A terahertz holographic fluorescence imaging system and method

Abstract

The present invention provides a terahertz holographic fluorescence imaging system, comprising a terahertz source, a terahertz wave beam splitting module, a terahertz wave beam combining module, an atomic gas chamber in which atoms are stimulated to transition to Rydberg states, and an image acquisition module arranged in sequence, wherein the image acquisition module is communicatively connected with a data processing module; a detection light path and a reference light path are provided between the terahertz wave beam splitting module and the terahertz wave beam combining module, a sample stage and a first terahertz wave attenuator on the detection light path, a removable light blocking member and a second terahertz wave attenuator on the reference light path, and a terahertz wave delay module located on one of the detection light path and the reference light path. The present invention also provides an imaging method. The imaging system of the present invention combines the advantages of high-speed imaging and high sensitivity of terahertz imaging technology based on atomic wireless sensing, and can extract the intensity and phase information of the object to be imaged at high speed, thereby realizing high-speed and high-sensitivity terahertz holographic imaging.

Description

Technical Field

[0001] The present invention relates to the field of terahertz imaging, and more specifically to a terahertz holographic fluorescence imaging system and method. Background Art

[0002] Terahertz (THz) waves are located between microwaves and infrared light in the electromagnetic spectrum, and are in the transition stage from macroscopic electronics to microscopic photonics, covering the characteristic energy of semiconductors and plasmas, and the rotational and vibrational energy of organic and biological molecules. Terahertz waves have unique properties such as high penetration, low energy, and fingerprint spectroscopy. These properties make terahertz imaging technology have potential application value in multidisciplinary frontier fields such as national security, intelligent communications, and biomedicine.

[0003] Although terahertz has important application value, terahertz imaging technology has always been a difficult problem in the terahertz field. Current terahertz imaging technology can be divided into two categories according to the type of detector: the first method is to use terahertz detectors, usually including thermal detectors, photoelectric detectors, quantum detectors, field effect transistor detectors, graphene detectors, etc., to directly detect terahertz radiation; the second method is based on atomic wireless sensing.

[0004] Among them, the first method requires dedicated terahertz detection equipment. Thermal detectors such as Michelson interferometers and thermopiles have long response times. Photoelectric detectors such as photoconductive antennas and microwave photon detectors and quantum detectors such as superconducting detectors and quantum cascade detectors require extremely low operating temperatures and such equipment has complex processes and high manufacturing costs. Field effect transistor detectors and graphene detectors face problems such as high noise levels, poor temperature and environmental stability, and high manufacturing costs.

[0005] The second method is based on atomic wireless sensing technology, which can convert terahertz light into visible light imaging, so visible light camera can be used for imaging. This method has many advantages: 1. Far-field imaging; 2. Fast imaging rate; 3. High sensitivity, which can image weak terahertz fields.

[0006] However, there is currently no reported method for obtaining the phase information of the object to be imaged in the terahertz imaging method based on atomic wireless sensing technology, and therefore it is impossible to achieve holographic imaging of the object to be imaged.

[0007] In order to realize terahertz holographic imaging based on atomic wireless sensing technology, it is necessary to propose a terahertz holographic fluorescence imaging system and method. Summary of the invention

[0008] The object of the present invention is to provide a terahertz holographic fluorescence imaging system and method to achieve high-speed and high-sensitivity terahertz holographic imaging.

[0009] Based on the above purpose, the present invention provides a terahertz holographic fluorescence imaging system, comprising a terahertz source, a terahertz wave beam splitting module, a terahertz wave beam combining module, an atomic gas chamber in which atoms are stimulated to transition to Rydberg states, and an image acquisition module, which are arranged in sequence along the direction of an optical path, and the image acquisition module is communicatively connected to a data processing module; a detection light path and a reference light path separated from each other are provided between the terahertz wave beam splitting module and the terahertz wave beam combining module, a sample stage for fixing an object to be imaged and a first terahertz wave attenuator on the detection light path, a removable light blocking member and a second terahertz wave attenuator on the reference light path, and a terahertz wave delay module located on one of the detection light path and the reference light path.

