CN113156409B - Direct sequence time correlation photon counting error compensation method - Google Patents
Direct sequence time correlation photon counting error compensation method Download PDFInfo
- Publication number
- CN113156409B CN113156409B CN202110370741.9A CN202110370741A CN113156409B CN 113156409 B CN113156409 B CN 113156409B CN 202110370741 A CN202110370741 A CN 202110370741A CN 113156409 B CN113156409 B CN 113156409B
- Authority
- CN
- China
- Prior art keywords
- value
- error
- photon
- depth
- photon counting
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
- G01S7/497—Means for monitoring or calibrating
Landscapes
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Optical Radar Systems And Details Thereof (AREA)
Abstract
The invention discloses a direct sequence time correlation photon counting error compensation method which specifically comprises the following steps of correcting a photon counting value R detected by a pixel corresponding to an x-th row and a y-th column through area array scanningdetect(x, y) according to the formulaCalculating the corrected photon count value, and adjusting the fixed optical attenuator corresponding to the A Geiger mode avalanche diode to obtain the corrected photon count value R of the A Geiger mode avalanche diode arrival time recorderactual(x, y) is equal to the number of the direct sequence code as 1, and is used as a reference path photon counting value which is marked as RbaseGradually reducing the light intensity of the reflected echoes by adjusting a polaroid and a variable optical attenuator to obtain N groups of reflected echoes with different light intensities, and recording the photon number of the ith group of reflected echoes detected by the B Geiger mode avalanche diode as Rdet(i) The direct sequence time correlation photon counting error compensation method can compensate depth errors in real time with high precision, correct depth images and further improve measurement accuracy.
Description
Technical Field
The invention relates to the technical field of laser ranging, in particular to a direct sequence time correlation photon counting error compensation method.
Background
In recent years, research on direct sequence time-dependent photon counting type depth imaging systems has been widely conducted.
Firstly, the existing system adopts a method of emitting a direct sequence at one path and generating a synchronous high level at the other path for detection, and the technology has the problems that high level pulses often cannot be completely synchronous with the time of starting code sending, and particularly when a high code stream rate is sent, the asynchronism can bring about the offset of code pattern reconstruction, thereby causing the problems of broadening of time correlation function waveform, lowering of depth accuracy and the like; in some systems that use an additional pll to solve the synchronization problem, the complexity of the hardware system is increased.
Secondly, the accuracy of the system is also one of key performance parameters, and due to environmental factors, such as noise and uncertain factors such as target materials, a direct sequence time-dependent photon counting type depth imaging method inevitably has measurement errors, and reports indicate that the main reason of the errors is that a photon detector has time walking errors or time jitter, namely, the more photons are detected in unit time, the larger the generated time arrival point advance is, the lower the system accuracy is, in the system, the time walking effect of a Geiger mode avalanche diode causes the deviation of a plurality of photon time arrival points, and inevitably brings the integral displacement of a time-dependent function, so that an offset compensation method of the system is necessary; the offset compensation threshold comparison circuit aiming at the Geiger mode avalanche diode is too complex and has poor applicability; simple function fitting methods (e.g., Weiji He, Bo yu Si ma, Yun fei Chen, Hui dong Dai, Qian Chen, Guo hua Gu. A correction method for range walk error in photosonic counting 3D imaging LIDAR [ J ]. Optics Communications, 2013, 308(1):211-217.Shanshan Shen shen, Chen Qian, Weiji, et al. Boundayevaluation and error correction on Pseudo-random spread spectrum counting system [ J ]. ChineOptics Letters, 2017, 15(9): 090101-1-101-6.). Although the depth accuracy can be improved, the depth offset variances of low signal-to-noise ratio and high signal-to-noise ratio have obvious mutual difference, the variance of each component of the least square estimation quantity of the parameters is large, so that the fluctuation of the estimated value and the true value is increased, namely the variance in the model is no longer minimum, the estimation accuracy is reduced, and the correction of photon counting rate is not considered, so that the method has poor effect in actual imaging.
Disclosure of Invention
This section is for the purpose of summarizing some aspects of embodiments of the invention and to briefly introduce some preferred embodiments. In this section, as well as in the abstract and the title of the invention of this application, simplifications or omissions may be made to avoid obscuring the purpose of the section, the abstract and the title, and such simplifications or omissions are not intended to limit the scope of the invention.
