CN111323385B - Terahertz camera, terahertz imaging system and application - Google Patents
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Abstract
The embodiment of the invention provides a terahertz camera and a terahertz imaging system, wherein the terahertz camera comprises: a P-N junction cell array and a processing module; the P-N junction unit array comprises a plurality of P-N junction units, and the processing module is electrically connected with each P-N junction unit respectively; the P-N junction unit array is used for converting the received terahertz waves into voltage signals, and the processing module is used for determining the light spot profile of the terahertz waves according to the voltage signals obtained by conversion of the P-N junction unit array. According to the embodiment of the invention, the P-N junction unit array is adopted to construct the terahertz camera, the terahertz camera is not limited by temperature and surrounding environment, the imaging speed is high, the size is small, the operation is simple, the cost is low, the P-N junction unit has high detection sensitivity to terahertz waves, even if weak terahertz waves are focused, high-quality focused light spots can be obtained on the P-N junction unit array, and further the imaging of an object to be imaged is clearer.
Description
Technical Field
The invention belongs to the technical field of photoelectric devices, and particularly relates to a terahertz camera, a terahertz imaging system and application.
Background
Terahertz waves are electromagnetic waves with the frequency ranging from 0.1THz to 30THz, the wavelength is approximately ranging from 0.03 mm to 3mm, the terahertz waves are located between far infrared and millimeter waves on an electromagnetic spectrum, and the terahertz waves have important application in various fields such as wireless communication, public safety, astronomy, medical imaging, ultrafast spectrum and the like. The special position of the frequency band of the terahertz wave gives the frequency band special properties, such as the vibration level and the rotation level of the biological macromolecules corresponding to the terahertz frequency, the hydrogen bond energy and the van der Waals force energy corresponding to water molecules, and a plurality of biological molecules have fingerprint spectra in the frequency band and can be applied to material identification and recognition; the terahertz frequency band means larger information capacity, and provides a better communication means for communication remote sensing and aerospace. Compared with visible light, the terahertz wave has longer wavelength and better penetrating capability, is transparent to clothes, fur, paper, leather and the like, and can be used for security inspection and counter terrorism; the terahertz wave has a shorter wavelength than the millimeter wave, and can obtain better imaging resolution when used for imaging. Terahertz waves generated based on a femtosecond laser have time resolution capability and broadband characteristics, so terahertz spectrum and imaging technology built based on the terahertz waves generated by the femtosecond laser have rapidly developed in various fields such as physics, chemistry, materials, biology, medicine and the like.
The terahertz imaging technology has important application in the field of terahertz science and technology, and is the most regarded research field. The earliest terahertz imaging is used for researching the water content of leaves, metal cutters and weapons hidden under clothes and the like, and the penetrating capability of terahertz waves is fully utilized. The modern terahertz imaging technology is not only applied to the aspect of safety inspection, but also has a huge application prospect in the aspect of medical imaging. For example, terahertz imaging difference of water content of tumor tissue and normal tissue can be compared to identify the tumor tissue; by utilizing the non-contact detection and penetration capability of the terahertz waves, the terahertz imaging technology also occupies a place in the oil painting identification aspect. Because the drawing process of the oil painting is a layer-by-layer manufacturing process, the effect of the last layer is finally presented in front of people, and the contents such as the previous foundation of an author and the conception of the bottom layer cannot be presented in front of the eyes of a viewer. By utilizing the penetrating capability of the terahertz waves with different wavelengths, the original appearance of each layer of oil painting can be reproduced, and the thought of the author for painting can be known. The terahertz imaging technology and the compressed sensing technology can realize single-pixel terahertz imaging, so that the application field of the terahertz imaging technology is greatly improved. Of course, there is a great potential for the application of terahertz imaging techniques, far from the ones listed above.
