Continuous zooming optical system with visible light and near-infrared laser sharing aperture and light path

Abstract

The embodiment of the invention discloses a visible light and near-infrared laser common-aperture common-path continuous zooming optical system. The optical system comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens, a tenth lens, an eleventh lens and a twelfth lens which are sequentially arranged on the same optical axis from the object side to the image side, wherein all the lenses are made of optical glass or optical crystal materials. According to the invention, a dual-band common-path zooming form is adopted, and the visible light band and the near-infrared band are zoomed and imaged at the same time. According to the dual-band common-path continuous zooming optical system provided by the embodiment of the invention, a spectroscope and a compensation lens group are not used, and imaging is performed on the same focal plane, so that the size of the optical system is further reduced, the weight of the system is reduced, the complexity and the assembly difficulty of the system are further reduced, and the cost is also reduced.

Description

Technical Field

[0001] The invention relates to a dual-band common optical path continuous zoom optical system, in particular to a continuous zoom optical system with common aperture and common optical path for visible light (486nm-656nm) and near-infrared laser (1060nm). Background Art

[0002] For long-distance observation and aiming optical systems, there are needs for target search and detailed observation. The zoom system is an optical system that can change the focal length while maintaining the stability of the image plane and stable imaging. Therefore, compared with the fixed-focus optical system, the continuous zoom system can change the observation magnification when observing at the same position to meet the above needs. In addition to being used for photography in daily life, the continuous zoom system is also widely used in national defense construction.

[0003] For optical systems, different bands contain different information. For example, visible light can be received by the human eye and is easy to observe, while the infrared band has good dust and smoke penetration capabilities, is not limited by day or night, and has good concealment. For different purposes and usage scenarios, it is necessary to design an optical system that responds to specific bands.

[0004] Laser is a commonly used target marking method due to its collimation. Due to different demand scenarios, near-infrared lasers that are invisible to the human eye are sometimes used as marking methods. In order to detect whether the laser marking is accurate, a detection device is needed that can observe both the target and the near-infrared laser spot.

[0005] In this context, the simplest solution is to design the zoom system separately in different bands, and then form a dual-band system together. Specifically, the system has a visible light continuous zoom system and a continuous zoom system for the band where the near-infrared laser is located. However, this solution will cause the entire optical system to be bulky. A further solution is to merge part of the optical paths of the visible light and near-infrared laser bands into one channel, and through a set of lenses, the visible light and near-infrared laser can be continuously zoomed at the same time. Through the above measures, the volume of the system is greatly reduced, and it can be presented in two bands at the same time, and the projected laser spot can be observed while observing the target. However, the above dual-band common optical path system needs to add a beam splitter and a compensation mirror group in the optical system to ensure image reception and imaging effects. Therefore, the integration needs to be further improved, especially the beam splitter and the beam splitting optical path. Their volume and weight are not conducive to the overall lightweight and compactness of the system. Summary of the invention

[0006] In order to solve the deficiencies in the above-mentioned prior art, the present invention provides a continuous zoom optical system with a common aperture and a common optical path for two bands of visible light and near-infrared laser. The optical system can simultaneously receive light from two bands of visible light and near-infrared laser, and zoom and image at the same time.

[0007] In order to achieve the above object, the specific technical solution of the present invention is:

[0008] A continuous zoom optical system with common aperture and common optical path for visible light and near-infrared laser, characterized in that the optical system consists of a front fixed group, a magnification group, a compensation group and a rear fixed group arranged in sequence from the object side to the image side along the optical axis, and the visible light band and the near-infrared band are imaged through the same optical path and the same focal plane.

[0009] Furthermore, the front fixed group is composed of a first lens E1 and a second lens E2 arranged in sequence along the optical axis, and has positive optical power; wherein the first lens E1 is a double cemented lens, composed of a negative meniscus lens close to the object side and a double convex lens close to the image side, and the double convex lens uses an ultra-low dispersion material; the second lens E2 is a positive meniscus lens.

[0010] Furthermore, the zoom group is composed of a third lens E3 and a fourth lens E4 which are sequentially arranged along the optical axis and have negative optical power; the third lens E3 is a cemented lens, which is composed of a double convex lens close to the object side and a double concave lens close to the image side; and the fourth lens E4 is a double concave lens.

[0011] Furthermore, the compensation group is composed of a fifth lens E5 arranged along the optical axis and has negative optical power; the fifth lens E5 is a double cemented lens, composed of a positive meniscus lens close to the object side and a double concave lens close to the image side.

