Terahertz source radiation intensity far field measurement device, method and debugging optical path method

Abstract

The application provides a terahertz source radiation intensity far field measurement device and method and a method for debugging an optical path. The device belongs to the field of optical measurement and metrology and comprises a terahertz emission system, a terahertz attenuation system, a terahertz detection system, an extension adapter plate and a computer. The device can realize far field distribution testing of a terahertz source with an output power greater than 1 mW in a (0.1-10) THz wave band range. The measurement method comprises the following steps: recording the terahertz radiation power measured by a terahertz power meter as Pm, adjusting the diameter of an aperture as D, recording the transmittance of a terahertz attenuator as τ1, recording the transmittance of a terahertz narrow band filter as τ2, recording the reflectivity of each wedge-shaped reflector as R, recording the number of wedge-shaped reflectors as n, recording the distance between a measured terahertz radiator and a variable aperture as L, and calculating the radiation intensity value of the measured terahertz radiator by using a formula. The device can ensure the value accuracy of the terahertz source radiation result measured in the far field.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical measurement and metrology, in particular, to a terahertz source radiation intensity far field measurement device, method and method for debugging an optical path. BACKGROUND

[0002] The terahertz wave band is located between the infrared and the microwave, and the terahertz technology is an international cross-cutting frontier technology. With the rapid development of the terahertz technology, various terahertz sources such as terahertz free electron lasers, terahertz quantum cascade lasers, terahertz gas lasers, Schottky terahertz sources, backward wave tubes, traveling wave tubes and photoconductive antennas have been developed at home and abroad. The terahertz source is an important development direction of the terahertz technology, and the performance of the terahertz source is directly related to the overall index of the terahertz imaging and communication systems. The radiation intensity is an important index for characterizing the spatial distribution of the terahertz source output radiation, and is related to the imaging distance, imaging resolution and other parameters of the terahertz imaging system, and the communication distance and other parameters of the terahertz communication system.

[0003] The utility model discloses a kind of based on compressed sensing's terahertz radiation intensity distribution detection device, and design includes expansion lens group, mask plate, one-dimensional electric displacement platform, terahertz power meter or energy meter, focusing lens and computer, can be based on specific mask plate, only using one-dimensional moving platform and terahertz radiation power meter, just can realize the fast high-sensitivity detection of terahertz radiation intensity distribution, using different resolution mask plate and different lens combination can realize the imaging of different resolution to radiation intensity distribution. This method can be applied to the radiation intensity distribution measurement of different wave band. With infrared thermal radiation detector Bolometer, the power detection of pW order can be realized. But the defect is: Bolometer detector must be liquid helium refrigeration in use, and the upper limit of power measurement is only several microwatts, and the measurement of the far field radiation intensity of the terahertz source with output power greater than 1mW cannot be realized. In addition, the existing terahertz source radiation intensity measurement system is only suitable for near field terahertz radiation measurement, and the measurement result is inaccurate in far field measurement. SUMMARY

[0004] The purpose of the present application is to provide a terahertz source radiation intensity far field measurement device, method and method for debugging an optical path, which can ensure the accuracy of the far field measurement of the terahertz source radiation result.

[0005] The present application is realized as follows:

[0006] In a first aspect, the present application provides a terahertz source radiation intensity far field measurement device, comprising: a terahertz emission system, a terahertz attenuation system, a terahertz detection system, an extension adapter plate and a computer.

[0007] The terahertz emission system comprises a measured terahertz radiator;

[0008] The terahertz attenuation system comprises a variable diaphragm, an optical reflection group and a terahertz attenuator which are installed on the extension adapter plate; the center of the variable diaphragm is located on the same optical axis as the geometric center of the terahertz wave radiator outlet, and is used for controlling the radiation amount of the measured terahertz wave radiator; the optical reflection group comprises an off-axis parabolic mirror and n wedge-shaped mirrors, the focal point of the off-axis parabolic mirror coincides with the outlet of the measured terahertz radiator, and is used for converting the terahertz radiation emitted by the measured terahertz radiator into parallel light which is incident on the wedge-shaped mirrors; the n wedge-shaped mirrors attenuate the terahertz radiation and then make it incident on the terahertz attenuator; and the terahertz attenuator is used for realizing different attenuation multiples.

