Optical fog-penetrating zoom lens

Abstract

The invention discloses a technical solution of an optical fog-penetrating zoom lens, which is composed of nine lenses with different shapes and structure parameters, and the lenses are arranged, combined and designed according to a certain imaging rule. Comprising a zoom lens group G1 and a compensation lens group G2, a diaphragm is located between the G1 and the G2, and a three-time zoom function of the lens is realized through regular movement of the G1 and the G2 relative to the diaphragm. The zoom group G1 is composed of three spherical lenses L1, L2 and L3, and the compensation group G2 is composed of six spherical lenses L4, L5, L6, L7, L8 and L9. L1, L2, L5 and L7 are lenses with negative focal power, and the rest are lenses with positive focal power. The visible light wave band and the fog-penetrating wave band are configured with four wavelengths of 0.489 [mu] m, 0.588 [mu] m, 0.656 [mu] m and 0.9 [mu] m in total. Through multispectral fusion design and aberration correction, the positions of the diaphragm and the image plane are kept immobile and the image plane drift is zero in the continuous conversion process of the wave band and the focal length, so that simultaneous high-definition imaging of far and near monitored targets by visible light and fog-penetrating wave bands is realized.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of optical instruments, and particularly relates to a visible light to near-infrared fog-penetrating zoom imaging lens. BACKGROUND

[0002] The optical fog-penetrating lens refers to a lens with high transmittance to fog-penetrating near-infrared light (700nm-950nm) and capable of controlling the clear imaging of the light in the fog-penetrating waveband on an image sensor. The zoom lens generally refers to a lens capable of realizing the clear imaging of a monitoring target at a long or short distance. The optical fog-penetrating zoom lens can ensure that the lens has high transmittance from visible light to the fog-penetrating near-infrared waveband, and the lens system has good correction of aberrations such as spherical aberration, chromatic aberration and coma in the wide waveband. During the continuous change of the waveband and focal length, the lens can clearly image, and the image plane does not displace.

[0003] The conventional fog-penetrating continuous zoom optical system usually adopts a four-group complex structure of front and rear fixed groups, a zoom group and a compensation group, and uses a special lens correction mirror structure for the fog-penetrating function. Therefore, it is difficult to make the total length and volume extremely compact, the mechanical structure is complex, and the cost is extremely high.

[0004] The optical fog-penetrating zoom lens can realize the tracking observation and clear imaging of a monitoring target without focusing under normal weather and severe weather such as fog, water vapor, rain and snow, and is mainly used for the safety prevention and monitoring of power failure, forest fire, navigation and the like. SUMMARY

[0005] To solve the above technical problems, the present application provides an optical fog-penetrating zoom lens composed of nine lenses with different shapes, different size parameters and different materials and a diaphragm for controlling the light amount, which are arranged and combined according to certain imaging rules to realize the three times zoom function of 5mm-15mm, and during the continuous change of the visible light and near-infrared fog-penetrating waveband and focal length, the lens can accurately image on a 1 / 2 inch CMOS image sensor (the effective receiving diagonal line size is 7.2mm), and the diaphragm position and image plane position remain unchanged to realize the high-definition tracking imaging and fog-penetrating imaging function of a monitored target.

[0006] An optical haze-transparent zoom lens comprises a G1 zoom lens group and a G2 compensation lens group, a diaphragm arranged between the G1 zoom lens group and the G2 compensation lens group to control the amount of light entering the lens, the G1 zoom lens group is composed of three spherical lenses L1, L2 and L3, the G2 compensation lens group is composed of six spherical lenses L4, L5, L6, L7, L8 and L9, the L6 and L7 form an optical cemented lens group, and the rest are single lenses. L1, L2, L5 and L7 are negative focal length lenses, and L3, L4, L6, L8 and L9 are positive focal length lenses. The focal length value of L1 is -30.3; the focal length value of L2 is -23.5; the focal length value of L5 is -39.8; the focal length value of L7 is -14; the focal length value of L3 is 44.6; the focal length value of L4 is 20.9; the focal length value of L6 is 24.3; the focal length value of L8 is 19.6; the focal length value of L9 is 72.4; and the focal length of the cemented lens group composed of L6 and L7 is -84.4.

