Light beam collimation control method and system of VCSEL (Vertical Cavity Surface Emitting Laser) light source

Abstract

The invention relates to the field of light beam control, in particular to a light beam collimation control method and system of a VCSEL light source. The method comprises the following steps: detecting an initial emergent light beam of a VCSEL light source, carrying out periodic tracking sampling, and determining a light beam structure response characteristic; carrying out region offset calculation one by one according to light beam structure response characteristics to obtain offset compensation parameters of different partitions; adjusting the driving current of the light emitting unit based on the offset compensation parameter to obtain a current adjustment parameter; applying the current adjustment parameter to a VCSEL array in real time, and performing collimation stability evaluation to obtain a stability coefficient; and performing evaluation based on the stability coefficient, and when it is judged that the VCSEL light beam enters a stable collimation state, recording the current adjustment parameter as a collimation adjustment parameter, and entering a low-disturbance maintenance mode. According to the invention, the driving current parameters of the light source are precisely regulated and controlled, so that the light beam collimation precision, stability and anti-disturbance capability are improved.

Description

Technical Field

[0001] This invention relates to the field of beam control, and more particularly to a beam collimation control method and system for a VCSEL light source. Background Technology

[0002] Compared to traditional edge-emitting lasers, VCSELs, while possessing better beam circular symmetry and a smaller divergence angle, are still susceptible to problems such as variations in chip structure inhomogeneity, array unit differences, drive current fluctuations, and temperature changes. These factors can easily lead to variations in beam divergence angle, center shift, and uneven energy distribution. Particularly in VCSEL array applications, the response differences between different emitting units further amplify the inconsistencies in beam spatial distribution, reducing the overall beam collimation accuracy and stability, and impacting the system's imaging quality, ranging accuracy, and signal transmission reliability. During long-term operation of the VCSEL light source, the beam collimation state may drift over time due to accumulated thermal effects, device aging, and changes in the external environment, making it difficult to maintain the initial collimation effect over the long term. If these collimation instabilities are not corrected in time, they will not only reduce the overall performance of the optical system but may also trigger a series of chain reactions such as decreased energy utilization and increased beam distortion, potentially even affecting the normal operation and lifespan of the entire system. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention proposes a beam collimation control method and system for a VCSEL light source, thereby resolving at least one of the aforementioned technical problems.

[0004] To achieve the above objectives, the present invention provides a beam collimation control method for a VCSEL light source, comprising the following steps: Step S1: Detect the initial emitted beam of the VCSEL light source, perform periodic tracking sampling, and determine the beam structure response characteristics; Step S2: Perform offset calculations for each region based on the beam structure response characteristics to obtain offset compensation parameters for different zones; Step S3: Adjust the driving current of the light-emitting unit based on the offset compensation parameters to obtain the current adjustment parameters; Step S4: Apply the current adjustment parameters to the VCSEL array in real time and perform collimation stability evaluation to obtain the stability coefficient; Step S5: Based on the stability coefficient, an evaluation is performed. When it is determined that the VCSEL beam has entered a stable collimation state, the current adjustment parameter is recorded as the collimation adjustment parameter, and the low disturbance maintenance mode is entered.

[0005] This specification provides a beam collimation control system for a VCSEL light source, used to perform the method described above, including: The detection unit is used to detect the initial emitted beam of the VCSEL light source, perform periodic tracking sampling, and determine the beam structure response characteristics. The offset calculation unit is used to perform offset calculations for each region based on the beam structure response characteristics, and obtain offset compensation parameters for different zones. The current adjustment unit is used to adjust the driving current of the light-emitting unit based on the offset compensation parameters to obtain the current adjustment parameters. An evaluation unit is used to apply the current adjustment parameters to the VCSEL array in real time and perform collimation stability evaluation to obtain a stability coefficient. The control unit is used for evaluation based on the stability coefficient. When it is determined that the VCSEL beam has entered a stable collimation state, the current adjustment parameters are recorded as collimation adjustment parameters, and the low disturbance maintenance mode is entered.

[0006] The specific benefits of this invention are as follows: By periodically tracking and sampling the initial emitted beam of the VCSEL light source, information on the structural changes of the beam over time can be continuously acquired, effectively capturing minute fluctuations in the beam's divergence pattern, energy distribution, and center position. This method avoids the limitation of a single static sampling that can only reflect the instantaneous state, allowing the beam's response behavior under conditions of driving current changes, temperature disturbances, and device aging to be fully characterized. Based on the beam's structural response characteristics, offset calculations are performed region by region, refining the originally holistic beam offset problem into offset analysis of multiple local regions, thereby effectively distinguishing the inconsistencies in beam response within different spatial partitions. By calculating the offset for each partition separately and generating corresponding compensation parameters, overcompensation or undercompensation caused by a uniform compensation method can be avoided, making the correction process more precise and controllable. It avoids the complexity brought about by mechanical adjustment or external optical element correction, allowing collimation control to be completed entirely through electrical means, possessing advantages such as fast response speed, good repeatability, and strong integrability. By precisely adjusting the driving current distribution of each light-emitting unit, beam center drift and local divergence anomalies can be effectively suppressed. Quantitative evaluation of alignment stability and generation of a stability coefficient transform the originally qualitative assessment of alignment performance into a clear numerical indicator, thereby improving the objectivity and consistency of alignment state determination. Recording the corresponding current adjustment parameters as alignment adjustment parameters and entering a low-disturbance maintenance mode effectively avoids unnecessary frequent adjustments, thus reducing the impact of driving current fluctuations on beam shape. This helps reduce power consumption variations and thermal disturbance accumulation, improving the alignment maintenance capability of the VCSEL light source during long-term operation. By employing a low-disturbance maintenance strategy in a stable state, the device's lifespan can be extended, ensuring that the beam maintains good alignment performance even when external conditions change slowly. Attached Figure Description

