A Compact Mid-Wave Infrared Continuous Zoom Lens and Its Imaging Method

Abstract

The present invention provides a compact medium-wave infrared continuous zoom lens and an imaging method thereof: the lens comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens, which are sequentially arranged along the direction of incident light. The lens also comprises a barrel structure, wherein the barrel structure comprises a main barrel and a rear barrel, wherein the rear barrel is fixed to the rear end of the main barrel, the first lens is mounted in the front end of the main barrel, a magnification component and a compensation component are movably connected in sequence in the main barrel along the direction of the light path, a focusing component is movably connected in the front end of the rear barrel, and the fifth lens, the sixth lens, and the seventh lens are sequentially mounted in the rear barrel. The present invention has a reasonable design, uses only seven lenses, and has the functions of continuous zoom, focusing, and scene virtual imaging. At the same time, the mechanical structure adopts a slide structure design, which can ensure the stability of the image during the zooming process. Moreover, the present invention has the advantages of small size, light weight, and compact structure, and has good application prospects in optoelectronic turrets or small pod equipment.

Description

Technical Field

[0001] The invention relates to a compact medium-wave infrared continuous zoom lens and an imaging method thereof. Background Art

[0002] In recent years, infrared continuous zoom systems have been widely used in various fields such as border defense, coastal defense, and optoelectronic detection. The requirements for their weight and size are becoming increasingly higher. In practical applications, the target image must always remain clear. The current existing infrared continuous zoom systems have a relatively complex structure, cannot guarantee the stability of the image during the zoom process, and are relatively large in size. Summary of the Invention

[0003] In light of this, the present invention aims to overcome the shortcomings of the aforementioned prior art by providing a compact medium-wave infrared continuous zoom lens and imaging method. Using only seven lenses, the system offers continuous zoom, focus adjustment, and scene defocusing capabilities. Furthermore, the slide-type mechanical design ensures image stability during zooming. Furthermore, its small size, light weight, and compact structure make it a promising candidate for application in optoelectronic turrets or small pods.

[0004] The present invention is implemented by the following scheme: a compact medium-wave infrared continuous zoom lens: the lens is composed of a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens arranged in sequence along the direction of incident light, the first lens is a meniscus positive lens, the second lens is a biconcave negative lens, the third lens is a biconvex positive lens, the fourth lens is a meniscus negative lens, the fifth lens is a meniscus positive lens, the sixth lens is a biconcave negative lens, and the seventh lens is a meniscus positive lens.

[0005] Furthermore, the short-focus total focal length of the lens is f, and the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens are f1, f2, f3, f4, f5, f6, and f7, respectively, wherein f1, f2, f3, f4, f5, f6, and f7 satisfy the following ratio with f: 30 <f1 / f<35;-10<f2 / f<-5;5<f3 / f<10;-30<f4 / f<-20;0<f5 / f<5;-5<f6 / f<0;0<f7 / f<5。

[0006] Furthermore, the first lens satisfies the relationship: 3.1≤N d ≤4.0, 228≤V d ≤245; the second lens satisfies the relationship: 3.7≤N d ≤4.5, 98≤V d ≤110; the third lens satisfies the relationship: 3.1≤N d ≤4.03.1≤Nd ≤4.0, 228≤V d ≤245; the fourth lens satisfies the relationship: 3.7≤N d ≤4.5, 98≤V d ≤110; the fifth lens satisfies the relationship: 3.1≤N d ≤4.0, 228≤V d ≤245; the sixth lens satisfies the relationship: 3.7≤N d ≤4.5, 98≤V d ≤110; the seventh lens satisfies the relationship: 3.1≤N d ≤4.0, 228≤V d ≤245; where N d is the refractive index, V d is the Abbe constant.

