CN105487237B - Optical splitting element, device and method of a multi-beam laser radar - Google Patents

Abstract

the invention relates to a light splitting element, a device and a method of a multi-beam laser radar, belonging to the field of light splitting elements, devices and methods.A light splitting device protected by the invention comprises a laser source, a collimating cylindrical lens and a multi-face cylindrical prism, wherein the laser source and the collimating cylindrical lens form a collimating light path, the light path forms a focused strong spot light spot in a far field, and the multi-face cylindrical prism is the light splitting optical element protected by the invention.

Description

Optical splitting element, device and method of a multi-beam laser radar

technical field

The invention relates to a light splitting element, a device and a method, in particular to a light splitting element, a device and a method of a multi-beam laser radar.

Background technique

Spectroscopic technology is an important type of optical technology. According to optical principles, there are coating spectroscopic, prism spectroscopic, scattering spectroscopic, etc. Different spectroscopic principles have their own characteristics. In the existing lidar laser emitting light path, some divide the light source into two, and some do not divide it but transform it into a line spot to emit. In the lidar that realizes multi-line detection, the receiving part is generally completed by a receiving objective lens, and multiple detection elements are used for detection. Each detection element divides the detected field of view. Since there is a certain gap between each detection element, so There must be a part of the light that enters the receiving lens but is not utilized, so the energy loss of this scheme is serious.

Contents of the invention

In order to overcome the deficiencies of the existing technology, the invention patent has designed a component based on the polyhedral prism refraction beam splitting. Equal partitions. The present invention aims to provide a multi-beam splitting device and method, and the technical solutions are as follows:

A spectroscopic optical element used in a multi-beam laser radar device, comprising: a first spectroscopic unit: a first incident surface of a first body and a first exit surface; the area of the first incident surface is smaller than that of the first exit surface area; the first exit surface is discontinuously adjacent to the first incident surface; the spectroscopic optical element includes two or more first spectroscopic units.

In a preferred manner, the spectroscopic optical element includes four first spectroscopic units, the first incident surface is continuously adjacent to the first incident surface, and the first exit surface is continuously adjacent to the first exit surface; the first incident surface is continuously adjacent to the first exit surface; The vertical heights of an incident surface and the first outgoing surface are greater than the wavelength of the split wave.

In a further preferred manner, the spectroscopic optical element further includes: a second spectroscopic unit: a second body, a second incident surface, and a second exit surface; the area of the second incident surface is equal to the area of the second exit surface ; the second exit surface is discontinuously adjacent to the second incident surface; the spectroscopic optical element includes one or more than one second spectroscopic units.

In a further preferred manner, the light-splitting optical element includes two first light-splitting units and one second light-splitting unit, the first incident surface is respectively adjacent to the second incident surface, and the first outgoing surface is respectively connected to the second light-splitting unit. The second exit surface is continuously adjacent; the spectroscopic optical element includes four first spectroscopic units and one second spectroscopic unit; the second incident surface of the second spectroscopic unit and the first incident surface of the two first spectroscopic units The surfaces are continuously adjacent, the second exit surface is continuously adjacent to the two first exit surfaces; the first incident surfaces of the remaining two first light splitting units are continuously adjacent to the first incident surfaces, and the first exit surfaces are continuously adjacent to the first exit surfaces; The vertical heights of the first incident surface, the first exit surface, the second incident surface and the second exit surface are greater than the wavelength of the split wave.

In a further preferred manner, the first incident surface, the first exit surface, the second incident surface and the second exit surface are all planes.

The present invention also invents a multi-beam lidar spectroscopic device, comprising: a laser light source, a collimating cylindrical lens and a polygonal cylindrical prism; the laser light source and the collimating cylindrical lens form a collimating optical path, and the optical path is A focused strong spot is formed; the polygonal cylindrical prism is any kind of spectroscopic optical element of the above-mentioned multi-beam laser radar.

The present invention also invents a multi-beam laser radar splitting method, which uses the above-mentioned multi-beam laser radar splitting device.

The advantages and positive effects of the present invention are: the light-splitting scheme is easy to realize light-splitting, the cost is low, no process such as a light-splitting film is required, and a high-cost grating light-splitting element is not required, and the structure of the parts adopting the method of the present invention is simple and easy. The present invention overcomes the problem of low energy utilization in the prior art. If the radar needs to split the optical path into N beams, the present invention can realize N beams to be equally divided, and N concentrated light spots will be formed on the detection plane after beam splitting highlights. The separation of beam and radiation energy is realized, and it has the characteristics of high integration and high energy utilization rate. Compared with the prior art, this distribution can save the number of light sources LD and achieve low cost.

Description of drawings

Figure 1 is a schematic diagram of the principle of light splitting;

Fig. 2 is the outline drawing of the spectroscopic optical element;

Fig. 3 is a schematic diagram of Embodiment 1 of four-way splitting in the present invention;

Fig. 4 is a schematic diagram of Embodiment 2 of four-way splitting in the present invention;

Figure 5 shows the far-field irradiance before collimation without splitting;

Figure 6 shows the far-field irradiance of four beams with equal power splitting.

