All-glass spherical wide-spectrum imaging lens
By using a five-lens spherical lens design made entirely of glass and employing a double-cemented structure, the aberration problem of existing lenses in a wide spectral range is solved, achieving high-definition imaging in the 340nm-1550nm band, with a compact lens structure.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZHEJIANG UNIV
- Filing Date
- 2022-09-09
- Publication Date
- 2026-05-19
AI Technical Summary
Existing lenses cannot perform effective optical imaging in the 340nm-1550nm band, especially in the near-ultraviolet and near-infrared bands where aberrations cannot be corrected, and the large number of lenses results in a non-compact structure.
The spherical lens, composed of five lenses made entirely of glass, uses a double-cemented structure design, including a combination of positive and negative lenses, to reduce system chromatic aberration and other aberrations, enabling wide-spectrum imaging.
It achieves high-definition imaging in the 340nm-1550nm band, with axial aberration less than 100μm, meets the requirements of wide-band confocal imaging, and has a compact lens structure.
Smart Images
Figure CN116299957B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of lens imaging, and particularly to an ultra-vision lens system with a full-glass spherical surface, namely, a 9-megapixel blacklight full-color lens CN112099194B. Background Art
[0002] In recent years, the global demand for lenses has been growing steadily. People's demand for lenses is also constantly increasing, putting forward new requirements for the functions of lenses. Lenses with multiple characteristics are usually more competitive in the market. In addition, optical lenses with low distortion, low aberration, and miniaturization are more favored in the lens market. Currently, optical lenses for imaging beyond visible light are emerging in the market. However, their deficiencies are relatively obvious, and several examples are listed below:
[0003] 1. After searching the existing patent literature, it is found that the Chinese patent application number is 202011062240.6, the patent name is 9-megapixel blacklight full-color lens, and the application date is September 30, 2020. This patent states that "a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, an aperture stop, a seventh lens, an eighth lens, a ninth lens, a tenth lens, an eleventh lens and an equivalent prism are arranged in sequence from front to back along the light incident direction. Focal length: 30mm, spectral range: 400nm - 1100nm, and the total optical length TTL satisfies 100mm < TTL < 125mm. The deficiencies of this patent are as follows: it can only image in the visible light range of 400nm - 1100nm and a very narrow short-wave infrared band, and cannot correct various aberrations and perform optical imaging in the near-ultraviolet and longer near-infrared bands. In addition, this lens uses a relatively large number of lenses. Summary of the Invention
[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a lens that can achieve clear imaging in a single-pixel area array image sensor with a size less than 5μm × 5μm within the wavelength range of 340nm - 1550nm. The lens material is made of full glass to meet the requirement of wide-band imaging of the lens. Through the double-glued structure, a compact optical lens is obtained, achieving high-definition imaging.
[0005] The present invention is realized through the following technical solutions: The lens includes five lenses arranged in sequence from the object side to the image side, namely, a first lens L1 with a positive optical power, a second lens L2 with a negative optical power, a third lens L3 with a positive optical power, a fourth lens L4 with a positive optical power, and a fifth lens L5 with a negative optical power. The first lens L1 and the second lens L2 are glued together to form a lens group.
[0006] Each of the lenses includes an object-end optical surface and an image-end optical surface. Both the object-end optical surface and the image-end optical surface of the lens are spherical. The object-end optical surface and the image-end optical surface of the first lens L1 are S11 and S12, respectively; the object-end optical surface and the image-end optical surface of the second lens L2 are S21 and S22, respectively; the object-end optical surface and the image-end optical surface of the third lens L3 are S31 and S32, respectively; the object-end optical surface and the image-end optical surface of the fourth lens L4 are S41 and S42, respectively; and the object-end optical surface and the image-end optical surface of the fifth lens L5 are S51 and S52, respectively.
[0007] The image-end optical surface S12 of the first lens L1 and the object-end optical surface S21 of the second lens L2 are closely attached to form a cemented doublet lens.
[0008] The total length of the lens, i.e. the distance between the center of the object optical surface S11 of the first lens L1 and the image plane IMA, satisfies the following relationship: 50mm < TTHI < 65mm.
[0009] Preferably, all the lenses are made of glass.
[0010] Preferably, the material of the first lens L1 is the same as that of the third lens L3, and the material of the fourth lens L4 is the same as that of the fifth lens L5.
[0011] Preferably, the material of the first lens L1 is required to have a transmittance that meets the following conditions: the transmittance of electromagnetic waves with a wavelength in the range of 340nm-1550nm within a thickness of 25mm is greater than 0.8.