[0007] The L1 lens adopts a lanthanide optical material, the refractive index nd value of which is 1.66, and the dispersion coefficient Vd value of which is 57.4. The L2, L4, L6, L8 and L9 adopt the same heavy crown type optical material, the refractive index nd value of which is 1.62, and the dispersion coefficient Vd value of which is 60.4. The L3, L5 and L7 adopt the same heavy flint type optical material, the refractive index nd value of which is 1.81, and the dispersion coefficient Vd value of which is 25.5. The heavy flint optical material is one of the flint optical glasses, and has a high refractive index and a large dispersion rate.

[0008] The lens focal length is realized from 5mm to 15mm three times zoom function through the regular movement of the G1 zoom lens group and the G2 compensation lens group relative to the diaphragm. When the lens focal length changes from 5mm to 15mm, the distance of G1 relative to the diaphragm changes from 30.16 to 1.16; the distance of G2 relative to the diaphragm changes from 8.81 to 1.2; and the distance of G2 relative to the image surface changes from 4.03 to 11.56.

[0009] The present application configures four wavelengths of 0.489μm, 0.588μm, 0.656μm and 0.9μm in the visible light and haze-transparent waveband. The main wavelength is 0.588μm, which is used to calculate the related optical parameters of the lens. The three wavelengths of 0.489μm, 0.588μm and 0.656μm represent the visible light waveband, and 0.9μm represents the haze-transparent waveband. In this wide waveband, the lens realizes high transmittance design and high-definition imaging effect.

[0010] The focal length is provided with three data observation points, which are 5mm, 10mm and 15mm respectively; during the continuous conversion of the wave band and the focal length, the intervals d1, d2 and d3 between the zoom group G1, the diaphragm, the compensation group G2 and the image surface change, but the positions of the diaphragm and the image surface remain unchanged, the image surface does not drift, but with the focal length changing from 5mm to 15mm, the diaphragm diameter changes a little, the F number changes from 1.8 to 2.4, so that the lens has sufficient light quantity.

[0011] The optical structure is composed of 9 spherical lenses with different thicknesses, and the spherical radii are positive and negative, and the absolute values of the radii are different from 9.6 to 74.28. The centering coefficients of each lens are greater than 0.06, and the lenses of the G1 zoom lens group and the G2 compensation lens group are assembled in two lens barrels respectively, three lenses in the front group G1 are assembled in a stepped lens barrel, and six lenses in the rear group G2 have the same mechanical outer diameter and are assembled in a lens barrel with the same inner diameter.

[0012] The field of view is set to select the image height mode, and the field of view data is set to three, namely zero field of view, 0.7 field of view and full field of view, and the maximum field of view image height value is set to 3.6mm, and the 0.7 field of view image height value is set to 2.5mm.

[0013] The aperture is set to select the image square space F# mode, when the focal length changes from 5mm to 15mm, the F# changes from 1.8 to 2.4, so multiple structures are configured. F#1.8 corresponds to 5mm focal length, F#2.1 corresponds to 10mm focal length, and F#2.4 corresponds to 15mm focal length, so as to ensure that the lens has sufficient light quantity during the zoom design process.

[0014] The object side field angle of the lens reaches the maximum (the maximum field angle is 72 degrees) when the focal length is 5mm, at this time, the lens image surface relative luminance value design result exceeds 68%, when the focal length is 10mm and 15mm, the lens image surface relative luminance design result at the maximum field of view exceeds 75%. The uniformity of the image surface luminance is maintained.

[0015] The imaging quality design result of the lens reaches the national high-definition standard. When the spatial frequency is 110 lp / mm, the MTF values of the long, medium and short focal lengths and each wave band and each field of view are all above 0.35. And the meridian and sagittal curves of MTF decrease monotonously with the increase of the spatial frequency.

[0016] The advantages of the present application are that: The present application realizes the fog-penetrating function through the visible light and near-infrared light wave band (0.489μm-0.9μm) multi-spectrum fusion, which avoids the complex structure of the fog-penetrating part caused by adding a correction lens and the like.

[0017] The application adopts two groups of mobile simple optical structures of zooming and compensation, and the total number of lenses used is 9, realizes the functions of zooming and fog-transmitting confocal high-definition imaging, and greatly reduces the cost.

