A large aperture spectrum collection lens

Abstract

The present invention discloses a large-aperture spectrum collection lens, which comprises a first lens group, a fixed aperture and a second lens group in sequence from the object side to the image side, wherein the first lens group has positive focal power and can be moved along the optical axis, the second lens group has positive focal power and can be moved along the optical axis, the first lens group comprises a first negative lens group and a first positive lens group, the first negative lens group comprises at least two negative lenses, and the first positive lens group comprises a positive-negative cemented lens with positive focal power, which can achieve a short focal length, a close focusing distance and a large field of view, thereby improving the sensitivity of spectrum collection.

Description

Technical Field

[0001] The invention relates to the technical field of lenses, and in particular to a spectrum collection lens with a large aperture. Background Art

[0002] The functional requirements of spectrometer products are increasingly developing towards a substantial improvement in the sensitivity of spectral detection. In order to meet the improvement in spectral detection sensitivity, on the one hand, the structural quality of the lens is improved, and on the other hand, the sensitivity of the spectrometer signal acquisition sensor CMOS / CCD is improved and the light flux (FNO) of the spectrometer acquisition lens is directly increased. The target size of the existing spectrometer signal acquisition sensor CMOS / CCD is mostly 1 / 2 or 2 / 3 inches, and the aperture FNO is 1.4 to 2.0, which has poor detection sensitivity for weak spectral signals. Summary of the invention

[0003] The purpose of the present invention is to provide a large aperture spectrum collection lens, wherein the first negative lens group is provided with two negative lenses cooperating with a negative-positive cemented lens to achieve a short focal length, a close focusing distance and a large field of view, thereby improving the sensitivity of spectrum collection and solving the problem of poor sensitivity of the spectrum collection lens.

[0004] To achieve this object, the present invention adopts the following technical solutions:

[0005] A large aperture spectrum collection lens, which includes a first lens group, a fixed aperture and a second lens group from the object side to the image side;

[0006] The first lens group has positive refractive power and can be moved along the optical axis;

[0007] The second lens group has positive refractive power and can be moved along the optical axis;

[0008] The first lens group includes a first negative lens group and a first positive lens group, the first negative lens group includes at least two negative lenses, and the first positive lens group includes a positive and negative glued lens with positive focal power;

[0009] The first lens group and the second lens group satisfy the following equation:

[0010] 1<f1 / f2<2; -1<f11 / f1<-0.5;

[0011] Among them, f1 represents the focal length value of the first lens group, f2 represents the focal length value of the second lens group, and f11 represents the focal length value of the first negative lens group.

[0012] Thus, the first lens group can be moved to realize the focusing function, the second lens group can be moved to realize the magnification change, and the structural combination of the negative first negative lens group of the first lens group and the first positive lens group can realize short focal length, close focusing distance and large field angle, improve the sensitivity of spectral acquisition, and the focal length of the first lens group and the focal length of the second lens group satisfy the relationship of 1<f1 / f2<2, so that the lens meets the back working distance of the optical system, and the focal length of the first negative lens group and the total focal length of the first lens group satisfy the relationship of -1<f11 / f1<-0.5, so that the optical system can bear a field angle.

[0013] In some embodiments, the second lens group includes at least one negative lens, and includes a positive-negative cemented lens with positive power and a negative-positive cemented lens with negative power.

[0014] Therefore, the negative lens is the eighth lens, which can effectively balance the coma and astigmatism of the front and rear lens groups, so that the sensitivity of the matching tolerance of the front and rear lens groups is greatly reduced. The positive and negative glued lens is composed of the ninth lens and the tenth lens, and the negative and positive glued lens is composed of the eleventh lens and the twelfth lens. The combination of the two glued lenses can correct chromatic aberration and distortion.

[0015] In some embodiments, the first negative lens group further includes a negative-positive cemented lens with negative optical power.

[0016] Therefore, the first lens group is provided with two cemented lenses, and the light beam is first continuously gathered and then diffused, and the light path is gourd-shaped, so that the astigmatism and field curvature of the first lens group are smaller, and the tolerance sensitivity of the front and rear lens groups can be reduced.

[0017] In some embodiments, the back working distance of the lens is BFL, and the focal length of the lens is f, satisfying the following formula: 0.5<BFL / f<1.

[0018] Thus, the lens forms a reverse telephoto optical path structure to ensure a sufficient rear working distance.

