A laser range finder based on light path folding

Abstract

The utility model discloses a kind of laser range finder based on light path fold, including shell, with transmitting cavity and receiving cavity in it, the transmitting cavity is in the shape of "L", and the receiving cavity is in-line structure;Laser, reflector and collimating lens arranged in the transmitting cavity, the reflector is arranged between the laser and the collimating lens and is set to 45° inclination;Filter, receiving lens group and detector arranged in the receiving cavity, the receiving lens group is arranged between the filter and the detector;The utility model is through the setting of the shape of "L" transmitting cavity and reflector, 90° fold is carried out to transmitting laser light path, so that laser is transversely arranged, and longitudinal space occupancy is reduced by more than 40%;By placing filter in front of receiving lens group front side, the edge signal light cutoff problem caused by filter center wavelength drift is solved, and signal-to-noise ratio is effectively improved.

Description

Technical Field

[0001] This utility model relates to the field of photoelectric measurement technology, and in particular to a laser rangefinder based on optical path deflection. Background Technology

[0002] Existing handheld laser rangefinders mostly use a direct-fire optical path, requiring a longitudinal space of more than 20mm in the housing, resulting in a bulky product. Some solutions add a reflector at the receiver to compress the light, but this still requires additional housing thickness, and the filter is located behind the lens, causing the signal light incident angle at the edge of the field of view to be too large and easily blocked by the filter. Therefore, a new optomechanical structure with a compact structure, reliable assembly, and high signal-to-noise ratio is needed. Utility Model Content

[0003] The main objective of this invention is to provide a laser rangefinder based on optical path refracting, aiming to solve existing technical problems.

[0004] To achieve the above objectives, this utility model provides a laser rangefinder based on optical path refracting, comprising: The housing has an internal transmitting cavity and a receiving cavity, and a transmitting window and a receiving window on its surface. The transmitting cavity is L-shaped, and the receiving cavity has a straight-line structure. A laser, a reflector, and a collimating lens are disposed within the emission cavity. The collimating lens is disposed within the emission cavity and near one end of the emission window. The laser is disposed at the other end of the emission cavity. The reflector is disposed between the laser and the collimating lens and is tilted at 45°. A filter, a receiving lens group, and a detector are disposed within the receiving cavity. The filter is disposed within the receiving cavity and near one end of the receiving window. The detector is disposed at the other end of the receiving cavity. The receiving lens group is disposed between the filter and the detector.

[0005] Furthermore, the reflector is bonded to the positioning bevel inside the housing using UV adhesive.

[0006] Furthermore, the reflector is a plane reflector, one side of which is coated with a narrow-band high-reflectivity film.

[0007] Furthermore, the collimating lens is a monolithic plano-convex lens. Furthermore, the receiving lens group includes a plano-convex lens and a meniscus lens, which are respectively attached to the corresponding mounting steps inside the housing.

[0008] Furthermore, the filter is made of black glass and has a narrow-band filter film coated on its surface.

[0009] Furthermore, the detector is a ceramic-encapsulated avalanche photodiode.

[0010] Furthermore, the outer surfaces of the transmitting and receiving windows are flush with the housing, and can be directly exposed or have a protective film applied to them.

[0011] Furthermore, a light-blocking rib is provided between the transmitting cavity and the receiving cavity.

[0012] Furthermore, it also includes a sealing ring, which is fitted into a groove on the outer surface of the housing.

[0013] The beneficial effects of this utility model are reflected in: This invention uses an "L"-shaped emission cavity and a reflector to fold the emitted laser beam path 90°, allowing the laser to be arranged laterally and reducing the vertical space occupied by more than 40%.

[0014] This invention places the filter in front of the receiving lens group, forming a new structure of "filter-condensing lens-detector", which shortens the optical path length to 1 / 3 of the traditional solution. At the same time, it solves the problem of edge signal light cutoff caused by the center wavelength drift of the filter, and cuts off other large-angle stray light and non-signal light at the receiving front end, effectively improving the signal-to-noise ratio. Attached Figure Description

[0015] Figure 1 This is a schematic cross-sectional view of the ultra-short-size laser rangefinder structure based on optical path folding of this utility model; Figure 2 This is an exploded view of the three-dimensional structure of the ultra-short-size laser rangefinder based on optical path folding of this utility model; Figure 3 This is a schematic diagram of the shell structure of this utility model; Figure 4 This utility model Figure 3 Structural cross-sectional diagram; Figure 5 This is a schematic diagram of the assembly of the ultra-short-size laser rangefinder based on optical path folding of this utility model.

