A Portable Terahertz Solid-State Source Interferometer

Abstract

The present invention discloses a portable terahertz solid source interferometer, which includes an interferometer box body, a main optical path platform, a detection and data processing platform, and a plasma detection platform. The three modular platforms of the main optical path platform, the detection and data processing platform, and the plasma detection platform are fixed on the bottom plate of the interferometer box body. The interferometer uses two terahertz solid sources with selectable frequencies as light sources, generates a heterodyne signal through the dual-laser method, and uses the heterodyne interferometer optical path to measure the plasma electron density. This device can solve the problem of convenient measurement of the plasma electron density of most plasma generating devices. By designing the specific structure of the portable terahertz solid source interferometer, a compact, movable, and easy-to-operate system layout is realized, and it is applicable to multiple scenarios and a wide plasma density range, providing a convenient and fast measurement tool for plasma density measurement.

Description

Technical Field

[0001] The present invention relates to the field of optical technology, and in particular to a portable terahertz solid source interferometer. Background Art

[0002] A plasma is an aggregate composed of positively and negatively charged ions and electrons, and may also include some neutral atoms and molecules. Generally, it is electrically neutral macroscopically. A plasma can be in a solid, liquid, or gaseous state. An ionized gas is a gaseous plasma. The basic process in a plasma is the interaction between various charged particles under the action of an electric field and a magnetic field, causing various effects. A terahertz laser interferometer is an instrument for measuring the electron density of a plasma using a light source in the terahertz band. The interferometer system calculates the line integral electron density generated by the plasma by measuring the phase change generated by the plasma. This non-contact absolute measurement makes the terahertz laser interferometer one of the most accurate and reliable tools for plasma density diagnosis.

[0003] Currently, civilian equipment with functions such as plasma sterilization and plasma cleaning requires plasma density testing during research, testing, and factory production to calibrate detailed plasma parameters. Major plasma research laboratories in China also need to measure the plasma electron density. The low-temperature plasma research devices and space plasma research devices developed in China also require plasma density measurement. However, most instrument devices and installations only need single or few plasma measurements for calibration and do not need to purchase a complete set of interferometer systems. At present, the price of a terahertz laser interferometer system is expensive, generally not less than one million yuan per set, and there are no commercialized devices of terahertz laser interferometers on the market. The necessity and cost consideration of customizing a set of systems limit the development of a large part of research units and manufacturers.

[0004] Therefore, how to design a productized terahertz laser interferometer with a small volume, movable, stable operation, and strong applicability has become a technical problem that needs to be urgently solved by those skilled in the art today. Summary of the Invention

[0005] The present invention provides a portable terahertz solid source interferometer to solve the problem of convenient measurement of the plasma electron density of most plasma generating devices. By designing the specific structure of the portable terahertz solid source interferometer, a compact, movable, and easy-to-operate system layout is realized, providing a convenient and fast measurement tool for plasma density measurement.

[0006] The present invention provides a portable terahertz solid source interferometer, including an interferometer box body, a main optical path platform, a detection and data processing platform, and a plasma detection platform;

[0007] The interferometer box body is the support and outer package of the entire interferometer. The three modular platforms, namely the main optical path platform, the detection and data processing platform, and the plasma detection platform, are fixed on the bottom plate of the box body. There are two parallel guide rails on the bottom plate of the box body. The main optical path platform and the detection and data processing platform can be translated left and right on the guide rails. The interferometer optical path is installed on the two platforms. The plasma detection platform is fixed at the center position of the box body. A data display screen is installed on the side of the box body. When it needs to be moved over a long distance, the box body can be folded. At this time, the plasma detection platform becomes the side plate, and the main optical path platform and the detection and data processing platform are stacked on top of each other, and side plates are added to form a sealed box body, reducing the overall occupied area and improving the compactness;

