A device and method for calibrating fixed phase mode noise of an iToF image sensor

Abstract

This invention relates to a fixed-phase mode noise (FPPN) calibration device and method for iToF image sensors. The invention achieves near-identical light signal flight times for pixels at different positions within a pixel array, and synchronizes the emitter and iToF image sensor in modulation period and emission time via a synchronization line. Furthermore, it simplifies FPPN calibration by ensuring the iToF image sensor falls within the illumination field of the modulated light signal, resulting in low setup and maintenance costs. Calibration accuracy can be improved by increasing the distance between the emitter and the iToF image sensor. Since FPPN calibration is performed before lens installation, the calibration results are independent of the lens calibration results, ensuring accuracy and reliability. Moreover, it eliminates the need to calculate actual distances or construct calibration whiteboards for precise angle and distance control, thus saving calibration costs.

Description

Technical Field

[0001] This invention relates to the field of ToF ranging technology, and in particular to a device and method for calibrating fixed phase mode noise of an iToF image sensor. Background Technology

[0002] Binocular ranging, structured light, and time-of-flight (ToF) are the three mainstream 3D imaging technologies today. Among them, ToF, due to its advantages such as simple principle, simple and stable structure, and long measurement distance, has been gradually applied to fields such as gesture recognition, 3D modeling, autonomous driving, and machine vision. ToF technology is a method for accurately measuring the distance of objects. There are direct-time-of-flight (dToF) ranging technology, which directly measures the flight time of light to calculate the distance of objects, and indirect-time-of-flight (iToF) ranging technology, which calculates the distance of objects by periodically modulating and demodulating the light intensity and using phase information.

[0003] Please refer to the following: Figure 1 , Figure 2 ,in, Figure 1 This is a schematic diagram illustrating the working principle of an iToF camera. Figure 2 This is a schematic diagram of continuous wave modulation ranging. Specifically, the iToF camera controls the emitter 12 to actively emit continuously modulated light pulses as emitted light 13 through the modulator 11. The emitted light 13 is emitted onto the surface of the target object 19, and the reflected light 14 formed after reflection by the target object 19 is sampled and acquired by the demodulator 15. The phase shift between the emitted light 13 and the reflected light 14 is then used to determine the range. It can calculate the depth information of target object 19.

[0004] Since the speed of light c and the modulation frequency f of the emitted light are known quantities, the phase shift can be obtained. Based on this, the depth d of the target object can be obtained using the following formula:

[0005]

[0006] For iToF technology, due to its inherent imaging characteristics and external environmental interference, the directly acquired data usually contains certain errors. Therefore, a series of calibrations are required before application to improve measurement accuracy. The system errors of iToF cameras mainly come from lens error, wiggling error, and Fixed Phase Pattern Noise (FPPN). The main source of FPPN is that each pixel on the image sensor surface may be different during the manufacturing process, resulting in independent deviations for each pixel. At the same time, the demodulator drive signal is generally located at one end of the pixel array. When the demodulator drive signal drives the entire pixel array, the RC delay in the circuit causes a delay in the drive signal reaching pixels at different positions, which also results in different measured times of flight for pixels at different positions.

[0007] To ensure the measurement accuracy of iToF cameras, a series of calibrations are required, such as lens calibration, wiggling calibration, and FPPN calibration. Different calibrations require different testing environments and equipment. For example, lens calibration typically uses a checkerboard calibration board, while FPPN calibration requires a specially designed whiteboard to calibrate each pixel. This significantly increases production costs for mass production. Furthermore, since iToF camera calibration is generally performed linearly and step-by-step, with lens, wiggling, and FPPN calibrations performed sequentially after the module lens is installed, errors in the lens calibration results directly affect the FPPN calibration results. This means the final calibration result depends on the results of the previous calibrations. For instance, before FPPN calibration, the iToF camera must first undergo lens calibration, followed by wiggling calibration, and finally FPPN calibration using a whiteboard. Since FPPN calibration is the final step, its calibration process requires access to previous calibration results. However, iToF camera image sensors generally have low resolution, and lens calibration is prone to producing larger calibration errors than conventional high-resolution RGB cameras. Therefore, the errors introduced by the aforementioned lens calibration and wiggling calibration steps will accumulate in the final FPPN calibration result, affecting the accuracy of FPPN calibration. Furthermore, existing calibration methods struggle to calibrate multiple iToF image sensors simultaneously.

