Lidar

Abstract

The application provides a laser radar, which comprises a laser emission unit and a laser detection unit, the laser emission unit comprises an FB laser and a collimating optical lens group, and the laser detection unit comprises a photoelectric conversion module and a condensing optical lens group; the FB laser comprises a chip support seat and an FB laser chip installed on the chip support seat; a light elimination element is arranged on the non-light-emitting surface of the FB laser chip or the chip support seat close to the non-light-emitting surface of the FB laser chip, and the light elimination element is used for preventing laser from being emitted from the non-light-emitting surface of the FB laser chip. Thus, by arranging the light elimination element on the non-light-emitting surface of the FB laser chip or the chip support seat close to the non-light-emitting surface of the FB laser chip, the "stray light" formed around the main light beam by the reflection and collimation of the light leaked from the non-light-emitting surface after encapsulation can be eliminated, and the detection precision of the laser radar is provided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of radar detection, and particularly relates to a laser radar. BACKGROUND

[0002] The laser radar is a radar system for realizing environment perception by actively emitting a detection light beam to the surrounding space, has the advantages of low dependence on environment, high detection precision, wide detection range, etc., and is widely applied to the fields of industry, transportation, security and automatic driving, etc., and has been rapidly developed in recent years.

[0003] The light source currently applied to the laser radar is generally a semiconductor laser, which includes an FB laser and a VCSEL laser. The FB laser has a higher light power density than the VCSEL laser, can make the laser radar have a longer detection capability, and is widely applied to the laser radar.

[0004] However, when the FB laser is collimated, the resonant cavity along the optical axis direction of the collimation optical system is too long, which can cause stray light around the main light beam after the light beam in the resonant cavity is collimated, the stray light exceeds the detection range, and the detection precision is affected, thereby restricting the development of the laser radar. SUMMARY

[0005] Embodiments of the present application provide a laser radar to solve the problem of low detection precision of the laser radar.

[0006] In a first aspect, embodiments of the present application provide a laser radar, which comprises a laser emission unit and a laser detection unit, the laser emission unit comprises an FB laser and a collimation optical lens group, and the laser detection unit comprises a photoelectric conversion module and a condensing optical lens group.

[0007] The FB laser comprises a chip support seat and an FB laser chip mounted on the chip support seat, and a light extinction element is arranged on the non-light-emitting surface of the FB laser chip or the chip support seat close to the non-light-emitting surface of the FB laser chip, and the light extinction element is used to prevent the laser from emitting from the non-light-emitting surface of the FB laser chip.

[0008] In a possible implementation manner, the light extinction element is a shielding piece made of a low-reflection material, a low-reflection coating or a low-reflection adhesive layer.

[0009] In a possible implementation manner, the light extinction element is prepared by using non-light-transmitting glue or non-light-transmitting ink.

[0010] In a possible implementation manner, the photoelectric conversion module comprises a photoelectric conversion chip, the photoelectric conversion chip comprises a light-receiving surface and an electrode arranged around the light-receiving surface, a light extinction material layer or a low-reflection material layer is arranged on the electrode, or the electrode is prepared by using a low-reflection material.

[0011] In a possible implementation, the photoelectric conversion module comprises a photoelectric conversion chip, the photoelectric conversion chip comprises a light-receiving surface and an electrode arranged around the light-receiving surface, a field-of-view diaphragm is arranged between the light-receiving surface of the photoelectric conversion chip and the condensing optical lens group, and the aperture D of the field-of-view diaphragm satisfies the condition of D l is:

[0012]

[0013] wherein D len is an effective optical aperture of the condensing optical lens group, f is a focal length of the condensing optical lens group, L is a distance between the field-of-view diaphragm and the light-receiving surface, and D d is a diameter of the light-receiving surface.

[0014] In a possible implementation, when the distance between the field-of-view diaphragm and the light-receiving surface is greater than 0, a light-absorbing material layer or a low-reflection material layer is further arranged on the electrode.

[0015] In a possible implementation, the reflectivity of the aperture side wall of the field-of-view diaphragm is R e satisfies the condition of:

[0016] R e th;

[0017]

[0018] wherein R th is the maximum reflectivity allowed by the electrode, I th is the maximum current allowed by the laser detection unit to generate stray light, P k1 is the peak optical power of the condensing optical lens group after convergence and hitting on the electrode, G is the gain of the photoelectric conversion chip, and a is the proportion of the optical power entering the light-receiving surface after reflection by the electrode to the total optical power reflected by the electrode.

