Wide-angle TOF optical imaging lens and TOF optical imaging module
By reasonably allocating the lens diopter and optimizing the lens surface type, designing a wide-angle TOF optical imaging lens, solving the problems of small imaging surface, low resolution, high cost, temperature drift and optical distortion of the existing lens, achieving high resolution, low cost and stable imaging effects.
Patent Information
- Application Number
- CN202421436955.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-21
- Publication Date
- 2025-03-14
- Estimated Expiration
- 2034-06-21
AI Technical Summary
The existing TOF lenses have problems such as insufficient imaging surface, low resolution, high cost, influence of temperature drift, incomplete extinction processing, unfit field angle matching and large optical distortion.
By reasonably allocating the diopters of each lens and optimizing the lens surface type, a wide-angle TOF optical imaging lens is designed to increase the imaging surface size, use appropriate glass materials to reduce temperature drift, control optical distortion, and paint black on the edges and steps of the lens to reduce mist.
It achieves high resolution, low cost, adaptable to wide-angle field of view and stable imaging, reduces the amount of out-of-focus in high and low temperature environments, and improves the resolution and dynamic range of the image.
Smart Images
Figure CN222618861U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of optical lenses, and in particular to a wide-angle TOF optical imaging lens and a TOF optical imaging module. Background Art
[0002] With the development of machine vision, TOF lenses are now more and more widely used in the industrial field. They can be used in industrial measurement, intelligent positioning, stereo recognition, human-computer interaction and other applications. In the field of robotics, TOF lenses can provide robots with more intelligent spatial perception and depth perception capabilities, enabling robots to better complete various operations, achieve precise operations and quick responses. Most of the existing TOF lenses have one or more of the following defects: First, the imaging surface of the existing lens is not large enough, the resolution is not high enough, and the image clarity is not high enough; second, the existing lens has a lower price as the car sales price decreases, but the lens cost is still high and the cost is expensive; third, the existing lens does not consider temperature drift or considers it poorly, and the clarity is easy to reduce when used in a high temperature environment with a high temperature or in cold weather with a low temperature; fourth, the existing lens extinction processing is not complete, and there is still stray light; and when there is interference from other light sources, it is easy to reduce the resolution; fifth, the field of view of the existing lens is too large or too small, and it cannot adapt to the field of view requirements after expanding the image plane; sixth, the optical distortion of the existing lens is large, the captured image is deformed, and it is easy to cause recognition errors. Utility Model Content
[0003] In view of the deficiencies in the prior art, the purpose of the present invention is to propose a wide-angle TOF optical imaging lens and a TOF optical imaging module. By reasonably allocating the refractive power of each lens and optimizing the surface shape of each lens, the lens can have good imaging quality, thereby solving the problems mentioned in the above background technology section.
[0004] The utility model is realized by the following technical solutions:
[0005] A wide-angle TOF optical imaging lens comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens which are arranged in sequence along an optical axis from an object side to an image side, wherein: the first lens has a negative refractive power, the object side surface of the first lens is a convex surface, and the image side surface of the first lens is a concave surface; the second lens has a negative refractive power, the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a concave surface; the third lens has a positive refractive power, the object side surface of the third lens is a convex surface, and the image side surface of the third lens is a concave surface; the fourth lens has a positive refractive power, the object side surface of the fourth lens is a concave surface, and the image side surface of the fourth lens is a convex surface; the fifth lens has a positive refractive power, the object side surface of the fifth lens is a convex surface, and the image side surface of the fifth lens is a convex surface; the sixth lens has a positive refractive power, the object side surface of the sixth lens is a concave surface, and the image side surface of the sixth lens is a concave surface.
[0006] The beneficial effects of this embodiment are: by reasonably allocating the diopter of each lens, optimizing the surface shape of each lens, etc., the imaging surface size of the optical system is increased on the basis of keeping the pixel size unchanged, a 1 / 2 inch CCD is selected, and the imaging surface diameter of the optical system is set to 8 mm.
[0007] Further, the absolute value of the ratio of the focal length f1 of the first lens to the total focal length f of the imaging lens of the optical system satisfies the following relationship: 3<|(f1 / f)|<7;
[0008] The absolute value of the ratio of the focal length f2 of the second lens to the total focal length f of the imaging lens of the optical system satisfies the following relationship: 1.7<|(f2 / f)|<5;
[0009] The absolute value of the ratio of the focal length f3 of the third lens to the total focal length f of the imaging lens of the optical system satisfies the following relationship: 0.5<|(f3 / f)|<2;
[0010] The absolute value of the ratio of the focal length f4 of the fourth lens to the total focal length f of the imaging lens of the optical system satisfies the following relationship: 2<|(f4 / f)|<5;
[0011] The absolute value of the ratio of the focal length f5 of the fifth lens to the total focal length f of the imaging lens of the optical system satisfies the following relationship: 0.2<|(f5 / f)|<2;
[0012] The absolute value of the ratio of the focal length f6 of the sixth lens to the total focal length f of the imaging lens of the optical system satisfies the following relationship: 0.3<|(f6 / f)|<2.5.
[0013] The beneficial effect of this embodiment is that the optical performance of the lens is improved by reasonably allocating the optical power of each lens.
