Anti-non-system laser source noise method for DTOF image sensor

Abstract

The application discloses an anti-non-system laser source noise method for a DTOF image sensor, and the method comprises the following steps: a laser source of a system emits light pulse signals according to N working periods; a certain number of delay intervals are inserted between two adjacent working periods, and the number of the delay intervals inserted between each two adjacent working periods is different; and the light pulse signals of the N working periods after the delay intervals are inserted are accumulated on a histogram to form corresponding peak values. The system has the suppression ability for non-system laser source noise, and the accumulation of the system laser source signals does not have an influence, especially in the case that the traditional suppression method is invalid for a binary method and a quarter method system, and the method still has a good suppression effect, fully avoids the invalidity of the binary method and the quarter method system, and improves the signal-to-noise ratio, the detection distance and the precision of the system.

Description

Technical Field

[0001] This invention relates to the field of TOF image sensor and circuit technology, and specifically to a method for resisting non-system laser source noise in DTOF image sensors. Background Technology

[0002] Image sensors have always been a hot topic of human interest and research. However, with the development of modern science and technology, two-dimensional images can no longer meet human needs. More and more application scenarios require accurate perception of distance information, so three-dimensional imaging technology has emerged.

[0003] DTOF image sensors are a new type of 3D image sensor capable of long-distance, high-precision, multi-point distance imaging, thereby enabling 3D surface reconstruction of objects. A DTOF image sensor system consists of a laser emitter, optical elements, a SPAD macropixel array, pixel front-end circuitry, a Time-to-Digital Converter (TDC), timing control circuitry, and some peripheral circuits. DTOF image sensors calculate the distance between the target and the sensor by measuring the time difference between the emitted and received light pulses. Their performance is limited by various noise sources, including dark noise from SPAD pixels, afterpulse noise, ambient light noise, and multi-peak noise from multiple laser sources. Among these, the most critical noise is the multi-peak noise caused by multiple non-system laser sources. This noise has the same response form as the system's own laser source, accumulating into a series of signal peaks, differing only in their position on the time axis. This makes it impossible for the TDC circuit to distinguish which signal peak corresponds to the system's own laser source, ultimately leading to the complete failure of the DTOF system.

[0004] To distinguish the signal peaks corresponding to different laser sources, different laser sources can be "encoded," generating peaks with "coded" information. This allows for the differentiation and selection of different peaks, ultimately obtaining the peak corresponding to the light source in this system and calculating the true distance. A relatively simple encoding method is as follows: Figure 1 As shown: The laser source of this system emits a pulse, and then emits a second pulse at a fixed time interval tn. As a result, the laser source of this system will produce two peaks, and the time distance between the two peaks is the emission interval tn of the two pulses. Similarly, other laser sources will also produce two peaks, with a time interval of tm. However, the distance between the two peaks produced by different laser sources is different. After accumulation, the distance t between different peaks can be identified until the two peaks corresponding to the two pulses of this laser source are found.

[0005] The above method is effective for histogram-accumulating DTOF systems. However, it becomes ineffective for DTOF systems using bisection or quartic time quantization methods. This is because bisection and quartic methods only count pulse data; the data does not accumulate, resulting in the absence of peak values ​​in the results and rendering the original encoding method ineffective. The bisection quantization process is as follows: Figure 2 As shown, in each quantization, the sign bit 0 or 1 of the current quantization is obtained by comparing the number of pulses in the two intervals. This process is repeated until all the sign bits are obtained as the quantization code value.

[0006] The foundation of traditional methods lies in the "encoding" of the laser source signal and the accumulation of multiple trigger signal pulses of the laser source signal to make the "encoding" characteristics manifest. However, the binary and quartic methods do not support data accumulation. Therefore, the original method of suppressing noise from sources other than the system based on the "encoding" of the laser source signal fails.

[0007] In related technologies, Chinese invention patent application CN110632578A discloses a system and method for time-coded time-of-flight distance measurement. The system includes: a transmitter configured to emit a pulse train of optical signals with dual random time coding, the pulse train including N groups of pulses emitted in a second random time coding form, each pulse group containing n pulses emitted in a first random time coding form; a collector configured to collect photons in the pulse train of optical signals reflected back by an object; and a processing circuit connected to the transmitter and the collector, configured to count the photons to form a time series of N pulse group periodic single-photon counts; and to plot a histogram based on the first random time coding and the N pulse group periodic single-photon count time series.

