A terahertz time-domain spectroscopy system with multiplexed probes for testing modules

Abstract

This invention relates to the field of optoelectronic technology, specifically to a terahertz time-domain spectroscopy system with a multiplexed test module and probe. It includes a femtosecond laser, outputting pump and probe light; a terahertz emitting photoconductive antenna, receiving the pump light to generate an incident terahertz wave; a test module, receiving the incident terahertz wave and generating an output terahertz wave carrying information about the sample under test; the test module can be configured as a reflection measurement module, a transmission measurement module, or a focused light attenuation total internal reflection measurement module based on test requirements; and a terahertz receiving photoconductive antenna, receiving the probe light and the output terahertz wave carrying information about the sample under test. This invention provides different detection modules according to test requirements, reducing resource waste; it is simple to operate and can be used immediately after replacement; it does not require adjustment of internal components, thus not affecting the stability of the terahertz detection system; it is highly adaptable, and a suitable probe can be designed according to the optical path of the device.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic technology, and more specifically to a terahertz time-domain spectroscopy system. Background Technology

[0002] At present, both domestic and foreign countries attach great importance to the development of terahertz technology. Since terahertz waves have good transmission and reflection characteristics, terahertz detection systems can measure the absorption spectrum of the sample by penetrating the sample through the transmission characteristics, and measure the internal layer distribution of the sample by the reflection characteristics of terahertz waves.

[0003] The manufacturing technology of existing terahertz detection systems is not perfect, making these systems expensive. Therefore, the traditional single-device-one-use approach results in significant resource waste, with a single photoconductive antenna costing hundreds of thousands of yuan. While existing single-module multi-functional terahertz detection systems on the market can perform multiple functions, these systems are often complex in structure and difficult to operate. Using different functions often requires users to manually adjust internal components to change the system's optical path, which reduces the stability of the terahertz detection system during manual adjustments and significantly impacts its working efficiency. Summary of the Invention

[0004] The purpose of this invention is to provide a terahertz time-domain spectroscopy system that reuses the probe of the test module, thereby solving the above-mentioned technical problems;

[0005] A terahertz time-domain spectroscopy system with multiplexed probes for testing modules includes,

[0006] A femtosecond laser, wherein the femtosecond laser outputs a pump beam and a probe beam;

[0007] A terahertz photoconductive antenna is connected to the femtosecond laser via a first optical fiber to receive the pump light and generate an incident terahertz wave excited by the pump light.

[0008] A replaceable test module, wherein the test module receives the incident terahertz wave and generates an output terahertz wave carrying information about the sample to be tested, and the test module is configured as a reflection measurement module, a transmission measurement module, or a focused light attenuation total internal reflection measurement module based on the test requirements.

[0009] A terahertz receiving photoconductive antenna is set up in correspondence with the test module to receive the probe light and the output terahertz wave carrying the information of the sample to be tested, and converts the optical signal into an electrical signal to output the information of the sample to be tested.

[0010] Preferably, the reflection measurement module includes,

[0011] The first off-axis parabolic mirror reflects the incident terahertz wave emitted by the terahertz transmitting photoconductive antenna into a parallel terahertz wave along the positive Y-axis direction.

[0012] A first elliptical reflector is disposed on the positive Y-axis direction of the first off-axis parabolic mirror, and there is a first distance between the center of the first elliptical reflector and the center of the first off-axis parabolic mirror, for reflecting terahertz waves from the first elliptical reflector in the negative X-axis direction.

[0013] The second off-axis parabolic mirror is disposed in the negative X-axis direction of the first elliptical mirror, and there is a second distance between the center of the second off-axis parabolic mirror and the center of the first elliptical mirror, for reflecting the terahertz wave from the first elliptical mirror to the sample to be tested.

[0014] The sample to be tested is located in a first direction between the negative Y-axis and the positive Z-axis of the second off-axis parabolic mirror, and there is a third distance between the sample to be tested and the center of the second off-axis parabolic mirror.

[0015] A third off-axis parabolic mirror is disposed in a second direction between the positive Z-axis direction and the positive Y-axis direction of the sample to be tested. A fourth distance exists between the third off-axis parabolic mirror and the sample to be tested. The third off-axis parabolic mirror is used to reflect the diverging terahertz wave from the sample to be tested into a parallel terahertz wave propagating along the negative X-axis direction.

