A terahertz single-pixel imaging device encoded by atomic fluorescence

Abstract

The present application relates to the technical field of terahertz imaging, and specifically discloses an atomic fluorescence coded terahertz single-pixel imaging device, which comprises a laser space modulation module, an atomic fluorescence coding module and an acquisition and processing module; the laser space modulation module comprises a coupling light laser, a Rydberg light laser, a laser shaping module and a probe light coding module; the probe light coding module comprises a probe light laser, a digital microscopic array and a first plano-convex lens; the atomic fluorescence coding module comprises an atomic gas chamber and a terahertz source; the atomic fluorescence coded terahertz single-pixel imaging device can realize level transition de-excitation radiation fluorescence, and can simultaneously code and convert terahertz into visible light, and then acquire and process the image to realize an encoding speed of MHz, improve the speed of single-pixel imaging, and have a wide application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of terahertz imaging, in particular to an atomic fluorescence coded terahertz single-pixel imaging device. BACKGROUND

[0002] Terahertz waves refer to electromagnetic waves with a frequency range of 0.1-10 THz (wavelength 30 um-3 mm). It can penetrate most dielectric materials and non-polar liquids, and has great imaging potential because it is harmless to human tissue. The present disclosure aims to provide a terahertz imaging device that can convert terahertz into visible light while encoding, achieve an encoding speed of MHz, improve the speed of single-pixel imaging, and meet the use requirements of the market. SUMMARY

[0003] The technical problem to be solved by the present application is to provide an atomic fluorescence coded terahertz single-pixel imaging device that can convert terahertz into visible light, then collect and process to obtain an image, has a fast imaging speed, and has a wide application prospect.

[0004] To solve the above problems, the present application adopts the following technical scheme:

[0005] An atomic fluorescence coded terahertz single-pixel imaging device, comprising a laser spatial modulation module, an atomic fluorescence coding module, and a collection and processing module.

[0006] The laser spatial modulation module comprises a coupling light laser, a Rydberg light laser, a laser shaping module, and a probe light coding module.

[0007] The probe light coding module comprises a probe light laser, a digital microscopic array, and a first plano-convex lens.

[0008] The atomic fluorescence coding module comprises an atomic gas chamber and a terahertz source.

[0009] The laser shaping module is used to shape the laser spots emitted by the coupling light laser and the Rydberg light laser into light sheets, respectively, and combine the two shaped lasers into a beam that is injected into the atomic gas chamber.

[0010] The first plano-convex lens is used to expand the beam of the probe light emitted by the probe light laser, so that the spot area of the probe light is larger than the modulation area of the digital microscopic array.

[0011] The digital microscopic array is used to spatially modulate the probe light and vertically inject it into the atomic gas chamber, so that the probe light obtains spatial structure information before entering the atomic gas chamber.

[0012] The atomic gas chamber is used to provide a terahertz wave coding area.

[0013] The terahertz source is used to emit terahertz waves that envelop the entire atomic gas chamber, so that the atoms in the overlapping area of ​​the three laser beams in the atomic gas chamber will be further coupled and excited to a higher Rydberg state by the terahertz waves and de-excited to emit green fluorescence, thereby transforming the spatial information of the encoded probe light into the spatial encoding of the terahertz waves, and at the same time converting the terahertz waves into visible light signals.

[0014] The acquisition and processing module is used to receive visible light signals and convert the received visible light signals into electrical signals.

[0015] The acquisition and processing module is also used to obtain the intensity information of visible light based on the voltage of the electrical signal, and to obtain the correlation measurement results of the imaging target.

[0016] In at least one embodiment of the atomic fluorescence encoded terahertz single-pixel imaging device provided in this disclosure, the laser shaping module includes a first shaping lens group, a second shaping lens group, and a dichroic mirror.

[0017] The optical path of the first shaping lens group is perpendicular to the optical path of the second shaping lens group.