[0008] In this scheme, the encoding method only exists at the transmitting end. The encoding method is based on the gradual increase of random time length and transmission pulse interval, and requires a large number of additional processing circuits to realize the superposition of its signals. Summary of the Invention

[0009] The technical problem to be solved by this invention is how to effectively suppress noise from laser sources other than those in this system.

[0010] The present invention solves the above-mentioned technical problems through the following technical means:

[0011] A method for resisting non-intra-system laser source noise in DTOF image sensors is proposed, the method comprising:

[0012] The laser source of this system emits optical pulse signals in N working cycles;

[0013] A certain number of delay intervals are inserted between two adjacent work cycles, and the number of delay intervals inserted between each pair of adjacent work cycles is different;

[0014] The optical pulse signals of N working cycles after the insertion of the delay interval are accumulated on the histogram to form the corresponding peak values.

[0015] Furthermore, the total number of delay intervals inserted over N working weeks and the length of each delay interval remain unchanged.

[0016] Furthermore, inserting a certain number of delay intervals between two adjacent work cycles includes:

[0017] n delay intervals are inserted between the nth working cycle and the (n+1)th working cycle, where 1≤n≤N-1.

[0018] Furthermore, inserting a certain number of delay intervals between two adjacent work cycles includes:

[0019] m1 delay intervals are inserted between the nth working cycle and the (n+1)th working cycle, and m2 delay intervals are inserted between the (n+1)th working cycle and the (n+2)th working cycle, where m1+m2=N.

[0020] Furthermore, inserting a certain number of delay intervals between two adjacent work cycles includes:

[0021] The number of insertions is m in the nth interval and the Nnth interval, respectively. n and m N-n The delay interval, and m n +m N-n =N.

[0022] Furthermore, for systems of the same type, when the encoding method is "insert n delay intervals between the nth working cycle and the (n+1)th working cycle, where 1≤n≤N-1", the sum of the delays of each level that are more than the previous level is taken as the total misalignment delay, where the total misalignment delay ta=(N-1)*t, t represents the delay interval, the total misalignment delay ta≥MT, M≥2, and T represents the working cycle.

[0023] Furthermore, this invention also proposes a system for resisting non-intrinsic laser source noise for DTOF image sensors, the system comprising:

[0024] The optical pulse signal generation module is used by the laser source of this system to emit optical pulse signals according to N working cycles.

[0025] The delay interval module is used to insert a certain number of delay intervals between two adjacent work cycles, and the number of delay intervals inserted between each pair of adjacent work cycles is different;

[0026] The receiving quantization module is used to accumulate the optical pulse signals of N working cycles after the insertion of the delay interval on the histogram to form the corresponding peak value.

[0027] Furthermore, the total number of delay intervals inserted during the N working weeks and the length of each delay interval remain unchanged.

[0028] Furthermore, the delay interval module is specifically used for a certain type of system:

[0029] n delay intervals are inserted between the nth working cycle and the (n+1)th working cycle, where 1≤n≤N-1;

[0030] Alternatively, m1 delay intervals can be inserted between the nth working cycle and the (n+1)th working cycle, and m2 delay intervals can be inserted between the (n+1)th working cycle and the (n+2)th working cycle, where m1+m2=N;

[0031] Alternatively, insert a number of m at the nth interval and the Nnth interval respectively. n and m N-n The delay interval, and m n +m N-n =N.

[0032] Furthermore, the encoding method used in the delay interval module is to insert n delay intervals between the nth working cycle and the (n+1)th working cycle, where 1≤n≤N-1, the sum of the delays of each level that are more than the previous level is taken as the total misalignment delay, ta=(N-1)*t, t represents the delay interval, the total misalignment delay ta≥MT, M≥2, and T represents the working cycle.

[0033] The advantages of this invention are:

[0034] (1) The present invention inserts a certain number of delay intervals between each two adjacent working cycles, and the number of delay intervals inserted between each adjacent working cycle is different, so that the left edge of each working cycle is the start time of the entire DTOF system. In this way, the laser emission and reception quantization system of the present system always have the same delay in each working cycle, that is, their start time is the same. Therefore, the relative position of the accumulated signal of the laser source of the present system on the histogram does not change, which can enable the present system to have the ability to suppress noise of non-the present system laser sources, without affecting the accumulation of the laser source signal of the present system. Especially when the traditional suppression method fails when using the bisection method or the quartile method system, the new method still has a good suppression effect, which fully avoids the failure of the bisection method and the quartile method system, and also improves the signal-to-noise ratio of the system, improves the anti-interference ability of the present system, and improves the detection distance and accuracy of the system.

