Terahertz polarization imaging system

Abstract

The application discloses a terahertz polarization imaging system, which comprises a terahertz emitting device for emitting a linearly polarized beam, a reflection shaping component, a sample supporting device and a terahertz receiving device arranged in sequence along the light path propagation direction of the linearly polarized beam; the terahertz emitting device comprises a terahertz emitting mechanism capable of rotating around the linearly polarized beam emitting direction as an axis, and the terahertz emitting mechanism is used for emitting the linearly polarized beam; the reflection shaping component is used for reflecting and collimating and shaping the linearly polarized beam; the sample supporting device is used for supporting a sample and making the sample located on the light path reflected by the reflection shaping component; and the terahertz receiving device is used for receiving the linearly polarized beam. The terahertz polarization imaging system can acquire the polarization information of the sample in the terahertz wave band, and can be used for realizing high-resolution polarization imaging.

Description

Technical Field

[0001] This invention belongs to the field of terahertz technology, and specifically relates to a terahertz polarization imaging system. Background Technology

[0002] Terahertz (THz) imaging technology is an emerging non-destructive testing method. Due to its unique position in the electromagnetic spectrum, between microwaves and infrared, it possesses advantages such as strong penetration, non-ionization, and sensitivity to certain materials. Terahertz non-destructive testing systems have shown broad application potential in materials science, biomedical imaging, and security inspection. However, existing terahertz non-destructive testing systems mainly focus on acquiring the amplitude intensity information of the tested sample, lacking the measurement and analysis of polarization information.

[0003] Polarization information is a crucial property of electromagnetic waves, providing supplementary information about a sample's structure, composition, and surface characteristics. For example, in biological tissue imaging, polarization information helps distinguish tissues with different molecular orientations; in materials science, it can be used to identify the anisotropic characteristics of materials. Therefore, terahertz imaging systems lacking polarization information perform poorly in detecting high-transmittance samples, limiting their detection capabilities in certain applications.

[0004] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide a terahertz polarization imaging system that can acquire polarization information of a sample in the terahertz band and can be used to achieve high-resolution polarization imaging.

[0006] To achieve the above objectives, a specific embodiment of the present invention provides the following technical solution: a terahertz polarization imaging system, comprising a terahertz emission device for emitting a linearly polarized beam, and a reflection shaping component, a carrier device, and a terahertz receiving device arranged sequentially along the optical path propagation direction of the linearly polarized beam.

[0007] The terahertz emission device includes a terahertz emission mechanism that can rotate about the direction of linearly polarized beam emission, and the terahertz emission mechanism is used to emit a linearly polarized beam.

[0008] The reflection shaping component is used to reflect linearly polarized beams and collimate and shape them.

[0009] The sample carrier is used to carry the sample and position the sample in the optical path reflected by the reflective shaping component.

[0010] The terahertz receiving device is used to receive linearly polarized beams.

[0011] In one or more embodiments of the present invention, the terahertz emission device includes a rotating mechanism and a base, the terahertz emission mechanism being mounted on the base, and the rotating mechanism being connected to the base to drive the base to rotate about the linearly polarized beam emission direction as an axis.

[0012] In one or more embodiments of the present invention, the terahertz emission mechanism includes a terahertz source capable of emitting linearly polarized beams; or,

[0013] The terahertz emission mechanism includes a terahertz source and a linear polarizer mounted on the terahertz source. The beam emitted from the terahertz source is converted into a linearly polarized beam after passing through the linear polarizer.

[0014] In one or more embodiments of the present invention, the reflection shaping component includes an off-axis collimating mirror and an even-order aspherical shaping mirror arranged sequentially along the optical path propagation direction of the linearly polarized beam; or,

[0015] The reflection shaping component includes an axial collimating mirror, an off-axis microarray mirror group, an off-axis integrating mirror, and a plane mirror group arranged sequentially along the optical path propagation direction of the linearly polarized beam.