The present invention has been made in view of the above and/or other problems with the prior art direct sequence time-dependent photon counting depth imaging systems.
Therefore, an object of the present invention is to provide a method for compensating a direct sequence time-dependent photon counting error, which can compensate a depth error in real time with high accuracy, and further improve system accuracy.
To solve the above technical problem, according to an aspect of the present invention, the present invention provides the following technical solutions:
a direct sequence time correlation photon counting error compensation method comprises the following specific steps:
s1, correcting the photon count value R detected by the pixel corresponding to the x-th row and the y-th column through area array scanningdetect(x, y) calculating corrected photon count value R according to equation (1)actual(x,y)；
Ractual(x,y)＝Rdetect(x,y)Corr(x,y)-darkcounts (1)
Wherein dark counts are dark counts;
corr (x, y) is the photon counting rate correction coefficient, dtIs the dead time;
s2, adjusting the fixed light attenuator corresponding to the A Geiger mode avalanche diode to correct the photon count value R of the A Geiger mode avalanche diode arrival time recorderactual(x, y) is equal to the number of 1 in the direct sequence as the photon counting value of the reference path, and is marked as Rbase；
S3, gradually reducing the light intensity of the reflected echoes by adjusting the polaroid and the variable optical attenuator to obtain N groups of reflected echoes with different light intensities, recording the photon number of the ith group of reflected echoes detected by the B Geiger mode avalanche diode, and calculating the corrected photon count value according to the formula (1) and recording the corrected photon count value as Rdet(i) Wherein i is more than 0 and less than or equal to N;
s4, calculating the photon counting proportion after the i-th group of correction
S5, reconstructing two photon time arrival points x (n), y (n) of the A Geiger mode avalanche diode and the B Geiger mode avalanche diode, and calculating to obtain a relevant photon count value corresponding to the nth time unit, which is also called as a time correlation function:
s6, under the condition of calculating the photon counting proportion of the 1 st group of experiment, the centroid fitting depth value of 50 points is respectively taken at the left and the right of the peak value of the time correlation function
Wherein τ (n) is the photon time-of-flight value for the nth time cell;
s7, repeating the steps S3-S6 until the detected time-dependent function wave is seriously distorted, recording the photon counting proportion value R (N) of the previous distortion, namely the Nth time and the corresponding depth value d (N), and recording the photon counting proportion value R (N) and the depth value d (N) as the depth reference value dreference；
S8, obtaining N groups of depth values d (i) (1 ≦ i ≦ N) and reference depth value dreferenceSubtracting to obtain depth error value d under corresponding photon counting ratio R (i)error[R(i)]Namely:
derror[R(i)]＝dreference-d(i)；
s9, calculating the depth value d after compensationcorrect＝d(i)+derror[R(i)]；
S10, obtaining an original depth matrix d (x, y) according to the corresponding pixels of the x row and the y column, and substituting the corrected photon counting proportion matrix R (x, y) into the formula of the step S9,
obtaining a compensated depth image as dcorrect(x,y)＝d(x,y)+derror[R(x,y)]。
As a preferable embodiment of the direct sequence time-dependent photon counting error compensation method according to the present invention, in the step S8, derror[R(i)]＝dreferenceThe specific calculation steps of-d (i) are:
s8.1, calculating a depth value by adopting the centroid fitting algorithm in the step S6, and combining a corresponding photon counting proportional value to form original data with prior information;
s8.2 setting N groups of distance error values derror(i) (1. ltoreq. i.ltoreq.N), N sets of photon count ratios R (i) (1. ltoreq. i.ltoreq.N) satisfying the functional expression with a coefficient a:
where a is an unknown parameter and has a length k, i.e. a ═ a1,…,ak]And observing the value derrorThe model parameter a is in a nonlinear relation;
converting the model into a calculation formula
Minimum value of (d);
s8.3 estimating data by using linear least square method
And calculating the residual error
S8.4 calculating the leverage
Mean value, h, representing depth erroriiThe distance between the ith observed value and the average value is represented, because the observed point of the large lever value is far away from the center of the sample, the residual error of the large lever value is small, and the influence of heteroscedasticity on the estimation precision is reduced by adjusting the weight;
s8.5 gives the adjusted residual expression:
s8.6 calculating the weight wi＝1/e(i)2；
S8.7 introducing the adjusted weight wiCalculating a suitable coefficient a such that
And is minimal.