[0008] The main optical path platform is equipped with a first terahertz solid source, a second terahertz solid source, a reference channel detector, and some interferometer optical path devices. The optical signal transmitting ends of the first terahertz solid source and the second terahertz solid source are connected to the interferometer optical path. The terahertz light emitted by the two terahertz solid sources enters the reference channel detector through the interferometer optical path;

[0009] The detection and data processing platform is equipped with a detection channel detector, a phase comparison and acquisition system, a small industrial control computer, and some interferometer optical path devices. The detection channel detector receives the terahertz light emitted by the two terahertz solid sources;

[0010] The interferometer optical path includes a first beam splitter, a second beam splitter, a third beam splitter, a fourth beam splitter, a first plane mirror, a second plane mirror, a first convex mirror, a second convex mirror, a first concave mirror, and a second concave mirror;

[0011] The optical signal transmitting end of the first terahertz solid source is sequentially connected to the receiving end of the reference channel detector through the first beam splitter and the second beam splitter; The optical signal transmitting end of the first terahertz solid source is sequentially connected to the receiving end of the detection channel detector through the first beam splitter, the first convex mirror, the first concave mirror, the second plane mirror, and the fourth beam splitter;

[0012] The optical signal transmitting end of the second terahertz solid source is sequentially connected to the receiving end of the detection channel detector through the third beam splitter, the first plane mirror, the second convex mirror, the second concave mirror, the plasma to be detected, and the fourth beam splitter.

[0013] As one of the preferred solutions, the first convex mirror and the first concave mirror, and the second convex mirror and the second concave mirror form two sets of telescope systems. By adjusting the distances between the first convex mirror and the first concave mirror, and the second convex mirror and the second concave mirror, the optical path adjustment between the main optical path platform and the detection and data processing platform is achieved.

[0014] As one of the preferred solutions, the first terahertz solid source is a frequency-converting solid source, and the second terahertz solid source is a fixed-frequency solid source. The fundamental frequencies of the two solid sources are the same. By adjusting the frequency difference of 0.1 - 10 MHz in the megahertz range of the first terahertz solid source, the difference frequency adjustment between the two sources is achieved. The first terahertz solid source and the second terahertz solid source can be replaced with terahertz solid sources of different frequencies from 0.1 THz to 0.65 THz according to the electron density requirements of the measurement object.

[0015] As one of the preferred solutions, the phase comparison and acquisition system continuously receives the sine wave measurement signals output by the reference channel detector and the detection channel detector, performs phase calculation, storage, and output. The phase comparison and acquisition system transmits the processed density information to the small industrial control computer, and the small industrial control computer plots the data into a data graph and displays it in real time on the display screen on the side of the box.

[0016] Compared with the prior art, the beneficial effects of the embodiments of the present invention are at least one of the following:

[0017] (1) Selecting terahertz solid sources of different bands, which are small in volume, compact in structure, low in environmental sensitivity, and stable in output signal, can realize the measurement of plasma density in different electron density ranges.

[0018] (2) The heterodyne interferometer optical path system implemented by the dual-laser method has strong anti-interference ability, low requirements for the light intensity of the interferometer, and high time resolution.

[0019] (3) The portable terahertz solid source interferometer of the present invention has the entire system encapsulated in a box, can complete the functions of a terahertz laser interferometer without adding supporting equipment. It is small in volume, easy to move and carry, uses few optical devices, has low cost, and can realize continuous and stable measurement of plasma electron density.