[0009] The terahertz detection system comprises a terahertz narrow-band filter, a rotating wheel, a chopper and a terahertz power meter which are installed on the extension adapter plate; the terahertz narrow-band filter is installed on the rotating wheel, and is used for controlling the rotating wheel to rotate the corresponding terahertz narrow-band filter into the light path according to the output frequency of the measured terahertz radiator when measuring the radiation intensity, so as to segmentally filter out the infrared radiation of the measured terahertz wave radiator; the chopper is used for converting continuous terahertz radiation into pulsed terahertz radiation; and the terahertz power meter is used for receiving the pulsed terahertz radiation which is incident on the detection surface thereof, and outputting a signal to a computer to calculate the radiation intensity value of the measured terahertz radiator.

[0010] Based on the first aspect, the terahertz emission system further comprises a rotating table; the outlet of the measured terahertz radiator is located at the center of the rotating table, the terahertz wave radiator outlet position does not change with the rotation of the rotating table, and the focal point of the off-axis parabolic mirror is located at the center of the rotating table.

[0011] Based on the first aspect, the extension adapter plate is connected with the rotating table and can rotate synchronously with the rotating table.

[0012] Based on the first aspect, the aperture of the variable diaphragm can be adjusted to be larger than the outlet aperture of the measured terahertz wave radiator.

[0013] Based on the first aspect, the surface of the wedge-shaped mirror is coated with a reflective film with a certain reflectivity, which is used for attenuating the terahertz radiation and then making it incident on the terahertz attenuator.

[0014] Based on the first aspect, the terahertz attenuator comprises a plurality of groups of metal thin film attenuators with different transmittances, and the plurality of groups of metal thin film attenuators with different transmittances can be used singly or in combination to realize different attenuation multiples.

[0015] The second aspect provides a method for measuring the far-field radiation intensity of a terahertz source, which uses the measuring device described above, and the method comprises the following steps:

[0016] The terahertz radiation power measured by the terahertz power meter is denoted as Pm, the diameter of the diaphragm is adjusted according to the radiation exit of the measured terahertz radiator during measurement, the transmittance of the terahertz attenuator is denoted as τ1, the transmittance of the terahertz narrow-band filter is denoted as τ2, the reflectivity of each wedge-shaped mirror is R, the number of wedge-shaped mirrors is n, the distance between the measured terahertz radiator and the variable diaphragm is denoted as L, and the radiation intensity value I of the measured terahertz radiator 1-1 is calculated by using formula (1):

[0017]

[0018] Based on the second aspect, the number of wedge-shaped mirrors is determined by the following steps:

[0019] The output power of the measured terahertz radiator is P O , the upper limit of the detection power of the terahertz power meter is P max , the attenuation multiple of the terahertz attenuator is α, the reflectivity of each wedge-shaped mirror is R, the required number of wedge-shaped mirrors is n, P o · α · R n ≤ P max , and n is determined by the following formula: When is not an integer, n is rounded up.

[0020] The third aspect provides a method for debugging an optical path, applied to the measurement device, and the method comprises the following steps:

[0021] S1: Place the first target at the center of the turntable, and make the visible laser beam emitted by the collimating laser incident on the first target, adjust the position of the collimating laser to make the center of the beam spot coincide with the center of the cross of the first target, and the center of the beam spot of the collimating laser and the center of the cross of the first target jointly constitute the main light path of the debugging optical path;

[0022] S2: Place the second target perpendicular to the main light path, so that the center of the cross of the second target coincides with the center of the beam spot of the laser;

[0023] S3: Place the semi-transparent half-mirror on the main light path, and adjust the position of the semi-transparent half-mirror so that the center of the transmitted laser beam spot coincides with the center of the cross of the second target;

[0024] S4: Place the third target in the reflected light path, so that the center of the cross of the third target coincides with the center of the beam spot of the reflected light path;

[0025] S5: Move the semi-transparent half-mirror 7 out of the main light path, and place the off-axis parabolic mirror into the main light path, and adjust the position of the parabolic mirror so that the center of the outgoing beam coincides with the center of the cross of the third target;

[0026] S6: remove the collimated laser, the first target, the second target and the third target, and the optical path debugging is completed.