[0019] In some embodiments, the refractive index of the sixth lens of the first lens group is between 1.85 and 1.95.

[0020] Therefore, a higher refractive index can reduce the thickness of the lens, making it more compact and lightweight.

[0021] In some embodiments, the refractive index of the tenth lens of the second lens group is between 1.70 and 1.80.

[0022] Therefore, a higher refractive index can reduce the thickness of the lens, making it more compact and lightweight.

[0023] In some embodiments, the first lens group includes at least three lenses having a refractive index greater than 1.8.

[0024] Thus, when light with a large angle enters the system aperture, the deflection angle is reduced. At the same time, the total length of the optical path can be effectively shortened and the number of lenses can be reduced to achieve a compact optical structure. Preferably, the refractive index of the fifth, sixth and seventh lenses in this solution is greater than 1.8, and the refractive index of the remaining lenses can also be set to be greater than 1.8.

[0025] In some embodiments, the total length from the first mirror surface to the last mirror surface of the lens is between 90 and 100 mm, and the maximum aperture of the lens is between 32 and 36 mm.

[0026] Therefore, the maximum aperture of the lens is the aperture of the first lens group, and the overall space of the lens is compact and lightweight.

[0027] In some embodiments, the lens can be applied to a spectrometer and can be used in conjunction with a large aperture light flux of F0.95 and a large target area of ​​1 inch sensor.

[0028] As a result, the lens can better meet the high-sensitivity detection of weak spectral signals and improve the sensitivity of the spectrometer.

[0029] The beneficial effects of the present invention are as follows: the first negative lens group is provided with two negative lenses and a negative-positive cemented lens, so as to achieve a short focal length, a close focusing distance and a large field of view, thereby improving the sensitivity of spectrum collection, and in combination with the positive-negative cemented lens of the first positive lens group, it is beneficial to correct chromatic aberration and distortion;

[0030] The eighth lens of the second lens group can effectively balance the coma and astigmatism of the front and rear lens groups, so that the sensitivity of the matching tolerance of the front and rear lens groups is greatly reduced. In addition, two cemented lenses are also provided to facilitate the correction of chromatic aberration and distortion.

[0031] The lens is equipped with multiple lenses with large refractive indices, which can effectively bend wide-angle incident light, reduce the deflection angle when large-angle light enters the system aperture, and effectively shorten the total length of the optical path and reduce the number of lenses. It has a compact structure, can achieve short focal length and close focusing distance, can take into account low distortion, full field of view, high definition, large aperture and small size, and can improve the detection sensitivity of weak spectral signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a structural diagram of a large aperture spectrum collection lens of the present invention;

[0033] Figure 2 A schematic diagram of axial chromatic aberration of a large aperture spectrum collection lens of the present invention;

[0034] Figure 3 A schematic diagram of vertical axis chromatic aberration of a large aperture spectrum collection lens of the present invention;

[0035] Figure 4 It is a schematic diagram of field curvature distortion of a large aperture spectrum collection lens of the present invention;

[0036] Figure 5 A schematic diagram of light aberration of a large aperture spectrum collection lens of the present invention;

[0037] Figure 6 A schematic diagram of a diffuse spot of a large aperture spectrum collection lens of the present invention;

[0038] Figure 7 It is a schematic diagram of the MTF of a large aperture spectrum collection lens of the present invention;

[0039] Figure 8 A schematic diagram of MTF and field of view of a large aperture spectrum collection lens of the present invention;

[0040] Among them: G1-first lens group; G2-second lens group; G11-first negative lens group; G12-first positive lens group; L1-first lens; L2-second lens; L3-third lens; L4-fourth lens; L5-fifth lens; L6-sixth lens; L7-seventh lens; L8-eighth lens; L9-ninth lens; L10-tenth lens; L11-eleventh lens; L12-twelfth lens; L13-thirteenth lens; L14-fourteenth lens. DETAILED DESCRIPTION

[0041] The present invention will be further described in detail below in conjunction with the accompanying drawings.

[0042] refer to Figure 1 , a large aperture spectrum collection lens, which includes a first lens group G1, a fixed aperture STO and a second lens group G2 from the object side to the image side;

[0043] The first lens group G1 has positive refractive power and can be moved along the optical axis.

[0044] The second lens group G2 has positive refractive power and can be moved along the optical axis.