[0007] Furthermore, the air gap between the first lens and the second lens is 10.35 mm to 15.46 mm; the air gap between the second lens and the third lens is 11.67 mm to 1.29 mm; the air gap between the third lens and the fourth lens is 1.97 mm to 6.93 mm; the air gap between the fourth lens and the fifth lens is 9.45 mm; the air gap between the fifth lens and the sixth lens is 1.55 mm; and the air gap between the sixth lens and the seventh lens is 0.08 mm.

[0008] Furthermore, the image side mirror surface of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens are all aspherical lenses, and the aspherical curve equation is expressed as:

[0009]

[0010] Z represents the position in the direction of the optical axis, r represents the height in the vertical direction relative to the optical axis, c represents the radius of curvature, k represents the cone coefficient, α4, α6, α8, α 10 ...represents the aspheric coefficients.

[0011] Furthermore, the F# of the lens is less than 4.

[0012] Furthermore, the H / f of the lens is 0.06 to 0.2.

[0013] Furthermore, the lens also includes a barrel structure, the barrel structure has a main barrel and a rear barrel, the rear barrel is fixed to the rear end of the main barrel, the first lens is installed in the front end of the main barrel, the main barrel is movably connected with a zoom component and a compensation component in sequence along the optical path, the front end of the rear barrel is movably connected with a focusing component, the fifth lens, the sixth lens, and the seventh lens are installed in the rear barrel in sequence; the zoom component includes a zoom slide, the second lens is installed in the zoom slide, the zoom slide is slidably connected to the main barrel, the compensation component includes a compensation slide, the third lens is installed in the compensation slide, the compensation slide is slidably connected to the main barrel, the zoom guide pin assembly is installed on the zoom slide and the compensation slide, the outside of the main barrel is sleeved with a zoom cam corresponding to the zoom component and the compensation component, the The main lens barrel is provided with a zoom guide straight groove along the length direction of the main lens barrel corresponding to the zoom guide pin assembly outside the main lens barrel, and the zoom cam is provided with a zoom curve groove and a compensation curve groove respectively on the zoom guide pin assembly on the magnification slide and the compensation slide; a zoom driven gear is installed on the outer periphery of the zoom cam, and a zoom motor for driving the zoom driven gear to rotate is installed outside the main lens barrel, and a zoom driving gear meshing with the zoom driven gear is installed on the output shaft of the zoom motor. Zoom limit pins are provided on the outer periphery of the zoom cam at the extreme positions corresponding to the magnification curve groove and the compensation curve groove, and a zoom limit switch is installed on the main lens barrel corresponding to the limit pin, and the contact point of the zoom limit switch is horizontally placed outside the magnification curve groove or the compensation curve groove corresponding to the zoom limit pin, and a zoom potentiometer assembly is installed on the outside of the main lens barrel beside the zoom motor.

[0014] Furthermore, the focusing assembly includes a focusing slide, the fourth lens is installed in the focusing slide, the focusing slide is slidably connected to the rear barrel, and a focusing guide pin assembly is installed on each of the focusing slides. A focusing cam is sleeved on the focusing assembly outside the rear barrel, and a focusing guide straight groove is provided along the length direction of the rear barrel corresponding to the focusing guide pin assembly outside the rear barrel, and a focusing magnification curve groove is provided on the zoom guide pin assembly on the focusing slide corresponding to the focusing cam; a focusing driven gear is installed on the outer periphery of the focusing cam. A focusing motor for driving the focusing driven gear to rotate is installed outside the rear lens barrel, and a focusing active gear engaged with the focusing driven gear is installed on the output shaft of the focusing motor. Focusing limit pins are provided at the extreme positions of the focusing curve groove on the outer periphery of the focusing cam, and a focusing limit switch is installed on the rear lens barrel corresponding to the focusing limit pin. The contact point of the focusing limit switch corresponds to the focusing limit pin and is horizontally placed outside the focusing curve groove. A focusing potentiometer assembly is installed outside the rear lens barrel next to the focusing motor.