[0010] A terahertz wave shaping module is provided between the terahertz source and the terahertz wave splitting module. The terahertz wave shaping module includes a terahertz collimating lens, a beam expanding device and a first terahertz polarizer. The terahertz source is located at the focus of the terahertz collimating lens. The terahertz wave emitted by the terahertz source is collimated by the terahertz collimating lens and then passes through the beam expanding device. The beam expanding device expands the terahertz wave and then converts it into linearly polarized light through the first terahertz polarizer.

[0011] The first terahertz wave attenuator and the second terahertz wave attenuator each include at least one of a terahertz wave polarizer and a terahertz wave attenuation plate.

[0012] The first terahertz wave attenuation module includes a second terahertz polarizer and a third terahertz polarizer, wherein the polarization direction of the second terahertz polarizer is adjustable, and the polarization direction of the third terahertz polarizer is fixed and consistent with the polarization direction of the first terahertz polarizer; the second terahertz wave attenuation module includes a fourth terahertz polarizer and a fifth terahertz polarizer, wherein the polarization direction of the fourth terahertz polarizer is adjustable, and the polarization direction of the fifth terahertz polarizer is fixed and consistent with the polarization direction of the first terahertz polarizer.

[0013] A laser module is also provided upstream of the atomic gas chamber, and the laser module includes a first laser, a second laser and a third laser, wherein the first laser is used to generate a first laser of a first wavelength, and the first laser excites atoms from a ground state to a first transition state; the second laser is used to generate a second laser of a second wavelength, and the second laser excites atoms to a second transition state; the third laser is used to generate a third laser of a third wavelength; the third laser excites atoms to a Rydberg state lower energy level; the atomic gas chamber is configured to excite atoms to a Rydberg state upper energy level through the terahertz wave when receiving the terahertz wave, and then de-excite to the first transition state and radiate visible fluorescence.

[0014] A laser shaping module is provided between the atomic gas chamber and the laser module, and the laser shaping module comprises a first shaping device, a first beam splitter and a second shaping device, the first laser, the second laser, the first shaping device and the first beam splitter are all located on the first side of the atomic gas chamber, and the third laser and the second shaping device are all located on the second side of the atomic gas chamber; the first laser, the first beam splitter and the first shaping device are arranged in sequence along the first laser optical path, the second laser, the first beam splitter and the first shaping device are arranged in sequence along the second laser optical path, and the third laser and the second shaping device are arranged in sequence along the third laser optical path.

[0015] The first shaping device and the second shaping device both include a prism pair and a cylindrical lens group arranged in sequence to shape the laser into a thin sheet with uniform light intensity distribution, and irradiate the laser to the atomic gas chamber along a direction perpendicular to the transmission direction of the terahertz wave.

[0016] The terahertz holographic fluorescence imaging system satisfies at least one of the following:

[0017] a1) a terahertz focusing module is provided between the terahertz wave combining module and the atomic gas chamber, wherein the terahertz focusing module comprises an imaging lens group, wherein the imaging lens group comprises a terahertz convex lens and a terahertz concave lens;

[0018] a2) a terahertz wave transmission module is provided on one of the detection light path and the reference light path;

[0019] a3) the removable light blocking member is an electronic aperture, and the electronic aperture is a chopper;

[0020] a4) The terahertz wave delay module includes one of an acousto-optic modulator, a reflector, a plane lens, and a micro-electromechanical system.

[0021] On the other hand, the present invention provides a terahertz holographic fluorescence imaging method, which is implemented by using the terahertz holographic fluorescence imaging system as described above, comprising the following steps:

[0022] S100, starting the terahertz source and causing atoms in the atomic gas chamber to be stimulated to transition to a Rydberg state;

[0023] S200, adjusting the first terahertz wave attenuation module so that the intensity of the detection light is attenuated to 0; moving the removable light blocking member out of the optical path so that only the reference light is incident on the atomic gas chamber through the terahertz wave beam combining module; adjusting the second terahertz wave attenuation module to attenuate the intensity of the reference light until the intensity of the reference light is far away from the terahertz wave incident intensity corresponding to the saturation absorption of the atomic gas chamber; using the image acquisition module and the data processing module to collect the fluorescence generated by the atomic gas chamber and process it to obtain the relative intensity of the reference light as the calibration intensity;

[0024] S300, moving the removable light blocking member into the optical path so that the atomic gas chamber shields the reference light and only allows the detection light to enter; adjusting the first terahertz wave attenuation module until the relative intensity of the detection light acquired and processed by the image acquisition module and the data processing module is close to the calibrated intensity in S200;