[0018] Both the first shaping lens group and the second shaping lens group are used to shape the laser spot into a sheet shape.

[0019] In at least one embodiment of the atomic fluorescence encoded terahertz single-pixel imaging device provided in this disclosure, the acquisition and processing module includes a visible light lens and a photodetector.

[0020] The visible light lens is used to focus visible light onto the signal receiving port of the photodetector so that the photodetector can receive all the visible light signals.

[0021] In at least one embodiment of the atomic fluorescence encoded terahertz single-pixel imaging device provided in this disclosure, the wavelength of the probe light is 852 nm.

[0022] In at least one embodiment of the atomic fluorescence encoded terahertz single-pixel imaging device provided in this disclosure, the wavelength of the coupled light emitted by the coupled laser is 1470 nm.

[0023] In at least one embodiment of the atomic fluorescence encoded terahertz single-pixel imaging device provided in this disclosure, the Rydberg laser emits Rydberg light with a wavelength of 843 nm.

[0024] In at least one embodiment of the atomic fluorescence encoded terahertz single-pixel imaging device provided in this disclosure, both the first shaping lens group and the second shaping lens group include a second plano-convex lens and a cylindrical lens.

[0025] The beneficial effects of this invention are as follows: the terahertz wave carrying spatial coding information during the Rydberg atomic energy level transition will be converted into a fluorescence field generated by its de-excitation radiation. The fluorescence field can be modulated by modulating the probe light.

[0026] Based on the single-pixel imaging method, an image of the target object can be reconstructed by measuring the associated fluorescence field intensity. Because Rydberg atoms have a large electric dipole moment and are sensitive to external fields, a coding speed of MHz can be achieved, resulting in high-sensitivity, high-signal-to-noise ratio, and fast imaging results. Furthermore, the device is compatible with compressed sensing methods, which can reduce imaging time and improve imaging efficiency. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the structure of an atomic fluorescence encoded terahertz single-pixel imaging device according to the present invention.

[0029] In the picture:

[0030] 10. Coupled-beam laser; 11. Rydberg laser; 12. Probe laser; 13. Digital microscope array; 14. First plano-convex lens; 15. First shaping lens group; 16. Second shaping lens group; 17. Dichroic mirror;

[0031] 20. Atomic gas chamber; 21. Terahertz source;

[0032] 30. Visible light lens; 31. Photodetector. Detailed Implementation

[0033] The technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments, not all embodiments.

[0034] Example

[0035] like Figure 1 As shown, an atomic fluorescence encoded terahertz single-pixel imaging device includes a laser spatial modulation module, an atomic fluorescence encoding module, and an acquisition and processing module.

[0036] The laser spatial modulation module includes a coupled optical laser 10, a Rydberg optical laser 11, a laser shaping module, and a probe optical encoding module.

[0037] The probe light encoding module includes a probe light laser 12, a digital microarray 13, and a first plano-convex lens 14.

[0038] The atomic fluorescence encoding module includes an atomic gas cell 20 and a terahertz source 21.

[0039] Specifically, the laser shaping module is used to shape the laser spots emitted by the coupled laser 10 and the Rydberg laser 11 into light sheets, and then combine the shaped laser beams into the atomic gas chamber 20.

[0040] Specifically, the first plano-convex lens 14 is used to expand the probe light emitted by the probe laser 12, so that the spot area of ​​the probe light is larger than the modulation area of ​​the digital microscope array 13. The first plano-convex lens 14 is located between the probe laser 12 and the digital microscope array 13.

[0041] Specifically, the digital microscope array 13 is used to spatially modulate the probe light and vertically penetrate it into the atomic gas chamber 20, so that the probe light can obtain spatial structure information before entering the atomic gas chamber 20.

