A triple-element moving large variable magnification infrared zoom lens and its imaging method

Abstract

The present invention provides a three-element, mobile, high-zoom infrared zoom lens. The lens comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens, arranged in sequence from front to back along the incident light path. The first lens is a positive lens, the second lens is a negative lens, the third lens is a positive lens, the fourth lens is a negative lens, the fifth lens is a negative lens, and the sixth lens is a positive lens. The present invention features a rational design. By selecting high-refractive-index glass as the material for the negative lens, high-grade spherical aberration at both on-axis and off-axis points in the system is corrected. By selecting suitable glass as the material for the positive lens, the system's aberrations are reduced, improving its resolution.

Description

Technical Field

[0001] The invention relates to a three-component moving large-magnification infrared zoom lens. Background Art

[0002] In infrared imaging systems, optical systems with continuous zoom or multi-field-of-view switching capabilities offer greater advantages than traditional single-field-of-view optical systems in practical applications such as remote sensing, early warning, reconnaissance and aiming, and imaging guidance. With a large field of view, they can search for targets over a large area, while with a small field of view, they can detect, identify, track, and aim at the searched targets. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to propose a three-component mobile large-zoom infrared zoom lens, which achieves a minimum focal length of 15mm and a maximum focal length of 300mm. It can be matched with a 640x512@15μm medium-wave cooled infrared detector, and can effectively search and track long-distance targets, low-illuminance targets, and concealed targets. It can be applied to remote sensing, early warning, reconnaissance and sighting, imaging guidance and other demand scenarios.

[0004] The present invention is implemented by the following scheme: a three-component movable large-magnification infrared zoom lens, wherein the lens is composed of a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens arranged in sequence from front to back along the incident light path, wherein the first lens is a positive lens, the second lens is a negative lens, the third lens is a positive lens, the fourth lens is a negative lens, the fifth lens is a negative lens, and the sixth lens is a positive lens.

[0005] Furthermore, the first lens and the third lens are made of silicon single crystal, and the second lens, the fourth lens, the fifth lens and the sixth lens are made of germanium single crystal.

[0006] Furthermore, the focal length of the lens is f, and the focal lengths of the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens are f respectively. A 、f B 、f C 、f D 、f E1 、f E2 , the focal length at the telephoto position is f L , the focal length at the short focal length is f S , where f, f A 、f B 、f C 、f D 、f E1 、f E2 、f L 、f S The following relationship is satisfied: 0.23<|f A / f L |<0.5,0.03<|f B / f L |<0.05,0.02<|f C / f L |<0.06,0.045<|f D / f L |<0.085,0.06<|f E1 / f L |<0.12,0.01<|f E2 / f L |<0.035, where 3<|f A / f S |<5, 0.43<|f B / f S |<0.74,0.55<|f C / f S |<1.2,1.45<|f D / f S |<1.78,1.5<|f E1 / f S |<2.1,0.32<|f E2 / f S |<0.58.

[0007] Furthermore, the air gap between the first lens and the second lens is 19.4mm-44mm; the air gap between the second lens and the third lens is 45.0mm-2.2mm; the air gap between the third lens and the fourth lens is 2.5mm-9.2mm; the air gap between the fourth lens and the fifth lens is 2.5mm-14.1mm; and the air gap between the fifth lens and the sixth lens is 11.0mm.

[0008] Furthermore, the first lens satisfies the relationship: N d =3.42, V d =236; the second lens satisfies the relationship: N d =4.00, V d =107; the third lens satisfies the relationship: N d =3.42, V d =236; the fourth lens satisfies the relationship: N d =4.00, V d =107; the fifth lens satisfies the relationship: N d =4.00, V d =107; the sixth lens satisfies the relationship: N d =4.00, V d =107; where Nd is the refractive index, V d is the Abbe constant.

[0009] Furthermore, the operating wavelength band of the lens is 3.7-4.8 μm.

[0010] Furthermore, the relative aperture of the lens is 1 / 4, and it is a medium-wave infrared lens with a 20x zoom ratio.

[0011] Furthermore, it also includes a lens barrel structure, which includes a main lens barrel, a front lens seat is installed in the front section of the main lens barrel, and a first lens is installed in the front lens seat. The rear section of the lens barrel structure is sequentially provided with a zoom slide, a first compensation slide, and a second compensation slide from front to back, and the second lens, the third lens, and the fourth lens are respectively installed in the zoom slide, the first compensation slide, and the second compensation slide. A flange seat is installed on the rear end of the main lens barrel, and a fifth lens is installed in the front section of the flange seat. A focusing lens seat is installed in the rear section of the flange seat, and a sixth lens is installed in the focusing lens seat.

[0012] An imaging method for a three-component mobile large-magnification infrared zoom lens: light from the object side passes through a first lens, a second lens, an aperture, a third lens, a fourth lens, a fifth lens, and a sixth lens in sequence to form an image on an imaging surface.

