CN102307046B - Time-resolved photon counting imaging system and method - Google Patents
Time-resolved photon counting imaging system and method Download PDFInfo
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Abstract
The invention relates to a time-resolved photon counting imaging system and a time-resolved photon counting imaging method. The system comprises an optical system, a detector, an acquisition card and a computer. An imaging target is positioned at the input end of the optical system. The detector is positioned at the output end of the optical system and connected with the acquisition card. The imaging target is imaged on the input face of the detector by the optical system. The acquisition card comprises a photon arrival timing signal generation circuit, a pulse peak acquisition circuit, a starting signal generation circuit, a constant temperature crystal oscillation clock circuit, a programmable logic device, a digital signal processor, a time-digital converter chip and a communication interface circuit. By the system and the method, the problem of absence of the time-resolved photon counting imaging method in conventional photon counting methods is solved; and the system and the method have the advantages of time-resolved photon counting imaging, high time resolution, high spatial resolution and the like.
Description
Technical field
The present invention relates to low-light level imaging technical field, a kind of time-resolved photon counting imaging system particularly in low-light level imaging technical field in Photon Counting Image Acquisition Technique and method.
Background technology
The extensive use in the fields such as astronomical observation, satellite remote sensing, biomedical imaging is imaged on along with the low light level, more and more higher to the sensitivity requirement of low light level imaging detection, photon counting imaging is a kind of formation method of atomic weak signal target, there is high sensitivity, therefore photon counting imaging method can be applicable to many fields, as astronomical observation, satellite remote sensing, biomedical imaging, nuclear radiation imaging, space ultraviolet imagery etc.At present for the detector of photon counting imaging, primarily of photomultiplier (PMT), single-photon avalanche diode (SPAD), microchannel plate (MCP) etc.Wherein, photomultiplier (PMT), avalanche photodide (APD) belong to single-element detector, and therefore need optical mechaical scanning just can be embodied as picture, the real-time of imaging, time resolution, spatial discrimination are not high.Based on microchannel plate (MCP), there is face battle array structure, read by position-sensitive anode, realize photon counting imaging, there is the advantages such as signal to noise ratio is high, highly sensitive, wide dynamic range, anti-drift are good. if the position-sensitive anode detector based on microchannel plate (MCP) is primarily of cascade MCP and position-sensitive anode composition.Position-sensitive anode detector photon counting imaging method based on MCP is, when detector detects a photon, and position-sensitive anode output multi-channel electronic pulse signal.Multiplex pulse signal, through electronics read-out system, can measure the position coordinates detecting photon.Through regular hour accumulation, measure the position coordinate data of a large amount of photons, according to the photon counting of diverse location, synthesis photon counting image.Position-sensitive anode mainly contains spline shape anode (Wedge and Strip Anode), vernier anode (Vernier Anode), intersection anode (Cross Strip Anode) and Multi-anode microchannel array (MAMA) and resistive anode (Resistive anode) etc. document (FENG Bing, KANG Ke-Jun, WANG Kui-Lu, et al.Nucl.Instrum.Meth.A, 2004,535:546) report Multi-anode microchannel array (MAMA) photon counting imaging.Document (Lapington J S, Sanderson B, Worth L B C, et al.Nucl.Instr.Meth A, 2002,447:250) reports the photon counting imaging adopting vernier position-sensitive anode.Document (MIAO Zhen-hua, ZHAO Bao-sheng, ZHANG Xing-hua, et al.Chinese Physics Letters, 2008,25 (7), 2698) reports the photon counting imaging adopting WSA anode.What patent (application number: 200710018631.6 single photon counting formatters) adopted is that three electrode WSA anodes carry out photon counting imaging.But it adopts waveform digitization counting, anode output multi-channel pulse signal is carried out Full wave shape and gathers, then utilize software to carry out peakvalue's checking.Because this method will gather mass data amount hash, therefore counting rate is not high.
In the document of current report, do not relate to time-resolved photon counting.There is time-resolved photon counting imaging, due to imageable target conversion process in time can be reflected, therefore there is very important scientific research value, more field can be applied to, as fluorescence lifetime imaging, biological and medical imaging, laser radar, ultraviolet early warning, diffuse optical chromatography and single molecular fluorescence spectrum, time-resolved fluorescence are micro-.