[0016] In one or more embodiments of the present invention, the loading device includes a four-dimensional displacement stage and a loading stage disposed on the four-dimensional displacement stage, the loading stage being used to carry a sample.

[0017] In one or more embodiments of the present invention, the four-dimensional displacement stage includes an x-axis linear displacement stage, a y-axis linear displacement stage, a z-axis linear displacement stage, and a y-axis rotary displacement stage.

[0018] In one or more embodiments of the present invention, the terahertz receiving device includes an off-axis three-mirror optical component and a terahertz surface array detector arranged sequentially along the optical path propagation direction of the linearly polarized beam. The off-axis three-mirror optical component is used to converge the linearly polarized beam to the terahertz surface array detector.

[0019] In one or more embodiments of the present invention, the off-axis three-mirror optical assembly includes a primary mirror, a secondary mirror, and a third mirror arranged sequentially along the optical path propagation direction.

[0020] In one or more embodiments of the present invention, the terahertz surface array detector is a terahertz surface array detector with linear polarization detection function; or, a linear polarizer is installed at the receiving end of the terahertz surface array detector.

[0021] In one or more embodiments of the present invention, the terahertz polarization imaging system further includes a host computer, which is electrically connected to the terahertz receiving device and is used to receive information transmitted by the terahertz receiving device.

[0022] Compared with the prior art, the terahertz polarization imaging system of the present invention emits a linearly polarized beam through a terahertz emission device. The linearly polarized beam is reflected and collimated by a reflection shaping component, passes through the sample on the carrier device, and is then received by a terahertz receiving device, thereby obtaining imaging information of the polarized terahertz wave. In addition, the terahertz source can rotate about the emission direction of the linearly polarized beam, that is, rotate the terahertz at 0 degrees, 45 degrees, and 90 degrees. The terahertz receiving device collects the imaging effects under different polarizations, and can use Stokes parameters to calculate the sample polarization imaging information and transmission amplitude intensity imaging information under the polarization state. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a three-dimensional schematic diagram of a terahertz polarization imaging system according to an embodiment of the present invention;

[0025] Figure 2 This is a top view of a terahertz polarization imaging system (including optical path) according to an embodiment of the present invention;

[0026] Figure 3 This is a three-dimensional schematic diagram of the optical path of a terahertz polarization imaging system according to an embodiment of the present invention;

[0027] Figure 4 This is a top view of the optical path of a terahertz polarization imaging system according to an embodiment of the present invention;

[0028] Figure 5 This is a top view of the optical path of a reflection shaping component in one embodiment of the present invention;

[0029] Figure 6 This is a top view of the optical path of the reflection shaping component in another embodiment of the present invention;

[0030] Figure 7 This is a top view of the optical path of an off-axis three-mirror optical component in one embodiment of the present invention;

[0031] Figure 8 This is a distribution diagram of the amplitude of the emitted light spot after passing through the reflection shaping component in one embodiment of the present invention;

[0032] Figure 9 This is a schematic diagram of a linearly distributed terahertz source in one embodiment of the present invention;

[0033] Figure 10 This is a schematic diagram of a linearly distributed terahertz source in one embodiment of the present invention;

[0034] Figure 11 This is a schematic diagram of an elliptical distributed terahertz source in one embodiment of the present invention;

[0035] Figure 12 This is a schematic diagram of a circularly distributed terahertz source in one embodiment of the present invention;

[0036] Figure 13 This is an image of the 0-degree position obtained by a terahertz surface array detector in an example of the present invention;

[0037] Figure 14 This is an image of a terahertz surface array detector at a 90-degree position obtained in an example of the present invention;

[0038] Figure 15 This is a diagram showing the calculated amplitude distribution in the Ey direction obtained from a terahertz surface array detector in an example of the present invention.

[0039] Figure 16 This is a diagram showing the calculated amplitude distribution in the Ex direction obtained from a terahertz surface array detector in an example of the present invention.

