A dual-band laser ranging optical structure

Abstract

The present invention relates to the technical field of space target laser ranging, and specifically provides a dual-band laser ranging optical structure. A dual-band ranging unit is arranged on the rear optical path of the first image plane of the Cassegrain system. The target beam is divided into visible light and short-wave infrared by a first beam splitter. The visible light is split by a second beam splitter into: a beam of 532 nm band light, and a beam of mixed light of 532 nm band and 600 nm - 900 nm band; which are respectively used for laser ranging, beam monitoring and detection imaging. The short-wave infrared is split by a third beam splitter into: a beam of 1064 nm band light, and a beam of mixed light of 1064 nm band and 1100 nm - 1700 nm band; which are respectively used for laser ranging, beam monitoring and detection imaging. The present invention realizes the functions of dual-wavelength laser ranging, laser beam monitoring, visible light detection imaging and short-wave infrared detection imaging, and solves the problem that laser ranging telescopes with a diameter of more than 500 mm cannot achieve multi-wavelength detection, and an optical telescope needs to be separately equipped for imaging detection and beam monitoring.

Description

Technical Field

[0001] The invention belongs to the technical field of space target laser ranging, and in particular relates to a dual-band laser ranging optical structure. Background Art

[0002] Space target laser ranging technology is an observation technology that uses laser pulses to measure the distance from the ground observation station to the space target. It is the technical means with the highest ranging accuracy in the entire detection system and can effectively improve the upper limit of the ranging data accuracy of space targets. By utilizing the high-precision characteristics of the laser ranging telescope, dangerous events of space targets can be precisely monitored to support the final risk assessment and provide support for decision-making on dangerous events. The ranging accuracy is greatly affected by the aperture of the laser ranging telescope, that is, the larger the aperture of the laser ranging telescope, the stronger the ability to receive echo photons. Therefore, as the requirements for the ranging accuracy of space targets increase, the aperture of the laser ranging telescope is also getting larger.

[0003] Due to the limitation of optical element material preparation, currently all large-aperture laser ranging telescopes with an aperture of more than 500mm are single-wavelength laser ranging optical systems, and cannot take into account multiple spectral imaging detection and laser beam monitoring functions. They need to be equipped with separate optical telescopes for imaging detection or laser beam monitoring. Therefore, it is urgent to design and implement dual-wavelength or even multi-wavelength laser ranging for laser ranging telescopes with an aperture of more than 500mm. Summary of the invention

[0004] In view of this, the present invention aims to provide a dual-band laser ranging optical structure for an aperture of 500mm or more, which realizes the dual-wavelength laser ranging function while also having visible light and short-wave infrared imaging detection and laser beam monitoring functions, thereby solving the problem that the existing large-aperture laser ranging telescope can only realize single-wavelength detection and needs to be equipped with a separate optical telescope for imaging detection or laser beam monitoring.

[0005] To achieve the above object, the technical solution created by the present invention is implemented as follows:

[0006] The invention provides a dual-band laser ranging optical structure, comprising: a main optical system for acquiring a target light beam, and a ranging unit;

[0007] The distance measuring unit comprises:

[0008] a first beam splitter, which is used to split the target light beam into visible light and short-wave infrared;

[0009] A second beam splitter is disposed on the propagation optical path of visible light, and the second beam splitter is configured to split the visible light into: a beam of partial 532 nm band light and a beam of mixed light of the remaining 532 nm band and 600 - 900 nm band; wherein, the partial 532 nm band light is used for laser ranging, and the remaining 532 nm band in the mixed light of the remaining 532 nm band and 600 - 900 nm band is used for beam monitoring, and the 600 - 900 nm band is used for laser imaging;

[0010] A third beam splitter is disposed on the propagation optical path of short - wave infrared, and the third beam splitter is configured to split the short - wave infrared into: a beam of partial 1064 nm band light and a beam of mixed light of the remaining 1064 nm band and 1100 - 1700 nm band; wherein, the partial 1064 nm band light is used for laser ranging, and the remaining 1064 nm band in the mixed light of the remaining 1064 nm band and 1100 - 1700 nm band is used for beam monitoring, and the 1100 - 1700 nm band is used for laser imaging.

