Laser range finder

Abstract

The invention discloses a laser range finder, which comprises a visual system, a laser emission system and a laser receiving system, and is characterized in that the visual system is provided for a user to observe a target; the laser emission system comprises a laser, a polarization state converter and a first lens group, the polarization state converter can convert various preset polarization states, first ranging laser emitted by the laser forms second ranging laser in a preset polarization state after passing through the polarization state converter, and the second ranging laser is emitted to a target through the first lens group; and the laser receiving system is used for detecting echo laser reflected by the target to the second ranging laser so as to determine the distance of the target by using the echo laser. In this way, the distance measuring range can be enlarged.

Description

Technical Field

[0001] The present application relates to the technical field of optical distance measurement, and in particular to a laser distance meter. Background Art

[0002] Laser rangefinder is an instrument that uses laser to measure the distance to a target. At present, laser rangefinder is widely used in various outdoor scenes.

[0003] Since the light output power of the laser rangefinder is limited, and the emitted laser will gradually lose power due to various factors such as distance and target reflection, when the target is relatively far away, the laser rangefinder may not be able to detect the echo laser of sufficient intensity, and thus cannot achieve distance measurement. Summary of the invention

[0004] The main technical problem solved by the present application is to provide a laser rangefinder capable of increasing the ranging range.

[0005] In order to solve the above technical problems, a technical solution adopted in the present application is: providing a laser rangefinder, which includes a visual system, a laser emitting system and a laser receiving system, wherein the visual system is used to provide a user with an opportunity to observe a target; the laser emitting system includes a laser, a polarization state converter and a first lens group, the polarization state converter can convert a plurality of preset polarization states, a first ranging laser emitted by the laser forms a second ranging laser with a preset polarization state after passing through the polarization state converter, and the second ranging laser is emitted to the target through the first lens group; the laser receiving system is used to detect the echo laser reflected by the target from the second ranging laser, so as to determine the distance of the target using the echo laser.

[0006] In some embodiments, the polarization state converter includes at least one polarization element sequentially arranged along the light transmission direction, and the at least one polarization element includes at least one of a polarization light filter and a polarization state adjuster.

[0007] Wherein, the polarized light filter comprises a coated mirror and a grating, and the polarization state regulator is a wave plate.

[0008] In some embodiments, the polarization element includes a substrate and a plurality of polarization zones disposed on the substrate, and different polarization zones correspond to different polarization states.

[0009] Wherein, the geometric center of each of the polarization zones is coaxial with the center of the first ranging laser.

[0010] Wherein, the plurality of polarization zones are arranged around the center of the substrate.

[0011] Wherein, the position on the substrate corresponding to the polarization zone is hollowed out.

[0012] Wherein, the substrate is a disc substrate.

[0013] The laser rangefinder further comprises an electric control unit, and the electric control unit is used to drive each of the polarization elements to rotate so as to select a polarization zone of the polarization element to be located in the optical path where the first ranging laser is located.

[0014] Wherein, the at least one polarization element comprises a coated mirror, a grating and a wave plate which are sequentially arranged along the light transmission direction; wherein the multiple polarization zones corresponding to the coated mirror are multiple sub-coated mirrors; the multiple polarization zones corresponding to the grating are multiple sub-gratings; and the multiple polarization zones corresponding to the wave plate are multiple sub-wave plates.

[0015] In some embodiments, the first lens group includes a first lens, an optical path changing element, and a second lens, wherein the second ranging laser is emitted to the optical path changing element through the first lens, is incident to the second lens after the optical path is changed by the optical path changing element, and is emitted to the target through the second lens.

[0016] Among them, the second lens is the objective lens in the visual system, and the optical path changing element includes a first optical path changing element and a second optical path changing element, wherein the second optical path changing element is the second prism in the visual system, and the first optical path changing element is a first reflector or a second prism. The second ranging laser emitted by the first lens is incident on the first prism in the visual system through the first optical path changing element, and is emitted to the target after passing through the first prism and the objective lens in sequence.