[0015] An imaging method for a compact medium-wave infrared continuous zoom lens; when light is incident, the light path sequentially enters a first lens, a second lens, a third lens, an aperture, a fourth lens, a fifth lens, a sixth lens, and a seventh lens, and finally forms an image on an image plane.

[0016] Compared with the existing technology, the present invention has the following beneficial effects: reasonable design, only 7 lenses are used, and it has the functions of continuous zooming, focusing and scene virtual imaging; at the same time, the mechanical structure adopts a slide structure design, which can ensure the stability of the image during the zooming process, and it has the advantages of small size, light weight and compact structure, and has good application prospects in optoelectronic turrets or small pod equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the lens structure according to an embodiment of the present invention;

[0018] Figure 2 Schematic diagram of the cross-sectional structure of an embodiment of the present invention;

[0019] Figure 3 Schematic diagram of the structure of an embodiment of the present invention;

[0020] Figure 4 This is an MTF diagram of an embodiment of the present invention at short focus;

[0021] Figure 5 This is an MTF diagram at telephoto angle according to an embodiment of the present invention;

[0022] Figure 6 is a short-focus distortion diagram of an embodiment of the present invention;

[0023] Figure 7 is a telephoto distortion diagram of an embodiment of the present invention;

[0024] Figure 8 Schematic diagram of the structure of the zoom slide and the compensation slide according to an embodiment of the present invention. DETAILED DESCRIPTION

[0025] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0026] 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.

[0027] 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.

[0028] like Figure 1-3 As shown, a compact medium-wave infrared continuous zoom lens is composed of a first lens A, a second lens B, a third lens C, a fourth lens D, a fifth lens E1, a sixth lens E2, and a seventh lens E3, which are arranged in sequence along the incident direction of light. The first lens is a positive meniscus lens, the second lens is a biconcave negative lens, the third lens is a biconvex positive lens, the fourth lens is a negative meniscus lens, the fifth lens is a positive meniscus lens, the sixth lens is a biconcave negative lens, and the seventh lens is a positive meniscus lens.

[0029] In this embodiment, the short-focus total focal length of the lens is f, and the first lens, second lens, third lens, fourth lens, fifth lens, sixth lens, and seventh lens are f1, f2, f3, f4, f5, f6, and f7, respectively, where f1, f2, f3, f4, f5, f6, and f7 satisfy the following ratio with f: 30 <f1 / f<35;-10<f2 / f<-5;5<f3 / f<10;-30<f4 / f<-20;0<f5 / f<5;-5<f6 / f<0;0<f7 / f<5。

[0030] In this embodiment, the first lens satisfies the relationship: 3.1≤N d ≤4.0, 228≤V d ≤245; the second lens satisfies the relationship: 3.7≤N d ≤4.5, 98≤V d ≤110; the third lens satisfies the relationship: 3.1≤N d ≤4.03.1≤N d ≤4.0, 228≤V d ≤245; the fourth lens satisfies the relationship: 3.7≤N d ≤4.5, 98≤V d ≤110; the fifth lens satisfies the relationship: 3.1≤N d ≤4.0, 228≤V d ≤245; the sixth lens satisfies the relationship: 3.7≤N d ≤4.5, 98≤V d ≤110; the seventh lens satisfies the relationship: 3.1≤N d ≤4.0, 228≤V d≤245; where N d is the refractive index, V d is the Abbe constant.

[0031] In this embodiment, the air gap between the first lens and the second lens is 10.35 mm to 15.46 mm; the air gap between the second lens and the third lens is 11.67 mm to 1.29 mm; the air gap between the third lens and the fourth lens is 1.97 mm to 6.93 mm; the air gap between the fourth lens and the fifth lens is 9.45 mm; the air gap between the fifth lens and the sixth lens is 1.55 mm; and the air gap between the sixth lens and the seventh lens is 0.08 mm.