[0011] Preferably, the main optical system is a Cassegrain system, including a primary mirror and a secondary mirror, wherein the primary mirror is a paraboloid and the secondary mirror is a hyperboloid.

[0012] Preferably, the ranging unit is disposed on the rear optical path of the first image plane of the main optical system.

[0013] Preferably, the ranging unit further includes a collimating lens group disposed on the front optical path of the first beam splitter.

[0014] Preferably, the second beam splitter has a partial reflection and partial transmission effect on the 532 nm band and a total reflection or total transmission effect on the 600 - 900 nm band.

[0015] Preferably, the third beam splitter has a partial reflection and partial transmission effect on the 1064 nm band and a total reflection or total transmission effect on the 1100 - 1700 nm band.

[0016] Preferably, a first lens group for focusing the partial 532 nm band light and coupling it into an optical fiber for ranging is disposed on the propagation optical path of the partial 532 nm band light;

[0017] A second lens group and a third lens group for focusing the mixed light of the remaining 532 nm band and 600 - 900 nm band, monitoring the remaining 532 nm band of the beam, and imaging the target in the first field of view for the 600 - 900 nm band are disposed on the propagation optical path of the mixed light of the remaining 532 nm band and 600 - 900 nm band.

[0018] Preferably, a fourth lens group for focusing the partial 1064-nm band light and coupling it into an optical fiber for distance measurement is provided on the propagation optical path of the partial 1064-nm band light;

[0019] On the propagation optical path of the remaining mixed light of the 1064-nm band and the 1100-1700-nm band, a fifth lens group and a sixth lens group are provided for focusing the remaining mixed light of the 1064-nm band and the 1100-1700-nm band, monitoring the light beam of the remaining 1064-nm band, and imaging the target of the second field of view for the 1100-1700-nm band.

[0020] Preferably, the collimating lens group has a positive optical power, and its focal length is 270 mm - 290 mm;

[0021] The first lens group has a positive optical power, and its focal length is 240 mm - 250 mm;

[0022] The second lens group has a positive optical power, and its focal length is 460 mm - 470 mm;

[0023] The third lens group has a positive optical power, and its focal length is 130 mm - 140 mm;

[0024] The fourth lens group has a positive optical power, and its focal length is 195 - 205 mm;

[0025] The fifth lens group has a positive optical power, and its focal length is 190 mm - 200 mm;

[0026] The sixth lens group has a positive optical power, and its focal length is 110 mm - 130 mm.

[0027] Preferably, the collimating lens group is a cemented lens of a first lens and a second lens, wherein the refractive index and Abbe number of the first lens satisfy:

[0028] ;

[0029] ;

[0030] The refractive index and Abbe number of the second lens satisfy:

[0031] ;

[0032] ;

[0033] All the lenses in the first lens group are made of the same material, and the refractive index and Abbe number both satisfy:

[0034] ;

[0035] ;

[0036] The second lens group includes at least 5 lenses made of different preparation materials, and the refractive index of the lens made of the first preparation material in the second lens group and Abbe number satisfy:

[0037] ;

[0038] ;

[0039] The refractive index of the lens made of the second preparation material in the second lens group and Abbe number respectively satisfy:

[0040] ;

[0041] ;

[0042] The refractive index of the lens made of the third preparation material in the second lens group and Abbe number respectively satisfy:

[0043] ;

[0044] ;

[0045] The refractive index of the lens made of the fourth preparation material in the second lens group and Abbe number respectively satisfy:

[0046] ;

[0047] ;

[0048] The refractive index of the lens made of the fifth preparation material in the second lens group and Abbe number respectively satisfy:

[0049] ;

[0050] ;

[0051] The third lens group includes at least lenses made of 3 different preparation materials, and the refractive index and Abbe number of the lens made of the first preparation material in the third lens group satisfy:

[0052] ;

[0053] ;