[0016] The second elliptical reflector is located in the negative X-axis direction of the third off-axis parabolic mirror. There is a fifth distance between the centers of the second elliptical reflector and the third off-axis parabolic mirror. It is used to reflect terahertz waves from the third off-axis parabolic mirror in the negative Y-axis direction.

[0017] A fourth off-axis parabolic mirror is disposed on the negative Y-axis direction of the second elliptical mirror. There is a sixth distance between the center of the fourth off-axis parabolic mirror and the center of the second elliptical mirror. The fourth off-axis parabolic mirror is used to reflect and focus the terahertz wave from the second elliptical mirror onto the terahertz receiving photoconductive antenna.

[0018] Preferably, the transmission measurement module includes,

[0019] The fifth off-axis parabolic mirror reflects the incident terahertz wave emitted by the terahertz transmitting photoconductive antenna into a parallel terahertz wave along the positive Y-axis direction.

[0020] The third elliptical reflector is located on the positive Y-axis direction of the fifth off-axis parabolic mirror. There is a seventh distance between the centers of the third elliptical reflector and the fifth off-axis parabolic mirror. It is used to reflect terahertz waves from the fifth elliptical reflector in the negative X-axis direction.

[0021] The sixth off-axis parabolic mirror is located on the negative X-axis direction of the third elliptical mirror. There is an eighth distance between the center of the sixth off-axis parabolic mirror and the center of the third elliptical mirror. It is used to reflect the terahertz wave from the third elliptical mirror to the sample to be tested.

[0022] The sample to be tested is located on the negative Y-axis direction of the sixth off-axis parabolic mirror, and there is a ninth distance between the sample to be tested and the center of the sixth off-axis parabolic mirror;

[0023] A seventh off-axis parabolic mirror is disposed in the negative Y-axis direction of the sample to be tested. There is a tenth distance between the seventh off-axis parabolic mirror and the sample to be tested. The seventh off-axis parabolic mirror is used to reflect the divergent terahertz wave from the sample to be tested into a parallel terahertz wave propagating in the negative X-axis direction.

[0024] The fourth elliptical reflector is located in the negative X-axis direction of the seventh off-axis parabolic mirror. There is an eleventh distance between the center of the fourth elliptical reflector and the center of the seventh off-axis parabolic mirror. It is used to reflect terahertz waves from the seventh off-axis parabolic mirror in the negative Z-axis direction.

[0025] The eighth off-axis parabolic mirror is located on the positive Z-axis direction of the fourth elliptical mirror. There is a twelfth distance between the center of the eighth off-axis parabolic mirror and the center of the fourth elliptical mirror. The eighth off-axis parabolic mirror is used to reflect and focus the terahertz wave from the fourth elliptical mirror onto the terahertz receiving photoconductive antenna.

[0026] Preferably, the focused light attenuation total internal reflection measurement module includes,

[0027] The ninth off-axis parabolic mirror reflects the incident terahertz wave emitted by the terahertz transmitting photoconductive antenna into a parallel terahertz wave along the positive Z-axis direction.

[0028] The tenth off-axis parabolic mirror is located in the positive Z-axis direction of the ninth off-axis parabolic mirror. There is a thirteenth distance between the centers of the tenth off-axis parabolic mirror and the ninth off-axis parabolic mirror. It is used to reflect terahertz waves from the ninth off-axis parabolic mirror in the negative X-axis direction.

[0029] A silicon prism is positioned on the negative X-axis direction of the tenth off-axis parabolic mirror, and the sample to be tested is placed on the silicon prism.

[0030] The eleventh off-axis parabolic mirror is located on the negative X-axis direction of the silicon prism. There is a fourteenth distance between the centers of the eleventh off-axis parabolic mirror and the tenth off-axis parabolic mirror. The eleventh off-axis parabolic mirror is used to reflect the terahertz waves diverging from the silicon prism into parallel terahertz waves propagating along the negative Y-axis direction.

[0031] The twelfth off-axis parabolic mirror is located on the negative Y-axis direction of the eleventh off-axis parabolic mirror. There is a fifteenth distance between the centers of the twelfth off-axis parabolic mirror and the eleventh off-axis parabolic mirror. The twelfth off-axis parabolic mirror is used to reflect and focus the terahertz wave from the eleventh off-axis parabolic mirror onto the terahertz receiving photoconductive antenna.

