Integrated detection device of liquid terahertz radiation system

Abstract

The application relates to an integrated detection device of a liquid terahertz radiation system and belongs to the technical field of terahertz detection. The application comprises a laser focusing module, a liquid circulation module and a multi-dimensional detection module, wherein the laser focusing module generates high-intensity and stable laser required by experiments and acts on a liquid medium to excite terahertz waves; the liquid circulation module is used for generating a liquid shape, size, state and the like required in the liquid terahertz radiation system, can optimize the size of the medium required by experiments, and improves the excitation efficiency of terahertz; the multi-dimensional detection module is used for detecting the terahertz waves excited by the laser focusing liquid medium, and a coherent detection method with simple structure and easy operation is used for detecting the terahertz waves in space, so that the terahertz waves in space can be directly detected without needing to be enhanced first. The application is small and integrated, low in cost, high in maintainability and expansibility, and is favorable for finding the strongest terahertz distribution area in space.

Description

Technical Field

[0001] This invention relates to an integrated detection device for a liquid terahertz radiation system, belonging to the field of terahertz detection technology. Background Technology

[0002] Terahertz radiation is a novel radiation source with many unique advantages. Its unique advantages in terms of transparency, safety, strong spectral resolution, and low energy make it widely applicable in fields such as transparent imaging of opaque objects, non-destructive testing, biomedical diagnostics, object phase identification, and object morphology identification. To achieve efficient utilization of terahertz radiation, it is first necessary to find a high-quality and efficient terahertz radiation source. Among many terahertz radiation sources, liquid terahertz radiation sources have been extensively studied due to their good self-healing properties, high molecular density, and low ionization energy. However, the radiation mechanism and radiation mode of liquid terahertz radiation sources still need further investigation. Although microwave anechoic chambers can be used in the process of elucidating terahertz radiation modes, current terahertz radiation systems are... The sheer size of liquid terahertz sources makes them impractical to relocate to a microwave anechoic chamber, which is also prohibitively expensive. Furthermore, there are few integrated multi-dimensional detection devices for probing liquid terahertz radiation sources. After terahertz waves are emitted, efficiently and accurately determining their intensity and spatial distribution is a pressing issue. Terahertz waves are a type of electromagnetic wave, representing matter with a high-dimensional spatial distribution. In 2021, Chen Yuxuan et al. proposed detecting the strongest terahertz waves in transverse emission from a liquid terahertz radiation source. Therefore, in the process of efficiently detecting high-quality terahertz radiation, a convenient and accurate integrated multi-dimensional detection method plays a crucial role in determining the spatial and intensity distribution of terahertz waves. Currently, in-depth research on the multi-dimensional spatial detection of liquid terahertz radiation sources is lacking, necessitating further improvements in the detection dimensions of terahertz waves.

[0003] Existing research indicates that the terahertz excitation process is affected by the medium-related nonlinear response and refractive index. Terahertz is not emitted from only one direction, but the multidimensional distribution of terahertz should be considered. However, current detection methods for liquid terahertz radiation sources are relatively simple, only measuring displacement or angle, which limits our understanding of the spatial distribution of terahertz.

[0004] Currently, most devices used for terahertz detection can only detect terahertz in one direction. For example, in Yu Bing's paper on terahertz divergence angle measurement technology, the device only detects the angular direction of terahertz radiation; the device described in patent 202210892578.7 does not measure other dimensional directions of terahertz, and a bias electric field is added during the detection process to enhance the first terahertz wave before detection. It cannot comprehensively and effectively detect the spatial distribution of terahertz. This device can directly detect the first terahertz wave without adding a bias electric field and find the strongest first terahertz wave in space. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide an integrated detection device for liquid terahertz radiation system, which solves the problem of the current single detection angle and dimension of liquid terahertz radiation system. It is a simple device with simple structure, convenient operation, low cost and easy implementation to detect the distribution of the strongest terahertz wave first excited in space by liquid terahertz radiation system.

[0006] The technical solution of the present invention is: an integrated detection device for a liquid terahertz radiation system, comprising: a laser focusing module, a liquid circulation module, and a multi-dimensional detection module.