[0025] S400, moving the removable light blocking member out of the optical path so that the detection light and the reference light pass through the terahertz wave beam combining module and simultaneously enter the atomic gas chamber; adjusting the terahertz wave delay module so that the detection light and the reference light are coherently destructed to the greatest extent;

[0026] S500, moving the removable light blocking member into the optical path, fixing the object to be imaged on the sample stage, so that the detection light carries imaging information after reflecting or transmitting the object to be imaged; using the image acquisition module to acquire a fluorescent image containing only the intensity information of the object to be imaged;

[0027] S600, moving the removable light blocking member out of the light path, so that the detection light carrying imaging information and the reference light are incident on the atomic gas chamber and interfere with each other; using the image acquisition module to acquire a fluorescent image containing phase information of the object to be imaged;

[0028] S700 , using the data processing module to compare and calculate the fluorescence images of S500 and S600 , so as to obtain the intensity and phase information of the terahertz imaging of the object to be imaged.

[0029] The terahertz holographic fluorescence imaging system of the present invention combines the advantages of high-speed imaging and high sensitivity of terahertz imaging technology based on atomic wireless sensing, and can extract the intensity and phase information of the object to be imaged at high speed, thereby realizing high-speed and high-sensitivity terahertz holographic imaging. In addition, the terahertz holographic fluorescence imaging system of the present invention not only extracts the intensity information of the object to be imaged, but also extracts the phase information of the object to be imaged on the basis of atomic wireless sensing technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a structural block diagram of a terahertz holographic fluorescence imaging system according to an embodiment of the present invention.

[0031] Figure 2 Yes Figure 1 The optical path diagram of the terahertz holographic fluorescence imaging system is shown.

[0032] Figure 3 is a flow chart of a terahertz holographic fluorescence imaging method according to another embodiment of the present invention. DETAILED DESCRIPTION

[0033] Embodiments of the present invention are given below in conjunction with the accompanying drawings and described in detail.

[0034] like Figure 1 and Figure 2 The figure shows a terahertz holographic fluorescence imaging system according to an embodiment of the present invention, which includes a terahertz source 10, a terahertz wave shaping module 40, a terahertz wave beam splitting module 50, parallel detection light components and reference light components, a terahertz wave beam combining module 120 located downstream of the detection light component and the reference light component, a terahertz focusing module 130, an atomic gas chamber 140, and an image acquisition module 150, which are arranged in sequence along the direction of the optical path. The image acquisition module 150 is connected to a data processing module 160.

[0035] The terahertz wave beam splitting module 50 is used to split the terahertz wave emitted by the terahertz source 10 into two beams, one beam is used as a detection light, passes through the detection light component to carry the imaging information of the object to be imaged, and finally propagates to the terahertz wave beam combining module 120, and the other beam is used as a reference light, passes through the reference light component to propagate to the terahertz wave beam combining module 120. Accordingly, the terahertz wave beam combining module 120 is used to combine the detection light and the reference light into one beam without changing the wavefront. In this embodiment, the terahertz wave beam splitting module 50 and the terahertz wave beam combining module 120 both include a terahertz beam splitter.

[0036] The detection light assembly is installed with an object to be imaged, including a terahertz wave delay module 80, a terahertz wave first attenuation module 90, and a sample stage 100 arranged in sequence along the direction of the light path, and the sample stage 100 is used to install the object to be imaged. The reference light assembly includes a terahertz wave transmission module 60, an electronic aperture 70, and a terahertz wave second attenuation module 110 arranged in sequence along the direction of the light path.

[0037] In some embodiments, the terahertz source 10 is used to emit terahertz waves, and the operating frequency range may be 0.1THz-2THz. The operating frequency of the terahertz source is selected according to actual imaging system parameters. For example, the operating frequency of the terahertz source 10 may be 550GHz.

[0038] A laser module 20 is further provided upstream of the atomic gas cell 140 . The laser module 20 is configured to emit laser light of at least one specific frequency, and the atoms in the atomic gas cell 140 are excited to the Rydberg state energy level by the laser light.

[0039] In some embodiments, the laser module 20 can generate lasers of three wavelengths, including a first laser 21, a second laser 22 and a third laser 23. The first laser 21 is used to generate a first laser of a first wavelength (e.g., 852 nm), the second laser 22 is used to generate a second laser of a second wavelength (e.g., 1450 nm), and the third laser 23 is used to generate a third laser of a third wavelength (e.g., 843 nm).