[0032] In this embodiment, the lens utilizes a secondary imaging structure and utilizes conventional infrared materials. The imaging lens has a small aperture and is easy to manufacture. During the design optimization process, the optical power of each lens element is rationally distributed, and even-order aspheric surfaces are used to balance system aberrations, resulting in a sufficiently compact overall optical system. Adjustments to curvature and thickness reduce the sensitivity of individual optical components, making the lens easier to manufacture and assemble.

[0033] In this embodiment, the lens achieves the following optical indicators:

[0034] 1. Working band: 3um~5um;

[0035] 2. Focal length range: short focus <50mm, long focus >200mm;

[0036] 3. F#: less than 4;

[0037] 4. Optical transfer function: When the transfer function spatial frequency is 25p / mm, the center MTF is ≥0.4 at long focus and short focus, and it still has good imaging quality at the maximum field of view, and the edge field of view MTF is ≥0.2.

[0038] 5. The total optical length is less than 90mm;

[0039] 6. H / f: 0.06~0.2.

[0040] The specific physical parameters of each lens meet the data requirements shown in Table 1:

[0041] Table 1 Optical component parameters

[0042]

[0043] In this embodiment, the image side mirror surface of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens are all aspherical lenses.

[0044] The expression of aspherical mirror is:

[0045]

[0046] Z represents the position in the direction of the optical axis, r represents the height in the vertical direction relative to the optical axis, c represents the radius of curvature, k represents the cone coefficient, α4, α6, α8, α 10 ... represents the aspheric coefficient. In aspheric data, En represents "×10 -n ", for example, 1.719E-05 represents 1.719×10 -5 .

[0047] Table 2 Aspheric surface related data

[0048] <![CDATA[α4]]> <![CDATA[α6]]> <![CDATA[α8]]> <![CDATA[α 10 ]]> Aspheric S2 9.113E-07 -2.866E-010 5.10127E-14 3.3929E-17 Aspheric S3 5.462E-06 -2.433E-07 4.0294E-10 1.0437E-12 Aspheric S4 5.548E-07 -6.295E-08 -4.247E-10 3.2795E-12 Aspheric S5 -1.286E-05 4.9032E-09 -1.198E-10 8.5306E-13 Aspheric S6 1.9589E-05 -5.737E-08 2.4617E-11 6.6002E-13 Aspheric S7 -3.673E-05 -9.677E-07 -2.893E-09 -4.629E-11 Aspherical S8 -2.431E-04 -1.927E-05 1.9276E-07 -6.484E-10 Aspherical S9 -1.967E-04 1.6164E-05 4.9089E-07 -3.270E-08 Aspherical S10 1.5107E-03 -4.371E-05 2.2908E-06 -4.019E-08 Aspheric S11 7.0362E-03 -6.794E-04 4.4152E-05 -8.952E-07 Aspheric S12 4.5083E-04 -1.769E-04 1.1384E-05 -2.379E-07 Aspheric S13 -1.656E-03 6.1853E-05 3.4839E-07 -2.968E-08 Aspheric S14 9.2713E-04 -2.985E-05 1.6022E-06 -4.085E-09

[0049] In this embodiment, the lens also includes a lens barrel structure, which includes a main lens barrel 101 and a rear lens barrel 201. The rear lens barrel is fixed to the rear end of the main lens barrel, and the first lens is installed in the front end of the main lens barrel. The main lens barrel is movably connected with a magnification component 102 and a compensation component 103 along the direction of the optical path. The magnification component and the compensation component together constitute a zoom component. The front end of the rear lens barrel is movably connected with a focusing component. The fifth lens, the sixth lens, and the seventh lens are installed in the rear lens barrel in sequence.