[0007] The laser focusing module is used to generate a laser beam with a center wavelength of 800nm, relatively high energy and relatively stable performance. Through a focusing lens with a focal length of 60μm, the laser can be precisely focused on the liquid medium, so that the laser can generate optimal interaction with the liquid medium, thereby radiating stronger terahertz waves.

[0008] The liquid circulation module is used to generate the liquid shape, size, and state required in the liquid terahertz radiation system. It can generate water lines, water films, water droplets, and other shapes, and the temperature and pressure are adjustable. It can generate water lines with diameters from 150μm to 320μm. Because a large amount of water has a strong absorption effect on terahertz waves, theoretically, smaller diameter water lines can generate stronger terahertz waves in experiments.

[0009] The multi-dimensional detection module is used to detect terahertz waves generated in a liquid terahertz radiation system. Through simple installation, the multi-dimensional detection module is connected to the operating platform via a rotating screw. The detection module is placed directly below the center of the liquid medium, aligning the flow direction of the water line (or other shaped medium) with the center of the micro protractor in the detection module. This optimizes the relative position of the water line and the detection module, making multi-angle detection more accurate and reducing disturbances. The detection device consists of three layers: the first layer rotates, the second layer slides, and the third layer is an integrated detection module capable of both coherent and incoherent detection. The three layers are connected by threads, making installation simple and enabling easy detection of terahertz waves.

[0010] The laser focusing module includes a laser, an oscillator, an amplifier, and several focusing lenses.

[0011] The laser is an electro-optical conversion device that generates a continuous laser beam when powered on. The oscillator can convert the continuous laser beam into a discrete laser beam. The amplifier can amplify the discrete laser beam using chirped pulse amplification technology to finally obtain a stable laser beam that we can use. The several focusing lenses can accurately focus the laser beam onto the liquid medium through a certain focal length, so that the laser beam can generate optimal interaction with the liquid medium, thereby radiating stronger terahertz waves.

[0012] The liquid circulation module includes a temperature control module, a liquid circulation control module, a position control module, and a nozzle.

[0013] The temperature control module includes a heating device, a cooling device, a temperature sensor, and a control circuit. Temperature control is achieved through the connection between the control circuit and each device, using negative feedback to intelligently and automatically adjust the temperature of the liquid medium.

[0014] The liquid circulation control module includes a water tank, a water pressure gauge, a turbine water pump, and a flow meter. These components are connected by flexible water pipes, which allows the liquid medium to circulate. The module can also detect and regulate state parameters such as hydraulic pressure and flow rate by adjusting the flow meter and water pressure gauge.

[0015] The position control module can be a high-precision three-dimensional moving platform, which can adjust the relative position of the liquid medium. By optimizing the three-dimensional moving platform, the laser and the medium can be closely focused.

[0016] The nozzle can be needle-shaped, groove-shaped, or custom-designed. A needle-shaped nozzle can generate the water line required for a liquid terahertz radiation system, a groove-shaped nozzle can generate the water film required for a liquid terahertz radiation system, and a custom-designed nozzle can generate other shapes required for a liquid terahertz radiation system. The size of the medium can be changed by changing the shape of the nozzle.

[0017] The multi-dimensional detection device consists of a multi-layer structure, which can be mainly divided into a bottom layer structure, a middle layer structure, and an upper layer structure.

[0018] The bottom layer structure consists of a rotating unit, a micro protractor, a pointer, a splash-proof device, and a scale. The rotating unit is a structural component of a specific shape cut from an acrylic sheet. A micro protractor is installed at the arc of the rotating unit and is connected to the rotating unit by an adhesive substance. The rotating unit is connected to the operating platform via a rotating screw to achieve wide-angle rotation. The pointer is mounted on the operating platform and points to the micro protractor for accurate wide-angle measurement. The splash-proof device is funnel-shaped and mounted on the rotating screw to store and recover liquid media, preventing liquid media from contaminating the operating platform. The scale is connected to the bottom of the bottom layer structure and serves as a ruler for the sliding of the middle layer structure.