Explanation of reference signs:

1-laser light source, 2, 3-collimating cylindrical lens, 4, 5, 6-splitting optical elements.

Detailed ways

The present invention will be further described in detail below through specific embodiments in conjunction with the accompanying drawings. The following examples are only descriptive, not restrictive, and cannot limit the protection scope of the present invention.

The invention patent designs a spectroscopic part based on polyhedral prism refraction. The design principle is to divide the radiation flux of the light source, especially semiconductor laser or laser diode, into N equal partitions within the solid angle of the emission space.

Φ _i =∫I(θ _x ,θ _y )dΩ _i

In the above formula, it represents the light intensity of the light source in the spatial direction, which is a function of the angle in the horizontal direction and the angle in the vertical direction, and represents the steradian solid angle in the segmented area. The integral of the above formula shows that it is in the divided i-th partition Radiant flux. At the same time, the distribution of light intensity on any plane perpendicular to the emission axis is also a Gaussian distribution, and the distribution of its light intensity can also be described by the following formula:

In the above formula, the coordinate system is established with the laser emission point as the origin, Kx is the reciprocal of the laser divergence angle in the x-axis direction; Ky is the reciprocal of the laser divergence angle in the y-axis direction; θ _x is the deflection angle of the laser along the x-axis direction; θ _y is the deflection angle of the laser along the y-axis; I ₀ is the radiation intensity of the light source along the axis. a1 and a2 are the upper and lower limits of the integral of the deflection angle on the x-axis respectively, and b1 and b2 are the upper and lower limits of the integral of the deflection angle on the y-axis respectively.

The light-splitting optical element of the present invention performs light-splitting based on the physical meaning of the above two formulas, and its light-splitting principle is shown in FIG. 1 .

The incident light is first collimated before entering the spectroscopic optical element, and then enters the spectroscopic optical element from the incident surface. Since the polygonal prism has different deflection angles α, that is, the solid angle facing the light source, the outgoing light is divided into N subdivisions, And these N sub-components point to different angles respectively, and shoot toward the pre-designed direction. The spectroscopic optical element of the present invention can also be regarded as stacked by a plurality of trapezoidal platforms and or one or more regular quadrangular prisms, each trapezoidal platform has a certain height h and deflection angle α, these two structural parameters control each beam splitting of radiation flux. The higher the h, the larger the solid angle facing the light source, and the equal or unequal division of the beam can be realized by adjusting h. The height of h is much larger than the wavelength of the split light wave, so optical elements based on the principle of diffraction are excluded. The deflection angle α is the solid angle facing the light source, and the deflection angle of each N subdivision after beam splitting is determined by the α of each trapezoidal stage. Possible shapes of the spectroscopic optical element are shown in FIG. 2 .

The spectroscopic optical element protected by the present invention is not limited to the shapes described in the embodiments or descriptions of the drawings. The spectroscopic optical element protected by the present invention can split light into two, three, four, five, or more, and split light into equal parts. or unequal.

The specific implementation will be described below by taking the first light-splitting unit as a trapezoidal platform and the second light-splitting unit as a regular square prism as an example.

(1) Embodiment 1

The light-splitting optical element is composed of two first light-splitting units. According to the principle of the above physical formula, the two first light-splitting units with heights h1 and h2 are selected according to the light-splitting requirements to realize the bisection or unequal division of the beam. Select the deflection angles α1 and α2 according to the deflection direction of the outgoing light. The incident surfaces of the two first light-splitting units are continuously adjacent, and the exit surfaces of the two first light-splitting units are continuously adjacent. The beam splitting optics can split the beam into two.

(2) Embodiment 2

The spectroscopic optical element is composed of two first spectroscopic units and a second spectroscopic unit. According to the principle of the above physical formula, two first spectroscopic units and a second spectroscopic unit with heights of h1, h2, and h3 are selected according to the spectroscopic requirements to realize For the equal or unequal division of the beam, the deflection angles α1, α2, and α3 are selected according to the deflection direction of the outgoing light. The incident surfaces of the two first light-splitting units are respectively adjacent to the incident surfaces of the second light-splitting unit, and the exit surfaces of the two light-splitting units are respectively continuously adjacent to the exit surface of the second light-splitting unit 1 . The beam-splitting optical element can realize three-point splitting of the beam.

(3) Embodiment 3

The light-splitting optical element is composed of four first light-splitting units. According to the principle of the above physical formula, four first light-splitting units with heights of h1, h2, h3, and h4 are selected according to the light-splitting requirements to realize quartering or unequal division of the beam . Select deflection angles α1, α2, α3, α4 according to the deflection direction of the outgoing light. The incident surfaces of the four first light-splitting units are continuously adjacent, the exit surfaces of the four first light-splitting units are continuously adjacent, and the four first light-splitting units are symmetrical about the middle ridge line. The beam-splitting optical element can realize the quartering of the light beam.