[0017] In some embodiments, the laser receiving system includes a second lens group and a detector, wherein the detector is provided with a photosensitive surface, and the echo laser is incident on the photosensitive surface of the detector through the second lens group.

[0018] Wherein, the laser receiving system further includes a second reflector, and the echo laser emitted by the second lens group is incident on the photosensitive surface of the detector through the second reflector.

[0019] In some embodiments, the visual system includes an objective lens, an eyepiece, a first prism and a display screen, wherein the first prism is disposed between the objective lens and the eyepiece, and the display screen is disposed at the object focus of the eyepiece.

[0020] In the above scheme, the laser emission system in the laser rangefinder is equipped with a polarization state converter, which can convert multiple preset polarization states. Therefore, when measuring the distance of a target, a preset polarization state in which the target has a higher reflectivity can be selected from multiple preset polarization states, and then the first ranging laser emitted by the laser is converted into a second ranging laser of the selected preset polarization state, and then emitted to the target. Since the target has a higher reflectivity to the preset polarization state, the intensity of the echo laser is relatively large. Even if the distance of the target is far, the laser rangefinder can detect the echo laser, thereby realizing ranging. Therefore, when the output light power of the laser rangefinder remains unchanged, the ranging range is increased, and when the ranging range remains unchanged, the output light power of the laser rangefinder can also be reduced, saving the energy consumption of the laser rangefinder. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of an embodiment of the laser rangefinder of the present application;

[0022] Figure 2 is a schematic structural diagram of a polarization element in another embodiment of the laser rangefinder of the present application;

[0023] Figure 3 is a schematic structural diagram of a polarization state converter in yet another embodiment of the laser rangefinder of the present application;

[0024] Figure 4 It is a schematic diagram of the operation of a polarization state converter in yet another embodiment of the laser rangefinder of the present application. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and effect of the present application clearer and more specific, the present application is further described in detail with reference to the accompanying drawings and examples. It should be noted that the multiple mentioned herein should be understood as at least two.

[0026] See also Figure 1 , Figure 1 It is a schematic diagram of the structure of an embodiment of the laser rangefinder of the present application. In this embodiment, the laser rangefinder 10 includes a visual system 11, a laser emitting system 12 and a laser receiving system 13. Among them, the visual system 11 and the laser ranging system 12 are relatively fixedly arranged. The visual system 11 is used to provide the user with a target for observation. The laser emitting system 12 and the laser receiving system 13 constitute a laser ranging system, wherein the laser emitting system 12 is used to emit a ranging laser to the target observed by the user, and the laser receiving system 13 is used to detect the echo laser reflected by the target to the ranging laser, so as to determine the distance of the target by using the echo laser, and then realize the ranging of the target observed by the user.

[0027] Specifically, the visual system 11 may include an eyepiece 111, a first prism 112, and an objective lens 113. The first prism 112 is disposed between the objective lens 113 and the eyepiece 111, and the line connecting the centers of the eyepiece 111, the first prism 112, and the objective lens 113 forms the optical axis of the visual system 11. In the present embodiment, the eyepiece 111, the first prism 112, and the objective lens 113 form a telescope. Among them, the objective lens 113 is used to collect and focus light from the target, which may be a large-aperture spherical or aspherical lens or a reflector. The eyepiece 111 is used to further amplify the light focused by the objective lens 113 to form an image for the observer to observe, which may be a small-aperture lens or a reflector. The first prism 112 is used to change the optical path, and may specifically be an image-transferring prism, which is used to realize the conversion of an inverted image into an upright image, etc., so that the observer can observe comfortably through the eyepiece 111. It is understandable that the visual system 11 may be provided with or without the first prism 112 according to actual needs, which is not limited here.

[0028] In some embodiments, the visual system 11 may further include a display screen 114, which is disposed at the object focus of the eyepiece 111 in the visual system 11 to display electronic information. Thus, the observer can view the information displayed on the display screen 114 while observing the target.

[0029] It is understandable that in other embodiments, the visual system may also be configured as other structures as long as the observer can observe the target, so the specific structure of the visual system is limited here.