Summary of the invention
Have time-resolved photon counting imaging method to solve in existing Photoncounting methods to lack, the present invention proposes a kind of time-resolved photon counting imaging system and method.
Technical solution of the present invention is as follows:
A kind of time-resolved photon counting imaging system, comprise optical system, detector, capture card and computer, imageable target is positioned at the input of optical system, detector is positioned at the output of optical system, detector is connected with capture card, imageable target is through the input face of optical system imaging to detector, its special character is: described capture card comprises photon and arrives timing signal generator circuit, peak value of pulse Acquisition Circuit, commencing signal produces circuit, constant-temperature crystal oscillator clock circuit (OCXO), programmable logic device (FPGA), digital signal processor (DSP), time-to-digit converter chip (TDC) and communication interface circuit,
The output of the input termination detector of described peak value of pulse collecting unit, described peak value of pulse collecting unit intercoms mutually with programmable logic device,
The output of described detector arrives timing signal generator circuit by photon and is input to programmable logic device (FPGA),
The output that described commencing signal produces circuit is connected with programmable logic device (FPGA) and time-to-digit converter chip (TDC),
The output of described constant-temperature crystal oscillator clock circuit (OCXO) is connected with programmable logic device (FPGA) and time-to-digit converter chip (TDC),
Described time-to-digit converter chip (TDC) intercoms mutually with programmable logic device (FPGA),
Described digital signal processor (DSP) intercoms mutually with programmable logic device (FPGA), and described programmable logic device (FPGA) is connected with computer by communication interface circuit.
Above-mentioned photon arrives timing signal generator circuit and comprises multiplex pulse summing circuit, peak detection circuit, Low threshold comparison circuit, high threshold comparison circuit and d type flip flop F1, described multiplex pulse summing circuit is the operational amplifier U1 connecting into summation form, the multiplex pulse signal of the input pick-up probe output of described operational amplifier U1, described operational amplifier U1 exports summing signal and is sent to peak detection circuit, Low threshold comparison circuit and high threshold comparison circuit respectively; Described peak detection circuit is made up of resistance R4, electric capacity C1 and the first comparator U2; Described Low threshold comparison circuit is made up of the first potentiometer R5 and the second comparator U3; Described high threshold comparison circuit is made up of the second potentiometer R6 and the 3rd comparator U4; Peak detection circuit exports the CLK end of d type flip flop F1 to, Low threshold comparison circuit exports the D end of d type flip flop F1 to, the Q of described d type flip flop F1 holds output photon to arrive timing signal, the Q end of described d type flip flop F1 successively by after the first not gate U6, the second not gate U7 again with the output signal of high threshold comparison circuit all by or door U5, or the RST of the output termination d type flip flop F1 of door U5 holds.
Above-mentioned peak value of pulse collecting unit comprises the peak value of pulse Acquisition Circuit of multi-channel parallel, described peak value of pulse Acquisition Circuit comprises the peak value of connecting successively and keeps chip, amplifier and A/D converter, described amplifier adopts follower mode, the output of all A/D converters holds CLK to be connected with conversion, and described peak value keeps the maintenance end of chip to be connected with bleed off end.
Above-mentioned programmable logic device (FPGA) comprises peak value and gathers control unit, position decoding unit, time measuring unit, data buffer storage unit and communication control unit;
Described peak value gathers control unit and carries out peak value synchro measure for control impuls peak value collecting unit to inputted peak value of pulse, and by the peak data transmission of measurement to position decoding unit;
Described position decoding unit is used for coordinating with digital signal processor (DSP) position coordinate data solving photon;
Described time measuring unit coordinates with time-to-digit converter chip (TDC), measures the data time of advent of photon;
Described data buffer storage unit is for the data time of advent of the position coordinate data and photon that store photon;
Described communication control unit be used for control data buffer unit by photon the time of advent data and the position coordinate data of photon be sent to computer.
Above-mentioned time measuring unit comprises counter, control logic unit and time calculating unit, photon arrives timing signal, commencing signal produces circuit commencing signal and synchronizing signal input control logic unit, clock signal, the commencing signal of constant-temperature crystal oscillator clock circuit produce the commencing signal of circuit, the control signal enter counter of control logic unit, and the output of time-to-digit converter chip (TDC), counter and control logic unit is connected with time calculating unit.
