CN104317214A - Ultraviolet photon counting detector with position readout circuit - Google Patents

Abstract

The invention relates to an ultraviolet photon counting detector with a position readout circuit. The ultraviolet photon counting detector includes a multi-path pulse acquisition and position readout circuit system; and the multi-path pulse acquisition and position readout circuit system includes a charge sensitivity amplification module, a filtering and shaping module and a peak value holding module of an analog circuit part as well as an analog-to-digital version module, a USB data read-write module and a software imaging system of a digital circuit part. The ultraviolet photon counting detector with the position readout circuit of the invention has the advantages of simple structure, small size, portable convenience, convenient operation and high spatial resolution, and can meet the application requirements of deep space exploration and ultraviolet optical spectrum instruments.

Description

A UV Photon Counting Detector with Position Readout Circuit

technical field

The invention belongs to the technical field of ultraviolet detection, and relates to an ultraviolet photon counting detector with a position readout circuit, which is an ultraviolet photon counting detector.

Background technique

At present, two-dimensional position-sensitive photon counting imaging detectors in the ultraviolet band using microchannel plates (MCPs) have been widely used in fields such as space astronomy, deep space exploration, and photoelectric countermeasures. The photon counting imaging detector works in the range of 10nm to 280nm, and is used to detect and image the weak radiation signal of the earth's plasma layer. Common position sensitive anodes include wedge strip (WSA) anode, delay line anode (XDL) and Vernier anode. Among them, the resolution of the UV photon counting detector based on the Vernier anode can reach several microns, and the counting rate is as high as hundreds of kcps, which has important application prospects in the field of UV detection.

Regarding the method of collecting and imaging the analog signal at the front end of the ultraviolet detector, a data acquisition card based on a PCI interface is generally used at present, together with relevant data processing and imaging control software. The traditional PCI bus interface data acquisition card can transmit 32-bit or 64-bit data at a time, and the data transmission rate can reach up to 1GB/s. In the early stage of the development of the ultraviolet detector, it is widely used for testing and testing the performance of the detector. But its cost is relatively high, and bulky. When the development of spacecraft equipment reaches a relatively mature stage, how to make the equipment smaller and reduce the cost is an important consideration.

Contents of the invention

The present invention solves the technical problems in the prior art, and provides an ultraviolet photon counting method with a position readout circuit to determine the actual position of the input photon by collecting and processing the charge signal, reducing the size of the detector and reducing the cost. detector.

In order to solve the problems of the technologies described above, the technical solution of the present invention is specifically as follows:

An ultraviolet photon counting detector with position readout circuitry, comprising:

Multi-channel pulse acquisition and position readout circuit system, including: charge sensitive amplification module, filter shaping module, peak hold module of analog circuit part, analog-to-digital conversion module of digital circuit part, USB data reading and writing module, software imaging system;

The charge-sensitive amplification module includes multiple charge-sensitive amplifiers, which are respectively used to receive the induced charge output by each electrode of the anode of the ultraviolet detector and convert it into a voltage signal; obtain a high-impedance, low-noise signal for subsequent circuit processing and collection;

The filter shaping module is used to adjust the waveform of the voltage signal converted from the front-end charge and improve the signal-to-noise ratio to form a pulse that approximates a Gaussian waveform;

The peak hold module is used to widen the peak value of the pulse signal of the quasi-Gaussian waveform to improve the sampling accuracy of the subsequent A/D sampling circuit;

The analog-to-digital conversion module is used to accurately sample the pulse signal output by the analog circuit of the ultraviolet detector. After the sampling is completed, the collected analog signal is quantized and converted into a digital signal with 12-bit precision;

The USB data read-write module transmits data via USB, and continuously sends the collected pulse semaphore to the computer in real time, and stores it in the computer hard disk in hexadecimal form;

The software decoding imaging module is used to restore the analog value of the digital signal received by the computer, and convert the analog value of each pulse into the two-dimensional position coordinates of the photon according to the decoding formula of the detector anode, and finally display it on the software An image of the position of individual photons.

In the above technical solution, the charge-sensitive amplification module includes 9 charge-sensitive amplifiers.

In the above technical solution, a data transmission speed matching module is also provided for matching the data transmission speed.