[0012] Preferably, the material of the second lens L2 is required to have a transmittance that meets the following conditions: the transmittance of electromagnetic waves with wavelengths in the range of 340nm-1550nm within a thickness of 25mm is greater than 0.3.
[0013] Preferably, the material of the fourth lens L4 is required to have a transmittance that meets the following conditions: the transmittance of electromagnetic waves with wavelengths in the range of 340nm-1550nm within a thickness of 25mm is greater than 0.6.
[0014] Preferably, the refractive indices and Abbe numbers of the first lens L1, the second lens L2, and the fourth lens L4 satisfy the following relationship: n1 < 1.45, v1 > 90.0, n2 > 1.70, v2 < 55, v4 < 42. Wherein, n1 and n2 are the refractive indices of the first lens L1 and the second lens L2, respectively, and v1, v2, and v4 are the Abbe numbers of the first lens L1, the second lens L2, and the fourth lens L4, respectively.
[0015] Preferably, f1, f2, f3, f4, and f5 are set as the focal lengths of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, and the fifth lens L5, respectively; f12 is the focal length of the lens group formed by cementing the first lens L1 and the second lens L2 together; and f is the focal length of the entire lens. All parameters satisfy the relationship: 0.4 <f1 / f<0.6,-0.5<f2 / f<-0.3,0.7<f3 / f<0.9,0.8<f4 / f<1.0,-0.5<f5 / f<-0.3,-4.5<f12 / f<-2.5。
[0016] Preferably, R11, R21, R31, R41, and R51 are the radii of curvature of the object-end optical surfaces of the first lens L1, second lens L2, third lens L3, fourth lens L4, and fifth lens L5, respectively; R12, R22, R32, R42, and R52 are the radii of curvature of the image-end optical surfaces of the first lens L1, second lens L2, third lens L3, fourth lens L4, and fifth lens L5, respectively. Each radius of curvature satisfies the following relationship: 15mm. <R11<30mm,-25mm<R12<-10mm,R21=R12,50mm<R22<80mm,20mm<R31<40mm,R32=-R31,30mm<R41<50mm,-75mm<R42<-40mm,-18mm<R51<-8mm,50mm<R52<70mm。
[0017] Preferably, d1, d2, d3, and d4 are set as the thicknesses of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, and the fifth lens L5, respectively. The lenses satisfy the following relationship: 6mm. <d1<10mm,2mm<d2<3.5mm,6.5mm<d3<9.5mm,8.0mm<d4<9.5mm。
[0018] Compared with the prior art, the present invention has the following advantages: all surfaces are spherical to reduce processing costs and assembly difficulty; a cemented doublet achromatic lens is formed by combining a low-refractive-index, low-dispersion positive lens and a high-refractive-index, high-dispersion negative lens, thereby reducing chromatic aberration and other aberrations of the system; in the 340nm-1550nm band, the focal shift is 21μm and the axial aberration is 65μm, meeting the requirements of wide-spectrum confocal imaging, and optical imaging can be performed in the extremely wide band of 340nm-1550nm. Attached Figure Description
[0019] Figure 1 (a) is a structural diagram of the optical imaging lens system of Embodiment 1 of the present invention, including the object being photographed.
[0020] Figure 1 (b) is a structural diagram of the optical imaging lens system of Embodiment 1 of the present invention.
[0021] Figure 2 This is a dot matrix diagram of the optical imaging lens system of Embodiment 1 of the present invention.
[0022] Figure 3 This is the MTF curve of the polychromatic light of the optical imaging lens system of Embodiment 1 of the present invention.
[0023] Figure 4 This is the F-Tan (Theta) distortion curve of the optical imaging lens system of Embodiment 1 of the present invention.
[0024] Figure 5 This is the lens chromatic aberration curve of the optical imaging lens system in Embodiment 1 of the present invention.
[0025] Figure 6 This is the axial aberration curve of the optical imaging lens system in Embodiment 1 of the present invention.
[0026] Figure 7 This is the focal shift curve of the optical imaging lens system in Embodiment 1 of the present invention.
[0027] Figure 8 This is the field curvature curve of the optical imaging lens system in Embodiment 1 of the present invention. Detailed Implementation
[0028] The present invention will be further described below with reference to embodiments, structural diagrams and data curves.
[0029] like Figure 1 As shown, this invention provides a full-glass spherical broadband imaging lens structure. Figure 1 (a) in the diagram is a schematic diagram of the subject and lens structure imaging. Figure 1 (b) in the diagram is a schematic diagram of the lens structure.