The start end of clock signal digital quantizer input time chip (TDC) of above-mentioned constant-temperature crystal oscillator clock circuit, commencing signal produces the stop1 end of commencing signal digital quantizer input time chip (TDC) of circuit, and photon arrives the stop2 end of timing signal digital quantizer input time chip (TDC).
Above-mentioned constant-temperature crystal oscillator clock circuit (OCXO) adopts MDB59P3T, and described peak value keeps chip to be PKD01 chip, and described A/D converter is AD9240 chip, and described time-to-digit converter chip (TDC) is TDC-GPX chip.
A kind of time-resolved photon counting imaging method, its special character is: comprise the following steps:
1] first by optical system by target imaging to the input face of single-photon detector, single-photon detector output multi-channel pulse signal;
2] multiplex pulse signal is amplified and shaping respectively;
3] amplify and shaping after multiplex pulse signal, for generation of photon arrival timing signal, carry out the synchronous acquisition of multiplex pulse peak value simultaneously;
Produce the method that photon arrives timing signal: the multiplex pulse signal of input is sued for peace, the pulse amplitude exported after summation is between high threshold and Low threshold, when peak value of pulse being detected, then produce and export square-wave pulse signal, rising edge represents photon due in simultaneously;
The method that multiplex pulse sync peaks gathers: peak value maintenance is carried out to the multiplex pulse signal of input, photon is utilized to arrive timing signal triggering synchronous digital to analog conversion signal, thus the multiplex pulse peak value of synchronous acquisition, and buffer memory peak-data, after having gathered, the multiplex pulse peak value that synchronous bleed off falls to keep, to carry out peak value collection to the multiplex pulse inputted next time;
4] manual triggers or software trigger or external trigger produces a commencing signal measuring-signal, and the representative of signal rising edge starts to measure the moment;
5] after commencing signal produces, photon arrives timing signal, on the one hand the multiplex pulse peak value of triggering synchronous digital to analog conversion signals collecting; On the other hand as the timing signal that photon arrives, for the time of advent of measurement of photon;
The time that measurement of photon arrives is first measure the same initial time t of all arrival photons
0, utilize counter to carry out the thick time Tn of count measurement to high frequency clock, utilize split-second precision value converter to measure time interval t that photon timing signal and clock export pulse recently
n, t
nrepresent the thin time that photon arrives.Therefore the time that photon arrives can represent with following formula:
Photon the time of advent=Tn+tn-t
0(n=1,2,3 ...)
6], after gathering out the peak value of multiplex pulse, according to the coding/decoding method of multiplex pulse peak-data and detector anode, the position coordinates of photon is solved;
7] position coordinate data of the photon that synchro measure goes out and the photon data time of advent are processed, realize time-resolved photon counting imaging;
Position coordinate data and the photon data time of advent are carried out processing method and are: according to the photon data time of advent of continuous acquisition, extract the position coordinate data of commencing signal moment to the photon of the arrival in different time at intervals, for rebuilding photon counting image, thus obtain not photon counting image in the same time.
The advantage that the present invention has:
1, have time-resolved photon counting imaging, the present invention is by recording the time of advent of photon and the position coordinates of photon continuously.The photon counting image of random time sheet can be rebuild by data processing, and then reflection imageable target process over time.
2, temporal resolution is high, the method that the measurement of photon of the present invention time of advent adopts thick time measurement and fine measurement to combine.By counting the thick time that measurement of photon arrives to high-frequency stabilization degree constant-temperature crystal oscillator clock circuit, High-precision time-to-digital converter chip TDC is adopted to carry out the thin time of measurement of photon arrival.Photon measurements of arrival time can reach the precision of tens psecs.The time resolution of photon counting imaging can reach the certainty of measurement of the photon time of advent.
3, spatial resolution is high, the present invention adopts the A/D converter chip AD9240 of peak-holding circuit chip PKD01 and 14 to form peak value Acquisition Circuit, the peak value Acquisition Circuit that Billy forms with sampling holder, can the peak value of more high-precision acquisition pulse, thus solve the position coordinates detecting photon more accurately, and then obtain more high-resolution photon counting image.