[0042] Specifically, the atomic gas chamber 20 is used to provide a terahertz wave encoding region. The terahertz source 21 is used to emit terahertz waves that cover the entire atomic gas chamber 20, so that the atoms in the overlapping region of the three laser beams in the atomic gas chamber 20 will be further coupled and excited to a higher Rydberg state by the terahertz waves and de-excited to emit green fluorescence, thereby transforming the spatial information of the encoded probe light into the spatial encoding of the terahertz wave, and at the same time converting the terahertz wave into a visible light signal.

[0043] Specifically, the acquisition and processing module receives visible light signals and converts them into electrical signals. The module also obtains the intensity information of the visible light based on the voltage of the electrical signal, thus acquiring the correlation measurement results of the imaging target.

[0044] In this embodiment, the laser shaping module includes a first shaping lens group 15, a second shaping lens group 16, and a dichroic mirror 17.

[0045] Specifically, the optical paths of the first shaping lens group 15 and the second shaping lens group 16 are perpendicularly distributed.

[0046] Specifically, the first shaping lens group 15 and the second shaping lens group 16 are used to shape the laser spots of the coupled laser 10 and the Rydberg laser 11 into light sheet shapes, respectively.

[0047] Specifically, both the first shaping lens group 15 and the second shaping lens group 16 include a second plano-convex lens and a cylindrical lens.

[0048] Furthermore, the cylindrical lens is located in front of the second plano-convex lens, and the second plano-convex lens is located behind the dichroic mirror 17. The cylindrical lens, the second plano-convex lens, and the dichroic mirror 17 are arranged sequentially along the optical path.

[0049] In this embodiment, the acquisition and processing module includes a visible light lens 30 and a photodetector 31.

[0050] Specifically, the visible light lens 30 is used to focus visible light onto the signal receiving port of the photodetector 31, so that the photodetector 31 can receive all the visible light signals. The visible light lens 30 is located between the photodetector 31 and the atomic gas chamber 20.

[0051] In this embodiment, the wavelength of the probe light is 852 nm. The wavelength of the coupled light emitted by the coupled laser 10 is 1470 nm. The wavelength of the Rydberg light emitted by the Rydberg laser 11 is 843 nm.

[0052] For example, the coupled light laser 10, the Rydberg light laser 11, and the probe light laser 12 are all semiconductor lasers.

[0053] The working principle of the atomic fluorescence encoded terahertz single-pixel imaging device in the embodiments will be disclosed below.

[0054] The coupled laser outputs coupled light with a wavelength of 1470nm, and the Rydberg laser outputs Rydberg light with a wavelength of 843nm. The two laser beams are shaped into light sheets by their respective cylindrical lenses and second plano-convex lenses, and then combined by dichroic mirrors to hit the atomic gas chamber.

[0055] The probe laser outputs an 852nm probe beam, which is expanded by a first plano-convex lens and strikes the surface of a digital microarray. The digital microarray modulates the beam to obtain structured light with spatial information, which is then reflected into the atomic gas chamber. The atoms within the atomic gas chamber are excited step-by-step by these three laser beams, eventually reaching a Rydberg state. This state is then coupled with a terahertz wave emitted from a terahertz source, exciting the atoms to an even higher Rydberg state and causing them to de-excite and emit fluorescence with the same encoded information as the probe beam.

[0056] The spatial information of the probe light to be encoded is converted into spatial encoding of terahertz waves, and at the same time, the terahertz waves are converted into visible light. The fluorescent light is then focused by a visible light lens and received by a photodetector.

[0057] Based on the principle of single-pixel imaging, the measurement result can be expressed as:

[0058]

[0059] Where row and col represent the row and column numbers of the mask unit (pixel in the image matrix), respectively. If the matrix and O m Rearrange the vectors into rows (or columns) of length N (N = L × L). and O m Therefore, the above equation can be more conveniently expressed as the inner product of these two vectors:

[0060]

[0061] Where j represents the position of the element in the vector; in the i-th correlation measurement, a mask unit of size L×L is used. Spatially modulate the THz wave to obtain a THz wave with a coded structure corresponding to the spatial distribution, and finally determine its intensity y. i It is detected and recorded by the detector.