[0012] Further, the rear fixed group is composed of a sixth lens E6, a seventh lens E7, an eighth lens E8, a ninth lens E9, a tenth lens E10, an eleventh lens E11 and a twelfth lens E12 which are sequentially arranged along the optical axis and have positive optical power; the sixth lens E6 is a biconvex lens; the seventh lens E7 is a double cemented lens, which is composed of a positive biconvex lens close to the object side and a biconcave lens close to the image side; the eighth lens E8 is a positive meniscus lens, whose convex surface is close to the object side and whose concave surface is close to the image side; the ninth lens E9 is a negative meniscus lens; the tenth lens E10 is a negative meniscus lens; the eleventh lens E11 is a positive meniscus lens, whose concave surface is close to the object side and whose convex surface is close to the image side; and the twelfth lens E12 is a parallel plate.

[0013] Furthermore, the material of all lenses is optical glass or optical crystal material.

[0014] Furthermore, the twelfth lens E12 is selected to be a functional lens for realizing a filter and / or an attenuation plate according to the type of the selected detector.

[0015] Furthermore, the diameter of the selected detector is less than or equal to 8 mm.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] (1) The present invention adopts a zooming form with a common aperture and common optical path for all working bands. During the zooming process, the zoom group moves linearly and the compensation group moves nonlinearly. The visible light band and the near-infrared laser band zoom continuously at the same time. The focal length, magnification and field of view of the two bands keep changing synchronously, thus realizing the synchronous observation of the visible light band and the near-infrared laser band. The system has the advantages of a traditional dual-band common optical path optical system, that is, when information of different bands needs to be used, there is no need to switch the optical path. For a moving observation target, it can prevent the target from being lost due to switching the optical path.

[0018] (2) The present invention removes the beam splitter and compensation lens group included in the general dual-band optical system in the optical path, further reducing the volume of the optical system and the number of components of the optical system;

[0019] (3) The present invention integrates visible light and near-infrared laser bands into the same continuous zoom optical system by adopting the dual-band common aperture and common optical path method. By selecting materials and adjusting the structural form, compared with the traditional dual-band continuous zoom optical system, the present invention is different from the prior art in that it does not use a beam splitter or a compensation lens group, thereby further reducing the volume of the optical system, reducing the weight of the system, and reducing the complexity of the system. This greatly reduces the difficulty of assembling the system and also reduces the cost, which is of reference significance for the miniaturization of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] One or more embodiments are exemplarily described by pictures in the corresponding drawings, and these exemplified descriptions do not constitute limitations of the embodiments. Elements and steps with the same reference numerals in the drawings are represented as similar elements and steps. Unless otherwise specified, the figures in the drawings do not constitute proportional limitations.

[0021] Figure 1 A schematic diagram of the structure of a continuous zoom optical system with a common aperture and common optical path for visible light and near-infrared laser provided in one embodiment of the present invention; in the figure: E1-first lens, E2-second lens, E3-third lens, E4-fourth lens, E5-fifth lens, E6-sixth lens, E7-seventh lens, E8-eighth lens, E9-ninth lens, E10-tenth lens, E11-eleventh lens, E12-twelfth lens;

[0022] Figure 2 A schematic diagram of a lens surface of a continuous zoom optical system with a common aperture and a common optical path for visible light and near-infrared laser provided by an embodiment of the present invention;

[0023] Figure 3 for Figure 1 The MTF diagram of the continuous zoom optical system with the same aperture and optical path for visible light and near-infrared laser working in the visible light band at the telephoto position (focal length of 420mm);

[0024] Figure 4 for Figure 1 The MTF diagram of the continuous zoom optical system with the same aperture and optical path for visible light and near-infrared laser working in the visible light band at the mid-focus position (when the focal length is 250mm);

[0025] Figure 5 for Figure 1 The MTF diagram of the continuous zoom optical system with the same aperture and optical path for visible light and near-infrared laser working in the visible light band at a wide angle position (when the focal length is 95mm);

[0026] Figure 6 for Figure 1 The MTF diagram of the continuous zoom optical system with the same aperture and optical path for visible light and near-infrared laser working in the near-infrared band at the telephoto position (focal length of 420mm);

[0027] Figure 7 for Figure 1 The MTF diagram of the continuous zoom optical system with the same aperture and optical path for visible light and near-infrared laser working in the near-infrared band at the mid-focus position (focal length of 250mm);

[0028] Figure 8 for Figure 1 The MTF diagram of the continuous zoom optical system with the same aperture and optical path for visible light and near-infrared laser working in the near-infrared band at a wide angle position (when the focal length is 95mm);

[0029] Fig. 9 for Figure 1 The field curvature and distortion diagram of the continuous zoom optical system with the same aperture and optical path for visible light and near-infrared laser working in the visible light band at the telephoto position (focal length of 420mm);

[0030] Fig.10 for Figure 1 The field curvature and distortion diagram of the continuous zoom optical system with the same aperture and optical path for visible light and near-infrared laser working in the visible light band at the mid-focus position (when the focal length is 250mm);

[0031] Fig.11 for Figure 1The field curvature and distortion diagram of the continuous zoom optical system with the same aperture and optical path for visible light and near-infrared laser working in the visible light band at a wide angle position (when the focal length is 95mm);

[0032] Fig.12 for Figure 1 The field curvature and distortion diagram of the continuous zoom optical system with the same aperture and optical path for visible light and near-infrared laser working in the near-infrared band at the telephoto position (focal length of 420mm);

[0033] Fig.13 for Figure 1 The field curvature and distortion diagram of the continuous zoom optical system with the same aperture and optical path for visible light and near-infrared laser working in the near-infrared band at the mid-focus position (when the focal length is 250mm);

[0034] Fig.14 for Figure 1 The field curvature and distortion diagram of the continuous zoom optical system with the same aperture and optical path for visible light and near-infrared laser working in the near-infrared band at a wide-angle position (when the focal length is 95mm);

[0035] Fig.15 for Figure 1 The point diagram of the continuous zoom optical system with the same aperture and optical path for visible light and near-infrared laser working in the visible light band at the telephoto position (when the focal length is 420mm);

[0036] Fig.16 for Figure 1 The point diagram of the continuous zoom optical system with common aperture and common optical path for visible light and near-infrared laser working in the visible light band at the mid-focus position (when the focal length is 250mm);

[0037] Fig.17 for Figure 1 The point diagram of the continuous zoom optical system with the same aperture and optical path for visible light and near-infrared laser working in the visible light band at a wide angle position (when the focal length is 95mm);

[0038] Fig.18 for Figure 1 The point diagram of the continuous zoom optical system with the same aperture and optical path for visible light and near-infrared laser working in the near-infrared band at the telephoto position (when the focal length is 420mm);

[0039] Fig.19 for Figure 1 The point diagram of the continuous zoom optical system with the same aperture and optical path for visible light and near-infrared laser working in the near-infrared band at the mid-focus position (when the focal length is 250mm);

[0040] Fig. 20 for Figure 1The point diagram of the continuous zoom optical system with the same aperture and optical path for visible light and near-infrared laser working in the near-infrared light band at a wide angle position (when the focal length is 95 mm); DETAILED DESCRIPTION

[0041] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help the technical staff to further understand the present invention, but do not limit the present invention in any form. It should be particularly pointed out that for those of ordinary skill in the art, some variations and improvements can be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0042] In order to make the purpose, technical solution and features of the present application more clearly described, the present application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0043] In order to facilitate the definition of the connection structure, the present invention defines the position of the optical element with reference to the light emitting direction.

[0044] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used in this specification with respect to the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used in this specification includes any and all combinations of one or more of the related listed items.

[0045] Example 1

[0046] See also Figure 1 , shows a schematic structural diagram of a continuous zoom optical system with a common aperture and common optical path for visible light and near-infrared laser provided by an embodiment of the present invention, the optical system includes a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a sixth lens E6, a seventh lens E7, an eighth lens E8, a ninth lens E9, a tenth lens E10, an eleventh lens E11, and a twelfth lens E12, which are arranged in sequence along a common optical axis from the object side to the image side.

[0047] The first lens E1 is a doublet lens, which is composed of a negative meniscus lens near the object side and a double convex lens near the image side, and has positive refractive power.

[0048] The second lens E2 is a positive meniscus lens, with a convex surface close to the object side and a concave surface close to the image side, and has positive refractive power.

[0049] The first lens E1 and the second lens E2 together form a front fixed group of a continuous zoom optical system with a common aperture and a common optical path for visible light and near-infrared laser.

[0050] The third lens E3 is a double cemented lens, consisting of a double convex lens near the object side and a double concave lens near the image side, and has positive refractive power.

[0051] The fourth lens E4 is a biconcave lens.

[0052] The third lens E3 and the fourth lens E4 together form a zoom group of a continuous zoom optical system with a common aperture and a common optical path for visible light and near-infrared laser.

[0053] The fifth lens E5 is a double cemented lens, consisting of a positive meniscus lens near the image side and a double concave lens near the object side, with negative optical power, forming a compensation group of a continuous zoom optical system with a common aperture and optical path for visible light and near-infrared laser.

[0054] The sixth lens E6 is a biconvex lens with positive refractive power.

[0055] The seventh lens E7 is a double cemented lens, consisting of a double convex lens close to the object side and a double concave lens close to the image side, and has negative optical power.

[0056] The eighth lens E8 is a positive meniscus lens with a convex surface close to the object side and a concave surface close to the image side, and has positive refractive power.

[0057] The ninth lens E9 is a negative meniscus lens, with a convex surface close to the object side and a concave surface close to the image side, and has negative optical power.

[0058] The tenth lens E10 is a negative meniscus lens, with a convex surface close to the object side and a concave surface close to the image side, and has negative optical power.

[0059] The eleventh lens E11 is a positive meniscus lens with a concave surface close to the object side and a convex surface close to the image side, and has positive refractive power.

[0060] The twelfth lens E12 is a parallel flat plate, and according to the type of the selected detector, it serves as a filter and an attenuation plate.

[0061] In some other embodiments, the twelfth lens may be removed according to the characteristics of the detector, such as spectral response.

[0062] In some other embodiments, each cemented lens of the continuous zoom optical system with the same aperture and optical path for visible light and near-infrared laser can be converted into a double separated lens.

[0063] In the embodiments of the present invention, the lenses are made of optical glass, which is common, easily available and easy to process.

[0064] In some other embodiments, the lens materials of the continuous zoom optical system with the same aperture and optical path for visible light and near-infrared laser can be replaced with optical resin or optical crystal material according to specific needs.

[0065] Principle of the present invention:

[0066] The present invention is composed of a front fixed group, a zoom group, a compensation group and a rear fixed group. Its form is similar to that of a traditional single-band continuous zoom optical system, but it meets the technical requirements for imaging the visible light band and the near-infrared laser band at the same time, and realizes simultaneous zooming of the two bands. The present invention uses glass with good dispersion performance such as HFK61B in the front fixed group to reduce the chromatic aberration caused by the wide band. At the same time, multiple double-cemented lenses are used in the entire optical system to further correct the aberration. The present invention uses a cam to achieve continuous zooming, adopts the form of negative group compensation, has a zoom ratio of 4× (the design redundant zoom ratio is 4.4×), a short zoom stroke, and a zoom curve that is smooth and has no inflection point. In order to achieve lightweighting of the system, reduce system complexity, and reduce processing costs, the present invention does not use aspherical lenses or beam splitters, and all working bands are imaged simultaneously through the same optical path.

[0067] In the embodiment of the present invention, the surface parameters of the eyepiece lens are shown in Table 1 below.

[0068] Table 1

[0069]

[0070]

[0071] Wherein S14* is the aperture surface of the continuous zoom optical system, and D1, D2, and D3 are the intervals between the front fixed group, the variable magnification group, the compensation group, and the rear fixed group.

[0072] Table 2 shows the values ​​of D1, D2, and D3 at different focal lengths, which are used to illustrate the movement of the zoom group and the compensation group.

[0073] Table 2

[0074] Wide angle position 95 / mm Center focus position 250 / mm Telephoto position 420 / mm D1 3.55527095136798 62.5155740546312 83.2418687238451 D2 57.2135812557904 7.08590564592335 5.18971862636285 D3 32.6629463202292 23.8303188268331 5.00021117717958

[0075] In this embodiment, the radius of the detector is 4 mm and the pixel size is 8.6 μm.

[0076] In this embodiment, the working band is the visible light band (486nm~656nm), the near infrared band (1060nm)

[0077] In some other embodiments, the size of the image detector can be changed and the wavelength of the near-infrared band can be adjusted according to specific needs.

[0078] Next, the imaging quality of the continuous zoom optical system with the same aperture and optical path for the visible light and the near-infrared laser is tested.

[0079] Figure 3 to Figure 8 This is the MTF diagram of the continuous zoom optical system with visible light and near-infrared laser sharing the same aperture and optical path. MTF (Modulation Transfer Function) can reflect the imaging quality of the optical system. Specifically, the larger the area below the MTF curve and the x-axis, the smoother the transition of the MTF curve, and the better the imaging quality of the optical system. It can be seen from the figure that the MTF of the continuous zoom optical system with visible light and near-infrared laser sharing the same aperture and optical path is higher than 0.4 at its limit frequency of 60 line pairs / mm, indicating that the system has excellent imaging performance.