4, photon count rate is high, the present invention utilizes peak-holding circuit to be maintained by peak value of pulse, waits after detecting that photon arrives timing signal, starts A/D converter and once gathers, collection value is exactly peak value, instead of by calculating peaking after whole impulse waveform is collected.So a peak value of pulse only needs to gather once.Therefore substantially reduce data volume and calculating process, therefore there is very high counting rate.
5, integrated level is high, and the present invention adopts FPGA to realize peak value collection control, position decoding, time measurement, data buffer storage and transmission, has very high integrated level and flexibility.
6, processing speed is fast.Coordinated by FPGA and DSP and realize position decoding, FPGA control data stream and carry out simple calculations, DSP realizes floating point arithmetic, has very high processing speed.
7, applied range, the present invention proposes to have time-resolved photon counting imaging system and method, can be widely used in fluorescence lifetime imaging, biological and medical imaging, laser radar, the field such as ultraviolet early warning, diffuse optical chromatography and single molecular fluorescence spectrum, time-resolved fluorescence are micro-.
Accompanying drawing explanation
Fig. 1 is time-resolved photon counting formation method schematic diagram of the present invention;
Fig. 2 is the schematic diagram that photon of the present invention arrives timing circuit;
Fig. 3 is the sequential chart that photon of the present invention arrives timing signal for generating;
Fig. 4 is multiplex pulse peak value synchronous acquisition circuit schematic diagram of the present invention;
Fig. 5 is the sequential chart of multiplex pulse peak value synchronous acquisition of the present invention;
Fig. 6 is that commencing signal of the present invention produces circuit diagram;
Fig. 7 is constant-temperature crystal oscillator clock circuit (OCXO) of the present invention output;
Fig. 8 is the fundamental diagram that FPGA peak value of the present invention gathers control unit, position decoding unit, time measuring unit, data buffer storage and transmission;
The schematic diagram of Fig. 9 photon of the present invention continuous measurement time of advent;
The sequential chart of Figure 10 photon of the present invention continuous measurement time of advent;
Figure 11 is the time-resolved photon counting image that the present invention obtains.
Embodiment
Now time-resolved photon counting formation method of the present invention and system are described by reference to the accompanying drawings, it is that example is described that this example adopts based on MCP detector WSA position-sensitive anode detector.WSA position-sensitive anode, has 3 anodes to export W, S, Z.When detecting a photon, detector is by output three road pulse signal.
Fig. 1 is time-resolved photon counting formation method theory diagram, comprise imageable target, optical system, position-sensitive anode detector based on MCP, three road enlarge leadingly and shaping is main puts, the capture card for Time-resolved imaging of the present invention (in dotted line frame part) and computer.
Imageable target is through the input face of optical system imaging to detector, when detecting a photon, detector exports three road pulse signals, and three road pulse signals are through three road preamplifiers and shaping is main puts the accurate Gaussian pulse in Hou Cheng tri-tunnel, and the three accurate Gaussian pulses in tunnel input capture card of the present invention.Capture card of the present invention measures position coordinates and photon time of advent of photon, and is sent to computer.Computer passes through data processing.Rebuild the photon counting imaging of different time sheet.
Capture card comprises photon and arrives timing signal generator circuit, three road peak value of pulse synchronous acquisition circuits, commencing signal generation circuit, constant-temperature crystal oscillator clock circuit (OCXO), programmable logic device FPGA, digital signal processor DSP, time-to-digit converter chip TDC chip and communication interface circuit.
Fig. 2 is described photon timing signal generator circuit schematic diagram, and U1 is operational amplifier, connects into the form of homophase summation, sues for peace to the three road pulse signals that main amplifier exports.Signal after summation inputs respectively and to be connected the peak detection circuit realized, the high threshold comparison circuit realizing Low threshold comparison circuit by the first potentiometer R5 and the second comparator U3 and realized by the second potentiometer R6 and the 3rd comparator U4 with the first comparator U2 by resistance R4, electric capacity C1.D type flip flop F1 is the d type flip flop with set and clear terminal, and Low threshold compares the D end exporting input d type flip flop F1, and peakvalue's checking exports the CLK end of input d type flip flop F1.One U6 and the 2nd U7 is not gate, for holding the signal exported to postpone to d type flip flop Q.High threshold compare export and Q end inhibit signal through or door U5 after be input to d type flip flop F1 clearing RST hold.The Q end output signal of d type flip flop F1 is photon arrival timing signal.