[0030] Example 1
[0031] This embodiment provides an imaging lens with an object distance of 1500mm and an entrance pupil diameter of 12mm. The first lens L1 and the third lens L3 are both made of H-FK95N material, the second lens L2 is made of H-LAK53B material, and the fourth lens L4 and the fifth lens L5 are both made of QF50 material. The first lens L1 and the second lens L2 are cemented together to form a single lens with a cementing distance of 0.01mm. The third lens L3 has a biconvex symmetrical structure. The total length of the lens is 57.350mm. Specific parameters of each lens are detailed in Table 1. The lens corrects various aberrations in the 340nm-1550nm wavelength range, with axial aberration less than 100μm, thus solving the problem of internal confocality in a wide wavelength range.
[0032] Table 1
[0033]
[0034]
[0035] In Table 1, OBJ represents the object plane, IMA represents the image plane, and Stop corresponds to the aperture stop of the all-glass spherical broadband imaging lens, which is located at the S11 plane.
[0036] Example 2
[0037] This embodiment provides an imaging lens with an object distance of 1500mm and an entrance pupil diameter of 12mm. The first lens L1 and the third lens L3 are both made of H-FK95N material, the second lens L2 is made of H-LAK53B material, and the fourth lens L4 and the fifth lens L5 are both made of QF50GTI material. The first lens L1 and the second lens L2 are cemented together to form a single lens with a cementing distance of 0.01mm. The third lens L3 has a biconvex symmetrical structure. The total length of the lens is 57.350mm. Specific parameters of each lens are detailed in Table 2. The lens corrects various aberrations in the 340nm-1550nm wavelength range, with axial aberration less than 100μm, thus solving the problem of internal confocality over a wide wavelength range.
[0038] Table 2
[0039]
[0040] In Table 2, OBJ represents the object plane, IMA represents the image plane, and Stop corresponds to the aperture stop of the all-glass spherical broadband imaging lens, which is located at the S11 plane.
[0041] Example 3
[0042] This embodiment provides an imaging lens with an object distance of 1500mm and an entrance pupil diameter of 12mm. The first lens L1 and the third lens L3 are both made of D-FK95 material, the second lens L2 is made of N-LAK33A material, and the fourth lens L4 and the fifth lens L5 are both made of QF50 material. The first lens L1 and the second lens L2 are cemented together to form a single lens with a cementing distance of 0.01mm. The third lens L3 has a biconvex symmetrical structure. The total length of the lens is 57.351mm. Specific parameters of each lens are detailed in Table 3. The lens corrects various aberrations in the 340nm-1550nm wavelength range, with axial aberration less than 100μm, thus solving the problem of internal confocality in a wide wavelength range.
[0043] Table 3
[0044]
[0045] In Table 3, OBJ represents the object plane, IMA represents the image plane, and Stop corresponds to the aperture stop of the all-glass spherical broadband imaging lens, which is located at the S11 plane.
[0046] Since the parameters of Examples 1-3 are similar, the parameter curves of Example 1 will be used as a representative to illustrate the lens performance parameters, mainly including dot plots, polychromatic MTF curves, F-Tan (Theta) distortion curves, transverse chromatic aberration curves, axial aberration curves, focus shift curves, and field curvature curves, as detailed below:
[0047] Figure 2 The image-side dot plots are shown, with four different field-of-view locations: the image center (0.00 mm), the 0.5 field of view (2.50 mm), the 0.707 field of view (3.54 mm), and the edge field of view (5.00 mm). The root mean square radii (RMS Radius) of the diffuse spots at these four field-of-view locations are 2.545 μm, 2.882 μm, 2.789 μm, and 4.195 μm, respectively. Since the Airy disk radius of the lens is 4.61 μm, the lens design has reached the diffraction limit.
[0048] Figure 3 This is the MTF curve of the polychromatic light for this lens. To achieve clear imaging on an image sensor with a single pixel size of 5μm × 5μm, the lens's polychromatic light MTF curve must be greater than 0.2 at 100 lp / mm. This lens has a value of 0.4 at 100 lp / mm, which meets the imaging requirements.
[0049] Figure 4 This is the lens's F-Tan (Theta) distortion curve. Imaging lenses are required to have an F-Tan (Theta) distortion of less than 2% within half the field of view. The graph shows that the maximum distortion of the lens is 0.77%, which meets the design requirements.
[0050] Figure 5 The image shows the lens's transverse chromatic aberration curves. The solid lines represent the transverse chromatic aberration curves for each wavelength at each image height, with a maximum value of 3 μm. The dashed lines represent the transverse chromatic aberration of the Airy disk, which is 9.5 μm. The actual transverse chromatic aberration is less than the Airy disk transverse chromatic aberration, and the design meets the requirements.