[0030] The laser emitting system 12 includes a laser 121, a polarization state converter 122, and a first lens group 123. The laser 121 may be, but is not limited to, used to emit a blue laser, and the central axis of the laser may be parallel to the optical axis of the visual system 11. The first lens group 123 is specifically used to form a collimated laser from the second ranging laser, or to form a collimated laser after changing the optical path of the second ranging laser.

[0031] The polarization state converter 122 can convert a plurality of preset polarization states. Thus, when measuring the distance of a target, a preset polarization state can be selected from the plurality of preset polarization states as the target polarization state, and the polarization state converter 122 is set so that the polarization state converter 122 is currently used to convert to the target polarization state. The first ranging laser emitted by the laser 121 passes through the polarization state converter 122 to form a second ranging laser of the target polarization state. The second ranging laser is emitted to the target through the first lens group 123 to detect the target. In some embodiments, the target polarization state required by the target can be determined based on the photoelectric signal collected by the transceiver system for the current target. The transceiver system can be a system in the laser rangefinder 10, such as the aforementioned laser emitting system 11 and laser receiving system 12, or other systems outside the laser rangefinder 10. It can be understood that, in an ideal situation, the polarization state converter 122 emits a laser of a single polarization state according to the design value. However, in actual situations, the laser emitted by the polarization state converter 122 may also contain a small amount of lasers of other polarization states. Therefore, in some specific embodiments, the second ranging laser of the target polarization state formed by the polarization state converter 122 can be understood as the laser emitted by the polarization state converter 122 mainly being the laser of the target polarization state.

[0032] Specifically, the polarization state converter 122 includes at least one polarization element 1221 arranged in sequence along the light transmission direction. Each polarization element 1221 is used to perform polarization processing on the incident laser to achieve the switching of at least one polarization state. For example, a polarization element is used to achieve the switching of multiple polarization states, that is, the user can select a polarization state from the multiple polarization states supported by the polarization element according to actual conditions, and configure the polarization element 1221 to perform polarization processing corresponding to the selected polarization state, thereby emitting the laser of the selected polarization state (which can be understood as mainly the laser of the selected polarization state).

[0033] In some embodiments, in order to achieve the switching of multiple polarization states, the polarization element 1221 may include multiple polarization zones corresponding to different polarization states. Figure 2The polarization element 1221 includes a substrate 12211 and a plurality of polarization zones 12212 disposed on the substrate 12211, and different polarization zones 12212 correspond to different polarization states. That is, when the polarization element emits laser light through different polarization zones 12212, the obtained laser light is in different polarization states. Among them, the geometric center of each polarization zone 12212 can be coaxial with the center of the first ranging laser. In order to increase the light transmittance, the position corresponding to the polarization zone 12212 on the substrate 12211 can be hollowed out. Of course, if the maximum light transmittance is not considered, it may not be hollowed out. For example, the position corresponding to the polarization zone 12212 on the substrate 12211 is provided with a material with a certain degree of transparency. In addition, in order to facilitate switching, the substrate 12211 can be a disk substrate, and the plurality of polarization zones 12212 are arranged around the center of the substrate 12211. Of course, the substrate 12211 can also be provided with other shapes, such as a hexagon, a quadrilateral, etc. The plurality of polarization zones 12212 may not be disposed around the center of the substrate 12211 . For example, the plurality of polarization zones 12212 may be arranged in a straight line on the substrate 12211 .

[0034] In one embodiment, the laser rangefinder 10 further includes an electric control unit (not shown), which is connected to each polarization element 1221 and is used to drive the polarization element 1221 to rotate, so as to select a polarization zone 12212 of the polarization element 1221 to be located in the optical path where the first ranging laser is located, so that the first ranging laser emitted by the laser 121 passes through the polarization zone currently selected for each polarization element, and forms a second ranging laser with a preset polarization state. Specifically, the electric control unit may include a motor, which drives each polarization element 121 to rotate in response to a control signal of the controller of the laser rangefinder 10.