[0008] The FPPN calibration process typically involves illuminating a white board parallel to the iToF image sensor with a modulated light source, and then performing FPPN correction using the following formula:

[0009]

[0010] in, These are phase shift measurements. The value represents the true phase shift, and the wiggling value represents the wiggling calibration result for that pixel. Since the whiteboard's position is known and perpendicular to the optical axis of the iToF camera lens, the true phase shift value for each pixel can be calculated using a pinhole camera model, combined with the lens calibration result. However, the accuracy of the calculation result strongly depends on the accuracy of the lens calibration result, the whiteboard's mounting angle, and its absolute position. Furthermore, the whiteboard requires special manufacturing, resulting in high setup and maintenance costs.

[0011] Chinese patent application CN109903241A discloses a depth image calibration method and system for a TOF camera system. It uses a white target board for FPPN calibration and, considering the influence of noise, averages the results using a 5x5 window before fitting the FPPN error to a surface. However, switching to a white target board on the production line incurs certain costs, and the surface fitting method may introduce errors that do not meet the relevant accuracy requirements. Summary of the Invention

[0012] The purpose of this invention is to provide a fixed phase mode noise calibration device and method for iToF image sensors, which can make the FPPN calibration results no longer dependent on the lens calibration results, and eliminate the need to build and maintain a complex calibration board. It can also realize the simultaneous calibration of batch iToF image sensors, thereby reducing the FPPN calibration cost of iToF image sensors.

[0013] To achieve the above objectives, the present invention provides a fixed-phase mode noise calibration device for an iToF image sensor, comprising: at least one iToF image sensor, the iToF image sensor including a pixel array, wherein no lens is mounted on the iToF image sensor; an emitter for emitting a modulated light signal; and a first synchronization line electrically connecting the iToF image sensor and the emitter for synchronizing the emitter and the iToF image sensor in terms of modulation period and emission time; wherein the distance between the emitter and the iToF image sensor is such that the iToF image sensor is located within the illumination field of the modulated light signal, the iToF image sensor sends a start signal indicating the start of integration time to the emitter via the first synchronization line to periodically modulate the light intensity emitted by the emitter, and the iToF image sensor generates a demodulation signal with the same period as the start signal to integrate the received modulated light signal and convert it into an electrical signal.

[0014] In some embodiments, the device includes a plurality of iToF image sensors. The plurality of iToF image sensors are arranged in an array in a direction parallel to the plane where the emitter is located and are all located within the illumination field of the modulated light signal. One iToF image sensor serves as the master image sensor to generate the demodulated signal, and the other iToF image sensors serve as slave image sensors and are electrically connected to the master image sensor through a second synchronization line to synchronize the demodulated signal. This allows the plurality of iToF image sensors to be FPPN calibrated simultaneously and their respective FPPN calibration results to be obtained.

[0015] To achieve the above objectives, the present invention also provides a fixed phase mode noise calibration method for an iToF image sensor, comprising the following steps: performing wiggling calibration on the iToF image sensor before lens mounting to obtain the wiggling calibration result of the iToF image sensor; setting up an iToF image sensor fixed phase mode noise calibration device, the device comprising at least one iToF image sensor, an emitter, and a first synchronization line, wherein the iToF image sensor comprises a pixel array, no lens is mounted on the iToF image sensor, the emitter is used to emit a modulated light signal, and the first synchronization line electrically connects the iToF image sensor and the emitter to enable the emitter to synchronize with the iToF image sensor. The sensor is synchronized in modulation period and emission time, wherein the distance between the emitter and the iToF image sensor is such that the iToF image sensor is located within the illumination field of the modulated light signal; the iToF image sensor emits a start signal to indicate the start of integration time, which is synchronized to the emitter via the first synchronization line to periodically modulate the light intensity emitted by the emitter; and the iToF image sensor generates a demodulation signal with the same period as the start signal to integrate the received modulated light signal and convert it into an electrical signal to obtain the phase shift measurement value of each pixel; and the FPPN calibration result of each pixel is obtained based on the Wiggling calibration result and the phase shift measurement value.