[0007] Figure 1This is a schematic flowchart illustrating the steps of a VCSEL light source beam collimation control method according to the present invention. Figure 2 This is a detailed flowchart illustrating the implementation steps of step S1. Figure 3 This is a flowchart illustrating the detailed implementation steps of step S2. Detailed Implementation

[0008] It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0009] This application provides a method and system for beam collimation control of a VCSEL light source. The execution entities of the VCSEL light source beam collimation control method and system include, but are not limited to, mechanical equipment, data processing platforms, cloud server nodes, network upload devices, etc., which can be considered as general computing nodes in this application. The data processing platform includes, but is not limited to, at least one of an audio-visual management system, an information management system, and a cloud-based data management system.

[0010] Please see Figures 1 to 3 This invention provides a beam collimation control method for a VCSEL light source, comprising the following steps: Step S1: Detect the initial emitted beam of the VCSEL light source, perform periodic tracking sampling, and determine the beam structure response characteristics; Step S2: Perform offset calculations for each region based on the beam structure response characteristics to obtain offset compensation parameters for different zones; Step S3: Adjust the driving current of the light-emitting unit based on the offset compensation parameters to obtain the current adjustment parameters; Step S4: Apply the current adjustment parameters to the VCSEL array in real time and perform collimation stability evaluation to obtain the stability coefficient; Step S5: Based on the stability coefficient, an evaluation is performed. When it is determined that the VCSEL beam has entered a stable collimation state, the current adjustment parameter is recorded as the collimation adjustment parameter, and the low disturbance maintenance mode is entered.

[0011] In the embodiments of the present invention, see Figure 1 The diagram below illustrates the steps of a beam collimation control method for a VCSEL light source according to the present invention. In this example, the steps of the beam collimation control method for the VCSEL light source include: Step S1: Detect the initial emitted beam of the VCSEL light source, perform periodic tracking sampling, and determine the beam structure response characteristics; In this embodiment, during the initial stage of beam collimation control, it is necessary to acquire the emission characteristics of the VCSEL light source and quantify its dynamic response over time. The VCSEL chip is fixed to stabilize the emitted beam direction. A constant current drive is used to set the operating current within 60% to 80% of the rated current (e.g., 6-8mA for a rated 10mA) to ensure stable light output intensity and consistent mode distribution. A high-resolution CCD or CMOS imaging device is used to acquire the light spot image. Near-field light intensity distribution is obtained through microscopic imaging, and far-field light intensity distribution is obtained through lens focal plane imaging. During acquisition, grayscale normalization, background subtraction, and response consistency correction are performed on the image to ensure the quality of the light spot image.

[0012] Periodic sampling is performed within a continuous working time window to acquire the dynamic characteristics of the beam. The time window can be set to 60-120 seconds, and the sampling period can be set between 50-100 milliseconds to ensure the capture of short-term jitter and drift information of the beam spot. For each frame of image, the position of the beam spot centroid, the width of the second moment of the beam spot, and the local energy distribution are calculated to form a temporal sequence of beam spot center and intensity parameters. By segmenting and analyzing the temporal sequence, indicators such as beam energy rearrangement efficiency, main lobe stability recovery capability, and side lobe suppression adaptive trend are extracted to obtain complete beam structure response characteristics.

[0013] Step S2: Perform offset calculations for each region based on the beam structure response characteristics to obtain offset compensation parameters for different zones; In this embodiment, after obtaining the beam structure response characteristics, the beam space is divided into a central main lobe region, a transition diffusion region, and an edge energy leakage region. Using the beam center time-series data and the trends in divergence angle and energy distribution uniformity, the optical axis offset of each beam region is calculated. Specifically, the first moment of the intensity centroid is calculated within each region, and the local centroid is compared with the overall optical axis reference position to obtain the lateral and longitudinal offsets. These offsets are then weighted by the energy proportion within each region to reflect the importance of different regions to the overall beam collimation.

[0014] After the offset calculation is completed, the optical axis offset is mapped to the phase compensation requirements of each zone, generating offset compensation parameters for each zone. The central main lobe region mainly focuses on aligning the beam principal axis, with the offset compensation parameters aiming to align the principal axis; the transition diffusion region focuses on energy balance and beam shape adjustment; and the edge energy leakage region focuses on suppressing peripheral energy diffusion.

[0015] Step S3: Adjust the driving current of the light-emitting unit based on the offset compensation parameters to obtain the current adjustment parameters; In this embodiment, after obtaining the partition offset compensation parameters, they are mapped to the driving current adjustment of each emitting unit in the VCSEL array. Utilizing the beam partitioning and emitting unit matching relationship, the offset compensation parameters for the central main lobe region, the transition diffusion region, and the edge leakage region are allocated to the corresponding emitting unit sets. Based on the VCSEL current-optical power characteristics, the offset compensation amount is converted into the actual driving current adjustment amplitude, generally controlled within ±5% to 15% of the rated current to avoid mode jumps or beam distortion caused by thermal effects. The adjustment strategy differs for different partitions: current fine-tuning of the emitting units in the central main lobe region mainly ensures beam axis alignment and energy concentration; current adjustment in the transition diffusion region is used to balance the energy distribution between the main lobe and the periphery, improving beam shape uniformity; current reduction or redistribution in the edge energy leakage region is used to suppress sidelobes and leaked energy. Through weighted and proportional mapping methods, the partition offset parameters are converted into specific current adjustment values, forming a complete set of current adjustment parameters.