[0032] Preferably, the test module has a preset Z-axis length, determines the third distance based on the focal length of the second off-axis parabolic mirror, and determines the fourth distance based on the focal length of the third off-axis parabolic mirror. The Z-axis length of the test module is the third distance multiplied by the cosine of the angle between the terahertz wave reflected by the second off-axis parabolic mirror and the Z-axis, plus the fourth distance to form the cosine of the angle between the terahertz wave received by the third off-axis parabolic mirror and the Z-axis.

[0033] Preferably, the test module has a preset Y-axis length, determines the ninth distance based on the focal length of the sixth off-axis parabolic mirror, and determines the tenth distance based on the focal length of the seventh off-axis parabolic mirror. The Y-axis length of the test module is the ninth distance plus the tenth distance.

[0034] Preferably, the sixth distance and the fifteenth distance are determined based on the Y-axis length of the test module, wherein the fifteenth distance is the ninth distance plus the tenth distance minus the seventh distance.

[0035] Preferably, the test module has a preset X-axis length, and the fourteenth distance is determined based on the size of the silicon prism, with the fourteenth distance serving as the X-axis length of the test module.

[0036] Preferably, the X-axis length of the test module is used as the length of the second distance plus the fifth distance and the length of the eighth distance plus the eleventh distance.

[0037] Preferably, the terahertz receiving photoconductive antenna is connected to the femtosecond laser via a second optical fiber and a third optical fiber, receives the probe light and the output terahertz wave carrying information of the sample to be tested, and converts the optical signal into an electrical signal to output the information of the sample to be tested; an optical delay line for changing the optical path of the probe light is provided between the second optical fiber and the third optical fiber.

[0038] The beneficial effects of this invention are as follows: By adopting the above technical solutions, this invention provides different detection modules according to testing requirements, reducing resource waste; it is simple to operate and can be used immediately after replacement; it does not require adjustment of internal components and will not affect the stability of the terahertz detection system; it is highly adaptable and can design suitable probes according to the optical path of the device. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of a terahertz time-domain spectroscopy system in an embodiment of the present invention;

[0040] Figure 2 This is a schematic diagram of the reflection test module in an embodiment of the present invention;

[0041] Figure 3 This is a schematic diagram of the transmission test module in an embodiment of the present invention;

[0042] Figure 4 This is a schematic diagram of the attenuation full emission test module in an embodiment of the present invention. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0045] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the scope of the invention.

[0046] A terahertz time-domain spectroscopy system that reuses probes in a test module, such as Figure 1 As shown, including,

[0047] A femtosecond laser 101 outputs a pump beam and a probe beam;

[0048] A terahertz transmitting photoconductive antenna 106 is connected to a femtosecond laser 101 via a first optical fiber 102 to receive pump light and generate incident terahertz waves excited by the pump light.

[0049] The replaceable test module 108 receives the incident terahertz wave and generates an output terahertz wave carrying information about the sample to be tested. The test module 108 is configured as a reflection measurement module, a transmission measurement module, or a focused light attenuation total internal reflection (ATR) measurement module based on the test requirements.

[0050] A terahertz receiving photoconductive antenna 107 is set up in correspondence with the test module 108 to receive the probe light and the output terahertz wave carrying the information of the sample to be tested, and converts the optical signal into an electrical signal to output the information of the sample to be tested.

[0051] Specifically, the system of this invention adopts a multi-module configuration, enabling multiple uses from a single unit. Different detection modules are provided according to testing requirements, reducing resource waste. Operation is simple, and modules can be easily swapped out. No internal component adjustments are needed, ensuring the stability of the terahertz detection system. It is highly adaptable, allowing for the design of suitable probes based on the optical path of the device. For researchers considering using multiplexed probes, this is a simple, ideal, and feasible design method, providing customers with more options while saving costs. In existing technologies using independent probes, adding a measurement method requires adding a photoconductive antenna and optical components costing over 100,000 yuan. The superior multiplexed probe design method of this invention only requires adding optical components and configuring the corresponding probe for each measurement method. Using this method, the introduction of total internal reflection elements avoids high-frequency absorption by lenses, and the fewer inserted components, the shorter optical path, and the lower introduced losses.

[0052] Preferably, the present invention can achieve switching between three measurement modes using only a pair of antennas.

