Dynamic global adjustment exposure method based on germanium-silicon photoelectric detector array

Abstract

The invention belongs to the technical field of photoelectric detection, and particularly relates to a dynamic global adjustment exposure method based on a germanium-silicon photoelectric detector array. Comprising the steps that an n * t germanium-silicon photoelectric detector array is built, and each germanium-silicon photoelectric detector unit serves as an independent pixel point, receives a target optical signal and converts the target optical signal into an initial current signal; each germanium-silicon photoelectric detector unit is externally connected with a trans-impedance amplifier, converts an initial current signal into a voltage signal and performs linear amplification; the output end of each trans-impedance amplifier is connected with a high-speed analog-to-digital converter; processing the amplified voltage signal through a high-speed analog-to-digital converter to obtain a binary discrete digital signal; performing global synchronous sampling to obtain multiple groups of binary discrete data, and superposing the data one by one according to pixel points to generate fusion data; a first frame of initial image is generated, the exposure state is evaluated based on image gray value distribution, and the sampling frequency of the next frame is adjusted during overexposure or underexposure; and the evaluation and adjustment process is repeated to realize adaptive optimization of the detection dynamic range.

Description

Technical Field

[0001] This invention belongs to the field of photoelectric detection technology, and particularly relates to a dynamic global adjustment exposure method based on a germanium-silicon photodetector array. Background Technology

[0002] A photodetector is a device that converts light signals into electrical signals, and it is widely used in optical communication, optical measurement, and photoelectric imaging. The working principle of a photodetector is based on the photoelectric effect, which can be divided into the external photoelectric effect and the internal photoelectric effect. The internal photoelectric effect is the phenomenon where electrons inside an object are emitted outwards from the object's surface under the influence of light. When a metal surface is irradiated by specific light, and the wavelength of the light is less than a certain critical value, the metal absorbs photons and emits photoelectrons. The external photoelectric effect is the phenomenon where light shining on an object causes a change in the object's conductivity or generates a photo-generated electromotive force. In semiconductor materials, when the incident light energy hν ≥ Eg (Eg is the band gap), electrons in the valence band absorb photon energy and jump to the conduction band, forming electron-hole pairs, thereby changing the material's conductivity.

[0003] Traditional photodetectors exhibit significant drawbacks due to their physical mechanisms and performance limitations when dealing with overexposure (incident light power far exceeding the upper limit of the detection range) and underexposure (incident light power below the lower limit of the detection range). These drawbacks directly lead to signal distortion, functional failure, and even device damage.

[0004] The dynamic range (DR) of a photodetector is defined as the ratio of the maximum detectable light power to the minimum detectable light power. The drawbacks of overexposure and underexposure are essentially that the dynamic range cannot cover the actual power variation of the incident light. Summary of the Invention

[0005] To address the problem that traditional photodetectors, due to their single sampling mode, are prone to overexposure and underexposure in environments with drastic exposure changes, leading to signal distortion or even device damage, this invention provides a dynamic global exposure adjustment method based on a germanium-silicon photodetector array.

[0006] The purpose of this invention is to provide a dynamic global adjustment exposure method based on a germanium-silicon photodetector array, specifically including the following steps: S1. Construct an n×t germanium-silicon photodetector array, where n is the number of array columns and t is the number of array rows; each germanium-silicon photodetector unit in the array is used as an independent pixel to receive the target light signal and convert it into an initial current signal; connect an external transimpedance amplifier to each germanium-silicon photodetector unit to convert the initial current signal into a voltage signal and amplify it linearly. S2. Connect a high-speed analog-to-digital converter to the output of each transimpedance amplifier; use the high-speed analog-to-digital converter to sample, hold, quantize, and encode the amplified voltage signal to obtain a binary discrete digital signal; S3. Perform global synchronous sampling on all pixels to obtain the first set of binary discrete data arranged in pixel order; repeatedly sample the same target optical signal using the same global synchronous sampling method to obtain multiple sets of binary discrete data; superimpose the multiple sets of binary discrete data one by one according to the pixels to generate fused data; S4. Generate the first initial image based on the fused data, evaluate the exposure status based on the image grayscale distribution, reduce the number of samples in the next frame if overexposed, and increase the number of samples in the next frame if underexposed; repeat the evaluation and adjustment process to achieve adaptive optimization of the detection dynamic range.

[0007] Preferably, the number of repeated samplings in step S3 is customizable within the range of 1 to 1024 times.

