CN-121978710-A - Pulse phase shift based range gate imaging system

CN121978710ACN 121978710 ACN121978710 ACN 121978710ACN-121978710-A

Abstract

The invention discloses a distance gating imaging system based on pulse phase shift, which comprises a digital control unit, M laser pulse signals, a shutter control signal, M laser driving modules, M groups of laser diodes and an optical fiber beam combiner, wherein the digital control unit is used for generating the M laser pulse signals and the shutter control signal, the M groups of laser diodes and the optical fiber beam combiner are used for combining laser beams output by the laser diodes of each group, the imaging unit receives the shutter control signal and comprises an image intensifier and a driving module thereof for gating and imaging a target under the control of the shutter control signal, M is more than or equal to 2, the repetition frequency of the laser pulse signals is the same but the phase difference exists, each laser driving module is respectively connected with one laser pulse signal output end of the digital control unit, each group of laser diodes is connected with one laser driving module, and each group of laser diodes outputs laser under the driving of the corresponding laser pulse signals.

Inventors

WANG YUBIN
HU JIADONG
HAN HAOBIN
XIA HAIYUN

Assignees

南京信息工程大学

Dates

Publication Date: 20260505
Application Date: 20260407

Claims (9)

1. A distance gating imaging system based on pulse phase shift is characterized by comprising a digital control unit, M laser pulse signals and shutter control signals, M laser driving modules, M groups of laser diodes and an optical fiber beam combiner, wherein the M laser driving modules, the M groups of laser diodes and the optical fiber beam combiner are used for combining lasers output by the laser diodes, the imaging unit receives the shutter control signals and comprises an image intensifier and a driving module thereof and is used for gating and imaging a target under the control of the shutter control signals, M is more than or equal to 2, the repetition frequency of the laser pulse signals is the same but the phase difference exists, each laser driving module is connected with one laser pulse signal output end of the digital control unit, each laser diode is connected with one laser driving module, and each laser diode is driven by the corresponding laser pulse signal to output lasers.
2. The pulse phase shift based range gate imaging system of claim 1, wherein the digital control unit is configured in a high brightness imaging mode in which the laser pulse signals are sequentially out of phase by 360 °/M such that the groups of laser diodes are operated in turn, and the shutter control signal is a periodic pulse signal having a repetition frequency M times that of the single laser pulse signal.
3. The pulse phase shift based range gate imaging system of claim 1, wherein the digital control unit is configured in a multi-target imaging mode in which a phase difference of each laser pulse signal corresponds to a different imaging distance, the shutter control signal is a periodic pulse signal having a repetition frequency identical to that of the laser pulse signal, and simultaneous gate imaging of targets at a plurality of distances is achieved by adjusting a phase between the shutter control signal and each laser pulse signal.
4. The pulse phase shift based range gate imaging system of claim 1, wherein the digital control unit is configured in a full range imaging mode in which the output time interval of each laser pulse signal is controlled by a pseudo-random number sequence, the shutter control signal is a periodic pulse signal with a fixed repetition rate, and the echo signal received by the imaging unit when the shutter is opened corresponds to a target within the full range by randomizing the laser exit time.
5. The pulse phase shift based range gate imaging system of claim 1, wherein the digital control unit is configured in a brightness equalization mode based on the number of light sources, wherein a range-phase-laser diode number mapping table is built in the digital control unit, and the laser pulse signals of the corresponding phases are determined according to the target distance, and the enabling number of the laser diodes in the corresponding group is controlled to adapt to the light intensity requirements of different distances.
6. The pulse phase shift-based range gate imaging system according to claim 1, wherein the digital control unit is configured to be a duty cycle adjustment-based brightness equalization mode, wherein a range-phase-duty cycle mapping table is built in the digital control unit, and the duty cycle of the output enable signal corresponding to the laser pulse signal is adjusted according to the target distance to control the light emitting energy in unit time, thereby realizing the equalization of imaging brightness at different distances.
7. The pulse phase shift based range gate imaging system of claim 1, wherein the digital control unit is implemented by a field programmable gate array FPGA, ASIC, MCU.
8. A range-gated imaging method based on pulse phase shifting, comprising the steps of: (1) Generating M laser pulse signals with phase differences and corresponding shutter control signals, wherein M is more than or equal to 2; (2) Driving the corresponding laser diode group to output laser respectively through each laser pulse signal; (3) Combining the laser beams of each group and irradiating the target; (4) And controlling the shutter opening time of the imaging unit according to the shutter control signal, receiving the laser echo reflected by the target and imaging.
9. The pulse phase shift-based range gate imaging method as claimed in claim 8, further comprising the steps of enabling laser diodes to work in turn by enabling the phases of the laser pulse signals of each group to be different by 360/M in sequence, reducing peak light power born by the optical fibers, enabling simultaneous imaging of targets at a plurality of distances by setting phase differences of the laser pulse signals to correspond to different imaging distances and adjusting phases of the shutter control signals and the pulse signals, enabling random gate imaging within a full range of distances by controlling the emergent time of the laser pulse signals through a pseudo-random sequence, and dynamically adjusting the working number of the laser diodes or the output duty ratio of the laser pulse signals according to the target distances to achieve equalization of imaging brightness at different distances.

Description

Pulse phase shift based range gate imaging system Technical Field The invention relates to the technical field of imaging, in particular to a distance gating imaging system based on pulse phase shift. Background The distance gating camera is used as key equipment capable of realizing long-distance and anti-interference imaging, allows reflected laser of a target distance to enter imaging by precisely controlling the time difference between laser emission and shutter opening, filters ambient light and background light interference, improves imaging contrast and definition, and is widely applied to the fields of security monitoring, remote sensing detection, industrial detection, military reconnaissance and the like. The existing range gating camera mostly adopts single-path or multi-path synchronous driving laser, and realizes fixed-distance imaging by adjusting the fixed delay time of a laser illuminator and a shutter. Although the prior art has basically achieved the function of range-gated imaging, there are still a number of problems and drawbacks in practical applications. First, the optical fiber type laser illuminator has limited light output, when a plurality of laser diodes are driven to emit light to be combined into one optical fiber, if the laser power after being combined is too large and exceeds the bearing range of the optical fiber, the optical fiber can be damaged. Secondly, the imaging distance is single, and the traditional technology can only image the target at a specific distance at a time, if target information at a plurality of distances needs to be acquired, time delay needs to be adjusted repeatedly, imaging efficiency is low, and dynamic multi-target detection requirements are difficult to meet. Thirdly, the contradiction between the full-distance detection efficiency and the cost is prominent, and the mechanical scanning type full-distance detection speed is low, so that the device cannot adapt to a fast moving target. Fourth, imaging quality is unbalanced in different distances, exposure saturation is easy to occur to a close-range target due to the fact that reflected light intensity is too high, and imaging blurring is caused to a long-range target due to the fact that reflected light intensity is weak. Disclosure of Invention The invention aims to provide a distance gating imaging system based on pulse phase shift, which solves the problems of limited light output power, single imaging distance, outstanding contradiction between full-distance detection efficiency and cost, unbalanced imaging quality at different distances and the like of an optical fiber type laser illuminator in the prior art. The distance gating imaging system based on pulse phase shift comprises a digital control unit, M laser pulse signals and shutter control signals, M laser driving modules, M groups of laser diodes and an optical fiber beam combiner, wherein the digital control unit is used for generating the M laser pulse signals and the shutter control signals, the M laser driving modules, the M groups of laser diodes and the optical fiber beam combiner are used for combining laser beams output by the laser diodes of each group, the imaging unit receives the shutter control signals and comprises an image intensifier and a driving module thereof and is used for gating and imaging a target under the control of the shutter control signals, M is more than or equal to 2, the repetition frequency of the laser pulse signals is the same but the phase difference exists, each laser driving module is connected with one laser pulse signal output end of the digital control unit, each group of laser diodes is connected with one laser driving module, and each group of laser diodes outputs laser beams under the driving of the corresponding laser pulse signals. Further, the digital control unit is set in a high brightness imaging mode, wherein the phase of each laser pulse signal is sequentially different by 360 degrees/M, so that each group of laser diodes work in turn, and the shutter control signal is a periodic pulse signal, and the repetition frequency of the shutter control signal is M times that of a single laser pulse signal. Further, the digital control unit is set to a multi-target imaging mode, wherein the phase difference of each laser pulse signal corresponds to different imaging distances, the shutter control signal is a periodic pulse signal, the repetition frequency of the shutter control signal is the same as that of the laser pulse signal, and simultaneous gating imaging of targets at a plurality of distances is achieved by adjusting the phase between the shutter control signal and each laser pulse signal. Further, the digital control unit is set to a full-distance imaging mode, wherein the output time interval of each laser pulse signal is controlled by a pseudo-random number sequence, the shutter control signal is a periodic pulse signal with fixed repetition frequency, and the echo signal received