[0053] In a preferred embodiment, such as Figure 2 As shown, the reflection measurement module includes,

[0054] The first off-axis parabolic mirror 2 reflects the incident terahertz wave emitted by the terahertz transmitting photoconductive antenna 106 into a parallel terahertz wave along the positive Y-axis direction.

[0055] The first elliptical reflector 3 is located in the positive Y-axis direction of the first off-axis parabolic mirror 2, and there is a first distance between the center of the first elliptical reflector 3 and the center of the first off-axis parabolic mirror 2, for reflecting terahertz waves from the first elliptical reflector 3 in the negative X-axis direction.

[0056] The second off-axis parabolic mirror 4 is located in the negative X-axis direction of the first elliptical mirror 3. There is a second distance between the center of the second off-axis parabolic mirror 4 and the center of the first elliptical mirror 3. It is used to reflect the terahertz wave from the first elliptical mirror 3 to the sample to be tested.

[0057] The sample to be tested 9 is located in a first direction between the negative Y-axis and the positive Z-axis of the second off-axis parabolic mirror 4, and has a preset angle with the Z-axis and Y-axis. There is a third distance between the center of the sample to be tested 9 and the center of the second off-axis parabolic mirror 4.

[0058] The third off-axis parabolic mirror 5 is located in a second direction between the positive Z-axis direction and the positive Y-axis direction of the sample to be tested. The third off-axis parabolic mirror 5 and the sample to be tested have a fourth distance. The third off-axis parabolic mirror 5 is used to reflect the divergent terahertz wave from the sample to be tested 9 into a parallel terahertz wave that propagates along the negative X-axis direction.

[0059] The second elliptical mirror 6 is located in the negative X-axis direction of the third off-axis parabolic mirror 5. There is a fifth distance between the centers of the second elliptical mirror 6 and the third off-axis parabolic mirror 5. It is used to reflect terahertz waves from the third off-axis parabolic mirror 5 in the negative Y-axis direction.

[0060] The fourth off-axis parabolic mirror 7 is located on the negative Y-axis direction of the second elliptical mirror 6. There is a sixth distance between the center of the fourth off-axis parabolic mirror 7 and the center of the second elliptical mirror 6. The fourth off-axis parabolic mirror 7 is used to reflect and focus the terahertz wave from the second elliptical mirror 6 onto the terahertz receiving photoconductive antenna 107.

[0061] Specifically, the terahertz transmitting antenna is placed parallel to the imaging plane of the second elliptical reflector 6. The terahertz transmitting antenna emits divergent terahertz waves, which are reflected as parallel terahertz waves at the first off-axis parabolic mirror 2. The parallel terahertz waves are reflected by the first elliptical reflector 3 at a first distance from the center of the parabolic mirror along the positive Y-axis. The reflected terahertz waves are reflected again and focused by the second off-axis parabolic mirror 4 at a second distance from the center of the second elliptical reflector 6 along the negative X-axis. The reflected terahertz waves are then focused along a first direction between the negative Y-axis and the positive Z-axis, forming 45° angles with the Z and Y axes, respectively. The terahertz wave propagates at a distance of 3 from the center of the second off-axis parabolic mirror 4 and is reflected. The terahertz wave then diverges along the second direction between the positive Z and Y axes, forming a 45° angle with the Z and Y axes respectively. It is reflected as parallel light by the third off-axis parabolic mirror 5 at a distance of 4 from the center of the second off-axis parabolic mirror 4. The reflected terahertz wave propagates along the negative X-axis to the elliptical mirror 6 at a distance of d5 from the second off-axis parabolic mirror 5. The reflected terahertz wave propagates along the negative Y-axis to the fourth off-axis parabolic mirror 7 at a distance of 6 from the second elliptical mirror 6. After reflection, the terahertz wave is focused onto the terahertz receiving photoconductive antenna 107.

[0062] In a preferred embodiment, such as Figure 3 As shown, the transmission measurement module includes,

[0063] The fifth off-axis parabolic mirror 12 reflects the incident terahertz wave emitted by the terahertz transmitting photoconductive antenna 106 into a parallel terahertz wave along the positive Y-axis direction.

[0064] The third elliptical mirror 13 is located in the positive Y-axis direction of the fifth off-axis parabolic mirror 12. There is a seventh distance between the centers of the third elliptical mirror 13 and the fifth off-axis parabolic mirror 12. It is used to reflect terahertz waves from the fifth elliptical mirror in the negative X-axis direction.