[0040] In some embodiments, in the laser module 20, the wavelength of the first laser can be 852nm, which can excite the alkali metal atoms from the ground state 6S1 / 2 to the first transition state 6P3 / 2, the wavelength of the second laser can be 1450nm, which can excite the alkali metal atoms to the second transition state 7S1 / 2, and the wavelength of the third laser can be 843nm, which can excite the alkali metal atoms to the Rydberg lower energy level 14P 3 / 2 .

[0041] The atomic gas chamber 140 contains atoms that are stimulated to transition to the Rydberg state. The atoms are preferably alkali metal atomic vapor. In this embodiment, the atomic gas chamber 140 contains cesium atoms that are stimulated to transition to the Rydberg state.

[0042] The atomic gas chamber 140 is configured to, when receiving a terahertz wave, excite the atoms to the upper energy level of the Rydberg state through the terahertz wave, and then de-excite and radiate visible fluorescence for imaging. Specifically, when a terahertz wave (such as a terahertz wave with a frequency of 0.55 THz) carrying information of the object to be imaged is irradiated to the atomic gas chamber 140 along a direction perpendicular to the transmission direction of the three lasers, the atoms are excited to the upper energy level 13D of the Rydberg state. 5 / 2 , and then de-excited to the first excited state 6P 3 / 2 And radiate visible fluorescence signal with a wavelength of 530nm.

[0043] A laser shaping module 30 is provided between the atomic gas chamber 140 and the laser module 20 . The laser shaping module 30 is used to shape the laser of the laser module 20 and transmit the lasers of all the laser modules 20 to the atomic gas chamber 140 simultaneously.

[0044] In this embodiment, the laser shaping module 30 includes a first shaping device 32, a first beam splitter 31 and a second shaping device 33. The first laser 21, the second laser 22, the first shaping device 32 and the first beam splitter 31 are all located on the first side of the atomic gas chamber 140, and the third laser 23 and the second shaping device 33 are both located on the second side of the atomic gas chamber 140.

[0045] Therefore, the first laser 21, the first beam splitter 31 and the first shaping device 32 are arranged in sequence along the first laser optical path, and the second laser 22, the first beam splitter 31 and the first shaping device 32 are arranged in sequence along the second laser optical path. The third laser 23 and the second shaping device 33 are arranged in sequence along the third laser optical path. That is to say, after the lasers of the first laser 21 and the second laser 22 are combined through the first beam splitter 31 (the laser of the first laser 21 passes through the first beam splitter 31, and the laser of the second laser 22 is combined after being reflected by the first beam splitter 31 and reaches the first shaping device), they are shaped through the first shaping device 32 and irradiated to the atomic gas chamber 140 along a direction perpendicular to the transmission direction of the terahertz wave. The laser of the third laser 23 is irradiated to the second shaping device 33, shaped through the second shaping device 33 and irradiated to the atomic gas chamber 140 along a direction perpendicular to the transmission direction of the terahertz wave. Therefore, the light fields of the three shaped laser beams and the light field of the terahertz wave overlap spatially on the atomic gas chamber 140. The side incidence of the laser excites the cesium atoms to the Rydberg upper energy level, forming a planar area that can be used to detect terahertz, and then the terahertz wave vertically incident on this area will produce fluorescence.

[0046] In this embodiment, the first shaping device 32 and the second shaping device 33 both include a prism pair and a cylindrical lens group arranged in sequence to shape the laser into a thin sheet with uniform light intensity distribution, and irradiate the laser to the atomic gas chamber 140 along a direction perpendicular to the transmission direction of the terahertz wave.

[0047] The terahertz shaping module 40 is used to collimate and expand the terahertz wave emitted by the terahertz source 10, and convert it into linearly polarized light. In some embodiments, the terahertz shaping module 40 may include a terahertz collimating lens 41, a beam expander 42, and a first terahertz polarizer 43. The terahertz source 10 is located at the focus of the terahertz collimating lens 41, and the terahertz wave emitted by the terahertz source 10 passes through the beam expander 42 after being collimated by the terahertz collimating lens. The beam expander 42 expands the terahertz wave and converts it into linearly polarized light through the first terahertz polarizer 43.