[0013] Compared with the existing technology, the present invention has the following beneficial effects: it achieves a minimum focal length of 15mm and a maximum focal length of 300mm, can match a 640x512@15μm medium-wave cooled infrared detector, can effectively search and track long-distance targets, low-illumination targets, and hidden targets, and can be applied to remote sensing, early warning, reconnaissance and aiming, imaging guidance and other demand scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a schematic diagram of the optical structure of an embodiment of the present invention;

[0015] Figure 2 is a short-focus MTF diagram of an embodiment of the present invention;

[0016] Figure 3 2. This is a telephoto MTF vertical axis chromatic aberration diagram of an embodiment of the present invention;

[0017] Figure 4 It is a structural diagram of an embodiment of the present invention.

[0018] In the figure: A-first lens, B-second lens, C-third lens, D-fourth lens, E-1-fifth lens, E-2-sixth lens; 1. first lens, 2. front group pressure ring, 3. A-plate pressure ring, 4. front group lens mount, 5. main lens mount, 6. zoom lens mount, 7. zoom pressure ring, 8. second lens, 9. zoom slide, 10. cam, 11. first compensating slide, 12. third lens, 13. first compensating lens mount, 14. first compensating pressure ring, 15. second compensating slide, 16. second compensating lens mount, 17. flange mount, 18. focusing ring, 19. focusing mount, 20. focusing lens mount, 21. second rear group pressure ring, 22. focusing lens mount pressure ring, 23. fifth lens, 24. first rear group pressure ring, 25. sixth lens, 26. second compensating pressure ring, 27. fourth lens. DETAILED DESCRIPTION

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0020] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0021] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0022] like Figure 1 、 4 As shown, this embodiment provides a three-element mobile large zoom ratio infrared zoom lens, which is composed of a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens arranged in sequence from front to back along the incident light path. The first lens is a positive lens, the second lens is a negative lens, the third lens is a positive lens, the fourth lens is a negative lens, the fifth lens is a negative lens, and the sixth lens is a positive lens. By selecting high-refractive-index glass as the material for the negative lens, the high-order spherical aberration of the system's on-axis and off-axis points is corrected; by selecting suitable glass as the material for the positive lens, the system's aberration is reduced and the system's resolution is improved. Figure 2 , Figure 3 It can be seen that the system has good imaging quality.

[0023] In this embodiment, the first lens and the third lens are made of silicon single crystal, and the second lens, the fourth lens, the fifth lens, and the sixth lens are made of germanium single crystal.

[0024] In this embodiment, the focal length of the lens is f, and the focal lengths of the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens are f respectively. A 、f B 、f C 、f D 、f E1 、f E2 , the focal length at the telephoto position is f L , the focal length at the short focal length is f S , where f, f A 、f B 、f C 、f D 、f E1 、f E2 、f L 、f S The following relationship is satisfied: 0.23<|f A / f L |<0.5,0.03<|f B / f L |<0.05,0.02<|f C / f L |<0.06,0.045<|f D / f L |<0.085,0.06<|f E1 / f L |<0.12,0.01<|f E2 / f L |<0.035, where 3<|f A / f S |<5, 0.43<|f B / f S |<0.74,0.55<|f C / f S |<1.2,1.45<|f D / f S |<1.78,1.5<|f E1 / f S |<2.1,0.32<|f E2 / f S |<0.58.

[0025] In this embodiment, the air gap between the first lens and the second lens is 19.4 mm-44 mm; the air gap between the second lens and the third lens is 45.0 mm-2.2 mm; the air gap between the third lens and the fourth lens is 2.5 mm-9.2 mm; the air gap between the fourth lens and the fifth lens is 2.5 mm-14.1 mm; and the air gap between the fifth lens and the sixth lens is 11.0 mm.

[0026] In this embodiment, the first lens satisfies the relationship: N d =3.42, V d =236; the second lens satisfies the relationship: N d =4.00, V d =107; the third lens satisfies the relationship: N d =3.42, V d =236; the fourth lens satisfies the relationship: N d =4.00, V d =107; the fifth lens satisfies the relationship: N d =4.00, V d =107; the sixth lens satisfies the relationship: N d =4.00, V d =107; where N d is the refractive index, V d is the Abbe constant.

[0027] In this embodiment, the operating wavelength band of the lens is 3.7-4.8 μm.

[0028] In this embodiment, the relative aperture of the lens is 1 / 4, and the lens is a medium-wave infrared lens with a 20x zoom ratio.