[0014] Furthermore, the lens satisfies the following relationship: 0.8<Y / f<1.4, wherein f is the total focal length of the optical system imaging lens, and Y is the diameter of the optical system imaging surface.
[0015] The beneficial effects of this embodiment are: a larger sensor size means higher resolution, better dynamic range and less image noise. By satisfying the above formula, the lens can be adapted to a larger sensor size, thereby capturing high-quality images.
[0016] Furthermore, the lens satisfies the following relationship: 2.5<TTL / f<4.5, wherein TTL is the distance from the first lens to the imaging surface on the optical axis, and f is the total focal length of the imaging lens of the optical system.
[0017] The beneficial effect of this embodiment is that satisfying the above formula can more effectively shorten the system length and realize miniaturized optical system design.
[0018] Furthermore, the second lens and the sixth lens are made of glass material with positive Dn / Dt.
[0019] The beneficial effect of this embodiment is that satisfying the above formula can reduce the temperature drift of the entire lens optical system, and the second lens and the sixth lens compensate for the temperature drift variation caused by the base and the remaining lenses, thereby enhancing stable imaging at high and low temperatures of -40 to +85°C and reducing the amount of defocus.
[0020] Furthermore, the lens satisfies the following relationship: 40<R32<130, wherein R32 is the radius of curvature of the image side surface of the third lens.
[0021] The beneficial effect of this embodiment is that negative distortion is generated by the third lens and is used to supplement the positive distortion generated by other lenses in the system, thereby greatly reducing the total distortion of the system.
[0022] Furthermore, the lens satisfies the following relationship: 5<FOV / Y<10, wherein FOV is the field of view angle corresponding to the diameter of the diagonal imaging surface of the sensor, and Y is the diameter of the diagonal imaging surface of the sensor.
[0023] The beneficial effect of this embodiment is that by controlling the field of view angle corresponding to the diagonal imaging surface of the sensor to be 64.1°, the distortion of the optical system is controlled at the same time to meet the actual field of view angle requirement.
[0024] Furthermore, the lens satisfies the following relationship: 3<|KR1 / KR2|<4, wherein KR1 and KR2 are Conic coefficients of the object side and image side of the fourth lens, respectively.
[0025] The beneficial effects of this embodiment are as follows: the fourth lens is a glass aspherical surface, and by using a shared existing aspherical lens, there is no need to increase the inventory list, and by consuming the existing inventory, the production cost is reduced.
[0026] Furthermore, the lens edges and the entire plane steps of the first lens to the sixth lens are all coated with a black layer.
[0027] The beneficial effects of this embodiment are as follows: by applying black coating to the edges of each lens and the entire plane step, the reflection of stray light in the edge area of the lens is reduced, and similarly, the spacers between the lenses are anodized and blackened to reduce the reflection of stray light on the surface of the spacers, thereby avoiding the influence of stray light on the imaging quality.
[0028] On the other hand, the utility model provides a TOF optical imaging module, comprising a wide-angle TOF optical imaging lens as described in any of the above items and an 850nm photoelectric sensor or a 940nm photoelectric sensor. BRIEF DESCRIPTION OF THE DRAWINGS
[0029] Figure 1 This is a structural diagram of the optical system of the lens in Example 1.
[0030] Figure 2 This is the MTF curve of the lens in Example 1 at a wavelength of 850nm.
[0031] Figure 3 This is the MTF curve of the lens in Example 1 at a wavelength of 940nm.
[0032] Figure 4 This is a field curvature distortion diagram of the lens in Example 1 at a wavelength of 850nm.
[0033] Figure 5 This is a field curvature distortion diagram of the lens in Example 1 at a wavelength of 940nm.
[0034] Figure 6 This is the star point diagram of the lens in Example 1 at a wavelength of 850nm.
[0035] Figure 7 This is a relative illumination diagram of the lens in Example 1 at a wavelength of 850nm.
[0036] Figure 8 This is a structural diagram of the optical system of the lens in Example 2.
[0037] Fig. 9 This is the MTF curve of the lens in Example 2 at a wavelength of 850nm.
[0038] Fig.10 This is the MTF curve of the lens in Example 2 at a wavelength of 940nm.
[0039] Fig.11 This is a field curvature distortion diagram of the lens in Example 2 at a wavelength of 850nm.
[0040] Fig.12 This is a field curvature distortion diagram of the lens in Example 2 at a wavelength of 940nm.
[0041] Fig.13 This is the star point diagram of the lens in Example 2 at a wavelength of 850nm.
[0042] Fig.14 This is a relative illumination diagram of the lens in Example 2 at a wavelength of 850nm.
[0043] Fig.15 This is a structural diagram of the optical system of the lens in Example 3.
[0044] Fig.16 This is the MTF curve of the lens in Example 3 at a wavelength of 850nm.
[0045] Fig.17 This is the MTF curve of the lens in Example 3 at a wavelength of 940nm.
[0046] Fig.18 This is a field curvature distortion diagram of the lens in Example 3 at a wavelength of 850nm.
[0047] Fig.19 This is a field curvature distortion diagram of the lens in Example 3 at a wavelength of 940nm.