[0048] In some embodiments, the first terahertz wave attenuation module 90 may include a second terahertz polarizer 91 and a third terahertz polarizer 92, wherein the polarization direction of the second terahertz polarizer 91 is adjustable, and the polarization direction of the third terahertz polarizer 92 is fixed and consistent with the terahertz polarizer 43. Thus, by adjusting the polarization angle of the second terahertz polarizer 91 relative to the first terahertz polarizer 43, the intensity of the detection light can be adjusted through the first terahertz wave attenuation module 90, and the polarization direction can be maintained.

[0049] The second terahertz wave attenuation module 110 is used to adjust the intensity of the reference light. In some embodiments, the second terahertz wave attenuation module 110 may include a fourth terahertz polarizer 111 and a fifth terahertz polarizer 112, wherein the polarization direction of the fourth terahertz polarizer 111 is adjustable, and the polarization direction of the fifth terahertz polarizer 112 is fixed and consistent with the first terahertz polarizer 43. Thus, by adjusting the polarization angle between the fourth terahertz polarizer 111 and the first terahertz polarizer 43, the intensity of the reference light can be adjusted by the second terahertz wave attenuation module 110, and the polarization direction can be maintained.

[0050] In other embodiments, the first terahertz wave attenuator 90 and the second terahertz wave attenuator 110, including but not limited to using a terahertz wave polarizer and a terahertz wave attenuation plate, are respectively used to adjust the intensity of the detection light and the reference light, so that the intensity of the detection light received at the terahertz wave beam combining module 120 is close to the intensity of the reference light, and the total intensity of the terahertz wave output by the terahertz wave beam combining module 120 is lower than the terahertz wave incident intensity corresponding to the saturated absorption of the atomic gas chamber.

[0051] In other embodiments, the first terahertz wave attenuator 90 and the second terahertz wave attenuator 110 can be replaced by a total terahertz wave attenuator located upstream of the terahertz wave beam splitting module 50, or the terahertz wave attenuator can be omitted and the intensity of the detection light and the reference light can be changed by simply adjusting the intensity of the terahertz source 10.

[0052] The terahertz wave transmission module 60 is used to change the propagation path of the terahertz wave, which includes but is not limited to a metal-coated reflector. In other embodiments, the terahertz wave transmission module 60 is arranged on one of the detection light path and the reference light path to change the propagation path of the detection light or the reference light without changing the wavefront.

[0053] The electronic aperture 70 is used to open and close the propagation channel of the reference light at high speed. In some embodiments, the electronic aperture 70 can be implemented by a chopper, which can complete high-speed on-off control of the optical path, and its switching frequency can reach 100kHz. In other embodiments, the electronic aperture 70 can be replaced by other types of removable light blocking members.

[0054] The terahertz wave delay module 80 is used to adjust the optical path of the detection light without changing the wavefront of the detection light. In some embodiments, the terahertz wave delay module 80 may include two high-resistance silicon plane lenses 81 and an angle adjustment device 82, the thickness of the high-resistance silicon plane lenses may be about 1 mm, and the angle adjustment device is used to change and fix the angle between the plane lenses. In other embodiments, the terahertz wave delay module 80 includes but is not limited to one of an acousto-optic modulator, a reflector, a plane lens, a micro-electromechanical system, etc., and the terahertz wave delay module 80 may be set on any one of the detection light path and the reference light path.

[0055] The sample stage 100 is used to mount the object to be imaged. The sample stage 100 includes a sample limiting device and a three-dimensional motion mechanism. The sample limiting device is used to fix the object to be imaged, and the two-dimensional motion mechanism is used to finely adjust the spatial position of the object to be imaged.

[0056] The terahertz focusing module 130 is used to focus the terahertz wave onto the atomic gas chamber 140. In some embodiments, the terahertz focusing module 130 may include an imaging lens group, which includes a terahertz convex lens 131 and a terahertz concave lens 132, and is used to converge the terahertz light. The size of the image of the terahertz wave in the atomic gas chamber 140 can be adjusted by changing the layout of the imaging lens group.

