CN113484876B - Laser three-dimensional staring imaging system - Google Patents
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Abstract
The invention discloses a laser three-dimensional staring imaging system, which comprises: the device comprises a pulse laser transmitting module, an echo signal receiving optical system, a phase modulation module, a micro-polarization detection module and an electric delayer; wherein, the pulse laser emission module generates pulse laser; the echo signal receiving optical system shapes the laser signal scattered by the target to be detected into a parallel light echo signal; the phase modulation module performs phase modulation on the parallel light echo signal to obtain a polarized light signal; the micro-polarization detection module obtains phase modulation amount according to the polarization angle of the polarized light signal, obtains a plurality of target distance information according to the one-to-one correspondence relationship between the phase modulation amount and the flight time of the pulse laser, and acquires a target three-dimensional image according to the plurality of target distance information. The invention converts the photon flight time measurement problem into the measurement of phase information, and forms an innovative high-resolution laser three-dimensional staring imaging detection mode by means of the high transverse resolution characteristic of the intensity detector.
Description
Technical Field
The invention belongs to the technical field of remote sensing science and laser three-dimensional imaging, and particularly relates to a laser three-dimensional staring imaging system.
Background
The laser radar is a high and new technology which is rapidly developing, and has wide application in the fields of military use, civil use and the like. The existing high-resolution laser three-dimensional imaging technology mainly adopts a scanning type and a staring type detection system. Scanning type laser three-dimensional imaging radar generally adopts a point scanning mechanism or a line scanning mechanism, and obtains a large amount of point cloud data through large-range circular scanning so as to reconstruct a three-dimensional image. Although the imaging resolution is increased by adopting a scanning mode, the three-dimensional imaging frame frequency is limited, and the engineering technical complexity of the laser radar is improved; (2) The staring type laser three-dimensional imaging radar is a 'parallel' detection mode using staring imaging system instead of a 'serial' detection mode using scanning imaging system, so as to implement parallel synchronous measurement of laser round-trip flight time. Although a complex scanning mechanism is not needed in the method, the method is limited by the pixel number and the timing circuit bandwidth of the current area array timing detector, and even if the most advanced current large-area array laser detector is adopted, the three-dimensional imaging resolution of laser cannot be greatly improved.
In summary, the current laser three-dimensional imaging technology is limited by the number of pixels and bandwidth indexes of a timing detector, and a complex scanning mechanism is often required to be added to improve the resolution, so that the applications of the laser radar in large-area target search, moving target fast imaging, and real-time target identification and tracking are limited. The adoption of a large-area array three-dimensional imaging device is a necessary way for solving the problems of slow updating frequency of the scanning laser radar and realizing the rapid detection of the target.
The existing large-area array APD three-dimensional imager technology is still not mature, and the traditional laser three-dimensional imaging technology adopting the CCD cannot simultaneously realize laser three-dimensional imaging with high precision, high frame frequency and high resolution.
Disclosure of Invention
The technical problem solved by the invention is as follows: the defects in the prior art are overcome, the laser three-dimensional staring imaging system is provided, the problem of photon flight time measurement is converted into phase information measurement by combining laser echo signal phase modulation and micro-polarization array detection, and an innovative high-resolution laser three-dimensional staring imaging detection mode is formed by means of the high transverse resolution characteristic of an intensity detector.
The purpose of the invention is realized by the following technical scheme: a laser three-dimensional gaze imaging system, comprising: the device comprises a pulse laser transmitting module, an echo signal receiving optical system, a phase modulation module, a micro-polarization detection module and an electric delayer; the pulse laser emitting module generates pulse laser, and irradiates a target to be detected after expanding and collimating the pulse laser; the echo signal receiving optical system receives a laser signal scattered by a target to be detected and shapes the laser signal scattered by the target to be detected into a parallel light echo signal; the phase modulation module performs phase modulation on the parallel light echo signal to obtain a polarized light signal; the phase modulation quantity corresponds to the flight time of the pulse laser one by one; the micro-polarization detection module is used for measuring the polarization angle of the polarized light signal, obtaining a phase modulation amount according to the polarization angle of the polarized light signal, obtaining a plurality of target distance information according to the one-to-one correspondence relationship between the phase modulation amount and the flight time of the pulse laser, and acquiring a target three-dimensional image according to the plurality of target distance information; the electric delayer is respectively connected with the micro-polarization detection module and the pulse laser emission module, and is used for controlling the moment when a CCD camera in the micro-polarization detection module starts integration.
