Strong terahertz light spot positioning system and method based on four-quadrant light emitting diode

Abstract

The invention discloses a strong terahertz light spot positioning system and method based on a four-quadrant light emitting diode, and belongs to the field of strong terahertz photoelectric detection. The system comprises a four-quadrant detector, a four-channel signal integration unit, a programmable logic unit, a static storage unit, a data transmission module, a power supply module and an upper computer. Due to the collision ionization effect, the four-quadrant detector generates four paths of photoelectric signals under the strong terahertz irradiation condition; the signal is collected and processed by the system through a current integration method, and then the system gives the center position of the light spot according to a four-quadrant positioning algorithm. The terahertz light spot positioning and monitoring device can be used for terahertz light spot positioning and monitoring links in occasions of strong terahertz sources, applications and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of strong terahertz photoelectric detection, and particularly relates to a strong terahertz light spot positioning system based on a four-quadrant light-emitting diode and a method thereof. BACKGROUND

[0002] Strong terahertz refers to electromagnetic waves with a wavelength between 0.03 and 3 mm and a field strength above the order of kV / cm. With the development of ultra-short and ultra-strong laser technology, the main form of the current strong terahertz source is the interaction of femtosecond laser and various substances. The pulse width of the generated terahertz pulse is in the order of picoseconds, and the single-shot energy is greater than the order of microjoules. Under the new strong field conditions, the original terahertz beam detection technology faces the risk of failure, such as nonlinear distortion after the field is too strong, interference of other frequency band electromagnetic waves and the like. Therefore, it is necessary to develop a new detection scheme. Using the strong terahertz nonlinear effect to realize the detection function is a good idea, which can effectively avoid the above problems. The pre-research carried out by Chinese invention patents with application numbers 2020101383321 and 2020101383374, etc. realizes high-performance detection by using the collision ionization effect excited by strong terahertz in a light-emitting diode (LED). On this basis, the present application further proposes a strong terahertz light spot positioning system based on a four-quadrant light-emitting diode and a method thereof, which can realize accurate positioning of the centroid of the strong terahertz light spot. SUMMARY

[0003] The present application aims to overcome the defects in the prior art, and provides a strong terahertz light spot positioning system based on a four-quadrant light-emitting diode and a method thereof, which is simple and reliable, high in precision and fast in speed.

[0004] The specific technical scheme adopted by the present application is as follows: In a first aspect, the present application provides a strong terahertz light spot positioning system based on a four-quadrant light-emitting diode, which comprises a four-quadrant detector, a four-channel signal integration unit, a programmable logic unit, a static storage unit, a data transmission module, a power module and an upper computer. The four-quadrant detector comprises a 2x2 light-emitting diode array, each light-emitting diode has a positive electrode connected to ground and a negative electrode connected to an integration channel of the four-channel signal integration unit. The four-channel signal integration unit is used for collecting signals obtained through the four-quadrant detector, and is connected to and controlled by the programmable logic unit. The programmable logic unit is also connected to the static storage unit and the data transmission module, the static storage unit is used for writing and reading the collected signal data under the control of the programmable logic unit, and the data transmission module is used for realizing communication between the programmable logic unit and the external upper computer. The power module is used for supplying power for the electric equipment.

[0005] Preferably, the four-channel signal integration unit adopts an integration chip DDC114.

[0006] Preferably, the programmable logic unit adopts a CPLD chip EPM570.

[0007] Preferably, the static storage unit adopts an SRAM chip IS61LV25616AL.

[0008] Preferably, the data transmission module adopts an RS485 module MAX13488.

[0009] Preferably, the power module comprises a 5 V analog power supply, a 4.096 V reference power supply and a 3.3 V digital power supply; the analog power supply and the reference power supply are used for supplying power for the four-channel signal integration unit, and the digital power supply is used for supplying power for the four-channel signal integration unit and the programmable logic unit.