[0040] Figure 17 This is an example of an axial ratio diagram obtained from a terahertz surface array detector in this invention.

[0041] Figure 18 This is a test image of the 360-degree amplitude distribution obtained by a terahertz surface array detector in an example of the present invention.

[0042] Explanation of key figure labels:

[0043] 1. Terahertz emission device; 11. Terahertz emission mechanism; 12. Rotation mechanism; 13. Base; 2. Reflection shaping assembly; 21. Off-axis collimating mirror; 22. Even-order aspherical shaping mirror; 3. Object carrier; 31. Four-dimensional displacement stage; 311. X-axis linear displacement stage; 312. Y-axis linear displacement stage; 313. Z-axis linear displacement stage; 314. Y-axis rotary displacement stage; 32. Object stage; 4. Terahertz receiving device; 41. Off-axis three-mirror optical assembly; 411. Primary mirror; 412. Secondary mirror; 413. Third mirror; 42. Terahertz surface array detector; 43. Mounting base. Specific Implementation

[0044] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0045] like Figures 1-4 As shown, a terahertz polarization imaging system according to one embodiment of the present invention includes a terahertz emission device 1 for emitting a linearly polarized beam, and a reflection shaping component 2, a sample carrier 3, and a terahertz receiving device 4 arranged sequentially along the optical path propagation direction of the linearly polarized beam. The terahertz emission device 1 includes a terahertz emission mechanism 11 that can rotate about the emission direction of the linearly polarized beam, and the terahertz emission mechanism 11 is used to emit the linearly polarized beam. The reflection shaping component 2 is used to reflect the linearly polarized beam and collimate and shape it. The sample carrier 3 is used to carry the sample and position the sample on the optical path reflected by the reflection shaping component 2. The terahertz receiving device 4 is used to receive the linearly polarized beam.

[0046] It should be noted that polarization information is one of the important properties of electromagnetic waves, providing supplementary information about sample structure, composition, and surface characteristics. For example, in biological tissue imaging, polarization information can help distinguish tissues with different molecular orientations; in materials science, polarization information can be used to identify the anisotropic characteristics of materials. THz waves (terahertz waves) refer to electromagnetic waves with frequencies ranging from 0.1 THz to 10 THz, and wavelengths ranging from approximately 0.03 to 3 mm, falling between microwaves and infrared.

[0047] It is understandable that the linearly polarized beam (also called a linearly polarized terahertz wave) emitted by the terahertz emission device 1, after being reflected, collimated, and shaped by the reflection shaping component 2, will illuminate and pass through the sample (also called the test sample) located on the object carrier device 3, and then be received by the terahertz receiving device 4. That is, the image information received by the terahertz receiving device 4 is the amplitude intensity image information containing the polarization information of the sample. Since the terahertz emission device 1 emits terahertz waves, the aforementioned sample polarization information is the polarization information of the sample in the terahertz band.

[0048] Additionally, due to Figures 1-4 No samples were set up, so Figure 1 and 2 The position of the loading device 3 (including the stage 32) is slightly off, i.e. Figure 1 and 2The position of the stage 32 in the middle loading device 3 is slightly off. In actual testing, it is necessary to verify the position of the stage 32 in the y-axis direction so that the sample placed on the stage 32 is located in the optical path.

[0049] The amplitude-intensity image information containing sample polarization information mentioned above can directly provide information such as intensity distribution. Furthermore, it can be processed through subsequent calculations to obtain polarization image information, enabling analysis of the polarization characteristics of the sample and achieving high-resolution polarization imaging. Polarization imaging not only improves image contrast and resolution but also provides more physical and chemical information about the sample, thus enabling more accurate non-destructive testing and evaluation.

[0050] In this embodiment, the terahertz emission device 1 includes a terahertz emission mechanism 11 that can rotate about the direction of linear polarization beam emission. That is, the terahertz rotating emission mechanism can collect imaging effects under different polarizations at 0 degrees, 45 degrees and 90 degrees, which is convenient for subsequent calculation and processing using Stokes parameters to obtain polarization image information.