As a preferable scheme of the direct sequence time correlation photon counting error compensation method, in step S1, the area array scanning specifically includes the following steps: the collimator is fixed on a two-dimensional guide rail platform, the operation of the two-dimensional guide rail is controlled in real time based on labview, the two-dimensional guide rail is controlled to move up and down, the collimator is driven by controlling the maximum stroke and the minimum step length of the guide rail, point-by-point scanning is carried out, light pulse signals are collected, time correlation function waveforms are calculated point-by-point, and a two-dimensional depth image is obtained.
As a preferable solution of the direct sequence time-dependent photon counting error compensation method of the present invention, in step S5, the specific steps of two photons reaching the a geiger mode avalanche diode and the B geiger mode avalanche diode are as follows:
the direct sequence generator based on the programmable logic device selects and sends a direct sequence of 2.5GHz to drive the vertical surface laser to emit a light signal;
the optical signal is divided into two paths through a 1-to-2 optical splitter, wherein one path is used as a reference signal and is coupled into an A Geiger mode avalanche diode through a fixed optical attenuator, the other path is used as a transmitting pulse and is led into an A port of an optical circulator through a multimode optical fiber, then the transmitting pulse is led out from a B port of the optical circulator and is transmitted to a target through a collimator, a reflected echo is formed by the target and is re-led into the B port of the optical circulator through the collimator, and then the reflected echo is led out from a C port of the optical circulator and is led into the B Geiger mode avalanche diode through a variable optical attenuator.
As a preferable scheme of the direct sequence time-dependent photon counting error compensation method, the direct sequence is generated by using Matlab.
Compared with the prior art, the invention has the beneficial effects that: according to the direct sequence time correlation photon counting error compensation method, the number of detected photons is corrected in real time, a weighted least square fitting method is adopted based on a linear regression model to obtain a depth offset function, the depth error is compensated in real time with high precision, a more accurate depth image is obtained, and compared with the depth image compensated by the traditional least square method, the system precision is further improved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and detailed embodiments, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without inventive labor. Wherein:
FIG. 1 is a system diagram of a direct sequence time-dependent photon counting error compensation method according to the present invention;
FIG. 2 is a flow chart of a direct sequence time-dependent photon counting error compensation method of the present invention;
FIG. 3 is a depth compensation curve of a direct sequence time-dependent photon counting error compensation method of the present invention;
FIG. 4 is a diagram of a target object of a direct sequence time-dependent photon counting error compensation method of the present invention;
FIG. 5 is an image before compensation of a direct sequence time-dependent photon counting error compensation method according to the present invention;
FIG. 6 is an image of a direct sequence time-dependent photon counting error compensation method according to the present invention.
FIG. 7 is an image of a compensated image according to the prior art method of the present invention.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention more comprehensible, embodiments accompanying figures are described in detail below.
Next, the present invention will be described in detail with reference to the drawings, wherein for convenience of illustration, the cross-sectional view of the device structure is not enlarged partially according to the general scale, and the drawings are only examples, which should not limit the scope of the present invention. In addition, the three-dimensional dimensions of length, width and depth should be included in the actual fabrication.
In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
The invention provides a direct sequence time correlation photon counting error compensation method which can compensate depth errors in real time with high precision and further improve system accuracy.
Fig. 1 is a system diagram corresponding to the direct sequence time-dependent photon counting error compensation method of the present invention, and please refer to fig. 1, the system includes a direct sequencer, a laser, a splitter, an optical circulator, a collimator, a two-dimensional guideway, a fixed attenuator, an adjustable attenuator, an a geiger mode avalanche diode, a B geiger mode avalanche diode, and a time recorder.
The following describes the specific steps of the direct sequence time-dependent photon counting error compensation method according to the present invention in detail with reference to fig. 1.