[0057] The image acquisition module 150 is used to acquire and store the fluorescence image from the atomic gas chamber. In some embodiments, the image acquisition module 150 may include a focusing lens 152, a narrow-band filter 151, and a multi-pixel high-speed visible light camera 153 arranged in sequence, the focusing lens 152 is used to focus the visible light signal carrying the sample information to be imaged in the atomic gas chamber 140 to the multi-pixel high-speed visible light camera 153, the narrow-band filter 151 is used to remove the stray light in the visible light signal to improve the imaging quality; the multi-pixel high-speed visible light camera 153 is used to record the fluorescence image of the atomic gas chamber in real time.

[0058] The data processing module 160 performs data processing on the fluorescent image collected by the image acquisition module 150 to complete the pre-imaging calibration of the terahertz holographic fluorescence imaging system and extract the intensity and phase information. The pre-imaging calibration of the terahertz holographic fluorescence imaging system includes the calibration of the first terahertz wave attenuation module 90, the second terahertz wave attenuation module 110, and the terahertz wave delay module 80. The extracted intensity and phase information is used to calculate the intensity and phase information of the terahertz wave reflected or transmitted by the object to be imaged. In some embodiments, the data processing module 160 can be a device equipped with a high-performance programmable logic device such as an FPGA, and its communication with the image acquisition module 150 can be achieved through a network port. In this embodiment, the data processing module 160 is connected to the image acquisition module 150 through a Gigabit Ethernet port.

[0059] Although the embodiments of the present application have been shown and described above, the scope of protection of the present invention is not limited thereto, and any changes or substitutions that are not conceivable through creative work should be included in the scope of protection of the present invention; unless explicitly stated, any elements, actions or instructions used in this document should not be interpreted as critical or necessary.

[0060] like Figure 3 As shown, another embodiment of the present invention provides a terahertz holographic fluorescence imaging method, which is implemented using the ultra-high resolution terahertz imaging system of the above embodiment and includes the following steps:

[0061] S100: starting the terahertz source 10 and starting the laser module 20 to stimulate the cesium atoms in the atomic gas chamber 140 to transition to the Rydberg state;

[0062] S200: Adjust the first terahertz wave attenuation module 90 so that the intensity of the detection light is attenuated to 0; open the electronic aperture 70 (i.e., move the removable light blocking member out of the light path) so that only the reference light is incident on the atomic gas chamber 140 through the terahertz wave beam combining module 120; adjust the second terahertz wave attenuation module 110 to attenuate the intensity of the reference light until the intensity of the reference light is far away from the terahertz wave incident intensity corresponding to the saturation absorption of the atomic gas chamber 140; use the image acquisition module 150 and the data processing module 160 to collect the fluorescence generated by the atomic gas chamber 140 and process it to obtain the relative intensity of the reference light as the calibration intensity.

[0063] When saturated absorption occurs, the intensity of the terahertz wave increases while the fluorescence intensity of the atomic gas chamber cannot be increased. In order to correlate the terahertz intensity to the fluorescence intensity, it is necessary to image at a minimum terahertz intensity far away from the saturated absorption. In this embodiment, the intensity of the reference light is far away from the terahertz wave incident intensity corresponding to the saturated absorption of the atomic gas chamber 140, which can be defined as the terahertz light intensity corresponding to the saturated absorption being more than 10 times the reference light intensity.

[0064] In the process of adjusting the second terahertz wave attenuation module 110, the reference light intensity is adjusted to increase by 10 times, and the fluorescence is measured to determine whether the intensity of the reference light is far away from the terahertz wave incident intensity corresponding to the saturation absorption of the atomic gas cell. If the fluorescence is enhanced by a corresponding multiple, it means that the intensity of the reference light is far away from the terahertz wave incident intensity corresponding to the saturation absorption of the atomic gas cell.

[0065] S300: Close the electronic aperture 70 (i.e., move the removable light blocking member into the light path) so that the atomic gas chamber 140 shields the reference light and only allows the detection light to enter; adjust the first terahertz wave attenuation module 90 until the relative intensity of the detection light acquired and processed by the image acquisition module 150 and the data processing module 160 is close to the calibrated intensity in S200.

[0066] S400: Open the electronic aperture 70 (i.e., move the removable light blocking member out of the light path), so that the detection light and the reference light are incident on the atomic gas chamber 140 at the same time through the terahertz wave beam combining module 120; at this time, adjust the terahertz wave delay module 80 so that the detection light and the reference light are coherently destructed to the maximum extent, wherein, when the fluorescence intensity of the atomic gas chamber 140 calculated by the data processing module 160 reaches the minimum value, it indicates that the maximum detection light and the reference light are coherently destructed to the maximum extent and the terahertz wave delay adjustment is completed; at this time, the calibration of the terahertz holographic fluorescence imaging system of the present invention is completed.

