Terahertz polarization imaging system

Abstract

The invention discloses a terahertz polarization imaging system which comprises a terahertz emitting device used for emitting linear polarization beams, and a reflection shaping assembly, a carrying device and a terahertz receiving device which are sequentially arranged along the light path propagation direction of the linear polarization beams. The terahertz emitting device comprises a terahertz emitting mechanism capable of rotating by taking the emitting direction of the linear polarization beam as an axis, and the terahertz emitting mechanism is used for emitting the linear polarization beam; the reflection shaping assembly is used for reflecting the linear polarization beam and performing collimation shaping; the loading device is used for loading a sample and enabling the sample to be positioned on a light path reflected by the reflecting and shaping assembly; and the terahertz receiving device is used for receiving the linear polarization beam. The terahertz polarization imaging system can obtain 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] The invention belongs to the technical field of terahertz, and in particular relates to a terahertz polarization imaging system. Background Art

[0002] Terahertz (THz) wave imaging technology is an emerging nondestructive testing method. Due to its unique position in the electromagnetic spectrum, between microwaves and infrared, it has the advantages of strong penetration, non-ionization, and sensitivity to certain materials. Terahertz nondestructive testing systems have shown broad application potential in the fields of materials science, biomedical imaging, and safety inspection. However, existing terahertz nondestructive testing systems mainly focus on obtaining the amplitude intensity information of the sample being tested, but lack the measurement and analysis of polarization information.

[0003] Polarization information is one of the important properties of electromagnetic waves, which can provide complementary information about the structure, composition and surface characteristics of samples. 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. Therefore, terahertz imaging systems that lack polarization information have poor performance in the detection of high-transmittance samples, limiting their detection capabilities in certain application scenarios.

[0004] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0005] The object of the present invention is to provide a terahertz polarization imaging system, which can obtain the polarization information of a sample in the terahertz band and can be used to achieve high-resolution polarization imaging.

[0006] In order to achieve the above-mentioned object, a technical solution provided by a specific embodiment of the present invention is as follows: a terahertz polarization imaging system, comprising a terahertz emitting device for emitting a linearly polarized beam, and a reflection shaping component, a loading device and a terahertz receiving device sequentially arranged along the optical path propagation direction of the linearly polarized beam;

[0007] The terahertz emitting device comprises a terahertz emitting mechanism that can rotate with the linear polarization beam emitting direction as an axis, and the terahertz emitting mechanism is used to emit a linear polarization beam;

[0008] The reflection shaping component is used to reflect the linearly polarized beam and perform collimation shaping;

[0009] The object-carrying device is used to carry the sample and place the sample on the light path reflected by the reflection shaping component;

[0010] The terahertz receiving device is used for receiving a linearly polarized beam.

[0011] In one or more embodiments of the present invention, the terahertz emitting device includes a rotating mechanism and a base, the terahertz emitting mechanism is installed on the base, and the rotating mechanism is connected to the base to drive the base to rotate around the linear polarization beam emitting direction as the axis.

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

[0013] The terahertz emission mechanism comprises a terahertz source and a linear polarizer installed on the terahertz source. The beam emitted by 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 comprises an off-axis collimating reflector and an even-order aspheric shaping mirror sequentially arranged along the optical path propagation direction of the linearly polarized beam; or,

[0015] The reflection shaping component comprises an axis collimating reflector, an off-axis micro-array reflector group, an off-axis integrating reflector, and a plane reflector group which are sequentially arranged along the optical path propagation direction of the linear polarization beam.

[0016] In one or more embodiments of the present invention, the loading device includes a four-dimensional translation stage and an loading platform disposed on the four-dimensional translation stage, and the loading platform is used to load the sample.

[0017] In one or more embodiments of the present invention, the four-dimensional translation stage includes an x-axis linear translation stage, a y-axis linear translation stage, a z-axis linear translation stage, and a y-axis rotational translation 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 in sequence along the optical propagation direction of the linearly polarized beam, and 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 in sequence along the propagation direction of the light path.