With the progress of science and technology, the power of terahertz radiation obtained based on femtosecond laser technology frequency down-conversion, quantum cascade technology and vacuum electronics at present reaches milliwatt level and even kilowatt level. For the appearance of such high-energy terahertz radiation sources, the demand for terahertz energy detectors has increased sharply, and among them, the optical rectification effect represented by the femtosecond laser technology generates the high-energy terahertz radiation technology, and the laser plasma generates the terahertz radiation technology, which is the best method for obtaining the terahertz radiation source with high peak power, ultrashort pulses, and time resolution capability in a laboratory. The technology for generating terahertz radiation based on the femtosecond laser optical rectification effect is divided into a nonlinear organic crystal and an inclined wavefront technology based on lithium niobate. Terahertz waves with radiation energy greater than 0.9mJ have been obtained by the nonlinear organic crystal-based terahertz radiation technology, and terahertz waves with radiation energy greater than 0.4mJ have also been obtained by the lithium niobate-based oblique wavefront technology terahertz radiation source. The plasma terahertz radiation source based on the femtosecond laser can obtain terahertz waves with radiation energy of more than 1mJ magnitude, and the plasma terahertz radiation source based on the laser bicolor field induction can also obtain terahertz waves with radiation energy of more than 5 muJ. The terahertz radiation source with high energy can directly adopt the terahertz camera to detect terahertz waves. With the further development of high-energy high-field terahertz radiation sources, a terahertz camera with low cost is greatly required.
The traditional terahertz imaging method is to scan an object to be imaged in a terahertz time-domain spectrometer and obtain images of different frequencies by measuring the transmission intensity and phase change of each point of the object to be imaged. Commercial terahertz cameras are primarily pyroelectric-based detector array cameras. For cameras with frequencies above 1THz, only the 1-7THz band is operated. For a terahertz source generated by an inclined wavefront technology, the center frequency is below 0.5THz, and a terahertz camera used in cooperation is large in size, high in price, complex in experimental operation and low in refreshing frequency. Therefore, the array terahertz camera with low cost, high integration and large area has great application prospect.
Terahertz imaging is mainly classified into a scanning type indirect terahertz imaging technique and a direct terahertz imaging technique using a camera. The scanning type indirect terahertz imaging technology is mainly based on a terahertz time-domain spectrometer. The terahertz image recovery device has the main working principle that an object to be imaged is placed at a light spot focused by terahertz waves in a terahertz spectrograph, terahertz transmission signals of all pixel points on the object to be imaged are measured and correspondingly recorded, then the object to be imaged is scanned point by point, and finally, terahertz images of the object to be imaged are recovered through data processing. The terahertz imaging technology of point-by-point scanning can be divided into two types because of the category of terahertz spectrometers, one is a time domain technology, and the other is a frequency domain technology. The time-domain imaging technology is to use a coherent detection mode in a terahertz time-domain spectrometer to detect the amplitude and phase information of each pixel point on an object to be imaged, so as to construct a terahertz image of the object to be imaged. Although the terahertz radiation source generated by the femtosecond laser acting on the nonlinear optical crystal or the photoconductive antenna acts on the object to be imaged to form a broadband terahertz radiation source, the obtained terahertz image can extract information with different frequencies to obtain phase information corresponding to different material depths, the point-by-point scanning imaging mode is limited by the working speed of terahertz time-domain spectroscopy, the imaging speed is very low, and the terahertz radiation source cannot be applied to actual imaging, such as security inspection imaging and medical imaging. The other imaging system based on the terahertz frequency domain spectroscopy system is similar to the terahertz frequency domain spectroscopy system, and a point-by-point scanning mode is also adopted. The terahertz radiation source generally adopts two semiconductor lasers to obtain single-frequency terahertz emission in a beat frequency generation mode, and then a detection signal of the single-frequency terahertz radiation is realized through a photoconductive antenna. An object to be imaged is placed at a light spot focused by the terahertz, and a scanning translation table for mounting the object is moved by fixing the transmitting frequency of the transmitter, so that a terahertz image with a single frequency can be obtained. The terahertz image of the object to be imaged is obtained in a point-by-point scanning mode, and the defects of low imaging speed, long time consumption and the like exist as in the time-domain terahertz scanning imaging technology.
The terahertz camera adopts a direct imaging mode for an object to be imaged, and overcomes the defects caused by scanning imaging. However, the existing terahertz camera is extremely expensive in manufacturing cost, large in size, limited in light sensing area and limited in response speed by the detection principle. Therefore, it is urgently needed to provide a terahertz camera with low cost, small volume and adjustable photosensitive area.
Disclosure of Invention
Therefore, an object of the present invention is to overcome the defects in the prior art, and provide a terahertz camera, a terahertz imaging system and an application thereof.
Before setting forth the context of the present invention, the terms used herein are defined as follows:
the term "P-N junction" refers to: different doping processes are adopted, a P-type semiconductor and an N-type semiconductor are manufactured on the same semiconductor substrate through diffusion, and a space charge region formed at the interface of the P-type semiconductor and the N-type semiconductor is called a P-N junction.