[0050] In this embodiment, the magnification component includes a magnification slide 104, the second lens is installed in the magnification slide, the magnification slide is slidably connected to the main lens barrel, the compensation component includes a compensation slide 105, the third lens is installed in the compensation slide, the compensation slide is slidably connected to the main lens barrel, the magnification slide and the compensation slide are both installed with a zoom guide pin assembly 106, the main lens barrel corresponds to the magnification component and the compensation component is sleeved with a zoom cam 107, the main lens barrel corresponds to the zoom guide pin assembly outside the main lens barrel is provided with a zoom guide straight groove 108 opened along the length direction of the main lens barrel, the zoom cam corresponds to the magnification slide, the zoom guide pin assembly on the compensation slide is respectively provided with a magnification curve groove 109 and a compensation curve groove, the zoom cam is formed with the main lens barrel through a steel ball. Rolling connection, and a shoulder is provided on the outer periphery of the main lens barrel. The zoom cam is clamped on the shoulder by the rear side of the main lens barrel, and then locked by the zoom cam pressure ring. The zoom guide pin assembly, the zoom guide straight groove and the zoom curve groove are coordinated, and the zoom guide pin assembly, the zoom guide straight groove and the compensation curve groove are coordinated to realize the forward and backward sliding of the zoom slide and the compensation slide. When the zoom motor rotor makes positive and negative rotational motion, it drives the zoom cam to rotate accordingly, and drives the zoom assembly and the compensation assembly to move according to the optical design requirements through the zoom curve groove, the compensation curve groove and the zoom guide pin assembly. The two zoom guide straight grooves on the main lens barrel play the role of limiting the zoom guide pin assembly, and convert the rotational motion of the zoom assembly and the compensation assembly into linear motion, thereby realizing the zoom function of the system lens.

[0051] In this embodiment, the focusing assembly includes a focusing slide 202, the fourth lens is installed in the focusing slide, the focusing slide is slid into the rear barrel, and a focusing guide pin assembly 203 is installed on the focusing slide. The focusing assembly outside the rear barrel is sleeved with a focusing cam 204, and the corresponding focusing guide pin assembly outside the rear barrel is provided with a focusing guide straight groove 205 opened along the length direction of the rear barrel. The zoom guide pin assembly on the focusing slide corresponding to the focusing cam is respectively provided with a focusing magnification curve groove 206. The specific sliding method is similar to that of the zoom assembly and the compensation assembly, so it will not be repeated.

[0052] In this embodiment, a zoom driven gear 111 is installed on the periphery of the zoom cam, a zoom motor 112 for driving the zoom driven gear to rotate is installed on the outside of the main barrel, a zoom driving gear 113 engaged with the zoom driven gear is installed on the output shaft of the zoom motor, and zoom limit pins 114 are provided on the periphery of the zoom cam corresponding to the limit positions of the magnification curve groove and the compensation curve groove, and a zoom limit switch 115 is installed on the main barrel corresponding to the limit pin, and the contact point of the zoom limit switch corresponds to the zoom limit pin horizontally placed In addition to the zoom curve groove or the compensation curve groove, it plays a role in limiting and protecting the system during the zoom process. An existing zoom potentiometer assembly 116 is installed outside the main lens barrel next to the zoom motor. The potentiometer gear on the zoom potentiometer assembly is connected to the gear outside the zoom cam. When the zoom cam rotates relatively, the resistance value of the potentiometer changes. The change value of the potentiometer can be calculated through an appropriate sampling circuit and transmitted to the control center, thereby realizing the display of the zoom value. Conversely, the corresponding resistance value command is given by the control center to realize real-time control of the focal length.

[0053] In this embodiment, a focusing driven gear 207 is installed on the outer periphery of the focusing cam, a focusing motor 208 for driving the focusing driven gear to rotate is installed outside the rear barrel, a focusing active gear 209 engaged with the focusing driven gear is installed on the output shaft of the focusing motor, and focusing limit pins 210 are provided at the extreme positions of the focusing curve groove corresponding to the outer periphery of the focusing cam, and a focusing limit switch 211 is installed on the rear barrel corresponding to the focusing limit pin. The contact point of the focusing limit switch corresponds to the focusing limit pin and is horizontally placed outside the focusing curve groove. A focusing potentiometer assembly 212 is installed outside the rear barrel next to the focusing motor. The specific working principle is similar to that of the magnification component and the compensation component, so it will not be repeated.