[0035] The aforementioned multiple preset polarization states of the polarization state converter 122 are specifically determined by the polarization states supported by each of the at least one polarization element 1221. It can be understood that in order to achieve the switching of multiple preset polarization states, the at least one polarization element 1221 should have a polarization element that supports multiple polarization states. For example, when the polarization state converter 122 includes only one polarization element 1221, the polarization element 1221 should support multiple polarization states, and the multiple polarization states supported are the preset polarization states supported by the polarization state converter 122. When the polarization state converter 122 includes multiple polarization elements 1221, there should be more than one polarization element 1221 that supports multiple polarization states, and each preset polarization state corresponds to a combination of any polarization states supported by each polarization element 1221, and the number of preset polarization states can be the product of the number of polarization states supported by all or part of the polarization elements 1221.

[0036] In this embodiment, the at least one polarizing element 1221 includes at least one of a polarizing light filter and a polarization state regulator. The polarizing light filter is used to achieve polarization state screening, and may specifically include a grating. Of course, the polarizing light filter may specifically adjust the polarization state before screening. Correspondingly, the polarizing light filter includes a polarizing element 1221 for implementing polarization state modulation and a polarizing element 1221 for implementing polarization state screening, for example, including a coated mirror and a grating in sequence. The polarization state regulator may specifically be at least one polarizing element 1221 such as a wave plate or a coated mirror that can achieve polarization state modulation.

[0037] Combined with reference Figure 3 and 4 In a specific embodiment, the at least one polarizing element 1221 may include a polarization filter and a polarization state adjuster, and the polarization filter 1221 includes a coating 1221a and a grating 1221b, and the polarization state adjuster is a wave plate 1221c. The coating mirror 1221a, the grating 1221b, and the wave plate 1221c are arranged in sequence along the light transmission direction.

[0038] The coated mirror 1221a includes a substrate 12211a and N sub-coated mirrors 12212a, and each sub-coated mirror 12212a serves as a polarization zone, respectively used to realize modulation of different polarization states. Figure 3 In the example, four polarization zones are used, namely, four sub-coated mirrors 12212a, A, B, C and D. Each sub-coated mirror 12212a can be a structure coated on a flat glass. Of course, in other embodiments, it can also be a coating of other materials. The geometric center of the sub-coated mirror 12212a is coaxial with the center of the first ranging laser emitted by the laser 121, and the base at the location is hollowed out.

[0039] Since modulation cannot be 100% and the output light power needs to be controlled, the grating 1221b can be used for screening to increase the proportion of the required polarization state laser in the total power. The grating 1221b includes a base 12211b and N sub-gratings 12212b, each sub-grating 12212b as a polarization zone, respectively used to achieve screening of different polarization states. Figure 3 In the example, four polarization zones are used, namely four sub-gratings 12212b of E, F, G and H. The geometric center of the sub-grating 12212b is coaxial with the center of the first ranging laser emitted by the laser 121, and the base is hollowed out at the location.

[0040] The wave plate 1221ca includes a substrate 12211c and N sub-wave plates 12212c. Each sub-wave plate 12212c serves as a polarization zone and is used to realize modulation of different polarization states. Figure 3In the figure, four polarization zones are taken as an example, namely four sub-wave plates 12212c, J, K, L and Z. The geometric center of the sub-wave plate 12212c is coaxial with the center of the first distance measuring laser emitted by the laser 121, and the base is hollowed out at the location.