Fig. 3 is that photon arrives the sequential chart of timing signal for generating, because the pulse that detector exports detects except single photon except representative, also comprises the pulse by a small margin caused by noise, and the significantly pulse that high energy particle and pulse pile-up cause.Photon arrives timing signal for generating method, when the pulse amplitude of the signal output after summation is between high threshold and Low threshold, then the Q end of d type flip flop F1 exports square-wave pulse signal, this square-wave pulse signal is that photon arrives timing signal, representative detects a photon, when the pulse amplitude that the signal after suing for peace exports is less than Low threshold or is greater than high threshold, then not output photon time timing signal.
Fig. 4 is the circuit theory diagrams of peak value of pulse collecting unit, and each road comprises peak value and keeps chip, passes through the follower and high-precision a/d converter that are connected into by amplifier.Peak value keeps chip to adopt the PKD01 chip of ADI company, and A/D converter adopts the AD9240 chip of ADI company.Three road peak values keep 1 pin of chip and 14 pins to connect together as the input of the synchronous bleed off signal of peak value, and the CLK that three road A/D convert chip AD9240 connects together as the synchronous figure signal of A/D.
The synchronous acquisition sequential chart of Tu5Wei tri-road peak value of pulse.After three road pulse signals enter into peak value maintenance 0-2, peak-holding circuit maintains the peak value of pulse, and meanwhile, three road pulse signal input photons arrive timing signal generator circuit, if the peak value of pulse after summation is between Low threshold and high threshold, photon will be produced and arrive timing signal.Then when the FPGA on capture card detects that photon arrives timing signal, FPGA exports the synchronous figure signal of A/D and drives three A/D converters to gather the peak value of three peak-holding circuits maintenances, after having gathered, FPGA exports the synchronous bleed off signal of peak value, make three synchronous bleed off peak values of peak-holding circuit, to keep the peak value of three road input pulses next time.At the 4th rising edge of the synchronous figure signal of A/D, three A/D converters export three road peak value of pulse data to FPGA.
Fig. 6 is that commencing signal produces circuit, exports and become high level signal from low level after pressing the button S.Signal rising edge represents start time, and commencing signal is input to FPGA and is input to the stop1 end of TDC chip.
Fig. 7 constant-temperature crystal oscillator clock circuit (OCXO) adopts the MDB59P3T of MMDC-TECH company of the U.S., and the clock that constant-temperature crystal oscillator clock circuit (OCXO) produces high frequency stability is input to FPGA and is input to the start end of TDC chip.
Fig. 8 is the structural representation of programmable logic device (FPGA), comprise peak value and gather control unit, position decoding unit, time measuring unit, data buffer storage unit and communication control unit, the peak value of pulse that peak value collection control unit inputs for paired pulses peak value Acquisition Circuit is measured, and by the peak data transmission of measurement to position decoding unit; Position decoding unit is used for coordinating with digital signal processor (DSP) position coordinate data solving photon, time measuring unit coordinates with time-to-digit converter chip (TDC), measure the data time of advent of photon, described data buffer storage unit is for the data time of advent of the position coordinate data and photon that store photon; Described communication control unit be used for control data buffer unit by photon the time of advent data and the position coordinate data of photon be sent to computer.After commencing signal, when photon arrive timing signal arrive time, peak value gather the peak value of three tunnel pulses of control realization to input and measure.The three tunnel peak-data input position decoding units measured, position decoding module coordinates the position coordinates solving photon with DSP.DSP and FPGA is connected, and with FPGA cooperating, according to the multiplex pulse peak-data gathered, solve the position coordinates of photon, the method for the calculating photon position of WSA position-sensitive anode is:
X＝(2×Q1)/(Q1+Q2+Q3) Y＝(2×Q2)/(Q1+Q2+Q3)
Time measuring unit coordinates with time-to-digit converter chip, measures the time of advent of photon, and position coordinate data and the photon data time of advent of photon deposit data buffer storage unit FIFO in a synchronous manner.Data in data buffer storage unit FIFO, under the control of communication control unit, by USB20.0 interface circuit, are sent to computer.
FPGA control data stream and carry out simple calculations, DSP realizes complex calculation, as division and floating point arithmetic.