The present invention has following beneficial effect:

The ultraviolet photon counting detector with a position readout circuit of the present invention can realize high-speed and accurate collection of the charge pulse signal output from the anode rear end of the ultraviolet photon counting detector, 12-bit precise analog-to-digital conversion, fast data transmission, and computational imaging and other functions.

The invention has the advantages of simple circuit structure, small size, easy to carry, convenient operation, high spatial resolution of the detector, and meets the application requirements of deep space detection and ultraviolet spectrum instruments.

Description of drawings

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments.

Figure 1 is a schematic diagram of the functional modules of the photon counting detector position readout circuit.

Figure 2 is a workflow diagram of the imaging software.

Detailed ways

Invention idea of the present invention is:

The ultraviolet photon counting detector with position readout circuit of the present invention comprises:

Multi-channel pulse acquisition and position readout circuit system, including the charge sensitive amplification module, filter shaping module, peak hold module of the analog circuit part, and the analog-to-digital conversion (A/D) module, data transmission speed matching module of the digital circuit part, USB data reading and writing module, software decoding calculation module, software imaging module.

There are 9 charge-sensitive amplifiers, which are respectively used to receive the induced charge output by each electrode of the anode of the ultraviolet detector and convert it into a voltage signal. Obtain a high-impedance, low-noise signal for processing and collection by subsequent circuits.

The filter shaping module is used to adjust the waveform of the voltage signal converted from the front-end charge and improve the signal-to-noise ratio to form a pulse that approximates a Gaussian waveform.

The peak hold module is used to widen the peak value of the pulse signal of the quasi-Gaussian waveform to improve the sampling accuracy of the subsequent A/D sampling circuit.

The analog-to-digital conversion module is used to accurately sample the pulse signal output by the analog circuit of the ultraviolet detector. After the sampling is completed, the collected analog signal is quantized and converted into a digital signal with 12-bit precision.

The USB data read-write module transmits data through USB, and sends the collected pulse semaphores to the computer continuously in real time, and stores them in the hard disk of the computer in the form of hexadecimal. This transmission method has the characteristics of fast speed, large amount of data, and convenient use, which meets the needs of carrying and using the detector in various occasions.

The software decoding imaging module is used to restore and calculate the analog value of the digital signal received by the computer, and convert the analog value of each pulse into the two-dimensional position coordinates of the photon according to the decoding formula of the detector anode, and finally display it on the software An image of the position of each photon.

Below in conjunction with the embodiment that accompanying drawing 1 provides, the present invention is described in further detail.

Referring to Fig. 1, a position readout circuit of an ultraviolet photon counting detector includes three parts: an analog signal processing circuit, a digital acquisition circuit system and an upper computer control software.

The analog circuit described in this embodiment includes several modules of charge sensitive amplification, filter shaping and peak hold. Its working principle is: when ultraviolet photons are incident into the detector, each electrode of the anode of the detector collects a certain amount of charge. The charge preamplification module of the analog circuit converts the received charge signal into a voltage signal. The signals output by the preamplifier are summed and then sent to a fast shaping and amplifying module. The present invention uses the best shaping and amplifying device on the market to obtain a pulse signal with a width of 500ns and an approximate Gaussian waveform. In order to extend the holding time of the highest peak of the pulse and make the subsequent acquisition circuit accurately sample, a peak hold module is added, and a pulse with a peak width of about 2 μs is obtained by using a dedicated peak hold module processor. Add up the results of the nine channels, and generate a TTL pulse with a pulse width of tens of nanoseconds through the window comparator, which is used to trigger accurate sampling of the subsequent digital circuit part.

The digital circuit module described in this embodiment includes an analog-to-digital (A/D) conversion control module, a data cache module, and a USB read-write control module. The analog input end of the A/D conversion device, the A/D device used is ADS-1202ME of DETEL Company of the United States, with a sampling rate of 2MHz and a conversion accuracy of 12bit. Under the trigger of TTL synchronous signal, FPGA controls A/D device to receive and convert analog data, and store the obtained digital signal in asynchronous FIFO. The function of asynchronous FIFO is to match the sampling speed of A/D and the data transmission speed of back-end USB.

The USB transmission unit adopts the CY7C68013A chip of Cypress Company, with a maximum clock frequency of 48MHz. The USB chip transmits data in SLAVE FIFO mode under the control of FPGA, and every 1KB of data written inside is automatically packaged and sent to the computer.