[0027] Compared with the prior art, the present application has at least the following advantages or beneficial effects:

[0028] The present application provides a terahertz source radiation intensity far field measurement device, including a terahertz emission system, a terahertz attenuation system, a terahertz detection system, an extension adapter plate and a computer, which can realize the far field distribution test of the terahertz source radiation intensity in the (0.1-10) THz wave band range, and the output power is greater than 1 mW. The terahertz attenuation system includes a variable diaphragm, an optical reflection group and a terahertz attenuator, the optical reflection group includes an off-axis parabolic mirror and a wedge-shaped mirror, the wedge-shaped mirror group replaces the plane mirror group, and solves the problem of inaccurate measurement of terahertz radiation intensity caused by multiple reflections of the front and back surfaces of the plane mirror; the reflectivity of the wedge-shaped mirror and the attenuation multiple of the terahertz attenuator are set, and the overall attenuation coefficient of the terahertz attenuation system is obtained, so that the value accuracy of the measurement result is ensured. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0030] Figure 1 It is a structural schematic diagram of an embodiment of the terahertz source radiation intensity far field measurement device of the present application.

[0031] Figure 2 It is a schematic diagram of debugging the optical path in an embodiment of the method for debugging the optical path of the present application.

[0032] Figure 3 It is a flow chart in an embodiment of the method for debugging the optical path of the present application.

[0033] Icon:

[0034] 1, terahertz emission system; 11, measured terahertz radiator; 12, rotary table; 2, terahertz attenuation system; 21, variable diaphragm; 22, optical reflection group; 221, off-axis parabolic mirror; 222, wedge-shaped mirror; 23, terahertz attenuator; 3, terahertz detection system; 31, terahertz narrow-band filter; 32, rotating wheel; 33, chopper; 34, terahertz power meter; 4, extension adapter plate; 5, computer; 6, collimated laser; 7, half-transmission half-reflection mirror; 81, first target; 82, second target; 83, third target. DETAILED DESCRIPTION

[0035] To make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will be combined with the accompanying drawings to make a clear and complete description of the technical solutions in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. The components of the embodiments of the present application described and shown in the accompanying drawings can be arranged and designed in various different configurations.

[0036] The following will be a detailed description of some embodiments of the present application in combination with the accompanying drawings. In the case of no conflict, each of the following embodiments and each feature in the embodiments can be combined with each other.

[0037] Embodiments

[0038] Through long-term research and practice, the applicant finds that a Bolometer detector used in a kind of terahertz radiation intensity measurement method in the prior art must be liquid helium refrigerated in use, and the upper limit of power measurement is only several microwatts, so that the measurement of the far-field radiation intensity of the terahertz source with output power greater than 1mW cannot be realized. In addition, the existing terahertz source radiation intensity measurement method is only suitable for near-field terahertz radiation measurement, and in far-field measurement, the measurement result is inaccurate.

[0039] In view of this, the embodiments of the present application provide a terahertz source radiation intensity far-field measurement device for measuring the spatial distribution of the terahertz source radiation intensity far field, which can improve the accuracy of far-field measurement of the terahertz source radiation.

[0040] Please refer to Figure 1 , the device comprises a terahertz emission system 1, a terahertz attenuation system 2, a terahertz detection system 3, an extension adapter plate 4 and a computer 5;

[0041] The terahertz emission system 1 comprises a measured terahertz radiator 11; specifically, the measured terahertz radiator 11 is used to generate electromagnetic radiation in the terahertz wave band.

[0042] The terahertz attenuation system 2 comprises a variable diaphragm 21, an optical reflection group 22 and a terahertz attenuator 23 installed on the extension adapter plate 4; the center of the variable diaphragm 21 is located on the same optical axis as the geometric center of the terahertz wave radiator outlet, and is used to control the radiation amount of the measured terahertz wave radiator; the optical reflection group 22 comprises an off-axis parabolic mirror 221 and n wedge-shaped mirrors 222, the focal point of the off-axis parabolic mirror 221 coincides with the exit port of the measured terahertz radiator 11, and is used to convert the terahertz radiation emitted by the measured terahertz radiator 11 into parallel light incident to the wedge-shaped mirrors 222, the n wedge-shaped mirrors 222 attenuate the terahertz radiation and then incident to the terahertz attenuator 23; the terahertz attenuator 23 is used to realize different attenuation multiples;