[0054] Compared with other lenses, this lens has the following advantages:

[0055] 1) The system of the present invention adopts a secondary imaging optical path design, with the aperture positioned on the detector cold aperture, ensuring 100% cold aperture efficiency. Secondary imaging is more conducive to compressing the aperture of each lens in the system, making the system lightweight.

[0056] 2) The system of the present invention adopts silicon germanium as a material, which is more conducive to correcting the chromatic aberration of the system and ensuring that the image quality remains good during the zoom process.

[0057] 3) The optical system of the present invention has a small number of lenses and a relatively short total length, and can be directly connected to a detector for use.

[0058] 4) The present invention adopts a straight-tube structure. Compared with the folding lens structure design, the present invention has the advantages of fewer lenses, easy installation and adjustment, and compact structure, which can realize the miniaturization and lightweight design of the system.

[0059] 5) The present invention adopts a cam structure design, which has a short optical stroke and a slide structure for zooming, which can ensure the advantages of a smooth zoom trajectory and a stable optical axis.

[0060] 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.

[0061] 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.

[0062] 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).

[0063] 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.

[0064] 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.

[0065] 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 compact medium-wave infrared continuous zoom lens, characterized by: The lens is composed of a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens, which are arranged in sequence along the incident direction of light, wherein the first lens is a positive meniscus lens with a convex surface facing the object plane, the second lens is a double concave negative lens, the third lens is a double convex positive lens, the fourth lens is a negative meniscus lens with a convex surface facing the image plane, the fifth lens is a positive meniscus lens with a convex surface facing the image plane, the sixth lens is a double concave negative lens, and the seventh lens is a positive meniscus lens with a convex surface facing the image plane; The short-focus total focal length of the lens is f, and the first lens, second lens, third lens, fourth lens, fifth lens, sixth lens, and seventh lens are f1, f2, f3, f4, f5, f6, and f7, respectively. Among them, f1, f2, f3, f4, f5, f6, and f7 satisfy the following ratio with f: 30 <f1 / f<35;-10<f2 / f<-5;5<f3 / f<10;-30<f4 / f<-20;0<f5 / f<5;-5<f6 / f<0;0<f7 / f<5。 2. The compact medium-wave infrared continuous zoom lens according to claim 1, characterized in that: The first lens satisfies the relationship: 3.1≤N d ≤4.0, 228≤V d ≤245; the second lens satisfies the relationship: 3.7≤N d ≤4.5, 98≤V d ≤110; the third lens satisfies the relationship: 3.1≤N d ≤4.03.1≤N d ≤4.0, 228≤V d ≤245; the fourth lens satisfies the relationship: 3.7≤N d ≤4.5, 98≤V d ≤110; the fifth lens satisfies the relationship: 3.1≤N d ≤4.0, 228≤V d ≤245; the sixth lens satisfies the relationship: 3.7≤N d ≤4.5, 98≤V d ≤110; the seventh lens satisfies the relationship: 3.1≤N d ≤4.0, 228≤V d ≤245; where N d is the refractive index, V d is the Abbe constant.

3. The compact medium-wave infrared continuous zoom lens according to claim 1, characterized in that: The air gap between the first lens and the second lens is 10.35mm to 15.46mm; the air gap between the second lens and the third lens is 11.67mm to 1.29mm; the air gap between the third lens and the fourth lens is 1.97mm to 6.93mm; the air gap between the fourth lens and the fifth lens is 9.45mm; the air gap between the fifth lens and the sixth lens is 1.55mm; and the air gap between the sixth lens and the seventh lens is 0.08mm.

4. The compact medium-wave infrared continuous zoom lens according to claim 1, characterized in that: The image side mirror surface of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens are all aspherical lenses, and the aspherical curve equation is expressed as: Z represents the position in the direction of the optical axis, r represents the height in the vertical direction relative to the optical axis, c represents the radius of curvature, k represents the cone coefficient, α4, α6, α8, α 10 ...represents the aspheric coefficients.