[0065] The sixth off-axis parabolic mirror 14 is located in the negative X-axis direction of the third elliptical mirror 13. There is an eighth distance between the center of the sixth off-axis parabolic mirror 14 and the center of the third elliptical mirror 13. It is used to reflect the terahertz wave from the third elliptical mirror 13 to the sample to be tested.

[0066] The sample to be tested 18 is located on the negative Y-axis direction of the sixth off-axis parabolic mirror 14, and there is a ninth distance between the sample to be tested and the center of the sixth off-axis parabolic mirror 14.

[0067] The seventh off-axis parabolic mirror 15 is located in the negative Y-axis direction of the sample to be tested. There is a tenth distance between the seventh off-axis parabolic mirror 15 and the sample to be tested. The seventh off-axis parabolic mirror 15 is used to reflect the diverging terahertz wave from the sample to be tested into a parallel terahertz wave that propagates along the negative X-axis direction.

[0068] The fourth elliptical reflector 16 is located in the negative X-axis direction of the seventh off-axis parabolic mirror 15. There is an eleventh distance between the center of the fourth elliptical reflector 16 and the center of the seventh off-axis parabolic mirror 15. It is used to reflect terahertz waves from the seventh off-axis parabolic mirror 15 in the negative Z-axis direction.

[0069] The eighth off-axis parabolic mirror 17 is located on the positive Z-axis direction of the fourth elliptical mirror 16. There is a twelfth distance between the center of the eighth off-axis parabolic mirror 17 and the center of the fourth elliptical mirror 16. The eighth off-axis parabolic mirror 17 is used to reflect and focus the terahertz wave from the fourth elliptical mirror 16 onto the terahertz receiving photoconductive antenna 107.

[0070] Specifically, the terahertz transmitting antenna emits divergent terahertz waves, which are reflected as parallel terahertz waves at the fifth off-axis parabolic mirror 12. These waves are then reflected again by the third elliptical mirror 13, located at a distance of seven from the center of the fifth parabolic mirror along the positive Y-axis. The reflected terahertz waves are then reflected again by the sixth off-axis parabolic mirror 14, located at a distance of eight from the center of the third elliptical mirror 13 along the negative X-axis. The reflected terahertz waves are then focused along the negative Y-axis onto the sample 18, located at a distance of nine from the sixth off-axis parabolic mirror 14. The waves then diverge through the sample and reach the seventh off-axis parabolic mirror 15, located at a distance of ten from the sample 18, where they are reflected as parallel terahertz waves. These parallel terahertz waves are then reflected by the fourth elliptical mirror 16, located at a distance of ten from the seventh off-axis parabolic mirror 15 along the negative X-axis. Finally, the reflected terahertz waves are reflected by the eighth off-axis parabolic mirror 17, located at a distance of eleven from the fourth elliptical mirror 16 along the positive Z-axis, and focused onto the terahertz receiving photoconductive antenna 107.

[0071] In a preferred embodiment, such as Figure 4 As shown, the focused light attenuation total internal reflection measurement module includes,

[0072] The ninth off-axis parabolic mirror 22 reflects the incident terahertz wave emitted by the terahertz transmitting photoconductive antenna 106 into a parallel terahertz wave along the positive Z-axis direction.

[0073] The tenth off-axis parabolic mirror 23 is located on the positive Z-axis direction of the ninth off-axis parabolic mirror 22. There is a thirteenth distance between the centers of the tenth off-axis parabolic mirror 23 and the ninth off-axis parabolic mirror 22. It is used to reflect terahertz waves from the ninth off-axis parabolic mirror 22 in the negative X-axis direction.

[0074] A silicon prism 24 is positioned on the negative X-axis direction of the tenth off-axis parabolic mirror 23, and the sample to be tested is placed on the silicon prism.

[0075] The eleventh off-axis parabolic mirror 25 is located in the negative X-axis direction of the silicon prism. There is a fourteenth distance between the eleventh off-axis parabolic mirror 25 and the tenth off-axis parabolic mirror 23. The eleventh off-axis parabolic mirror 25 is used to reflect the terahertz wave diverging from the silicon prism into a parallel terahertz wave propagating in the negative Y-axis direction.