[0080] Figures 9 to 14 for Figure 1 From the field curvature and distortion diagram of the continuous zoom optical system with the same aperture and optical path for visible light and near-infrared laser, we can see that the axial aberration of the eyepiece optical system is not large. The field curvature is within the range of ±0.1mm, that is, the field curvature of the continuous zoom optical system with the same aperture and optical path for visible light and near-infrared laser has been corrected to a smaller range. At the same time, when the distortion of the system is less than 4%, the deformation of the imaging is not felt. It can be seen from the figure that the distortion of the system is less than 1%, and there is no distortion in the imaging that is easily noticeable to the naked eye.

[0081] Figures 15 to 20 for Figure 1 The point diagram of the continuous zoom optical system with common aperture and common optical path of visible light and near-infrared laser reflects the geometric structure of the imaging of the optical system. In the image quality evaluation, the density of the point diagram can be used to directly reflect the quality of the imaging. The smaller the RMS radius in the point diagram, the smaller the aberration, and the better the imaging quality of the system. It can be seen that within the RMS diameter of 9μm, the size of the spot radius of each field of view does not change much, the aberration correction is good, and the imaging quality of the continuous zoom optical system with common aperture and common optical path of visible light and near-infrared laser is excellent.

[0082] Finally, it is noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. On the basis of the present invention, the technical features in the above embodiments or different embodiments may also be combined, and the order of the steps is not limited. There are other changes in different aspects of the present invention as described above, which are not mentioned one by one in detail for the sake of simplicity. The description of the present invention is based on the aforementioned embodiments, and those skilled in the art should understand that we can still modify the technical solutions recorded in the above embodiments, or make equivalent replacements for some of the technical features therein, and these modifications or replacements should not essentially deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A continuous zoom optical system with common aperture and common optical path for visible light and near-infrared laser, characterized in that: The optical system consists of a front fixed group, a zoom group, a compensation group and a rear fixed group which are arranged in sequence from the object side to the image side along the optical axis. The visible light band and the near infrared band are imaged through the same optical path and confocal plane.

2. The continuous zoom optical system with common aperture and common optical path of visible light and near-infrared laser according to claim 1 is characterized by: The front fixed group is composed of a first lens (E1) and a second lens (E2) arranged in sequence along the optical axis, and has positive optical power; wherein the first lens (E1) is a double cemented lens, composed of a negative meniscus lens close to the object side and a double convex lens close to the image side, and the double convex lens is made of ultra-low dispersion material; the second lens (E2) is a positive meniscus lens.

3. The continuous zoom optical system with common aperture and common optical path of visible light and near-infrared laser according to claim 1, characterized in that: The zoom group is composed of a third lens (E3) and a fourth lens (E4) arranged in sequence along the optical axis, and has negative optical power; the third lens (E3) is a cemented lens, composed of a double convex lens close to the object side and a double concave lens close to the image side; the fourth lens (E4) is a double concave lens.

4. The continuous zoom optical system with common aperture and common optical path of visible light and near-infrared laser according to claim 1, characterized in that: The compensation group is composed of a fifth lens (E5) arranged along the optical axis and has negative optical power; the fifth lens (E5) is a double cemented lens, which is composed of a positive meniscus lens close to the object side and a double concave lens close to the object side.

5. The continuous zoom optical system with common aperture and common optical path of visible light and near-infrared laser according to claim 1, characterized in that: The rear fixed group is composed of a sixth lens (E6), a seventh lens (E7), an eighth lens (E8), a ninth lens (E9), a tenth lens (E10), an eleventh lens (E11) and a twelfth lens (E12) which are sequentially arranged along the optical axis and have positive optical power; the sixth lens (E6) is a biconvex lens; the seventh lens (E7) is a double cemented lens, which is composed of a biconvex lens close to the object side and a biconcave lens close to the image side; the eighth lens (E8) is a positive meniscus lens, whose convex surface is close to the object side and whose concave surface is close to the image side; the ninth lens (E9) is a negative meniscus lens; the tenth lens (E10) is a negative meniscus lens; the eleventh lens (E11) is a positive meniscus lens, whose concave surface is close to the object side and whose convex surface is close to the image side; and the twelfth lens (E12) is a parallel plate.

6. The continuous zoom optical system with common aperture and common optical path of visible light and near-infrared laser according to any one of claims 1 to 5, characterized in that: All lenses are made of optical glass or optical crystal materials.

7. The continuous zoom optical system with common aperture and common optical path of visible light and near-infrared laser according to any one of claims 1 to 5, characterized in that: The twelfth lens (E12) is selected according to the type of the selected detector to realize the function of a filter and / or an attenuation plate.

8. The continuous zoom optical system with common aperture and common optical path of visible light and near-infrared laser according to any one of claims 1 to 5, characterized in that: The selected detector diameter is less than or equal to 8mm.

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