[0054] The refractive index and Abbe number of the lens made of the second preparation material in the third lens group satisfy:

[0055] ;

[0056] ;

[0057] The refractive index and Abbe number of the lens made of the third preparation material in the third lens group satisfy:

[0058] ;

[0059] ;

[0060] All lenses in the fourth lens group are made of the same material, and the refractive index and Abbe number of the preparation material both satisfy:

[0061] ;

[0062] ;

[0063] The fifth lens group includes at least lenses made of 3 different preparation materials, and the refractive index and Abbe number of the lens made of the first preparation material in the fifth lens group satisfy:

[0064] ;

[0065] ;

[0066] The refractive index and Abbe number of the lens made of the second preparation material in the fifth lens group satisfy:

[0067] ;

[0068] ;

[0069] The refractive index of the lens made of the third preparation material in the fifth lens group and the Abbe number Satisfy:

[0070] ;

[0071] ;

[0072] Each lens in the sixth lens group is made of the same material, and the refractive index and the Abbe number of the preparation material

[0073] All satisfy:

[0074] .

[0075] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0076] Based on a refractive-reflective hybrid optical system, the present invention uses a combination of lenses, beam splitters and mirrors for multi-spectrum functional applications, realizing the dual-wavelength laser ranging functions of 532 nm and 1064 nm, the monitoring of 532 nm and 1064 nm laser beams, as well as the detection imaging of a 20-minute field of view in visible light and the detection imaging of a 10-minute field of view in short-wave infrared. It solves the problem that a laser ranging telescope with a diameter of more than 500 mm cannot achieve multi-wavelength detection and requires a separate optical telescope for imaging detection and laser beam monitoring, improves the functional integration and structural compactness, and realizes the expansion of the functions of the laser ranging optical system.

[0077] The present invention specially optimizes each lens group, and performs aberration correction through a reasonable combination of lenses, mirrors and dichroic mirrors. Since the entire system has a large field of view and a wide working band, a specific combination of lens materials with refractive index dispersion coefficients is used to correct off-axis aberrations and chromatic aberrations, correcting the aberrations and chromatic aberrations in the visible light and short-wave infrared spectral bands, and improving the imaging quality. In addition, the ranging unit is arranged at the rear end of the first image plane of the Cassegrain system, realizing the segmented design of the main optical system and the ranging optical path, avoiding the mutual interference generated during the assembly and adjustment process, improving the convenience of the optical assembly and adjustment detection of the system, and enabling the separate assembly and adjustment detection of the main optical system and the ranging optical path at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0078] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0079] Figure 1It is a schematic optical path diagram of a dual-band laser ranging optical structure provided according to an embodiment of the present invention;

[0080] Figure 2 It is a schematic optical path diagram of a ranging unit provided according to an embodiment of the present invention.

[0081] The reference numerals therein include:

[0082] Main optical system A, main mirror 1, secondary mirror 2, first reflector 3;

[0083] Ranging unit B, collimating lens group 4, first dichroic mirror 5, second dichroic mirror 6, first lens group 7, second lens group 8, third lens group 9, second reflector 10, third dichroic mirror 11, fourth lens group 12, third reflector 13, fifth lens group 14, sixth lens group 15. Specific embodiments

[0084] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but do not constitute a limitation to the present invention. Similar elements in different embodiments are labeled with related similar element numbers. In the following embodiments, many details are described to make the present invention better understood. However, those skilled in the art can easily recognize that some of the features can be omitted in different situations, or can be replaced by other elements, materials, methods. In some cases, some operations related to the present invention are not shown or described in the specification, which is to avoid the core part of the present invention being overwhelmed by excessive description. For those skilled in the art, it is not necessary to describe these related operations in detail, and they can fully understand the related operations according to the description in the specification and the general technical knowledge in the field.

[0085] It should be noted that, without conflict, the embodiments and features in the embodiments of the present invention can be combined with each other to form various embodiments. At the same time, the steps or actions in the method description can also be adjusted in the order that can be obvious to those skilled in the art. Therefore, the various orders in the specification and drawings are only for clearly describing a certain embodiment, and do not mean that they are the necessary orders, unless it is stated that a certain order must be followed.