[0020] In one or more embodiments of the present invention, the terahertz surface array detector is a terahertz surface array detector with a 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 emitting device. The linearly polarized beam is reflected and collimated by a reflection shaping component, passes through a sample on a loading device, and is then received by a terahertz receiving device, thereby obtaining imaging information of the terahertz wave under polarization. In addition, the terahertz source can rotate around the emission direction of the linearly polarized beam, that is, the terahertz source is rotated at 0 degrees, 45 degrees, and 90 degrees. The terahertz receiving device collects imaging effects under different polarizations, and the Stokes parameters can be used to calculate the sample polarization imaging information and the transmission amplitude intensity imaging information under the polarization state. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 is a three-dimensional schematic diagram of a terahertz polarization imaging system in one embodiment of the present invention;

[0025] Figure 2 1 is a top view of a terahertz polarization imaging system (including an optical path) in one embodiment of the present invention;

[0026] Figure 3 A three-dimensional schematic diagram of the optical path of a terahertz polarization imaging system in one embodiment of the present invention;

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

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

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

[0030] Figure 7 A top view of the optical path of an off-axis three-mirror optical assembly in one embodiment of the present invention;

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

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

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

[0034] Fig.11 is a schematic diagram of an elliptically distributed terahertz source in one embodiment of the present invention;

[0035] Fig.12 A schematic diagram of a circularly distributed terahertz source in one embodiment of the present invention;

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

[0037] Fig.14 This is a 90-degree position imaging diagram obtained by a terahertz surface array detector in an example of the present invention;

[0038] Fig.15 This is a diagram showing the calculation result of the amplitude distribution in the Ey direction obtained by the terahertz surface array detector in an example of the present invention;

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

[0040] Fig.17 An axial ratio diagram obtained by a terahertz surface array detector in an example of the present invention;

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

[0042] Description of main reference numerals:

[0043] 1. Terahertz emitting device; 11. Terahertz emitting mechanism; 12. Rotating mechanism; 13. Base; 2. Reflection shaping assembly; 21. Off-axis collimating reflector; 22. Even-order aspheric shaping mirror; 3. Object-carrying device; 31. Four-dimensional translation stage; 311. X-axis linear translation stage; 312. Y-axis linear translation stage; 313. Z-axis linear translation stage; 314. Y-axis rotation translation stage; 32. Object-carrying stage; 4. Terahertz receiving device; 41. Off-axis three-reflection optical assembly; 411. Primary mirror; 412. Secondary mirror; 413. Triple mirror; 42. Terahertz surface array detector; 43. Fixed seat. Specific embodiments

[0044] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0045] like Figures 1 to 4 As shown, a terahertz polarization imaging system in one embodiment of the present invention comprises a terahertz emitting device 1 for emitting a linearly polarized beam, and a reflection shaping component 2, a carrier device 3 and a terahertz receiving device 4 which are sequentially arranged along the optical path propagation direction of the linearly polarized beam; the terahertz emitting device 1 comprises a terahertz emitting mechanism 11 which can rotate with the linearly polarized beam emitting direction as an axis, and the terahertz emitting mechanism 11 is used to emit a linearly polarized beam; the reflection shaping component 2 is used to reflect the linearly polarized beam and perform collimation shaping; the carrier device 3 is used to carry a sample and place 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, which can provide complementary information about the structure, composition and surface characteristics of the sample. 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 a frequency range of 0.1THz to 10THz and a wavelength of approximately 0.03 to 3mm, which is between microwaves and infrared.

[0047] It can be understood that the linearly polarized beam (also called linearly polarized terahertz wave) emitted by the terahertz emitting device 1, after being reflected, collimated and shaped by the reflection shaping component 2, will illuminate and pass through the sample (also called the measured sample) located on the loading 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 sample polarization information. Since the terahertz emitting device 1 is a terahertz wave, the above-mentioned sample polarization information is the polarization information of the sample in the terahertz band.