[0041] like Figure 4 As shown, the centers of the coated mirror 1221a, the grating 1221b, and the wave plate 1221c are electrically controlled to rotate, so that the electronic control unit of the laser rangefinder 10 can respectively control the coated mirror 1221a, the grating 1221b, and the wave plate 1221c to rotate around the electrically controlled rotation axis to select a sub-coated mirror 12212a, a sub-grating 12212b, and a sub-wave plate 12212c passing through the optical path where the first ranging laser is located. The first ranging laser emitted by the laser 121 is sequentially polarized by the sub-coated mirror 12212a, the sub-grating 12212b, and the sub-wave plate 12212c selected above to form a second ranging laser with a specific polarization state. Among them, the combination of different sub-coated mirrors 12212a, sub-gratings 12212b, and sub-wave plates 12212c can form different preset polarization states. It can be understood that if the multiple preset polarization states include polarization states formed by all combinations of any sub-coated mirror 12212a, any sub-grating 12212b, and any sub-wave plate 12212c, that is, the first ranging laser is modulated by any sub-coated mirror 12212a to obtain a first polarization state laser (the emitted laser is mainly a first polarization state laser), and is screened by any sub-grating 12212b to obtain a second polarization state laser (for example, different sub-gratings perform polarization processing on the first polarization state laser to form a second polarization state laser with a different polarization state), and then modulated by any sub-wave plate 12212c to obtain a preset polarization state laser, then the number M of preset polarization states is equal to N*N*N. If each sub-grating 12212b is understood to be used to filter the first polarization state laser adjusted by its corresponding sub-coated mirror 12212a, that is, N sub-coated mirrors 12212a and N sub-gratings 12212b form N pairs of coated mirrors-sub-gratings, the first ranging laser is modulated and screened by any pair of sub-coated mirrors-sub-gratings to obtain a first polarization state laser (modulated by the sub-coated mirror to obtain an output laser that is mainly a first polarization state laser, and then filtered by the corresponding sub-grating except for the first polarization state, so that the laser emitted by the sub-grating contains a higher proportion of the first polarization state laser or only contains the first polarization state laser), and then modulated by any sub-wave plate 12212c to obtain a preset polarization state laser, then the number of preset polarization states M is equal to N*N.

[0042] Therefore, a polarization state converter can be set to realize the conversion of M kinds of preset polarization state lasers. If the target with the highest reflectivity corresponding to each preset polarization state is known, when observing different targets, the laser emitted by the laser can be converted into a laser with the preset polarization state with the highest reflectivity of the target through the polarization state converter, so that the intensity of the echo laser reflected by the target is improved. Therefore, compared with the traditional rangefinder, under the same output light power, the distance measurement of M kinds of targets at a longer distance can be obtained; or under the same ranging distance conditions, a lower power output laser can be used.

[0043] In this embodiment, the first lens group 123 includes a first lens 1231, an optical path changing element 1232, and a second lens 1233. The first lens 1231 and the second lens 1233 form a laser collimating lens group. The second ranging laser emitted by the polarization state converter 122 is emitted to the optical path changing element 1232 via the first lens 1231, and is incident on the second lens 1233 after the optical path is changed by the optical path changing element 1232, and is emitted to the target via the second lens 1233. The optical path changing element 1232 can be any element that can change the optical path. Specifically, the optical path changing element 1232 can include at least one of a reflector and a prism.

[0044] In order to save the cost and internal space of the laser rangefinder, the objective lens 113 of the visual system can be reused as the second lens 1233, so the optical path changing element 1232 is used to make the laser emitted by the first lens 1231 incident on the objective lens 113. To achieve the above optical path change, the optical path changing element 1232 may specifically include a first optical path changing element 12321 and a second optical path changing element 12322, wherein the second optical path changing element 12322 is the second prism 112 in the visual system 11, and the first optical path changing element 12321 is a first reflector or a second prism, such as Figure 1 As shown, the first optical path changing element 12321 is a second prism 12321. The second ranging laser emitted by the first lens 1231 is reflected by the first optical path changing element 12321 and changes the propagation direction (folded optical path) before being incident on the first prism 112, reflected by the first prism 112 to the objective lens 113, and emitted to the target through the objective lens 113. It can be understood that in other embodiments, the components of the visual system may not be reused, that is, the optical path changing element 1232 and the second lens 1233 are both separately provided optical path elements, and the optical path changing element 1232 may be selected whether to be provided or how to be provided according to the specific positions of the first lens 1231 and the second lens 1233, which is not limited here.

[0045] The laser receiving system 13 includes a second lens group 131 and a detector 132. The detector 132 is provided with a photosensitive surface 132a, and the photosensitive surface 132a is used to receive the echo laser. Specifically, the second lens group 131 may include at least two collimating lenses. After the target reflects the collimated laser emitted by the laser emitting system 12 to obtain the echo laser, the echo laser passes through the second lens group 131 and is incident on the photosensitive surface 132a of the detector 132, and then the distance of the target is determined based on the echo laser detected by the photosensitive surface 132a.