In the laser three-dimensional staring imaging system, the pulse laser emitting module comprises a pulse laser and a beam expander; wherein the pulsed laser generates pulsed laser light; and the beam expander expands and collimates the pulse laser and then irradiates the target to be measured.
In the laser three-dimensional staring imaging system, the echo signal receiving optical system is a Cassegrain telescope system.
In the laser three-dimensional staring imaging system, the phase modulation module comprises a linear polarizer, an electro-optic modulation crystal and a quarter wave plate; the linearly polarizing plate converts the parallel light echo signal into a linearly polarized light signal, wherein the polarization direction of the linearly polarized light signal forms 45 degrees with the fast axis and the slow axis of the electro-optic modulation crystal; the electro-optical modulation crystal converts a linear polarization laser signal into an elliptical polarization signal; the quarter-wave plate changes the elliptical polarized light signal into a polarized light signal.
In the laser three-dimensional staring imaging system, the micro-polarization detection module comprises a band-pass filter, a micro-polarization array and a CCD camera; the band-pass filter is used for removing environmental noise in the polarized light signal; the micro-polarization array measures the polarization angle of the polarized light signal without the environmental noise, phase modulation amount is obtained according to the polarization angle, and a plurality of target distance information is obtained according to the one-to-one correspondence relationship between the phase modulation amount and the flight time of the pulse laser; and the CCD camera acquires a target three-dimensional image according to the distance information of the targets.
In the laser three-dimensional staring imaging system, the micro-polarization array comprises a plurality of four-quadrant polarizer sub-arrays, wherein each four-quadrant polarizer sub-array is used for measuring polarization I, Q, U and V components of the polarized light signal for removing the environmental noise, obtaining a polarization angle of the polarized light signal for removing the environmental noise according to the polarization I, Q, U and V components of the polarized light signal for removing the environmental noise, obtaining a phase modulation amount according to the polarization angle, and obtaining target distance information corresponding to the center of each four-quadrant polarizer sub-array according to the one-to-one correspondence relationship between the phase modulation amount and the flight time of the pulse laser.
In the laser three-dimensional staring imaging system, the phase difference between the power supply voltage V (t) of the electro-optical modulation crystal and the e light and o light of the linearly polarized light signal
The relationship between them is:
wherein n is 0 Is the refractive index of o light in the electro-optically modulated crystal, r 63 Is the electrooptic tensor coefficient of the electrooptic modulation crystal, and is the pulse laser wavelength V π Is a half-wave voltage, and t is the flight time of the pulsed laser.
In the laser three-dimensional staring imaging system, each four-quadrant polarizer sub-array consists of four linear polarizer units of 0 degree, 90 degrees, 45 degrees and 135 degrees; wherein, the first and the second end of the pipe are connected with each other,
the intensities of the linear polarization components at 0 °, 45 °, 90 ° and 135 ° are expressed as:
according to I 0 、I 45 、I 90 And I 135 Obtaining the phase modulation amount
Comprises the following steps:
wherein, I 0 Light intensity of linear polarization component of 0 degree, I 45 Light intensity of a linear polarization component of 45 DEG, I 90 Light intensity of linear polarization component of 90 DEG, I 135 Is 135 deg. of light intensity of linearly polarized component.
In the laser three-dimensional staring imaging system, the flight time t and the phase modulation quantity of the pulse laser
The relationship of (c) is:
wherein, T m To modulate the voltage waveform width, τ is the voltage modulation delay time.
In the laser three-dimensional staring imaging system, the target distance information corresponding to the center of each four-quadrant polarizer subarray is obtained through the following formula:
wherein, L is the target distance information corresponding to the center of each four-quadrant polaroid subarray, and c is the speed of light.
Compared with the prior art, the invention has the following beneficial effects:
the distance resolution of the laser three-dimensional staring imaging system is determined by the delay time error of an electric delayer, the width error of a modulation voltage waveform and the fluctuation of an echo signal acquired by a micro-polarization detection component. These errors can be well controlled, so the laser three-dimensional staring imaging system of the invention also has the characteristic of high-precision distance precision.