[0086] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention. In addition, terms such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise stated, the meaning of "a plurality of" is two or more.

[0087] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "mounted", "connected", and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific circumstances.

[0088] The present invention will be described in detail below with reference to the drawings and in conjunction with embodiments.

[0089] Please refer to Figure 1 and Figure 2In one embodiment of the present invention, a dual-band laser ranging optical structure is provided to solve the problem that currently large-aperture laser ranging telescopes with an aperture of more than 500 mm can only achieve single-wavelength laser ranging. Due to the constraints of optical material preparation technology, systems with an aperture of more than 500 mm only support laser ranging with a single wavelength (such as 532nm or 1064nm), and cannot take into account the dual-band applications of visible light and short-wave infrared. In addition, the existing system needs to be equipped with an additional independent telescope to achieve imaging detection or laser beam monitoring, resulting in a complex structure and low integration. Under the conditions of large field of view and wide band, the correction effect of off-axis aberration and chromatic aberration is limited, affecting the imaging quality. To solve the above problems, the embodiment of the present invention integrates and designs a dual-band ranging optical structure based on the traditional Cassegrain system. Specifically, the dual-band laser ranging optical structure is a large-aperture, multi-spectral, multi-terminal optical structure, which mainly includes a main optical system A and a ranging unit B; wherein the main optical system A is a classic Cassegrain optical structure, that is, it includes a primary mirror 1 and a secondary mirror 2, the primary mirror 1 is a parabola, and the secondary mirror 2 is a hyperbolic surface. The primary mirror 1 collects the light reflected from the target at infinity, and after being reflected by the primary mirror 1, the light is reflected again by the secondary mirror 2 and focused on the first reflector 3 near the focus of the primary mirror 1, and is reflected to the ranging unit B by the first reflector 3.

[0090] Considering the convenience of optical adjustment and detection of the system, the distance measuring unit B is designed after the first image plane of the main optical system A, so that the main optical system A and the distance measuring unit B can be adjusted and detected separately during the optical debugging process, and debugging interference between the two can be avoided. The distance measuring unit B includes a collimating lens group 4 and a first dichroic mirror 5 arranged along the incident propagation direction of the target light beam, as well as a subsequent visible light path and a short-wave infrared light path, wherein the collimating lens group 4 is used to collimate the target light beam collected by the main optical system A, and the target light beam is processed into a collimated light beam after passing through the collimating lens group 4, and then incident on the first dichroic mirror 5, and the first dichroic mirror 5 is used to split the collimated target light beam into visible light and short-wave infrared, and the visible light mainly includes 532nm band light for visible light ranging and 600nm-900nm band light for laser detection imaging; the short-wave infrared mainly includes 1064nm band light for infrared laser ranging and 1100nm-1700nm band light for laser detection imaging. To ensure optical efficiency, the first dichroic mirror 5 is designed to transmit the short-wave infrared spectrum and reflect the visible spectrum. The visible light and short-wave infrared are respectively injected into the subsequent visible light path and short-wave infrared light path.

[0091] In the optical path of the visible light band, a second dichroic mirror 6 is provided along the propagation optical path of the visible light. The second beam splitter 6 is designed to have partial reflection and partial transmission effects on the 532nm band, and total reflection or total transmission effects on the 600nm - 900nm band to achieve spectral splitting. In the embodiment of the present invention, the second beam splitter 6 reflects 60% of the 532nm wavelength light in the visible light spectrum band towards the first lens group 7 for laser ranging; after transmitting the remaining 40% of the 532nm wavelength light and all the light in the 600nm - 900nm band, it continues to be incident on the second lens group 8 and the third lens group 9 and other target imaging and beam monitoring optical paths.

