A multi-scan-angle parallel phase calibration method for waveguide grating antenna

Abstract

The application discloses a kind of parallel phase calibration methods for waveguide grating antenna of multiple scanning angles, the method includes: the light of one-dimensional waveguide grating antenna exit with M units is received by receiving screen placed in far field, and far field image is photographed using camera;N detection points of different scanning angles are set on far field image;Select one-dimensional waveguide grating antenna arbitrary unit m as control object, to the control voltage of step to make the phase of unit m exit light change from 0 to 2pi, the control voltage corresponding to the maximum energy of detection point at different scanning angles is regarded as the calibration voltage of grating antenna unit m at different scanning angles.The application realizes the parallel calibration of waveguide grating antenna control voltage of different scanning angles by the way of voltage cyclically applied to each waveguide grating antenna, and greatly improves the calibration efficiency of waveguide grating antenna phase.

Description

Technical Field

[0001] This invention belongs to the field of wavefront phase calibration technology, specifically relating to a multi-scan angle parallel phase calibration method for waveguide grating antennas. Background Technology

[0002] LiDAR is a mainstream, cutting-edge technology for accurately and rapidly acquiring three-dimensional images of targets. Currently, mechanical devices such as turntables and rotating mirrors are widely used to achieve laser scanning. This optomechanical system is highly sensitive to temperature and shock, extremely costly, and has a slow scanning speed, limiting its application in both military and civilian fields. Waveguide grating antennas use phased array technology to achieve beam scanning, controlling the direction of light wave propagation by controlling the phase between a large number of small optical antenna elements on the surface.

[0003] However, due to manufacturing defects, there are unavoidable differences in the optical path length between waveguide grating antennas. This results in a randomly distributed and time-constant phase error in the emitted light. Therefore, it is necessary to calibrate the phase of different waveguide grating antenna elements at different scanning angles to avoid the reduction of main lobe energy and the increase of side lobes, or even the fragmentation of the scanning spot, caused by the dispersion of the far-field scanning spot, which would lead to a decrease in detection range and the generation of false alarms.

[0004] Currently, the phase calibration of waveguide grating antennas at different scanning angles mainly uses the quality of the far-field spot at a single angle as the evaluation index and employs an optimization algorithm for iterative optimization. The technical limitation is that the phase of the waveguide grating antenna can only be calibrated at one scanning angle each time, and the iterative optimization algorithm suffers from long calibration time and low calibration efficiency. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention proposes a parallel phase calibration method for waveguide grating antennas with multiple scanning angles. By setting multiple detection points in the far field and cyclically applying voltage to each waveguide grating antenna, parallel calibration of the control voltage for different scanning angles of the waveguide grating antenna is achieved, greatly improving the calibration efficiency of the waveguide grating antenna phase.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A multi-scan angle parallel phase calibration method for waveguide grating antennas, the method comprising: first, light emitted from a one-dimensional waveguide grating antenna having M units is received by a receiving screen placed in the far field, and a camera is used to capture a far field image of the waveguide grating antenna on the receiving screen;

[0008] Then, N detection points with different scanning angles are set on the far-field image captured by the camera. (1≤n≤N);

[0009] Then, an arbitrary element m (1≤m≤M) of the one-dimensional waveguide grating antenna is selected as the control object, and the step size is... The control voltage causes the waveguide phase to change from 0 to 2π, and the detection points at different scanning angles on the far-field image are calculated simultaneously. The energy changes at different scanning angles will be analyzed at the detection points. The control voltage corresponding to the maximum energy is used as the calibration voltage of the grating antenna element m at different scanning angles. ;

[0010] Finally, the above process is performed on all grating antenna elements to obtain the calibration voltage of each grating antenna element at different angles. (1≤n≤N, 1≤m≤M).

[0011] The beneficial effects of this invention are as follows:

[0012] This invention achieves parallel phase calibration of waveguide grating antennas at multiple angles by cyclically applying voltage to each waveguide grating antenna, greatly improving calibration efficiency. It can be used not only for one-dimensional waveguide grating antennas but also for two-dimensional waveguide grating antennas. Attached Figure Description

[0013] Figure 1 This is a flowchart of a multi-scan angle parallel phase calibration method for waveguide grating antennas according to the present invention;

[0014] Figure 2 This is a schematic diagram of an implementation device for a multi-scan angle parallel phase calibration method for waveguide grating antennas according to the present invention;

[0015] Figure 3 This is a schematic diagram of a waveguide grating antenna according to an embodiment of the present invention;

[0016] Figure 4 This is a comparison diagram of the implementation effects before and after the present invention embodiment;

[0017] Figure 5 This is a graph showing the intensity change of the waveguide grating antenna element at the detection point as a function of the control voltage, according to an embodiment of the present invention. Detailed Implementation

[0018] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0019] like Figure 1 The diagram shows a flowchart of a multi-scan angle parallel phase calibration method for a waveguide grating antenna according to the present invention. The method includes: first, light emitted from a one-dimensional waveguide grating antenna with M units is received by a receiving screen placed in the far field, and a camera is used to capture a far field image of the waveguide grating antenna on the receiving screen.