A direct sequence time correlation photon counting error compensation method comprises the following specific steps:
s1, correcting the detected photon count value R of the pixel corresponding to the x-th row and the y-th column through area array scanningdetect(x, y) calculating according to a formula to obtain a corrected photon count value
Ractual(x,y)＝Rdetect(x, y) Corr (x, y) -dark counts;
corr (x, y) is the photon count rate correction factor, dtIs dead time; preferably, in this embodiment, the area array scanning specifically includes the following steps: the collimator is fixed on the two-dimensional guide rail platform, the two-dimensional guide rail is controlled to work in real time based on labview, the two-dimensional guide rail is controlled to move up and down, and the collimator is driven by controlling the maximum stroke and the minimum step length of the guide railAnd the straightener scans point by point, collects light pulse signals, calculates time correlation function waveforms point by point and obtains a two-dimensional depth image.
S2, adjusting the fixed optical attenuator corresponding to the A Geiger mode avalanche diode to enable the corrected photon count value R of the A Geiger mode avalanche diode to reach the time recorderactual(x, y) is equal to the number of codes 1 in the direct sequence, and is used as a reference path photon counting value which is marked as Rbase；
S3, gradually reducing the light intensity of the reflected echoes by adjusting the polaroid and the variable optical attenuator to obtain N groups of reflected echoes with different light intensities, and setting the photon number of the ith group of reflected echoes detected by the B Geiger mode avalanche diode as Rdet(i) Wherein i is more than 0 and less than or equal to N;
s4, calculating the photon counting ratio after the i group of correction
S5, reconstructing two paths of photon time arrival points x (n), y (n) of the photons arriving at the A Geiger mode avalanche diode and the B Geiger mode avalanche diode, and calculating to obtain a related photon count value corresponding to the nth depth unit
preferably, in this embodiment, the specific steps of two photons reaching the a geiger mode avalanche diode and the B geiger mode avalanche diode are as follows:
the direct sequence generator based on the programmable logic device selects and sends a direct sequence of 2.5GHz to drive the vertical surface laser to emit a light signal;
an optical signal is divided into two paths through a 1-in-2 optical splitter, wherein one path is used as a reference signal and is coupled into an A Geiger mode avalanche diode through a fixed optical attenuator, the other path is used as a transmitting pulse and is guided into an A port of an optical circulator through multimode optical fibers, then the transmitting pulse is guided out from a B port of the optical circulator and is transmitted to a target through a collimator, a reflecting echo is formed by the target and is guided into a B port of the optical circulator again through the collimator, and then the reflecting echo is guided out from a C port of the optical circulator and is guided into the B Geiger mode avalanche diode through a variable optical attenuator. The direct sequence was generated using Matlab.
S6, under the condition of calculating the photon counting proportion of the 1 st group of experiment, the centroid fitting depth value of 50 points is respectively taken at the left and the right of the peak value of the time correlation function
Wherein τ (n) is the photon time-of-flight value for the nth depth cell;
s7, repeating the steps S3-S6 until the detected time-dependent function waveform is seriously distorted, recording the photon counting ratio R (N) of the previous time of distortion, namely the Nth time and the corresponding depth value d (N), and recording the value as the depth reference value dreference(ii) a In the present embodiment, the photon count ratio value R (36) and the corresponding depth value d (36) of the 36 th experiment, which is the previous time of distortion, are recorded, and the photon count ratio of the 36 th experiment is 3 × 104/1.3×106。
S8, obtaining N groups of depth values d (i) (1 ≦ i ≦ N) and reference depth value dreferenceSubtracting to obtain depth error value d under corresponding photon counting ratio R (i)error[R(i)]Namely:
derror[R(i)]＝dreference-d(i)；
in the present embodiment, the 36 sets of depth values d (i) obtained by the experiment and the reference depth value dreferenceSubtracted, resulting in the circular data points of FIG. 3
Preferably, in the present embodiment, derror[R(i)]＝dreferenceThe specific calculation steps of d (i) are:
obtaining a depth value in real time by adopting a centroid fitting algorithm, and combining corresponding photon counting proportional values to form original data with prior information;
there are 36 sets of distance error values derror(i) (1. ltoreq. i.ltoreq.36) there are 36 photon count ratios R (i) (1. ltoreq. i.ltoreq.36) and both satisfy the functional formula with a coefficient a:
where a is an unknown parameter and has a length of 4, i.e. a ═ a1,…,a4]And observing the value derrorAnd has a non-linear relationship with the model parameter a.
