A slender probe macro lens

Abstract

The present invention discloses a slender probe macro lens comprising, from the object side to the image side, an objective lens OBJ, a single relay lens group Relay, and a magnifying lens group Macro. When an object approaches from an infinite distance, some lenses of the magnifying lens group move to achieve focus. The present invention is convenient and quick to use, and can achieve a high-performance, excellent imaging special wide-angle probe macro lens through the slender probe macro lens composed of the objective lens group OBJ, the relay lens group Relay, and the magnifying and focusing lens group MACRO.

Description

Technical Field

[0001] The present invention relates to the technical field of macro photography, and in particular to a slender probe macro lens. Background Art

[0002] Currently, known rigid endoscopes have a slender body, allowing them to capture images in confined spaces. However, due to the complexity and manufacturing difficulties of the relay lenses, the image field is too small to be used on APS-C and full-frame cameras and camcorders. Furthermore, due to the lack of a focus and aperture system, they cannot achieve good imaging at long distances or in macro conditions. For example, in the well-known Japanese Patent Laid-Open No. 5-297272, the objective lens consists of two negative lenses connected to a prism, followed by a positive-negative cemented lens, then a negative-positive cemented lens, and finally several relay lenses. While this slender structure allows for capturing images in narrow, dark areas and achieving unique photographic perspectives, the excessive number of lenses in this combination makes manufacturing complex and costly. Furthermore, the image field is too small to cover the large field of view of interchangeable cameras and camcorders. Furthermore, if digitally magnified, performance degrades dramatically, making it unsuitable for photography and videography.

[0003] Ordinary macro lenses are too thick in diameter and too short in length to be used for shooting in narrow caves, especially the inner cavities of objects, or damp and dim places where they cannot be inserted for shooting. Summary of the Invention

[0004] The main purpose of the present invention is to provide a slender probe macro lens, which can effectively solve the problem that existing macro lenses cannot be small and slender and cannot capture narrow places, while overcoming the problems of small image field, low image quality, high cost and difficulty in manufacturing similar to medical rigid tube endoscopes.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] A slender probe macro lens comprises, from the object side to the image side, an objective lens OBJ, a single relay lens group Relay, and a lens group Macro for magnification;

[0007] When an object approaches from an infinite distance, some lenses of the magnifying lens group move to achieve focus, and the following condition (1) is satisfied:

[0008] 0.5<Ymax / F<0.95 (1);

[0009] in,

[0010] Ymax: Infinity state, maximum paraxial image (Ymax = F × Tanω);

[0011] ω: half picture angle;

[0012] F: The focal length of the entire optical system at infinity.

[0013] The focal length of the objective lens OBJ is Fw. The structure of the objective lens OBJ is a negative refractive power lens Ga starting from the object side and a positive refractive power lens Gb on the image side, which satisfies the conditions (2) and (3).

[0014] 1.5<Ymax / Fw<5.0 (2);

[0015] 1.5<|FGb / FGa|<7 (3);

[0016] in,

[0017] Ymax: Infinity state, maximum paraxial image (Ymax = F × Tanω);

[0018] ω: half picture angle;

[0019] Fw: focal length of objective lens OBJ;

[0020] FGa: Focal length of the most negative diopter lens on the object side of the objective lens OBJ;

[0021] FGb: Focal length of the most image-facing side of the objective lens OBJ.

[0022] Conditions (4) and (5) are also satisfied;

[0023] 1.5<F / FM<3.0 (4);

[0024] 1.0<FM / Fw<3.0 (5);

[0025] in,

[0026] FM: Focal length of the magnifying lens group at infinity;

[0027] F: focal length of the entire optical system at infinity;

[0028] Fw: focal length of objective lens OBJ.

[0029] It also satisfies condition (6);

[0030] 3<RL / F<10 (6);

[0031] in,

[0032] RL: The length of the relay lens group;

[0033] F: The focal length of the entire optical system at infinity.

[0034] If the upper limit of the conditional expression 0.5<Ymax / F<0.95(1) is exceeded, the refractive power of the objective lens OBJ becomes very strong. Although an ultra-wide angle of view can be achieved, the volume of the objective lens increases sharply, making it impossible to achieve a slender lens structure. If the lower limit of the conditional expression (1) is exceeded, the refractive power of the objective lens OBJ becomes very weak. Although miniaturization is easily achieved, the angle of view is too small, the shooting range is narrow, and the wide-angle macro effect cannot be achieved.