[0018] All the lenses used in the application are spherical lenses, and only three kinds of conventional optical glass are used for lens material, and the lens processing and lens assembly process are good, which greatly reduces the manufacturing error and improves the production yield. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the application, the drawings needed for the embodiment description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings: Figure 1 The optical structure composition and movement schematic diagram of a fog-transmitting zoom lens implemented by the application; Figure 2 The optical structure schematic diagram of a fog-transmitting zoom lens implemented by the application in a short focal length 5mm state; Figure 3 The optical structure schematic diagram of a fog-transmitting zoom lens implemented by the application in a medium focal length 10mm state; Figure 4 The optical structure schematic diagram of a fog-transmitting zoom lens implemented by the application in a long focal length 15mm state; Figure 5 The 3D optical structure schematic diagram of a fog-transmitting zoom lens implemented by the application in a long, medium and short focal length state; Figure 6 The transfer function curve diagram of a fog-transmitting zoom lens implemented by the application in a short focal length 5mm state; Figure 7 The transfer function curve diagram of a fog-transmitting zoom lens implemented by the application in a medium focal length 10mm state; Figure 8 The transfer function curve diagram of a fog-transmitting zoom lens implemented by the application in a long focal length 15mm state; Figure 9 The image plane relative luminance curve diagram of a fog-transmitting zoom lens implemented by the application in a short focal length 5mm state; Figure 10 The image plane relative luminance curve diagram of a fog-transmitting zoom lens implemented by the application in a medium focal length 10mm state; Figure 11 The image plane relative luminance curve diagram of a fog-transmitting zoom lens implemented by the application in a long focal length 15mm state. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1: Please refer to Figures 1-11 The optical technical specifications of this invention include: lens imaging sensor: 1 / 2.5-inch CMOS chip (effective diagonal 7.2 mm); lens focal length variation range: 5 mm to 15 mm; lens F# variation range: 1.8 to 2.4; lens imaging for visible light and fog-penetrating bands (fog-penetrating band: 700 to 950 nm); lens back working distance: greater than 4 mm; total length of the lens system: less than 100 mm; maximum defocus value of the image plane during lens zoom: less than 0.2 mm; lens imaging quality: MTF > 0.3@110 lp / mm at long, medium, and short focal lengths and in all bands and fields of view.

[0022] The lens system of this invention comprises, along the optical axis from the object side to the image side, a first lens L1, a second lens L2, a third lens L3, an aperture stop, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, and a ninth lens L9. A beam of light at infinity on the object side is refracted at different angles by lenses L1 to L9 and then imaged onto the image plane of a 1 / 2.5-inch CMOS sensor, precisely covering the effective range of the chip.

[0023] The aforementioned nine lenses are divided into two groups: the front group G1 is the zoom lens group, and the rear group G2 is the compensation lens group. The aperture stop, which controls the amount of light entering the lens, is located between G1 and G2. By the regular movement of G1 and G2 relative to the aperture stop, the lens achieves a 3x zoom function from 5mm to 15mm. When G1 and G2 move away from the aperture stop, the focal length shortens; when G1 and G2 move towards the aperture stop, the focal length length lengthens. The movement of G1 causes a change in focal length, thus altering the image plane position. The movement of G2 compensates for the change in the focusing image plane caused by the movement of G1, thereby maintaining the stability of the image plane. During the movement of G1 and G2, the parameters and relative positions of each lens in G1 and G2 remain unchanged. (See attached diagram.) Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 As shown.

[0024] The zoom group G1 is composed of three spherical lenses L1, L2 and L3, and the compensation group G2 is composed of six spherical lenses L4, L5, L6, L7, L8 and L9, wherein L6 and L7 form an optical cemented lens group, and the rest are single lenses. L1, L2, L5 and L7 are negative power lenses, and L3, L4, L6, L8 and L9 are positive power lenses. In order to reduce the cost, all of L1 to L9 are spherical lenses. As shown in the attached Figure 1 and Table 1 and Table 3.

[0025] In the implementation of the present application, the lens design is expanded to the near-infrared band in the visible light band to realize the fog-penetrating function through multi-spectrum fusion. Therefore, four wavelengths of 0.489 μm, 0.588 μm, 0.656 μm and 0.9 μm are configured for the visible light and the fog-penetrating band. Among them, the main wavelength is 0.588 μm, which is used to calculate the related optical parameters of the lens. The three wavelengths of 0.489 μm, 0.588 μm and 0.656 μm represent the visible light band, and 0.9 μm represents the fog-penetrating band. Since the range of the band adapted by the lens is large, the chromatic aberration control is difficult, and therefore, in the design process, optical glass with high Abbe number is selected as much as possible as the lens material. The lens materials of L1 to L9 all use Chinese brand optical glass materials. L1 uses a lanthanide optical material, L2, L4, L6, L8 and L9 use the same heavy crown optical material, and L3, L5 and L7 use the same heavy flint optical material. The specific values are shown in Table 3.