[0016] Step S4: Apply the current adjustment parameters to the VCSEL array in real time and perform collimation stability evaluation to obtain the stability coefficient; In this embodiment, the calculated current adjustment parameters are applied in real time to each light-emitting unit of the VCSEL array, and the current of each unit is independently controlled by a high-speed drive module. Small incremental adjustments are maintained during the application process to avoid introducing new disturbances or changes in the light spot pattern. A high-speed optical acquisition device is used to record the sequence of light spot images. The acquisition frequency is typically set to 50~200Hz to capture short-term dynamic changes in the center position, divergence angle, and main lobe drift of the light spot.

[0017] For each frame of image, the center position and second moment width of the beam are calculated. Based on the changes in the beam center and the amplitude of the divergence angle jitter, the main lobe position drift rate is calculated. The beam center shift, divergence angle jitter, and drift rate are weighted and synthesized to form a collimation stability index, i.e., the stability coefficient. The stability coefficient reflects the dynamic stability of the main lobe position, beam shape, and energy distribution after current adjustment, providing a quantitative basis for judging the beam collimation state.

[0018] Step S5: Based on the stability coefficient, an evaluation is performed. When it is determined that the VCSEL beam has entered a stable collimation state, the current adjustment parameter is recorded as the collimation adjustment parameter, and the low disturbance maintenance mode is entered.

[0019] In this embodiment, the real-time stability coefficient is compared with a preset target collimation index (e.g., 0.95~0.98). When the stability coefficient reaches or exceeds the target threshold, the VCSEL beam is determined to have entered a stable collimation state. At this time, the current adjustment parameters of each light-emitting unit are recorded as collimation adjustment parameters to maintain high-precision beam collimation. After the beam enters the low-disturbance maintenance mode, the VCSEL array maintains the current current state and reduces the spot acquisition frequency to 10~50Hz to reduce the data processing load and reduce beam disturbance.

[0020] If the stability coefficient fails to meet the target, the system initiates an adaptive fine-tuning mechanism, retracing the previous beam image sequence to analyze the source of the offset and making small current adjustments to key light-emitting units (generally within 1% to 5% of the rated current). This process is iterated until the stability coefficient meets the preset target. Through this process, automated closed-loop control of VCSEL array beam collimation is achieved, enabling the beam to quickly converge to a highly stable state under continuous operating conditions, reducing human intervention and beam disturbance.

[0021] In this embodiment, see Figure 2 The diagram below illustrates the detailed implementation steps of step S1. In this embodiment, the detailed implementation steps of step S1 include: The initial emitted beam of the VCSEL light source is detected, and the light intensity distribution of the initial emitted beam is analyzed based on the CCD array to obtain near-field light intensity distribution data and far-field light intensity distribution data. Based on the near-field light intensity distribution data, the beam divergence angle, ellipticity, and spot centroid position are calculated to obtain the near-field light intensity characteristics. Based on the far-field light intensity distribution data, the energy concentration, the surrounding energy ratio, and the edge dispersion coefficient are calculated to generate far-field light intensity characteristics. Based on the near-field and far-field light intensity characteristics, the spatial domain light intensity distribution is transformed to obtain the spatial domain distribution map; Based on the spatial domain distribution map, the standard deviation of the main divergence angle, the energy distribution uniformity index, and the spot center offset are calculated to construct a set of beam characteristic parameters; The beam characteristic parameter set is periodically tracked and sampled within a continuous working time window to determine the beam structure response characteristics.

[0022] In this embodiment, the VCSEL chip is fixed and its emission direction is kept stable. It is driven by a constant current, keeping the operating current within 60% to 80% of the rated current (e.g., 6–8 mA when the rated current is 10 mA) to ensure stable light output intensity and relatively consistent pattern distribution. A high-resolution CCD array is used to sample the emitted beam. The CCD pixel size is approximately 5 μm, and the resolution is set to 1024 × 1024 to meet the requirements for capturing detailed light spots. The near-field light intensity distribution is acquired through imaging, creating a conjugate relationship between the VCSEL emission surface and the CCD photosensitive surface to record the true light intensity distribution on the emission surface. The far-field light intensity distribution is acquired by introducing lenses with a focal length of 100 mm or 200 mm to map the angular distribution of the beam onto the CCD plane. The near-field light intensity image is normalized, and a threshold segmentation method is used to determine the effective light spot area. The threshold is typically selected at 10% or 1 / e² of the maximum light intensity to remove background noise. Within the effective region, the root mean square widths of the light spot in the horizontal and vertical directions are calculated using the second-order moment method. The near-field divergence angle is then calculated based on the pixel size, characterizing the beam's expansion trend at the exit surface. The light spot boundary is elliptical-fitted, and the lengths of the major and minor axes are obtained using the least squares method. The ratio of these lengths is defined as the ellipticity of the light spot, reflecting its symmetry and mode uniformity. Furthermore, the centroid position of the intensity distribution is calculated using the first-order moment, and this position is compared with a reference center to quantify the offset of the light spot center.