[0051] like Figure 1 and 2 As shown, specifically, the terahertz emission device 1 further includes a rotating mechanism 12 and a base 13. The terahertz emission mechanism 11 is mounted on the base 13, and the rotating mechanism 12 is connected to the base 13 to drive the base 13 to rotate about the linearly polarized beam emission direction. The rotating mechanism 12 can be a rotary motor, and the rotating end of the rotary motor is connected to the base 13, thereby driving the base 13 to rotate. Figure 1 The lens of the terahertz emission mechanism 11 rotates around the x-axis (which can be considered the emission direction of the linearly polarized beam), and during rotation, it is necessary to ensure that the lens of the terahertz emission mechanism 11 only rotates around the x-axis and does not undergo linear displacement in the x-axis, y-axis and z-axis directions (nor will it undergo linear displacement in other directions).

[0052] Furthermore, the terahertz emission mechanism 11 includes a terahertz source capable of emitting linearly polarized beams; or, the terahertz emission mechanism 11 includes a terahertz source and a linear polarizer mounted on the terahertz source, wherein the beam emitted from the terahertz source is converted into a linearly polarized beam after passing through the linear polarizer. This arrangement is to enable the terahertz emission mechanism 11 to emit linearly polarized beams in the terahertz band. The frequency modulation range of the terahertz source is 0.1–1 THz to adapt to different specific application scenarios; preferably, the frequency modulation range of the terahertz source is 0.3–0.4 THz. In this embodiment, the terahertz emission mechanism 11 includes a terahertz source capable of emitting linearly polarized beams.

[0053] like Figure 9 As shown, a terahertz source can be a linearly distributed terahertz source at 0 degrees; as... Figure 10As shown, a terahertz source can be a linearly distributed terahertz source at 90 degrees; as Figure 11 As shown, a terahertz source can be an elliptical terahertz source at 45 degrees; as Figure 12 As shown, a terahertz source can be a circularly distributed terahertz source.

[0054] like Figure 1 and 5 As shown, in this embodiment, the reflection shaping component 2 includes an off-axis collimating mirror 21 and an even-order aspherical shaping mirror 22 arranged sequentially along the optical path propagation direction of the linearly polarized beam. Figure 8 As shown in the figure, in this embodiment, the amplitude distribution of the emitted light spot after the linearly polarized beam passes through the reflection shaping component is shown. This figure represents the amplitude distribution of the light spot after collimation and shaping. It is a flat-top light, which makes the intensity of the light spot uniformly distributed on the sample surface. If it is not shaped, the light spot is Gaussian distributed, that is, strong in the middle and weak at the edges, which makes the intensity information of the irradiated sample surface inconsistent.

[0055] like Figure 6 As shown, in another embodiment, the reflection shaping component 2 includes an axial collimating mirror, an off-axis microarray mirror group, an off-axis integrating mirror, and a planar mirror group arranged sequentially along the optical path propagation direction of the linearly polarized beam.

[0056] Regardless of the embodiment described above, the function of the reflection shaping component 2 is to reflect and shape the linearly polarized beam emitted (emitted) by the terahertz emission mechanism 11. The shaping process involves collimating the linearly polarized beam to transform the diverging Gaussian beam into a flat-topped collimated beam. The shaped beam passes through the sample under test and then reaches the terahertz receiving device 4. Furthermore, using reflective optical elements, compared to refractive optical elements, can improve imaging performance and reduce absorption loss.

[0057] In one specific embodiment, the loading device 3 includes a four-dimensional displacement stage 31 and a loading stage 32 disposed on the four-dimensional displacement stage 31, the loading stage 32 being used to carry the sample.