To achieve the above object, a first aspect of the present invention provides a terahertz camera, including: a P-N junction cell array and a processing module;
the P-N junction unit array comprises a plurality of P-N junction units, and the processing module is electrically connected with each P-N junction unit; the P-N junction unit array is used for converting received terahertz waves into voltage signals, and the processing module is used for determining the light spot profile of the terahertz waves according to the voltage signals;
preferably, the number of the P-N junction units is 4 or more, preferably 16 or more, and more preferably 100 or more.
The terahertz camera according to the first aspect of the present invention, wherein the P-N junction unit is: light emitting diodes, silicon based diodes; preferably a light emitting diode;
more preferably, the light emitting diode is prepared by the following method:
and curing the semiconductor material chip on the bracket, connecting the chip and the circuit board by using a conducting wire, and sealing the periphery by using epoxy resin to obtain the light-emitting diode.
The terahertz camera according to the first aspect of the present invention, wherein the terahertz camera further comprises: a display module;
the display module is electrically connected with the processing module and is used for displaying the light spot profile of the terahertz waves.
The terahertz camera according to the first aspect of the present invention, wherein the processing module specifically includes a plurality of processing sub-modules, the plurality of processing sub-modules correspond to and are electrically connected to the plurality of P-N junction units one to one,
the voltage signals respectively comprise a plurality of sub-voltage signals, and the sub-voltage signals correspond to the P-N junction units one by one;
preferably, each P-N junction unit is configured to receive a part of the terahertz waves and convert the received part of the terahertz waves into corresponding sub-voltage signals; and/or
Each processing sub-module is used for determining the intensity distribution of part of terahertz waves received by the corresponding P-N junction unit according to the sub-voltage signals obtained by conversion of the corresponding P-N junction unit.
A second aspect of the present invention provides a terahertz imaging system, including: a terahertz camera, a femtosecond laser, and a preset sample as described in the first aspect;
the terahertz imaging system according to the second aspect of the present invention, wherein the terahertz wave is generated by irradiating the preset sample with the pump laser generated by the femtosecond laser.
The predetermined sample is selected from one or more of: organic crystals, lithium niobate crystals, plasma;
preferably, the preset sample is lithium niobate crystal.
The terahertz imaging system according to the second aspect of the present invention, wherein the imaging system further comprises: a focusing module;
the focusing module is arranged between the preset sample and the P-N junction unit array, and the object to be imaged is arranged between the focusing module and the P-N junction unit array;
the focusing module is used for focusing the terahertz waves on the object to be imaged.
Preferably, the focusing module includes: a focusing lens or a parabolic mirror.
A third aspect of the invention provides a method of using the terahertz imaging system of the second aspect, the method comprising the steps of:
(1) arranging the object to be imaged between the preset sample and the P-N junction unit array;
(2) and after the terahertz waves pass through the object to be imaged, the terahertz waves are received by the P-N junction unit array, and the image of the object to be imaged is determined through the processing module.
A fourth aspect of the present invention provides a terahertz imaging method using the terahertz camera according to the first aspect or the terahertz imaging system according to the second aspect.
To overcome the above problems or at least partially solve the above problems, embodiments of the present invention provide a terahertz camera and a terahertz imaging system.
The embodiment of the invention provides a terahertz camera, which comprises: a P-N junction cell array and a processing module;
the P-N junction unit array comprises a plurality of P-N junction units, and the processing module is electrically connected with each P-N junction unit; the P-N junction unit array is used for converting received terahertz waves into voltage signals, and the processing module is used for determining the light spot profile of the terahertz waves according to the voltage signals.
The embodiment of the invention provides a terahertz imaging system, which comprises: the terahertz camera according to the first aspect, further comprising: a femtosecond laser and a preset sample;
the terahertz wave is generated by irradiating the preset sample with pumping laser generated by the femtosecond laser.
According to the terahertz camera provided by the embodiment of the invention, the P-N junction unit array is used as a receiver for receiving terahertz waves, so that the terahertz waves are imaged. According to the embodiment of the invention, the P-N junction unit array is adopted to construct the terahertz camera, the terahertz camera is not limited by temperature and surrounding environment, the imaging speed is high, the size is small, the operation is simple, the cost is low, the P-N junction unit has high detection sensitivity to terahertz waves, even if weak terahertz waves are focused, high-quality focused light spots can be obtained on the P-N junction unit array, and further the imaging of an object to be imaged is clearer.