[0076] The twelfth off-axis parabolic mirror 26 is located on the negative Y-axis direction of the eleventh off-axis parabolic mirror 25. There is a fifteenth distance between the centers of the twelfth off-axis parabolic mirror 26 and the eleventh off-axis parabolic mirror 25. The twelfth off-axis parabolic mirror 26 is used to reflect and focus the terahertz wave from the eleventh off-axis parabolic mirror 25 onto the terahertz receiving photoconductive antenna 107.

[0077] Specifically, the terahertz transmitting antenna emits a terahertz wave, which is reflected as a parallel terahertz wave at the eighth off-axis parabolic mirror 17. The reflected terahertz wave is then reflected by the tenth off-axis parabolic mirror 23, located thirteenth distance from the center of the ninth parabolic mirror along the positive Z-axis. The reflected terahertz wave is incident on the silicon prism 24 along the negative X-axis, undergoes attenuation and total reflection, and is then emitted to the eleventh off-axis parabolic mirror 25, located fourteenth distance from the tenth off-axis parabolic mirror 23, where it is reflected as a parallel terahertz wave. The parallel terahertz wave is then reflected by the twelfth off-axis parabolic mirror 26, located fifteenth distance from the eleventh off-axis parabolic mirror 25, along the negative Y-axis and focused onto the terahertz receiving photoconductive antenna 107.

[0078] In a preferred embodiment, the distance between the photoconductive antenna and the off-axis parabolic mirror corresponding to the three test modules 108 can be obtained from the specific off-axis parabolic mirror focal length index.

[0079] In a preferred embodiment, the test module 108 has a preset Z-axis length, a third distance is determined based on the focal length of the second off-axis parabolic mirror 4, and a fourth distance is determined based on the focal length of the third off-axis parabolic mirror 5. The Z-axis length of the test module 108 is the third distance multiplied by the cosine of the angle between the terahertz wave reflected by the second off-axis parabolic mirror 4 and the Z-axis, plus the fourth distance to form the cosine of the angle between the terahertz wave received by the third off-axis parabolic mirror 5 and the Z-axis.

[0080] In this embodiment, the reflected terahertz wave travels along the negative Y-axis and the positive Z-axis, forming 45° with the Z and Y axes respectively. The terahertz wave is focused on the sample 9 to be tested at a distance of three from the center of the second off-axis parabolic mirror 4 and reflected. The terahertz wave then diverges and propagates along the positive Z and Y axes, forming 45° with the Z and Y axes respectively. Therefore, based on the specific focal length of the off-axis parabolic mirror, the length of the probe's Z-axis can be obtained as follows: In a preferred embodiment, the test module 108 has a preset Y-axis length, determines a ninth distance based on the focal length of the sixth off-axis parabolic mirror 14 and a tenth distance based on the focal length of the seventh off-axis parabolic mirror 15, and the Y-axis length of the test module 108 is the ninth distance plus the tenth distance.

[0081] In a preferred embodiment, the sixth and fifteenth distances are determined based on the Y-axis length of the test module 108. The fifteenth distance is the ninth distance plus the tenth distance minus the seventh distance. The seventh distance is related to the structural design, and its length can vary according to the size of the structural components. For example, if the size of the off-axis parabolic mirror and the elliptical reflector are both 1 inch, in order to increase the stability of the optical path and shorten the optical path, the seventh distance in this embodiment is 30mm.

[0082] In a preferred embodiment, the test module 108 has a preset X-axis length, and a fourteenth distance is determined based on the size of the silicon prism 24, which serves as the X-axis length of the test module 108.

[0083] In a preferred embodiment, the lengths of the second distance plus the fifth distance and the eighth distance plus the eleventh distance are determined based on the fourteenth distance.

[0084] Specifically, the present invention uses a transmission test probe to determine the overall Y-axis length of the probe, a reflection test probe to determine the overall X-axis length, and an ATR probe to determine the overall Z-axis length of the probe, thereby determining the final position of the antenna.

[0085] In a preferred embodiment, the terahertz receiving photoconductive antenna 107 is connected to the femtosecond laser 101 via a second optical fiber 103 and a third optical fiber 104, receives the probe light and the output terahertz wave carrying the information of the sample to be tested, and converts the optical signal into an electrical signal to output the information of the sample to be tested; an optical delay line for changing the optical path of the probe light is provided between the second optical fiber 103 and the third optical fiber 104.

