Long-wave infrared electric focusing lens and imaging method thereof

Abstract

The invention relates to the field of lenses, in particular to a long-wave infrared electric focusing lens and an imaging method thereof.The long-wave infrared electric focusing lens comprises a main lens barrel, and a front fixed lens set and a focusing lens set are sequentially arranged in the main lens barrel from left to right in the light incidence direction; the front fixed lens group comprises a positive lens A and a negative lens B which are sequentially arranged from left to right; the focusing lens group is provided with a positive lens C; the right side end of the main lens cone is provided with a connecting flange. The lens can realize 100mm fixed-focus imaging, and the focusing group can move to search and track objects at different distances at different temperatures.

Description

Technical Field

[0001] The present invention relates to the field of lenses, and particularly to a long-wave infrared motorized focusing lens and an imaging method thereof. Background Art

[0002] In an infrared imaging system, an optical system with an autofocus function can quickly locate and search for an object within a specific distance range. The movement of the focusing group can ensure that the image is not out of focus at different working environment temperatures, and can quickly detect, identify, track, and aim at the target. However, there is no thermal imaging lens that can be applied to the fields of forest fire prevention and border and coastal defense. Summary of the Invention

[0003] The purpose of the present invention is to provide a long-wave infrared motorized focusing lens and an imaging method thereof. The lens can achieve fixed-focus imaging at 100 mm, and the movement of the focusing group can realize searching and tracking objects at different distances at different temperatures.

[0004] The technical solution of the present invention is as follows: A long-wave infrared motorized focusing lens includes a main lens barrel. Inside the main lens barrel, a front fixed lens group and a focusing lens group are sequentially arranged from left to right along the light incident direction. The front fixed lens group includes a positive lens A and a negative lens B arranged sequentially from left to right. The focusing lens group is provided with a positive lens C. A connecting flange is installed at the right end of the main lens barrel.

[0005] Further, the air gap between the positive lens A and the negative lens B is 38.66 mm, and the air gap between the negative lens B and the positive lens C is 19.54 mm - 27.04 mm.

[0006] Further, a first annular step surface for abutting against the circumferential part of the right end of the positive lens A is provided inside the main lens barrel, and an A-piece retaining ring for fixing the positive lens A is screwed inside the main lens barrel.

[0007] Further, a second annular step surface for abutting against the circumferential part of the right end of the negative lens B is provided inside the main lens barrel, and a B-piece retaining ring for fixing the negative lens B is screwed inside the main lens barrel.

[0008] Further, a focusing lens holder is provided inside the main lens barrel. The positive lens C is installed inside the focusing lens holder. A third annular step surface for abutting against the circumferential part of the right end of the positive lens C is provided inside the focusing lens holder, and a C-piece retaining ring for fixing the positive lens C is screwed inside the focusing lens holder.

[0009] Further, a focusing mechanism cooperating with the focusing lens holder is also provided on the main lens barrel.

[0010] Further, the focusing mechanism includes a microswitch, a motor bracket disposed above the main lens barrel, and a motor and a potentiometer mounted on the motor bracket. A cam is sleeved outside the main lens barrel, and a cam groove is formed on the cam. A guide pin connected to the focusing lens base is disposed in the cam groove. An output end of the motor is provided with a motor gear, and an output shaft of the potentiometer is provided with a potentiometer gear. The motor gear and the potentiometer gear are meshed with the cam through a pulley mounted on the motor bracket.

[0011] Further, a focusing stop pin is provided on the cam, and a silica gel sleeve is provided on the focusing stop pin.

[0012] An imaging method of a long-wave infrared motorized focusing lens, in which light passes through a positive lens A, a negative lens B, and a positive lens C in sequence and then forms an image.

[0013] An imaging method of a long-wave infrared motorized focusing lens, in which the focusing lens group quickly moves to a corresponding position according to the value calibrated by the potentiometer according to the ambient temperature, ensuring clear imaging under different temperature conditions; when the focusing lens group moves to the upper and lower limit positions, the focusing stop pin contacts the microswitch to cut off the power supply.