Drawings
Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:
FIG. 1 is a block diagram of a laser three-dimensional staring imaging system according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a phase modulation assembly according to an embodiment of the present invention;
fig. 3 is a schematic diagram of a polarization state measurement method according to an embodiment of the present invention.
Detailed Description
Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict. The present invention will be described in detail below with reference to the accompanying drawings in conjunction with embodiments.
Fig. 1 is a block diagram of a laser three-dimensional gaze imaging system according to an embodiment of the present invention. As shown in fig. 1, the laser three-dimensional gaze imaging system comprises: the device comprises a pulse laser emitting module, an echo signal receiving optical system, a phase modulation module, a micro-polarization detection module and an electric delayer. Wherein, the first and the second end of the pipe are connected with each other,
the pulse laser emitting module generates pulse laser, and irradiates a target to be measured after expanding and collimating the pulse laser; the echo signal receiving optical system receives a laser signal scattered by a target to be detected and shapes the laser signal scattered by the target to be detected into a parallel light echo signal; the phase modulation module performs phase modulation on the parallel light echo signal to obtain a polarized light signal; the phase modulation quantity corresponds to the flight time of the pulse laser one by one; the micro-polarization detection module is used for measuring the polarization angle of the polarized light signal, obtaining a phase modulation amount according to the polarization angle of the polarized light signal, obtaining a plurality of target distance information according to the one-to-one correspondence relationship between the phase modulation amount and the flight time of the pulse laser, and acquiring a target three-dimensional image according to the plurality of target distance information; the electric delayer is respectively connected with the micro-polarization detection module and the pulse laser emission module, and the electric delayer is used for controlling the moment when a CCD camera in the micro-polarization detection module starts integration.
The pulse laser emitting module comprises a pulse laser and a beam expander; wherein the pulsed laser generates pulsed laser light; and the beam expander expands and collimates the pulse laser and then irradiates the target to be measured. The pulse laser emits 1550nm pulse laser, and a light spot becomes large after passing through the laser beam expander and is used for irradiating a target to be detected.
The echo signal receiving optical system is an optical system consisting of a Cassegrain telescope system and is used for collecting laser signals scattered by a target and shaping the laser signals into parallel beams.
The phase modulation module is arranged behind the signal receiving module and is used for modulating the phase of the laser signal; the phase modulation module is composed of a linear polarizer, an electro-optic modulator and a quarter-wave plate in sequence, wherein the linear polarizer is used for converting a laser echo signal into linearly polarized light, and meanwhile, the polarization direction is ensured to form 45 degrees with the fast axis and the slow axis of the electro-optic modulation crystal. The electro-optical modulator is used for decomposing polarized light into two polarized components of e light and o light through voltage modulation, the phase difference of the e light and the o light can be modulated through controlling voltage, and a linear polarized laser signal modulated by the electro-optical modulator can be changed into elliptically polarized light. The quarter-wave plate is used for converting the elliptical polarized light into polarized light, and the polarization angle of the output polarized light is determined by the phase difference modulated by the electro-optical crystal.
The micro-polarization detection module is arranged behind the phase modulation module and used for measuring the polarization angle of the laser signal, so that the phase modulation amount of the electro-optical modulator is obtained through calculation. The micro-polarization detection module consists of a band-pass filter, a micro-polarization array and a CCD camera; the band-pass filter is a filter with narrower bandwidth and the same central wavelength as the pulse laser and is used for inhibiting environmental noise; the micro-polarization array is composed of a plurality of four-quadrant polarizer sub-arrays, and the four-quadrant polarizer sub-arrays are used for measuring polarization I, Q, U and V components of the laser signals, so that the polarization angle and the phase modulation quantity of the laser signals are calculated. And obtaining target distance information corresponding to the center of the four-quadrant polarizer sub-array according to the corresponding relation between the phase modulation quantity and the photon flight time. The corresponding relation between the phase modulation quantity and the photon flight time needs to be accurately calibrated in a laboratory before the system is used.