[0058] Specifically, the four-dimensional displacement stage 31 includes an x-axis linear displacement stage 311, a y-axis linear displacement stage 312, a z-axis linear displacement stage 313, and a y-axis rotary displacement stage 314. The four-dimensional displacement stage 31 can be electrically powered. The z-axis linear displacement stage 313 is mounted on the x-axis linear displacement stage 311, and the x-axis linear displacement stage 311 can drive the z-axis linear displacement stage 313 to perform linear reciprocating motion along the x-axis direction. The y-axis linear displacement stage 312 is mounted on the z-axis linear displacement stage 313, and the z-axis linear displacement stage 313 can drive the y-axis linear displacement stage 312 to perform linear reciprocating motion along the z-axis direction. The y-axis rotary displacement stage 314 is mounted on the y-axis linear displacement stage 312, and the y-axis linear displacement stage 312 can drive the y-axis rotary displacement stage 314 to perform linear reciprocating motion along the y-axis direction. The stage 32 is mounted on the y-axis rotary displacement stage 314, and the y-axis rotary displacement stage 314 can drive the stage 32 to perform axial rotational motion along the y-axis direction, so that the stage 32 can be located on the optical path of the linearly polarized beam.

[0059] The x-axis linear stage 311, y-axis linear stage 312, and z-axis linear stage 313 can be commercially available stepper motors or servo motors. The z-axis linear stage 313 can be a common rotary motor and its components.

[0060] like Figure 1 , 2 As shown in Figure 7, the terahertz receiving device 4 includes an off-axis three-mirror optical component 41 and a terahertz surface array detector 42 arranged sequentially along the optical path propagation direction of the linearly polarized beam. The off-axis three-mirror optical component 41 is used to focus the linearly polarized beam onto the terahertz surface array detector 42.

[0061] To ensure the accuracy of the terahertz receiver 4, the terahertz receiver 4 may include a fixed base 43, an off-axis three-mirror optical assembly 41 and a terahertz surface array detector 42 disposed on the fixed base 43, for supporting and adjusting the position of the off-axis three-mirror optical assembly 41 and the terahertz surface array detector 42 in the optical path.

[0062] Preferably, the terahertz receiving device 4 may further include a housing (not shown in the figure) covering the mounting base 43. The terahertz surface array detector 42 can be slidably mounted along the optical axis within the space enclosed by the mounting base 43 and the housing for focusing imaging of objects at different object distances. It is fixed to the mounting base 43 by common fasteners, such as screws. The terahertz surface array detector 42 is located within the absorbing space enclosed by the mounting base 43 and the housing to prevent stray light from entering the space and causing the information received by the terahertz surface array detector 42 to be affected by stray light.

[0063] Preferably, the off-axis three-mirror optical assembly 41 includes a primary mirror 411, a secondary mirror 412, and a third mirror 413 arranged sequentially along the optical path propagation direction. The off-axis three-mirror optical assembly 41 serves to reflect and focus the linearly polarized beam passing through the sample to the receiving end of the terahertz surface array detector 42. Furthermore, using reflective optical elements, compared to refractive optical elements, can improve imaging performance and reduce absorption loss. Specifically, the primary mirror 411, secondary mirror 412, and third mirror 413 can all be composed of freeform surface centers.

[0064] The terahertz surface array detector 42 is a terahertz surface array detector 42 with linear polarization detection function; or, a linear polarizer is installed at the receiving end of the terahertz surface array detector 42. In this embodiment, the terahertz surface array detector 42 is a terahertz surface array detector 42 with linear polarization detection function, and its detection response frequency range is 0.1~1THz. Depending on the specific application scenario, the array size of the detector can be selected as 32×32, 64×64, 128×128 or 256×256, and the array unit size can be uniformly 0.4×0.4mm or 0.5×0.5mm or 1×1mm. The unit size of the array is n times 1 / 2 wavelength of the frequency band of the measured signal, i.e., d=n×(1 / 2)×λ.