Fig. 9 is the schematic diagram of the photon continuous measurement time of advent, for FPGA realizes time measurement module in dotted line wire frame.Time measurement module comprises counter, control logic and time calculating unit.Time measurement module coordinates with time-to-digit converter chip (TDC), measures the time of advent of photon.The start end of the clock signal input TDC chip of OCXO, the stop1 end in commencing signal input TDC, photon arrives the stop2 end in timing signal input TDC.
The sequential of Figure 10 photon continuous measurement time of advent.The method that the measurement of photon time of advent adopts thick time measurement and fine measurement to combine.Manual triggers produces after commencing signal, and the rising edge of commencing signal resets counter, and the stop1 channel measurement of TDC goes out the time interval t that commencing signal rising edge and OCXO export pulse
0, under the control of the controller, the t that " 0 " that meter computing aid exports and TDC export
0, the moment when unification representing all photons time of advent rises.
When after commencing signal, counter counts the clock that constant-temperature crystal oscillator clock circuit OCXO exports, when a photon arrives timing signal arrival, the stop2 channel measurement of TDC goes out the time interval t that photon timing signal rising edge and constant-temperature crystal oscillator clock circuit (OCXO) export pulse recently, and t represents the thin time of photon arrival.Count value T in this hour counter represents the thick time that photon arrives.Therefore the time that photon arrives can represent with following formula
Photon the time of advent=Tn+tn-t
0(n=1,2,3 ...)
Time Calculation module calculates the time of photon arrival according to above formula.Under the control of control logic, the time that photon arrives is deposited data buffer storage unit FIFO.
Position coordinate data and the photon data time of advent of photon deposit FIFO buffer memory in a synchronous manner.Data in FIFO buffer memory, under the control of usb communication control module, by USB20.0 interface circuit, are sent to computer.Develop computer software processes the position coordinate data of photon and the photon data time of advent, And Methods of Computer Date Processing is, according to the photon data time of advent of continuous acquisition, the position coordinate data from commencing signal to the photon of the arrival in any time at intervals can be found, rebuild photon counting image, thus obtain not photon counting image in the same time, realize time-resolved photon counting imaging.Time resolution can arrive the certainty of measurement of the photon time of advent.
Time-to-digit converter chip (TDC) is the TDC-GPX chip of German ACAM company, TDC-GPX chip precision can reach 10ps, therefore use method of the present invention, time-resolved photon counting imaging can reach the temporal resolution of 10 psecs.
Figure 11 is the time-resolved photon counting image adopting capture card of the present invention to obtain, and imageable target is the not photon counting imaging figure in the same time of resolving power test target.
The method that employing native system is corresponding is:
1] first by optical system by target imaging to the input face of single-photon detector, single-photon detector output multi-channel pulse signal;
2] multiplex pulse signal is amplified and shaping respectively;
3] amplify and shaping after multiplex pulse signal, for generation of photon arrival timing signal, carry out the synchronous acquisition of multiplex pulse peak value simultaneously;
Produce the method that photon arrives timing signal: the multiplex pulse signal of input is sued for peace, the pulse amplitude exported after summation is between high threshold and Low threshold, when peak value of pulse being detected, then produce and export square-wave pulse signal, rising edge represents photon due in simultaneously;
The method that multiplex pulse sync peaks gathers: peak value maintenance is carried out to the multiplex pulse signal of input, photon is utilized to arrive timing signal triggering synchronous digital to analog conversion signal, thus the multiplex pulse peak value of synchronous acquisition, and buffer memory peak-data, after having gathered, the multiplex pulse peak value that synchronous bleed off falls to keep, to carry out peak value collection to the multiplex pulse inputted next time;
4] manual triggers or software trigger or external trigger produces a commencing signal measuring-signal, and the representative of signal rising edge starts to measure the moment;
5] after commencing signal produces, photon arrives timing signal, on the one hand the multiplex pulse peak value of triggering synchronous digital to analog conversion signals collecting; On the other hand as the timing signal that photon arrives, for the time of advent of measurement of photon;
The time that measurement of photon arrives is first measure the same initial time t of all arrival photons
0, utilize counter to carry out the thick time Tn of count measurement to high frequency clock, utilize split-second precision value converter to measure time interval t that photon timing signal and clock export pulse recently
n, t
nrepresent the thin time that photon arrives.Therefore the time that photon arrives can represent with following formula:
Photon the time of advent=Tn+tn-t
0(n=1,2,3 ...)