[0086] The above description is merely a preferred embodiment of the present invention and does not limit the implementation and protection scope of the present invention. Those skilled in the art should realize that any equivalent substitutions and obvious changes made based on the description and illustrations of the present invention should be included within the protection scope of the present invention.

Claims

1. A terahertz time-domain spectroscopy system for multiplexing probes in a test module, characterized in that, include, A femtosecond laser, wherein the femtosecond laser outputs a pump beam and a probe beam; A terahertz photoconductive antenna is connected to the femtosecond laser via a first optical fiber to receive the pump light and generate an incident terahertz wave excited by the pump light. A replaceable test module, wherein the test module receives the incident terahertz wave and generates an output terahertz wave carrying information about the sample to be tested, and the test module is configured as a reflection measurement module, a transmission measurement module, or a focused light attenuation total internal reflection measurement module based on the test requirements. A terahertz receiving photoconductive antenna is set up in correspondence with the test module to receive the probe light and the output terahertz wave carrying the information of the sample to be tested, and converts the optical signal into an electrical signal to output the information of the sample to be tested; The reflection measurement module includes, The first off-axis parabolic mirror reflects the incident terahertz wave emitted by the terahertz transmitting photoconductive antenna into a parallel terahertz wave along the positive Y-axis direction. A first elliptical reflector is disposed on the positive Y-axis direction of the first off-axis parabolic mirror, and there is a first distance between the center of the first elliptical reflector and the center of the first off-axis parabolic mirror, for reflecting terahertz waves from the first elliptical reflector in the negative X-axis direction. The second off-axis parabolic mirror is disposed in the negative X-axis direction of the first elliptical mirror, and there is a second distance between the center of the second off-axis parabolic mirror and the center of the first elliptical mirror, for reflecting the terahertz wave from the first elliptical mirror to the sample to be tested. The sample to be tested is located in a first direction between the negative Y-axis and the positive Z-axis of the second off-axis parabolic mirror, and there is a third distance between the sample to be tested and the center of the second off-axis parabolic mirror. A third off-axis parabolic mirror is disposed in a second direction between the positive Z-axis direction and the positive Y-axis direction of the sample to be tested. A fourth distance exists between the third off-axis parabolic mirror and the sample to be tested. The third off-axis parabolic mirror is used to reflect the diverging terahertz wave from the sample to be tested into a parallel terahertz wave propagating along the negative X-axis direction. The second elliptical reflector is located in the negative X-axis direction of the third off-axis parabolic mirror. There is a fifth distance between the centers of the second elliptical reflector and the third off-axis parabolic mirror. It is used to reflect terahertz waves from the third off-axis parabolic mirror in the negative Y-axis direction. A fourth off-axis parabolic mirror is disposed on the negative Y-axis direction of the second elliptical mirror. There is a sixth distance between the center of the fourth off-axis parabolic mirror and the center of the second elliptical mirror. The fourth off-axis parabolic mirror is used to reflect and focus the terahertz wave from the second elliptical mirror onto the terahertz receiving photoconductive antenna. The transmission measurement module includes, The fifth off-axis parabolic mirror reflects the incident terahertz wave emitted by the terahertz transmitting photoconductive antenna into a parallel terahertz wave along the positive Y-axis direction. The third elliptical mirror is located in the positive Y-axis direction of the fifth off-axis parabolic mirror. There is a seventh distance between the center of the third elliptical mirror and the center of the fifth off-axis parabolic mirror. It is used to reflect terahertz waves from the fifth off-axis parabolic mirror in the negative X-axis direction. The sixth off-axis parabolic mirror is located on the negative X-axis direction of the third elliptical mirror. There is an eighth distance between the center of the sixth off-axis parabolic mirror and the center of the third elliptical mirror. It is used to reflect the terahertz wave from the third elliptical mirror to the sample to be tested. The sample to be tested is located on the negative Y-axis direction of the sixth off-axis parabolic mirror, and there is a ninth distance between the sample to be tested and the center of the sixth off-axis parabolic mirror; A seventh off-axis parabolic mirror is disposed in the negative Y-axis direction of the sample to be tested. There is a tenth distance between the seventh off-axis parabolic mirror and the sample to be tested. The seventh off-axis parabolic mirror is used to reflect the divergent terahertz wave from the sample to be tested into a parallel terahertz wave propagating in the negative X-axis direction. The fourth elliptical reflector is located in the negative X-axis direction of the seventh off-axis parabolic mirror. There is an eleventh distance between the center of the fourth elliptical reflector and the center of the seventh off-axis parabolic mirror. It is used to reflect terahertz waves from the seventh off-axis parabolic mirror in the negative Z-axis direction. The eighth off-axis parabolic mirror is located on the positive Z-axis direction of the fourth elliptical mirror. There is a twelfth distance between the center of the eighth off-axis parabolic mirror and the center of the fourth elliptical mirror. The eighth off-axis parabolic mirror is used to reflect and focus the terahertz wave from the fourth elliptical mirror onto the terahertz receiving photoconductive antenna. The focused light attenuation total internal reflection measurement module includes, The ninth off-axis parabolic mirror reflects the incident terahertz wave emitted by the terahertz transmitting photoconductive antenna into a parallel terahertz wave along the positive Z-axis direction. The tenth off-axis parabolic mirror is located in the positive Z-axis direction of the ninth off-axis parabolic mirror. There is a thirteenth distance between the centers of the tenth off-axis parabolic mirror and the ninth off-axis parabolic mirror. It is used to reflect terahertz waves from the ninth off-axis parabolic mirror in the negative X-axis direction. A silicon prism is positioned on the negative X-axis direction of the tenth off-axis parabolic mirror, and the sample to be tested is placed on the silicon prism. The eleventh off-axis parabolic mirror is located on the negative X-axis direction of the silicon prism. There is a fourteenth distance between the centers of the eleventh off-axis parabolic mirror and the tenth off-axis parabolic mirror. The eleventh off-axis parabolic mirror is used to reflect the terahertz waves diverging from the silicon prism into parallel terahertz waves propagating along the negative Y-axis direction. The twelfth off-axis parabolic mirror is located on the negative Y-axis direction of the eleventh off-axis parabolic mirror. There is a fifteenth distance between the centers of the twelfth off-axis parabolic mirror and the eleventh off-axis parabolic mirror. The twelfth off-axis parabolic mirror is used to reflect and focus the terahertz wave from the eleventh off-axis parabolic mirror onto the terahertz receiving photoconductive antenna.