[0067] S500: Close the electronic aperture 70 (i.e., move the removable light blocking member into the light path), fix the object to be imaged on the sample stage 100, so that the detection light carries imaging information after reflecting or transmitting the object to be imaged, and then the detection light passes through the terahertz wave beam combining module 120 and enters the atomic gas chamber to generate fluorescence; use the image acquisition module 150 to acquire a fluorescence image that only contains the intensity information of the object to be imaged.

[0068] S600: Open the electronic aperture 70 (i.e., move the removable light blocking member out of the light path), so that the detection light carrying the imaging information and the reference light pass through the terahertz wave beam combining module 120 and simultaneously enter the atomic gas chamber 140 and interfere, so as to generate fluorescence in the atomic gas chamber 140; use the image acquisition module 150 to acquire a fluorescence image containing the phase information of the object to be imaged.

[0069] S700: using the data processing module 160 to compare and calculate the fluorescence images of S500 and S600 to obtain the intensity and phase information of the terahertz imaging of the object to be imaged.

[0070] The above is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. The above embodiments of the present invention can also be modified in various ways. All simple, equivalent changes and modifications made according to the claims and the description of the present invention fall within the scope of protection of the claims of the present invention. The contents not described in detail in the present invention are all conventional technical contents.

Claims

1. A terahertz holographic fluorescence imaging method, characterized in that: It is implemented by a terahertz holographic fluorescence imaging system, which includes a terahertz source, a terahertz wave beam splitting module, a terahertz wave beam combining module, an atomic gas chamber in which atoms are stimulated to transition to a Rydberg state, and an image acquisition module, which is arranged in sequence along the direction of the optical path, and the image acquisition module is communicatively connected with the data processing module; A detection light path and a reference light path separated from each other are provided between the terahertz wave beam splitting module and the terahertz wave beam combining module, a sample stage for fixing an object to be imaged and a first terahertz wave attenuator are provided on the detection light path, a removable light blocking member and a second terahertz wave attenuator are provided on the reference light path, and a terahertz wave delay module is provided on one of the detection light path and the reference light path; The method comprises the following steps: S100, start the terahertz source and make the atoms in the atomic gas chamber transition to the Rydberg state; S200, adjusting the first terahertz wave attenuation module to make the detection light intensity attenuate to 0; moving the removable light blocking member out of the light path so that only the reference light is incident on the atomic gas chamber through the terahertz wave beam combining module; adjusting the second terahertz wave attenuation module to attenuate the intensity of the reference light until the intensity of the reference light is far away from the terahertz wave incident intensity corresponding to the saturation absorption of the atomic gas chamber; using the image acquisition module and the data processing module to collect the fluorescence generated by the atomic gas chamber and process it to obtain the relative intensity of the reference light as the calibration intensity; In the process of adjusting the second terahertz wave attenuation module, the reference light intensity is adjusted to increase by 10 times, and whether the fluorescence is enhanced by a corresponding multiple is measured to determine whether the intensity of the reference light is far away from the terahertz wave incident intensity corresponding to the saturated absorption of the atomic gas chamber; if the fluorescence is enhanced by a corresponding multiple, it means that the intensity of the reference light is far away from the terahertz wave incident intensity corresponding to the saturated absorption of the atomic gas chamber; S300, moving the removable light blocking member into the optical path so that the atomic gas chamber shields the reference light and only allows the detection light to enter; adjusting the first terahertz wave attenuation module until the relative intensity of the detection light acquired and processed by the image acquisition module and the data processing module is close to the calibrated intensity in S200; S400, moving the removable light blocking member out of the optical path so that the detection light and the reference light pass through the terahertz wave beam combining module and enter the atomic gas chamber at the same time; adjusting the terahertz wave delay module so that the detection light and the reference light are coherently destructed to the greatest extent; S500, moving the removable light blocking member into the optical path, fixing the object to be imaged on the sample stage, so that the detection light carries imaging information after reflecting or transmitting the object to be imaged; using the image acquisition module to acquire a fluorescent image containing only the intensity information of the object to be imaged; S600, moving the removable light blocking member out of the light path, so that the detection light carrying imaging information and the reference light are incident on the atomic gas chamber and interfere with each other; using the image acquisition module to acquire a fluorescent image containing phase information of the object to be imaged; S700 , using the data processing module to compare and calculate the fluorescence images of S500 and S600 , so as to obtain the intensity and phase information of the terahertz imaging of the object to be imaged.