[0051] Figure 6 The figure shows the axial aberration curves for each wavelength at various points within the normalized pupil. The maximum axial aberration is 65 μm, and the lens design requires the maximum axial aberration to be less than 100 μm. The lens axial aberration curve meets this requirement.
[0052] Figure 7 The graph shows the focus shift curves. The maximum focus shift for each wavelength is 21 μm, which is less than the 40 μm required by the lens design, thus meeting the design requirements.
[0053] Figure 8The figure shows the field curvature curves. The solid lines in the figure represent the meridional field curvature within the half-field angle of each wavelength, and the dashed lines represent the sagittal field curvature within the half-field angle of each wavelength. The maximum field curvature is 25μm, and the lens design requires a field curvature of less than 60μm. The lens meets the design requirements.
[0054] The above are merely three embodiments of the present invention and are not intended to limit the present invention. Any modifications and substitutions made within the spirit and concept of the present invention shall be protected by the present invention.
Claims
1. A broadband imaging lens with an all-glass spherical surface, characterized in that: The lens comprises five lenses arranged sequentially from the object side to the image side: a first lens with positive optical power, a second lens with negative optical power, a third lens with positive optical power, a fourth lens with positive optical power, and a fifth lens with negative optical power; the first and second lenses are cemented together to form a lens group. Let f1, f2, f3, f4, and f5 be the focal lengths of the first, second, third, fourth, and fifth lenses, respectively; f12 be the focal length of the lens group formed by cementing the first and second lenses together; and f be the focal length of the entire lens. All parameters satisfy the following relationship: 40mm <f<50mm,0.4<f1 / f<0.6,-0.5<f2 / f<-0.3,0.7<f3 / f<0.9,0.8<f4 / f<1.0,-0.5<f5 / f<-0.3,-4.5<f12 / f<-2.5; All the lenses are made of glass, and the first lens is made of the same material as the third lens, and the fourth lens is made of the same material as the fifth lens. The first requirement for the lens material is that the transmittance of the material is greater than 0.8 in the 340 nm-1550 nm band within a thickness of 25 mm. The second lens material requires that its transmittance be greater than 0.3 in the 340 nm-1550 nm wavelength range within a thickness of 25 mm. The fourth lens material requirement is that the transmittance of the material is greater than 0.6 in the 340 nm-1550 nm wavelength range within a thickness of 25 mm.
2. The all-glass spherical broadband imaging lens according to claim 1, wherein each lens includes an object-end optical surface and an image-end optical surface, characterized in that: The object-end optical surface and the image-end optical surface of the lens are both spherical, and the image-end optical surface of the first lens and the object-end optical surface of the second lens are in close contact to form a cemented doublet lens.
3. The all-glass spherical broadband imaging lens according to claim 2, wherein the total length of the lens, i.e. the distance between the center of the optical surface of the first lens object end and the image plane, satisfies the following relationship: 50 mm < TTHI < 65 mm.
4. The all-glass spherical broadband imaging lens according to claim 1, characterized in that, The refractive indices and Abbe numbers of the first lens, the second lens, and the fourth lens satisfy the following relationship: n1 < 1.45, v1 > 90.0, n2 > 1.70, v2 < 55, v4 < 42; where n1 and n2 are the refractive indices of the first lens and the second lens, respectively, and v1, v2, and v4 are the Abbe numbers of the first lens, the second lens, and the fourth lens, respectively.
5. The all-glass spherical broadband imaging lens according to claim 1, characterized in that, Define F# = f / D, where D is the entrance pupil diameter. F# determines the difficulty of lens design and the lens's light throughput; F# satisfies: 3.0 <F#<4.0。 6. A broadband imaging lens with an all-glass spherical surface according to claim 1, characterized in that, R11, R21, R31, R41, and R51 are the radii of curvature of the object-end optical surfaces of the first, second, third, fourth, and fifth lenses, respectively; R12, R22, R32, R42, and R52 are the radii of curvature of the image-end optical surfaces of the first, second, third, fourth, and fifth lenses, respectively; each radius of curvature satisfies the following relationship: 15 mm <R11<30 mm,-25mm<R12<-10mm,R21=R12,50 mm<R22<80 mm,20 mm<R31<40 mm,R32=-R31,30 mm<R41<50 mm,-75 mm<R42<-40 mm,-18 mm<R51<-8 mm,50 mm<R52<70 mm。 7. A broadband imaging lens with an all-glass spherical surface according to claim 1, characterized in that, Let d1, d2, d3, and d4 be the thicknesses of the first lens, second lens, third lens, and fourth lens, respectively; the lenses satisfy the following relationship: 6 mm <d1<10 mm,2 mm<d2<3.5 mm,6.5 mm<d3<9.5 mm,8.0 mm<d4<9.5 mm。