[0048] Fig. 20 This is the star point diagram of the lens in Example 3 at a wavelength of 850nm.
[0049] Fig.21 This is a relative illumination diagram of the lens in Example 3 at a wavelength of 850nm. Fig. 22 This is a structural diagram of the optical system of the lens in Example 4.
[0050] Fig.23 This is the MTF curve of the lens in Example 4 at a wavelength of 850nm.
[0051] Fig.24 This is the MTF curve of the lens in Example 4 at a wavelength of 940nm.
[0052] Fig.25 This is a field curvature distortion diagram of the lens in Example 4 at a wavelength of 850nm.
[0053] Fig.26 This is a field curvature distortion diagram of the lens in Example 4 at a wavelength of 940nm.
[0054] Fig. 27 This is the star point diagram of the lens in Example 4 at a wavelength of 850nm.
[0055] Fig.28 This is a relative illumination diagram of the lens in Example 4 at a wavelength of 850nm.
[0056] The above drawings include the following reference numerals:
[0057] 1. First lens; 2. Second lens; 3. Third lens; 4. Fourth lens; 5. Fifth lens; 6. Sixth lens; 7. Aperture; 8. Protective glass. DETAILED DESCRIPTION
[0058] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention. In addition, the technical features involved in each embodiment of the present invention described below can be combined with each other as long as they do not conflict with each other.
[0059] Reference Figures 1 to 28 As shown, a wide-angle TOF optical imaging lens comprises a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5 and a sixth lens 6 which are arranged in sequence along the optical axis from the object side to the image side, an aperture 7 is arranged between the third lens 3 and the fourth lens 4, a protective glass 8 is provided on the image side of the sixth lens 6, and the image side surface of the fifth lens 5 and the object side surface of the sixth lens 6 are glued to each other. Wherein: the first lens 1 has a negative refractive power, the object side surface of the first lens 1 is a convex surface, and the image side surface of the first lens 1 is a concave surface; the second lens 2 has a negative refractive power, the object side surface of the second lens 2 is a convex surface, and the image side surface of the second lens 2 is a concave surface; the third lens 3 has a positive refractive power, the object side surface of the third lens 3 is a convex surface, and the image side surface of the third lens 3 is a concave surface; the fourth lens 4 has a positive refractive power, the object side surface of the fourth lens 4 is a concave surface, and the image side surface of the fourth lens 4 is a convex surface; the fifth lens 5 has a positive refractive power, the object side surface of the fifth lens 5 is a convex surface, and the image side surface of the fifth lens 5 is a convex surface; the sixth lens 6 has a positive refractive power, the object side surface of the sixth lens 6 is a concave surface, and the image side surface of the sixth lens 6 is a concave surface.
[0060] The beneficial effects of this embodiment are: by reasonably allocating the diopter of each lens, optimizing the surface shape of each lens, etc., the imaging surface size of the optical system is increased on the basis of keeping the pixel size unchanged, a 1 / 2 inch CCD is selected, and the imaging surface diameter of the optical system is set to 8 mm.
[0061] Furthermore, the absolute value of the ratio of the focal length f1 of the first lens 1 to the total focal length f of the imaging lens of the optical system satisfies the following relationship: 3<|(f1 / f)|<7;
[0062] The absolute value of the ratio of the focal length f2 of the second lens 2 to the total focal length f of the optical system imaging lens satisfies the following relationship: 1.7<|(f2 / f)|<5;
[0063] The absolute value of the ratio of the focal length f3 of the third lens 3 to the total focal length f of the imaging lens of the optical system satisfies the following relationship: 0.5<|(f3 / f)|<2;
[0064] The absolute value of the ratio of the focal length f4 of the fourth lens 4 to the total focal length f of the imaging lens of the optical system satisfies the following relationship: 2<|(f4 / f)|<5;
[0065] The absolute value of the ratio of the focal length f5 of the fifth lens 5 to the total focal length f of the imaging lens of the optical system satisfies the following relationship: 0.2<|(f5 / f)|<2;
[0066] The absolute value of the ratio of the focal length f6 of the sixth lens 6 to the total focal length f of the imaging lens of the optical system satisfies the following relationship: 0.3<|(f6 / f)|<2.5.
[0067] The beneficial effect of this embodiment is: by reasonably allocating the focal length of each lens, the optical performance of the lens is improved. Specifically, in the first embodiment, f=6.9 mm; in the second embodiment, f=6.9 mm; in the third embodiment, f=6.7 mm; in the fourth embodiment, f=6.9 mm.
[0068] Furthermore, the lens satisfies the following relationship: 0.8<Y / f<1.4, wherein f is the total focal length of the optical system imaging lens, and Y is the diameter of the optical system imaging surface.
[0069] The beneficial effects of this embodiment are: a larger sensor size means higher resolution, better dynamic range and less image noise. By satisfying the above formula, the lens can be adapted to a larger sensor size, thereby capturing high-quality images. Specifically, in the first embodiment, Y / f=1.17; in the second embodiment, Y / f=1.21; in the third embodiment, Y / f=1.21; in the fourth embodiment, Y / f=1.16.