[0048] In addition, due to Figures 1 to 4 No samples are set in Figure 1 and 2 The position of the object carrying device 3 (including the object carrying platform 32) is slightly deviated, that is, Figure 1 and 2The position of the stage 32 in the middle loading device 3 has some deviations. During actual testing, it is also 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 on the optical path.

[0049] The amplitude intensity image information containing the sample polarization information can directly obtain information such as intensity distribution, and can also be used to obtain polarization image information after subsequent calculation and processing, so as to realize the polarization characteristic analysis of the sample under test and realize high-resolution polarization imaging of the sample. Polarization imaging can not only improve the contrast and resolution of imaging, but also provide more physical and chemical information about the sample, thereby realizing more accurate non-destructive testing and evaluation.

[0050] In this embodiment, the terahertz emitting device 1 includes a terahertz emitting mechanism 11 that can rotate with the linear polarization beam emitting direction as the axis, that is, the imaging effects under different polarizations are collected at 0 degrees, 45 degrees, and 90 degrees by rotating the terahertz emitting mechanism, so as to facilitate the subsequent calculation and processing of the polarization image information using the Stokes parameters.

[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. The rotating mechanism 12 is connected to the base 13 to drive the base 13 to rotate with the linear polarization beam emission direction as the axis. The rotating mechanism 12 can be a rotating motor, and the rotating end of the rotating motor is connected to the base 13, thereby driving the base 13 to rotate, that is, the terahertz emission mechanism 11 can be installed on the base 13. Figure 1 The x-axis direction (which can be considered as the emission direction of the linearly polarized beam) is the axis of rotation, and during rotation, it is necessary to ensure that the lens of the terahertz emission mechanism 11 only rotates around the x-axis direction, and no linear displacement in the x-axis, y-axis and z-axis directions (nor linear displacement in other directions) occurs.

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

[0053] like Fig. 9 As shown, the terahertz source can be a linearly distributed terahertz source at 0 degrees; Fig.10As shown, the terahertz source can be a linearly distributed terahertz source at 90 degrees; Fig.11 As shown, the terahertz source can be an elliptically distributed terahertz source at 45 degrees; Fig.12 As shown, the 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 reflector 21 and an even-order aspheric shaping mirror 22 which are sequentially arranged along the optical path propagation direction of the linearly polarized beam. Figure 8 As shown, in this embodiment, the linearly polarized beam is emitted after the reflection shaping component. The figure represents the amplitude distribution of the light spot after collimation shaping. It is a flat-top light, so that the intensity of the light spot is evenly distributed on the sample surface. If it is not shaped, the light spot is a Gaussian distribution, that is, strong in the middle and weak at the edge, which makes the intensity information irradiated to the sample surface inconsistent.

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

[0056] Regardless of which embodiment of the above, the reflective shaping component 2 is used to reflect and shape the linearly polarized beam emitted (emitted) by the terahertz emission mechanism 11. The shaping process is to collimate the linearly polarized beam, which is used to shape the divergent Gaussian beam into a flat-top collimated beam. The shaped beam passes through the sample to be tested and then reaches the terahertz receiving device 4. In addition, the use of reflective optical elements can improve the imaging effect and reduce the absorption loss compared to refractive optical elements.

[0057] In a specific embodiment, the loading device 3 includes a four-dimensional translation stage 31 and a loading stage 32 disposed on the four-dimensional translation stage 31 , and the loading stage 32 is used for loading the sample.