[0016] This invention achieves FPPN calibration extremely easily by creating nearly identical light signal flight times for pixels at different positions within a pixel array, synchronizing the emitter and the iToF image sensor in terms of modulation period and emission time via a synchronization line, and ensuring the iToF image sensor falls within the illumination field of the modulated light signal. The equipment setup and maintenance costs are low. Calibration accuracy can be improved by increasing the distance between the emitter and the iToF image sensor to a certain extent. Since FPPN calibration is performed before the iToF image sensor lens is installed, the FPPN calibration result is independent of the lens calibration result, ensuring accurate and reliable results. Furthermore, it eliminates the need to calculate the actual distance or construct calibration whiteboards for precise angle and distance control, saving calibration costs. The synchronization line allows for batch FPPN calibration, further reducing equipment setup and maintenance costs. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram illustrating the working principle of an iToF camera.

[0019] Figure 2 This is a schematic diagram of continuous wave modulation ranging.

[0020] Figure 3 This is a schematic diagram of a fixed-phase mode noise calibration device for an iToF image sensor according to an embodiment of the present invention;

[0021] Figure 4 This is a schematic diagram of a fixed-phase mode noise calibration device for an iToF image sensor provided in another embodiment of the present invention;

[0022] Figure 5 A flowchart of the fixed phase mode noise calibration method for iToF image sensors provided by the present invention. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Please see Figure 3This is a schematic diagram of a fixed-phase mode noise calibration device for an iToF image sensor provided in an embodiment of the present invention. Figure 3 As shown, the iToF image sensor fixed-phase mode noise calibration device provided in this embodiment includes: an iToF image sensor 31, an emitter 32, and a first synchronization line 33. The iToF image sensor 31 includes a pixel array 311, wherein no lens is mounted on the iToF image sensor. The emitter 32 is controlled to emit continuously modulated light signals 329. The first synchronization line 33 electrically connects the iToF image sensor 31 and the emitter 32, and is used to synchronize the emitter 32 and the iToF image sensor 31 in terms of modulation period and emission time. The distance D1 between the emitter 32 and the iToF image sensor 31 ensures that the iToF image sensor 31 is located within the illumination field of view of the modulated light signal 329 (the area governed by lines 327 and 328). The iToF image sensor 31 sends a start signal indicating the start of the integration time to the emitter 32 via the first synchronization line 33 to periodically modulate the light intensity emitted by the emitter 32. The iToF image sensor 31 also generates a demodulation signal with the same period as the start signal to integrate the received modulated light signal and convert it into an electrical signal. Specifically, the pixel array 311 in the iToF image sensor 31 acts as a demodulator, used to sample, integrate, and convert the received modulated light signal into an electrical signal. After the integration time ends, the phase shift measurement value is obtained by performing iToF phase calculation on the data received by the iToF image sensor 31, thus obtaining the time-of-flight information of the light signal (modulated light signal 329 emitted by the emitter 32) arriving at each pixel in the pixel array.

[0025] In other words, in actual use, it is only necessary to meet the requirement that the modulated light signal 329 emitted by the emitter 32 can illuminate the entire iToF image sensor 31, and to electrically connect the synchronization line between the emitter 32 and the iToF image sensor 31, so that calibration work can be carried out. The equipment setup and maintenance costs are low.

[0026] In some embodiments, the distance between the emitter 32 and the iToF image sensor 31 is greater than 10 cm. Since the actual size of the pixel array in the iToF image sensor is very small—typically only a few square millimeters—the distance between the emitter 32 and the iToF image sensor 31 only needs to be greater than 10 cm. This means the difference in flight distance between the light signal (the modulated light signal 329 emitted by the emitter 32) and pixels at different locations within the pixel array area of ​​the iToF image sensor 31 will be less than 0.1 mm. In this case, it can be assumed that the modulated light signal 329 emitted from the emitter 32 travels the same amount of time to reach the pixels at different locations in the pixel array.