[0070] Furthermore, the lens satisfies the following relationship: 2.5<TTL / f<4.5, wherein TTL is the distance from the first lens 1 to the imaging surface on the optical axis, and f is the total focal length of the imaging lens of the optical system.
[0071] The beneficial effect of this embodiment is that satisfying the above formula can more effectively shorten the system length and realize the miniaturized optical system design. Specifically, in the first embodiment, TTL / f=3.61; in the second embodiment, TTL / f=3.66; in the third embodiment, TTL / f=3.7; in the fourth embodiment, TTL / f=3.59.
[0072] Furthermore, the second lens 2 and the sixth lens 6 are made of glass material with positive Dn / Dt.
[0073] The beneficial effects of this embodiment are as follows: satisfying the above formula can reduce the temperature drift of the entire lens optical system, and the temperature drift variation produced by the base and the remaining lenses is compensated by the second lens 2 and the sixth lens 6, thereby enhancing stable imaging at high and low temperatures of -40 to +85°C and reducing the amount of defocus.
[0074] Furthermore, the lens satisfies the following relationship: 40<R32<130, wherein R32 is the curvature radius of the image side surface of the third lens 3 .
[0075] The beneficial effect of this embodiment is that negative distortion is generated by the third lens 3 and is used to supplement the positive distortion generated by other lenses in the system, thereby greatly reducing the total distortion of the system.
[0076] Furthermore, the lens satisfies the following relationship: 5<FOV / Y<10, wherein FOV is the field of view angle corresponding to the diameter of the diagonal imaging surface of the sensor, and Y is the diameter of the diagonal imaging surface of the sensor.
[0077] The beneficial effect of this embodiment is: by controlling the field of view angle corresponding to the diagonal imaging surface of the sensor to 64.1°, the distortion of the optical system is controlled at the same time to meet the actual field of view angle requirements. Specifically, in the first embodiment, FOV / Y=7.72; in the second embodiment, FOV / Y=7.96; in the third embodiment, FOV / Y=7.97; in the fourth embodiment, FOV / Y=7.79.
[0078] Furthermore, the lens satisfies the following relationship: 3<|KR1 / KR2|<4, wherein KR1 and KR2 are Conic coefficients of the object side and image side of the fourth lens, respectively.
[0079] The beneficial effects of this embodiment are as follows: the fourth lens 4 is a glass aspherical surface, and by using a shared existing aspherical lens, there is no need to increase the inventory list, and by consuming the existing inventory, the production cost of the lens is reduced.
[0080] Furthermore, the lens edges and the entire plane steps of the first lens 1 to the sixth lens 6 are all coated with a black layer.
[0081] The beneficial effects of this embodiment are as follows: by applying black coating to the edges of each lens and the entire plane step, the reflection of stray light in the edge area of the lens is reduced, and similarly, the spacers between the lenses are anodized and blackened to reduce the reflection of stray light on the surface of the spacers, thereby avoiding the influence of stray light on the imaging quality.
[0082] Furthermore, the relative price coefficient of the first lens 1 is less than 30, the relative price coefficient of the second lens 2 is less than 60, and the relative price coefficient of the sixth lens 6 is less than 35.
[0083] The beneficial effect of this embodiment is: by restricting the price range of the first lens 1, the second lens 2 and the sixth lens 6, the production cost of the lens is reduced. Wherein, relative price = (selected glass price / H-K9L) × 10, H-K9L is the existing glass model.
[0084] On the other hand, the utility model provides a TOF optical imaging module, comprising a wide-angle TOF optical imaging lens as described in any of the above items and an 850nm photoelectric sensor or a 940nm photoelectric sensor.
[0085] The present invention will be described in more detail below in conjunction with Tables 1 to 4. It should be noted that the following tables are only specific embodiments of the present invention, rather than limiting examples.
[0086] Table 1 is a specific arrangement table of parameters such as the curvature radius, thickness interval, etc. of each lens in Example 1.
[0087]
[0088] Table 2 is a specific arrangement table of parameters such as the curvature radius, thickness interval, etc. of each lens in Example 2.
[0089]
[0090] Table 3 is a specific arrangement table of parameters such as the curvature radius, thickness interval, etc. of each lens in Example 3.
[0091]
[0092] Table 4 is a specific arrangement table of parameters such as the curvature radius, thickness interval, etc. of each lens in Example 4.
[0093]
[0094] The following is an explanation of the various figures:
[0095] Figure 2 This is the MTF curve of the lens in Example 1 at a wavelength of 850nm. The horizontal axis is the frequency, the unit is line pairs; the vertical axis is the MTF value, the unit is none. It can be seen from the figure that the MTF of the center field of view is greater than 0.5 at 50lp / mm, the MTF of the 0.6 field of view is greater than 0.4 at 50lp / mm, and the MTF of the full field of view is greater than 0.4 at 50lp / mm. The figure shows that the resolution of the optical system is relatively good, and it can basically meet the actual use requirements when equipped with a 300,000-pixel 1 / 2.0-inch near-infrared sensor.