[0029] In this embodiment, the parameters of each lens are shown in the following table:

[0030] surface Curvature radius R(mm) Thickness (mm) Refractive index n Abbe number 1 60≤R≤70 8.5 3.42 236 2 95≤R≤105 19.5 1.0 3 340≤R≤350 2.0 4.00 107 4 25≤R≤35 45.0 1.0 5 45≤R≤55 5.2 3.42 236 6 -75≤R≤-65 2.5 1.0 7 -45≤R≤-35 1.8 4.00 107 8 -110≤R≤-100 2.5 1.0 9 5≤R≤10 5.8 4.00 107 10 5≤R≤10 11.0 1.0 11 95≤R≤105 3.0 4.00 107 12 -30≤R≤-20 26.5 1.0

[0031] In this embodiment, a lens barrel structure is also included, wherein the lens barrel structure includes a main lens barrel, a front lens seat is installed in the front section of the main lens barrel, a first lens is installed in the front lens seat, a zoom slide, a first compensation slide, and a second compensation slide are sequentially arranged on the rear section of the lens barrel structure from front to rear, and the zoom slide, the first compensation slide, and the second compensation slide are respectively installed with the second lens, the third lens, and the fourth lens; a flange seat is installed on the rear end of the main lens barrel, a fifth lens is installed in the front section of the flange seat, a focusing lens seat is installed in the rear section of the flange seat, and a sixth lens is installed in the focusing lens seat; the lens barrel structure adopts the existing three-component mobile zoom lens barrel. Since it is not the invention point of this application, the basic mechanism is described below, specifically:

[0032] The main mirror mount is equipped with the front group mirror mount, the first lens is equipped with the front group mirror mount, which is pressed with the A-piece pressure ring and then locked with the front group pressure ring. The front section of the main mirror mount is equipped with a zoom slide, the zoom lens mount is equipped with the zoom lens mount, the second lens is equipped with the zoom lens mount and locked with the zoom pressure ring. The middle section of the main mirror mount is equipped with a first compensation slide, the first compensation lens mount is equipped with the first compensation slide, the third lens is equipped with the first compensation lens mount and locked with the first compensation pressure ring. The rear section of the main mirror mount is equipped with a second compensation slide, the second compensation lens mount is equipped with the second compensation slide, the fourth lens is equipped with the second compensation lens mount and locked with the second compensation pressure ring. The rear end of the main mirror mount is connected to a flange mount, in which the fifth lens is mounted and locked with a first rear pressure ring; the flange mount is mounted in the focus mount, in which the focus lens mount is mounted, in which the sixth lens is mounted, which is compressed with a second rear pressure ring and then locked with a focus lens mount pressure ring. The main mirror mount and the flange mount are rigidly connected via four M3 hexagon socket screws;

[0033] The electric zoom mechanism includes a motor frame, a cam, a cam guide, a zoom slide, a zoom lens group, a first compensation slide, a third lens, a second compensation slide, a fourth lens, and a micro switch. The motor frame is provided with a motor, a motor gear, a potentiometer, and a potentiometer gear. The motor gear is rigidly connected to the motor, and the potentiometer gear is rigidly connected to the potentiometer. The motor frame is fixed to the main lens barrel via two M3 hexagon socket screws. The motor gear is precisely meshed with the cam, and a cam guide is installed in the cam groove. The cam guide is rigidly connected to the zoom slide, the first compensation slide, and the second compensation slide. The zoom lens group is installed in the zoom slide, the third lens is installed in the first compensation slide, and the fourth lens is installed in the second compensation slide. The potentiometer gear is precisely meshed with the cam.

[0034] The electric focusing mechanism includes a motor frame, a transition wheel, a focusing ring, a focusing guide, a focusing seat, a focusing lens seat, a focusing lens, and a microswitch. The motor frame is equipped with a motor, a motor gear, a potentiometer, and a potentiometer gear. The motor gear is rigidly connected to the motor, and the potentiometer gear is rigidly connected to the potentiometer. The motor frame is secured to the main lens seat via two M3 hexagon socket head cap screws. The motor gear precisely meshes with the transition wheel, which in turn precisely meshes with the focusing ring. The focusing guide is mounted in the groove of the focusing ring and rigidly connected to the focusing seat. The focusing lens seat is mounted within the focusing seat, and the focusing lens seat is mounted within the focusing lens seat. The potentiometer gear precisely meshes with the motor gear.

[0035] An imaging method for a three-component mobile large-magnification infrared zoom lens: light from the object side passes through a first lens, a second lens, an aperture, a third lens, a fourth lens, a fifth lens, and a sixth lens in sequence to form an image on an imaging surface.

[0036] Unless otherwise stated, for any of the technical solutions disclosed in the present invention, if a numerical range is disclosed, the disclosed numerical range is a preferred numerical range. Any person skilled in the art should understand that the preferred numerical range is merely a numerical range that is representative or has a more obvious technical effect among many feasible numerical values. Due to the large number of numerical values, it is impossible to enumerate them exhaustively. Therefore, the present invention discloses some numerical values to illustrate the technical solutions of the present invention. Moreover, the numerical values listed above should not be construed as limiting the scope of protection of the present invention.