[0027] Based on the characteristics of FPPN calibration, FPPN calibration can be easily achieved by creating nearly identical light signal flight times for pixels at different positions within the pixel array, synchronizing the emitter 32 and the iToF image sensor 31 in terms of modulation period and emission time via a synchronization line, and ensuring that the iToF image sensor 31 falls within the illumination field of the modulated light signal. This results in low equipment setup and maintenance costs. Calibration accuracy can be improved by increasing the distance between the emitter 32 and the iToF image sensor 31 to a certain extent. Since FPPN calibration is performed before the iToF image sensor lens is installed, the FPPN calibration result is independent of the lens calibration result, ensuring accuracy and reliability. Furthermore, it eliminates the need to calculate the actual distance or construct calibration whiteboards for precise angle and distance control, thus saving calibration costs.

[0028] In some embodiments, the emitter 32 typically uses an active light source in the near-infrared wavelength band to emit a continuously modulated optical signal 329. For example, it may employ a vertical cavity surface-emitting laser (VCSEL), an infrared emitter (IR emitter), or a light-emitting diode (LED).

[0029] In some embodiments, the device further includes a bandpass filter 34, which is mounted on the surface of the iToF image sensor 31 near the emitter 32. The bandpass filter 34 filters out the influence of ambient light on the calibration results, thus enabling calibration without an optical darkroom. By mounting a bandpass filter 34 on the surface of the iToF image sensor 31, other wavelengths of ambient light are filtered out, allowing only the light signal emitted by the emitter 32 to pass through the bandpass filter 34 and be received by the iToF image sensor 31, completing the FPPN calibration. This allows FPPN calibration to be performed even without an optical darkroom.

[0030] The working principle of the fixed phase mode noise calibration device for iToF image sensor provided in this embodiment is as follows: (1) Before the lens of the iToF image sensor is installed, Wiggling calibration is performed to obtain the Wiggling calibration result of the iToF image sensor. After that, the device is set up as follows: Figure 3 The iToF image sensor fixed phase mode noise calibration device shown; (2) the iToF image sensor sends a start signal to start the integration time and synchronizes it to the light emitter through the first synchronization line to periodically modulate the light intensity emitted by the light emitter; (3) at the same time, the iToF image sensor generates a demodulation signal with the same period as the start signal to integrate the received modulated light signal and convert it into an electrical signal to obtain the phase shift measurement value of each pixel; (4) according to the wiggling calibration result and the phase shift measurement value, the FPPN calibration result of each pixel is obtained.

[0031] Specifically, the FPPN calibration result can be obtained using the following formula:

[0032]

[0033] in, The phase shift measurement value is... The phase shift is the true value, and wiggling is the wiggling calibration result. Because the device described in this embodiment is configured such that the modulated light signal 329 emitted from the emitter 32 travels the same flight time to reach pixels at different positions in the pixel array, the true phase shift values ​​of different pixels are... The same applies; it can be set to 0. Because... The fixed deviation caused by setting it to 0 can be obtained in advance during the Wiggling calibration. Therefore, the difference in phase shift measurements at different pixel locations, after eliminating the wobble error, comes entirely from the fixed phase mode noise itself. At this point, the fppn only retains the difference between each pixel.

[0034] In some embodiments, in order to improve test accuracy and reduce time noise, multiple depth information images can be captured to obtain an average depth information image, and then each pixel in the average depth information image can be calibrated using Wiggling to obtain the final accurate FPPN calibration result.