[0096] Figure 3This is the MTF curve of the lens in Example 1 at a wavelength of 940nm. The horizontal axis is the frequency, the unit is line pairs; the vertical axis is the MTF value, the unit is none. It can be seen from the figure that the MTF of the center field of view is greater than 0.6 at 50lp / mm, the MTF of the 0.6 field of view is greater than 0.28 at 50lp / mm, and the MTF of the full field of view is greater than 0.28 at 50lp / mm. The figure shows that the resolution of the optical system is relatively good, and it can basically meet the actual use requirements when equipped with a 300,000-pixel 1 / 2.0-inch near-infrared sensor.
[0097] Figure 4 It is the field curvature distortion diagram of the lens in Example 1 at a wavelength of 850nm. Among them, the left figure is the 850nm spectrum field curvature diagram, the horizontal axis is the field curvature value, the unit is millimeter; the vertical axis is the normalized field of view, the unit is infinite rigid. It can be seen from the left figure: the field curvature of the TOF imaging lens of the utility model is within 0.1mm, the distance between the meridian light and the sagittal light is the farthest at around 0.8F field of view, and the maximum astigmatism is about 0.1mm. The astigmatism in the full field of view is about 0.08mm. The right figure is the F-Tan (Thete) optical distortion diagram, the horizontal axis is the percentage relative optical distortion value, the unit is %; the vertical axis is the normalized field of view, the unit is infinite rigid. It can be seen from the right figure: the F-Tan (Thete) optical distortion of the lens is within -4%, the degree of deformation is not large, and it can be corrected to a distortion-free image through simple image processing, which meets the actual use requirements.
[0098] Figure 5 It is the field curvature distortion diagram of the lens in Example 1 at a wavelength of 940nm. Among them, the left figure is the 940nm spectrum field curvature diagram, the horizontal axis is the field curvature value, the unit is millimeter; the vertical axis is the normalized field of view, the unit is infinite rigid. It can be seen from the left figure: the field curvature of the TOF imaging lens is within 0.1mm, the distance between the meridian light and the sagittal light is the farthest at around 0.8F field of view, and the maximum astigmatism is about 0.1mm. The astigmatism in the full field of view is about 0.08mm. The right figure is the F-Tan (Thete) optical distortion diagram, the horizontal axis is the percentage relative optical distortion value, the unit is %; the vertical axis is the normalized field of view, the unit is infinite rigid. It can be seen from the right figure: the F-Tan (Thete) optical distortion of the lens is within -4%, the degree of deformation is not large, and it can be corrected to a distortion-free image through simple image processing, which meets the actual use requirements.
[0099] Figure 6 This is the star point diagram of the lens at a wavelength of 850nm in Example 1. It can be seen from the figure that the maximum RMS root mean square radius is 22.514um and the maximum geometric spot radius is 98.954um. The star point spot size is about the sensor pixel size, which can meet the actual use requirements.
[0100] Figure 7 This is the relative illumination diagram of the lens in Example 1 at a wavelength of 850nm. The relative illumination diagram is the illumination ratio of each field of view to the central field of view, where the horizontal axis is the image plane half-image height in the Y direction, in mm, and the maximum field of view half-image height is 4mm. The vertical axis is the relative illumination value, in dimensionless units. It can be seen from the figure that the edge relative illumination of the optical system is greater than 70%, which can greatly avoid the dark corners around the image, and avoid the phenomenon of bright center area and dark corners at the edges, which improves the illumination performance of the lens 1.0F field of view, making the overall image brightness relatively coordinated.
[0101] Fig. 9 This is the MTF curve of the lens in Example 2 at a wavelength of 850nm. The horizontal axis is the frequency in line pairs; the vertical axis is the MTF value in units of none. It can be seen from the figure that the MTF of the center field of view is greater than 0.5 at 50lp / mm, the MTF of the 0.6 field of view is greater than 0.4 at 50lp / mm, and the MTF of the full field of view is greater than 0.4 at 50lp / mm. The figure shows that the resolution of the optical system is relatively good, and it can basically meet the actual use requirements when equipped with a 300,000-pixel 1 / 2.0-inch near-infrared sensor.
[0102] Fig.10 This is the MTF curve of the lens in Example 2 at a wavelength of 940nm. The horizontal axis is the frequency, the unit is line pair; the vertical axis is the MTF value, the unit is none. It can be seen from the figure: the MTF of the center field of view is greater than 0.6 at 50lp / mm, the MTF of the 0.6 field of view is greater than 0.2 at 50lp / mm, and the MTF of the full field of view is greater than 0.2 at 50lp / mm. The figure shows that the resolution of the optical system is relatively good, and it can basically meet the actual use requirements when equipped with a 300,000-pixel 1 / 2.0-inch near-infrared sensor.
[0103] Fig.11 It is the field curvature distortion diagram of the lens in Example 2 at a wavelength of 850nm. Among them, the left figure is the 850nm spectrum field curvature diagram, the horizontal axis is the field curvature value, the unit is millimeter; the vertical axis is the normalized field of view, the unit is infinite rigid. It can be seen from the left figure: the field curvature of the TOF imaging lens of the utility model is within 0.1mm, the distance between the meridian light and the sagittal light is the farthest at about 0.8F field of view, and the maximum astigmatism is about 0.1mm. The astigmatism in the full field of view is about 0.08mm. The right figure is the F-Tan (Thete) optical distortion diagram, the horizontal axis is the percentage relative optical distortion value, the unit is %; the vertical axis is the normalized field of view, the unit is infinite rigid. It can be seen from the right figure: the F-Tan (Thete) optical distortion of the lens is within -5%, the degree of deformation is not large, and it can be corrected to a distortion-free image through simple image processing, which meets the actual use requirements.