[0019] The middle layer structure consists of precision slide rails and a lifting device. This layer structure enables three-dimensional movement. The precision slide rails are threadedly connected to the middle of the bottom and upper layers. The lifting device consists of four rounded, adjustable positioning screws, providing support and lifting functions. The precision slide rails allow for horizontal movement of the upper detection module, and changing the threaded connection method enables vertical movement of the upper structure. The upper structure can achieve overall three-dimensional movement control of the integrated detection device through the precision slide rails and lifting device.

[0020] The upper structure is a terahertz detection integrated module, including an optical array plate, a first off-axis parabolic mirror, a chopper, a silicon wafer, a second off-axis parabolic mirror, a sealing device, and a PED pyroelectric detector.

[0021] The optical array plate is customized from an optical breadboard according to the size of the detection module, and can accurately position, install, and fix terahertz detection-related devices.

[0022] The first off-axis parabolic mirror is used to collect terahertz generated in the liquid medium and collimate it to the second off-axis parabolic mirror.

[0023] The chopper is positioned between the first off-axis parabolic mirror and the silicon wafer to modulate the measured continuous terahertz pulses into terahertz pulses with a fixed frequency and output the modulation frequency to the PED pyroelectric detector.

[0024] The filter, which can be a silicon wafer, is used to filter out residual pump light, thus performing a filtering function. The second off-axis parabolic mirror acts as a focusing lens, focusing the modulated and filtered terahertz pulse onto the PED pyroelectric detector.

[0025] The PED pyroelectric detector is a terahertz detector made of a crystal with pyroelectric properties. The pyroelectric detector uses the temperature change of the pyroelectric crystal when it is irradiated, and the resulting voltage change, to measure the energy irradiated on the crystal. The pyroelectric detector has a simple structure and is easy to operate.

[0026] The integrated terahertz detection module is highly scalable and can also achieve incoherent detection. By changing the structure of the optical path, the laser from the laser focusing module is divided into pump light and probe light. The pump light is used to excite the liquid medium to radiate terahertz waves, and the probe light passes through a second off-axis parabolic mirror and is collinear with the terahertz radiation through a crystal with an electro-optic effect. The electric field of the terahertz radiation changes the refractive index of the crystal, thus giving the crystal birefringence. The electric field intensity of the terahertz radiation can be obtained by measuring the ellipticity of the probe light.

[0027] The sealed device is a box made of simple, lightweight and portable composite material. This structure is installed outside the off-axis parabolic mirror. During the detection process, a protective gas is added to this structure to control the diffusion environment during the detection process and reduce the absorption of terahertz waves in the air.

[0028] The multi-layered structure described in this invention utilizes threaded connections, a widely used detachable and fixed connection method that offers advantages such as simple structure, reliable connection, and ease of disassembly. This device is constructed from high-temperature resistant, corrosion-resistant, lightweight, and portable materials to accommodate slightly corrosive and flammable liquid media. Combining the advantages of threaded connections, it exhibits high portability, simple construction, low cost, and ease of disassembly and assembly. The device's compact and integrated design makes it easy to carry and suitable for various occasions.

[0029] The beneficial effects of this invention are: This invention enables multi-dimensional integrated detection of the radiation modes of liquid terahertz radiation, which is beneficial for further elucidating the spatial and intensity distribution of terahertz waves. It provides a powerful method for studying the radiation modes of liquid terahertz radiation by controlling the dispersion environment during the detection process through a sealed device, thereby reducing the absorption of terahertz waves in the air. This detection device has a simple structure, low cost, and excellent maintainability and expandability, possessing significant practical and scientific research value. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of the present invention;

[0031] In the diagram: 100-Laser focusing module, 120-Focusing lens, 200-Multi-dimensional detection module, 210-Miniature protractor, 220-Rotation unit, 230-First off-axis parabolic mirror, 240-Sliding unit, 250-Chopper, 260-Filter, 270-Second off-axis parabolic mirror, 280-Pyroelectric detector, 290-Sealed device. Detailed Implementation

[0032] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0033] Example 1: Any liquid terahertz radiation system can be selected, for example, liquid water can be used as the excitation medium for the experiment. Figure 1 As shown, an integrated detection device for a liquid terahertz radiation system includes a laser focusing module 100, a liquid circulation module, and a multi-dimensional detection module 200. The laser focusing module 100 generates an excitation laser, which acts on the liquid water lines generated by the liquid circulation device, thereby radiating terahertz waves. The multi-dimensional detection module 200 performs multi-dimensional detection on the radiated terahertz waves, thus exploring the spatial distribution of terahertz waves. This allows for the direct identification of the strongest terahertz radiation in space without the need for terahertz wave enhancement.