2. The terahertz time-domain spectroscopy system with multiplexed probes in the test module according to claim 1, characterized in that, The test module has a preset Z-axis length, determines the third distance based on the focal length of the second off-axis parabolic mirror, and determines the fourth distance based on the focal length of the third off-axis parabolic mirror. The Z-axis length of the test module is the third distance multiplied by the cosine of the angle between the terahertz wave reflected by the second off-axis parabolic mirror and the Z-axis, plus the fourth distance, to obtain the cosine of the angle between the terahertz wave received by the third off-axis parabolic mirror and the Z-axis.

3. The terahertz time-domain spectroscopy system with probe multiplexing in the test module according to claim 2, characterized in that, The test module has a preset Y-axis length, determines the ninth distance based on the focal length of the sixth off-axis parabolic mirror, and determines the tenth distance based on the focal length of the seventh off-axis parabolic mirror. The Y-axis length of the test module is the ninth distance plus the tenth distance.

4. The terahertz time-domain spectroscopy system with probe multiplexing in the test module according to claim 3, characterized in that, The sixth distance and the fifteenth distance are determined based on the Y-axis length of the test module, wherein the fifteenth distance is the ninth distance plus the tenth distance minus the seventh distance.

5. The terahertz time-domain spectroscopy system with probe multiplexing in the test module according to claim 4, characterized in that, The test module has a preset X-axis length, and the fourteenth distance is determined based on the size of the silicon prism. The fourteenth distance is used as the X-axis length of the test module.

6. The terahertz time-domain spectroscopy system with probe multiplexing in the test module according to claim 5, characterized in that, The X-axis length of the test module is used as the length of the second distance plus the fifth distance and the length of the eighth distance plus the eleventh distance.

7. The terahertz time-domain spectroscopy system with probe multiplexing in the test module according to claim 1, characterized in that, The terahertz receiving photoconductive antenna is connected to the femtosecond laser via a second optical fiber and a third optical fiber. It receives the probe light and the output terahertz wave carrying information about the sample to be tested, and converts the optical signal into an electrical signal to output the information about the sample to be tested. An optical delay line for changing the optical path of the probe light is provided between the second optical fiber and the third optical fiber.

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