[0035] Please see Figure 4 This is a schematic diagram of a fixed-phase mode noise calibration device for an iToF image sensor provided in another embodiment of the present invention. Figure 4As shown, in this embodiment, the device includes multiple iToF image sensors 31. These multiple iToF image sensors 31 are arranged in an array parallel to the plane of the emitter 32, all located within the illumination field of the modulated light signal 329. One iToF image sensor 31 acts as the master image sensor to generate the demodulated signal, while the other iToF image sensors act as slave image sensors and are electrically connected to the master image sensor via a second synchronization line 41 to synchronize the demodulated signal. This allows for simultaneous FPPN calibration of multiple iToF image sensors 31 and the acquisition of their respective FPPN calibration results. By adding a synchronization line 41 to synchronize the demodulated signals of all iToF image sensors 31, as long as all iToF image sensors 31 remain within the illumination field of the modulated light signal, the time-of-flight of the light signal sensed by different pixels within the pixel array of the same iToF image sensor is consistent. Therefore, a batch of iToF image sensors can be FPPN calibrated simultaneously without interference.

[0036] In some embodiments, the time delay between the first synchronization line 33 and the second synchronization line 41 is less than or equal to 10 µs. If there is a time delay between the first synchronization line 33 for synchronously controlling the emitter 32 and the iToF image sensor 31, and the second synchronization line 41 for synchronously controlling each iToF image sensor 31, as long as the control time delay is small (less than or equal to 10 µs), it will not affect the calibration results. Each iToF image sensor 31 can obtain its own FPPN calibration result by using the same method as the previous single iToF image sensor FPPN calibration.

[0037] Based on the same inventive concept, this invention also provides a method for calibrating fixed-phase mode noise in an iToF image sensor. The provided method for calibrating fixed-phase mode noise in an iToF image sensor can employ methods such as... Figures 3-4 The iToF image sensor fixed phase mode noise calibration device shown completes the fixed phase mode noise calibration of the iToF image sensor.

[0038] Please see Figure 5 This is a flowchart of the iToF image sensor fixed-phase mode noise calibration method provided by the present invention. Figure 5As shown, the fixed phase mode noise calibration method for an iToF image sensor described in this embodiment includes the following steps: S1, performing wiggling calibration on the iToF image sensor before lens installation to obtain the wiggling calibration result of the iToF image sensor; S2, setting up an iToF image sensor fixed phase mode noise calibration device, the device including at least one iToF image sensor, an emitter, and a first synchronization line, the iToF image sensor including a pixel array, the iToF image sensor without a lens installed, the emitter being used to emit a modulated light signal, and the first synchronization line electrically connecting the iToF image sensor and the emitter to enable the emitter and the iToF image sensor to be in sync. The modulation period and emission time are synchronized, wherein the distance between the emitter and the iToF image sensor is such that the iToF image sensor is located within the illumination field of the modulated light signal; S3, the iToF image sensor emits a start signal to begin the integration time, and synchronizes it to the emitter through the first synchronization line, so as to periodically modulate the light intensity emitted by the emitter, and generate a demodulation signal with the same period as the start signal through the iToF image sensor, so as to integrate the received modulated light signal and convert it into an electrical signal to obtain the phase shift measurement value of each pixel; and S4, the FPPN calibration result of each pixel is obtained according to the wiggling calibration result and the phase shift measurement value.

[0039] Specifically, the FPPN calibration result is obtained using the following formula:

[0040]

[0041] in, The phase shift measurement value is... The true phase shift value is 0, and Wiggling is the Wiggling calibration result, which is obtained in advance during the Wiggling calibration because... The fixed deviation resulting from a value of 0.

[0042] In some embodiments, in order to improve testing accuracy and reduce temporal noise, step S1 is further included as follows: after capturing multiple depth information images to obtain an average depth information image, each pixel in the average depth information image is calibrated using Wiggling to reduce temporal noise.

[0043] In some embodiments, the device includes a plurality of iToF image sensors. The plurality of iToF image sensors are arranged in an array in a direction parallel to the plane of the emitter and are all located within the illumination field of the modulated light signal. One iToF image sensor serves as the master image sensor to generate the demodulated signal, and the other iToF image sensors serve as slave image sensors and are electrically connected to the master image sensor via a second synchronization line to synchronize the demodulated signal. Step S1 further includes: performing Wiggling calibration on each iToF image sensor before mounting the lens to obtain the Wiggling calibration result for each iToF image sensor. Step S3 further includes: The main image sensor emits a start signal indicating the start of the integration time, and synchronizes it to the emitter via the first synchronization line to periodically modulate the light intensity emitted by the emitter. The main image sensor also generates a demodulated signal with the same period as the start signal, and synchronizes it to all the slave image sensors via the second synchronization line. This allows each iToF image sensor to integrate the received modulated light signal and convert it into an electrical signal, thereby obtaining the phase shift measurement value of each pixel of each iToF image sensor. Step S4 further includes: obtaining the FPPN calibration result of each pixel of each iToF image sensor based on the wiggling calibration result and the phase shift measurement value of each iToF image sensor.