Specifically, the P-N junction unit in the embodiment of the present invention is a device capable of converting terahertz waves into voltage signals, and a P-N junction unit array integrated with a plurality of P-N junction units is used as a receiver for receiving terahertz waves, so as to realize imaging of terahertz waves, and thus obtain a light spot profile of terahertz waves. It will be appreciated that this is actually imaging each P-N junction cell as one pixel cell of the terahertz camera.
Specifically, in the terahertz camera provided in the embodiment of the present invention, the processing module specifically includes a plurality of processing sub-modules, and each processing sub-module corresponds to and is electrically connected to one P-N junction unit. The processing sub-module is used for determining the intensity distribution of part of the terahertz waves at the position of the corresponding P-N junction unit according to the sub-voltage signals obtained by converting the corresponding P-N junction unit.
In the terahertz imaging system provided by the embodiment of the invention, the cost of the P-N junction unit serving as the pixel unit of the terahertz camera is very low, compared with the existing terahertz camera, the cost is only one hundred thousandth of the existing terahertz camera, and the cost is greatly reduced.
Specifically, in the embodiment of the present invention, only three preset samples capable of outputting terahertz waves through irradiation of pump laser light are listed, but the present invention is not limited thereto, and any preset sample may be used as long as terahertz waves can be generated through irradiation of pump laser light.
The terahertz camera of the invention can have the following beneficial effects:
1) the cost is low: the cost of the P-N junction unit for the pixel unit of the terahertz camera is very low, and compared with the existing terahertz camera, the cost is only one hundred thousand of the existing terahertz camera.
2) The pixel unit area can be smaller, the imaging resolution is improved: the process technology based on the P-N junction unit is mature, so that the area of a single pixel unit (namely the P-N junction unit and the light emitting diode) of the terahertz camera can be made small, and the imaging resolution of the terahertz camera can be greatly improved.
3) The imaging sensitivity is high: the chip of a single pixel point of the terahertz camera is manufactured by selecting the P-N junction unit with high response sensitivity, so that very high detection sensitivity can be obtained, imaging can be realized even if very weak terahertz wave light spots and an object to be imaged, and light spot profiles and images of the object to be imaged are obtained.
4) The response speed is high: the terahertz camera provided by the embodiment of the invention adopts the P-N junction unit as the pixel unit, does not relate to a thermal response process, but has the direct response speed of electrons, so that the response speed is very high.
5) Video real-time imaging: the terahertz camera provided by the embodiment of the invention does not need to scan and image an object to be imaged, so that real-time imaging can be realized, and the terahertz camera is equivalent to a terahertz video recorder.
6) The P-N junction unit is small in size, easy to package, free of additional driving voltage and convenient to operate in actual light path operation and application.
Drawings
Embodiments of the invention are described in detail below with reference to the attached drawing figures, wherein:
fig. 1 shows a schematic structural diagram of a terahertz camera provided by an embodiment of the present invention;
fig. 2 shows a schematic structural diagram of a terahertz imaging system provided by an embodiment of the present invention;
fig. 3 shows a schematic structural diagram of a terahertz imaging system provided by an embodiment of the invention.
Reference numerals:
1. a P-N junction cell array; 2. a processing module; 3. a femtosecond laser; 4. presetting a sample; 5. an object to be imaged; 11. a P-N junction unit.
Detailed Description
The invention is further illustrated by the following specific examples, which, however, are to be construed as merely illustrative, and not limitative of the remainder of the disclosure in any way whatsoever.
This section generally describes the materials used in the testing of the present invention, as well as the testing methods. Although many materials and methods of operation are known in the art for the purpose of carrying out the invention, the invention is nevertheless described herein in as detail as possible. It will be apparent to those skilled in the art that the materials and methods of operation used in the present invention are well within the skill of the art, provided that they are not specifically illustrated.
In the description of the embodiments of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience in describing the embodiments of the present invention and simplifying the description, but do not indicate or imply that the referred devices or elements must have specific orientations, be configured in specific orientations, and operate, and thus, should not be construed as limiting the embodiments of the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the embodiments of the present invention, it should be noted that, unless explicitly stated or limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. Specific meanings of the above terms in the embodiments of the present invention can be understood in specific cases by those of ordinary skill in the art.