[0058] Specifically, the four-dimensional translation stage 31 includes an x-axis linear translation stage 311 , a y-axis linear translation stage 312 , a z-axis linear translation stage 313 and a y-axis rotational translation stage 314 . The four-dimensional translation stage 31 can be an electric four-dimensional translation stage 31, the z-axis linear translation stage 313 is installed on the x-axis linear translation stage 311, and the x-axis linear translation stage 311 can drive the z-axis linear translation stage 313 to perform linear linear reciprocating motion along the x-axis direction; the y-axis linear translation stage 312 is installed on the z-axis linear translation stage 313, and the z-axis linear translation stage 313 can drive the y-axis linear translation stage 312 to perform linear linear reciprocating motion along the z-axis direction; the y-axis rotational translation stage 314 is installed on the y-axis linear translation stage 312, and the y-axis linear translation stage 312 can drive the y-axis rotational translation stage 314 to perform linear linear reciprocating motion along the y direction; the stage 32 is installed on the y-axis rotational translation stage 314, and the y-axis rotational translation 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 displacement stage 311, the y-axis linear displacement stage 312, and the z-axis linear displacement stage 313 may be stepper motors or servo motors directly available on the market, etc. The z-axis linear displacement stage 313 may be a common rotary motor and its components available on the market.

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

[0061] In order to ensure the accuracy of the terahertz receiving device 4, the terahertz receiving device 4 may include a fixed base 43, and the off-axis three-mirror optical component 41 and the terahertz surface array detector 42 are arranged on the fixed base 43, which is used to support and adjust the position of the off-axis three-mirror optical component 41 and the terahertz surface array detector 42 in the optical path.

[0062] Preferably, the terahertz receiving device 4 may further include a shell (not shown in the figure) covering the fixing seat 43, and the terahertz surface array detector 42 may be slidably installed along the optical axis in the space enclosed by the fixing seat 43 and the shell, and is used to focus the imaging of objects at different object distances, and is fixed to the fixing seat 43 by common fixing parts, which may be screws or the like; the terahertz surface array detector 42 is located in the absorbing space enclosed by the fixing seat 43 and the shell to prevent stray light from entering the space, causing the information received by the terahertz surface array detector 42 to be affected by the 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 in sequence along the propagation direction of the optical path. The off-axis three-mirror optical assembly 41 plays a role of reflection and focusing, focusing the linearly polarized beam passing through the sample to the receiving end of the terahertz surface array detector 42. In addition, the use of reflective optical elements can improve the imaging effect and reduce the absorption loss compared to refractive optical elements. Specifically, the primary mirror 411, the secondary mirror 412 and the third mirror 413 can all be composed of free-form surface centers.

[0064] The terahertz surface array detector 42 is a terahertz surface array detector 42 with a 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 a linear polarization detection function, and its detection response frequency range is 0.1 to 1 THz. According to the specific application scenario, the array scale of the detector can be selected as 32×32, 64×64, 128×128 or 256×256, and the array unit size can be unified as 0.4×0.4mm or 0.5×0.5mm or 1×1mm, and the unit size of the array is n times 1 / 2 wavelength of the measured signal frequency band, that is, d=n×(1 / 2)×λ.

[0065] In a 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 amplitude intensity image information that can be received, so as to obtain polarization image information and other information of the sample.

[0066] In order to introduce the terahertz polarization imaging system of the present invention in more detail, the present invention also provides a terahertz polarization imaging test method, which is applied to the above-mentioned terahertz polarization imaging system.

[0067] When performing polarization imaging detection, the propagation direction of the electromagnetic wave is assumed to be along the z-axis (i.e., the direction of the light path when the linearly polarized beam passes through the sample), and the electric field vector is located in the xy plane. The two independent electric field components can be expressed as:

[0068]

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

[0070]

[0071] Experimentally measure the Stokes parameters:

[0072]

[0073] Wherein, 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°, and P2 and P3 are similar. When measuring P4 (0°, 45°), it is necessary to insert a 1 / 4 wave plate in the optical path, the angle between the fast axis of the wave plate and the x-axis is 0°, and the angle between the detector and the x-axis is 45°.

[0074] According to the Stokes parameters, the direction angle of the polarization ellipse can be calculated:

[0075]

[0076] The amplitudes in both directions are:

[0077]

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

[0079]

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

[0081]

[0082] The data processing algorithm developed through the above formula is combined with the host computer software to process the collected imaging data to obtain the intensity distribution and polarization distribution of the terahertz wave in space, realize the polarization characteristic analysis of the measured sample, and finally obtain the polarization image information of the sample.