[0034] The laser focusing module 100 can be composed of a Leo50 femtosecond laser oscillator, a Tolar527 laser, and a laser amplifier. The laser focusing module 100 can generate a laser beam with a center wavelength of 800 nm, a pulse width of 50 fs, and a repetition frequency of 1 kHz. Specifically, the laser is generated by the Leo50 femtosecond laser oscillator producing a discrete seed laser beam, which is then amplified by the Tolar527 excitation amplifier to obtain the high-intensity, stable laser required for our experiment. The generated laser is focused into the liquid medium through a total reflection mirror and a 60 μm focusing lens 120, interacting with the medium to radiate terahertz waves.

[0035] The liquid circulation module includes a temperature control module, a position control module, and a liquid circulation control module. These modules are used to create the different sizes and shapes of the liquid media required in the liquid terahertz radiation system.

[0036] The temperature control module includes a heating device, a cooling device, a temperature sensor, and a control circuit. Temperature control is achieved by connecting the control circuit to each device, and intelligent automatic adjustment of the liquid medium temperature is performed through negative feedback. The heating device can be a heating rod, and the cooling device can be a cooling machine. In this embodiment, the temperature is set to 5°C.

[0037] The position control module can be a high-precision three-dimensional moving bracket used to install flexible hoses in the liquid circulation control system and optimize the relative position of the liquid medium.

[0038] The liquid circulation control module can consist of a water tank, a water pump, a pressure gauge, a flow meter, and a flexible hose, used to regulate the hydraulic pressure and flow rate of the liquid medium. Water is pumped from the tank and delivered to the hose by the water pump. The flow rate is adjusted by regulating the pump power. The pressure gauge and flow meter monitor the water pressure and flow rate. The nozzle generates the required medium size and shape for the liquid terahertz radiation system. In this embodiment, a 150µm water line is generated. The laser generated by the laser focusing module 100 interacts with the water line, radiating terahertz waves. The medium can then flow back into the tank, achieving liquid medium circulation.

[0039] The present invention provides an integrated detection device for a liquid terahertz radiation system, comprising a multi-dimensional detection module 200, which can detect the intensity distribution in terahertz wave space in multiple dimensions. The multi-dimensional detection device consists of a multi-layer structure, mainly divided into a bottom layer structure, a middle layer structure, and an upper layer structure.

[0040] The bottom layer structure consists of a rotating unit 220, a miniature protractor 210, a pointer, a splash-proof device, and a ruler. The rotating unit 220 can be a structural component of a specific shape, cut from a 40cm x 50cm acrylic sheet. A miniature protractor 210 is installed at the arc of the rotating unit 220. The miniature protractor 210 can be a circle cut from an acrylic sheet with a radius of 5cm and connected to the rotating unit 220 with an adhesive material. The rotating unit 220 is connected to the operating platform via a rotating screw, enabling wide-angle rotation. The pointer, mounted on the operating platform, points to the miniature protractor 210, enabling accurate wide-angle measurement. The splash-proof device, made of quartz glass and shaped like a funnel, is installed on the rotating screw to store and recover liquid media, preventing liquid contamination of the operating platform. A 20cm ruler is connected to the bottom of the bottom layer structure, serving as a scale for the sliding of the middle layer structure.

[0041] The middle layer structure consists of precision slide rails and a lifting device. This layer structure enables three-dimensional movement. The precision slide rails are threadedly connected to the middle of the bottom and upper layers. The lifting device consists of four rounded, adjustable positioning screws, providing support and lifting functions. The precision slide rails allow for horizontal movement of the upper detection module, and changing the threaded connection method enables vertical movement of the upper structure. The upper structure can achieve overall three-dimensional movement control of the integrated detection device through the precision slide rails and lifting device.