(4) Embodiment 4

The spectroscopic optical element is used in combination with the elements in Embodiment 1 and Embodiment 2 to achieve 5 beam splitting. When used in combination, the elements in Embodiment 1 are combined with the elements in Embodiment 2, and the connected part is just at the light source in the plane of the optical axis. If the components in Example 1 divide the light source into two equal parts, and the original components in Example 2 divide the light source into three equal parts, then after combined use, the pair of light sources 1/6, 1/6, 1/6, 1/4, 1/4 4 split ratio.

In the present invention, the laser light source LD is quartered by taking the quartering beam splitting optical element as an example, and there are the following two implementation methods. The spectroscopic optical element protected by the present invention is not limited to the shapes described in the embodiments or descriptions of the drawings. The spectroscopic optical element protected by the present invention can split light into two, three, four, five, or more, and split light into equal parts. or unequal.

(5) Embodiment 5

As shown in FIG. 3 , the first method is a four-quadrant method, which includes a laser light source 1 , collimating cylindrical lenses 2 and 3 , and spectroscopic optical elements 4 and 5 . The light source 1 and the collimating cylindrical lenses 2 and 3 form a collimated optical path, which forms a collimated laser beam in the far field. The result is shown in Figure 5. The spectroscopic optical elements 4 and 5 are the combination of the two spectroscopic optical elements described in Embodiment 1, and the two are placed side by side to form a quadrilateral, and the solid angle α of each of these four surfaces facing the light source 1 is equal, and The intersection point of the four surfaces is located on the axis of the light source, and the spectroscopic optical elements 4 and 5 are combined to form four equal-area adjacent first incident surfaces and four equal-area adjacent first exit surfaces, so the light source 1 The emitted power is quartered, and the light splitting effect achieved by this arrangement is to form four bright spots with equal energy in the far field.

(6) Embodiment 6

As shown in FIG. 4 , the spectroscopic device includes a laser light source 1 , collimating cylindrical lenses 2 and 3 and a spectroscopic optical element 6 . The light source 1 and the collimating cylindrical lenses 2 and 3 form a collimated optical path, which forms a collimated laser beam in the far field. The result is shown in Figure 5. The spectroscopic optical element 6 is the spectroscopic optical element described in Embodiment 3, and its spectroscopic surface is composed of four first incident surfaces adjacent to each other, symmetrical with the middle ridge line, h and α of the two spectroscopic units on one side are not equal , the first incident surface close to the optical axis receives strong light, so the h of the light splitting unit is smaller, and the area of the first incident surface is smaller. Therefore, the solid angles α of the four light splitting units facing the light source 1 are also not equal. According to the integral calculation, the light radiant flux of each surface is equal.

Both implementation case 5 and implementation case 6 can achieve the spectroscopic results shown in FIG. 6 .

Claims (6)

1. A spectroscopic optical element used in a multi-beam laser radar device, comprising: The first light splitting unit: a first body, a first incident surface and a first exit surface; the area of the first incident surface is not equal to the area of the first exit surface; the first exit surface is discontinuously adjacent to the first exit surface the first surface of incidence; It is characterized in that the spectroscopic optical element includes two or more first spectroscopic units; the spectroscopic optical element includes a second spectroscopic unit: a second body, a second incident surface and a second exit surface; the second the area of the entrance surface is equal to the area of the second exit surface; the second exit surface is discontinuously adjacent to the second entrance surface; The spectroscopic optical element includes one or more than one second spectroscopic units; The light-splitting optical element includes two first light-splitting units and one second light-splitting unit, the first incident surfaces are respectively adjacent to the second incident surfaces continuously, and the first exit surfaces are respectively connected to the second exit surfaces consecutive adjacency; The height of the first incident surface and the first exit surface in the vertical direction is greater than the wavelength of the split wave; The vertical heights of the first incident surface, the first exit surface, the second incident surface and the second exit surface are greater than the wavelength of the split wave. 2 . The spectroscopic optical element according to claim 1 , wherein the spectroscopic optical element comprises four first spectroscopic units, the first incident surfaces are continuously adjacent, and the first exit surfaces are continuously adjacent. 3 . 3. A spectroscopic optical element according to claim 1, characterized in that, the spectroscopic optical element comprises four first spectroscopic units and a second spectroscopic unit; the second incident surface of the second spectroscopic unit and The first incident surfaces of the two first light-splitting units are continuously adjacent, and the second exit surface is continuously adjacent to the two first exit surfaces; the first incident surfaces of the remaining two first light-splitting units are continuously adjacent to the first incident surface, and the first The exit surface continuously adjoins the first exit surface. 4. The spectroscopic optical element according to any one of claims 1-3, wherein the first incident surface, the first exit surface, the second incident surface and the second exit surface are all planes. 5. A spectroscopic device comprising the multi-beam laser radar of the spectroscopic optical element described in any one of claims 1-4, comprising: a laser light source, a collimating cylindrical lens and a polygonal cylindrical prism; the laser light source and the The collimating cylindrical lens forms a collimating optical path, which forms a focused strong spot in the far field; It is characterized in that the polygonal cylindrical prism is any spectroscopic optical element described in claims 1-4. 6. A spectroscopic method for a multi-beam laser radar, characterized in that the spectroscopic device for a multi-beam laser radar according to claim 5 is used.