Infrared front lens

Abstract

The utility model discloses an infrared front lens, which comprises a lens body group, a rear lens group and a connecting bracket group, the rear lens group is connected to the rear end of the lens body group, and the two ends of the connecting support group are detachably connected with the infrared front lens and an external white light sighting telescope respectively. The lens body group comprises a lens body, an infrared objective lens group and an infrared movement group which are sequentially arranged in the lens body, and a control panel, a power supply group, a focusing group and a wireless communication group which are arranged on the side surface of the lens body; an eyepiece group and a display screen are arranged in the rear lens group. The infrared front lens can be assembled with a white light sighting telescope to achieve infrared sighting, and is comprehensive in function and suitable for complex scenes.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of optical sighting telescope, specifically relates to an infrared front lens. BACKGROUND

[0002] At present, in order to expand the day and night use demand of white light sighting telescope, improve the all-weather operation effectiveness of weapon system, infrared sighting telescope is often added to it to realize functional connection, and there is great market demand.But the current infrared front lens is generally simple in function, and it is insufficient to meet the actual demand. CONTENT OF UTILITY MODEL

[0003] The utility model aims at providing an infrared front lens, which has the functions of focusing, diopter adjustment and wireless communication, can adapt to complex environment and meet various use requirements.

[0004] To solve the above technical problems, the utility model provides an infrared front lens, which comprises a mirror body group, a rear lens group and a connecting bracket group; the rear lens group is connected to the rear end of the mirror body group; and the two ends of the connecting bracket group are respectively detachably connected with the infrared front lens and an external white light sighting telescope.

[0005] The mirror body group comprises a mirror body, an infrared objective lens group, an infrared movement core group arranged in the mirror body in sequence, and a control panel, a power supply group, a focusing group and a wireless communication group arranged on the side surface of the mirror body.

[0006] The rear lens group is provided with an ocular lens group and a display screen.

[0007] According to the above scheme, the infrared movement core group comprises an infrared movement core and a movement core seat, the infrared movement core is fixed on the movement core seat, and the movement core seat is fixed on the mirror body.

[0008] According to the above scheme, the control panel comprises a mirror body cover plate, and a key group, an encoder group and a wireless communication group fixed on the mirror body cover plate.

[0009] The mirror body cover plate is fixed on the mirror body.

[0010] The key group comprises a key circuit board and a first key cover, the key circuit board is fixed on the mirror body cover plate, and the wireless communication group comprises a wireless communication cover plate connected to the mirror body cover plate.

[0011] The encoder group comprises an encoder and an encoder hand wheel group, the encoder is fixed on the mirror body cover plate, and the control end of the encoder is connected with the encoder hand wheel group.

[0012] According to the above scheme, the power supply group comprises a battery, a battery compartment, a battery cover group and an electrode group, the battery compartment is located on the side surface of the mirror body, the electrode group is arranged at the bottom of the battery compartment, the battery is arranged in the battery compartment, the battery cover group is detachably connected with the battery compartment, and the battery cover group and the electrode group are respectively electrically connected with the negative electrode and the positive electrode of the battery.

[0013] According to the above scheme, the focusing group comprises an inner distance adjusting wheel, a focusing hand wheel and a focusing screw, the inner distance adjusting wheel is rotatably connected with the mirror body, the focusing hand wheel is fixed outside the inner distance adjusting wheel, a curved groove is arranged on the inner side surface of the inner distance adjusting wheel, a straight groove is arranged on the mirror body, one end of the focusing screw is located in the curved groove, and the other end of the focusing screw passes through the straight groove and is threadedly connected with the infrared objective lens group.

[0014] According to the above scheme, the connecting support group comprises a connecting seat, and open rings are arranged at two ends of the connecting seat and are respectively connected with the ocular lens group and an opening ring of the external white light sighting telescope.

[0015] According to the above scheme, the battery compartment is at a certain oblique angle relative to the axial direction of the mirror body.

[0016] According to the above scheme, a plurality of interfaces with certain hole distances are arranged on the mirror body, and the interfaces of the mirror body are fixed with standard picatinny rails.

[0017] According to the above scheme, the ocular lens optical system in the ocular lens group comprises, from the human eye to the display screen, a first meniscus lens, a double-convex lens, a second meniscus lens, a third meniscus lens, a fourth meniscus lens and a fifth meniscus lens, wherein the first meniscus lens and the double-convex lens are tightly bonded as a cemented lens.