[0035] If the upper limit of the conditional expression 1.5<Ymax / Fw<5.0(2) is exceeded, the focal length of the entire optical system is too short, resulting in a wide angle of view, making it difficult to achieve miniaturization. If the lower limit of the conditional expression (2) is exceeded, although performance can be easily achieved for miniaturization, the angle of view is too small, the shooting range is too narrow, and the wide-angle macro effect cannot be achieved.

[0036] If the upper limit of the conditional expression 1.5<|FGb / FGa|<7(3) is exceeded, the refractive power of the first lens on the most object side of the objective lens OBJ is too strong. Although it is easy to achieve an ultra-wide angle of view, miniaturization is very difficult. At the same time, it is easy to produce various difficult-to-correct image fields, making it difficult to achieve high image quality. If the lower limit of the conditional expression (3) is exceeded, the refractive power of the first lens on the most object side of the objective lens OBJ is too weak. Although high performance and a slender volume are easy to achieve, the angle of view is too narrow, and the wide-angle macro effect cannot be achieved.

[0037] If the upper limit of the conditional expression 1.5<F / FM<3.0(4) is exceeded, the refractive power of the magnifying lens group Macro is too strong, the magnification ratio is too large, and various aberrations are difficult to correct. At the same time, due to the excessive magnification ratio, the actual aperture will become very dark, and the image quality will be greatly reduced due to optical diffraction. If the lower limit of the conditional expression (4) is exceeded, the refractive power of the magnifying lens group Macro is too weak, and the magnification ratio is insufficient. If the image is to cover a large frame, the entire Macro lens group will be extremely large, making it difficult to achieve the requirement of miniaturization.

[0038] If the upper limit of the conditional expression 1.0<FM / Fw<3.0(5) is exceeded, the refractive power of the objective lens OBJ is too strong. Although it is easy to achieve the ultra-wide-angle effect, the size of the objective lens increases, and it becomes difficult to correct various aberrations. If the lower limit of the conditional expression (5) is exceeded, the refractive power of the objective lens OBJ is too weak. Although miniaturization and high performance are relatively easy to achieve, the picture angle will become very narrow, and the wide-angle macro effect cannot be achieved.

[0039] If the upper limit of the conditional expression 3 < RL / F < 10 (6) is exceeded, the length of the relay lens group is too long. Although it is easy to achieve the required lens length, the diameter will become significantly thicker, making it difficult to achieve the slender requirement. At the same time, various aberrations are also likely to occur. Alternatively, the focal length of the optical system is too short. Although it is easy to achieve the ultra-wide angle of view, the wide angle will cause the volume of the objective lens to increase and the diameter of the entire lens will also become thicker. If the lower limit of the condition (6) is exceeded, the length of the relay lens group is too short, making it difficult to achieve the slender lens requirement. Alternatively, the focal length of the entire optical system is too long, resulting in a narrow angle of view and an inability to achieve the wide-angle macro effect.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] The invention relates to a slender probe macro lens, which is composed of an objective lens group OBJ, a relay lens group Relay and a magnifying and focusing lens group MACRO, and realizes a special wide-angle probe macro lens with high performance and excellent imaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 Schematic diagram of the slender probe macro lens provided in Example 1 of the present invention.

[0043] Figure 2 These are the spherical aberration, field curvature, distortion, and lateral chromatic aberration at infinity and constant magnification in Example 1.

[0044] Figure 3 Schematic diagram of the slender probe macro lens provided in Example 2 of the present invention.

[0045] Figure 4 These are the spherical aberration, field curvature, distortion, and lateral chromatic aberration at infinity and constant magnification in Example 2.

[0046] Figure 5 Schematic diagram of the slender probe macro lens provided in Example 3 of the present invention.

[0047] Figure 6 These are the spherical aberration, field curvature, distortion, and lateral chromatic aberration at infinity and constant magnification in Example 3. DETAILED DESCRIPTION

[0048] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below in conjunction with specific implementation methods.

[0049] Example 1

[0050] like Figure 1As shown, a slender probe macro lens is characterized in that it includes an objective lens OBJ, a single relay lens group Relay, and a lens group Macro that plays a magnifying role from the object side to the image side; when the object approaches from an infinite distance, some lenses of the magnifying lens group move to achieve focusing.

[0051] The spherical aberration, field curvature aberration, distortion aberration and lateral chromatic aberration at infinity and equal photographic magnification of Example 1 are as follows: Figure 2 shown.

[0052] Focus distance: 26.061

[0053] Fno:13.5

[0054] Half angle of view ω: 41.5

[0055] The data of Example 1 are as follows:

[0056]

[0057]

[0058]

[0059] Where, R (mm): radius of curvature of each surface;

[0060] D (mm): the distance between lenses and the thickness of the lenses;

[0061] Nd: refractive index of each glass at d line;

[0062] Vd: Abbe number of glass.