[0008] Preferably, the first group of binary discrete data arranged in pixel order in step S3 is denoted as {x}. ij}, where i represents the row number of the pixel, j represents the column number of the pixel, and x ij This represents the sampled data of the pixel in the i-th row and j-th column, where the value of i is in the range of 1 ≤ i ≤ t, and the value of j is in the range of 1 ≤ j ≤ n.

[0009] Preferably, the second set of binary discrete data obtained by repeated sampling in step S3 is denoted as {y}. ij}, where y ij Let represent the sampled data of the pixel in the i-th row and j-th column, where i ranges from 1 to i to t, and j ranges from 1 to j to n; the fused data after superimposing the two sets of data is {x}. ij +y ij}; The number of repeated samplings is determined based on the power of the target optical signal: when the power of the target optical signal is high, fewer repeated samplings are selected; when the power of the target optical signal is low, more repeated samplings are selected.

[0010] Preferably, the number of repeated samplings is an integer power of 2.

[0011] Preferably, global synchronous sampling is achieved through a synchronous control signal, which simultaneously triggers all germanium-silicon photodetector units, transimpedance amplifiers, and high-speed analog-to-digital converters to ensure that all pixels complete signal acquisition and conversion at the same time.

[0012] Preferably, in step S4, the fused data is the fused data corresponding to 32 samples; the evaluation of exposure status is based on the preset normal range of grayscale values, and grayscale values ​​exceeding the upper limit of the preset normal range are judged as overexposed, and grayscale values ​​below the lower limit of the preset normal range are judged as underexposed.

[0013] Preferably, the amplification factor of the transimpedance amplifier is set according to the initial current signal strength to ensure that the amplified voltage signal meets the acquisition requirements of the high-speed analog-to-digital converter.

[0014] Preferably, the sampling rate of the high-speed analog-to-digital converter is matched with the optical signal response rate of the germanium-silicon photodetector unit to achieve real-time digital conversion of the target optical signal.

[0015] Preferably, in the germanium-silicon photodetector array, the spectral response range of each germanium-silicon photodetector unit is consistent, ensuring consistent response to the same target optical signal.

[0016] Compared with the prior art, the present invention can achieve the following beneficial effects: This invention proposes a method for dynamic global exposure adjustment based on a germanium-silicon photodetector array. Traditional photodetector systems rely on fixed hardware parameters and can only operate stably within a narrow light intensity range. In low light, the signal is easily masked by noise, and in strong light, saturation overexposure is common. This solution utilizes a "multiple global sampling + data overlay" mechanism, expanding the sampling count from 1 to 1024 times as needed. The overlaid binary data covers a wider range of optical power. In low-light scenarios, multiple sampling overlays enhance the effective signal strength and suppress noise interference. In strong light scenarios, reducing the sampling count avoids distortion caused by excessive signal overlay, ultimately achieving customizable and adjustable dynamic range to adapt to various application scenarios from low to high light. A new adaptive adjustment closed loop is added, using the first frame image generated by 32 samples as a baseline. The exposure state is automatically evaluated through grayscale values. Overexposure is automatically reduced, and underexposure is automatically increased, dynamically optimizing the sampling parameters for the next frame and improving the system's response speed and adaptability to changes in light intensity. Attached Figure Description

[0017] Figure 1 This is a flowchart of a dynamic global adjustment exposure method based on a germanium-silicon photodetector array according to an embodiment of the present invention. Detailed Implementation

[0018] In the following description, embodiments of the invention will be described with reference to the accompanying drawings. In the description below, the same modules are denoted by the same reference numerals. Where the same reference numerals are used, their names and functions are also the same. Therefore, their detailed description will not be repeated.

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0020] See Figure 1 The present invention discloses a dynamic global adjustment exposure method based on a germanium-silicon photodetector array, comprising the following steps: S1. Construct an n×t germanium-silicon photodetector array; Where n is the number of array columns and t is the number of array rows, the specific values ​​of n and t can be flexibly set according to the requirements of the detection scenario in practical applications (e.g., 32×32, 64×64, etc.); each germanium-silicon photodetector unit in the germanium-silicon photodetector array is an independent pixel used to receive the target light signal and convert it into an initial current signal; each germanium-silicon photodetector unit has the same spectral response range to ensure consistent response to the same target light signal and avoid signal distortion caused by unit differences; after receiving the target light signal, each germanium-silicon photodetector unit converts the light signal into an initial current signal based on the internal photoelectric effect, and the intensity of the initial current signal is positively correlated with the incident light power; each germanium-silicon photodetector unit is externally connected to a transimpedance amplifier (TIA) to convert the initial current signal into a voltage signal and linearly amplify the voltage signal; Specifically, the amplification factor of the transimpedance amplifier is set according to the strength of the initial current signal to ensure that the amplified voltage signal meets the acquisition requirements of the high-speed analog-to-digital converter. When the target optical signal power is high (strong light scenario), the initial current signal strength output by the germanium-silicon photodetector unit is large. In this case, the amplification factor of the transimpedance amplifier is set to a low value (e.g., 1kΩ-10kΩ) to avoid the amplified voltage signal exceeding the input range of the high-speed analog-to-digital converter, which would cause signal saturation. When the target optical signal power is low (weak light scenario), the initial current signal output by the detector unit is weak. In this case, the amplification factor of the transimpedance amplifier is set to a high value (e.g., 100kΩ-1MΩ). Through linear amplification, the weak voltage signal reaches the effective acquisition threshold of the high-speed analog-to-digital converter, ensuring that the signal can be accurately quantized and encoded.