[0104] Fig.12 It is the field curvature distortion diagram of the lens in Example 2 at a wavelength of 940nm. Among them, the left figure is the 940nm spectrum field curvature diagram, the horizontal axis is the field curvature value, the unit is millimeter; the vertical axis is the normalized field of view, the unit is infinite rigid. It can be seen from the left figure: the field curvature of the TOF imaging lens is within 0.1mm, the distance between the meridian light and the sagittal light is the farthest at around 0.8F field of view, and the maximum astigmatism is about 0.1mm. The astigmatism in the full field of view is about 0.08mm. The right figure is the F-Tan (Thete) optical distortion diagram, the horizontal axis is the percentage relative optical distortion value, the unit is %; the vertical axis is the normalized field of view, the unit is infinite rigid. It can be seen from the right figure: the F-Tan (Thete) optical distortion of the lens is within -5%, the degree of deformation is not large, and it can be corrected to a distortion-free image through simple image processing, which meets the actual use requirements.
[0105] Fig.13 This is the star point diagram of the lens at a wavelength of 850nm in Example 2. It can be seen from the figure that the maximum RMS root mean square radius is 24.534um and the maximum geometric spot radius is 77.251um. The star point spot size is about the sensor pixel size, which can meet the actual use requirements.
[0106] Fig.14 This is the relative illumination diagram of the lens in Example 2 at a wavelength of 850nm. The relative illumination diagram is the illumination ratio of each field of view to the central field of view, where the horizontal axis is the image plane half-image height in the Y direction, in mm, and the maximum field of view half-image height is 4mm. The vertical axis is the relative illumination value, in dimensionless units. It can be seen from the figure that the edge relative illumination of the optical system is greater than 70%, which can greatly avoid the dark corners around the image, and avoid the phenomenon of bright center area and dark corners at the edge, which improves the illumination performance of the lens 1.0F field of view, making the overall image brightness relatively coordinated.
[0107] Fig.16 This is the MTF curve of the lens in Example 3 at a wavelength of 850nm. The horizontal axis is the frequency, the unit is line pairs; the vertical axis is the MTF value, the unit is none. It can be seen from the figure that the MTF of the center field of view is greater than 0.5 at 50lp / mm, the MTF of the 0.6 field of view is greater than 0.4 at 50lp / mm, and the MTF of the full field of view is greater than 0.4 at 50lp / mm. The figure shows that the resolution of the optical system is relatively good, and it can basically meet the actual use requirements when equipped with a 300,000-pixel 1 / 2.0-inch near-infrared sensor.
[0108] Fig.17This is the MTF curve of the lens in Example 3 at a wavelength of 940nm. The horizontal axis is the frequency, the unit is line pairs; the vertical axis is the MTF value, the unit is none. It can be seen from the figure: the MTF of the center field of view is greater than 0.6 at 50lp / mm, the MTF of the 0.6 field of view is greater than 0.25 at 50lp / mm, and the MTF of the full field of view is greater than 0.25 at 50lp / mm. The figure shows that the resolution of the optical system is relatively good, and it can basically meet the actual use requirements when equipped with a 300,000-pixel 1 / 2.0-inch near-infrared sensor.
[0109] Fig.18 It is the field curvature distortion diagram of the lens in Example 3 at a wavelength of 850nm. Among them, the left figure is the 850nm spectrum field curvature diagram, the horizontal axis is the field curvature value, the unit is millimeter; the vertical axis is the normalized field of view, the unit is infinite rigid. It can be seen from the left figure: the field curvature of the TOF imaging lens of the utility model is within 0.1mm, the distance between the meridian light and the sagittal light is the farthest at about 0.8F field of view, and the maximum astigmatism is about 0.1mm. The astigmatism in the full field of view is about 0.08mm. The right figure is the F-Tan (Thete) optical distortion diagram, the horizontal axis is the percentage relative optical distortion value, the unit is %; the vertical axis is the normalized field of view, the unit is infinite rigid. It can be seen from the right figure: the F-Tan (Thete) optical distortion of the lens is within -5%, the degree of deformation is not large, and it can be corrected to a distortion-free image through simple image processing, which meets the actual use requirements.
[0110] Fig.19 It is the field curvature distortion diagram of the lens in Example 3 at a wavelength of 940nm. Among them, the left figure is the 940nm spectrum field curvature diagram, the horizontal axis is the field curvature value, the unit is millimeter; the vertical axis is the normalized field of view, the unit is infinite rigid. It can be seen from the left figure: the field curvature of the TOF imaging lens is within 0.1mm, the distance between the meridian light and the sagittal light is the farthest at around 0.8F field of view, and the maximum astigmatism is about 0.1mm. The astigmatism in the full field of view is about 0.08mm. The right figure is the F-Tan (Thete) optical distortion diagram, the horizontal axis is the percentage relative optical distortion value, the unit is %; the vertical axis is the normalized field of view, the unit is infinite rigid. It can be seen from the right figure: the F-Tan (Thete) optical distortion of the lens is within -5%, the degree of deformation is not large, and it can be corrected to a distortion-free image through simple image processing, which meets the actual use requirements.