Converting the model into a calculation formula
Is measured.
Data estimated using linear least squares
And calculating the residual error
Estimating an original model by adopting a least square method to obtain approximate estimators e (i) of random error terms;
calculating a leverage value
Mean value, h, representing the distance erroriiThe distance between the ith observed value and the independent variable average value is represented, and because the observed point of the large lever value is far away from the center of the sample, the residual error of the large lever value is smaller. The influence of the heteroscedasticity on the estimation precision is reduced by adjusting the weight.
Giving the adjusted residual expression:
calculating the weight wi＝1/e(i)2；
Introducing adjusted weight wiCalculating a suitable coefficient a such that
And minimum. Estimating to obtain a third-order polynomial function by adopting a least square estimation method
derror[R(i)]＝1.1×10-5R(i)3-5.1×10-4R(i)2+0.0107R(i)+0.0034
S9, calculating the depth value d after compensationcorrect＝d(i)+derror[R(i)]；
S10, obtaining an original depth matrix d (x, y) according to the corresponding pixels of the x-th row and the y-th column, and substituting the corrected photon counting proportion matrix R (x, y) into the formula of the step S9,
obtaining a compensated depth image as dcorrect(x,y)＝d(x,y)+derror[R(x,y)]。
The calibration experiment images a planar target about 7 meters away from the system, and the target consists of black and white parts, as shown in fig. 4. The rough black paper and the smooth bright white flat plate form an image, the photon counting rate returned by the smooth bright white plane in the two areas is high, and the photon counting rate returned by the rough black plane is low. Fig. 5 is a depth image measured at an integration time of 0.05 second, and the imaging difference of the black and white areas is represented as: the depth floating degree is different and the depth numerical value walking error is different. After correcting the photon counting value, the photon counting ratio of the time correlation function waveform of the black target is 0.12, and the photon counting ratio of the time correlation function waveform of the white target is 0.89. According to the compensation algorithm flow shown in fig. 2, an original depth matrix d (x, y) and a photon counting proportion matrix R (x, y) of a pixel point are obtained through two-dimensional point-by-point scanning, a depth error value is obtained through calculation of the photon counting proportion R (x, y), a compensated depth image obtained through calculation of the depth error value is shown in fig. 6, and relative depth errors on black and white sides are reduced; fig. 7 is a depth image compensated using a conventional least squares method, with a greater depth error than the method proposed herein. Under the integration time of 0.05 second, the mean square error of the depth before the improvement is 0.11 meter, and the mean square error of the depth after the improvement is reduced to 0.02 meter; and the mean square error of the improved depth of the depth image compensated by the traditional least square method is reduced to 0.04 meter. The depth error of the method is reduced by 4.5 times, and the depth error of the traditional method is reduced by 1.8 times. The method is superior to the conventional method.
It needs to be added that: in this embodiment, it is assumed that the a reference path time arrival point is approximately the original code pattern, and the photon counting rate is fixed. If the photon count rate of the reference pattern changes, a new depth offset is introduced under the same circumstances, this embodiment with a photon count of 1.4 × 10 for the a geiger mode avalanche diode6And taking the photon counting ratio of the B Geiger mode avalanche diode of the receiving path as a controllable variable, representing the energy change of the target reflection echo, and constructing a depth deviation compensation device caused by the energy change of the return echo caused by the material change of the target.
While the invention has been described above with reference to an embodiment, various modifications may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In particular, the various features of the disclosed embodiments of this invention can be used in any combination as long as there is no structural conflict, and the combination is not exhaustively described in this specification merely for the sake of brevity and resource savings. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.