[0021] Meanwhile, the bandwidth of the transimpedance amplifier is matched with the optical signal response rate of the germanium-silicon photodetector unit to avoid signal distortion due to insufficient bandwidth, ensuring that the amplified voltage signal fully retains the original characteristics of the target optical signal, and providing a reliable signal foundation for subsequent digital conversion and data fusion.

[0022] S2. Connect a high-speed analog-to-digital converter to the output of each transimpedance amplifier. The high-speed analog-to-digital converter samples, holds, quantizes, and encodes the amplified voltage signal to obtain a binary discrete digital signal. Specifically, the sampling rate of the high-speed analog-to-digital converter is matched with the optical signal response rate of the germanium-silicon photodetector unit to achieve real-time digital conversion of the target optical signal; The response rate of a germanium-silicon photodetector unit to a target optical signal is determined by its material properties and structural design, with the corresponding equivalent bandwidth of the target optical signal being the reciprocal of the response time. To ensure real-time capture of the dynamic changes in the target optical signal, the sampling rate of the high-speed analog-to-digital converter (ADC) should be no less than twice the equivalent bandwidth of the target optical signal, and in practical applications, it can preferably be set to 3 to 5 times the equivalent bandwidth of the target optical signal (for example, when the response time is 10 ns, the equivalent bandwidth is 100 MHz, and the sampling rate is set to 300 MHz-500 MHz). This matching design avoids both the loss of high-frequency components and waveform distortion of the optical signal due to excessively low sampling rates, and the waste of hardware resources caused by excessively pursuing high sampling rates, ensuring that sampling efficiency and data accuracy are balanced while achieving real-time digital conversion.

[0023] S3. Perform global synchronous sampling on all pixels to obtain the first set of binary discrete data arranged in pixel order; repeatedly sample the same target optical signal using the same global synchronous sampling method to obtain multiple sets of binary discrete data; superimpose the multiple sets of binary discrete data pixel by pixel to generate fused data; The number of repeated samplings can be customized from 1 to 1024 times, and the number of repeated samplings is an integer power of 2. As the number of samplings increases, the value of the fused data after superposition gradually increases, and the range of optical power that can be covered also expands, thereby realizing the customized expansion of the detection dynamic range.

[0024] Specifically, the first group of binary discrete data arranged in pixel order is denoted as {x}. ij}, where i represents the row number of the pixel, j represents the column number of the pixel, and x ij Let {y} represent the sampled data of the pixel in the i-th row and j-th column, where i ranges from 1 to 1 and j ranges from 1 to 1 and n respectively. The second set of binary discrete data obtained by repeated sampling is denoted as {y}. ij}, where "the second set of binary discrete data" is one of "multiple sets of binary discrete data", y ij Let represent the sampled data of the pixel in the i-th row and j-th column, where i ranges from 1 to 1 and j ranges from 1 to 1 and n respectively; the fused data after superimposing the two sets of data is {x}. ij +y ij}