The USB transmission chip used can only be set to transmit 8-bit data or 16-bit data at a time, and the FPGA expands the obtained 12-bit digital quantity to 16-bit digital quantity through serial-to-parallel conversion and transmits it to the computer.

The software decoding imaging module is used to restore the analog quantity of the collected digital signal, calculate the actual position of the incident ultraviolet photon according to the anode decoding formula, and draw and image the work. The specific process is shown in Figure 2. The photon position decoding formula of the Vernier anode is as follows:

Assuming that the charge amounts of the nine circuits are θ ₁ , θ ₂ , θ ₃ ... θ ₉ , according to the structural characteristics of the Vernier anode, the following derivation can be made:

${\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; arctan</span>}<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}}{\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>$

${\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; arctan</span>}<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; 5</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; 6</span>}}}{\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; 5</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; 6</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>$

${\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; arctan</span>}<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; 7</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; 8</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; 9</span>}}}{\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; 8</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; 9</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>$

Introduce parameters θ _x ,θ _y ,m _x ,m _y , which are defined as:

θ _x =rem(θ _A +θ _B ,2π),θ _y =rem(θ _c +θ _B ,2π),

m _x ＝fix[(θ _A +θ _B )/2π],m _y ＝fix[(θ _c +θ _B )/2π]

Among them, rem() means rounding, and fix() means rounding. Then the photon position coordinates can be expressed as:

$\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; \&lambda;</span>}\frac{{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}\mathrm{<span\; class="notranslate">\; \&lambda;</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; Y</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; \&lambda;</span>}\frac{{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}}\mathrm{<span\; class="notranslate">\; \&lambda;</span>}$

Here the coefficient λ=5.346mm.

The invention has the advantages of simple circuit structure, small size, easy to carry, convenient operation, high spatial resolution of the detector, and meets the application requirements of deep space detection and ultraviolet spectrum instruments.

This embodiment is just an example for the Vernier anode detector. Obviously, different deformations can be made according to the design idea of the present invention, and the position readout circuit system of the ultraviolet detector with different anodes can be derived, and is not limited by the disclosed embodiment. , these deformations are all within the protection scope of the present invention.

Apparently, the above-mentioned embodiments are only examples for clear description, rather than limiting the implementation. For those of ordinary skill in the art, other changes or changes in different forms can be made on the basis of the above description. It is not necessary and impossible to exhaustively list all the implementation manners here. And the obvious changes or changes derived therefrom are still within the scope of protection of the present invention.

Claims (3)

1., with a ultraviolet photon digital detector for position sensing circuit, it is characterized in that, comprising:

Multiplex pulse gathers and position sensing circuit system, comprising: the Charge sensitive amplifier module of artificial circuit part, filter shape module, peak value hold module, and the analog-to-digital conversion module of digital circuits section, usb data module for reading and writing, software image system;

Charge sensitive amplifier module comprises multiple charge amplifiers, is respectively used to the induced charge receiving the output of each electrode of ultraviolet detector anode, is converted into voltage signal; Obtain the signal of a high impedance, low noise, deal with for follow-up circuit and collect;

The voltage signal that filter shape module is used for coming front end charge conversion carries out waveform adjustment and improves Signal-to-Noise, forms the pulse of an approximate Gaussian waveform;

Peak value hold module is used for the peak value broadening of the pulse signal of accurate Gaussian waveform, improves the sampling accuracy of follow-up A/D sample circuit;

The pulse signal that analog-to-digital conversion module is used for ultraviolet detector mimic channel exports accurately is sampled, and sampling terminates the rear simulating signal quantification treatment to adopting, and is converted to the digital signal of 12 precision;

Usb data module for reading and writing is the mode transmitting data with USB, the pulse signal amount of adopting constantly is sent to computing machine in real time, stores with 16 binary form in hard disc of computer;

Software decode image-forming module is used for making analog quantity restore calculation to the digital signal that computing machine receives, and according to the decoding formula of detector anode, the analog value of each pulse is converted to the two-dimensional position coordinate of photon, on software, finally demonstrates the location drawing picture of each photon.

2. the ultraviolet photon digital detector with position sensing circuit according to claim 1, is characterized in that, described Charge sensitive amplifier module comprises 9 charge amplifiers.

3. the ultraviolet photon digital detector with position sensing circuit according to claim 1, is characterized in that, be also provided with data rate matching module, for mating data rate.