6], after gathering out the peak value of multiplex pulse, according to the coding/decoding method of multiplex pulse peak-data and detector anode, the position coordinates of photon is solved;
7] position coordinate data of the photon that synchro measure goes out and the photon data time of advent are processed, realize time-resolved photon counting imaging;
Position coordinate data and the photon data time of advent are carried out processing method and are: according to the photon data time of advent of continuous acquisition, extract the position coordinate data of commencing signal moment to the photon of the arrival in different time at intervals, for rebuilding photon counting image, thus obtain not photon counting image in the same time.
It is that example is described that this example adopts based on MCP detector WSA position-sensitive anode detector, WSA anode has three tunnels to export, therefore example capture card of the present invention be input as three tunnels, capture card Nei You tri-road peak value of pulse Acquisition Circuit, input pulse summation in You Dui tri-road produces the circuit of timing signal.Can not assert that the specific embodiment of the present invention is only limitted to the MCP detector of WSA anode position-sensitive anode reading.If the position-sensitive anode of detector is vernier anode, then capture card be input as nine tunnels, capture card Nei You nine road peak value of pulse Acquisition Circuit, the input pulse summation of You Dui nine road produces the circuit of timing signal, position-sensitive anode is resistive anode, capture card be input as four tunnels, capture card Nei You tetra-road peak value of pulse Acquisition Circuit, input pulse summation in You Dui tetra-road produces the circuit of timing signal.Without departing from the inventive concept of the premise, carry out some simple deductions and conversion, all should be considered as scope.
Claims (7)
1. a time-resolved photon counting imaging system, comprise optical system, single-photon detector, capture card and computer, imageable target is positioned at the input of optical system, single-photon detector is positioned at the output of optical system, single-photon detector is connected with capture card, imageable target is through the input face of optical system imaging to single-photon detector, it is characterized in that: described capture card comprises photon and arrives timing signal generator circuit, peak value of pulse collecting unit, commencing signal produces circuit, constant-temperature crystal oscillator OCXO clock circuit, programmable logic device FPGA, digital signal processor DSP, time-to-digit converter TDC chip and communication interface circuit,
The output of the input order photon detector of described peak value of pulse collecting unit, described peak value of pulse collecting unit intercoms with programmable logic device FPGA phase,
The output of described single-photon detector arrives timing signal generator circuit by photon and is input to programmable logic device FPGA,
The output that described commencing signal produces circuit is all connected with programmable logic device FPGA and time-to-digit converter TDC chip,
The output of described constant-temperature crystal oscillator OCXO clock circuit is all connected with programmable logic device FPGA and time-to-digit converter TDC chip,
Described time-to-digit converter TDC chip intercoms with programmable logic device FPGA phase,
Described digital signal processor DSP intercoms with programmable logic device FPGA phase, and described programmable logic device FPGA is connected with computer by communication interface circuit.
2. time-resolved photon counting imaging system according to claim 1, it is characterized in that: described photon arrives timing signal generator circuit and comprises multiplex pulse summing circuit, peak detection circuit, Low threshold comparison circuit, high threshold comparison circuit and d type flip flop (F1), described multiplex pulse summing circuit is the operational amplifier (U1) connecting into summation form, the input of described operational amplifier (U1) receives the multiplex pulse signal of single-photon detector output, described operational amplifier (U1) exports summing signal and is sent to peak detection circuit respectively, Low threshold comparison circuit and high threshold comparison circuit, described peak detection circuit is made up of resistance (R4), electric capacity (C1) and the first comparator (U2), described Low threshold comparison circuit is made up of the first potentiometer (R5) and the second comparator (U3), described high threshold comparison circuit is made up of the second potentiometer (R6) and the 3rd comparator (U4), peak detection circuit exports the CLK end of d type flip flop (F1) to, Low threshold comparison circuit exports the D end of d type flip flop (F1) to, the photon that the Q end of described d type flip flop (F1) exports arrive timing signal successively by the first not gate (U6), after the second not gate (U7) again with the output signal of high threshold comparison circuit all by or door (U5), or the RST of the output termination d type flip flop (F1) of door (U5) holds.