[0065] In one specific embodiment, the terahertz polarization imaging system further includes a host computer (not shown in the figure), which is electrically connected to the terahertz receiving device 4 and is used to receive information transmitted by the terahertz receiving device 4. The host computer can also perform calculations based on the received amplitude intensity image information to obtain the polarization image information and other information of the sample.

[0066] To provide a more detailed description of the terahertz polarization imaging system of the present invention, the present invention also provides a terahertz polarization imaging test method, which is applied to the above-mentioned terahertz polarization imaging system.

[0067] During polarization imaging detection, based on the assumption that the propagation direction of the electromagnetic wave is along the z-axis (i.e., the optical path direction when the linearly polarized beam passes through the sample), the electric field vector lies in the xy plane, and the two independent electric field components can be expressed as:

[0068]

[0069] In the formula, A x Let A be the amplitude of the electromagnetic wave in the x-direction. y Let δ be the amplitude in the y-direction, and k be the propagation constant. δ = δ x -δ y The phase difference is between the two directions. The Stokes parameter is defined as:

[0070]

[0071] Stokes parameters were measured experimentally.

[0072]

[0073] In the formula, P1(0°) is the optical power recorded in the xy plane when the angle between the horizontally polarized detector and the x-axis is 0°. P2 and P3 are similar. When measuring P4(0°, 45°), a 1 / 4 wave plate needs to be inserted in the optical path. The fast axis of the wave plate is at an angle of 0° with the x-axis, and the angle between the detector and the x-axis is 45°.

[0074] The direction angle of the polarization ellipse can be calculated based on the Stokes parameters:

[0075]

[0076] The amplitudes in both directions are:

[0077]

[0078] The phase difference between the two polarization directions is:

[0079]

[0080] Then the major axis a and minor axis b of the polarization ellipse are respectively:

[0081]

[0082] The data processing algorithm developed using the above formula, combined with host computer software, processes the acquired imaging data to obtain the intensity distribution and polarization distribution of terahertz waves in space, thereby enabling the analysis of the polarization characteristics of the sample under test and ultimately obtaining the polarization image information of the sample.

[0083] The terahertz polarization imaging system of the present invention will be described in detail below with specific examples:

[0084] Building such Figure 1 and 2 The terahertz polarization imaging system shown;

[0085] The system parameters are configured, and the frequency modulation range of the terahertz source is set from 0.1 THz to 1 THz to adapt to different detection requirements. The terahertz source generates a linearly polarized beam, or a linear polarizer is added in front of the terahertz source to generate a linearly polarized beam. The linearly polarized beam emitted from the terahertz source is fixed on an electrically driven rotary displacement stage, which can rotate the linearly polarized light 360 degrees.

[0086] The divergent terahertz Gaussian wave is homogenized into a flat-top collimated beam after passing through a total internal reflection beamforming lens, with a shaped spot size of 100×100mm. The shaped terahertz beam then reaches an off-axis three-mirror optical assembly with a focal length of 80mm and an F-number of 1, and is finally imaged onto a terahertz surface array detector.

[0087] It should be noted that this example does not have a sample during the test, which is equivalent to a blank group. The data obtained by the terahertz surface array detector in this example are as follows: Figure 13 and 14 The amplitude distribution data at 0° and 90° shown were obtained after calculation. Figure 15 and 16 The magnitude distributions in the Ex and Ey directions were further calculated to obtain... Figure 17 The polarization state distribution, in Figure 17 In this context, an axial ratio > 10 dB is defined as a linear polarization state, an axial ratio of 3 to 10 dB is defined as an elliptically polarized state, and an axial ratio < 3 dB is defined as a circularly polarized state. Figure 18 It is a test of the polarization state in polar coordinates at the center position of the light spot using a linear polarization detector of a single unit.

[0088] In summary, the beneficial effects of the terahertz polarization imaging system of the present invention are as follows:

[0089] (1) It can obtain polarization information of the sample in the terahertz band and provide a more comprehensive analysis of sample characteristics.