[0010] Preferably, the host computer is equipped with a graphical user interface, which is used for realizing one or more of the following functions: configuration of serial ports, sending of information, display of data text, data visualization and saving, and background subtraction.

[0011] In a second aspect, the application provides a strong terahertz spot positioning method using the strong terahertz spot positioning system based on the four-quadrant light-emitting diode according to any one of the first aspect, and the method specifically comprises the following steps: S1: The host computer sends a configuration word instruction to the programmable logic unit through the data transmission module, and the programmable logic unit configures the four-channel signal integration unit through the pins according to the instruction; The instruction comprises integration time, capacitor gear selection and test mode function; S2: The four-channel signal integration unit starts, simultaneously integrates the four-channel detector photocurrent signals obtained through the four-quadrant detector, converts the amplified end voltage into a digital signal through analog-to-digital conversion, and sends the digital signal to the programmable logic unit through the pins in series, and the programmable logic unit stores the data in the static storage unit after receiving the data; S3: After the static storage unit caches a certain amount of data, the programmable logic unit reads the data from the static storage unit and sends the data to the data transmission module, then the data transmission module converts the digital signal of the programmable logic unit into an RS485 communication signal and sends the signal to the host computer, and the host computer performs operations including calculation and visualization after receiving the data.

[0012] Compared with the prior art, the application has the following beneficial effects: 1) The detection scheme is simple and reliable. Only four sensors are needed to achieve high-precision positioning of the centroid of the strong terahertz light spot, without the need for an image sensor; 2) The detector has a fast response speed and strong signal. It uses the collisional ionization effect of a strong terahertz electric field to achieve photoelectric detection and has good anti-interference effect. 3) This invention can be widely applied to the positioning and monitoring of various types of strong terahertz source spots, including tilted wavefront terahertz sources, laser plasma terahertz sources, etc. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of a strong terahertz spot positioning system based on a four-quadrant light-emitting diode, provided by the present invention.

[0014] Figure 2 This is a schematic diagram of a strong terahertz spot positioning system based on a four-quadrant light-emitting diode, provided as an example. Detailed Implementation

[0015] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below. Technical features in the various embodiments of the present invention can be combined accordingly without mutual conflict.

[0016] like Figure 1 As shown, this invention provides a strong terahertz spot positioning system based on four-quadrant light-emitting diodes. The system mainly includes a four-quadrant detector, a four-channel signal integration unit, a programmable logic unit (CPLD), a static RAM (SRAM), a data transmission module, a power supply module, and a host computer.

[0017] The structure and connection methods of each component will be explained in detail below.

[0018] In the system of the present invention, the four-quadrant detector mainly includes a 2×2 light-emitting diode array (LED). Each LED is grounded with its positive terminal and connected to the integration channel of the four-channel signal integration unit with its negative terminal. Under strong terahertz irradiation, it can generate four photoelectric signals.

[0019] In the system of this invention, the integration channels of the four-channel signal integration unit are connected one-to-one with the negative terminals of the four-quadrant light-emitting diodes. The four-channel signal integration unit is connected to and controlled by the programmable logic unit, and is responsible for acquiring the signals obtained by the four-quadrant detector.

[0020] As a preferred embodiment of the present invention, the four-channel signal integration unit can be an integration chip DDC114.

[0021] In the system of this invention, a programmable logic unit is connected to a static storage unit. The static storage unit can write and read the acquired signal data under the control of the programmable logic unit.

[0022] In a preferred embodiment of the present invention, the programmable logic unit may be the CPLD chip EPM570.

[0023] In a preferred embodiment of the present invention, the static storage unit may be an SRAM chip IS61LV25616AL.

[0024] In the system of this invention, the programmable logic unit is connected to the data transmission module. The data transmission module is also connected to a host computer, enabling communication between the programmable logic unit and the external host computer.

[0025] In other words, the programmable logic unit is electrically connected to the four-channel signal integration unit, the static storage unit, and the data transmission module.