3. time-resolved photon counting imaging system according to claim 1 and 2, it is characterized in that: described peak value of pulse collecting unit comprises the peak value of pulse Acquisition Circuit of multi-channel parallel, described peak value of pulse Acquisition Circuit comprises the peak value of connecting successively and keeps chip, amplifier and A/D converter, described amplifier adopts follower mode, the output of all A/D converters holds CLK to be connected with conversion, and described peak value keeps the maintenance end of chip to be connected with bleed off end.
4. time-resolved photon counting imaging system according to claim 3, is characterized in that: described programmable logic device FPGA comprises peak value and gathers control unit, position decoding unit, time measuring unit, data buffer storage unit and communication control unit;
Described peak value gathers control unit and carries out peak value synchro measure for control impuls peak value collecting unit to inputted peak value of pulse, and by the peak data transmission of measurement to position decoding unit;
Described position decoding unit is used for coordinating the position coordinate data solving photon with digital signal processor DSP;
Described time measuring unit coordinates with time-to-digit converter TDC chip, measures the data time of advent of photon;
Described data buffer storage unit is for the data time of advent of the position coordinate data and photon that store photon;
Described communication control unit be used for control data buffer unit by photon the time of advent data and the position coordinate data of photon be sent to computer.
5. time-resolved photon counting imaging system according to claim 4, it is characterized in that: described time measuring unit comprises counter, control logic unit and time calculating unit, photon arrives timing signal, commencing signal produces commencing signal and the synchronizing signal input control logic unit of circuit, the clock signal of constant-temperature crystal oscillator clock circuit, commencing signal produces the commencing signal of circuit, the control signal enter counter of control logic unit, time-to-digit converter TDC chip, the output of counter and control logic unit is connected with time calculating unit.
6. time-resolved photon counting imaging system according to claim 5, it is characterized in that: the start end of the clock signal digital quantizer input time TDC chip of described constant-temperature crystal oscillator OCXO clock circuit, commencing signal produces the stop1 end of the commencing signal digital quantizer input time TDC chip of circuit, and photon arrives the stop2 end of timing signal digital quantizer input time TDC chip.
7. time-resolved photon counting imaging system according to claim 6, is characterized in that: described peak value keeps chip to be PKD01 chip, and described A/D converter is AD9240 chip, and described time-to-digit converter TDC chip is TDC-GPX chip.
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| CN106443757B (en) * | 2016-09-23 | 2018-12-07 | 沈阳东软医疗系统有限公司 | A kind of device and detector obtaining annihilation event time of origin |
| US10162066B2 (en) * | 2017-02-06 | 2018-12-25 | General Electric Company | Coincidence-enabling photon-counting detector |
| CN107290635B (en) * | 2017-07-19 | 2019-08-02 | 中国科学院长春光学精密机械与物理研究所 | Signal processing structure and method applied to UV corona detection device |
| CN107462898B (en) * | 2017-08-08 | 2019-06-28 | 中国科学院西安光学精密机械研究所 | Based on the gate type diffusing reflection of monochromatic light subarray around angle imaging system and method |
| CN108471303B (en) * | 2018-03-29 | 2021-06-25 | 中国人民解放军国防科技大学 | Programmable nanosecond timing precision pulse generator based on FPGA |
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| CN108955906B (en) * | 2018-06-27 | 2020-05-19 | 南京邮电大学 | Time-analog conversion circuit applied to single photon detector |
| CN110161552B (en) * | 2019-04-28 | 2021-03-05 | 东软医疗系统股份有限公司 | Data processing method, device and equipment for detector |
| CN111721411B (en) * | 2020-06-30 | 2021-06-04 | 北京工业大学 | Signal processing circuit for high-space-time resolution photon counting imaging |
| CN112197879B (en) * | 2020-09-14 | 2021-10-12 | 中国科学院西安光学精密机械研究所 | High-time-resolution single photon detection method and single photon detection system |
| CN112946688B (en) * | 2021-02-02 | 2024-02-02 | 松山湖材料实验室 | Novel photon counting laser radar 3D imaging method and device |
| CN113099209A (en) * | 2021-03-24 | 2021-07-09 | 清华大学 | Non-visual field imaging device and method based on photomultiplier tube array |
| CN114637464B (en) * | 2022-02-24 | 2024-05-14 | 中国大唐集团科学技术研究院有限公司西北电力试验研究院 | Flexibly-controlled ten-clock staged timing and data storage method |
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