[0035] (2) By using different delay interval insertion methods, this invention “encodes” the start time of each cycle of the system, thus solving the problem of mutual interference between different DTOF systems in the same environment.

[0036] (3) The present invention sets the total misalignment delay to twice or even more times the working period T. The more times the misalignment delay is set, the stronger the suppression capability of non-system laser source noise is, thus making the suppression effect of time “encoding” more significant.

[0037] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of dual-pulse suppression of non-system laser source noise mentioned in the background section of this invention;

[0039] Figure 2 This is a schematic diagram of the binary quantization method mentioned in the background section of this invention;

[0040] Figure 3 This is a flowchart illustrating a method for resisting non-system laser source noise in a DTOF image sensor, as proposed in an embodiment of the present invention.

[0041] Figure 4 This is a schematic diagram of a time-coded method for suppressing uncorrelated laser source noise according to an embodiment of the present invention;

[0042] Figure 5 This is a schematic diagram of a time-coded method for suppressing uncorrelated laser source noise according to an embodiment of the present invention;

[0043] Figure 6This is a schematic diagram of a system for resisting non-system laser source noise for a DTOF image sensor, proposed in another embodiment of the present invention. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. 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.

[0045] like Figure 3 As shown, the first embodiment of the present invention proposes a method for resisting non-system laser source noise for DTOF image sensors, the method comprising the following steps:

[0046] S10. The laser source of this system emits optical pulse signals in N working cycles;

[0047] S20. Insert a certain number of delay intervals between two adjacent work cycles, and the number of delay intervals inserted between each pair of adjacent work cycles is different;

[0048] S30. Accumulate the optical pulse signals of N working cycles after inserting the delay interval on the histogram to form the corresponding peak value.

[0049] It should be noted that the time encoding method in this embodiment is based on the consistency of operation between the transmitting and receiving systems, and this encoding method exists at both the transmitting and receiving ends. Different types of systems have different duty cycle lengths, while systems of the same type refer to systems with the same duty cycle length and the same number of frame cycles N. Encoding is achieved by inserting different numbers of delay intervals between different duty cycles. The number of delay intervals is unique and fixed within the same type of system. Time encoding is achieved by arranging different numbers of delay intervals between different duty cycles. Therefore, the delay intervals inserted in this embodiment are not incremental but out of order.

[0050] By assigning a unique "encoding" to the optical signal of this system in time, unlike the traditional time-independent "encoding" method, this scheme inserts a certain number of delay intervals between every two adjacent working cycles, and the number of delay intervals inserted between each adjacent working cycle is different. This makes the left edge of each working cycle the start time of the entire DTOF system (i.e., the laser emission time point, the TDC start time point). In this way, the laser emission and receiving quantization system of this system always have the same delay in each working cycle, that is, their start time is the same. Therefore, the relative position of the signal corresponding to the laser source of this system does not change on the histogram, and a corresponding peak is formed. However, for light sources other than this system, the time of their laser source emission pulse cannot have the same delay as the start time of this receiver. This causes the position of the laser source other than this system on the histogram to change in each cycle. Finally, after N working cycles, the signal of the laser source other than this system cannot form an effective accumulation on the histogram. By "encoding" the start time of each cycle of this system, the trigger signal pulses of non-system laser sources are distributed across the entire time axis. This non-system laser source noise loses its original time correlation for this system and thus does not affect the true signal peak. This can greatly improve the signal-to-noise ratio of this system and enhance its anti-interference capability.

[0051] The novel encoding method proposed in this embodiment obtains pulses that can be directly quantized using traditional TDC histogram accumulation, binary division, or quartic division methods without any processing circuitry. These methods effectively suppress noise from non-system laser sources, improving the system's signal-to-noise ratio and consequently enhancing measurement distance and accuracy. Furthermore, by uniformly distributing non-system laser signals along the histogram time axis, only the system's own laser signal is effectively accumulated, resulting in superior suppression performance.