[0026] In a preferred embodiment of the present invention, the data transmission module may be an RS485 module MAX13488.

[0027] In a preferred embodiment of the present invention, a graphical user interface (GUI) developed using PYQT5 code is installed in the host computer to implement one or more of the following functions: configuring the serial port, sending information, displaying data text, visualizing and saving data, and background subtraction. Of course, the specific functions can be reasonably adjusted and added or deleted as needed, and the present invention does not impose any limitations.

[0028] In the system of the present invention, the power supply module is used to supply power to the other modules.

[0029] In a preferred embodiment of the present invention, the power supply module mainly includes a 5V analog power supply, a 4.096V reference power supply, and a 3.3V digital power supply. The 5V analog power supply and the 4.096V reference power supply are used to power the four-channel signal integration unit, while the 3.3V digital power supply is used to power the four-channel signal integration unit and the programmable logic unit.

[0030] Utilizing the aforementioned strong terahertz spot localization system based on four-quadrant light-emitting diodes, this invention also provides a method for terahertz spot localization. In practical use, due to the impact ionization effect, the four-quadrant detector generates four photoelectric signals under strong terahertz irradiation. These signals are acquired and processed by the system using the current integration method, and then the system determines the center position of the spot based on the four-quadrant localization algorithm. This invention can be used for terahertz spot localization and monitoring in strong terahertz sources and applications. The specific steps of the method of this invention are as follows: S1: The host computer sends the configuration word instruction to the programmable logic unit through the data transmission module. The programmable logic unit configures the four-channel signal integration unit through the pins according to the instruction.

[0031] The instructions include information such as integration time, capacitance level selection, and test mode functions.

[0032] S2: The four-channel signal integration unit starts after receiving serial port data and is configured according to instructions. The four-channel signal integration unit then simultaneously integrates the photocurrent signals from the four quadrant detectors. The programmable logic unit controls the four-channel integration unit to perform integration amplification and analog-to-digital conversion on the quadrant detector signals. That is, the voltage at the amplification end is converted from analog to digital signal and sent serially to the programmable logic unit through pins. After receiving the data, the programmable logic unit temporarily stores it in the static memory unit.

[0033] S3: After the static storage unit has cached a certain amount of data (i.e., when the amount of temporary data reaches the set value), the programmable logic unit will read all the data in the static storage unit, encode it, and send it to the data transmission module. Subsequently, the data transmission module will convert the digital signal of the programmable logic unit into an RS485 communication signal and send it to the host computer. After receiving the data, the host computer will perform operations such as spot centroid calculation and visualization.

[0034] The above-described method of the present invention will be specifically described below based on the system of the present invention through embodiments.

[0035] Example This embodiment utilizes Figure 2 The illustrated strong terahertz spot localization system based on four-quadrant light-emitting diodes provides a method for locating strong terahertz spots, as detailed below: S1. The host computer sends a configuration word command to the slave hardware, which includes integration time, capacitance level selection, and test mode function information. The CPLD chip EPM570 configures the DDC114 through the three RANGE pins according to the command.

[0036] S2 and DDC114 are activated, simultaneously integrating and amplifying the photocurrent signals from the four detectors. These signals are then converted into digital signals and serially transmitted to the EPM570 via the DOUT and DCLK pins. The EPM570 receives the data and stores it in the SRAM chip IS61LV25616AL.

[0037] S3. After buffering a certain amount of data, the EPM570 reads the data from the IS61LV25616AL and converts it into ASCII code of the specified format before sending it to the RS485 module. The MAX13488 chip of the RS485 module converts the TTL signal of the EPM570 into an RS485 communication signal and sends it to the computer (i.e., the host computer). After receiving the data, the host computer performs spot centroid calculation and visualization operations.