[0037] If words such as "first" and "second" are used in this document to limit components, those skilled in the art should know that the use of "first" and "second" is only for the convenience of description to distinguish between components. Unless otherwise stated, the above words have no special meaning.

[0038] If the present invention discloses or involves components or structural parts that are fixedly connected to each other, then, unless otherwise stated, the fixed connection can be understood as: a detachable fixed connection (for example, connection using bolts or screws), and can also be understood as: a non-detachable fixed connection (for example, riveting, welding). Of course, the mutual fixed connection can also be replaced by an integrated structure (for example, manufactured by integrated molding using a casting process) (except where it is obviously impossible to use an integrated molding process).

[0039] In addition, the orientations or positional relationships indicated by terms such as "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", and "outside" used in any of the technical solutions disclosed in the above invention are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing this patent, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on this patent. Unless otherwise stated, the terms used to indicate shapes used in any of the technical solutions disclosed in the above invention include shapes that are approximate, similar, or close to them.

[0040] Any component provided by the present invention may be assembled from multiple separate components, or may be a separate component manufactured by an integral molding process.

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention and not to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solution of the present invention. They should all be included in the scope of the technical solution for protection of the present invention.

Claims

1. A three-element mobile large zoom ratio infrared zoom lens, characterized in that: The lens is composed of a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens arranged in sequence from front to back along the incident light path, wherein the first lens is a positive lens, the second lens is a negative lens, the third lens is a positive lens, the fourth lens is a negative lens, the fifth lens is a negative lens, and the sixth lens is a positive lens; The focal length of the lens is f, and the focal lengths of the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens are f respectively. A 、f B 、f C 、f D 、f E1 、f E2 , the focal length at the telephoto position is f L , the focal length at the short focal length is f S , where f, f A 、f B 、f C 、f D 、f E1 、f E2 、f L 、f S The following relationship is satisfied: 0.23<|f A / f L |<0.5,0.03<|f B / f L |<0.05,0.02<|f C / f L |<0.06,0.045<|f D / f L |<0.085,0.06<|f E1 / f L |<0.12,0.01<|f E2 / f L |<0.035, where 3<|f A / f S |<5, 0.43<|f B / f S |<0.74,0.55<|f C / f S |<1.2,1.45<|f D / f S |<1.78,1.5<|f E1 / f S |<2.1,0.32<|f E2 / f S |<0.

58.

2. The zoom lens according to claim 1, wherein: The first lens and the third lens are made of silicon single crystal, and the second lens, the fourth lens, the fifth lens and the sixth lens are made of germanium single crystal.

3. The zoom lens according to claim 2, wherein: The air gap between the first lens and the second lens is 19.4mm-44mm; the air gap between the second lens and the third lens is 45.0mm-2.2mm; the air gap between the third lens and the fourth lens is 2.5mm-9.2mm; the air gap between the fourth lens and the fifth lens is 2.5mm-14.1mm; and the air gap between the fifth lens and the sixth lens is 11.0mm.

4. The zoom lens according to claim 3, wherein: The first lens satisfies the relationship: N d =3.42, V d =236; the second lens satisfies the relationship: N d =4.00, V d =107; the third lens satisfies the relationship: N d =3.42, V d =236; the fourth lens satisfies the relationship: N d =4.00, V d =107; the fifth lens satisfies the relationship: N d =4.00, V d =107; the sixth lens satisfies the relationship: N d =4.00, V d =107; where N d is the refractive index, V d is the Abbe constant.

5. The zoom lens according to claim 4, wherein: The operating wavelength range of the lens is 3.7-4.8 μm.

6. The zoom lens according to claim 5, wherein: The relative aperture of the lens is 1 / 4, and the lens is a medium-wave infrared lens with a 20-fold zoom ratio.

7. The zoom lens according to claim 6, wherein: The lens barrel structure also includes a main lens barrel, a front lens seat is installed in the front section of the main lens barrel, a first lens is installed in the front lens seat, a zoom slide, a first compensation slide, and a second compensation slide are sequentially arranged on the rear section of the lens barrel structure from front to rear, the second lens, the third lens, and the fourth lens are respectively installed in the zoom slide, the first compensation slide, and the second compensation slide, a flange seat is installed on the rear end of the main lens barrel, a fifth lens is installed in the front section of the flange seat, a focusing lens seat is installed in the rear section of the flange seat, and a sixth lens is installed in the focusing lens seat.

8. An imaging method using a three-component mobile large-zoom infrared zoom lens, using the zoom lens of claim 7, characterized in that: The light passes through the first lens, the second lens, the aperture, the third lens, the fourth lens, the fifth lens, and the sixth lens from the object side to form an image on the imaging surface.

Images