[0090] (2) It adopts a transmission optical path to achieve non-destructive testing, which is suitable for industrial online testing and biomedical imaging.

[0091] (3) High-resolution imaging based on terahertz waves improves imaging quality and detection accuracy.

[0092] (4) By rotating the terahertz mechanism, comprehensive measurement of different polarization directions of the sample can be achieved, enhancing the applicability and flexibility of the system.

[0093] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0094] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style of the specification is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A terahertz polarization imaging system, characterized in that, It includes a terahertz emission device for emitting linearly polarized beams, and a reflection shaping component, a carrier device, and a terahertz receiving device arranged sequentially along the optical path propagation direction of the linearly polarized beams. The terahertz emission device includes a terahertz emission mechanism that can rotate about the direction of linearly polarized beam emission, and the terahertz emission mechanism is used to emit a linearly polarized beam. The reflection shaping component is used to reflect linearly polarized beams and collimate and shape them. The sample carrier is used to carry the sample and position the sample in the optical path reflected by the reflective shaping component. The terahertz receiving device is used to receive linearly polarized beams, and the image information received by the terahertz receiving device is amplitude intensity image information containing sample polarization information; The terahertz receiving device also includes a fixed base and a terahertz surface array detector arranged along the optical path propagation direction of the linearly polarized beam. The terahertz surface array detector is slidably mounted on the fixed base along the optical axis, used for focusing imaging of objects at different object distances, and is fixed to the fixed base by a fixing component.

2. The terahertz polarization imaging system according to claim 1, characterized in that, The terahertz emission device includes a rotating mechanism and a base. The terahertz emission mechanism is mounted on the base, and the rotating mechanism is connected to the base to drive the base to rotate about the linearly polarized beam emission direction as an axis.

3. The terahertz polarization imaging system according to claim 1, characterized in that, The terahertz emission mechanism includes a terahertz source capable of emitting linearly polarized beams; or, The terahertz emission mechanism includes a terahertz source and a linear polarizer mounted on the terahertz source. The beam emitted from the terahertz source is converted into a linearly polarized beam after passing through the linear polarizer.

4. The terahertz polarization imaging system according to claim 1, characterized in that, The reflection shaping assembly includes an off-axis collimating mirror and an even-order aspherical shaping mirror arranged sequentially along the optical path propagation direction of the linearly polarized beam; or... The reflection shaping component includes an axial collimating mirror, an off-axis microarray mirror group, an off-axis integrating mirror, and a plane mirror group arranged sequentially along the optical path propagation direction of the linearly polarized beam.

5. The terahertz polarization imaging system according to claim 1, characterized in that, The loading device includes a four-dimensional displacement stage and a loading stage disposed on the four-dimensional displacement stage, the loading stage being used to carry the sample.

6. The terahertz polarization imaging system according to claim 5, characterized in that, The four-dimensional displacement stage includes an x-axis linear displacement stage, a y-axis linear displacement stage, a z-axis linear displacement stage, and a y-axis rotary displacement stage.

7. The terahertz polarization imaging system according to claim 1, characterized in that, The terahertz receiving device includes an off-axis three-mirror optical assembly arranged along the optical path propagation direction of the linearly polarized beam. The off-axis three-mirror optical assembly is used to converge the linearly polarized beam to the terahertz surface array detector.

8. The terahertz polarization imaging system according to claim 7, characterized in that, The off-axis three-mirror optical assembly includes a primary mirror, a secondary mirror, and a third mirror arranged sequentially along the optical path propagation direction.

9. The terahertz polarization imaging system according to claim 7, characterized in that, The terahertz surface array detector is a terahertz surface array detector with linear polarization detection function; or, a linear polarizer is installed at the receiving end of the terahertz surface array detector.

10. The terahertz polarization imaging system according to claim 1, characterized in that, The terahertz polarization imaging system also includes a host computer, which is electrically connected to the terahertz receiving device and is used to receive information transmitted by the terahertz receiving device.

Images