[0016] Explanation of reference numerals in the attached figures: 100. Housing; 101. Transmitting cavity; 102. Receiving cavity; 103. Transmitting window; 104. Receiving window; 105. Light-blocking rib; 200. Laser; 201. Reflector; 202. Collimating lens; 300. Filter; 301. Receiving lens group; 3011. Plano-convex lens; 3012. Meniscus lens; 302. Detector; 400. Signal board. Detailed Implementation

[0017] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present utility model, and not all of them. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present utility model.

[0018] Please see Figure 1-5 This utility model provides a laser rangefinder based on optical path folding, including a housing 100. Specifically, the housing 100 is made of aluminum alloy CNC machined and the surface is treated with matte oxidation. It has a transmitting cavity 101 and a receiving cavity 102 inside, and a transmitting window 103 and a receiving window 104 on the surface. The transmitting cavity 101 is L-shaped and the receiving cavity 102 is in a straight structure. A laser 200, a reflector 201, and a collimating lens 202 are disposed in the emission cavity 101. The collimating lens 202 is disposed in the emission cavity 101 and near one end of the emission window 103. The laser 200 is disposed at the other end of the emission cavity 101. The reflector 201 is disposed between the laser 200 and the collimating lens 202 and is tilted at 45°. A filter 300, a receiving lens group 301, and a detector 302 are disposed in the receiving cavity 102. The filter 300 is disposed in the receiving cavity 102 and near one end of the receiving window 104. The detector 302 is disposed at the other end of the receiving cavity 102. The receiving lens group 301 is disposed between the filter 300 and the detector 302.

[0019] This laser rangefinder, through the arrangement of an "L"-shaped emitting cavity and a reflector 201, folds the emitted laser light path by 90°, allowing the laser 200 to be arranged laterally, reducing the vertical space occupied by more than 40%. By placing the filter 300 in front of the receiving lens group 301, a new structure of "filter-focusing lens-detector" is formed, shortening the optical path length to 1 / 3 of the traditional solution. At the same time, it solves the problem of edge signal light cutoff caused by the center wavelength drift of the filter, cutting off other large-angle stray light and non-signal light at the receiving front end, effectively improving the signal-to-noise ratio.

[0020] Specifically, laser 200 is a semiconductor laser diode with a wavelength of 905nm, which outputs narrowband spectral laser power up to 100 watts when operating in pulsed drive mode.

[0021] Specifically, the reflector 201 is bonded to the positioning slope inside the housing 100 with UV adhesive.

[0022] Specifically, mirror 201 is a plane mirror, one side of which is coated with a 905nm narrowband high-reflectivity film. The coating surface parameters are that the reflectivity R at 905 nm is ≥98%, and R is maintained at ≥97% at an incident angle of 45°±1°. Other reflective deflection elements, such as right-angle prisms, metal film reflective prisms, and freeform surface mirrors, can also achieve 90° optical path deflection.

[0023] Specifically, the collimating lens 202 is a monolithic plano-convex lens with its plane facing the laser surface and easy to fix stably on the structural components. It has a focal length of about 19mm, and the light-emitting surface of the laser tube is located at the focal plane of the lens, thus collimating the laser beam transmitted at a large angle into approximately parallel light with a divergence angle of about 7mrad.

[0024] Specifically, the receiving lens group 301 includes a plano-convex lens 3011 and a meniscus lens 3012, which are respectively attached to the corresponding mounting steps inside the housing 100. The entrance pupil diameter of the receiving lens group 301 is 10mm, and the RMS aberration is optimized to 20um, which is smaller than the photosensitive surface size of the detector 302.

[0025] Specifically, filter 300 is made of black glass with a 905nm narrowband filter coating on its surface. Since the material itself blocks visible light, the additional filter coating achieves even higher cutoff, with a minimum OD4. Ultimately, it achieves visible light wavelengths of 400-780nm, an average transmittance T≤0.01%, a full width at half maximum (FWHM) of 15 nm, and a center wavelength drift of ≤2 nm with an incident angle of 0-15°, effectively improving the signal-to-noise ratio of the receiving system.

[0026] Specifically, the detector 302 is a ceramic-encapsulated avalanche photodiode with a photosensitive surface diameter of 200 μm. Combined with the receiving lens group 301, the field of view is approximately 30 mrad.

[0027] Specifically, the outer surfaces of the transmitting window 103 and the receiving window 104 are flush with the housing 100, and can be directly exposed or have a protective film pasted on them.

[0028] The total optical axis length of this laser rangefinder is 12.5mm. The transmitter includes a 180W laser diode in a TO56 package, a 7.5*7.5-1mm reflector 201, and a 7.3mm diameter collimating lens 202. The receiver includes an 11*9-1mm filter 300; a plano-convex + meniscus receiving lens group 301 with a focal length of 9.2mm and an RMS aberration of 20µm; and a detector 302 with a photosensitive surface diameter of 200µm. Ultimately, it achieves a range measurement distance greater than 1200 meters.

[0029] Specifically, the reflector 201 measures 7.5 mm × 7.5 mm × 1 mm, coated with a 905 nm high-reflectivity film, and has a reflectivity greater than 98%. The collimating lens 202 has a diameter of 7.3 mm, and the distance between the collimating lens 202 and the emitting surface of the laser 200 is 18.6 ± 0.05 mm. The filter 300 is made of black glass with a center wavelength of 905 nm, an FWHM of 15 nm, and a distance of 0.3 ± 0.05 mm from the first surface of the receiving lens. The receiving lens group 301 has a focal length of 9.2 mm, an RMS aberration of 20 µm, and a distance of 5.4 ± 0.03 mm from the photosensitive surface of the detector 302. The detector 302 is ceramic-encapsulated, with a photosensitive surface Φ200 µm. After a 1 m drop, the optical axis remains unchanged, and the ranging distance is ≥1200 m.

[0030] In one embodiment, a light-blocking rib 105 is provided between the transmitting cavity 101 and the receiving cavity 102. This arrangement in this embodiment can block crosstalk between transmission and reception, eliminating the need for a separate support and light-blocking sheet, and further reducing the overall size.

[0031] This invention also includes a signal board 400, which is fixed to the bottom of the housing 100 by two M1.4 screws, with the screw posts also serving as EMI grounding. The drive / amplification circuits for the laser 200 and the detector 302 are all arranged on the signal board.

[0032] In one embodiment, a sealing ring 500 is further included, which is fitted into a groove on the outer surface of the housing 100. Specifically, the sealing ring 500 is made of silicone.

[0033] This embodiment is configured in such a way that when the rangefinder is assembled with other structures, it can fill the microscopic gaps between the contact surfaces, prevent moisture from passing through, and avoid water vapor entering the housing 100 and affecting other structural components.

[0034] It should be noted that if the embodiments of this utility model involve directional indicators such as up, down, left, right, front, back, etc., the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture as shown in the attached figure. If the specific posture changes, the directional indicators will also change accordingly.

[0035] Furthermore, if the embodiments of this utility model involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied. Furthermore, "multiple" refers to two or more. Moreover, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent.

[0036] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A laser rangefinder based on optical path deflection, characterized in that: include, The housing (100) has an internal transmitting cavity (101) and a receiving cavity (102), and a surface having a transmitting window (103) and a receiving window (104), wherein the transmitting cavity (101) is "L" shaped and the receiving cavity (102) is in a straight line structure; A laser (200), a reflector (201), and a collimating lens (202) are disposed in the emission cavity (101). The collimating lens (202) is disposed in the emission cavity (101) and near one end of the emission window (103). The laser (200) is disposed at the other end of the emission cavity (101). The reflector (201) is disposed between the laser (200) and the collimating lens (202) and is tilted at 45°. A filter (300), a receiving lens group (301), and a detector (302) are disposed in the receiving cavity (102). The filter (300) is disposed in the receiving cavity (102) and near one end of the receiving window (104). The detector (302) is disposed at the other end of the receiving cavity (102). The receiving lens group (301) is disposed between the filter (300) and the detector (302).

2. A laser rangefinder based on optical path deflection as described in claim 1, characterized in that: The reflector (201) is bonded to the positioning slope inside the housing (100) with UV adhesive.

3. A laser rangefinder based on optical path deflection as described in claim 1, characterized in that: The reflector (201) is a plane reflector with a narrow-band high-reflectivity film coated on one side.

4. A laser rangefinder based on optical path deflection as described in claim 1, characterized in that: The collimating lens (202) is a single plano-convex lens.

5. A laser rangefinder based on optical path deflection as described in claim 1, characterized in that: The receiving lens group (301) includes a plano-convex lens (3011) and a meniscus lens (3012), which are respectively attached to the corresponding mounting steps inside the housing (100).

6. A laser rangefinder based on optical path deflection as described in claim 1, characterized in that: The filter (300) is made of black glass and has a narrow-band filter film coated on its surface.

7. A laser rangefinder based on optical path deflection as described in claim 1, characterized in that: The detector (302) is a ceramic-encapsulated avalanche photodiode.

8. A laser rangefinder based on optical path deflection as described in any one of claims 1-7, characterized in that: The outer surfaces of the transmitting window (103) and receiving window (104) are flush with the housing (100) and can be directly exposed or have a protective film pasted on.

9. A laser rangefinder based on optical path deflection as described in any one of claims 1-7, characterized in that: A light-blocking rib (105) is provided between the transmitting cavity (101) and the receiving cavity (102).

10. A laser rangefinder based on optical path deflection as described in claim 1, characterized in that: It also includes a sealing ring (500) fitted into a groove on the outer surface of the housing (100).

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