[0045] The first lens group G1 includes a first negative lens group G11 and a first positive lens group G12, the first negative lens group G11 includes at least two negative lenses, and the first positive lens group G12 includes a positive and negative cemented lens with positive focal power;

[0046] The first lens group G1 and the second lens group G2 satisfy the following equation:

[0047] 1<f1 / f2<2; -1<f11 / f1<-0.5;

[0048] Among them, f1 represents the focal length value of the first lens group G1, f2 represents the focal length value of the second lens group G2, and f11 represents the focal length value of the first negative lens group G11.

[0049] To further illustrate, the second lens group G2 includes at least one negative lens, and includes a positive-negative cemented lens with positive power and a negative-positive cemented lens with negative power.

[0050] To further illustrate, the first negative lens group G11 also includes a negative-positive cemented lens with negative optical power.

[0051] Further explanation: the back working distance of the lens is BFL, the focal length of the lens is f, and the following formula is satisfied: 0.5<BFL / f<1. The lens forms a reverse telephoto optical path structure to ensure a sufficient back working distance.

[0052] To further illustrate, the refractive index of the sixth lens L6 of the first lens group G1 is between 1.85 and 1.95.

[0053] To further illustrate, the refractive index of the tenth lens L10 of the second lens group G2 is between 1.70 and 1.80.

[0054] To further illustrate, the first lens group G1 includes at least three lenses with a refractive index greater than 1.8.

[0055] It is further specified that the total length from the first mirror surface to the last mirror surface of the lens is between 90 and 100 mm, and the maximum aperture of the lens is between 32 and 36 mm.

[0056] It is further explained that the lens can be applied to spectrometers and can be used with a large aperture light flux of F0.95 and a large target area of ​​1 inch sensor.

[0057] Working principle:

[0058] The lens comprises a first lens group G1 and a second lens group G2. The first lens group G1 can move to adjust focus, and the second lens group G2 can move to change magnification.

[0059] The first lens group G1 includes a first negative lens group G11 and a first positive lens group G12. The first negative lens group G11 includes, from the object side to the image side, a first lens L1 with negative optical focal length, a second lens L2 with negative optical focal length, and a negative-positive cemented lens with negative optical focal length, wherein the cemented lens is formed by cementing a third lens L3 with negative optical focal length and a fourth lens L4 with positive optical focal length. The first negative lens group G11 can achieve a short focal length, a close focusing distance, and a large field of view through the two negative lenses and the negative cemented lens structure, and can better collect spectra. The sensitivity of spectrum collection is improved through the combined structure of the lenses.

[0060] The first lens group G1 may also be provided with a plurality of negative lenses, which can further improve the short focal length close focusing distance and the field of view angle.

[0061] The first positive lens group G12 includes, from the object side to the image side, a fifth lens L5 with positive optical power and a positive and negative cemented lens with positive optical power, wherein the cemented lens is formed by cementing a sixth lens L6 with positive optical power and a seventh lens L7 with negative optical power. The light beam is first continuously gathered in the first lens group G1 and then diffused. The light path is shaped like a gourd, so that the astigmatism and field curvature of the first lens group G1 are smaller, and the tolerance sensitivity of the front and rear lens groups can be reduced. In addition, the matching structure of the cemented lens of the first negative lens group G11 and the cemented lens of the first positive lens group G12 can correct chromatic aberration and distortion, and improve the resolution of imaging.

[0062] The second lens group G2 includes, from the object side to the image side, an eighth lens L8 with negative optical power, a positive-negative cemented lens with positive optical power, a negative-positive cemented lens with negative optical power, a thirteenth lens L13 with positive optical power and a fourteenth lens L14 with positive optical power, among which the ninth lens L9 with positive optical power and the tenth lens L10 with negative optical power are cemented into a positive-negative cemented lens, and the eleventh lens L11 with negative optical power and the twelfth lens L12 with positive optical power are cemented into a negative-positive cemented lens.

[0063] The first lens L1 is a negative lens, which can effectively balance the coma and astigmatism of the front and rear lens groups, so that the sensitivity of the matching tolerance of the front and rear lens groups is greatly reduced. The first lens group G1 can be provided with a plurality of negative lenses.

[0064] The two cemented lenses are arranged roughly opposite to each other, and this structural combination can correct chromatic aberration and distortion.