[0020] (4) The portable terahertz solid source interferometer of the present invention has a modular design for 3 platforms, is not only applicable to small plasma civilian equipment, but also applicable to large plasma experimental devices after being disassembled, is not limited by the size of the measurement object, and greatly improves the applicable scenarios and objects of the instrument. Description of the Drawings

[0021] Figure 1 is a schematic structural diagram of a portable terahertz solid source interferometer in one of the embodiments of the present invention;

[0022] Figure 2 is a schematic principle diagram after folding a portable terahertz solid source interferometer in one of the embodiments of the present invention;

[0023] Reference Numerals:

[0024] Among them, 1. Interferometer box body; 2. Main optical path platform; 3. Detection and data processing platform; 4. Plasma detection platform; 5. First terahertz solid source; 6. Second terahertz solid source; 7. Reference channel detector; 8. Detection channel detector; 9. Phase comparison and acquisition system; 10. Small industrial control computer; 11. Double guide rails; 12. Display screen; 13. First beam splitter; 14. Second beam splitter; 15. Third beam splitter; 16. Fourth beam splitter; 17. First plane mirror; 18. Second plane mirror; 19. First convex mirror; 20. Second convex mirror; 21. First concave mirror; 22. Second concave mirror; P: Plasma. Specific implementation manners

[0025] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0026] In the description of this application, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first", "second", "third", etc. may explicitly or implicitly include one or more of such features. In the description of this application, unless otherwise specified, the meaning of "a plurality" is two or more.

[0027] In the description of this application, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. The terms "vertical", "horizontal", "left", "right", "up", "down" and similar expressions used herein are only for the purpose of illustration and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation to the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0028] In the description of the present application, it should be noted that unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0029] An embodiment of the present invention provides a portable terahertz solid source interferometer. Specifically, please refer to Figure 1 , Figure 1 which shows a schematic structural diagram of a portable terahertz solid source interferometer in one of the embodiments of the present invention, and it includes an interferometer box body 1, a main optical path platform 2, a detection and data processing platform 3, and a plasma detection platform 4.

[0030] The interferometer box body 1 is the support and outer package box body of the entire interferometer. The three modular platforms of the main optical path platform 2, the detection and data processing platform 3, and the plasma detection platform 4 are fixed on the box body bottom plate. There are two parallel double guide rails 11 on the box body bottom plate. The main optical path platform 2 and the detection and data processing platform 3 can translate left and right on the double guide rails 11, and the interferometer optical paths are installed on the two platforms. The plasma detection platform 4 is fixed at the center position of the box body. A data display screen 12 is installed on the side of the box body. When it needs to be moved over a long distance, the box body can be folded. At this time, the plasma detection platform 4 is the side plate (without the item to be detected), and the main optical path platform 2 and the detection and data processing platform 3 are stacked on top of each other, and side plates are added to form a sealed box body, reducing the overall occupied area and improving the compactness.

[0031] The main optical path platform 2 is equipped with a first terahertz solid source 5, a second terahertz solid source 6, a reference channel detector 7, and some interferometer optical path devices. The optical signal transmission ends of the first terahertz solid source 5 and the second terahertz solid source 6 are connected to the interferometer optical path, and the terahertz light emitted by the two terahertz solid sources enters the reference channel detector 7 through the interferometer optical path;

[0032] The detection and data processing platform 3 is equipped with a detection channel detector 8, a phase comparison and acquisition system 9, a small industrial control computer 10, and some interferometer optical path devices. The detection channel detector 8 receives the terahertz light emitted by the two terahertz solid sources.

[0033] It should be noted that through research on terahertz technology, the inventor has applied a terahertz solid source with small volume, compact structure, low ring sensitivity, and stable output signal to the interferometer system. For example, the terahertz solid source in this embodiment has a small volume, a compact structure, and a solid source with a frequency selectable from 0.1 THz to 0.65 THz. It has a wider applicable electron density range, and the minimum output power can exceed 5 mW, meeting the power requirements of the single-channel interferometer light source. The difference frequency output is stable. Using two solid sources as the light source of the interferometer system for heterodyne interferometric measurement, it has strong anti-interference ability and a compact design, greatly reducing the volume and mobility of the entire interferometer system. This system has excellent measurement accuracy within the plasma density range of 1×10 15 m -3 ~1×10 20 m -3 and can be used for density measurement of industrial products such as plasma sterilization systems or large plasma research devices, providing reliable measurement data.