The apparatus used in the following examples is as follows:
the instrument comprises the following steps:
femtosecond laser, available from Amplite Technologies, France, model number Pulsar 20.
Example 1
This embodiment is used to explain the structure of the terahertz camera of the present invention.
As shown in fig. 1, the present invention provides a terahertz camera, including: a P-N junction unit array 1 and a processing module 2;
the P-N junction unit array 1 includes a plurality of P-N junction units 11, in fig. 1, the processing module 2 is electrically connected to the P-N junction unit array 1, and the processing module 2 is specifically and respectively electrically connected to each P-N junction unit 11;
the P-N junction unit array 1 is used for converting received terahertz waves into voltage signals, and the processing module 2 is used for determining the light spot profile of the terahertz waves according to the voltage signals.
Specifically, the P-N junction unit in the embodiment of the present invention is a device capable of converting terahertz waves into voltage signals, and a P-N junction unit array integrated with a plurality of P-N junction units is used as a receiver for receiving terahertz waves, so as to realize imaging of terahertz waves, and thus obtain a light spot profile of terahertz waves. It will be appreciated that this is actually imaging each P-N junction cell as one pixel cell of the terahertz camera.
The terahertz camera can accommodate 256P-N junction units under enough space size.
When the terahertz waves irradiate on the P-N junction unit array, the P-N junction unit array can convert the received terahertz waves into voltage signals. The intensity of the voltage signal obtained by the P-N junction unit array can directly represent the energy of the terahertz wave (namely the intensity of the terahertz wave), and because the light spot of the terahertz wave generally has a certain size and certain energy distribution, at different positions of the light spot, the intensity of the voltage signal obtained from the P-N junction unit array can directly determine the energy of the terahertz wave at different positions due to different energy. Therefore, the processing module can determine an image representing the energy distribution of the terahertz wave, namely a light spot profile of the terahertz wave according to the strength of the voltage signal, and it can be understood that the light spot profile is an energy distribution diagram of the terahertz wave.
Examples2
This embodiment is used to explain the structure of the terahertz camera of the present invention.
On the basis of embodiment 1, the terahertz camera provided in this embodiment further includes a display module; the display module is electrically connected with the processing module and is used for displaying the light spot profile of the terahertz waves. The display module adopted in the embodiment is a computer display. The display module is used for displaying the light spot profile of the terahertz wave, namely, the light spot profile of the terahertz wave determined by the processing module is subjected to imaging display.
Example 3
This embodiment is used to explain the structure of the processing module in the terahertz camera of the present invention.
The terahertz camera processing module provided by the embodiment of the invention specifically comprises a plurality of processing sub-modules, wherein the plurality of processing sub-modules correspond to the plurality of P-N junction units one by one and are electrically connected with the plurality of P-N junction units;
correspondingly, the voltage signal comprises a plurality of sub-voltage signals, and the plurality of sub-voltage signals correspond to the plurality of P-N junction units one to one;
each P-N junction unit is used for receiving part of the terahertz waves in the terahertz waves and converting the received part of the terahertz waves into corresponding sub-voltage signals;
each processing sub-module is used for determining the intensity distribution of part of terahertz waves received by the corresponding P-N junction unit according to the sub-voltage signals obtained by conversion of the corresponding P-N junction unit.
The intensity of the voltage signal can directly represent the energy of part of the terahertz wave corresponding to the position of the P-N junction unit, so that the voltage signal corresponding to each position on the light spot is obtained, and the intensity distribution corresponding to the light spot can be determined according to the voltage signal, namely the intensity distribution of the terahertz wave light spot is obtained through the intensity distribution of the voltage signal.
The partial terahertz wave is a part of the whole terahertz wave corresponding to the position of each P-N junction unit.
Example 4
This embodiment is used to illustrate the structure of the P-N junction unit in the terahertz camera of the present invention.
Preferably, in the embodiment of the present invention, a Light Emitting Diode (LED) is used as the P-N junction unit. The light emitting diode adopted in the embodiment of the invention is a semiconductor material chip, silver glue or white glue is used for solidifying the chip on the bracket, then silver wires or gold wires are used for connecting the chip and the circuit board, and the periphery of the chip is sealed by epoxy resin, so that the function of protecting the internal core wires is achieved.