[0023] Energy normalization is performed on the far-field intensity data to ensure consistent integrated energy, thereby eliminating the impact of intensity amplitude differences. Then, with the primary emission direction in the far field as the center, a fixed angular range is set, such as ±5° or ±10°, and the proportion of the integrated intensity to the total energy within this range is calculated to obtain an energy concentration index, used to measure whether the beam energy is concentrated in the primary emission direction. For possible ring or multi-ring structures in the far-field spot, the far-field distribution is divided into a central region and several concentric ring regions. The energy proportion of each region is calculated, and the ring energy ratio is defined as the ratio of the outer ring energy to the total energy, used to assess the influence of higher-order transverse modes on the far-field distribution. The intensity variation in the edge region of the far-field spot is analyzed. By calculating the intensity attenuation gradient in the edge region, the edge dispersion coefficient is obtained, used to describe the beam's diffusion characteristics in larger angular directions. Based on the relationship between beam propagation and Fourier transform, the spatial dimension information in the near field and the angular distribution information in the far field are mapped to a unified spatial coordinate framework. Using the near-field spot centroid as the spatial reference origin, propagation distance parameters, such as 10cm, 20cm, or 50cm, are introduced. Combined with the VCSEL's operating wavelength, the far-field angular distribution is converted to the light intensity distribution at the corresponding propagation distance using the angle-to-lateral displacement conversion relationship. The overall size, shape, and orientation of the spatial domain spot are constrained using the near-field divergence angle and ellipticity, thus obtaining a spatial domain light intensity distribution map reflecting the energy expansion and morphological changes of the beam during propagation.

[0024] After obtaining the spatial domain light intensity distribution map, further statistical analysis is performed to construct a set of beam characteristic parameters for beam collimation control. Multiple cross-sectional positions are selected along the main beam propagation direction, and the principal divergence angle at each position is calculated. The results are then statistically processed to obtain the standard deviation of the principal divergence angle, which characterizes the stability and consistency of the beam during propagation. The spatial domain beam spot is divided into several equal-area regions, and the energy in each region is statistically analyzed. The deviation between the energy in each region and the average energy is calculated to obtain an energy distribution uniformity index, used to evaluate the uniformity of the beam energy distribution. Furthermore, by comparing the center position of the spatial domain beam spot with the ideal optical axis position, the beam spot center offset is calculated to quantify the degree to which the beam deviates from the ideal collimation direction.

[0025] In this embodiment, the specific steps for periodically tracking and sampling the beam feature parameter set within a continuous working time window to determine the beam structure response characteristics are as follows: The beam feature parameter set is periodically tracked and sampled within a continuous working time window to obtain a beam feature time sequence; Define the calculation segmentation point; decompose and calculate the beam characteristic time sequence based on the calculation segmentation point, extract the beam energy rearrangement efficiency, main lobe stability recovery capability and side lobe suppression adaptive trend, and obtain the beam structure response characteristics.

[0026] In this embodiment, during beam collimation control, to characterize the dynamic changes in beam characteristics of the VCSEL source under continuous operation, periodic tracking sampling of the constructed beam characteristic parameter set is required within a continuous operating time window. The continuous operating time window can be set to tens of seconds to several minutes, for example, 60s or 120s can be selected as a complete observation window to cover the characteristic changes of the VCSEL during the heat accumulation and drive stabilization phases. Within this time window, the beam characteristic parameter set is sampled at fixed time intervals. The sampling period can be set to 50ms, 100ms, or 200ms to keep the sampling frequency within the range of 5–20Hz, thus balancing time resolution and data stability.

[0027] Each sampling session fully records characteristic parameters such as the standard deviation of the principal divergence angle, energy distribution uniformity index, and beam center offset, and arranges them in chronological order to form a multidimensional beam characteristic time series. During the sampling process, abrupt changes between adjacent sampling points are smoothed out. The influence of transient noise can be reduced through moving averages or exponential weighting, thereby ensuring that the time series data accurately reflects the trend characteristics of beam evolution over time. After obtaining the beam characteristic time series, it needs to be segmented for analysis to extract response characteristics reflecting the beam's structural adjustment and stabilization capabilities. Calculation segmentation points are defined, which can be based on the rate of change of characteristic parameters within a time window or threshold criteria. For example, when the change in the standard deviation of the principal divergence angle or the energy distribution uniformity index exceeds 5% to 10% of its mean, the corresponding time point is used as a calculation segmentation point. In this way, the complete time series is divided into several continuous segments, each segment corresponding to a time interval where beam characteristics are relatively consistent or undergo significant changes.

[0028] Based on segmentation, the characteristic parameters within each segment are decomposed and calculated. By comparing the changes in energy distribution uniformity and energy concentration parameters before and after segmentation, the redistribution efficiency of beam energy between the main lobe and side lobes is evaluated, thus obtaining the beam energy rearrangement efficiency index. By analyzing the time length and amplitude attenuation required for the standard deviation of the main divergence angle to return to the stable region after perturbation, the main lobe stabilization recovery capability is extracted to characterize the self-recovery characteristics of the beam after perturbation. By fitting the changing trends of side lobe-related energy indices within each time segment, the adaptive trend of side lobe suppression over time is obtained, which reflects the response direction and speed of beam structure alignment adjustment.

[0029] In this embodiment, see Figure 3 The diagram below illustrates the detailed implementation steps of step S2. In this embodiment, the detailed implementation steps of step S2 include: Based on the spatial domain distribution map, the beam space is divided into multiple beam partitions; the beam partitions include the central main lobe region, the transition diffusion region, and the edge energy leakage region.

[0030] Based on the beam structure response characteristics, the optical axis offset of each beam partition is calculated by performing region-by-region offset calculations on multiple beam partitions. Based on the optical axis offset, beam leakage suppression calculations are performed to obtain multiple partition phase correction values; Identify the beam control direction of the partition based on the beam structure response characteristics; Based on the phase correction values ​​of multiple zones and the beam control direction, parameter fitting is performed to obtain the offset compensation parameters for different zones.