Claims (4)
1. A direct sequence time correlation photon counting error compensation method is characterized by comprising the following specific steps:
s1, correcting the photon count value R detected by the corresponding pixel of the x-th row and the y-th column through area array scanningdetect(x, y) calculating corrected photon count value R according to equation (1)actual(x,y)；
Ractual(x,y)＝Rdetect(x,y)Corr(x,y)-darkcounts (1)
Wherein dark counts are dark counts;
corr (x, y) is the photon counting rate correction coefficient, dtIs the dead time;
s2, adjusting the fixed light attenuator corresponding to the A Geiger mode avalanche diode to correct the photon count value R of the A Geiger mode avalanche diode arrival time recorderactual(x, y) equals the number of 1 s in the direct sequence as the reference path photon count value, denoted as Rbase；
S3, gradually reducing the light intensity of the reflected echoes by adjusting the polaroid and the variable optical attenuator to obtain N groups of reflected echoes with different light intensities, recording the photon number of the ith group of reflected echoes detected by the B Geiger mode avalanche diode, and calculating the corrected photon count value according to the formula (1) and recording the photon count value as Rdet(i) Wherein i is more than 0 and less than or equal to N;
s4, calculating the photon counting ratio after the i group of correction
S5, reconstructing two photon time reaching points x (n), y (n) of the A Gege mode avalanche diode and the B Gege mode avalanche diode, and calculating to obtain a relevant photon count value corresponding to the nth time unit, which is also called as a time correlation function:
wherein, the first and the second end of the pipe are connected with each other,
which is indicative of the fourier transform,
is inverse Fourier transform;
s6, calculating group 1 factUnder the counting proportion of the optometry photons, the centroid fitting depth value of 50 points is respectively taken at the left and the right of the peak value of the time correlation function
Wherein τ (n) is the photon time-of-flight value for the nth time cell;
s7, repeating the steps S3-S6 until the detected time-dependent function wave is seriously distorted, recording the photon counting proportion value R (N) of the previous time of distortion, namely the Nth time and the corresponding depth value d (N), and recording the photon counting proportion value R (N) as the depth reference value dreference；
S8, obtaining N groups of depth values d (i) (1 ≦ i ≦ N) and reference depth value dreferenceSubtracting to obtain depth error value d under corresponding photon counting ratio R (i)error[R(i)]Namely:
derror[R(i)]＝dreference-d(i)；
s9, calculating the depth value d after compensationcorrect＝d(i)+derror[R(i)]；
S10, obtaining an original depth matrix d (x, y) according to the corresponding pixels of the x row and the y column, and substituting the corrected photon counting proportion matrix R (x, y) into the formula of the step S9,
obtaining a compensated depth image as dcorrect(x,y)＝d(x,y)+derror[R(x,y)]；
Wherein, in the step S8, derror[R(i)]＝dreferenceThe specific calculation steps of-d (i) are:
s8.1, calculating a depth value by adopting the centroid fitting algorithm in the step S6, and combining a corresponding photon counting proportional value to form original data with prior information;
s8.2 setting N groups of distance error values derror(i) (1. ltoreq. i.ltoreq.N), N sets of photon count ratios R (i) (1. ltoreq. i.ltoreq.N) and both satisfy the functional formula with coefficient a:
where a is an unknown parameter and has a length k, i.e. a ═ a1,…,ak]And observed valuederrorThe model parameter a is in a nonlinear relation;
conversion of model into calculation formula
Minimum value of (d);
s8.3 estimating data by using a linear least square method
And calculating the residual error
S8.4 calculating the leverage
Mean value, h, representing depth erroriiThe distance between the ith observed value and the average value is represented, because the observed point of the large lever value is far away from the center of the sample, the residual error of the large lever value is small, and the influence of heteroscedasticity on the estimation precision is reduced by adjusting the weight;
s8.5 gives the adjusted residual expression:
s8.6 calculating the weight wi＝1/e(i)2；
S8.7 introducing an adjusted weight wiCalculating a suitable coefficient a such that
And is minimal.
2. The direct sequence time correlation photon counting error compensation method according to claim 1, wherein in the step S1, the area array scanning specifically comprises the following steps: the collimator is fixed on a two-dimensional guide rail platform, the operation of the two-dimensional guide rail is controlled in real time based on labview, the two-dimensional guide rail is controlled to move up and down, the collimator is driven by controlling the maximum stroke and the minimum step length of the guide rail, point-by-point scanning is carried out, light pulse signals are collected, time correlation function waveforms are calculated point-by-point, and a two-dimensional depth image is obtained.