[0042] The upper structure is an integrated terahertz detection module, including an optical array plate, a first off-axis parabolic mirror 230, a chopper 250, a silicon wafer, a second off-axis parabolic mirror 270, a sealing device 290, and a PED pyroelectric detector 280. The optical array plate is customized from an optical breadboard according to the size of the detection module. In this embodiment, the size of the optical breadboard can be 35cm*35cm. The array holes of the breadboard allow for precise positioning, installation, and fixation of terahertz detection-related devices.

[0043] In the device of this invention, an excitation laser generated by a laser focusing module 100 acts on a liquid water line, radiating terahertz waves. These waves are collected by a first off-axis parabolic mirror 230 and transmitted to a next off-axis parabolic mirror. A chopper 250 and a filter 260 are provided between the two parabolic mirrors. The chopper 250 modulates the frequency of the terahertz pulse, and the filter 260 filters out stray light remaining from the pump light. Finally, the light is focused by a second off-axis parabolic mirror 270 onto a pyroelectric detector 280. In this embodiment, the pyroelectric detector 280 can be a triglyceride-based detector. The detector, which is made of pyroelectric crystal, can be surrounded by a sealed device 290. Nitrogen gas is added to the sealed device 290 to control the diffusion environment of the detection process and reduce the excessive absorption of terahertz waves by the air. By rotating the multi-dimensional detection module 200 around the water line, terahertz waves within a 360° range of the liquid water line can be detected. At the same time, by changing and optimizing the relative position of the multi-dimensional detection module 200, the intensity distribution of terahertz waves radiated around the water line can be explored. Finally, the strongest terahertz waves radiated around the water line can be accurately detected.

[0044] This invention also provides a terahertz wave-based detection method applicable to terahertz detection using various terahertz excitation methods. The method includes the use of a liquid terahertz radiation system, such as air as the excitation medium. A laser beam with a center wavelength of 800 nm, a pulse width of 50 fs, and a repetition frequency of 1 kHz is generated by a laser focusing module. This laser beam is focused into the air medium by a 60 μm focusing lens 120, interacting with the air to form an air plasma filament, thereby radiating terahertz waves.

[0045] The radiated terahertz waves are collected by a first off-axis parabolic mirror 230 and collimated into a second off-axis parabolic mirror 270. A chopper 250 and a filter 260 are added between the two off-axis parabolic mirrors. The chopper 250, positioned between the first off-axis parabolic mirror and the filter, modulates the measured continuous terahertz pulses into terahertz pulses with a fixed frequency and outputs the modulation frequency to the PED pyroelectric detector. To ensure relatively accurate terahertz detection, the filter 260 can be a silicon wafer used to filter out unwanted stray light. The collimated terahertz waves are then focused into a pyroelectric detector 280 by the second off-axis parabolic mirror 270. In this method, the pyroelectric detector is a terahertz detector made of a crystal with pyroelectric properties. The pyroelectric detector measures the energy radiated onto the crystal by measuring the voltage change caused by the temperature change of the pyroelectric crystal when it is irradiated. This pyroelectric detector has a simple structure and is easy to operate.

[0046] It should be noted that by rotating the multi-dimensional detection module around the waterline, terahertz waves within a 360° range of the liquid waterline can be detected. At the same time, by changing and optimizing the relative position of the multi-dimensional detection module, the intensity distribution of terahertz waves radiated around the waterline can be explored, and finally, the strongest terahertz waves radiated around the waterline can be accurately detected.

[0047] The terahertz wave-based detection method provided in this invention can directly detect the excited terahertz waves and find the strongest terahertz distribution in space through the device of this invention, without the need for other means to enhance the terahertz waves. At the same time, this detection method involves fewer experimental components, has a simple structure, is easy to implement, has low cost, and is highly maintainable and scalable.