[0031] In this embodiment, after obtaining the spatial domain intensity distribution map of the beam, the energy distribution structure of the beam in the transverse space is described in detail to provide a basis for zonal control. Using the centroid of the beam spot in the spatial domain distribution map as the reference center, and combining it with the equivalent radius corresponding to the principal divergence angle, a radial analysis of the beam cross-section is performed. By statistically analyzing the cumulative energy percentage within different radius ranges, the beam is divided into multiple spatial zones with clear physical meaning. Typically, the central region with the highest energy percentage and the smallest intensity gradient is defined as the central main lobe region, whose radius can be set to include 60%–70% of the total energy. Outside the central main lobe region, the region where energy gradually decreases and the intensity distribution changes significantly is defined as the transition diffusion region, which generally covers 20%–30% of the total energy. The outermost part with weaker intensity but a larger distribution range is defined as the edge energy leakage region, whose energy percentage is typically less than 10%.

[0032] During the partitioning process, spatial resolution parameters are introduced, such as radial steps of 10 μm or 20 μm, to perform energy integration statistics, ensuring sufficient accuracy and stability at the partition boundaries. This partitioning method, based on energy distribution and spatial location, provides clear control objectives for beam propagation and collimation adjustment in different partitions. After completing the beam spatial partitioning, the degree of offset of each beam partition relative to the ideal propagation direction is evaluated. Using the overall optical axis in the spatial domain distribution map as the reference axis, and combining the aforementioned beam structure response characteristics, the intensity centroid of each partition is calculated independently. First-order moment calculations are performed on the intensity distribution in the central main lobe region, the transition diffusion region, and the edge energy leakage region to obtain the local optical axis position of the corresponding partition. Subsequently, the lateral distance between the local optical axis of each partition and the overall reference optical axis is calculated and converted into angular form using propagation distance parameters (e.g., 20cm or 50cm) to obtain the partition optical axis offset.

[0033] During the calculation, beam energy rearrangement efficiency and main lobe stability recovery capability are incorporated into the weighting factors to correct for the effectiveness of zone offset. For example, when the main lobe recovery capability is weak in a certain time period, the weight of the offset in the transition diffusion region and edge energy leakage region is increased in the overall evaluation to highlight their impact on alignment quality.

[0034] After obtaining the optical axis offset of each beam zone, calculations are performed to suppress the diffusion of beam energy in non-ideal directions. For edge energy leakage regions, the relationship between the optical axis offset and the corresponding energy percentage is analyzed. When the offset exceeds a preset threshold (e.g., 15%–20% of the main lobe divergence angle), the zone is considered to have a significant energy leakage trend. Subsequently, a phase adjustment model is introduced to convert the zone optical axis offset into an equivalent phase compensation requirement, yielding the corresponding phase correction amount. The phase correction amount for the central main lobe region is used as the baseline value, with its correction target focusing on overall optical axis alignment. The phase correction amount for the transition diffusion region is used to smooth the energy transition between the main lobe and the edge. The phase correction amount for the edge energy leakage region is primarily used to reduce energy diffusion in non-main directions. The magnitude of the phase correction amount is related to the zone offset, the zone energy percentage, and the adaptive trend of sidelobe suppression, and is calculated comprehensively through proportional relationships or nonlinear mapping methods.

[0035] After calculating the phase correction for each zone, it is also necessary to determine the control direction of each zone in collimation adjustment to avoid adjustment conflicts between different zones. By analyzing the time evolution direction of the main lobe stabilization recovery capability and the adaptive trend of side lobe suppression in the beam structure response characteristics, the dominant direction of the offset change in each zone can be determined. For example, when the offset of a certain zone shows a monotonically increasing trend over time, its control direction is defined as offset reversal; when the offset shows an oscillating decay trend, the control direction is defined as suppressing oscillations and accelerating convergence.

[0036] Spatially, by comparing the horizontal and vertical components of the optical axis offset vector of each partition, the main offset direction of each partition is determined. This direction is then matched with the changing trend in the structural response characteristics to obtain the partition beam control direction. The central main lobe region typically uses overall optical axis alignment as the main control direction, the transition diffusion region uses energy redistribution balance as the control direction, and the edge energy leakage region uses weakening the energy in the outward expansion and sidelobe directions as the main control direction. After obtaining the phase correction amounts and corresponding beam control directions of multiple partitions, this information is uniformly modeled to generate offset compensation parameters that can be directly used for collimation adjustment. The phase correction amounts of each partition are normalized according to spatial location and energy weights to ensure that the compensation requirements of different partitions are within the same dimension. Subsequently, a parameter fitting method is introduced, using the partition phase correction amounts and partition control directions as input variables, and constructing a partition offset compensation model through polynomial fitting or weighted least squares.

[0037] During the fitting process, the compensation parameters in the central main lobe region have the highest weight to ensure the accuracy of the overall beam direction; the compensation parameters in the transition diffusion region are used to balance the beam shape; and the compensation parameters in the edge energy leakage region are used to suppress energy diffusion in non-dominant directions. By adjusting the fitting order and weighting coefficients, the compensation parameters are made to change continuously and smoothly in space, avoiding abrupt changes that could cause new beam distortions.

[0038] In this embodiment, step S3 includes the following steps: Identify the VCSEL array light-emitting units; The VCSEL array light-emitting units are positioned and matched based on multiple beam partitions, and the matching numbers are marked. Based on the matching number, the driving current adjustment of the light-emitting unit is analyzed using the offset compensation parameters to obtain the current adjustment parameters.