[0052] In one embodiment, the total number of delay intervals inserted over N working weeks and the length of each delay interval remain unchanged.

[0053] It should be noted that in practical applications, if a system with the same "encoding" is encountered, this method of resisting noise from non-system laser sources will fail. For example, traditional methods will also fail if they encounter the same "encoding" as traditional methods. Therefore, multiple "encoding" methods are necessary, and different time "encoding" methods can be used for different systems: the number of delay intervals and the delay length of each delay do not change in various encoding methods; only the order of the different delay lengths changes. The specific encoding method can be determined by those skilled in the art based on the actual situation.

[0054] By adopting different "encoding" methods for different types of systems, each "encoding" system can suppress noise from laser sources that do not belong to it, effectively solving the problem of mutual interference between different DTOF systems in the same environment. This is of great significance for the application of DTOF systems in autonomous driving.

[0055] It should be noted that the delay interval can be regarded as a relatively fixed time period. For different DTOF systems, this delay interval (time period) may be different, but for the same DTOF system, this delay interval is fixed.

[0056] In one embodiment, the delay interval is generally T×M÷N, where T is the period corresponding to the maximum detection distance, M≥2 is M times the working period T, and N is the number of working periods experienced by each frame of a traditional DTOF system.

[0057] The method of setting the delay interval value in this embodiment is related to the proposed method of resisting non-local system light sources. By adding different numbers of delay intervals between two working cycles, the noise of non-local system laser sources is evenly distributed on the time axis of the histogram, so that the noise of non-local system laser sources cannot accumulate on the histogram like that of local system laser sources.

[0058] In one embodiment, step S20: inserting a certain number of delay intervals between two adjacent work cycles includes:

[0059] n delay intervals are inserted between the nth working cycle and the (n+1)th working cycle, where 1≤n≤N-1.

[0060] In one embodiment, step S20: inserting a certain number of delay intervals between two adjacent work cycles includes:

[0061] m1 delay intervals are inserted between the nth working cycle and the (n+1)th working cycle, and m2 delay intervals are inserted between the (n+1)th working cycle and the (n+2)th working cycle, where m1+m2=N.

[0062] In one embodiment, step S20: inserting a certain number of delay intervals between two adjacent work cycles includes:

[0063] The number of insertions is m in the nth interval and the Nnth interval, respectively. n and m N-n The delay interval, and m n +m N-n =N.

[0064] Specifically, this delay interval insertion method maintains a constant total number of delay intervals, with each type of delay interval appearing only once. The set of different delay interval counts across N-1 periodic intervals constitutes the encoded set. For example, inserting m1 and m delay intervals in the 1st and N-1th intervals respectively. N-1 The delay interval, m1+m N-1 = N, with the number of insertions in the 2nd interval and the (N-2)th interval being m2 and m respectively. N-2 The delay interval, m2+m N-2 =N, and the number of iterations will be calculated by analogy thereafter.

[0065] It should be noted that the first interval refers to the interval between the first and second work cycles, and the (N-1)th interval refers to the interval between the (N-1)th and Nth work cycles.

[0066] It should be noted that the above are several ways to add different numbers of delay intervals for different time positions in this embodiment. The purpose is to distribute the noise from non-system laser sources evenly on the time axis of the histogram by using different numbers of delay intervals between two working cycles, so that the noise from non-system laser sources cannot accumulate on the histogram like the laser source of this system. Those skilled in the art can also use other encoding methods according to the actual situation. This embodiment does not make specific limitations.

[0067] The existence of multiple encoding methods is to address mutual interference between systems with the same anti-non-local laser source mechanism when used in the same environment. If the encoding methods are the same, multiple laser sources may interfere with each other. If the encoding methods are different, different encoding systems with the same mechanism will suppress non-local laser source signals from each other. This makes it possible to use systems with the same mechanism but different encoding methods in the same environment.

[0068] In one embodiment, for systems of the same type, when the encoding method is "insert n delay intervals between the nth working cycle and the (n+1)th working cycle, where 1≤n≤N-1", the sum of the delays of each level that are more than the previous level is taken as the total misalignment delay, the total misalignment delay ta=(N-1)*t, t represents the delay interval, the total misalignment delay ta≥MT, M≥2, and T represents the working cycle.