[0111] Fig. 20 This is the star point diagram of the lens at a wavelength of 850nm in Example 3. It can be seen from the figure that the maximum RMS root mean square radius is 24.094 and the maximum geometric spot radius is 74.676um. The star point spot size is about the sensor pixel size, which can meet the actual use requirements.
[0112] Fig.21 This is the relative illumination diagram of the lens in Example 3 at a wavelength of 850nm. The relative illumination diagram is the illumination ratio of each field of view to the central field of view, where the horizontal axis is the image plane half-image height in the Y direction, in mm, and the maximum field of view half-image height is 4mm. The vertical axis is the relative illumination value, in dimensionless units. It can be seen from the diagram that the edge relative illumination of the optical system is greater than 70%, which can greatly avoid the dark corners around the image, and avoid the phenomenon of bright center area and dark corners at the edges, which improves the illumination performance of the lens 1.0F field of view, making the overall image brightness relatively coordinated.
[0113] Fig.23 This is the MTF curve of the lens in Example 4 at a wavelength of 850nm. The horizontal axis is the frequency in line pairs; the vertical axis is the MTF value in units of none. It can be seen from the figure that the MTF of the center field of view is greater than 0.5 at 50lp / mm, the MTF of the 0.6 field of view is greater than 0.35 at 50lp / mm, and the MTF of the full field of view is greater than 0.35 at 50lp / mm. The figure shows that the resolution of the optical system is relatively good, and it can basically meet the actual use requirements when equipped with a 300,000-pixel 1 / 2.0-inch near-infrared sensor.
[0114] Fig.24 This is the MTF curve of the lens in Example 4 at a wavelength of 940nm. The horizontal axis is the frequency, the unit is line pairs; the vertical axis is the MTF value, the unit is none. It can be seen from the figure that the MTF of the center field of view is greater than 0.6 at 50lp / mm, the MTF of the 0.6 field of view is greater than 0.2 at 50lp / mm, and the MTF of the full field of view is greater than 0.2 at 50lp / mm. The figure shows that the resolution of the optical system is relatively good, and it can basically meet the actual use requirements when equipped with a 300,000-pixel 1 / 2.0-inch near-infrared sensor.
[0115] Fig.25 It is the field curvature distortion diagram of the lens in Example 4 at a wavelength of 850nm. Among them, the left figure is the 850nm spectrum field curvature diagram, the horizontal axis is the field curvature value, the unit is millimeter; the vertical axis is the normalized field of view, the unit is infinite rigid. It can be seen from the left figure: the field curvature of the TOF imaging lens of the utility model is within 0.1mm, the distance between the meridian light and the sagittal light is the farthest at around 0.8F field of view, and the maximum astigmatism is about 0.1mm. The astigmatism in the full field of view is about 0.08mm. The right figure is the F-Tan (Thete) optical distortion diagram, the horizontal axis is the percentage relative optical distortion value, the unit is %; the vertical axis is the normalized field of view, the unit is infinite rigid. It can be seen from the right figure: the F-Tan (Thete) optical distortion of the lens is within -5%, the degree of deformation is not large, and it can be corrected to a distortion-free image through simple image processing, which meets the actual use requirements.
[0116] Fig.26 This is the field curvature distortion diagram of the lens in Example 4 at a wavelength of 940nm. Among them, the left figure is the 940nm spectrum field curvature diagram, the horizontal axis is the field curvature value, the unit is millimeter; the vertical axis is the normalized field of view, the unit is infinite rigid. It can be seen from the left figure: the field curvature of the TOF imaging lens is within 0.1mm, the distance between the meridian light and the sagittal light is the farthest at around 0.8F field of view, and the maximum astigmatism is about 0.1mm. The astigmatism in the full field of view is about 0.08mm. The right figure is the F-Tan (Thete) optical distortion diagram, the horizontal axis is the percentage relative optical distortion value, the unit is %; the vertical axis is the normalized field of view, the unit is infinite rigid. It can be seen from the right figure: the F-Tan (Thete) optical distortion of the lens is within -4%, the degree of deformation is not large, and it can be corrected to a distortion-free image through simple image processing, which meets the actual use requirements.
[0117] Fig. 27 This is the star point diagram of the lens at a wavelength of 850nm in Example 4. It can be seen from the figure that the maximum RMS root mean square radius is 24.625 and the maximum geometric spot radius is 79.180um. The star point spot size is about the sensor pixel size, which can meet the actual use requirements.