[0039] In this embodiment, the emitting surface of the VCSEL array is identified in two-dimensional space, and each independent light-emitting unit in the array is regarded as a minimum control unit. Based on the structural parameters of the VCSEL array, such as an 8×8 or 16×16 array configuration and a unit spacing of 20μm to 50μm, the relative positions of the light-emitting units in the transverse plane are calibrated. By performing local peak search on the near-field light intensity distribution map, each local light intensity peak is correlated with the position of the light-emitting unit in the array structure, thereby completing the identification of the light-emitting unit.

[0040] During the identification process, overlapping areas of light intensity between adjacent emitting units are distinguished. By setting a minimum spacing threshold or a local contrast threshold, adjacent units are avoided from being misidentified as the same emitting point. Subsequently, a unified reference coordinate system is established based on the array's geometric center, and each emitting unit is assigned a unique spatial coordinate, with numbering rules generated according to row-column or radial order. After completing the identification and numbering of emitting units, they are spatially matched with the previously divided multiple beam partitions to determine the contribution relationship of different emitting units to each beam partition. Using the spatial domain light intensity distribution map as a reference, the spatial boundaries of the central main lobe region, the transition diffusion region, and the edge energy leakage region are mapped back to the VCSEL array's output surface coordinate system. By comparing the positional relationship between the center coordinates of each emitting unit and the boundaries of each beam partition, its main influence area is determined, and it is assigned to the corresponding beam partition.

[0041] During the localization and matching process, the concept of contribution weight is introduced. For emitting units located at the boundary of different zones, a weighted determination is made based on the energy proportion of their emitted light in different zones, thereby avoiding errors caused by simple geometric division. After the zone assignment is completed, each emitting unit is marked with a matching number. This number not only contains its original number information in the array but also its corresponding beam zone category. For example, main lobe zone units, transition zone units, and edge zone units can be distinguished by combining numbers.

[0042] After obtaining the matching numbers of the light-emitting units and beam partitions, the driving current adjustment method of each light-emitting unit is further analyzed based on the offset compensation parameters. The partition offset compensation parameters are mapped to the corresponding light-emitting unit set according to the matching number, so that light-emitting units within the same beam partition share the same or similar compensation trends. Based on this, and combined with the current-optical power characteristic curve of the VCSEL light-emitting unit, the offset compensation amount is converted into an equivalent driving current adjustment requirement. For example, when the driving current range is 2mA to 10mA, the increase or decrease ratio of the current is determined according to the amplitude of the compensation parameters, typically controlled within ±5% to ±15% of the rated current, to avoid introducing new thermal instability factors.

[0043] For the light-emitting units in the central main lobe region, the current adjustment aims to align the overall optical axis and stabilize the main lobe energy, with a relatively small adjustment range. For the light-emitting units in the transition diffusion region, the current distribution is moderately adjusted to balance the energy between the main lobe and the periphery. For the light-emitting units in the edge energy leakage region, the driving current is reduced or redistributed to suppress energy output in non-main directions. By comprehensively considering the stability recovery capability and sidelobe suppression trend in the beam structure response characteristics, the current adjustment amount is refined and corrected to obtain the current adjustment parameter set corresponding to each light-emitting unit.

[0044] In this embodiment, step S4 includes the following steps: The current adjustment parameters are applied to the VCSEL array in real time, the acquisition frequency is defined, and the light spot image sequence is extracted. The center location of the light spot in each frame of the image is calculated based on the light spot image sequence. The amplitude of beam divergence angle jitter and the drift rate of main lobe position are determined based on the beam spot image sequence. The collimation stability is evaluated based on the location of the light spot center, the amplitude of the beam divergence angle jitter, and the drift rate of the main lobe position, and the stability coefficient is obtained.

[0045] In this embodiment, after obtaining the current adjustment parameters of each VCSEL light-emitting unit, they are applied to the VCSEL array in real time to achieve beam offset compensation. The application method typically employs a high-precision constant current drive module to independently adjust the drive current of each unit. The adjustment range is mapped to the current increase / decrease ratio according to the offset compensation parameters, and the amplitude is generally controlled within ±10% of the rated operating current to avoid thermal drift and mode disturbance. The emitted beam spot is dynamically monitored while the current is applied, and a beam spot image sequence is recorded using a high-speed optical acquisition device. The acquisition frequency needs to be set according to the dynamic response characteristics of the beam, generally between 50Hz and 200Hz, to ensure that rapid jitter and drift information of the beam spot can be captured.

[0046] A spot acquisition device typically includes an imaging lens and a CCD or CMOS sensor. The imaging lens maps the light intensity from the VCSEL exit surface or far-field onto the photosensitive device. Each frame of the image undergoes grayscale normalization and background subtraction to eliminate the effects of light source fluctuations and sensor noise. By continuously acquiring thousands of images, a time series of spot images is formed. After acquiring the spot image sequence, center localization analysis is performed on each frame of the spot to quantify the instantaneous shift of the beam direction. The spot center is obtained through first-order moment calculation, i.e., calculating the weighted average position of the pixel light intensity in each frame to obtain the horizontal and vertical coordinates of the spot center. To improve localization accuracy, the spot image can be pre-processed by binarization or Gaussian filtering to remove low-intensity noise and enhance the main spot outline. During the calculation, the center localization accuracy is typically required to reach one-tenth to one-fifth of a single pixel. Combined with the pixel size (5μm to 10μm), micrometer-level center localization accuracy can be achieved.

[0047] Frame-by-frame center localization is performed on the entire image sequence to generate temporal data of the light spot center. This data reflects the minute drift and fluctuation of the light beam over a short time scale. If the light spot has a multi-peak structure, the main light spot can be selected for center calculation during the preprocessing stage using a main peak identification algorithm, ensuring that the localization result reflects the actual offset of the main energy region.