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

[0084] Build as Figure 1 and 2 The terahertz polarization imaging system shown;

[0085] The system parameters are configured to set the frequency modulation range of the terahertz source to 0.1THz to 1THz to meet 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 by the terahertz source is fixed on an electric rotation stage, which can rotate the linearly polarized light 360 degrees.

[0086] The divergent terahertz Gaussian wave passes through the total reflection beam shaping lens to achieve a homogenized flat-top collimated beam with a shaped spot size of 100×100mm. The shaped terahertz beam reaches the off-axis three-mirror optical component, which has a focal length of 80mm and an F number of 1, and is finally imaged on the terahertz surface array detector.

[0087] It should be noted that there is no sample in the test process of this example, which is equivalent to a blank group. The data obtained by the terahertz surface array detector in this example are as follows: Fig.13 and 14 The amplitude distribution data of 0° and 90° shown in the figure are calculated and obtained. Fig.15 and 16 The amplitude distribution in the Ex and Ey directions was further calculated. Fig.17 The polarization state distribution of Fig.17 In the definition, an axial ratio > 10dB is defined as a linear polarization state, an axial ratio of 3 to 10dB is defined as an elliptical polarization state, and an axial ratio < 3dB is defined as a circular polarization state. Fig.18 It uses a unit linear polarization detector to test the polarization state of the light spot center under polar coordinates.

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

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

[0090] (2) It adopts a transmissive 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 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 the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0094] In addition, it should be understood that although the present specification is described according to embodiments, not every embodiment contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may 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 emitting device for emitting a linearly polarized beam, and a reflection shaping component, a loading device and a terahertz receiving device which are sequentially arranged along the optical path propagation direction of the linearly polarized beam; The terahertz emitting device comprises a terahertz emitting mechanism that can rotate with the linear polarization beam emitting direction as an axis, and the terahertz emitting mechanism is used to emit a linear polarization beam; The reflection shaping component is used to reflect the linearly polarized beam and perform collimation shaping; The object-carrying device is used to carry the sample and place the sample on the light path reflected by the reflection shaping component; The terahertz receiving device is used for receiving a linearly polarized beam.

2. The terahertz polarization imaging system according to claim 1, characterized in that: The terahertz emission device comprises a rotating mechanism and a base. The terahertz emission mechanism is installed on the base. The rotating mechanism is connected to the base to drive the base to rotate with the linear polarization beam emission direction as the 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 a linearly polarized beam; or, The terahertz emission mechanism comprises a terahertz source and a linear polarizer installed on the terahertz source. The beam emitted by 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 component comprises an off-axis collimating reflector and an even-order aspheric shaping mirror which are sequentially arranged along the optical path propagation direction of the linearly polarized beam; or, The reflection shaping component comprises an axis collimating reflector, an off-axis micro-array reflector group, an off-axis integrating reflector, and a plane reflector group which are sequentially arranged along the optical path propagation direction of the linear polarization beam.

5. The terahertz polarization imaging system according to claim 1, characterized in that: The object carrying device comprises a four-dimensional displacement platform and an object carrying platform arranged on the four-dimensional displacement platform, and the object carrying platform is used for carrying samples.

6. The terahertz polarization imaging system according to claim 5, characterized in that: The four-dimensional translation stage comprises an x-axis linear translation stage, a y-axis linear translation stage, a z-axis linear translation stage and a y-axis rotational translation stage.

7. The terahertz polarization imaging system according to claim 1, characterized in that: The terahertz receiving device comprises an off-axis three-mirror optical component and a terahertz surface array detector which are sequentially arranged 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.

8. The terahertz polarization imaging system according to claim 7, characterized in that: The off-axis three-mirror optical assembly comprises a primary mirror, a secondary mirror and a tertiary mirror which are arranged in sequence along the propagation direction of the light path.

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 a 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