[0026] In the implementation of the present application, the field of view is set to select the image height mode, and the field of view data is set to three, namely zero field of view, 0.7 field of view and full field of view. The maximum field of view image height value is set to 3.6 mm, and the 0.7 field of view image height value is set to 2.5 mm. In the implementation of the present application, the focal length is set to three data observation points, which are 5 mm, 10 mm and 15 mm. In the process of continuous transformation of the band and the focal length, the intervals d1, d2 and d3 between the zoom group G1, the diaphragm, the compensation group G2 and the image plane change, but the distance between the diaphragm and the image plane remains unchanged, the diaphragm position remains unchanged, and the image plane does not drift. As shown in the attached Figure 1 , Figure 5 and Table 2.

[0027] In the implementation of the present application, the aperture is set to select the image space F# mode. The selection of the image space F# mode is a way of defining the system aperture based on the characteristics of the image space. When the focal length changes from 5 mm to 15 mm, the F# changes from 1.8 to 2.4, and therefore multiple structures are configured. F# 1.8 corresponds to 5 mm focal length, F# 2.1 corresponds to 10 mm focal length, and F# 2.4 corresponds to 15 mm focal length, so as to ensure that the lens has sufficient light during the zoom design process.

[0028] In the process of changing the waveband, aperture and focal length, the chromatic aberration, coma, astigmatism and the like of the optical haze-free zoom lens are corrected by optimizing and adjusting the lens shape, structure size, material, relative position and interval between the diaphragm and the image plane of L1 to L9, restraining the lens boundary condition, controlling the optical performance parameters and aberration values of each focal length, so that the distance between the diaphragm and the image plane remains unchanged, the diaphragm position remains unchanged and the image plane does not drift in the continuous changing process from the visible light to the near-infrared waveband, the aperture from F#1.8 to F#2.4 and the focal length from 5mm to 15mm, as shown in the attached Figure 5 .

[0029] The image quality design of the optical haze-free zoom lens of the present application reaches the high-definition standard. When the spatial frequency is 110 lp / mm, the MTF values of the long, medium and short focal lengths and each waveband and each field of view are all above 0.3. As shown in the attached Figure 6 , the attached Figure 7 and the attached Figure 8 , the maximum field of view angle of the lens is achieved when the focal length is 5mm (the maximum field of view angle is 72 degrees), at this time, the design result of the relative luminance value of the image plane of the lens exceeds 68%, when the focal length is 10mm and 15mm, the design result of the relative luminance of the image plane of the lens exceeds 75% at the maximum field of view. The uniformity of the image plane luminance is maintained. As shown in the attached Figure 9 , Figure 10 , Figure 11 .

[0030] In the implementation of the present application, while the image quality of the lens is designed, the boundary conditions of the nine lenses are reasonably restrained, so that the processing technology of the nine lenses is good and the edge centering coefficients are all greater than 0.06. When the nine lenses are assembled, the three lenses in the front group G1 are assembled in a stepped barrel, the mechanical outer diameters of the six lenses in the rear group G2 are designed with the same value, so that the six lenses can be assembled in a barrel with the same inner diameter, thereby reducing the center deviation of the lens assembly and better ensuring the imaging quality of the lens, as shown in Table 1.

[0031] The implementation results of the present application are shown in Table 1.

[0032] The implementation results of the present application are shown in Table 2.

[0033] The implementation results of the present application are shown in Table 3.

[0034] The inventive results are as follows: the centering and edging coefficients of each component lens are shown in Table 4.

Claims

1. An optical haze- transparent zoom lens characterized by: The optical structure is composed of 9 spherical lenses with different shape and structure size parameters, which are L1, L2, L3, L4, L5, L6, L7, L8 and L9 respectively, wherein L6 and L7 form an optical cemented lens group, and the rest are single lenses.

2. An optical see-through varifocal lens as claimed in claim 1, characterized in that: L1, L2, L5 and L7 are negative focal length spherical lenses, L3, L4, L6, L8 and L9 are positive focal length spherical lenses, the focal length value of L1 is -30.3, the focal length value of L2 is -23.5, the focal length value of L5 is -39.8, the focal length value of L7 is -14, the focal length value of L3 is 44.6, the focal length value of L4 is 20.9, the focal length value of L6 is 24.3, the focal length value of L8 is 19.6, and the focal length value of L9 is 72.