[0044] The working principle of the iToF image sensor fixed phase mode noise calibration device can be referred to Figures 3-4 The corresponding description of the iToF image sensor fixed phase mode noise calibration device shown is not repeated here.

[0045] As can be seen from the above, this invention, starting from the characteristics of FPPN calibration, achieves FPPN calibration extremely easily by creating nearly identical light signal flight times for pixels at different positions within the pixel array, synchronizing the emitter 32 and the iToF image sensor 31 in terms of modulation period and emission time via a synchronization line, and simply requiring the iToF image sensor 31 to fall within the illumination field of the modulated light signal. This results in low equipment setup and maintenance costs. Calibration accuracy can be improved by increasing the distance between the emitter 32 and the iToF image sensor 31 to a certain extent. Since FPPN calibration is performed before the iToF image sensor lens is installed, the FPPN calibration result is independent of the quality of the lens calibration result, ensuring accurate and reliable results. Furthermore, it eliminates the need to calculate the actual distance or construct calibration whiteboards and other mechanisms for precise angle and distance control, thus saving calibration costs.

[0046] Based on the same inventive concept, the present invention also provides an electronic device, including a memory, a processor, and a computer-executable program stored in the memory and executable on the processor; when the processor executes the computer-executable program, it implements as follows: Figure 5 The steps of the iToF image sensor fixed phase mode noise calibration method are shown.

[0047] Within the scope of this inventive concept, embodiments can be described and illustrated based on modules that perform one or more of the described functions. These modules can be physically implemented by analog and / or digital circuitry, such as logic gates, integrated circuits, microprocessors, microcontrollers, memory circuits, passive electronic components, active electronic components, optical components, hardwired circuits, etc., and can optionally be driven by firmware and / or software. The circuitry can be implemented, for example, in one or more semiconductor chips. The circuitry constituting a module can be implemented by dedicated hardware, or by a processor (e.g., one or more programmed microprocessors and associated circuitry), or by a combination of dedicated hardware performing some functions of the module and a processor performing other functions of the module. Without departing from the scope of this inventive concept, each module of an embodiment can be physically divided into two or more interactive and discrete modules. Similarly, without departing from the scope of this inventive concept, the modules of an embodiment can be physically combined into more complex modules.

[0048] Generally, terms can be understood at least partially from their usage in context. For example, the term "one or more" as used herein depends at least in part on the context and can be used to describe a feature, structure, or characteristic in a singular sense, or in a plural sense to describe a combination of features, structures, or characteristics. Additionally, the term "based on" can be understood not necessarily to express an exclusive set of factors, but rather, alternatively, also depends at least in part on the context, allowing for the presence of other factors that are not necessarily explicitly described.

[0049] It should be noted that the terms "comprising" and "having," and their variations, used in this invention document are intended to cover non-exclusive inclusion. The terms "first," "second," etc., are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence, unless explicitly indicated by the context. It should be understood that such data used interchangeably where appropriate. Furthermore, embodiments and features within embodiments of this invention can be combined with each other unless otherwise specified. In addition, descriptions of well-known components and technologies have been omitted in the above description to avoid unnecessarily obscuring the concepts of this invention. In the various embodiments described above, each embodiment focuses on its differences from other embodiments; similar or identical parts between embodiments can be referred to interchangeably.