2. The terahertz holographic fluorescence imaging method according to claim 1, characterized in that: A terahertz wave shaping module is provided between the terahertz source and the terahertz wave splitting module. The terahertz wave shaping module includes a terahertz collimating lens, a beam expanding device and a first terahertz polarizer. The terahertz source is located at the focus of the terahertz collimating lens. The terahertz wave emitted by the terahertz source is collimated by the terahertz collimating lens and then passes through the beam expanding device. The beam expanding device expands the terahertz wave and then converts it into linearly polarized light through the first terahertz polarizer.

3. The terahertz holographic fluorescence imaging method according to claim 2, characterized in that: The first terahertz wave attenuator and the second terahertz wave attenuator each include at least one of a terahertz wave polarizer and a terahertz wave attenuation plate.

4. The terahertz holographic fluorescence imaging method according to claim 3, characterized in that: The first terahertz wave attenuation module comprises a second terahertz polarizer and a third terahertz polarizer, wherein the polarization direction of the second terahertz polarizer is adjustable, and the polarization direction of the third terahertz polarizer is fixed and consistent with the polarization direction of the first terahertz polarizer; The second terahertz wave attenuation module comprises a fourth terahertz polarizer and a fifth terahertz polarizer, wherein the polarization direction of the fourth terahertz polarizer is adjustable, and the polarization direction of the fifth terahertz polarizer is fixed and consistent with the polarization direction of the first terahertz polarizer.

5. The terahertz holographic fluorescence imaging method according to claim 1, characterized in that: A laser module is also provided upstream of the atomic gas chamber, and the laser module includes a first laser, a second laser and a third laser, wherein the first laser is used to generate a first laser of a first wavelength, and the first laser excites atoms from a ground state to a first transition state; the second laser is used to generate a second laser of a second wavelength, and the second laser excites atoms to a second transition state; the third laser is used to generate a third laser of a third wavelength; the third laser excites atoms to a Rydberg state lower energy level; the atomic gas chamber is configured to excite atoms to a Rydberg state upper energy level through the terahertz wave when receiving the terahertz wave, and then de-excite to the first transition state and radiate visible fluorescence.

6. The terahertz holographic fluorescence imaging method according to claim 5, characterized in that: A laser shaping module is provided between the atomic gas chamber and the laser module, and the laser shaping module comprises a first shaping device, a first beam splitter and a second shaping device, the first laser, the second laser, the first shaping device and the first beam splitter are all located on the first side of the atomic gas chamber, and the third laser and the second shaping device are all located on the second side of the atomic gas chamber; the first laser, the first beam splitter and the first shaping device are arranged in sequence along the first laser optical path, the second laser, the first beam splitter and the first shaping device are arranged in sequence along the second laser optical path, and the third laser and the second shaping device are arranged in sequence along the third laser optical path.

7. The terahertz holographic fluorescence imaging method according to claim 6, characterized in that: The first shaping device and the second shaping device both include a prism pair and a cylindrical lens group arranged in sequence to shape the laser into a thin sheet with uniform light intensity distribution, and irradiate the laser to the atomic gas chamber along a direction perpendicular to the transmission direction of the terahertz wave.

8. The terahertz holographic fluorescence imaging method according to claim 1, characterized in that: The terahertz holographic fluorescence imaging system satisfies at least one of the following: a1) a terahertz focusing module is provided between the terahertz wave combining module and the atomic gas chamber, wherein the terahertz focusing module comprises an imaging lens group, wherein the imaging lens group comprises a terahertz convex lens and a terahertz concave lens; a2) a terahertz wave transmission module is provided on one of the detection light path and the reference light path; a3) the removable light blocking member is an electronic aperture, and the electronic aperture is a chopper; a4) The terahertz wave delay module includes one of an acousto-optic modulator, a reflector, a plane lens, and a micro-electromechanical system.

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