[0118] Fig.28 This is the relative illumination diagram of the lens in Example 4 at a wavelength of 850nm. The relative illumination diagram is the illumination ratio of each field of view to the central field of view, where the horizontal axis is the image plane half-image height in the Y direction, in mm, and the maximum field of view half-image height is 4mm. The vertical axis is the relative illumination value, in dimensionless units. It can be seen from the figure that the edge relative illumination of the optical system is greater than 70%, which can greatly avoid the dark corners around the image, and avoid the phenomenon of bright center area and dark corners at the edge, which improves the illumination performance of the lens 1.0F field of view, making the overall image brightness relatively coordinated.
[0119] In summary, the beneficial effects of the utility model are: First, on the basis of keeping the pixel size unchanged, the size of the imaging surface of the optical system is increased, a 1 / 2-inch CCD is selected, and the imaging surface diameter of the optical system is set to 8mm. Second, the sensitivity is optimized to improve the production yield of the lens. Third, relatively cheap materials are used to share mass-produced lenses to reduce the material cost of the lens. Fourth, the introduction of temperature drift athermal design improves the actual applicable environment of the lens, and it can still maintain normal clarity without losing focus under harsh temperature conditions. Fifth, a matte treatment process is added, and the edges of the entire plane of the lens are blackened to avoid the reduction of resolution when other light sources interfere. Sixth, by controlling the field of view angle corresponding to the diagonal imaging surface of the sensor to 64.1°, the distortion of the optical system is controlled at the same time to meet the actual field of view angle requirements. Seventh, by reducing the distortion contribution of the object image surface of the first lens and the second lens and increasing the distortion contribution of the image side of the third lens, the total optical distortion of the system is reduced.
Claims
1. A wide-angle TOF optical imaging lens, characterized in that: The method comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens which are arranged in sequence along the optical axis from the object side to the image side, wherein: The first lens has a negative refractive power, the object side surface of the first lens is a convex surface, and the image side surface of the first lens is a concave surface; The second lens has a negative refractive power, the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a concave surface; The third lens has positive refractive power, the object side surface of the third lens is convex, and the image side surface of the third lens is concave; The fourth lens has positive refractive power, the object side surface of the fourth lens is a concave surface, and the image side surface of the fourth lens is a convex surface; The fifth lens has positive refractive power, the object side surface of the fifth lens is convex, and the image side surface of the fifth lens is convex; The sixth lens has positive refractive power, the object side surface of the sixth lens is a concave surface, and the image side surface of the sixth lens is a concave surface.
2. The wide-angle TOF optical imaging lens according to claim 1, characterized in that: The absolute value of the ratio of the focal length f1 of the first lens to the total focal length f of the imaging lens of the optical system satisfies the following relationship: 3<|(f1 / f)|<7; The absolute value of the ratio of the focal length f2 of the second lens to the total focal length f of the imaging lens of the optical system satisfies the following relationship: 1.7<|(f2 / f)|<5; The absolute value of the ratio of the focal length f3 of the third lens to the total focal length f of the imaging lens of the optical system satisfies the following relationship: 0.5<|(f3 / f)|<2; The absolute value of the ratio of the focal length f4 of the fourth lens to the total focal length f of the imaging lens of the optical system satisfies the following relationship: 2<|(f4 / f)|<5; The absolute value of the ratio of the focal length f5 of the fifth lens to the total focal length f of the imaging lens of the optical system satisfies the following relationship: 0.2<|(f5 / f)|<2; The absolute value of the ratio of the focal length f6 of the sixth lens to the total focal length f of the imaging lens of the optical system satisfies the following relationship: 0.3<|(f6 / f)|<2.
5.
3. The wide-angle TOF optical imaging lens according to claim 1, characterized in that: The lens satisfies the following relationship: 0.8<Y / f<1.4, wherein f is the total focal length of the optical system imaging lens, and Y is the diameter of the optical system imaging surface.
4. The wide-angle TOF optical imaging lens according to claim 1, characterized in that: The lens satisfies the following relationship: 2.5<TTL / f<4.5, wherein TTL is the distance from the first lens to the imaging surface on the optical axis, and f is the total focal length of the imaging lens of the optical system.
5. The wide-angle TOF optical imaging lens according to claim 1, characterized in that: The second lens and the sixth lens are made of glass material with positive Dn / Dt.
6. The wide-angle TOF optical imaging lens according to claim 1, characterized in that: The lens satisfies the following relationship: 40<R32<130, wherein R32 is the radius of curvature of the image side surface of the third lens.
7. The wide-angle TOF optical imaging lens according to claim 1, characterized in that: The lens satisfies the following relationship: 5<FOV / Y<10, wherein FOV is the field of view angle corresponding to the diameter of the diagonal imaging surface of the sensor, and Y is the diameter of the diagonal imaging surface of the sensor.
8. The wide-angle TOF optical imaging lens according to claim 1, characterized in that: The lens satisfies the following relationship: 3<|KR1 / KR2|<4, wherein KR1 and KR2 are the Conic coefficients of the object side and image side of the fourth lens, respectively.
9. The wide-angle TOF optical imaging lens according to claim 1, characterized in that: The lens edges and the entire plane steps of the first to sixth lenses are all coated with a black layer.
10. A TOF optical imaging module, characterized in that: The invention comprises the wide-angle TOF optical imaging lens as claimed in any one of claims 1 to 9 and an 850nm photoelectric sensor or a 940nm photoelectric sensor.