[0048] The specific embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. An integrated detection device for a liquid terahertz radiation system, characterized in that, include: The laser focusing module is used to generate a laser beam with a center wavelength of 800nm. Through a focusing lens with a focal length of 60μm, the laser can be precisely focused on the liquid medium. The liquid circulation module is used to generate the required liquid shape, size, and state in the liquid terahertz radiation system. A multi-dimensional detection module is used to detect terahertz waves generated in a liquid terahertz radiation system; The multi-dimensional detection module has a multi-layer structure, consisting of a bottom layer, a middle layer, and a top layer. The bottom layer structure consists of a rotating unit, a micro protractor, a pointer, a splash guard, and a scale. The rotating unit is a structural component cut from an acrylic sheet. The micro protractor is connected to the rotating unit by an adhesive substance. The rotating unit is connected to the operating platform by a rotating screw to achieve wide-angle rotation. The pointer is mounted on the operating platform and points to the micro protractor for wide-angle accurate measurement. The splash guard is funnel-shaped and mounted on the rotating screw for the storage and recovery of liquid media and to prevent liquid media from contaminating the operating platform. The scale is connected to the bottom of the bottom layer structure and serves as a ruler for the sliding of the middle layer structure. The middle layer structure consists of a precision slide rail and a lifting device. This layer structure enables three-dimensional movement. The precision slide rail is connected to the middle of the bottom and upper layers of the structure by threads. The lifting device consists of four rounded, position-adjustable positioning screws, which serve as supports and lifts the structure. The upper structure is a terahertz detection integrated module, including an optical array plate, a first off-axis parabolic mirror, a chopper, a silicon wafer, a second off-axis parabolic mirror, a sealing device, and a PED pyroelectric detector. The optical array plate is used for positioning, mounting, and fixing terahertz detection-related devices. The first off-axis parabolic mirror is used to collect terahertz generated in the liquid medium and collimate it to the second off-axis parabolic mirror; The chopper is positioned between the first off-axis parabolic mirror and the silicon wafer, and is used to modulate the measured continuous terahertz pulses into terahertz pulses with a fixed frequency, and output the modulation frequency to the PED pyroelectric detector. Silicon wafers are used to filter out residual pump light, thus acting as a filter. The second off-axis parabolic mirror serves a focusing function, used to focus the modulated and filtered terahertz pulses onto the PED pyroelectric detector; The PED pyroelectric detector is a terahertz detector made of a crystal with pyroelectric properties. The PED pyroelectric detector uses the temperature change of the pyroelectric crystal when it is irradiated, and the resulting voltage change, to measure the energy irradiated on the crystal.

2. The integrated detection device for the liquid terahertz radiation system according to claim 1, characterized in that: The laser focusing module includes a laser, an oscillator, an amplifier, and multiple focusing lenses. The laser is an electro-optical conversion device that generates a continuous laser beam when powered on. The oscillator converts the continuous laser beam into a discrete laser beam. The amplifier amplifies the discrete laser beam using chirped pulse amplification technology. The focusing lenses accurately focus the laser beam onto the liquid medium.

3. The integrated detection device for the liquid terahertz radiation system according to claim 1, characterized in that: The liquid circulation module includes a temperature control module, a liquid circulation control module, a position control module, and a nozzle; The temperature control module includes a heating device, a cooling device, a temperature sensor, and a control circuit. Temperature control is achieved by connecting the control circuit to each device and intelligently and automatically adjusting the temperature of the liquid medium through negative feedback. The liquid circulation control module includes a water tank, a water pressure gauge, a turbine water pump, and a flow meter; each component is connected by a flexible water pipe, which enables the liquid medium to circulate and flow, and the hydraulic pressure and flow rate can be detected and controlled by adjusting the flow meter and water pressure gauge. The position control module is a high-precision three-dimensional moving platform that adjusts the relative position of the liquid medium and optimizes the three-dimensional moving platform to achieve a close focusing position between the laser and the medium. The nozzle can be needle-type, groove-type, or custom-designed. A needle-type nozzle generates the water line required for the liquid terahertz radiation system, a groove-type nozzle generates the water film required for the liquid terahertz radiation system, and a custom-designed nozzle generates other shapes required for the liquid terahertz radiation system. The size of the medium can be changed by changing the shape of the nozzle.

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