[0025] In a specific embodiment, the first group of binary discrete data arranged in "row-column" order can be represented as {x 11 x 12 x 13 , ..., x 1n , ..., x 21 x 22 , ..., x tn}, where each data item is uniformly represented by {x ij In summary, 1≤i≤t, 1≤j≤n, where i corresponds to the row number of the pixel, j corresponds to the column number of the pixel, and x... ij This represents the sampled data of the pixel in the i-th row and j-th column. The second set of binary discrete data obtained by repeated sampling is arranged in the same row-column order as {y}. 11 y 12 y 13 , ..., y 1n , ..., y 21 y 22 , ..., y tn All data items are uniformly represented by {y}. ij In summary, where 1≤i≤t, 1≤j≤n, and y ij With x ij The row and column correspondences are completely consistent. When the two sets of data are superimposed one by one according to their corresponding pixels, the principle of "adding data in the same row and column" is followed, and the generated fused data is {x 11 +y 11 x 12 +y 12 x 13 +y 13 , ..., x 1n +y 1n , ..., x 21 +y 21 x 22 +y 22 , ..., x tn +y tn All merged data items are uniformly represented by {x}. ij +y ij In summary, this precise overlay logic of "adding data in the same row and column" ensures that each set of repeated sampled data is perfectly aligned with the first set of data in terms of pixel position, avoiding signal misalignment caused by the mixing and overlay of pixel data from different rows and columns. This is particularly relevant for scenarios where the number of repeated samples is an integer power of 2 (e.g., 4, 8, 16, 32... up to 1024 times). Especially when the number of repeated samplings is an integer power of 2 (such as 4, 8, 16, 32... up to 1024 times), multiple sets of data obtained from subsequent samplings can be superimposed and fused in the same row and column order and alignment principle. This superposition method not only adapts to the core design of custom sampling number, but also enhances the identifiability of weak light signals through the accumulation of multiple sets of data, while avoiding saturation of strong light signals due to excessive superposition. It effectively solves the signal distortion problem under different light intensity environments and improves the accuracy and reliability of detection data.

[0026] S4. Generate the first initial image based on the fused data. Evaluate the exposure status based on the image's grayscale distribution. If overexposed, reduce the number of samples in the next frame; if underexposed, increase the number of samples in the next frame. Repeat the evaluation and adjustment process to achieve adaptive optimization of the detection dynamic range. Specifically: S41. Initial Image Generation: Select the fused data corresponding to 32 samples as the reference data, and reconstruct the reference data according to the row and column order of the pixel array to generate the first frame of the initial image of the system. 32 samples are chosen as the reference because the fused data corresponding to this number of samples can cover the detection requirements of medium light intensity scenes and provide sufficient signal details for exposure evaluation, avoiding evaluation distortion due to too few samples or initial response delay due to too many samples. S42. Dynamic sampling number control: Exposure evaluation is performed based on the gray value distribution of the initial image of the first frame, and a feedback control mechanism is established; if the image is overexposed (gray value exceeds the upper limit of the preset normal range), the sampling number of the next frame is reduced to reduce the signal superposition intensity to suppress overexposure; if the image is underexposed (gray value is lower than the lower limit of the preset normal range), the sampling number of the next frame is increased to enhance the signal superposition intensity to enhance details. In a specific embodiment, the preset normal range of grayscale values ​​is 0-255, where the overexposure threshold is set to 240 and the underexposure threshold is set to 30. The image processor statistically analyzes the grayscale value distribution pixel by pixel: if more than 80% of the pixels in the image have a grayscale value greater than 240, it is determined to be overexposed. At this time, the sampling number of the next frame is reduced (e.g., adjusted from 32 times to 16 times, 8 times, etc.) to reduce the signal superposition intensity and avoid signal saturation distortion; if more than 80% of the pixels in the image have a grayscale value less than 30, it is determined to be underexposed. At this time, the sampling number of the next frame is increased (e.g., adjusted from 32 times to 64 times, 128 times, etc.) to increase the signal superposition intensity and enhance image details; if the proportion of pixels with grayscale values ​​between 30 and 240 exceeds 80%, the sampling number of the next frame remains unchanged.

[0027] S43. Closed-loop optimization implementation: The sampling, data fusion process and image generation and exposure evaluation process are repeatedly executed. The number of samplings for each frame is dynamically adjusted based on the exposure state of the previous frame, forming a continuous closed-loop optimization mechanism. This mechanism ensures that the detection system can adapt to changes in light intensity in real time. Whether it is a scene with strong light, weak light or drastic fluctuations in light intensity, it can output a clear and distortion-free target image.

[0028] In this invention, global synchronous sampling is achieved through a synchronization control signal, generated by a high-precision clock generator. This signal simultaneously triggers all germanium-silicon photodetector units, transimpedance amplifiers, and high-speed analog-to-digital converters, eliminating timing differences among the devices and ensuring that all pixels complete the entire process of target optical signal reception, current-to-voltage conversion, and digital encoding at the same time. This synchronous triggering design ensures that all {x} in the same set of sampled data... ij} or {y ij The corresponding data slices are all from the same time period of the target light signal, avoiding the spatial misalignment of the signal caused by the sampling time difference in traditional pixel / line sampling modes. Especially for dynamically changing target light signals, it can effectively prevent the distortion where "some pixels correspond to the state of the target light signal at the previous moment, and some correspond to the state at the next moment," ensuring the temporal consistency of the data of each pixel. Combined with the spectral response consistency design of each detector unit and the precise stacking logic of the same row and column, the final output fused data can not only realistically restore the spatial distribution of the target light signal, but also accurately retain its dynamic characteristics in the temporal dimension, significantly improving the accuracy and stability of photoelectric detection and imaging.