4. The focal length value of the cemented lens group formed by L6 and L7 is -84.

4. The zoom lens group G1 and the compensation lens group G2 are provided between which a diaphragm for controlling the amount of light entering the lens is arranged, the zoom lens group G1 is composed of three lenses L1, L2 and L3, the relative positions of the three lenses are fixed, the interval between L1 and L2 is 6.69, and the interval between L2 and L3 is 2.88, the compensation lens group G2 is composed of six lenses L4, L5, L6, L7, L8 and L9, the relative positions of the six lenses are fixed, the interval between L4 and L5 is 6.69, the interval between L5 and L6 is 0.92, the interval between L7 and L8 is 1.31, and the interval between L8 and L9 is 1.

21.

3. An optical haze-free zoom lens as claimed in claim 1, 2, characterized in that: The diaphragm and the image plane position remain unchanged, and the three times zoom function of the lens focal length from 5 mm to 15 mm is realized by the regular movement of the zoom lens group G1 and the compensation lens group G2 towards the diaphragm, when the lens focal length changes from 5 mm to 15 mm, the distance of G1 relative to the diaphragm changes from 30.16 to 1.16, the distance of G2 relative to the diaphragm changes from 8.81 to 1.2, and the distance of G2 relative to the image plane changes from 4.03 to 11.

56.

4. An optical haze-free zoom lens as claimed in claim 3, characterized in that: L1 is made of a lanthanide optical material with a refractive index nd value of 1.66 and a dispersion coefficient Vd value of 57.4, L2, L4, L6, L8 and L9 are made of the same heavy crown type optical material with a refractive index nd value of 1.62 and a dispersion coefficient Vd value of 60.4, and L3, L5 and L7 are made of the same heavy flint type optical material with a refractive index nd value of 1.81 and a dispersion coefficient Vd value of 25.

5.

5. An optical haze-free zoom lens as claimed in claim 1, 2, characterized in that: Four wavelengths of 0.489 μm, 0.588 μm, 0.656 μm and 0.9 μm are configured for visible light and fog-penetrating waveband; 6. An optical see-through varifocal lens as claimed in claims 1 to 5, characterized in that: The main wavelength is 0.588 μm, which is used to calculate the relevant optical parameters of the lens, three wavelengths of 0.489 μm, 0.588 μm and 0.656 μm represent the visible light waveband, and 0.9 μm represents the fog-penetrating waveband, and in the wide waveband from 0.489 μm to 0.9 μm, the lens realizes high transmittance and high-definition imaging effect. ​ 7. An optical haze-free zoom lens as claimed in claims 1 to 5, characterized in that: The focal length is set to 5mm, 10mm and 15mm, and the image height is 3.6mm, and the relative aperture F number changes from 1.8 to 2.4 when the focal length changes from 5mm to 15mm, so that the lens has enough light quantity during zooming.

8. An optical see-through varifocal lens according to any one of claims 1 to 7, characterized in that: During the continuous change of the waveband (0.489μm~0.9μm) and the focal length (5mm~15mm), the image surface drifts to zero, the relative illumination of the image surface changes from 68% to 76%, and the imaging quality is designed: when the spatial frequency is 110 lp / mm, the MTF value of each field of view is above 0.35, and the meridian and sagittal curves of the MTF decrease monotonously with the increase of the spatial frequency.

9. An optical see-through varifocal lens according to any one of claims 1 to 8, wherein: 9 The centering processing coefficients of the spherical lenses are respectively Z L1 =0.18, Z L2 =0.32, Z L3 =0.13, Z L4 =0.2, Z L5 =0.1, Z L6 =0.17, Z L7 =0.21, Z L8 =0.22, Z L9 =0.06, and the processing performance is good.

10. An optical haze-free zoom lens as claimed in claims 1, 3, 4, characterized in that: When the lens structure is assembled, the lenses in the G1 zoom group and the G2 compensation group are respectively assembled in two lens barrels, the mechanical half diameters of the L1, L2 and L3 lenses in the G1 zoom group are 16.3, 9.9 and 9.7 respectively, and the lenses are assembled in a stepped lens barrel; the mechanical half diameters of the L4, L5, L6, L7, L8 and L9 lenses in the G2 compensation group are all 5.2, and the lenses are assembled in a lens barrel with the same inner diameter, so that the center deviation during assembly is reduced.

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