3. The method for compensating the direct sequence time correlation photon counting error of claim 1, wherein in the step S5, the steps of two photons reaching the a geiger mode avalanche diode and the B geiger mode avalanche diode are as follows:
the direct sequence generator based on the programmable logic device selects and sends a direct sequence of 2.5GHz to drive the vertical surface laser to emit a light signal;
the optical signal is divided into two paths through a 1-to-2 optical splitter, wherein one path is used as a reference signal and is coupled into an A Geiger mode avalanche diode through a fixed optical attenuator, the other path is used as a transmitting pulse and is led into an A port of an optical circulator through a multimode optical fiber, then the transmitting pulse is led out from a B port of the optical circulator and is transmitted to a target through a collimator, a reflected echo is formed by the target and is re-led into the B port of the optical circulator through the collimator, and then the reflected echo is led out from a C port of the optical circulator and is led into the B Geiger mode avalanche diode through a variable optical attenuator.
4. The method of claim 3, wherein the direct sequence is generated using Matlab.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110370741.9A CN113156409B (en) | 2021-04-07 | 2021-04-07 | Direct sequence time correlation photon counting error compensation method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110370741.9A CN113156409B (en) | 2021-04-07 | 2021-04-07 | Direct sequence time correlation photon counting error compensation method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN113156409A CN113156409A (en) | 2021-07-23 |
| CN113156409B true CN113156409B (en) | 2022-07-15 |
Family
ID=76888549
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110370741.9A Active CN113156409B (en) | 2021-04-07 | 2021-04-07 | Direct sequence time correlation photon counting error compensation method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113156409B (en) |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103064076B (en) * | 2012-12-26 | 2014-06-25 | 南京理工大学 | System and method for correction of distance walking error of photon counting three-dimensional imaging laser radar |
| CN107015233B (en) * | 2017-05-10 | 2023-12-29 | 南京理工大学紫金学院 | Integrated optical fiber type pseudo-random code amplitude modulation offset correction device |
| CN111679290B (en) * | 2020-06-04 | 2023-05-05 | 上海禾赛科技有限公司 | Photon count correction method, laser radar, and computer-readable medium |
-
2021
- 2021-04-07 CN CN202110370741.9A patent/CN113156409B/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| CN113156409A (en) | 2021-07-23 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN104101880A (en) | Optical distance measuring apparatus | |
| JP2019516114A (en) | Laser ranging system by time domain waveform matching and method thereof | |
| CN110168398B (en) | Flying time ranging system and correction method | |
| WO2021189794A1 (en) | Time of flight ranging system and ranging method therefor | |
| EP3835820A1 (en) | Phase angle correction value calculation apparatus and method of calculating a phase angle correction value | |
| CN105675633B (en) | A kind of caliberating device of X-ray framing camera | |
| CN111352120B (en) | Flight time ranging system and ranging method thereof | |
| CN114488174B (en) | Ranging system and method based on double-channel single photon detection and two-dimensional cross correlation | |
| CN102486402A (en) | Method and system for measuring pulse laser energy | |
| CN112505719A (en) | Laser wind measuring radar wind measuring method and system with Doppler frequency correction secondary compensation | |
| CN111366943B (en) | Flight time ranging system and ranging method thereof | |
| CN113203475A (en) | High-efficiency high-resolution depth reconstruction method for photon counting number | |
| US11561291B2 (en) | High pulse repetition frequency lidar | |
| Chen et al. | A correction method for range walk error in time-correlated single-photon counting using photomultiplier tube | |
| CN113156409B (en) | Direct sequence time correlation photon counting error compensation method | |
| CN110807813B (en) | TOF module calibration method, device and system | |
| CN112532970B (en) | Tap non-uniformity correction method and device of multi-tap pixel sensor and TOF camera | |
| CN115616608A (en) | Single-photon three-dimensional imaging distance super-resolution method and system | |
| CN210119571U (en) | Active imaging system for inhibiting laser light intensity fluctuation image quality degradation effect | |
| CN112946602A (en) | Multipath error compensation method and multipath error compensated indirect time-of-flight distance calculation device | |
| CN111830523A (en) | Photoelectric detector flight time correction system and method | |
| CN113393509B (en) | Laser radar multipath compensation method | |
| CN116559822B (en) | Method and system for detecting laser ranging signals by code pulse shift accumulation | |
| CN112213711B (en) | Calibration method of TOF camera | |
| WO2022172690A1 (en) | Grayscale image generation device, grayscale image correction method, and grayscale image correction program |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |