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CN-122025494-A - Time-broadening scanning framing single-line-of-sight imaging method and system

CN122025494ACN 122025494 ACN122025494 ACN 122025494ACN-122025494-A

Abstract

The invention relates to the technical field of imaging systems, and provides a time-broadening scanning framing single-line-of-sight imaging method and a system, wherein the method comprises the following steps: a photocathode for converting an incident optical signal into an electron beam and transmitting a ramp-stretching pulse; the system comprises an anode grid mesh, a long magnetic lens, a deflection scanning system, a gating micro-channel plate detector and a high-voltage pulse generator, wherein the anode grid mesh and a photocathode jointly form an accelerating electric field, the long magnetic lens is used for focusing electron beams after time widening, the deflection scanning system comprises two groups of deflection plate electrodes which are arranged in an orthogonal mode, each group of deflection plate electrodes comprises two parallel opposite plate electrodes and is used for applying a two-dimensional deflection electric field to the electron beams after time widening so that the electron beams incident at different times are separated in space, the gating micro-channel plate detector is used for gating, multiplying and imaging the electron beams after deflection separation, and the high-voltage pulse generator is used for generating cathode slope widening pulses and micro-channel plate gating pulses. The invention can better realize single multi-image single line-of-sight imaging with high space-time resolution.

Inventors

  • CAI HOUZHI
  • DENG ZHIYING
  • XIANG LIJUAN

Assignees

  • 深圳大学

Dates

Publication Date
20260512
Application Date
20260413

Claims (10)

  1. 1. A time-broadened scanning framing single line-of-sight imaging system, comprising: The photoelectric cathode is used for converting an incident optical signal into an electron beam and transmitting slope widening pulses, and the photoelectric cathode is loaded with negative direct-current bias voltage and overlapped with the slope widening pulses to generate a speed difference in an electron beam group; an anode grid net which is grounded and forms an accelerating electric field together with the photocathode; A long magnetic lens, wherein the generated uniform magnetic field acts on the cathode surface of the photoelectric electrode to the MCP imaging surface and is used for focusing the electron beam after time widening; The deflection scanning system is arranged at the rear end of the action range of the uniform magnetic field generated by the long magnetic lens and consists of two groups of deflection plate electrodes which are arranged in an orthogonal mode, and each group of deflection plate comprises two parallel opposite flat plate electrodes which are used for applying a two-dimensional deflection electric field to the electron beams after time widening so as to enable the electron beams incident at different times to be separated in space; The gate control micro-channel plate detector is arranged behind the deflection scanning system and comprises a micro-channel plate evaporated with micro-strip lines, a fluorescent screen and a CCD (charge coupled device), and is used for gating, multiplying and imaging the deflected and separated electron beams; The high-voltage pulse generator is respectively connected with the photocathode and the gating microchannel plate detector and is used for generating a cathode slope broadening pulse and a microchannel plate gating pulse; The deflection scanning system enables electron beams emitted from the same space position of the photocathode and carrying different time information to deflect to a plurality of preset space positions of an imaging surface of a gating micro-channel plate detector without distortion by regulating and controlling scanning voltage amplitude and time sequence delay loaded on each group of deflection plate electrodes, so that a plurality of images are obtained on the imaging surface of the micro-channel plate under the single-view incidence condition of an object to be measured, and the gating micro-channel plate detector sequentially gates and multiplies the electron beams reaching the different space positions through gating pulses transmitted along a microstrip line, and finally a CCD (charge coupled device) records to obtain a plurality of images.
  2. 2. The time-broadening scanning framing single line-of-sight imaging system of claim 1, wherein the deflection scanning system comprises two sets of mutually perpendicular deflectors, wherein a first set of deflectors is composed of two parallel plate electrodes arranged in a horizontal direction for generating a deflection electric field in a vertical direction, a second set of deflectors is composed of two parallel plate electrodes arranged in a vertical direction for generating a deflection electric field in a horizontal direction, and four deflection plates are identical in geometric dimension, have a plate width of 40 mm, a plate length of 20 mm, and a plate spacing of 42 mm.
  3. 3. The time-stretched scanning framing single line-of-sight imaging system of claim 2, wherein the deflection scanning system and the imaging plane of the gated microchannel plate detector are 180 mm in distance Δz, and the scanning voltage applied to the deflection plate ranges from 900V to 1000V in amplitude when a cathode is applied with a-3 kV DC bias voltage and stretched pulses with a slope of 5V/ps are superimposed.
  4. 4. A time broadening scanning framing single line of sight imaging system as defined in claim 3, wherein the deflection plates are uniformly intense electric fields, the motion track of electrons in the uniformly intense electric fields is parabolic, and the electrons are continuously deflected and drifted to the imaging surface of the microchannel plate in uniform motion after exiting from the deflection system, so that two-dimensional images carrying different time information at the same spatial position are deflected to 9 different spatial positions of the imaging surface of the gating microchannel plate detector without distortion, and 9 images are obtained on the imaging surface of the microchannel plate after the single view angle incidence system of an object to be measured is realized.
  5. 5. The time-broadening scanning framing single-line-of-sight imaging system as claimed in claim 4, wherein the time resolution of the gated microchannel plate detector is 70 ps, the deflection scanning system maintains a constant deflection voltage in each time period of 70 ps, and sequentially changes the deflection voltage in time sequence, so that the electron beam is sequentially deflected to 9 different positions in the horizontal direction and the vertical direction on the imaging plane, and nine-framing imaging is achieved.
  6. 6. The time broadening scanning framing single line-of-sight imaging system of claim 5, wherein three parallel microstrip lines are evaporated on an input surface of the gate-controlled microchannel plate, each microstrip line has a width of 12 mm, a distance between adjacent microstrip lines is 3 mm, each microstrip line consists of 400 nm copper layers and 200 nm gold layers, cu is plated on a substrate, and copper layers and gold layers with the same thickness as the input surface are evaporated on the whole output surface of the microchannel plate.
  7. 7. The system of claim 6, wherein the microchannel plate has an outer diameter of 60mm, a thickness of 0.5 mm, a channel diameter of 12 μm, a channel spacing of 14 μm, a channel bevel angle of 6 DEG, a distance between the microchannel plate and the phosphor screen of 0.5 mm, and the CCD is disposed closely to the phosphor screen.
  8. 8. The time-broadening scanning framing single-line-of-sight imaging system of claim 7, wherein the horizontal direction is 14 mm, the vertical direction is 15 mm, the diameter of each image is 12mm, and the deflection distance of the electron beam in the horizontal direction is 14 mm, and the deflection distance in the vertical direction is 15 mm, so as to match the position of the microstrip line and the transmission speed of the gate pulse.
  9. 9. The time-broadening scanning framing single-line-of-sight imaging system of claim 8, wherein the transmission speed of the gating pulse on the microstrip line is 2×10 8 m/s, the gating pulse is transmitted in time sequence along the microstrip line, the electron beam images reaching different positions on the imaging plane are sequentially gated, the gated electron beams are multiplied by the microchannel plate and bombard the fluorescent screen to form visible light images, and the ungated electron beams are absorbed by the microchannel plate.
  10. 10. A time-broadening scanning framing single line-of-sight imaging method is characterized in that the time-broadening scanning framing single line-of-sight imaging method is adopted by the time-broadening scanning framing single line-of-sight imaging system in any one of claims 1-9.

Description

Time-broadening scanning framing single-line-of-sight imaging method and system Technical Field The invention relates to the technical field of imaging systems, in particular to a time-broadening scanning framing single-line-of-sight imaging method and system. Background The ultra-fast diagnosis technology is mainly applied to basic front-edge science, large science engineering, strategic high technology and the like, such as laser inertial confinement fusion (inertial confinement fusion, ICF) research, and is used for detecting an X-ray radiation process of 1-2 ns. The X-ray framing imaging camera can obtain two-dimensional space information of ICF plasma X-ray radiation and one-dimensional time information superior to subnanoseconds, and is important two-dimensional ultrafast diagnosis equipment. The current practical X-ray framing camera adopts a pinhole imaging array to split X-rays, different frames on a micro-channel plate (microchannel plate, MCP) imaging surface correspond to measured target image information of different pinholes, the number of pinholes of the pinhole array is increased along with the increase of the number of required frames, and therefore the problem of influence on diagnosis precision caused by overlarge imaging angle difference among different pinhole visual angles is solved. In this regard, a combination of electron beam time-broadening technology, deflection scanning technology and MCP traveling wave gating imaging technology provides a time-broadening scanning framing single line-of-sight imaging system. The time-varying electric field between the cathode and the grating is utilized to generate a speed difference of electrons in the electron beam group, then the time broadening of the electron pulse is gradually realized through transmission in a drift region, and a dynamic deflection plate electrode and a gating MCP detector are arranged in a subsequent motion path of the electron beam, so that a precise time gating system is constructed, and the imaging quality and the diagnosis precision of a camera are improved. The time-broadening scanning framing single-line-of-sight imaging technology is proposed according to urgent needs of ICF research, can improve imaging quality and diagnosis precision, enables an X-ray framing imaging camera to meet engineering and precision requirements, solves the requirements of ICF research, and has important scientific significance and application value. Disclosure of Invention The invention provides a time-broadening scanning framing single-line-of-sight imaging method and a system, which can overcome certain or certain defects in the prior art. A time-broadened scanning framing single line-of-sight imaging system according to the present invention includes: The photoelectric cathode is used for converting an incident optical signal into an electron beam and transmitting slope widening pulses, and the photoelectric cathode is loaded with negative direct-current bias voltage and overlapped with the slope widening pulses to generate a speed difference in an electron beam group; an anode grid net which is grounded and forms an accelerating electric field together with the photocathode; A long magnetic lens, wherein the generated uniform magnetic field acts on the cathode surface of the photoelectric electrode to the MCP imaging surface and is used for focusing the electron beam after time widening; The deflection scanning system is arranged at the rear end of the action range of the uniform magnetic field generated by the long magnetic lens and consists of two groups of deflection plate electrodes which are arranged in an orthogonal mode, and each group of deflection plate comprises two parallel opposite flat plate electrodes which are used for applying a two-dimensional deflection electric field to the electron beams after time widening so as to enable the electron beams incident at different times to be separated in space; The gate control micro-channel plate detector is arranged behind the deflection scanning system and comprises a micro-channel plate evaporated with micro-strip lines, a fluorescent screen and a CCD (charge coupled device), and is used for gating, multiplying and imaging the deflected and separated electron beams; The high-voltage pulse generator is respectively connected with the photocathode and the gating microchannel plate detector and is used for generating a cathode slope broadening pulse and a microchannel plate gating pulse; The deflection scanning system enables electron beams emitted from the same space position of the photocathode and carrying different time information to deflect to a plurality of preset space positions of an imaging surface of a gating micro-channel plate detector without distortion by regulating and controlling scanning voltage amplitude and time sequence delay loaded on each group of deflection plate electrodes, so that a plurality of images are obtained on the imaging surface of the micro-ch