Because the micro-polarization array is composed of a plurality of four-quadrant polarizer sub-arrays, each four-quadrant polarizer sub-array can obtain one target distance information, and the micro-polarization detection module can simultaneously obtain a plurality of target distance information, a target three-dimensional image can be constructed. The resolution of the target three-dimensional pattern is determined by the number of the four-quadrant polarizer sub-arrays. Assuming that the CCD pixels used are M × N, (M-1) × (N-1) four-quadrant polarizer sub-arrays can be realized by combination, thereby realizing (M-1) × (N-1) laser three-dimensional imaging. Because each four-quadrant polaroid subarray works simultaneously, the laser three-dimensional staring imaging function with the resolution of (M-1) × (N-1) can be realized.
As shown in fig. 1, a 1550nm pulse laser is used as an active irradiation light source, the 1550nm laser passes through a collimator and expands beam, the diameter of the beam is changed from a 2mm gaussian beam to a 200mm flat-top beam, and the flat-top beam irradiates a target to be measured. The target to be measured has certain directional reflection characteristics, and part of scattered laser enters the field of view of the echo signal receiving optical system. The echo signal receiving optical system adopts a Cassegrain telescope system to collect the light beam of a target and output the light beam to the phase modulation component.
The phase modulation component is composed as shown in fig. 2, and aims to realize phase modulation of echo signals. The phase modulation comprises a linear polarizer, an electro-optic modulation crystal and a quarter wave plate. Wherein the electro-optical modulation crystal satisfies the condition: the clear aperture is large enough not to limit the field of view of the detector; the device has large response bandwidth and meets the time resolution requirement; the high-speed shutter has high-speed shutter triggering capability and provides a range gate adjusting function for ranging. The phase modulation process for the laser echo signal is as follows:
(1) The laser echo signal is changed into linearly polarized light after passing through the linear polarizer, and the fast axis and the slow axis of the electro-optic modulation crystal form 45 degrees with the incident linearly polarized light respectively.
(2) Applying variable voltage along the optical axis of the electro-optical modulation crystal, changing the electro-optical crystal from a uniaxial crystal into a biaxial crystal due to the electro-optical effect, and decomposing linearly polarized light into two polarization components which are vertical to each other: o-light and e-light. When the supply voltage V (t) of the electro-optical crystal is 0, the phase difference between the e light and the o light
Is 0, the phase difference increases with the voltage V (t)
Also varied together.
(3) Linearly polarized light modulated by the electro-optic crystal is changed into elliptically polarized light, the major axis and the minor axis of the elliptically polarized light form 45 degrees relative to the fast axis and the slow axis of the electro-optic modulation crystal, and the ellipticity changes along with the phase difference between the fast axis and the slow axis of the electro-optic modulation crystal.
(4) A quarter-wave plate is placed behind the electro-optic modulation crystal, with the fast and slow axes of the plate also at 45 ° to the fast and slow axes of the EOM. Thus, the elliptically polarized light emitted from the electro-optical modulation crystal is changed into linearly polarized light again through the quarter-wave plate, and the angle of the emitted linearly polarized light depends on the ellipticity or the phase difference generated by the electro-optical modulation crystal.
Phase difference
The voltage V (t) corresponds to the following relationship.
Wherein n is o Is the refractive index of o light in EOM, r 63 Is the electrooptic tensor coefficient of EOM, and λ is the laser wavelength when the phase difference is
The optical path difference of the polarization component is half wavelengthThe corresponding voltage is called half-wave voltage V π . Where τ is the time at which the EOM starts modulation, T m Both these parameters as well as the shape of the V (t) curve can be preset in order to modulate the gate width. The phase change is a function of time when the phase modulation of the laser echo signal is known
Then can be based on
The curve analyzes the arrival time T of the laser echo, and obtains the photon flight time (tau + T) and the distance L of the target.