[0065] The lens can be assembled in optical instruments such as spectrometers, and can be used in conjunction with a large aperture light flux of F0.95 and a large target surface of 1-inch sensor to further improve the high-sensitivity detection of weak spectral signals.

[0066] Reference is made to Table 1 below, which shows numerical data of certain embodiments, such as the radius of curvature, thickness, refractive index and dispersion coefficient of the lens, wherein S1-S25 represent the mirror surface of the lens from the object side to the image side in sequence, and the unit of numerical data is usually "mm".

[0067] Table 1:

[0068]

[0069]

[0070] Figure 2 is an on-axis spherical aberration diagram of an embodiment of the present disclosure, Figure 3 is a vertical axis chromatic aberration diagram of an embodiment of the present disclosure, Figure 4is a field curvature distortion diagram of an embodiment of the present disclosure, Figure 5 is a light aberration diagram of an embodiment of the present disclosure, Figure 6 is the diffusion pattern of the embodiment of the present disclosure, Figure 7 is an MTF diagram of an embodiment of the present disclosure, Figure 8 This is the MTF and field of view diagram of the embodiment of the present invention. It can be seen from the above diagram that the lens of the present invention has a compact structure, can achieve short focal length and close focusing distance, can take into account low distortion and full field of view high definition, can achieve large clear aperture and small volume, can improve the detection sensitivity of weak spectral signals, and the lens aberration is well corrected, and good imaging effect can be achieved in the whole field of view, and can achieve short focal length, large clear aperture, small volume, low distortion, and full field of view high definition image quality.

[0071] The above disclosure is only some embodiments of the present invention. For those skilled in the art, several modifications and improvements can be made without departing from the creative concept of the present invention, which all belong to the protection scope of the invention.

Claims

1. A large aperture spectrum collection lens, characterized in that: The lens comprises, from the object side to the image side, a first lens group (G1), a fixed aperture and a second lens group (G2); The first lens group (G1) has positive refractive power and is movable along the optical axis; The second lens group (G2) has positive refractive power and is movable along the optical axis; The first lens group (G1) includes a first negative lens group (G11) and a first positive lens group (G12); The first negative lens group (G11) comprises a first lens (L1) with negative optical power, a second lens (L2) with negative optical power and a negative-positive cemented lens with negative optical power, wherein the cemented lens is formed by cementing a third lens (L3) with negative optical power and a fourth lens (L4) with positive optical power; The first positive lens group (G12) comprises a fifth lens (L5) with positive focal power and a positive-negative cemented lens with positive focal power, wherein the cemented lens is formed by cementing a sixth lens (L6) with positive focal power and a seventh lens (L7) with negative focal power; The second lens group (G2) comprises an eighth lens (L8) with negative optical power, a positive-negative cemented lens with positive optical power, a negative-positive cemented lens with negative optical power, a thirteenth lens (L13) with positive optical power and a fourteenth lens (L14) with positive optical power, wherein a ninth lens (L9) with positive optical power and a tenth lens (L10) with negative optical power are cemented into a positive-negative cemented lens, and an eleventh lens (L11) with negative optical power and a twelfth lens (L12) with positive optical power are cemented into a negative-positive cemented lens; The first lens group (G1) and the second lens group (G2) satisfy the following formula: 1<f1 / f2<2; -1<f11 / f1<-0.5; Among them, f1 represents the focal length value of the first lens group (G1), f2 represents the focal length value of the second lens group (G2), and f11 represents the focal length value of the first negative lens group (G11).

2. The large aperture spectrum collection lens according to claim 1, characterized in that: The back working distance of the lens is BFL, and the focal length of the lens is f, which satisfies the following formula: 0.5<BFL / f<1.

3. The large aperture spectrum collection lens according to claim 1, characterized in that: The refractive index of the sixth lens (L6) of the first lens group (G1) is between 1.85 and 1.

95.

4. The large aperture spectrum collection lens according to claim 1, characterized in that: The refractive index of the tenth lens (L10) of the second lens group (G2) is between 1.70 and 1.

80.

5. The large aperture spectrum collection lens according to claim 1, characterized in that: The first lens group (G1) includes at least three lenses with a refractive index greater than 1.

8.

6. The large aperture spectrum collection lens according to claim 1, characterized in that: The total length from the first mirror surface to the last mirror surface of the lens is between 90 and 100 mm, and the maximum aperture of the lens is between 32 and 36 mm.

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