[0038] In this embodiment, in step S3 above, a linear algorithm is used to calculate the centroid of the light spot. The calculation method is as follows: Let the photoelectric signals of the detector excited by the light field be I... A I B I C I D Then the normalized centroid coordinates of the light spot δ x , δ y The calculation formula is: δ x = (I A + I D - I B - I C ) / ( I A + I B + I C + I D ); δ y = (I A + I B – I C - I D ) / (I A + I B + I C +I D ) The true coordinates can be obtained by multiplying the normalized coordinates by a coefficient. The system's spot positioning accuracy can be obtained through error analysis.

[0039] The aforementioned strong terahertz spot positioning system based on four-quadrant light-emitting diodes can be used for spot positioning of strong terahertz sources such as tilted wavefront terahertz sources and laser plasma terahertz sources.

[0040] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, all technical solutions obtained through equivalent substitution or transformation fall within the protection scope of the present invention.

Claims

1. A strong terahertz spot positioning system based on four-quadrant light-emitting diodes, characterized in that, It includes a four-quadrant detector, a four-channel signal integration unit, a programmable logic unit, a static storage unit, a data transmission module, a power supply module, and a host computer; The four-quadrant detector includes a 2×2 light-emitting diode array, with each light-emitting diode having its positive terminal grounded and its negative terminal connected to the integration channel of the four-channel signal integration unit. The four-channel signal integration unit is used to collect signals obtained by the four-quadrant detector, and is connected to and controlled by the programmable logic unit. The programmable logic unit is also connected to a static storage unit and a data transmission module. The static storage unit is used to write and read the acquired signal data under the control of the programmable logic unit, and the data transmission module is used to realize the communication between the programmable logic unit and the external host computer. The power module is used to supply power to electrical equipment.

2. The strong terahertz spot positioning system based on four-quadrant light-emitting diodes according to claim 1, characterized in that, The four-channel signal integration unit uses the DDC114 integration chip.

3. The strong terahertz spot positioning system based on four-quadrant light-emitting diodes according to claim 1, characterized in that, The programmable logic unit uses the CPLD chip EPM570.

4. The strong terahertz spot positioning system based on four-quadrant light-emitting diodes according to claim 1, characterized in that, The static storage unit uses an SRAM chip IS61LV25616AL.

5. The strong terahertz spot positioning system based on four-quadrant light-emitting diodes according to claim 1, characterized in that, The data transmission module uses the RS485 module MAX13488.

6. The strong terahertz spot positioning system based on four-quadrant light-emitting diodes according to claim 1, characterized in that, The power supply module includes a 5V analog power supply, a 4.096V reference power supply, and a 3.3V digital power supply; the analog power supply and the reference power supply are used to power the four-channel signal integration unit, and the digital power supply is used to power the four-channel signal integration unit and the programmable logic unit.

7. The strong terahertz spot positioning system based on four-quadrant light-emitting diodes according to claim 1, characterized in that, The host computer is equipped with a graphical user interface, which is used to implement one or more of the following functions: configuring serial port, sending information, displaying data text, data visualization and saving, and background subtraction.

8. A method for locating a strong terahertz spot using the strong terahertz spot location system based on a four-quadrant light-emitting diode as described in any one of claims 1 to 7, characterized in that, Specifically as follows: S1: The host computer sends the configuration word instruction to the programmable logic unit through the data transmission module. The programmable logic unit configures the four-channel signal integration unit through the pin according to the instruction. The instructions include integration time, capacitance level selection, and test mode functions; S2: The four-channel signal integration unit starts up and integrates the photocurrent signals of the four detectors obtained by the four-quadrant detector. The voltage at the amplification end is converted from analog to digital signal and sent serially to the programmable logic unit through the pin. After receiving the data, the programmable logic unit stores it in the static storage unit. S3: After the static storage unit caches a certain amount of data, the programmable logic unit reads the data from the static storage unit and sends it to the data transmission module. Subsequently, the data transmission module converts the digital signal of the programmable logic unit into an RS485 communication signal and sends it to the host computer. After receiving the data, the host computer performs operations including calculation and visualization.

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