Linearly polarized light of the laser echo signal after passing through the phase modulation component enters a micro-polarization detection component, and the micro-polarization detection component is composed of an optical filter, a micro-polarizer array and a CCD camera. The filter is a narrow-band filter with the central wavelength consistent with the pulse laser and is used for inhibiting out-of-band stray light. In order to realize the measurement of the polarization state of the laser echo, the polarization intensity information of the laser echo signal at different angles is measured, and a combined method of a four-quadrant detector and a polarization array is adopted to realize synchronous measurement, as shown in fig. 3. The polarizer array consists of four linear polarizer units, namely a horizontal (0 degree), a vertical (90 degree), a left oblique (45 degree) and a right oblique (135 degree), and is aligned with a four-quadrant detector in a high-precision axis mode. Through the combination mode, the phase can be obtained through formula calculation only by once measurement
The intensities of the linear polarization components of horizontal (0 deg.), vertical (90 deg.), 45 deg. and 135 deg. can be expressed as
Combined with formulae (2) to (5), phase
Is calculated by the formula
From the experimental procedures described above, the phase modulation based laser ranging equation can be generalized. The arrival time t and the phase of the laser echo are obtained by assuming that the EOM voltage is modulated by a linear function formula
Is related to the phase of the modulation function.
T m To modulate the voltage waveform width, τ is the voltage modulation delay time, which corresponds to the moment of opening of the gate. According to the relation between the photon flight time and the distance, a laser ranging equation based on phase modulation is constructed as
In the practical engineering application process, the opening time of the distance door is set by adjusting the value of tau according to the distance of the interested target.
For laser three-dimensional staring imaging, a micro-polarization array is adopted to realize differenceAnd measuring the polarized light intensity information with high resolution of the field of view. Suppose the size of the micro-polarization array is m × n, i represents a row and j represents a column. According to the phase modulation distance measurement equation (8), the target distance information of the central point position can be calculated through the intensity information of the adjacent four pixels. For example, by i 1 ，i 2 Row and j 1 ，j 2 And (3) solving the distance of the central point (1) according to the intensity information output by four pixels with intersected columns. Likewise, through i 2 ，i 3 Row and j 1 ，j 2 The intensity information output by the four pixels is used for calculating the distance of the central point (2). By analogy, traversing the m multiplied by n micro-polarization array, the distance information of (m-1) multiplied by (n-1) points in the exploration field can be synchronously obtained, and a laser three-dimensional image of the target is formed.
The system can convert the photon flight time into phase information, and change the phase of the echo signal by modulating the echo signal, and the phase change amount of the echo signal is in one-to-one correspondence with the photon flight time, so the conversion of the photon flight time can be realized by measuring the phase change amount. The four-quadrant detector is used for measuring the light intensity of the echo signal and inverting the phase of the echo signal, the micro-polarization array detection module is used for measuring the phase change amount of the echo signal, and the phase information is calculated by measuring the polarization information I, Q, U and V of the echo signal. Since the relationship between the phase and the flight time of the echo signal is determined, the target distance information can be inverted through the phase information, thereby constructing a light intensity I → phase
→ distance L ″.
The laser ranging precision of the invention is not determined by the laser pulse width and the time resolution of a circuit system like the traditional laser ranging, and the distance resolution of the laser three-dimensional staring imaging system of the invention is determined by the delay time error of an electric delayer, the width error of a modulation voltage waveform and the fluctuation of an echo signal acquired by a micro-polarization detection component. These errors can be well controlled, so the laser three-dimensional staring imaging system of the invention also has the characteristic of high-precision distance precision.
Although the present invention has been described with reference to the preferred embodiments, it is not intended to limit the present invention, and those skilled in the art can make variations and modifications of the present invention without departing from the spirit and scope of the present invention by using the methods and technical contents disclosed above.