[0048] By utilizing the time-series data of the beam center, the dynamic characteristics of the beam can be further analyzed, including divergence jitter and main lobe position drift rate. The divergence jitter amplitude is obtained by statistically analyzing the range of change in the beam's lateral dimension or second moment width over time. The calculation method involves determining the standard deviation or maximum deviation of the divergence angle over several consecutively acquired frames to quantify the instability of beam spread. The main lobe position drift rate is calculated by taking the first derivative of the change in the beam center coordinates over time, i.e., Δposition / Δtime, typically in micrometers per second or angles per second.

[0049] In the calculation, the time window length can be set, for example, calculating the drift rate every 0.5s or 1s to smooth transient fluctuations and highlight trend changes; filtering is used to reduce the interference of high-frequency noise on the drift rate calculation. The beam collimation stability is comprehensively evaluated based on the spot center positioning, beam divergence angle jitter amplitude, and main lobe position drift rate. The center position offset, divergence angle jitter, and drift rate are weighted and combined to form a stability index. The weights can be set according to the beam control priority; for example, the center main lobe position has the highest weight, followed by the divergence angle, and the drift rate weight is used to quantify short-term dynamic changes. The stability coefficient is normalized to map the comprehensive index to the 0~1 range, where a value closer to 1 indicates higher beam collimation and better stability.

[0050] In practical operation, the stability coefficient can be calculated segment by segment from the acquired light spot sequence of several seconds, and the average value can be calculated over consecutive segments to reduce the impact of transient fluctuations and identify potential system response delays or oscillation problems. This stability coefficient can be used for real-time feedback control to guide the fine-tuning of the VCSEL array drive current, ensuring that the beam maintains high-precision collimation under continuous operating conditions.

[0051] In this embodiment, step S5 includes the following steps: The stability coefficient is compared and evaluated based on the preset target collimation index. When the stability coefficient meets the preset target collimation index, the VCSEL beam is determined to have entered a stable collimation state. The current adjustment parameter is recorded as the collimation adjustment parameter, and the beam enters the low disturbance maintenance mode. When the stability coefficient does not meet the preset target standard index, the current adjustment parameters of the VCSEL array are automatically traced back and fine-tuned for adaptive correction.

[0052] In this embodiment, a preset target alignment index is set according to the actual collimation requirements. For example, the stability coefficient threshold can be set between 0.95 and 0.98, with the value closer to 1 indicating a more stringent requirement for beam stability. The real-time stability coefficient calculated from the continuously acquired beam pattern sequence is compared with this threshold. When the stability coefficient continuously exceeds the preset threshold, it indicates that the beam center position shift, divergence angle jitter, and main lobe drift are all within acceptable ranges, and the beam enters a stable collimation state. At this time, the current adjustment parameters of each VCSEL emitting unit are recorded as collimation adjustment parameters to maintain the high-precision collimation characteristics of the beam.

[0053] After entering the low-disturbance maintenance mode, the VCSEL array maintains the aforementioned current adjustment state, reducing additional adjustment actions and ensuring beam stability during long-term operation. The spot acquisition frequency can be reduced to 10Hz–50Hz to reduce data processing load, monitor minute drift trends, and ensure the beam remains uniformly stable over time. When the stability coefficient fails to meet the preset target straightness index, adaptive backtracking and fine-tuning processing needs to be initiated to actively correct the VCSEL array. The spot image sequence from a previous period is reviewed to identify the main causes of the stability coefficient decrease, including excessive spot center offset, increased main lobe drift rate, or abnormal divergence angle jitter. Based on this information, the emitting units and corresponding beam partitions requiring adjustment are determined. The offset direction and amplitude are then mapped back to the current adjustment amount, and the beam offset is compensated by increasing or decreasing the emitting unit drive current. The current fine-tuning amplitude is typically controlled between 1% and 5% of the rated operating current to achieve smooth correction and avoid introducing new disturbances or mode switching.

[0054] During fine-tuning, the beam spot image sequence and stability coefficient changes are continuously monitored through iterative control, forming a closed-loop adaptive control. After each adjustment, the updated stability coefficient is immediately calculated and compared with the target threshold. If the standard is still not met, fine-tuning continues until the stability coefficient meets the requirements or the maximum number of iterations is reached. Through this real-time adaptive correction method, the VCSEL array can automatically respond to environmental disturbances, device thermal drift, and beam pattern fluctuations, achieving dynamic optimization of beam collimation.

[0055] In this embodiment, a beam collimation control system for a VCSEL light source is provided for performing the method described above, including: The detection unit is used to detect the initial emitted beam of the VCSEL light source, perform periodic tracking sampling, and determine the beam structure response characteristics. The offset calculation unit is used to perform offset calculations for each region based on the beam structure response characteristics, and obtain offset compensation parameters for different zones. The current adjustment unit is used to adjust the driving current of the light-emitting unit based on the offset compensation parameters to obtain the current adjustment parameters. An evaluation unit is used to apply the current adjustment parameters to the VCSEL array in real time and perform collimation stability evaluation to obtain a stability coefficient. The control unit is used for evaluation based on the stability coefficient. When it is determined that the VCSEL beam has entered a stable collimation state, the current adjustment parameters are recorded as collimation adjustment parameters, and the low disturbance maintenance mode is entered.

[0056] Therefore, the embodiments should be considered as exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of the equivalents of the application be incorporated into the invention.

[0057] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement it. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein are implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features of the invention herein.