[0062] Now consider N linearly independent mask vectors. Stacking these columns together to form an N*N square matrix, called the observation matrix M, allows us to represent the complete correlation measurement process for the imaging target as follows:

[0063]

[0064] Where Y is a column vector composed of associated measurements, and its length is N.

[0065] Since all N mask vectors are linearly independent, the observation matrix M must have an inverse matrix M. -1 Then the target image can be reconstructed according to the following formula:

[0066] X = M -1 Y = M -1 MO = 0;

[0067] In summary, this disclosure provides an effective method for encoding terahertz waves. During encoding, terahertz waves can be converted into visible light, achieving an encoding speed of MHz. Based on the single-pixel imaging principle, the image can be recovered by acquiring and processing visible light information.

[0068] Although embodiments of this application have been shown and described above, the scope of protection of this invention is not limited thereto. Any variations or substitutions that can be conceived without inventive effort should be covered within the scope of protection of this invention. Unless expressly stated otherwise, no element, action or instruction used herein should be construed as critical or necessary.

Claims

1. An atomic fluorescence encoded terahertz single-pixel imaging device, characterized by, The application relates to a laser spatial modulation module, an atomic fluorescence encoding module and a collection and processing module. The laser spatial modulation module comprises a coupling light laser, a Rydberg light laser, a laser shaping module and a probe light encoding module. The probe light encoding module comprises a probe light laser, a digital microscopic array and a first plano-convex lens. The atomic fluorescence encoding module comprises an atomic gas chamber and a terahertz source. The laser shaping module is used for shaping the laser spots emitted by the coupling light laser and the Rydberg light laser into light sheets respectively, and combining the two shaped lasers into a beam which is injected into the atomic gas chamber. The first plano-convex lens is used for expanding the beam of the probe light emitted by the probe light laser, so that the spot area of the probe light is larger than the modulation area of the digital microscopic array. The digital microscopic array is used for spatially modulating the probe light and vertically injecting the probe light into the atomic gas chamber, so that the probe light obtains spatial structure information before entering the atomic gas chamber. The atomic gas chamber is used for providing a terahertz wave encoding area. The terahertz source is used for emitting a terahertz wave which covers the whole atomic gas chamber, converting the spatial information of the encoded probe light into spatial encoding of the terahertz wave, and converting the terahertz wave into a visible light signal during the encoding. The collection and processing module is used for receiving the visible light signal and converting the received visible light signal into an electric signal. The collection and processing module is also used for obtaining the intensity information of the visible light according to the voltage of the electric signal, and obtaining the correlation measurement result of the imaging target. The laser shaping module comprises a first shaping lens group, a second shaping lens group and a dichroic mirror.

2. The atomic fluorescence encoded terahertz single-pixel imaging device of claim 1, wherein, The optical path of the first shaping lens group is perpendicular to the optical path of the second shaping lens group. The first shaping lens group and the second shaping lens group are both used for shaping the laser spot into a light sheet. The collection and processing module comprises a visible light lens and a photodetector.

3. The atomic fluorescence encoded terahertz single-pixel imaging device of claim 1, wherein, The visible light lens is used for focusing the visible light to the signal receiving port of the photodetector, so that the photodetector can receive all the visible light signals. The wavelength of the probe light is 852 nm.

4. The atomic fluorescence encoded terahertz single-pixel imaging device of claim 1, wherein, The wavelength of the coupling light emitted by the coupling light laser is 1470 nm.

5. The atomic fluorescence encoded terahertz single-pixel imaging device of claim 4, wherein, The wavelength of the Rydberg light emitted by the Rydberg light laser is 843 nm.

6. The atomic fluorescence encoded terahertz single-pixel imaging device of claim 5, wherein, The first shaping lens group and the second shaping lens group both comprise a second plano-convex lens and a cylindrical lens.

7. The atomic fluorescence encoded terahertz single-pixel imaging device of claim 2, wherein, ​

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