[0092] After passing through the second beam splitter 6, the light is divided into two beams. One beam is 60% of the 532nm wavelength light, which is incident on the first lens group 7. The first lens group 7 focuses the laser echo beam and focuses it into a beam with a numerical aperture NA = 0.22, and couples it into a multimode optical fiber for subsequent visible light laser ranging. The other beam, a mixed light composed of the remaining 532nm band light and the 600nm - 900nm band light, is incident on the second lens group 8 and the third lens group 9. The second lens group 8 and the third lens group 9 are used to perform secondary beam reduction, collimation, and focusing on the mixed light composed of the 532nm band light and the 600nm - 900nm band light. The target of the secondary beam reduction and collimation is to place a field stop and a filter. The second lens group 8 and the third lens group 9 focus the 532nm band light and the 600nm - 900nm band light into a beam with a focal length f = 3500mm to achieve visible light imaging and optical monitoring of a target field of view of 20 minutes.

[0093] In the optical path of the short-wave infrared light band, a second mirror 10, a third dichroic mirror 11, and a third mirror 13 are provided along the propagation optical path of the short-wave infrared. Among them, both the second mirror 10 and the third mirror 13 are used to change the propagation direction of the beam, rationally design the optical path, and reduce the overall size of the system. After the short-wave infrared is reflected by the second mirror 10, it is incident on the third dichroic mirror 11. The third dichroic mirror 11 is designed to have partial reflection and partial transmission effects on the 1064nm band, and total reflection or total transmission effects on the 1100nm - 1700nm band to achieve spectral splitting. In the embodiment of the present invention, the third dichroic mirror 11 reflects 60% of the 1064nm wavelength light in the short-wave infrared spectrum band towards the fourth lens group 12 for laser ranging in the infrared band; after transmitting the remaining 40% of the 1064nm wavelength light and all the light in the 1100nm - 1700nm band, it continues to be incident on the third mirror 13, and the third mirror 13 reflects this part of the light towards the fifth lens group 14 and the sixth lens group 15 for target imaging and beam monitoring in the infrared band.

[0094] After passing through the third dichroic mirror 11, the split light beam is divided into two beams. One beam is 60% of the 1064 nm wavelength light, which is directed towards the fourth lens group 12. The fourth lens group 12 focuses the laser echo beam and focuses it into a beam with a numerical aperture NA = 0.22, and couples it into a multimode optical fiber for subsequent laser ranging in the infrared band. The other beam, which is a mixed light composed of the remaining 1064 nm band light and the 1100 nm - 1700 nm band light, is directed towards the third mirror 13. The third mirror 13 reflects this part of the light towards the fifth lens group 14 and the sixth lens group 15. The fifth lens group 14 and the sixth lens group 15 are used to focus the mixed light composed of the remaining 1064 nm band light and the 1100 nm - 1700 nm band light into a beam with a focal length f = 4200 mm, realizing infrared band imaging and optical monitoring of a target field of view of 10 minutes.

[0095] The dual - band laser ranging optical structure obtained through the above design can achieve coverage of telescopes with an aperture of 500 mm and above in the visible spectral band and the short - wave infrared spectral band. It can achieve dual - band laser ranging in the infrared and visible bands, and the field of view for visible light imaging and monitoring can reach 20 minutes, and the field of view for short - wave infrared imaging and monitoring can reach 10 minutes, meeting the current requirements of a visible light optical field of view of 8 minutes and a short - wave infrared optical field of view of 5 minutes. Moreover, the imaging effect is good. In the case of dual - band ranging, it can realize visible light and short - wave infrared imaging detection and laser beam monitoring functions without the aid of additional equipment. By directly installing it on the laser ranging telescope machine and rotating it together with the telescope, dual - band ranging and imaging monitoring can be achieved, with the characteristics of a compact structure, simple integration, and excellent image quality.