[0069] It should be noted that different types of systems have different periods T and different numbers of working cycles N. Under the condition that the total misalignment delay is defined as unchanged, this type of system must meet the rules that the total misalignment delay ta≥MT and M≥2 in order to realize the function of this mechanism.

[0070] It should be noted that in order to make the suppression effect of time "encoding" more significant, the total misalignment delay (the delay of each level is more than the previous level) ta = (N-1)*t should be M times the period T, where M ≥ 2. The higher the multiple, the stronger the suppression capability for laser source noise that is not in this system.

[0071] The novel encoding method proposed in this embodiment does not focus on accumulation, but rather on preserving the signal peak value of the laser source itself during data quantization while eliminating the peak values ​​of noise from laser sources outside the system. The most significant laser source noise affecting this system is in-frequency noise, which accumulates at the same time point in each working cycle, resulting in the most significant accumulation effect. Assuming that 200 cycles are used in a single quantization operation in the DTOF system, denoted as T1, T2, up to T200, the encoding method used is as follows:

[0072] (1) As Figure 4 As shown, t is inserted between T1 and T2, 2t is inserted between T2 and T3, 3t is inserted between T3 and T4, and so on, until finally 199t is inserted between T199 and T200. The left edge of each period T is the time when the entire DTOF system starts working (that is, the laser emission time point, the time when TDC starts working). In this way, the laser emission and reception quantization system of this system always have the same delay in each period, that is, their start time is the same. Therefore, the relative position of the signal corresponding to the laser source of this system accumulated on the histogram does not change, and thus a corresponding peak value is formed.

[0073] (2) The delay intervals can be arranged in the manner of t, 199t, 2t, 198t (e.g. Figure 5 The code shown in Figure 1) can also be arranged in the manner of t, 100t, 2t, 101t (e.g. Figure 5 The codes shown are 1 and 2, or arranged in other ways, so that different systems have different codes. Different code systems themselves have the effect of suppressing laser source noise that does not belong to them.

[0074] like Figure 6 As shown, the second embodiment of the present invention also proposes a system for resisting non-local laser source noise for a DTOF image sensor, the system comprising:

[0075] The optical pulse signal generation module 10 is used by the laser source of this system to emit optical pulse signals according to N working cycles.

[0076] The delay interval module 20 is used to insert a certain number of delay intervals between two adjacent working cycles, and the number of delay intervals inserted between each pair of adjacent working cycles is different.

[0077] The receiving quantization module 30 is used to accumulate the optical pulse signal of N working cycles after the insertion of the delay interval on the histogram to form the corresponding peak value.

[0078] This embodiment inserts a certain number of delay intervals between each two adjacent working cycles, and the number of delay intervals inserted between each adjacent working cycle is different. This ensures that the left edge of each working cycle represents the start time of the entire DTOF system. In this way, the laser emission and reception quantization systems of this system always have the same delay within each working cycle, meaning their start times are the same. Therefore, the relative position of the accumulated signal corresponding to the laser source of this system on the histogram does not change. This allows the system to suppress noise from non-system laser sources without affecting the accumulation of the laser source signal of this system. Especially when traditional suppression methods fail using the bisection or quartic method, the new method still has a good suppression effect, effectively avoiding the failure of the bisection and quartic method systems. It also improves the signal-to-noise ratio of the system, enhances the anti-interference capability of the system, and improves the detection range and accuracy of the system.

[0079] In one embodiment, the total number of delay intervals inserted over N working weeks and the length of each delay interval remain unchanged.

[0080] In one embodiment, the delay interval module is specifically used for a certain type of system:

[0081] n delay intervals are inserted between the nth working cycle and the (n+1)th working cycle, where 1≤n≤N-1;

[0082] Alternatively, m1 delay intervals can be inserted between the nth working cycle and the (n+1)th working cycle, and m2 delay intervals can be inserted between the (n+1)th working cycle and the (n+2)th working cycle, where m1+m2=N;

[0083] Alternatively, insert a number of m at the nth interval and the Nnth interval respectively. n and m N-n The delay interval, and m n +m N-n =N.

[0084] This embodiment solves the problem of mutual interference between different DTOF systems in the same environment by using different delay interval insertion methods to "encode" the start time of each cycle of this system.