[0014] Compared with the prior art, the present invention has the following advantages: The lens realizes 100 mm fixed-focus imaging, and the movement of the focusing group can realize searching and tracking of objects at different distances under different temperatures, so that the lens can be applied to the fields of forest fire prevention and border defense. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is the optical system diagram of the present invention; Figure 2 is the cross-sectional view of the lens of the present invention; Figure 3 is the motorized focusing mechanism diagram of the present invention; Figure 4 is the isometric view of the lens of the present invention; In the figure: 1 - positive lens A, 2 - negative lens B, 3 - positive lens C, 4 - main lens barrel, 5 - connecting flange, 6 - first annular step surface, 7 - A-piece retaining ring, 8 - second annular step surface, 9 - B-piece retaining ring, 10 - focusing lens base, 11 - third annular step surface, 12 - C-piece retaining ring, 13 - microswitch, 14 - motor bracket, 15 - motor, 16 - potentiometer, 17 - cam, 18 - cam groove, 19 - guide pin, 20 - motor gear, 21 - potentiometer gear, 22 - pulley, 23 - focusing stop pin, 24 - silica gel sleeve, 25 - switch bracket. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0016] To make the above features and advantages of the present invention more understandable, the following specific embodiments are given in conjunction with the accompanying drawings and described in detail as follows, but the present invention is not limited thereto.

[0017] Reference Figures 1 to 4 A long-wave infrared motorized focus lens, comprising a main lens barrel 4. Inside the main lens barrel, a front fixed lens group and a focus lens group are sequentially arranged from left to right along the light incident direction. The front fixed lens group includes a positive lens A1 and a negative lens B2 sequentially arranged from left to right. The focus lens group is provided with a positive lens C3. A connecting flange 5 is installed at the right end of the main lens barrel, and the entire lens is connected to the movement through the connecting flange.

[0018] In this embodiment, the air gap between the positive lens A and the negative lens B is 38.66 mm, and the air gap between the negative lens B and the positive lens C is 19.54 mm - 27.04 mm.

[0019] In this embodiment, a first annular step surface 6 for abutting against the circumferential part of the right end of the positive lens A is arranged inside the main lens barrel, and an A-piece retaining ring 7 for abutting against the circumferential part of the left end of the positive lens A is screwed inside the main lens barrel, so as to fix the positive lens A by the cooperation of the A-piece retaining ring and the first annular step surface 6. See Figure 2 .

[0020] In this embodiment, a second annular step surface 8 for abutting against the circumferential part of the right end of the negative lens B is arranged inside the main lens barrel, and a B-piece retaining ring 9 for abutting against the circumferential part of the left end of the negative lens B is screwed inside the main lens barrel, so as to fix the positive lens B by the cooperation of the B-piece retaining ring and the second annular step surface. See Figure 2 .

[0021] In this embodiment, a focus lens holder 10 is arranged inside the main lens barrel. The positive lens C is installed inside the focus lens holder. A third annular step surface 11 for abutting against the circumferential part of the right end of the positive lens C is arranged inside the focus lens holder, and a C-piece retaining ring 12 for abutting against the circumferential part of the left end of the positive lens C is screwed inside the focus lens holder, so as to fix the C-piece retaining ring 12 by the cooperation of the C-piece retaining ring and the third annular step surface. See Figure 2 .

[0022] In this embodiment, a focus adjustment mechanism cooperating with the focus lens holder is further arranged on the main lens barrel. The focus adjustment mechanism includes a microswitch 13 installed on the main lens barrel through a switch holder 25, a motor holder 14 arranged above the main lens barrel, a motor 15 and a potentiometer 16 installed on the motor holder. A cam 17 is sleeved outside the main lens barrel. The cam and the main lens barrel are ground and matched to ensure the feel and consistency during the actuation process. The cam is limited by the connecting flange. The cam has a cam groove 18, and a guide pin 19 connected to the focus lens holder is arranged inside the cam groove. A motor gear 20 is provided at the output end of the motor, and a potentiometer gear 21 is arranged on the output shaft of the potentiometer. The motor gear and the potentiometer gear are meshed with the cam through a idler wheel 22 installed on the motor holder. See Figure 3 .

[0023] In this embodiment, the focusing lens group can quickly move to the corresponding position according to the value calibrated by the potentiometer based on the ambient temperature, ensuring clear imaging under different temperature conditions.

[0024] In this embodiment, a focusing stop pin 23 is provided on the cam. When the focusing group moves to the upper and lower limit positions, the focusing stop pin contacts the microswitch to cut off the power supply, avoiding motor jamming. A silica gel sleeve 24 is provided on the focusing stop pin to buffer the movement contact between the stop pin and the switch. See Figure 4 .

[0025] In this embodiment, the lens can achieve the following optical specifications: (1) Operating wavelength band: 8um - 12um; (2) Focal length: 100mm; (2) Detector: Mid-wave infrared cooled detector 640x512 12um; (3) Field of view: 4.38° (H) × 3.51° (V); (4) Relative aperture: F1.2.