[0096] The dual - band laser ranging optical structure of the embodiment of the present invention is composed of lenses, mirrors, dichroic mirrors, etc., and is a catadioptric hybrid optical system. Since the entire system has a relatively large field of view and a relatively wide working band, it is necessary to reasonably combine the lenses, mirrors, and dichroic mirrors for aberration correction, and use a specific combination of lens materials with refractive index dispersion coefficients to correct off - axis aberration and chromatic aberration. Specifically, through a large amount of creative work, the following specific parameter data are obtained:

[0097] First, in the embodiments of the present invention, the first dichroic mirror 5, the second dichroic mirror 6, and the third dichroic mirror 11 are all double-sided high-precision plane-parallel plates, and are at an angle of 45° with the system optical axis. The collimating lens group 4, the first lens group 7, the second lens group 8, the third lens group 9, the fourth lens group 12, the fifth lens group 14, and the sixth lens group 15 are all spherical lenses with optical power, and the connecting lines of the centers of all the lenses coincide with the system optical axis. Among them, the collimating lens group 4 has positive optical power and is a cemented lens composed of a first lens and a second lens. The two surfaces and the cemented interface thereof are all spherical surfaces, and the connecting line of the centers of the front and back double surfaces coincides with the system optical axis, and its focal length is 270 mm - 290 mm. To solve the chromatic aberration problem, the collimating lens group 4 uses two different grades of optical materials. It should be noted that here it means that the two lenses respectively use two different materials, rather than each lens being prepared with two different mixed materials. The refractive index and Abbe number of the first lens satisfy:

[0098] ;

[0099] ;

[0100] The refractive index and Abbe number of the second lens satisfy:

[0101] ;

[0102] .

[0103] The first lens group 7 has positive optical power and is composed of 3 spherical lenses. The connecting lines of all the centers coincide with the system optical axis, and its focal length is 240 mm - 250 mm. Each lens in the first lens group 7 is made of the same material and only includes one grade of optical material. The refractive index and Abbe number of its preparation material both satisfy:

[0104] ;

[0105] .

[0106] The second lens group 8 has positive optical power and is composed of 5 spherical lenses. The connecting lines of all the centers coincide with the system optical axis, and its focal length is 460 mm - 470 mm. Each lens in the second lens group 8 is made of different materials and includes lenses prepared from 5 different grades of optical materials. The refractive index and Abbe number of these 5 different grades of optical materials respectively satisfy:

[0107] The refractive index of the lens made of the first preparation material in the second lens group 8 and the Abbe number Satisfy:

[0108] ;

[0109] .

[0110] The refractive index of the lens made of the second preparation material in the second lens group 8 and the Abbe number Respectively satisfy:

[0111] ;

[0112] .

[0113] The refractive index of the lens made of the third preparation material in the second lens group 8 and the Abbe number Respectively satisfy:

[0114] ;

[0115] .

[0116] The refractive index of the lens made of the fourth preparation material in the second lens group 8 and the Abbe number Respectively satisfy:

[0117] ;

[0118] .

[0119] The refractive index of the lens made of the fifth preparation material in the second lens group 8 and the Abbe number Respectively satisfy:

[0120] ;

[0121] .

[0122] The third lens group 9 has a positive optical power and is composed of 3 spherical lenses. The connecting lines of all the centers of the spheres coincide with the optical axis of the system, and its focal length is 130 mm - 140 mm. Each lens in the third lens group 9 is made of a different material, including lenses made of 3 different grades of optical materials. The refractive indices and the Abbe numbers Respectively satisfy:

[0123] The refractive index of the lens made of the first preparation material in the third lens group 9 and Abbe number Satisfy:

[0124] ;

[0125] .

[0126] The refractive index of the lens made of the second preparation material in the third lens group 9 and Abbe number Satisfy:

[0127] ;

[0128] .

[0129] The refractive index of the lens made of the third preparation material in the third lens group 9 and Abbe number Satisfy:

[0130] ;

[0131] .

[0132] The fourth lens group 12 has a positive optical power and is composed of 3 spherical lenses. The connecting line of all the centers of the spheres coincides with the optical axis of the system, and its focal length is 195 - 205 mm. Each lens in the fourth lens group 12 is made of the same material and only includes a lens made of 1 type of optical material with different grades. The refractive index of this different-grade optical material and Abbe number Satisfy:

[0133] ;

[0134] .