[0050] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An iToF image sensor fixed pattern noise calibration apparatus, characterized by, include: Multiple iToF image sensors, each iToF image sensor including a pixel array, wherein no lens is mounted on the iToF image sensor; A light emitter, used to emit modulated light signals; The first synchronization line is electrically connected to the iToF image sensor and the emitter, and is used to synchronize the emitter and the iToF image sensor in terms of modulation period and emission time; The distance between the emitter and the iToF image sensor is such that the iToF image sensor is located within the illumination field of the modulated light signal. The iToF image sensor sends a start signal to the emitter via the first synchronization line to initiate the integration time, thereby periodically modulating the light intensity emitted by the emitter. The iToF image sensor generates a demodulation signal with the same period as the start signal to integrate the received modulated light signal and convert it into an electrical signal. In a direction parallel to the plane where the light emitter is located, multiple iToF image sensor arrays are arranged and all located within the illumination field of the modulated light signal. One iToF image sensor serves as the master image sensor to generate the demodulated signal, while the other iToF image sensors serve as slave image sensors and are electrically connected to the master image sensor via a second synchronization line to synchronize the demodulated signal. This allows for simultaneous FPPN calibration of multiple iToF image sensors and the acquisition of their respective FPPN calibration results. The acquisition of their respective FPPN calibration results includes obtaining the FPPN calibration results of each pixel of each iToF image sensor based on the wiggling calibration results and phase shift measurements of each iToF image sensor.

2. The apparatus of claim 1, wherein, The distance between the emitter and the iToF image sensor is greater than 10 centimeters.

3. The apparatus according to claim 1, characterized in that, The light emitter is any one of a vertical cavity surface-emitting laser, an infrared light emitter, or a light-emitting diode.

4. The apparatus according to claim 1, characterized in that, The device also includes a bandpass filter, which is mounted on the surface of the iToF image sensor near the emitter to filter out the influence of ambient light on the calibration results.

5. The apparatus according to claim 1, characterized in that, The time delay between the first synchronization line and the second synchronization line is less than or equal to 10 microseconds.

6. A method for calibrating fixed-phase mode noise in an iToF image sensor, characterized in that, Includes the following steps: Before the lens of the iToF image sensor is installed, each iToF image sensor is calibrated by Wiggling to obtain the Wiggling calibration result of each iToF image sensor; An iToF image sensor fixed-phase mode noise calibration device is provided. The device includes multiple iToF image sensors, an emitter, and a first synchronization line. The iToF image sensor includes a pixel array and has no lens. The emitter emits a modulated light signal. The first synchronization line electrically connects the iToF image sensor and the emitter to synchronize the emitter and the iToF image sensor in terms of modulation period and emission time. The distance between the emitter and the iToF image sensor is such that the iToF image sensor is located within the illumination field of the modulated light signal. In a direction parallel to the plane of the emitter, multiple iToF image sensor arrays are arranged and all located within the illumination field of the modulated light signal. One iToF image sensor acts as the master image sensor to generate a demodulated signal, and the other iToF image sensors act as slave image sensors and are electrically connected to the master image sensor via a second synchronization line to synchronize the demodulated signal. The main image sensor emits a start signal indicating the start of the integration time, which is synchronized to the emitter via the first synchronization line to periodically modulate the light intensity emitted by the emitter. The main image sensor also generates a demodulated signal with the same period as the start signal, which is synchronized to all the slave image sensors via the second synchronization line. This allows each iToF image sensor to integrate the received modulated light signal and convert it into an electrical signal, thereby acquiring the phase shift measurement value of each pixel of each iToF image sensor. Based on the Wiggling calibration results and phase shift measurements of each iToF image sensor, the FPPN calibration results of each pixel of each iToF image sensor are obtained.

7. The method according to claim 6, characterized in that, The FPPN calibration result is obtained using the following formula: ； in, The phase shift measurement value is... The actual value of the phase shift is 0. The result of the Wiggling calibration is given in advance, and is obtained beforehand in the Wiggling calibration due to... The fixed deviation resulting from a value of 0.

8. The method according to claim 6, characterized in that, Before the step of performing wiggling calibration to obtain the wiggling calibration result of the iToF image sensor before lens installation, the method further includes: after capturing multiple depth information images to obtain an average depth information image, performing wiggling calibration on each pixel in the average depth information image to reduce temporal noise.

Images