[0063] Example 2

[0064] like Figure 3 As shown, a slender probe macro lens is characterized in that it includes an objective lens OBJ, a single relay lens group Relay, and a lens group Macro that plays a magnifying role from the object side to the image side; when the object approaches from an infinite distance, some lenses of the magnifying lens group move to achieve focusing.

[0065] The spherical aberration, field curvature aberration, distortion aberration and lateral chromatic aberration at infinity and equal photographic magnification of Example 2 are as follows: Figure 4 shown.

[0066] Focus distance: 28.078

[0067] Fno:13.5

[0068] Half angle of view ω: 38.96

[0069]

[0070]

[0071]

[0072] focal distance 28.0775 0.25 times 1.0 times D(33) 49.6282 48.6438 45.6941 D(35) 69.7742 70.7586 73.7083 BF 38.4900 38.4900 38.4900

[0073] Where, R (mm): radius of curvature of each surface;

[0074] D (mm): the distance between lenses and the thickness of the lenses;

[0075] Nd: refractive index of each glass at d line;

[0076] Vd: Abbe number of glass;

[0077] Example 3

[0078] like Figure 5 As shown, a slender probe macro lens is characterized in that it includes an objective lens OBJ, a single relay lens group Relay, and a lens group Macro that plays a magnifying role from the object side to the image side; when the object approaches from an infinite distance, some lenses of the magnifying lens group move to achieve focusing.

[0079] The spherical aberration, field curvature aberration, distortion aberration and lateral chromatic aberration at infinity and equal photographic magnification of Example 3 are as follows: Figure 6 shown.

[0080] Focus distance: 32.144

[0081] Fno: 13.5

[0082] Half angle of view ω: 34.46

[0083]

[0084]

[0085] focal distance 32.1443 28.4460 21.2399 D(33) 45.1429 44.0911 40.9284 D(35) 70.5319 71.5837 74.7464 BF 38.5753 38.5753 38.5753

[0086] Where, R (mm): radius of curvature of each surface;

[0087] D (mm): the distance between lenses and the thickness of the lenses;

[0088] Nd: refractive index of each glass at d line;

[0089] Vd: Abbe number of glass;

[0090] Conditions satisfied:

[0091] Example 1 Example 2 Example 3 Conditional expression (1): 0.5≤Ymax / F≤0.95 0.885 0.809 0.686 Conditional expression (2): 1.5≤F / L1≤5.0 3.880 3.558 2.986 Conditional formula (3): 1.5≤|FGb / Fga|≤7 4.091 4.391 2.182 Conditional expression (4): 1.5≤F / FM≤3.0 1.984 2.109 2.472 Conditional expression (5): 1.0≤FM / Fw≤3.0 2.210 2.086 1.760 Conditional expression (6): 3≤RL / F≤10 5.935 5.463 4.758

[0092] In combination with the lens structures given in the above embodiments 1-3 and the corresponding test data, it can be seen that the present invention provides a slender probe macro lens composed of an objective lens group OBJ, a relay lens group Relay and a magnifying and focusing lens group MACRO, which achieves high performance and excellent imaging. Special wide-angle probe macro lens can be widely used in digital camera lenses, video camera lenses, especially in technical fields such as macro photography.

[0093] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A slender probe macro lens, characterized in that: From the object side to the image side, it includes the objective lens OBJ, a single relay lens group Relay, and a lens group Macro that plays a magnifying role; When an object approaches from an infinite distance, some of the lenses in the magnifying lens group move to achieve focus. The focal length of the objective lens OBJ is Fw. The structure of the objective lens OBJ is a negative refractive power lens Ga starting from the object side and a positive refractive power lens Gb on the image side, and the following conditions (1), (2), (3), (4), (5) and (6) are satisfied: 0.5<Ymax / F<0.95 (1); 1.5<Ymax / Fw<5.0 (2); 1.5<|FGb / FGa|<7 (3); 1.5<F / FM<3.0 (4); 1.0<FM / Fw<3.0 (5); 3<RL / F<10 (6); in, Ymax: Infinity state, the maximum image on the paraxial axis, where Ymax = F × Tanω; ω: half picture angle; F: focal length of the entire optical system at infinity; Fw: focal length of objective lens OBJ; FGa: Focal length of the most negative diopter lens on the object side of the objective lens OBJ; FGb: focal length of the lens on the most image side of the objective lens OBJ; FM: Focal length of the magnifying lens group at infinity; RL: The length of the relay lens group.

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