[0034] Preferably, in this embodiment, the first terahertz solid source 5 is a frequency-converting solid source, and the second terahertz solid source 6 is a fixed-frequency solid source. By using the dual-laser method, the difference frequency between the two solid sources can be arbitrarily adjusted within the range of 0.1~10 MHz to achieve different time-resolution measurements.

[0035] In the above embodiment, the interferometer optical path is designed as a heterodyne interferometer optical path. It is necessary to adjust the solid source with adjustable frequency so that there is a frequency difference of 0.1~10 MHz between this laser and the fixed-frequency solid source. After the light beams generated by the two lasers are combined and enter the detector, the difference frequency signal corresponding to the frequency can be obtained. In the optical path design, one optical path passing through the plasma in the device is designed as the detection optical path, and the other optical path not passing through the plasma is designed as the reference optical path. When the plasma detection platform 4 is placed in the plasma generation device, the detection channel can detect the phase shift generated by the laser in the plasma. After the phase comparison and acquisition system 9 performs heterodyne comparison on the detection channel signal and the reference channel signal, the plasma electron density can be calculated.

[0036] Furthermore, in this embodiment, the interferometer optical path includes a first beam splitter 13, a second beam splitter 14, a third beam splitter 15, a fourth beam splitter 16, a first plane mirror 17, a second plane mirror 18, a first convex mirror 19, a second convex mirror 20, a first concave mirror 21, a second concave mirror 22, and the plasma to be detected;

[0037] The optical signal transmitting end of the first terahertz solid source 5 is sequentially connected to the receiving end of the reference channel detector 7 through the first beam splitter 13 and the second beam splitter 14; the optical signal transmitting end of the first terahertz solid source 5 is sequentially connected to the receiving end of the detection channel detector 8 through the first beam splitter 13, the first convex mirror 19, the first concave mirror 21, the second plane mirror 18 and the fourth beam splitter 16;

[0038] The optical signal transmitting end of the second terahertz solid source 6 is sequentially connected to the receiving end of the detection channel detector 8 through the third beam splitter 15, the first plane mirror 17, the second convex mirror 20, the second concave mirror 22, the plasma P to be detected and the fourth beam splitter 16.

[0039] Further, the first convex mirror 19 and the first concave mirror 21, and the second convex mirror 20 and the second concave mirror 22 form two sets of telescope systems. By adjusting the distance between the first convex mirror 19 and the first concave mirror 21 or the second convex mirror 20 and the second concave mirror 22, the optical path adjustment between the main optical path platform 2 and the detection and data processing platform 3 is realized, which is convenient for the design and adjustment of the Gaussian beam for long-distance transmission;

[0040] Further, the phase comparison and acquisition system 9 continuously receives the sine wave measurement signals output by the reference channel detector 7 and the detection channel detector 8, and performs phase calculation, storage and output. The phase comparison and acquisition system 9 transmits the processed density information to the small industrial control computer 10, and the small industrial control computer 10 draws the data into a data graph and displays it in real time on the display screen 12 on the side of the box body.

[0041] The portable terahertz solid source interferometer provided by the embodiment of the present invention has the beneficial effects in at least one of the following:

[0042] (1) Terahertz solid sources of different bands are selected, which are small in volume, compact in structure, low in environmental sensitivity, and stable in output signal, and can realize the measurement of plasma density in different electron density ranges.

[0043] (2) The heterodyne interferometer optical path system realized by the double-laser method has strong anti-interference ability, low requirement for the light intensity of the interferometer, and high time resolution.

[0044] (3) The portable terahertz solid source interferometer of the present invention has the whole system encapsulated in a box body, and has the function of completing a terahertz laser interferometer without adding supporting equipment. It is small in volume, convenient to move and carry, uses few optical devices, has low cost, and can realize continuous and stable measurement of plasma electron density.