5. The compact medium-wave infrared continuous zoom lens according to claim 1, characterized in that: The F# of the lens is less than 4.

6. The compact medium-wave infrared continuous zoom lens according to claim 1, characterized in that: The H / f of the lens is 0.06 to 0.

2.

7. The compact medium-wave infrared continuous zoom lens according to claim 1, characterized in that: The lens also includes a barrel structure, the barrel structure has a main barrel and a rear barrel, the rear barrel is fixed to the rear end of the main barrel, the first lens is installed in the front end of the main barrel, the main barrel is movably connected with a zoom component and a compensation component in sequence along the light path direction, the front end of the rear barrel is movably connected with a focusing component, the fifth lens, the sixth lens, and the seventh lens are installed in the rear barrel in sequence; the zoom component includes a zoom slide, the second lens is installed in the zoom slide, the zoom slide is slidably connected to the main barrel, the compensation component includes a compensation slide, the third lens is installed in the compensation slide, the compensation slide is slidably connected to the main barrel, the zoom guide pin assembly is installed on the zoom slide and the compensation slide, the outside of the main barrel is sleeved with a zoom cam corresponding to the zoom component and the compensation component, the main barrel The zoom guide pin assembly outside the barrel is provided with a zoom guide straight groove opened along the length direction of the main lens barrel, and the zoom cam is provided with a zoom curve groove and a compensation curve groove on the zoom guide pin assembly corresponding to the magnification slide and the compensation slide respectively; a zoom driven gear is installed on the outer periphery of the zoom cam, and a zoom motor for driving the zoom driven gear to rotate is installed outside the main lens barrel, and a zoom driving gear engaged with the zoom driven gear is installed on the output shaft of the zoom motor. Zoom limit pins are provided at the extreme positions of the zoom curve groove and the compensation curve groove on the outer periphery of the zoom cam, and a zoom limit switch is installed on the main lens barrel corresponding to the limit pin. The contact point of the zoom limit switch is horizontally placed outside the magnification curve groove or the compensation curve groove corresponding to the zoom limit pin, and a zoom potentiometer assembly is installed outside the main lens barrel beside the zoom motor.

8. The compact medium-wave infrared continuous zoom lens according to claim 7, characterized in that: The focusing assembly includes a focusing slide, the fourth lens is installed in the focusing slide, the focusing slide is slidably connected to the rear lens barrel, and a focusing guide pin assembly is installed on each of the focusing slides. A focusing cam is sleeved on the focusing assembly outside the rear lens barrel. The corresponding focusing guide pin assembly outside the rear lens barrel is provided with a focusing guide straight groove opened along the length direction of the rear lens barrel. The focusing cam is provided with a focusing magnification curve groove on the zoom guide pin assembly on the focusing slide; a focusing driven gear is installed on the outer periphery of the focusing cam. A focusing motor for driving the focusing driven gear to rotate is installed outside the rear lens barrel, and a focusing active gear meshing with the focusing driven gear is installed on the output shaft of the focusing motor. Focusing limit pins are provided at the extreme positions of the focusing curve groove on the outer periphery of the focusing cam, and a focusing limit switch is installed on the rear lens barrel corresponding to the focusing limit pin. The contact point of the focusing limit switch corresponds to the focusing limit pin and is horizontally placed outside the focusing curve groove. A focusing potentiometer assembly is installed outside the rear lens barrel next to the focusing motor.

9. An imaging method using a compact medium-wave infrared continuous zoom lens, using the compact medium-wave infrared continuous zoom lens according to claim 1, characterized in that: When light is incident, the light path enters the first lens, second lens, third lens, aperture, fourth lens, fifth lens, sixth lens, and seventh lens in sequence, and finally forms an image on the image plane.

Images