Claims

1. A method for beam collimation control of a VCSEL light source, characterized in that, Includes the following steps: Step S1: Detect the initial emitted beam of the VCSEL light source, perform periodic tracking sampling, and determine the beam structure response characteristics; Step S2: Perform offset calculations for each region based on the beam structure response characteristics to obtain offset compensation parameters for different zones; Step S3: Adjust the driving current of the light-emitting unit based on the offset compensation parameters to obtain the current adjustment parameters; Step S4: Apply the current adjustment parameters to the VCSEL array in real time and perform collimation stability evaluation to obtain the stability coefficient; Step S5: Based on the stability coefficient, an evaluation is performed. When it is determined that the VCSEL beam has entered a stable collimation state, the current adjustment parameter is recorded as the collimation adjustment parameter, and the low disturbance maintenance mode is entered.

2. The beam collimation control method for the VCSEL light source according to claim 1, characterized in that, The specific steps of step S1 are as follows: The initial emitted beam of the VCSEL light source is detected, and the light intensity distribution of the initial emitted beam is analyzed based on the CCD array to obtain near-field light intensity distribution data and far-field light intensity distribution data. Based on the near-field light intensity distribution data, the beam divergence angle, ellipticity, and spot centroid position are calculated to obtain the near-field light intensity characteristics. Based on the far-field light intensity distribution data, the energy concentration, the surrounding energy ratio, and the edge dispersion coefficient are calculated to generate far-field light intensity characteristics. Based on the near-field and far-field light intensity characteristics, the spatial domain light intensity distribution is transformed to obtain the spatial domain distribution map; Based on the spatial domain distribution map, the standard deviation of the main divergence angle, the energy distribution uniformity index, and the spot center offset are calculated to construct a set of beam characteristic parameters; The beam characteristic parameter set is periodically tracked and sampled within a continuous working time window to determine the beam structure response characteristics.

3. The beam collimation control method for the VCSEL light source according to claim 2, characterized in that, The specific steps for periodically tracking and sampling the beam feature parameter set within a continuous working time window to determine the beam structure response characteristics are as follows: The beam feature parameter set is periodically tracked and sampled within a continuous working time window to obtain a beam feature time sequence; Define the calculation segmentation point; decompose and calculate the beam characteristic time sequence based on the calculation segmentation point, extract the beam energy rearrangement efficiency, main lobe stability recovery capability and side lobe suppression adaptive trend, and obtain the beam structure response characteristics.

4. The beam collimation control method for the VCSEL light source according to claim 1, characterized in that, The specific steps of step S2 are as follows: Based on the spatial domain distribution map, beam space is divided to obtain multiple beam partitions; Based on the beam structure response characteristics, the optical axis offset of each beam partition is calculated by performing region-by-region offset calculations on multiple beam partitions. Based on the optical axis offset, beam leakage suppression calculations are performed to obtain multiple partition phase correction values; Identify the beam control direction of the partition based on the beam structure response characteristics; Based on the phase correction values ​​of multiple zones and the beam control direction, parameter fitting is performed to obtain the offset compensation parameters for different zones.

5. The beam collimation control method for the VCSEL light source according to claim 4, characterized in that, The beam partitioning includes the central main lobe region, the transition diffusion region, and the edge energy leakage region.

6. The beam collimation control method for a VCSEL light source according to claim 1, characterized in that, The specific steps of step S3 are as follows: Identify the VCSEL array light-emitting units; The VCSEL array light-emitting units are positioned and matched based on multiple beam partitions, and the matching numbers are marked. Based on the matching number, the driving current adjustment of the light-emitting unit is analyzed using the offset compensation parameters to obtain the current adjustment parameters.

7. The beam collimation control method for a VCSEL light source according to claim 1, characterized in that, The specific steps of step S4 are as follows: The current adjustment parameters are applied to the VCSEL array in real time, the acquisition frequency is defined, and the light spot image sequence is extracted. The center location of the light spot in each frame of the image is calculated based on the light spot image sequence. The amplitude of beam divergence angle jitter and the drift rate of main lobe position are determined based on the beam spot image sequence. The collimation stability is evaluated based on the location of the light spot center, the amplitude of the beam divergence angle jitter, and the drift rate of the main lobe position, and the stability coefficient is obtained.

8. The beam collimation control method for a VCSEL light source according to claim 1, characterized in that, The specific steps of step S5 are as follows: The stability coefficient is compared and evaluated based on the preset target collimation index. When the stability coefficient meets the preset target collimation index, the VCSEL beam is determined to have entered a stable collimation state. The current adjustment parameter is recorded as the collimation adjustment parameter, and the beam enters the low disturbance maintenance mode. When the stability coefficient does not meet the preset target standard index, the current adjustment parameters of the VCSEL array are automatically traced back and fine-tuned for adaptive correction.

9. A beam collimation control system for a VCSEL light source, characterized in that, The method for performing beam collimation control of the VCSEL light source as described in claim 1 includes: The detection unit is used to detect the initial emitted beam of the VCSEL light source, perform periodic tracking sampling, and determine the beam structure response characteristics. The offset calculation unit is used to perform offset calculations for each region based on the beam structure response characteristics, and obtain the offset compensation parameters for different zones. The current adjustment unit is used to adjust the driving current of the light-emitting unit based on the offset compensation parameters to obtain the current adjustment parameters. An evaluation unit is used to apply the current adjustment parameters to the VCSEL array in real time and perform collimation stability evaluation to obtain a stability coefficient. The control unit is used for evaluation based on the stability coefficient. When it is determined that the VCSEL beam has entered a stable collimation state, the current adjustment parameters are recorded as collimation adjustment parameters, and the low disturbance maintenance mode is entered.

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