In the embodiment of the invention, the detection capability of the high-energy terahertz wave can be realized by using the light-emitting diode, and the terahertz light spot and the object to be imaged can be imaged by using the mature material processing and circuit integration process of the light-emitting diode and by reducing the chip of the light-emitting diode to realize integration. The size of a light spot of the terahertz wave is in millimeter order, so that the size of a chip of the light emitting diode determines the pixel and the imaging resolution of the terahertz camera. The lateral size of a common direct-insertion normally-installed LED chip is hundreds of microns, the LED chip can be modified according to actual requirements, and the ultraviolet lithography technology can reach several microns at most. Because the light-emitting diode has high detection sensitivity to the terahertz waves, even if weak terahertz wave light spots are focused, the light spot profile of the terahertz waves with high quality can be obtained on a terahertz camera formed by the light-emitting diode, and the imaging of an object to be imaged is clearer.
Example 5
This embodiment is used to explain the structure of the terahertz imaging system of the present invention.
On the basis of the above embodiments, the present embodiment provides a terahertz imaging system, including: the terahertz camera in each embodiment above further includes: a femtosecond laser and a preset sample;
the terahertz waves are generated by irradiating the preset sample with pumping laser generated by the femtosecond laser.
Specifically, as shown in fig. 2, the present embodiment provides a terahertz imaging system, in fig. 2, a pump laser generated by a femtosecond laser 3 irradiates a predetermined sample 4 to generate a terahertz wave, the terahertz wave irradiates a P-N junction unit array 1, and a spot profile of the terahertz wave is obtained after the terahertz wave passes through a processing module 2.
The presetting of the sample specifically comprises: organic crystal (DAST, DSTMS, OH1), lithium niobate crystal or air or metal plasma, the choice of the metal target adopted in the terahertz generated by laser plasma has no obvious difference to the generated THz energy, the copper target is generally the best, and the energy of other metal target materials is only about twenty percent difference compared with the copper target. As shown in fig. 3, on the basis of the above embodiment, when the terahertz imaging system is applied to image an object to be imaged, the object to be imaged 5 is arranged between the preset sample 4 and the P-N junction unit array 1; after the terahertz waves pass through an object to be imaged 5, the terahertz waves are received by the P-N junction unit array 1, and an image of the object to be imaged is determined through the processing module 2.
The working principle of the terahertz imaging system is that a P-N junction unit array is used as an integrated array type pixel point, different responses of each pixel point to terahertz power are output in an electric signal mode, and the electric signal is analyzed, so that a light spot profile of terahertz waves is restored. Then, an object to be imaged is directly inserted into the optical path, and an image of the object appears on the terahertz camera because the object to be imaged blocks part of the energy of the terahertz wave in space. The terahertz camera is simple and intuitive, can be used for high-power single-frequency terahertz waves generated by a quantum cascade laser, and can also be used for high-energy terahertz waves generated by a femtosecond laser.
The terahertz imaging system provided by the embodiment of the invention can also image an object to be imaged, and at the moment, the object to be imaged only needs to be arranged between the preset sample and the P-N junction unit array, namely, the object to be imaged is arranged on the transmission path of the terahertz waves. The terahertz imaging system provided by the embodiment of the invention adopts the P-N junction unit array as the receiver of the terahertz wave, and scanning imaging is not required to be carried out on an object to be imaged, so that real-time imaging can be realized, and the terahertz imaging system is equivalent to a terahertz video recorder.
The P-N junction unit array can be integrated in a large area, and for a terahertz radiation source with higher energy, a terahertz wave focusing system is not needed, and the light spot profile of the terahertz wave can be detected directly on a collimation light path or a place close to the terahertz wave. An object to be imaged can also be directly placed between the transmission path of the terahertz waves and the terahertz camera, so that a terahertz image of the object to be imaged is obtained on the terahertz camera.
Example 6
This embodiment is used to explain the structure of the terahertz imaging system of the present invention.
On the basis of the above embodiments, an embodiment of the present invention provides a terahertz imaging system, further including: a focusing module; the focusing module is arranged between the preset sample and the P-N junction unit array, and the object to be imaged is arranged between the focusing module and the P-N junction unit array;
the focusing module is used for focusing the terahertz waves on the object to be imaged.
