized in that: The invention comprises a first lens group (G1) with positive optical power and a second lens group (G2) with negative optical power, which are sequentially arranged along the light transmission direction, wherein: The first lens group (G1) includes a first lens (G11), a second lens (G12), a third lens (G13), and a fourth lens (G14) arranged in sequence along the light transmission direction, wherein the first lens (G11) is a negative lens, used to extend the working distance of the objective lens and correct partial spherical aberration and field curvature; the combination of the second lens (G12), the third lens (G13), and the fourth lens (G14) has positive optical power, used to focus light, so that the objective lens obtains a larger numerical aperture; The second lens group (G2) includes a sixth lens (G21) and a seventh lens (G22) arranged in sequence along the light transmission direction. The combination of the sixth lens (G21) and the seventh lens (G22) has a negative optical focal length, which is used to expand the beam aperture while reducing the incident beam angle, thereby reducing the generation of objective lens aberrations.

2. The high optical flux and long working distance confocal microscope objective lens according to claim 1, characterized in that: The optical power φ1 of the first lens group (G1) has a value range of 0.018<φ1<0.03, and the optical power φ2 of the second lens group (G2) has a value range of -0.009<φ2<-0.

008.

3. The high optical flux and long working distance confocal microscope objective lens according to claim 1, characterized in that: The optical focal length of the first lens (G11) ranges from -0.01 to -0.02; the optical focal length of the combination of the second lens (G12), the third lens (G13) and the fourth lens (G14) ranges from 0.02 to 0.

03.

4. The high optical flux and long working distance confocal microscope objective lens according to claim 1, characterized in that: The optical focal length of the combination of the sixth lens (G21) and the seventh lens (G22) ranges from -0.03 to -0.

02.

5. The high optical flux and long working distance confocal microscope objective lens according to claim 1, characterized in that: The first lens group (G1) further includes a fifth lens (G15) disposed on a side of the fourth lens (G14) away from the first lens (G11); the fifth lens (G15) is used to correct field curvature and collect light beams so that the objective lens obtains a larger numerical aperture.

6. The high optical flux and long working distance confocal microscope objective lens according to claim 1, characterized in that: The second lens group (G2) includes an eighth lens (G23) arranged on the side of the seventh lens (G22) away from the sixth lens (G21). The eighth lens (G23) has positive optical power and is used to reduce the aperture of the incident light beam, thereby facilitating the correction of aberrations.

7. The high optical flux and long working distance confocal microscope objective lens according to claim 6, characterized in that: The optical power of the eighth lens (G23) ranges from 0.007 to 0.

008.

8. The high optical flux and long working distance confocal microscope objective lens according to claim 1, characterized in that: The invention also includes a third lens group (G3) with positive optical power arranged between the first lens group (G1) and the second lens group (G2), and the third lens group (G3) is used to correct spherical aberration, field curvature and axial chromatic aberration.

9. The high optical flux and long working distance confocal microscope objective lens according to claim 8, characterized in that: The third lens group (G3) includes a tenth lens (G31), an eleventh lens (G32), a twelfth lens (G33), a thirteenth lens (G34), a fourteenth lens (G35) and a fifteenth lens (G36) arranged in sequence along the light transmission direction, wherein the combination of the tenth lens (G31) and the eleventh lens (G32) has positive focal power for correcting part of axial chromatic aberration and spherical aberration; the combination of the twelfth lens (G33) and the thirteenth lens (G34) has negative focal power for correcting part of axial chromatic aberration and spherical aberration; and the combination of the fourteenth lens (G35) and the fifteenth lens (G36) has negative focal power for correcting part of axial chromatic aberration and spherical aberration.

10. The high optical flux and long working distance confocal microscope objective lens according to claim 8, characterized in that: The focal power φ3 of the third lens group (G3) has a value range of 0.008<φ3<0.012.

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