[0085] In one embodiment, the encoding method used in the delay interval module 20 is to insert n delay intervals between the nth working cycle and the (n+1)th working cycle, wherein when 1≤n≤N-1, the sum of the delays of each level that are more than the previous level is taken as the total misalignment delay, ta=(N-1)*t, t represents the delay interval, the total misalignment delay ta≥MT, M≥2, and T represents the working cycle.

[0086] In this embodiment, the total misalignment delay is set to M times the working period T. The higher the multiple, the stronger the suppression capability for noise from laser sources other than those in this system, thus making the suppression effect of time "encoding" more significant.

[0087] It should be noted that other embodiments or implementation methods of the anti-noise system for non-system laser sources for DTOF image sensors described in this invention can refer to the above-described method embodiments, and will not be repeated here.

[0088] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0089] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0090] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for resisting non-system laser source noise in a DTOF image sensor, characterized in that, The method includes: The laser source of this system emits optical pulse signals in N working cycles; A certain number of delay intervals are inserted between two adjacent work cycles, and the number of delay intervals inserted between each pair of adjacent work cycles is different; The optical pulse signals of N working cycles after the insertion of the delay interval are accumulated on the histogram to form the corresponding peak values.

2. The method for resisting non-system laser source noise for DTOF image sensors as described in claim 1, characterized in that, The total number of delay intervals inserted during N working weeks and the length of each delay interval remain unchanged.

3. The method for resisting non-system laser source noise for DTOF image sensors as described in claim 1, characterized in that, The insertion of a certain number of delay intervals between two adjacent work cycles includes: n delay intervals are inserted between the nth working cycle and the (n+1)th working cycle, where 1≤n≤N-1.

4. The method for resisting non-system laser source noise for DTOF image sensors as described in claim 1, characterized in that, The insertion of a certain number of delay intervals between two adjacent work cycles includes: Insert m1 delay intervals between the nth working cycle and the (n+1)th working cycle, and insert m2 delay intervals between the (n+1)th working cycle and the (n+2)th working cycle, where m1+m2=N.

5. The method for resisting non-system laser source noise for a DTOF image sensor as described in claim 1, characterized in that, The insertion of a certain number of delay intervals between two adjacent work cycles includes: The number of insertions is m in the nth interval and the Nnth interval, respectively. n and m N-n The delay interval, and m n +m N-n =N.

6. The method for resisting non-system laser source noise for a DTOF image sensor as described in claim 3, characterized in that, The sum of the delays of each stage compared to the previous stage is taken as the total misalignment delay, ta = (N-1). t, where t represents the delay interval, the total misalignment delay ta≥MT, M≥2, and T represents the working cycle.

7. A noise suppression system for non-local laser sources used in DTOF image sensors, characterized in that, The system includes: The optical pulse signal generation module is used by the laser source of this system to emit optical pulse signals according to N working cycles. The delay interval module is used to insert a certain number of delay intervals between two adjacent work cycles, and the number of delay intervals inserted between each pair of adjacent work cycles is different; The receiving quantization module is used to accumulate the optical pulse signals of N working cycles after the insertion of the delay interval on the histogram to form the corresponding peak value.

8. The noise suppression system for non-intrinsic laser sources for a DTOF image sensor as described in claim 7, characterized in that, The total number of delay intervals inserted during N working weeks and the length of each delay interval remain unchanged.

9. The noise suppression system for non-intrinsic laser sources for a DTOF image sensor as described in claim 7, characterized in that, The delay interval module is specifically used for: n delay intervals are inserted between the nth working cycle and the (n+1)th working cycle, where 1≤n≤N-1; Alternatively, m1 delay intervals can be inserted between the nth working cycle and the (n+1)th working cycle, and m2 delay intervals can be inserted between the (n+1)th working cycle and the (n+2)th working cycle, where m1+m2=N; Alternatively, insert a number of m at the nth interval and the Nnth interval respectively. n and m N-n The delay interval, and m n +m N-n =N.

10. The noise suppression system for non-intrinsic laser sources for a DTOF image sensor as described in claim 7, characterized in that, The encoding method used in the delay interval module is to insert n delay intervals between the nth working cycle and the (n+1)th working cycle, where 1≤n≤N-1, and the sum of the delays of each level that are more than the previous level is taken as the total misalignment delay, ta=(N-1). t, where t represents the delay interval, the total misalignment delay ta≥MT, M≥2, and T represents the working cycle.

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