[0045] (4)The portable terahertz solid source interferometer of the present invention has a modular design for three platforms. It is not only applicable to small-scale civilian plasma devices, but also applicable to large-scale plasma experimental devices after being disassembled, without being limited by the size of the measurement object, greatly improving the applicable scenarios and objects of the instrument.

[0046] The above embodiments only represent several implementation manners of the present invention, and the description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the appended claims.

Claims

1. A portable terahertz solid source interferometer, characterized in that: It includes an interferometer box, a main optical path platform, a detection and data processing platform, and a plasma detection platform; The interferometer box is a support and outer packaging box for the entire interferometer. The three modular platforms of the main optical path platform, the detection and data processing platform, and the plasma detection platform are fixed on the bottom plate of the box. There are two parallel guide rails on the bottom plate of the box. The main optical path platform and the detection and data processing platform can be translated left and right on the guide rails. The interferometer optical path is installed on the two platforms. The plasma detection platform is fixed at the center of the box. A data display screen is installed on the side of the box. When long-distance movement is required, the box can be folded. At this time, the plasma detection platform is a side panel, and the main optical path platform and the detection and data processing platform are stacked up and down. The side panels are added to form a closed box, which reduces the overall occupied area and improves compactness. The main optical path platform is equipped with a first terahertz solid source, a second terahertz solid source, a reference track detector and part of the interferometer optical path components. The optical signal sending ends of the first terahertz solid source and the second terahertz solid source are connected to the interferometer optical path. The terahertz light emitted by the two terahertz solid sources enters the reference track detector through the interferometer optical path. The detection and data processing platform is equipped with a detection channel detector, a phase comparison and acquisition system, a small industrial computer and some interferometer optical path devices, and the detection channel detector receives the terahertz light emitted by two terahertz solid sources; The interferometer optical path includes a first beam splitter, a second beam splitter, a third beam splitter, a fourth beam splitter, a first plane reflector, a second plane reflector, a first convex reflector, a second convex reflector, a first concave reflector, and a second concave reflector; The optical signal transmitting end of the first terahertz solid source is connected to the receiving end of the reference track detector through the first beam splitter and the second beam splitter in sequence; the optical signal transmitting end of the first terahertz solid source is connected to the receiving end of the detection track detector through the first beam splitter, the first convex reflector, the first concave reflector, the second plane reflector and the fourth beam splitter in sequence; The optical signal sending end of the second terahertz solid source is connected to the receiving end of the detection channel detector through the third beam splitter, the first plane reflector, the second convex reflector, the second concave reflector, the plasma to be detected and the fourth beam splitter in sequence.

2. The portable terahertz solid source interferometer according to claim 1, characterized in that: The first convex mirror and the first concave mirror, the second convex mirror and the second concave mirror form two sets of telescope systems. By adjusting the distance between the first convex mirror and the first concave mirror, and the second convex mirror and the second concave mirror, the optical path adjustment between the main optical path platform and the detection and data processing platform is achieved.

3. The portable terahertz solid source interferometer according to claim 1, characterized in that: The first terahertz solid source is a variable frequency solid source, and the second terahertz solid source is a fixed frequency solid source. The fundamental frequencies of the two solid sources are the same. The frequency difference adjustment between the two sources is achieved by adjusting the frequency difference of the first terahertz solid source in the megahertz range of 0.1 to 10 MHz. The first terahertz solid source and the second terahertz solid source can be replaced with terahertz solid sources of different frequencies of 0.1 THz to 0.65 THz according to the electron density requirements of the measured object.

4. The portable terahertz solid source interferometer according to claim 1, characterized in that: The phase comparison and acquisition system continuously receives the sinusoidal wave measurement signals output by the reference channel detector and the detection channel detector, and performs phase calculation, storage and output. The phase comparison and acquisition system transmits the processed density information to a small industrial computer, and the small industrial computer draws the data into a data graph, which is then displayed in real time on a display screen on the side of the box.

Images