Specifically, in the embodiment of the invention, the terahertz imaging system is provided with the focusing module, so as to ensure that terahertz waves generated by a preset sample can be accurately focused on the P-N junction unit array.
As a preferred scheme, the focusing module provided in the embodiment of the present invention specifically includes: a focusing lens or a parabolic mirror.
Test example 1
This test example is for explaining the effect of the terahertz camera of the present invention.
According to the resolution limit of the ultraviolet lithography technology, the terahertz camera can achieve 10-micron spatial resolution, and the sensitivity can reach 1250V/W at most by directly measuring open-circuit voltage in a measuring mode without adding an external amplifier.
The above-described embodiments of the apparatus are merely illustrative, and the units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware. With this understanding in mind, the above-described technical solutions may be embodied in the form of a software product, which can be stored in a computer-readable storage medium such as ROM/RAM, magnetic disk, optical disk, etc., and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the methods described in the embodiments or some parts of the embodiments.
Although the present invention has been described to a certain extent, it is apparent that appropriate changes in the respective conditions may be made without departing from the spirit and scope of the present invention. It is to be understood that the invention is not limited to the described embodiments, but is to be accorded the scope consistent with the claims, including equivalents of each element described.
Claims (15)
1. A terahertz camera, characterized in that the terahertz camera comprises: a P-N junction cell array and a processing module, wherein:
the P-N junction unit array comprises a plurality of P-N junction units, and the processing module is electrically connected with each P-N junction unit; the P-N junction unit array is used for converting received terahertz waves into voltage signals, and the processing module is used for determining the light spot profile of the terahertz waves according to the voltage signals;
the P-N junction unit is a light emitting diode.
2. The terahertz camera of claim 1, wherein the number of the P-N junction units is 4 or more.
3. The terahertz camera of claim 2, wherein the number of the P-N junction units is 16 or more.
4. The terahertz camera of claim 3, wherein the number of the P-N junction units is more than 100.
5. The terahertz camera of claim 1, wherein the light emitting diode is prepared by:
and curing the semiconductor material chip on the bracket, connecting the chip and the circuit board by using a conducting wire, and sealing the periphery by using epoxy resin to obtain the light-emitting diode.
6. The terahertz camera of claim 1, further comprising: a display module;
the display module is electrically connected with the processing module and is used for displaying the light spot profile of the terahertz waves.
7. The terahertz camera of claim 1, wherein:
the processing module comprises a plurality of processing sub-modules which are in one-to-one correspondence with and electrically connected with the plurality of P-N junction units,
the voltage signals respectively comprise a plurality of sub-voltage signals, and the sub-voltage signals correspond to the P-N junction units one to one.
8. The terahertz camera of claim 7, wherein each P-N junction unit is configured to receive a portion of the terahertz waves and convert the received portion of the terahertz waves into corresponding sub-voltage signals; and/or
Each processing sub-module is used for determining the intensity distribution of part of terahertz waves received by the corresponding P-N junction unit according to the sub-voltage signals obtained by conversion of the corresponding P-N junction unit.
9. A terahertz imaging system, comprising: the terahertz camera, the femtosecond laser, and the preset sample as set forth in any one of claims 1 to 8;
wherein the terahertz wave is generated by irradiating the preset sample with pumping laser light generated by the femtosecond laser.
10. The terahertz imaging system of claim 9, wherein the predetermined sample is selected from one or more of: organic crystals, lithium niobate crystals, plasma.
11. The terahertz imaging system of claim 10, wherein the predetermined sample is a lithium niobate crystal.
12. The terahertz imaging system of claim 9, further comprising: a focusing module;
the focusing module is arranged between the preset sample and the P-N junction unit array, and an object to be imaged is arranged between the focusing module and the P-N junction unit array;
the focusing module is used for focusing the terahertz waves on the object to be imaged.
13. The terahertz imaging system of claim 12, wherein the focusing module comprises: a focusing lens or a parabolic mirror.
14. Use of the terahertz imaging system according to any one of claims 9 to 13, the method comprising the steps of:
(1) arranging an object to be imaged between the preset sample and the P-N junction unit array;
(2) and after the terahertz waves pass through the object to be imaged, the terahertz waves are received by the P-N junction unit array, and the image of the object to be imaged is determined through the processing module.
15. A terahertz imaging method, characterized in that the method uses the terahertz camera of any one of claims 1 to 8 or the terahertz imaging system of any one of claims 9 to 13.
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