[0020] Then, N detection points with different scanning angles are set on the far-field image captured by the camera. (1≤n≤N);

[0021] Then, an arbitrary element m (1≤m≤M) of the one-dimensional waveguide grating antenna is selected as the control object, and the step size is... The control voltage causes the waveguide phase to change from 0 to 2π, and simultaneously calculates the detection points at different scanning angles on the far-field image. The energy change was observed, and the detection points at different scanning angles were also analyzed. The control voltage corresponding to the maximum energy is used as the calibration voltage U of the grating antenna element m at different scanning angles. nm ;

[0022] Finally, the above process is performed on all grating antenna elements to obtain the calibration voltage of each grating antenna element at different angles. (1≤n≤N, 1≤m≤M).

[0023] like Figure 2 The diagram illustrates the apparatus used in the multi-scanning-angle parallel phase calibration method for waveguide grating antennas according to the present invention: Light emitted from a laser source is input to a fiber optic beamsplitter via an optical fiber. The beamsplitter splits the input light into M paths, providing input light for a one-dimensional waveguide grating antenna with M elements. The emitted light from the waveguide grating antenna propagates through space to reach a far-field receiving screen, forming a far-field spot of the waveguide grating antenna. A camera captures an image of the far-field spot of the waveguide grating antenna, and the image is transmitted back to a computer. The far-field spot is concentrated within a dashed frame on the receiving screen. N detection points are set within the dashed frame, each corresponding to a different scanning angle of the waveguide grating antenna. The computer can send a control voltage signal to a controller, which can independently adjust the phase of the emitted light from each element of the waveguide grating antenna.

[0024] The electric field of the m-th grating antenna element at any point Q in the far field is:

[0025] (1)

[0026] in, Let be the amplitude of the m-th grating antenna element; ω represents the angular frequency; i represents the imaginary unit, and t represents time. Let be the wave vector of the m-th grating antenna element; Let be the position vector of the far-field point relative to the m-th grating antenna element; The initial phase of the m-th grating antenna element; It is the polarization unit vector.

[0027] Since the distance between the far-field point and the waveguide grating antenna is much larger than the aperture of the waveguide grating antenna, and since the light from the waveguide grating antenna comes from the same source, their polarization directions are the same. Therefore, the total electric field at any point Q in the far field can be written as:

[0028] (2)

[0029] When the j-th grating antenna element undergoes a phase change At that time, the intensity (i.e., energy) at any point Q in the far field changes as follows:

[0030] (3)

[0031] Define intermediate parameters , , :

[0032] (4)

[0033] Then the change in Q intensity at any point in the far field is:

[0034] (5)

[0035] As shown in the above formula, by adjusting the phase of the j-th grating antenna element, the intensity at any point Q in the far field exhibits a cosine function variation, and this variation is independent of the intensity changes caused by the phase changes of other antenna elements besides the j-th grating antenna element. Therefore, by sequentially adjusting the phase of each waveguide grating antenna element, an additional phase change that maximizes the intensity at any point Q in the far field can be obtained. The corresponding control voltage is used as the calibration voltage. Furthermore, according to the formula, this law still holds true at points other than any point Q in the far field; that is, the phase change of any waveguide grating antenna element will cause a sinusoidal change in intensity at other points in the far field, independent of other waveguide grating antennas. Therefore, this invention proposes setting multiple detection points in the far field, selecting any element m (1≤m≤M) of the grating antenna as the control object, and using a step size of... The control voltage causes the phase of the emitted light from unit m to change from 0 to 2π, and the detection points at different scanning angles on the far-field image are calculated simultaneously. The energy changes will be observed at different scanning angles. The control voltage corresponding to the maximum energy at the monitoring point is used as the calibration voltage of the grating antenna element m at different angles. Finally, the above process is performed on all grating antenna elements to obtain the calibration voltage of each grating antenna element at different angles. (n=1~N, m=1~M). A multi-threaded approach can be used to perform parallel computation and processing on the intensity change data at each detection point, further improving calibration efficiency.

[0036] Furthermore, the control voltage step size can be adjusted. To obtain calibration voltages of different precision, The smaller the value, the more accurate the calibration.

[0037] Furthermore, a Gaussian function can be used to fit the intensity change at the far-field detection point under different control voltages, and the voltage corresponding to the peak position of the fitted Gaussian function can be used as the calibration voltage to improve the calibration accuracy.