[0135] The fifth lens group 14 has a positive optical power and is composed of 3 spherical lenses. The connecting line of all the centers of the spheres coincides with the optical axis of the system, and its focal length is 190 mm - 200 mm. Each lens in the fifth lens group 14 is made of different materials and includes lenses made of 3 types of optical materials with different grades. The refractive indices of these 3 types of optical materials with different grades and Abbe number Respectively satisfy:

[0136] The refractive index of the lens made of the first preparation material in the fifth lens group 14 and Abbe number Satisfy:

[0137] ;

[0138] .

[0139] The refractive index of the second lens made of the preparation material in the fifth lens group 14 and the Abbe number Satisfy:

[0140] ;

[0141] .

[0142] The refractive index of the third lens made of the preparation material in the fifth lens group 14 and the Abbe number Satisfy:

[0143] ;

[0144] .

[0145] The sixth lens group 15 has a positive optical power and is composed of 2 spherical lenses. The connection line of all the centers of the spheres coincides with the optical axis of the system, and its focal length is 110 mm - 130 mm. Each lens in the sixth lens group 15 is made of the same material and only includes lenses made of 1 kind of optical material with different grades. The refractive index of this optical material with different grades and the Abbe number Satisfy:

[0146] ;

[0147] .

[0148] The dual-band laser ranging optical structure with a diameter of more than 500 mm designed according to the above parameters and optical structure realizes the dual-wavelength laser ranging function, and also has functions such as visible light and short-wave infrared imaging detection and laser beam monitoring, etc., solving the disadvantages that the existing large-aperture laser ranging telescopes can only realize single-wavelength detection, and an additional optical telescope needs to be separately equipped for imaging detection or laser beam monitoring.

[0149] In summary, the above is only the preferred embodiment of this specification and is not used to limit the protection scope of this specification. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this specification shall be included within the protection scope of this specification.

[0150] The systems, devices, modules or units described in one or more of the above embodiments may be specifically implemented by computer chips or entities, or by products with certain functions. A typical implementation device is a computer. Specifically, the computer may be, for example, a personal computer, a laptop computer, a cellular phone, a camera phone, a smart phone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or any combination of these devices.

[0151] It should also be noted that the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, commodity or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, commodity or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, commodity or device comprising the element.

[0152] Each embodiment in this specification is described in a progressive manner. The same or similar parts among the embodiments can be referred to each other, and the differences between each embodiment and other embodiments are emphasized. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the description of the method embodiment.

[0153] The specific embodiments of this specification are described above. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims may be performed in a different order than in the embodiments and still achieve the desired results. Additionally, the processes depicted in the figures do not necessarily require the particular order or sequential order shown to achieve the desired results. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

Claims

1. A dual-band laser ranging optical structure, characterized in that, Comprising: A main optical system for obtaining a target beam, and a ranging unit; The ranging unit includes: A first beam splitter for splitting the target beam into visible light and short-wave infrared; A second beam splitter is disposed on the propagation optical path of the visible light. The second beam splitter is used to split the visible light into: a beam of partial 532nm band light, and a beam of mixed light of the remaining 532nm band and 600nm - 900nm band; wherein, the partial 532nm band light is used for laser ranging, and the mixed light of the remaining 532nm band and 600nm - 900nm band is used for beam monitoring and laser imaging; A third beam splitter is disposed on the propagation optical path of the short-wave infrared. The third beam splitter is used to split the short-wave infrared into: a beam of partial 1064nm band light, and a beam of mixed light of the remaining 1064nm band and 1100nm - 1700nm band; wherein, the partial 1064nm band light is used for laser ranging, and the mixed light of the remaining 1064nm band and 1100nm - 1700nm band is used for beam monitoring and laser imaging; The ranging unit further includes a collimating lens group disposed on the front optical path of the first beam splitter; On the propagation optical path of the partial 532nm band light, there is a first lens group for focusing the partial 532nm band light and coupling it into an optical fiber for ranging; On the propagation optical path of the mixed light of the remaining 532nm band and 600nm - 900nm band, there are a second lens group and a third lens group for focusing the mixed light of the remaining 532nm band and 600nm - 900nm band, and for beam monitoring of the remaining 532nm band and first field of view target imaging for the 600nm - 900nm band; On the propagation optical path of the partial 1064nm band light, there is a fourth lens group for focusing the partial 1064nm band light and coupling it into an optical fiber for ranging; On the propagation optical path of the mixed light of the remaining 1064nm band and 1100nm - 1700nm band, there are a fifth lens group and a sixth lens group for focusing the mixed light of the remaining 1064nm band and 1100nm - 1700nm band, and for beam monitoring of the remaining 1064nm band and second field of view target imaging for the 1100nm - 1700nm band.