[0046] In some embodiments, considering that the detector 132 is not arranged on the output light path of the second lens group 131, the laser receiving system 13 also includes a second reflector 133. The echo laser emitted by the second lens group 131 is incident on the photosensitive surface 132a of the detector 132 through the second reflector 133, and then the distance of the target is determined based on the echo laser detected by the photosensitive surface 132a.

[0047] In some specific application scenarios, the aforementioned laser rangefinder 10 may be, but is not limited to, a handheld rangefinder.

[0048] The above description is only an implementation method of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A laser rangefinder, characterized in that: The laser rangefinder comprises: Visual system, used to provide users with objects to observe; A laser emitting system, the laser emitting system comprising a laser, a polarization state converter and a first lens group, the polarization state converter being capable of converting a plurality of preset polarization states, a first ranging laser emitted by the laser passing through the polarization state converter forming a second ranging laser of the preset polarization state, the second ranging laser being emitted to the target through the first lens group; The laser receiving system is used to detect the echo laser reflected by the target from the second ranging laser, so as to determine the distance of the target using the echo laser.

2. The laser rangefinder according to claim 1, characterized in that: The polarization state converter includes at least one polarization element sequentially arranged along a light transmission direction, and the at least one polarization element includes at least one of a polarization light filter and a polarization state adjuster.

3. The laser rangefinder according to claim 2, characterized in that: The polarized light filter includes a coated mirror and a grating, and the polarization state regulator is a wave plate.

4. The laser rangefinder according to claim 2 or 3, characterized in that: The polarization element comprises a substrate and a plurality of polarization zones arranged on the substrate, and different polarization zones correspond to different polarization states.

5. The laser rangefinder according to claim 4, characterized in that: The geometric center of each of the polarization zones is coaxial with the center of the first ranging laser; and / or, the plurality of polarization zones are arranged around the center of the substrate; And / or, the position on the substrate corresponding to the polarization zone is hollowed out; And / or, the substrate is a disc substrate; And / or, the laser rangefinder further comprises an electric control unit, and the electric control unit is used for driving each of the polarization elements to rotate so as to select a polarization zone of the polarization element to be located in the optical path where the first ranging laser is located.

6. The laser rangefinder according to claim 4, characterized in that: The at least one polarization element comprises a coated mirror, a grating and a wave plate arranged in sequence along the light transmission direction; wherein, The plurality of polarization zones corresponding to the coated mirror are a plurality of sub-coated mirrors; The multiple polarization regions corresponding to the grating are multiple sub-gratings; The multiple polarization zones corresponding to the wave plate are multiple sub-wave plates.

7. The laser rangefinder according to claim 1, characterized in that: The first lens group includes a first lens, an optical path changing element and a second lens, wherein the second ranging laser is emitted to the optical path changing element through the first lens, is incident to the second lens after the optical path is changed by the optical path changing element, and is emitted to the target through the second lens.

8. The laser rangefinder according to claim 7, characterized in that: The second lens is the objective lens in the visual system, and the optical path changing element includes a first optical path changing element and a second optical path changing element, wherein the second optical path changing element is the second prism in the visual system, and the first optical path changing element is a first reflector or a second prism. The second ranging laser emitted by the first lens is incident on the first prism in the visual system through the first optical path changing element, and is emitted to the target after passing through the first prism and the objective lens in sequence.

9. The laser rangefinder according to claim 1, characterized in that: The laser receiving system comprises a second lens group and a detector, wherein the detector is provided with a photosensitive surface, and the echo laser is incident on the photosensitive surface of the detector through the second lens group.

10. The laser rangefinder according to claim 9, characterized in that: The laser receiving system also includes a second reflector, and the echo laser emitted by the second lens group is incident on the photosensitive surface of the detector through the second reflector.

11. The laser rangefinder according to claim 1, characterized in that: The visual system includes an objective lens, an eyepiece, a first prism and a display screen, wherein the first prism is arranged between the objective lens and the eyepiece, and the display screen is arranged at the object focus of the eyepiece.

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