[0038] Furthermore, the method can be applied not only to one-dimensional waveguide grating antennas, but also directly extended to two-dimensional waveguide grating antennas. Each element in the two-dimensional waveguide grating antenna can be operated according to the aforementioned steps.

[0039] Furthermore, this method can use not only the energy change at the detection point as an evaluation index, but also parameters such as peak sidelobe ratio and power in the bucket as evaluation indexes.

[0040] Example

[0041] like Figure 3 As shown in the illustration, this is a specific embodiment of the present invention. The laser source wavelength is 1550 nm, the number of waveguide grating antenna elements is 11, the width w of each element is 1.6 micrometers, the spacing s is 2 micrometers, the length L is 17 micrometers, and the control voltage range is 0 to 5V, corresponding to the variation range of one wavelength for each waveguide grating antenna element. The control voltage step size is... It is 0.25V, corresponding to one-twentieth of a wavelength.

[0042] like Figure 4 As shown, the far-field image before calibration is diffuse. Detection points ①, ②, and ③ are set at -13 degrees, 0 degrees, and 7.8 degrees, respectively. According to the method described in this invention, the far-field image after calibration is obtained. It can be seen from the figure that the energy of the far-field image after calibration is concentrated at the detection point, thus completing the calibration of the waveguide grating antenna at multiple angles.

[0043] Figure 5 The intensity variation curves of the first 5 elements of the waveguide grating antenna at 3 calibration points (i.e., detection points ①, ②, and ③) as a function of control voltage are given. The curves show a sine / cosine function variation.

[0044] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0045] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for parallel phase calibration of waveguide grating antennas with multiple scanning angles, characterized in that, Includes the following steps: The light emitted from a one-dimensional waveguide grating antenna with M grating antenna elements is received by a receiving screen placed in the far field, and a camera is used to capture a far field image of the one-dimensional waveguide grating antenna on the receiving screen. N detection points with different scanning angles are set on the far-field image captured by the camera. , 1≤n≤N; Select any grating antenna element m in the one-dimensional waveguide grating antenna as the controlled object, where 1 ≤ m ≤ M, and take a step size as... The control voltage causes the phase of the emitted light from unit m to change from 0 to 2π, simultaneously calculating the detection points at different scanning angles on the far-field image. The energy at the point is used as an evaluation index to measure the detection points at different scanning angles. The control voltage corresponding to the maximum energy at a given point is used as the calibration voltage of the grating antenna element m at different scanning angles. ; By sequentially controlling all grating antenna elements as the controlled object, voltage-phase control is performed to obtain the calibration voltage of each grating antenna element at different scanning angles.

2. The method for multi-scan angle parallel phase calibration of waveguide grating antennas according to claim 1, characterized in that, The emitted light from the one-dimensional waveguide grating antenna propagates through space to reach the far-field receiving screen, forming a far-field light spot of the one-dimensional waveguide grating antenna. The far-field light spot image of the one-dimensional waveguide grating antenna is captured by a camera.

3. The method for multi-scan angle parallel phase calibration of waveguide grating antennas according to claim 2, characterized in that, The light spot in the far-field light spot image is concentrated within a preset area of ​​the receiving screen, and N detection points are set within the preset area. Each testing point Corresponding to different scanning angles of the waveguide grating antenna, it is used to realize parallel phase calibration of the waveguide grating antenna at multiple scanning angles.

4. The method for parallel phase calibration of waveguide grating antennas with multiple scanning angles according to claim 3, characterized in that, A multi-threaded approach is used for each detection point. The energy change data at the location is processed and computed in parallel.

5. The method for parallel phase calibration of waveguide grating antennas with multiple scanning angles according to claim 1, characterized in that, The phase change of each grating antenna element of the waveguide grating antenna causes a cosine function variation law of energy at detection points at different scanning angles in the far field, and this variation is independent of the energy changes at detection points at different scanning angles in the far field caused by the phase changes of other grating antenna elements (excluding itself).

6. The method for multi-scan angle parallel phase calibration of waveguide grating antennas according to claim 1, characterized in that, By adjusting the control voltage step size To obtain calibration voltages of different precision.

7. The method for parallel phase calibration of waveguide grating antennas with multiple scanning angles according to claim 1, characterized in that, A Gaussian function is used to fit the energy change at the far-field detection point under different control voltages, and the voltage corresponding to the peak position of the fitted Gaussian function is used as the calibration voltage.

8. The method for parallel phase calibration of waveguide grating antennas with multiple scanning angles according to claim 1, characterized in that, The method is applicable to one-dimensional waveguide grating antennas or two-dimensional waveguide grating antennas.

9. A method for parallel phase calibration of waveguide grating antennas with multiple scanning angles according to claim 1, characterized in that, The evaluation metrics also include peak sidelobe ratio and power in the bucket.

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