[0029] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this invention disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this invention can be achieved, and this is not limited herein.

[0030] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A dynamic global adjustment exposure method based on a germanium-silicon photodetector array, characterized in that: Specifically, the following steps are included: S1. Construct an n×t germanium-silicon photodetector array, where n is the number of array columns and t is the number of array rows; each germanium-silicon photodetector unit in the array is used as an independent pixel to receive the target light signal and convert it into an initial current signal; connect an external transimpedance amplifier to each germanium-silicon photodetector unit to convert the initial current signal into a voltage signal and amplify it linearly. S2. Connect a high-speed analog-to-digital converter to the output of each transimpedance amplifier; use the high-speed analog-to-digital converter to sample, hold, quantize, and encode the amplified voltage signal to obtain a binary discrete digital signal; S3. Perform global synchronous sampling on all pixels to obtain the first set of binary discrete data arranged in pixel order; repeatedly sample the same target optical signal using the same global synchronous sampling method to obtain multiple sets of binary discrete data; superimpose the multiple sets of binary discrete data one by one according to the pixels to generate fused data; S4. Generate the first initial image based on the fused data, evaluate the exposure status based on the image grayscale distribution, reduce the number of samples in the next frame if overexposed, and increase the number of samples in the next frame if underexposed; repeat the evaluation and adjustment process to achieve adaptive optimization of the detection dynamic range.

2. The dynamic global adjustment exposure method based on a germanium-silicon photodetector array according to claim 1, characterized in that: The number of repeated samplings in step S3 can be customized within the range of 1 to 1024 times.

3. The dynamic global adjustment exposure method based on a germanium-silicon photodetector array according to claim 1, characterized in that: In step S3, the first group of binary discrete data arranged in pixel order is denoted as {x}. ij }, where i represents the row number of the pixel, j represents the column number of the pixel, and x ij This represents the sampled data of the pixel in the i-th row and j-th column, where the value of i is in the range of 1 ≤ i ≤ t, and the value of j is in the range of 1 ≤ j ≤ n.

4. The dynamic global adjustment exposure method based on a germanium-silicon photodetector array according to claim 3, characterized in that: The second set of binary discrete data obtained by repeated sampling in step S3 is denoted as {y} ij }, where y ij Let represent the sampled data of the pixel in the i-th row and j-th column, where i ranges from 1 to i to t, and j ranges from 1 to j to n; the fused data after superimposing the two sets of data is {x}. ij +y ij }; The number of repeated samplings is determined based on the power of the target optical signal: when the power of the target optical signal is high, fewer repeated samplings are selected; when the power of the target optical signal is low, more repeated samplings are selected.

5. The dynamic global adjustment exposure method based on a germanium-silicon photodetector array according to claim 4, characterized in that: The number of repeated samplings is an integer power of 2.

6. The dynamic global adjustment exposure method based on a germanium-silicon photodetector array according to claim 1, characterized in that: The global synchronous sampling is achieved through a synchronous control signal, which simultaneously triggers all germanium-silicon photodetector units, transimpedance amplifiers, and high-speed analog-to-digital converters to ensure that all pixels complete signal acquisition and conversion at the same time.

7. The dynamic global adjustment exposure method based on a germanium-silicon photodetector array according to claim 1, characterized in that: In step S4, the fused data is the fused data corresponding to 32 samples; the evaluation of exposure status is based on the preset normal range of grayscale values. Grayscale values ​​exceeding the upper limit of the preset normal range are judged as overexposed, and grayscale values ​​below the lower limit of the preset normal range are judged as underexposed.

8. The dynamic global adjustment exposure method based on a germanium-silicon photodetector array according to claim 1, characterized in that: The amplification factor of the transimpedance amplifier is set according to the initial current signal strength to ensure that the amplified voltage signal meets the acquisition requirements of the high-speed analog-to-digital converter.

9. The dynamic global adjustment exposure method based on a germanium-silicon photodetector array according to claim 1, characterized in that: The sampling rate of the high-speed analog-to-digital converter is matched with the optical signal response rate of the germanium-silicon photodetector unit, thereby realizing real-time digital conversion of the target optical signal.

10. The dynamic global adjustment exposure method based on a germanium-silicon photodetector array according to claim 1, characterized in that: In the germanium-silicon photodetector array, each germanium-silicon photodetector unit has the same spectral response range, ensuring consistent response to the same target optical signal.

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