[0018] According to the above scheme, the focal length fa of the cemented lens satisfies 58.71mm<fa<64.89mm.

[0019] The focal length fb of the second meniscus lens satisfies 32.34mm<fb<35.75mm.

[0020] The focal length fc of the third meniscus lens satisfies 17.80mm<fc<19.67mm.

[0021] The focal length fd of the fourth meniscus lens satisfies 40.24mm<fd<44.48mm.

[0022] The focal length fe of the fifth meniscus lens satisfies 29.36mm<fe<32.45mm.

[0023] The air gap between the cemented lens and the second meniscus lens is 0.3±0.03mm, the air gap between the second meniscus lens and the third meniscus lens is 2.73±0.03mm, the air gap between the third meniscus lens and the fourth meniscus lens is 3.54±0.03mm, and the air gap between the fourth meniscus lens and the fifth meniscus lens is 0.3±0.03mm.

[0024] Advantages

[0025] The utility model discloses a connecting support group can realize the assembly of infrared front mirror and white light collimating sight, make white light collimating sight possess infrared collimating function, through the setting control panel adjustment collimating parameter, to adapt to actual collimating demand, through the setting wireless communication group makes infrared front mirror can pass through wireless transmission to display terminal with video signal, has improved use efficiency and convenience. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 It is the infrared front mirror side view of an embodiment of the utility model;

[0027] Figure 2 It is Figure 1 A-A section view of;

[0028] Figure 3 It is the eyepiece group optical system structure diagram of an embodiment of the utility model;

[0029] Figure 4 It is the mirror body group explosion schematic drawing of an embodiment of the utility model;

[0030] Figure 5 It is the key group explosion schematic drawing of an embodiment of the utility model;

[0031] Figure 6 It is the focusing group section of an embodiment of the utility model;

[0032] Figure 7 It is the encoder group explosion schematic drawing of an embodiment of the utility model;

[0033] Figure 8 It is the battery cover group section of an embodiment of the utility model;

[0034] Figure 9 It is the electrode group explosion schematic drawing of an embodiment of the utility model;

[0035] Figure 10 It is the connecting support group of an embodiment of the utility model;

[0036] Figure 11 It is the curve slot schematic drawing of the inner distance regulating wheel of an embodiment of the utility model;

[0037] Figure 12 It is the point list diagram of the eyepiece group optical system of an embodiment of the utility model;

[0038] Figure 13 It is the field curvature distortion diagram of the eyepiece group optical system of an embodiment of the utility model.

[0039] In the figure: 1-infrared objective group, 2-mirror group, 3-rear mirror group, 4-control panel, 5-eyepiece group, 6-focusing group, 7-encoder group, 8-battery cover group, 9-electrode group, 10-connection support group;

[0040] 201-mirror, 202-movement base, 203-focusing washer, 204-mirror screw sleeve, 205-wire slot plate, 206-standard picatinny rail, 207-TYPE-C washer, 208-sealing washer, 209-steel wire screw sleeve, 210-TYPE-C interface, 211-infrared movement, 212-first screw, 213-second screw, 214-negative plate, 215-third screw, 216-fourth screw, 217-fifth screw, 218-sixth screw, 219-seventh screw;

[0041] 401-mirror cover plate, 402-first button cover, 403-WIFI cover, 404-first button washer, 405-eighth screw, 406-button circuit board;

[0042] 50101-first meniscus lens, 50102-biconvex lens, 502-second meniscus lens, 503-third meniscus lens, 504-fourth meniscus lens, 505-fifth meniscus lens;

[0043] 601-focusing hand wheel, 602-inner distance wheel, 603-focusing pressure ring, 604-focusing screw, 605-focusing label, 606-ninth screw, 607-first sealing ring, 608-second sealing ring, 609-focusing spring;

[0044] 701-encoder hand wheel, 702-second button cover, 703-second button washer, 704-encoder button pressure ring, 705-encoder second pressure ring, 706-third sealing ring, 707-encoder first pressure ring, 708-tenth screw, 709-encoder;

[0045] 801-battery cover, 802-battery cover screw sleeve, 803-electrode washer, 804-electrode spring, 805-fourth sealing ring;

[0046] 901-electrode sleeve ring, 902-electrode pressure ring, 903-positive plate, 904-electrode pad seat;

[0047] 1001-connection seat, 1002-locking handle, 1003-locking screw, 1004-locking nut, 1005-stop nut, 1006-cylindrical pin, 1007-washer, 1008-wavy washer, 1009-non-slip cloth. DETAILED DESCRIPTION

[0048] To make the purposes, technical solutions, and advantages of the embodiments of the present disclosure clearer, the technical solutions of the embodiments of the present disclosure will be described clearly and completely below with reference to the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are some but not all of the embodiments of the present disclosure. Based on the described embodiments of the present disclosure, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of protection of the present disclosure.

[0049] The embodiment provides an infrared front lens, comprising: a lens body group 2, a rear lens group 3, and a connecting bracket group 10; the rear lens group 3 is connected to the rear end of the lens body group 2, and the two ends of the connecting bracket group 10 are respectively detachably connected with the infrared front lens and an external white light sighting scope.

[0050] The lens body 201 group 2 comprises a lens body 201, and an infrared objective lens group 1, an infrared movement core 211 group arranged in the lens body 201 in sequence, and a control panel 4, a power supply group, a focusing group 6, and a wireless communication group arranged on the side surface of the lens body 201.

[0051] The rear lens group 3 is provided with an ocular group 5 and a display screen.

[0052] Further, the infrared movement core 211 group comprises an infrared movement core 211 and a movement core seat 202, the infrared movement core 211 is fixed on the movement core seat 202, and the movement core seat 202 is fixed on the lens body 201.

[0053] Further, the infrared movement core 211 seat 202 is fixed on the movement core seat 202 through a fourth screw 216, the movement core seat 202 is fixed on the lens body 201 through a fifth screw 217, and a plurality of stacked focusing washers 203 are arranged between the movement core seat 202 and the lens body 201, the number of the focusing washers 203 is determined by the focusing effect of the infrared front lens during assembly.

[0054] Further, the through hole, through which the fifth screw 217 passes, on the movement core seat 202 has a large gap with the outer diameter of the threaded part of the fifth screw 217 (the single-sided gap is 0.4 mm in the embodiment of the present application), so as to facilitate the calibration of the position between the infrared movement core 211 and the optical axis (to provide a certain adjustment space).

[0055] Further, a TYPE-C interface 210 is fixed on the infrared movement core 211 through a sixth screw 218, and a TYPE-C washer 207 is arranged between the TYPE-C interface 210 and the infrared movement core 211.

[0056] Further, the control panel 4 is fixed on the lens body 201 through a seventh screw 219.

[0057] Further, the control panel 4 comprises a mirror cover plate 401, and a key group, an encoder group 7, and a wireless communication group (WIFI group in the embodiment) fixed to the mirror cover plate 401.

[0058] The mirror cover plate 401 is fixed to the mirror body 201 by a seventh screw 219.

[0059] The key group comprises a key circuit board 406 and a first key cover 402, the key circuit board 406 is fixed to the mirror cover plate 401 by an eighth screw 405, and the wireless communication group comprises a wireless communication cover plate (WIFI cover 403 in the embodiment) connected to the mirror cover plate 401.

[0060] The encoder group 7 comprises an encoder 709 and an encoder hand wheel group, the encoder 709 is fixed to the mirror cover plate 401, and a control end of the encoder 709 is connected to the encoder hand wheel 701 group.

[0061] Further, a first key gasket 404 is arranged between the first key cover 402 and the key circuit board 406, the first key gasket 404 is pasted to a key bottom of the first key cover 402, and is used for enhancing an operation feeling of the key.

[0062] Further, the encoder 709 is fixed to the mirror cover plate 401 by an encoder first compression ring 707, the encoder hand wheel 701 group comprises the encoder hand wheel 701, a second key cover 702, and an encoder key compression ring 704, the second key cover 702 is fixed to the encoder hand wheel 701 by the encoder key compression ring 704, and a waist-shaped groove is arranged on the encoder key compression ring 704 and connected to the control end of the encoder 709.

[0063] Further, a second key gasket 703 is arranged between the second key cover 702 and the encoder 709.

[0064] Further, the encoder group 7 comprises an encoder second compression ring 705 and a tenth screw 708, the encoder second compression ring 705 is fixed to the mirror cover plate 401, a side surface of the encoder second compression ring 705 is provided with an annular notch, the encoder hand wheel 701 is sleeved on the encoder second compression ring 705, the tenth screw 708 penetrates through the encoder hand wheel 701 and an inner end of the tenth screw 708 is located in the annular notch, and the tenth screw 708 is used for limiting an axial position of the encoder hand wheel 701 without affecting rotation of the encoder hand wheel 701.

[0065] Further, a third sealing ring 706 is arranged on the side surface of the encoder second compression ring 705, and the third sealing ring 706 is located between the encoder second compression ring 705 and the encoder hand wheel 701.

[0066] Further, the power supply set comprises a battery, a battery compartment, a battery cover set 8, and an electrode set 9. The battery compartment is located on the side of the mirror body 201. The electrode set 9 is arranged at the bottom of the battery compartment. The battery is arranged in the battery compartment. The battery cover set 8 is detachably connected with the battery compartment. The battery cover set 8 and the electrode set 9 are electrically connected with the negative electrode and the positive electrode of the battery respectively.

[0067] Further, the electrode set 9 comprises an electrode pad seat 904, a positive electrode sheet 903, an electrode spring 804, an electrode pressing ring 902, and an electrode sleeve ring 901 arranged in sequence at the bottom of the battery compartment. The positive electrode sheet 903 is located in the electrode pad seat 904. The electrode spring 804 is welded on the positive electrode sheet 903. The electrode sleeve ring 901 is provided with an annular groove on the outer side. The electrode pressing ring 902 is sleeved on the annular groove of the electrode sleeve ring 901, and the outer side of the electrode pressing ring is threadedly connected with the battery compartment (the electrode sleeve ring 901 presses the electrode sheet and the electrode pad seat 904 towards the bottom of the battery compartment). The electrode pad seat 904 and the electrode pressing ring 902 are made of ABS material, and the electrode sleeve ring 901 is made of silicone rubber material, which have insulation effect.

[0068] Further, the battery cover set 8 comprises a battery cover 801, an electrode spring 804, an electrode gasket 803, and a battery cover screw sleeve 802. The inner bottom of the battery cover 801 is provided with a groove. The electrode spring 804 is arranged in the groove of the battery cover 801. The electrode gasket 803 and the battery cover screw sleeve 802 are fixed in sequence on the inner side of the battery cover 801.

[0069] Further, the electrode gasket 803 is in interference fit with the battery, which is used to press the battery and prevent the battery from loosening due to shooting vibration.

[0070] Further, the outer side of the battery cover screw sleeve 802 is provided with a fourth sealing ring 805.

[0071] Further, the electrode spring 804 in the battery cover set 8 and the electrode set 9 is electrically connected with the negative electrode and the positive electrode of the battery respectively. The inner thread and the groove of the battery cover 801 are subjected to oxygen breaking treatment. The battery cover screw sleeve 802 is fixed with the battery cover 801 by conductive glue. The battery cover screw sleeve 802 is connected with the battery compartment through the mirror body screw sleeve 204 made of conductive material (copper in this embodiment). A threaded hole subjected to oxygen breaking treatment is arranged on the mirror body 201. A third screw 215 capable of conducting electricity is connected in the threaded hole. The third screw 215 fixes the negative electrode sheet 214 on the mirror body 201. The negative electrode wire is welded on the negative electrode sheet.

[0072] Further, the positive electrode wire is welded on the positive electrode sheet 903. The positive electrode wire is inserted into the mirror body 201 through the lead groove with a hole on the side of the battery compartment. The lead groove is closed by a lead groove sealing plate. The lead groove sealing plate 205 is fixed with the mirror body 201 by the second screw 213. The sealing gasket 208 is arranged between the lead groove sealing plate 205 and the mirror body 201.

[0073] Further, the focusing group 6 comprises an inner focusing gear 602, a focusing hand wheel 601, a focusing screw 604, the inner focusing gear 602 is rotationally connected with the mirror body 201, the focusing hand wheel 601 is fixed outside the inner focusing gear 602, a curved groove is arranged on the inner side surface of the inner focusing gear 602, a straight groove is arranged on the mirror body 201, one end of the focusing screw 604 is located in the curved groove, and the other end of the focusing screw 604 passes through the straight groove and is threadedly connected with the infrared objective lens group 1.

[0074] Further, the inner focusing gear 602 is rotationally connected with the mirror body 201 through the focusing pressing ring 603 threadedly connected with the mirror body 201.

[0075] Further, the focusing hand wheel 601 is fixed with the inner focusing gear 602 through the ninth screw 606, the outer side of the ninth screw 606 is provided with a focusing scale 605, and the focusing scale 605 is connected with the focusing hand wheel 601.

[0076] Further, the first sealing ring 607 is arranged between the inner focusing gear 602 and the mirror body 201, and the second sealing ring 608 is arranged between the focusing hand wheel 601 and the mirror body 201.

[0077] Further, the focusing spring 609 is arranged between the infrared objective lens group 1 and the mirror body 201.

[0078] Further, the connecting bracket group 10 comprises a connecting seat 1001, and the connecting seat 1001 is provided with an opening ring respectively connected with the ocular lens group 5 and an external white light sighting telescope at two ends, and the opening ring is provided with a locking mechanism.

[0079] Further, the inner wall of the opening ring is pasted with a non-slip cloth 1009.

[0080] Further, the locking mechanism comprises a locking handle 1002, a cylindrical pin 1006, a locking screw 1003, a gasket 1007, a wave-shaped gasket 1008, a locking nut 1004 and a retreat stop nut 1005, the opening of the opening ring is provided with a boss with a through hole, one end of the locking screw 1003 is rotationally connected with the locking handle 1002 through the cylindrical pin 1006, the other end of the locking screw 1003 passes through the gasket 1007, the boss of the opening ring and the wave-shaped gasket 1008 in sequence, and then is threadedly connected with the locking nut 1004 and the retreat stop nut 1005 in sequence.

[0081] Further, the gasket 1007 is made of steel, so as to reduce the abrasion between the locking handle 1002 and the boss of the opening ring.

[0082] Further, the locking handle 1002 and the cylindrical pin 1006 are in interference fit.

[0083] Further, the battery compartment is at a certain oblique angle compared with the axial direction of the mirror body 201, so that the infrared front lens can normally replace the battery when the connecting bracket group 10 is installed.

[0084] Further, the mirror body 201 is provided with an interface with a certain hole distance (40mm in this embodiment), and the interface of the mirror body 201 is fixed with a standard picatinny rail 206 through a first screw 212; the standard picatinny rail 206 can install external equipment to expand the function of the infrared front mirror; in other embodiments of the utility model, the interface can also adopt other types of connecting structures.

[0085] Further, the eyepiece group 5 moves axially by rotating in the rear lens group 3 (for adjusting the diopter), and the rear lens group 3 comprises a retreat stop ring for preventing the eyepiece group 5 from rotating out.

[0086] Further, the eyepiece group 5 is connected with a diopter adjustment hand wheel at the rear end, and the rear end of the diopter adjustment hand wheel is connected with an eyepiece cover; it should be understood that when the infrared front mirror is assembled with the connecting bracket group 10, the eyepiece cover should be removed first.

[0087] Further, the eyepiece optical system in the eyepiece group 5 comprises a first meniscus lens 50101, a double convex lens 50102, a second meniscus lens 502, a third meniscus lens 503, a fourth meniscus lens 504 and a fifth meniscus lens 505 arranged in sequence from the human eye to the display screen, wherein the first meniscus lens 50101 and the double convex lens 50102 are tightly bonded as a cemented lens.

[0088] Further, the focal length fa of the cemented lens satisfies: 58.71mm < fa < 64.89mm;

[0089] The focal length fb of the second meniscus lens 502 satisfies: 32.34mm < fb < 35.75mm;

[0090] The focal length fc of the third meniscus lens 503 satisfies: 17.80mm < fc < 19.67mm;

[0091] The focal length fd of the fourth meniscus lens 504 satisfies: 40.24mm < fd < 44.48mm;

[0092] The focal length fe of the fifth meniscus lens 505 satisfies: 29.36mm < fe < 32.45mm.

[0093] Further, the air gap of the cemented lens and the second meniscus lens 502 is 0.3±0.03mm, the air gap of the second meniscus lens 502 and the third meniscus lens 503 is 2.73±0.03mm, the air gap of the third meniscus lens 503 and the fourth meniscus lens 504 is 3.54±0.03mm, and the air gap of the fourth meniscus lens 504 and the fifth meniscus lens 505 is 0.3±0.03mm.

[0094] The eyepiece optical system used in the embodiment adopts a deformed Kepler eyepiece structure, gradually increases the number of field lenses, makes light rays smoothly project, reduces light deflection angle, effectively guarantees image quality in the case of large exit pupil, and achieves 10 times magnification, 25mm focal length and 20mm exit pupil distance.

[0095] It should be noted that, according to the needs of implementation, each step / component described in the present application can be split into more steps / components, or two or more steps / components or part operations of the steps / components can be combined into a new step / component, to achieve the purpose of the present application.

[0096] Those skilled in the art can easily understand that the above description is only a preferred embodiment of the present application, and is not intended to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An infrared front lens characterized by, The application relates to a multifunctional infrared sighting telescope, which comprises a mirror body group, a rear mirror group and a connecting support group. The rear mirror group is connected to the rear end of the mirror body group, and the two ends of the connecting support group are respectively detachably connected with an infrared front lens and an external white light sighting telescope. The mirror body group comprises a mirror body, an infrared objective lens group, an infrared core group arranged in the mirror body in sequence, a control panel arranged on the side surface of the mirror body, a power supply group, a focusing group and a wireless communication group. The rear mirror group is provided with an eyepiece group and a display screen.

2. The infrared frontoscope according to claim 1, characterized in that The infrared core group comprises an infrared core and a core seat, the infrared core is fixed on the core seat, and the core seat is fixed on the mirror body.

3. The infrared frontoscope according to claim 1, characterized in that The control panel comprises a mirror body cover plate, a key group and an encoder group fixed on the mirror body cover plate, and a wireless communication group. The mirror body cover plate is fixed on the mirror body. The key group comprises a key circuit board and a first key cover, the wireless communication group comprises a wireless communication cover plate connected to the mirror body cover plate. The encoder group comprises an encoder and an encoder hand wheel group, the encoder is fixed on the mirror body cover plate, and the control end of the encoder is connected with the encoder hand wheel group.

4. The infrared frontoscope of claim 1, wherein, The power supply group comprises a battery, a battery compartment, a battery cover group and an electrode group, the battery compartment is arranged on the side surface of the mirror body, the electrode group is arranged on the bottom of the battery compartment, the battery is arranged in the battery compartment, and the battery cover group is detachably connected with the battery compartment.

5. The infrared frontoscope of claim 1, wherein The electrode group is electrically connected with the negative electrode and the positive electrode of the battery respectively.

6. The infrared frontoscope of claim 1, wherein The connecting support group comprises a connecting seat, the two ends of the connecting seat are respectively provided with open rings connected with the eyepiece group and an external white light sighting telescope, and the open rings are provided with locking mechanisms.

7. The infrared frontoscope according to claim 4, characterized in that The battery compartment is arranged at a certain oblique angle relative to the axial direction of the mirror body.

8. The infrared frontoscope of claim 1, wherein, The mirror body is provided with interfaces with a certain hole distance, and the interfaces of the mirror body are fixed with standard Picatinny guide rails.

9. The infrared frontoscope of claim 1, wherein, The optical system of the eyepiece group comprises a first meniscus lens, a biconvex lens, a second meniscus lens, a third meniscus lens, a fourth meniscus lens and a fifth meniscus lens arranged in sequence from the human eye to the display screen, and the first meniscus lens and the biconvex lens are tightly bonded as a cemented lens.

10. The infrared frontoscope of claim 1, wherein The focal length fa of the cemented lens satisfies 58.71mm < fa < 64.89mm. The focal length fb of the second meniscus lens satisfies 32.34mm < fb < 35.75mm. The focal length fc of the third meniscus lens satisfies 17.80mm < fc < 19.67mm. The focal length fd of the fourth meniscus lens satisfies 40.24mm < fd < 44.48mm. The focal length fe of the fifth meniscus lens satisfies 29.36mm < fe < 32.45mm. The air gap between the cemented lens and the second meniscus lens is 0.3+ / -0.03mm, the air gap between the second meniscus lens and the third meniscus lens is 2.73+ / -0.03mm, the air gap between the third meniscus lens and the fourth meniscus lens is 3.54+ / -0.03mm, and the air gap between the fourth meniscus lens and the fifth meniscus lens is 0.3+ / -0.03mm.

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