[0026] In this embodiment, the lens parameters of the front fixed lens group and the focusing lens group are shown in the following table: Table 1.

[0027] As shown in Table 1, when the radius of curvature is positive, the center of the surface type is on the imaging surface side; conversely, the radius of curvature is negative. The aspherical surface type equations involved in the table are: .

[0028] The specific parameters of the aspherical part shown in Table 1 are described as follows: Among them, for S4: c = 1 / R, R = 28.098, k = 0, A0 = 0, A1 = 4.0343357E-006, A2 = 1.4838816E-009, A3 = 6.4098247E-011, A4 = -2.1999609E-013, A5 = 4.6913364E-016; Among them, for S6: c = 1 / R, R = 392.938, k = 0, A0 = 0, A1 = -3.0816753E-006, A2 = 3.1332009E-009, A3 = -3.7614253E-011, A4 = 1.7295434E-013, A5 = -3.264859E-016.

[0029] An imaging method of a long-wave infrared motorized focusing lens. Light passes through positive lens A, negative lens B, and positive lens C in sequence and then forms an image.

[0030] The above are only the preferred embodiments of the present invention. For those of ordinary skill in the art, according to the teachings of the present invention, designing different forms of long-wave infrared motorized focus lenses and their imaging methods does not require creative labor. Without departing from the principles and spirit of the present invention, all equal changes, modifications, substitutions, and variations made within the scope of the patent application of the present invention shall fall within the scope covered by the present invention.

Claims

1. A long-wave infrared motorized focus lens, comprising a main lens barrel, characterized in that, Inside the main lens barrel, a front fixed lens group and a focusing lens group are sequentially arranged from left to right along the light incident direction; the front fixed lens group includes a positive lens A and a negative lens B sequentially arranged from left to right; the focusing lens group is provided with a positive lens C; a connecting flange is installed at the right end of the main lens barrel.

2. The long-wave infrared motorized focusing lens according to claim 1, wherein The air gap between the positive lens A and the negative lens B is 38.66 mm, and the air gap between the negative lens B and the positive lens C is 19.54 mm - 27.04 mm.

3. The long-wave infrared motorized focusing lens according to claim 1 or 2, characterized in that, Inside the main lens barrel, a first annular step surface is provided for abutting against the circumferential part of the right end of the positive lens A, and an A-piece retaining ring for fixing the positive lens A is screwed inside the main lens barrel.

4. The long-wave infrared motorized focusing lens according to claim 3, wherein, Inside the main lens barrel, a second annular step surface is provided for abutting against the circumferential part of the right end of the negative lens B, and a B-piece retaining ring for fixing the negative lens B is screwed inside the main lens barrel.

5. A long-wave infrared motorized focusing lens according to claim 1, 2 or 4, characterized in that, Inside the main lens barrel, a focusing lens holder is provided, the positive lens C is installed inside the focusing lens holder, a third annular step surface is provided inside the focusing lens holder for abutting against the circumferential part of the right end of the positive lens C, and a C-piece retaining ring for fixing the positive lens C is screwed inside the focusing lens holder.

6. The long-wave infrared motorized focusing lens according to claim 5, wherein, A focusing mechanism matched with the focusing lens holder is further provided on the main lens barrel.

7. A long-wave infrared motorized focusing lens and its imaging method according to claim 6, characterized in that, The focusing mechanism includes a microswitch, a motor bracket arranged above the main lens barrel, and a motor and a potentiometer installed on the motor bracket. A cam is sleeved outside the main lens barrel. The cam has a cam groove. A guide pin connected to the focusing lens holder is arranged inside the cam groove. The output end of the motor is provided with a motor gear, and the output shaft of the potentiometer is provided with a potentiometer gear. The motor gear and the potentiometer gear are meshed with the cam through a pulley installed on the motor bracket.

8. A long-wave infrared motorized focus lens and its imaging method according to claim 7, characterized in that A focusing stop pin is provided on the cam, and a silica gel sleeve is provided on the focusing stop pin.

9. An imaging method for a long-wave infrared motorized focus lens according to any one of claims 1-8, characterized in that, Light passes through the positive lens A, the negative lens B, and the positive lens C in sequence and then forms an image.

10. An imaging method for a long-wave infrared motorized focusing lens according to any one of claims 7 or 8, characterized in that, The focusing lens group quickly moves to the corresponding position according to the value calibrated by the potentiometer according to the ambient temperature to ensure clear imaging under different temperature conditions; when the focusing lens group moves to the upper and lower limit positions, the focusing stop pin contacts the microswitch to cut off the power supply.

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