2. The dual-band laser ranging optical structure according to claim 1, characterized in that The main optical system is a Cassegrain system, including a primary mirror and a secondary mirror, where the primary mirror is a paraboloid and the secondary mirror is a hyperboloid.

3. The dual-band laser ranging optical structure according to claim 2, wherein The ranging unit is disposed on the rear optical path of the first image plane of the main optical system.

4. The dual-band laser ranging optical structure according to any one of claims 1-3, characterized in that, The second beam splitter has a partial reflection and partial transmission effect on the 532nm band, and a total reflection or total transmission effect on the 600nm - 900nm band.

5. The dual-band laser ranging optical structure according to any one of claims 1-3, characterized in that, The third beam splitter has a partial reflection and partial transmission effect on the 1064nm band, and a total reflection or total transmission effect on the 1100nm - 1700nm band.

6. The dual-band laser ranging optical structure according to claim 5, wherein, The collimating lens group has a positive optical power, and its focal length is 270mm - 290mm; The first lens group has a positive optical power, and its focal length is 240mm - 250mm; The second lens group has a positive optical power, and its focal length is 460 mm - 470 mm; The third lens group has a positive optical power, and its focal length is 130 mm - 140 mm; The fourth lens group has a positive optical power, and its focal length is 195 - 205 mm; The fifth lens group has a positive optical power, and its focal length is 190 mm - 200 mm; The sixth lens group has a positive optical power, and its focal length is 110 mm - 130 mm.

7. The dual-band laser ranging optical structure according to claim 6, characterized in that, The collimating lens group is a cemented lens of a first lens and a second lens, wherein the refractive index and Abbe number satisfy: ； ； Refractive index of the second lens and Abbe number satisfy: ； ； Each lens in the first lens group is made of the same material, and the refractive index and Abbe number of the preparation material both satisfy: ； ； At least five lenses made of different preparation materials are included in the second lens group, and the refractive index and Abbe number of the lens made of the first preparation material in the second lens group satisfy: ； ； The refractive index of the second lens made of the second preparation material in the second lens group and the Abbe number respectively satisfy: ； ； The refractive index of the lens made of the third preparation material in the second lens group and the Abbe number respectively satisfy: ； ； The refractive index of the lens made of the fourth preparation material in the second lens group and the Abbe number respectively satisfy: ； ； The refractive index of the lens made of the fifth preparation material in the second lens group and the Abbe number respectively satisfy: ； ； The third lens group includes at least lenses made of three different preparation materials, and the refractive index and Abbe number of the lens made of the first preparation material in the third lens group satisfy: ； ； The refractive index of the second preparation material lens in the third lens group and Abbe number satisfy: ； ； The refractive index of the lens made of the third preparation material in the third lens group and the Abbe number satisfy: ； ； The materials of the lenses in the fourth lens group are the same, and the refractive index and Abbe number both satisfy: ； ； The fifth lens group includes at least three lenses made of different preparation materials, and the refractive index and Abbe number of the lens made of the first preparation material in the fifth lens group satisfy: ； ； The refractive index of the second preparation material lens in the fifth lens group and the Abbe number satisfy: ； ； The refractive index of the lens made of the third preparation material in the fifth lens group and the Abbe number satisfy: ； ； Each lens in the sixth lens group is made of the same material, and the refractive index and Abbe number of the preparation material both satisfy: ； 。

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