Claims (6)
1. A laser three-dimensional gaze imaging system, comprising: the device comprises a pulse laser transmitting module, an echo signal receiving optical system, a phase modulation module, a micro-polarization detection module and an electric delayer; wherein the content of the first and second substances,
the pulse laser emitting module generates pulse laser, and irradiates a target to be measured after expanding and collimating the pulse laser;
the echo signal receiving optical system receives a laser signal scattered by a target to be detected and shapes the laser signal scattered by the target to be detected into a parallel light echo signal;
the phase modulation module performs phase modulation on the parallel light echo signal to obtain a polarized light signal; the phase modulation quantity corresponds to the flight time of the pulse laser one by one;
the micro-polarization detection module is used for measuring the polarization angle of the polarized light signal, obtaining phase modulation quantity according to the polarization angle of the polarized light signal, obtaining a plurality of target distance information according to the one-to-one correspondence relationship between the phase modulation quantity and the flight time of the pulse laser, and acquiring a target three-dimensional image according to the plurality of target distance information;
the electric delayer is respectively connected with the micro-polarization detection module and the pulse laser emission module and is used for controlling the moment when a CCD (charge coupled device) camera in the micro-polarization detection module starts integration;
the phase modulation module comprises a linear polarizer, an electro-optic modulation crystal and a quarter-wave plate; wherein the content of the first and second substances,
the linear polarizer converts the parallel light echo signal into a linearly polarized light signal, wherein the polarization direction of the linearly polarized light signal forms an angle of 45 degrees with the fast axis and the slow axis of the electro-optic modulation crystal;
the electro-optical modulation crystal converts a linear polarization laser signal into an elliptical polarization signal;
the quarter-wave plate changes the elliptical polarized light signal into a polarized light signal;
the micro-polarization detection module comprises a band-pass filter, a micro-polarization array and a CCD camera; wherein the content of the first and second substances,
the band-pass filter is used for removing environmental noise in the polarized light signal;
the micro-polarization array measures the polarization angle of the polarized light signal without the environmental noise, phase modulation amount is obtained according to the polarization angle, and a plurality of target distance information is obtained according to the one-to-one correspondence relationship between the phase modulation amount and the flight time of the pulse laser;
the CCD camera acquires a target three-dimensional image according to the information of the distance of the targets;
the micro-polarization array comprises a plurality of four-quadrant polarizer subarrays, wherein each four-quadrant polarizer subarray is used for measuring polarization I, Q, U and V components of the polarized light signal without the environmental noise, obtaining a polarization angle of the polarized light signal without the environmental noise according to the polarization I, Q, U and V components of the polarized light signal without the environmental noise, obtaining a phase modulation amount according to the polarization angle, and obtaining target distance information corresponding to the center of each four-quadrant polarizer subarray according to the one-to-one correspondence relationship between the phase modulation amount and the flight time of pulse laser;
the target distance information corresponding to the center of each four-quadrant polarizer sub-array is obtained through the following formula:
wherein L is target distance information corresponding to the center of each four-quadrant polaroid subarray, c is light speed, and T is m For modulating the voltage waveform width, τ is the voltage modulation delay time, I 0 Light intensity of linear polarization component of 0 degree, I 45 Light intensity of linear polarization component of 45 DEG, I 90 Light intensity of linear polarization component of 90 DEG, I 135 Is 135 deg. of light intensity of linearly polarized component.
2. The laser three-dimensional gaze imaging system of claim 1, wherein: the pulse laser emitting module comprises a pulse laser and a beam expander; wherein the pulsed laser generates pulsed laser light; and the beam expander expands and collimates the pulse laser and irradiates the target to be detected.
3. The laser three-dimensional gaze imaging system of claim 1, wherein: the echo signal receiving optical system is a Cassegrain telescopic system.
4. The laser three-dimensional gaze imaging system of claim 1, wherein: phase difference between power supply voltage V (t) of electro-optical modulation crystal and e light and o light of linearly polarized light signal
The relationship between them is:
wherein n is 0 Is the refractive index of o light in the electro-optical modulation crystal, r 63 Is the electrooptic tensor coefficient of the electrooptic modulation crystal, wherein lambda is the pulse laser wavelength, V π Is a half-wave voltage, and t is the flight time of the pulsed laser.
5. The laser three-dimensional gaze imaging system of claim 1, wherein: each four-quadrant polarizer sub-array is composed of four linear polarizer units of 0 degree, 90 degrees, 45 degrees and 135 degrees; wherein the content of the first and second substances,
the intensities of the linear polarization components at 0 °, 45 °, 90 ° and 135 ° are expressed as:
according to I 0 、I 45 、I 90 And I 135 Obtaining the phase modulation amount
Comprises the following steps:
wherein, I 0 Intensity of a linearly polarized component of 0 DEG, I 45 Light intensity of linear polarization component of 45 DEG, I 90 Light intensity of linear polarization component of 90 DEG, I 135 Is a linear polarized component light intensity of 135 deg..
6. The laser three-dimensional gaze imaging system of claim 5, wherein: time of flight t and phase modulation amount of pulse laser
The relationship of (c) is:
wherein, T m To modulate the voltage waveform width, τ is the voltage modulation delay time.
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