[0019] In a possible implementation, the axis of the field-of-view diaphragm is coaxial with the optical axis of the condensing optical lens group, and the side wall of the field-of-view diaphragm forms an angle θ with the axis, wherein θ satisfies the condition of:

[0020]

[0021] wherein D len is an effective optical aperture of the condensing optical lens group, and f is a focal length of the condensing optical lens group.

[0022] In a possible implementation, the lens surface of the collimating optical lens group is provided with an anti-reflection film, and / or the lens surface of the condensing optical lens group is provided with an anti-reflection film.

[0023] In a possible implementation, the anti-reflection film is a multi-period DBR film.

[0024] The embodiment of the present application provides a laser radar, by arranging the light elimination element on the non-light emitting surface of the FB laser chip or the chip support seat close to the non-light emitting surface of the FB laser chip, the light elimination element can be used for preventing the laser from emitting from the non-light emitting surface of the FB laser chip. Therefore, by arranging the light elimination element on the non-light emitting surface of the FB laser chip or the chip support seat close to the non-light emitting surface of the FB laser chip, the stray light formed by the light leakage of the non-light emitting surface of the FB laser chip into the collimating optical lens group beyond the detection range can be eliminated, and the detection precision is improved. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0026] Figure 1 FIG. 1 is a structural schematic diagram of the FB laser provided by the embodiment of the present application;

[0027] Figure 2 FIG. 2 is a light emitting mode of the FB laser provided by the embodiment of the present application;

[0028] Figure 3 FIG. 3 is a structural schematic diagram of the photoelectric conversion module provided by the embodiment of the present application;

[0029] Figure 4a FIG. 4 is an optical path diagram when the distance between the field stop and the photosensitive surface of the photoelectric conversion chip is greater than 0, provided by the embodiment of the present application;

[0030] Figure 4b FIG. 5 is an optical path diagram when the distance between the field stop and the photosensitive surface of the photoelectric conversion chip is equal to 0, provided by the embodiment of the present application;

[0031] Figure 5 FIG. 6 is a structural schematic diagram of the angle between the side wall of the field stop and the axis thereof, provided by the embodiment of the present application. DETAILED DESCRIPTION

[0032] In the following description, specific details are set forth such as particular system configurations, techniques, etc. in order to provide a thorough understanding of the embodiments of the present application. However, it will be apparent to those skilled in the art that the present application can be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present application with unnecessary detail.

[0033] In order to make the objects, technical solutions and advantages of the present application clearer, the following will be described with specific embodiments in conjunction with the accompanying drawings.

[0034] The light emitting direction of a vertical cavity surface emitting laser (VCSEL) is a laser whose light emitting surface is the upper surface and the light emitting direction is perpendicular to the top surface or substrate. The light emitting direction of a feedback laser (FB) is a laser whose light emitting surface is the side surface and the light emitting direction is parallel to the top surface or substrate.

[0035] As described in the background, when the FB laser is collimated, the resonant cavity in the direction of the optical axis of the collimating optical system is too long, resulting in light leakage from the non-light emitting surface of the resonant cavity and the laser. After being reflected and collimated, the "stray light" beyond the detection range is formed around the main light beam, which causes the superposition of different distance detection signals at the receiving end of the laser radar, and has a great influence on the detection accuracy.

[0036] In order to solve the problems in the prior art, the present application provides a laser radar, which will be described below.

[0037] A laser radar includes a laser emitting unit and a laser detecting unit. The laser emitting unit includes an FB laser and a collimating optical lens group. The laser detecting unit includes a photoelectric conversion module and a condensing optical lens group.

[0038] As shown in Figure 1 , the FB laser 10 includes a chip support seat 110 and an FB laser chip 120 mounted on the chip support seat 110. In addition to the supporting function, the chip support seat 110 can also provide protection and electrical connection for the FB laser chip 120.

[0039] As shown in Figure 2 , the light emitting surface 121 of the FB laser chip 120 is Figure 1 the black part, the non-light emitting surface is the back surface opposite to the light emitting surface 121, and the two side walls, all of which are non-light emitting surfaces. A light elimination element is arranged on the non-light emitting surface of the FB laser chip 120 or the chip support seat 110 close to the non-light emitting surface of the FB laser chip 120, and the light elimination element is used to prevent the laser from emitting from the non-light emitting surface of the FB laser chip 120.

[0040] By setting the light-absorbing element on the non-light-emitting surface of the FB laser chip 120, the stray light formed around the main light beam by the reflection and collimation of the leaked light on the non-light-emitting surface can be eliminated. Alternatively, by setting the light-absorbing element on the chip support seat 110 near the non-light-emitting surface of the FB laser chip 120, the stray light formed around the main light beam by the reflection and collimation of the leaked light on the non-light-emitting surface can also be eliminated, thereby improving the detection accuracy of the laser radar.

[0041] In some embodiments, the light-absorbing element can be a shielding piece made of a low-reflectivity material, a low-reflectivity coating, or a low-reflectivity adhesive layer. The size of the shielding piece, the low-reflectivity coating, or the low-reflectivity adhesive layer is not less than the size of the non-light-emitting surface, so that the leaked light emitted by the non-light-emitting surface cannot be emitted.

[0042] In this embodiment, the light-absorbing element can be made of opaque glue or opaque ink.

[0043] For example, a low-reflectivity coating, a low-reflectivity adhesive layer, or a shielding piece can be set on the non-light-emitting surface of the FB laser chip.

[0044] In addition, in order to further improve the detection accuracy of the laser radar, a light-absorbing element, referred to as a second light-absorbing element herein for the sake of distinction, can also be set in the laser detection unit. The second light-absorbing element is used to limit the field of view of the laser radar detection unit to eliminate the influence of interference light outside the field of view on the detection signal.

[0045] As shown in FIG. 1, the light-absorbing element is set on the non-light-emitting surface of the FB laser chip 120. Figure 3 As shown in FIG. 2, the photoelectric conversion module 20 in the laser detection unit includes a photoelectric conversion chip 210 on a photoelectric conversion protection seat 220. Figure 3 As shown in FIG. 3, the photoelectric conversion chip 210 includes a light-receiving surface 211 and an electrode 212 arranged around the light-receiving surface. The electrode 212 around the light-receiving surface 211 has a high reflectivity. When a light beam beyond the field of view hits the electrode, the light beam is reflected by the electrode and undergoes multiple reflections inside the package before being detected by the detector, thereby affecting the detection accuracy.

[0046] Therefore, the second light-absorbing element can be set on the photoelectric conversion chip 210, or between the light-receiving surface 211 of the photoelectric conversion chip and the condensing optical lens group.

[0047] In some embodiments, a light-absorbing material layer or a low-reflectivity material layer can be disposed on the electrode 212 of the photoelectric conversion chip 210, or the electrode 212 can be made of a low-reflectivity material. In this way, the reflectivity of the electrode can be reduced, the light beam hitting the electrode can be reduced, and the influence of the electrode of the photoelectric conversion chip on the detection accuracy can be minimized.

[0048] In some embodiments, a field stop 213 can also be disposed between the light-sensitive surface of the photoelectric conversion chip and the condensing optical lens group, which can also isolate the light beam of the angle outside the field of view.

[0049] In this embodiment, the aperture of the field stop 213 can be adjusted to isolate the light beam of the angle outside the field of view.

[0050] The aperture D of the field stop 213 l is:

[0051]

[0052] wherein D len is the effective optical aperture of the condensing optical lens group, f is the focal length of the condensing optical lens group, L is the distance between the field stop and the light-sensitive surface, and D d is the diameter of the light-sensitive surface.

[0053] As shown in Figure 4a and 4b , the solid line in Figure 4a shows the light path when the distance between the field stop 213 and the light-sensitive surface 211 is greater than 0, Figure 4b shows the light path when the distance between the field stop 213 and the light-sensitive surface 211 is equal to 0, Figure 4a and 4b the dashed line is the light path passing through the electrode 212.

[0054] As can be seen from Figure 4a , when the distance between the field stop 213 and the light-sensitive surface 211 is greater than 0, part of the interference light beam exceeding the field of view will hit the electrode 212 and also form an interference light beam. Therefore, in order to further eliminate the interference light beam, a light-absorbing material layer or a low-reflectivity material layer can also be disposed on the electrode 212.

[0055] In some embodiments, the reflectivity of the aperture side wall of the field stop 213 can also be set to further eliminate the interference light.

[0056] The reflectivity of the aperture side wall of the field stop 213 is R e , and R e satisfies the condition:

[0057] R e <R th ;

[0058]

[0059] Among them, R th I is the maximum allowable reflectivity of the electrode. th P is the maximum current allowed to be generated by stray light in the laser detection unit. k1 G represents the peak optical power that hits the electrode after being focused by the condenser lens group, G is the gain of the photoelectric conversion chip, and α is the ratio of the optical power entering the photosensitive surface after being reflected by the electrode to the total optical power reflected by the electrode.

[0060] In some embodiments, the axis of the field stop 213 is coaxial with the optical axis of the condenser lens group. Furthermore, by setting the angle between the sidewall of the field stop 213 and its axis, interference light can be further eliminated.

[0061] like Figure 5 As shown, the sidewall of the field stop 213 forms an angle θ with its axis, where θ satisfies the following condition:

[0062]

[0063] Among them, D len denoted as , where is the effective optical aperture of the condenser lens group, and f is the focal length of the condenser lens group.

[0064] In some embodiments, in order to reduce multiple reflections between the lens elements of the collimating optical lens group and the FB laser 10, an anti-reflection coating may be provided on the lens surface of the collimating optical lens group.

[0065] In this embodiment, the antireflective film can be a multi-period DBR film, which is a film layer with alternating high and low refractive indices and a thickness of one-quarter wavelength.

[0066] In some embodiments, in order to reduce multiple reflections between the lens element of the condensing optical lens group and the photoelectric conversion chip 210, an anti-reflection coating may also be provided on the lens surface of the condensing optical lens group.

[0067] In this embodiment, the antireflective film can also be a multi-period DBR film, which is a film layer with alternating high and low refractive indices and a thickness of one-quarter wavelength.

[0068] The application eliminates the stray light formed by the light leakage of the non-light-out surface of the FB laser chip into the collimating optical lens group beyond the detection range. In addition, a second light elimination element can be arranged in the photoelectric conversion module. The second light elimination element can be a light elimination material layer arranged on the electrode of the photoelectric conversion chip, or the electrode made of a material with low reflectivity, or a field of view diaphragm arranged between the light-sensitive surface of the photoelectric conversion chip and the condensing optical lens group, which can eliminate the influence of the interference light outside the field of view on the detection signal.

[0069] It should be understood that the size of the serial number of each step in the above-mentioned embodiments does not mean the order of execution, and the execution order of each process should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of the application.

[0070] The above-described embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can still be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. A laser radar comprising a laser emission unit and a laser detection unit, the laser emission unit comprising an FB laser and a collimating optical lens group, and the laser detection unit comprising a photoelectric conversion module and a condensing optical lens group; characterized in that: the FB laser comprises a chip support seat and an FB laser chip mounted on the chip support seat, and a light elimination element is arranged on the chip support seat near or on a non-light-emitting surface of the FB laser chip, the light elimination element being used to prevent laser from being emitted from the non-light-emitting surface of the FB laser chip; the light elimination element is a shielding piece made of a low-reflection material, a low-reflection coating or a low-reflection adhesive layer. The light elimination element is prepared from light-proof glue or light-proof ink. The photoelectric conversion module comprises a photoelectric conversion chip, the photoelectric conversion chip comprises a photosensitive surface and an electrode arranged around the photosensitive surface, a field-of-view diaphragm is arranged between the photosensitive surface of the photoelectric conversion chip and the condensing optical lens group, and the aperture D of the field-of-view diaphragm is: l D = 2 * (R + r) ； wherein is an effective optical aperture of the condensing optical lens group, is a focal length of the condensing optical lens group, is a distance between the field stop and the photosurface, is a diameter of the photosurface.

2. The lidar of claim 1, wherein, The photoelectric conversion module comprises a photoelectric conversion chip, the photoelectric conversion chip comprising a light-receiving surface and an electrode arranged around the light-receiving surface, and a light elimination material layer or a low-reflection material layer is arranged on the electrode, or the electrode is prepared from a low-reflection material.

3. The lidar of claim 2, wherein, When the distance between the field stop and the light-receiving surface is greater than 0, a light elimination material layer or a low-reflection material layer is further arranged on the electrode.

4. The lidar of claim 1, wherein, The lens surface of the collimating optical lens group is provided with an anti-reflection film, and / or the lens surface of the condensing optical lens group is provided with an anti-reflection film.

5. The lidar of claim 1, wherein, The anti-reflection film is a multi-period DBR film.

6. The lidar of claim 1, wherein, The reflectivity of the aperture sidewall of the field stop is R e , R e satisfies the condition that: ； ； wherein, the maximum reflectivity allowed for the electrode, the maximum current allowed for the laser probe unit to generate stray light, the peak optical power hitting the electrode after being focused by the optical lens group, G is the gain of the photoelectric conversion chip, the proportion of the optical power entering the photosensitive surface after being reflected by the electrode to the total optical power reflected by the electrode.

7. The lidar of claim 1, wherein, The axis of the field stop is coaxial with the optical axis of the condenser optical lens group, and the side wall of the field stop forms an angle with the axis thereof wherein The condition is satisfied: ； wherein is an effective optical aperture of the condenser optical lens group, is a focal length of the condenser optical lens group.

8. The lidar of claim 1, wherein, ​ 9. The lidar of claim 8, wherein, ​

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