[0043] Specifically, the variable aperture 21 can precisely control the amount of terahertz wave radiation passing through it by adjusting the size of the opening to reduce or increase the amount of radiation. The optical reflection group 22 is composed of an off-axis parabolic mirror 221 and several wedge-shaped mirrors 222. Preferably, the off-axis parabolic mirror 221 is made of super-hard aluminum, the surface is coated with a gold reflective film, it is 90° off-axis, the reflectivity is greater than 99.5%, the clear aperture is 50.8mm, and the focal length is 101.6mm. After passing through the variable aperture 21, the terahertz wave radiation is converted into parallel light by the off-axis parabolic mirror 221. The parallel light helps to ensure that the terahertz wave maintains stable intensity and direction during subsequent propagation. When the parallel light is incident on the wedge-shaped mirror 222, part of the terahertz wave is reflected back, and another part continues to propagate. Further, the wedge-shaped mirror 222 is coated with a reflective film with a certain reflectivity on its surface. This thin film can reflect a certain proportion of light. Such processing enables the wedge-shaped mirror 222 to more effectively perform its functions in the optical system, such as changing the direction of light and adjusting the optical path. By adjusting the number and angle of the wedge-shaped mirrors 222, the degree of attenuation of the terahertz wave can be further controlled. Finally, the terahertz attenuator 23 makes the final intensity adjustment as needed. Further, the terahertz attenuator 23 includes several groups of metal film attenuator sheets with different transmittances, which can be used singly or in combination to achieve different attenuation multiples. When only slight attenuation is needed, a single metal film attenuator sheet with high transmittance can be selected. In this way, most of the terahertz wave can pass through, and only a small part is attenuated. When greater attenuation is needed, multiple metal film attenuator sheets can be combined for use. Each sheet further attenuates the terahertz wave, so the attenuation effect after combination will be more significant. By selecting different combinations of attenuator sheets, different attenuation multiples can be achieved. Through such settings, the degree of attenuation of the terahertz wave can be flexibly controlled to meet different testing needs. The present embodiment uses a wedge-shaped mirror group instead of the existing plane mirror group, solving the problem of inaccurate measurement of terahertz radiation intensity caused by multiple reflections on the front and back surfaces of the plane mirror; by setting the reflectivity of the wedge-shaped mirror 222 and the attenuation multiple of the terahertz attenuator 23, the overall attenuation coefficient of the terahertz attenuation system 2 is obtained, thereby ensuring the quantitative accuracy of the measurement results.

[0044] The terahertz detection system 3 includes a terahertz narrow-band filter 31, a rotating wheel 32, a chopper 33 and a terahertz power meter 34 mounted on the extension adapter plate 4. The terahertz narrow-band filter 31 is mounted on the rotating wheel 32, and is used to control the rotating wheel 32 to rotate the corresponding terahertz narrow-band filter 31 into the light path according to the output frequency of the measured terahertz radiator 11 when measuring the radiation intensity, so as to segmentally filter out the infrared radiation of the to-be-measured terahertz wave radiator. The chopper 33 is used to convert continuous terahertz radiation into pulsed terahertz radiation. The terahertz power meter 34 is used to receive the pulsed terahertz radiation incident to the detection surface thereof, and output a signal to the computer 5 to calculate the radiation intensity value of the measured terahertz radiator 11.

[0045] Specifically, the terahertz narrow-band filter 31 is a filter that can selectively transmit terahertz waves of a specific frequency range. It is installed on the rotating wheel 32 so that different filters can be selected as needed. The rotating wheel 32 is a device for rotating the terahertz narrow-band filter 31. By rotating, different frequency range filters can be rotated into the light path to segmentally filter out terahertz waves. The chopper 33 is a device for converting continuous terahertz radiation into pulsed terahertz radiation. The chopper 33 contains a fast-switching blade that can quickly open and close when terahertz waves pass through, thereby converting continuous radiation into a series of pulses. The terahertz power meter 34 is a device for measuring the intensity of terahertz waves. It has a detection surface that can receive incident pulsed terahertz radiation and convert it into an electrical signal. This electrical signal can then be processed by the computer 5 to calculate the radiation intensity value of the measured terahertz radiator 11. Preferably, the terahertz power meter 343-4 uses the TK100 detector produced by the British Thomas Keating Company, which can realize automatic calibration of terahertz absolute power, frequency 30GHz-3THz, window diameter 40mm, continuous power measurement upper limit 500mW, pulse energy 100mJ at 5Hz repetition frequency, NEP value 5μW / Hz1 / 2. Through the coordinated work of the terahertz narrow-band filter 31, the rotating wheel 32, the chopper 33 and the terahertz power meter 34 mounted on the extension adapter plate 4, the device can accurately measure the radiation intensity value of the measured terahertz radiator 11. It realizes the far-field distribution test of the radiation intensity of a terahertz source with an output power greater than 1mW in the (0.1-10)THz waveband range.

[0046] Based on the first aspect, the terahertz emission system 1 further includes a turntable 12; the exit port of the measured terahertz radiator 11 is located at the center of the turntable 12, the terahertz wave radiator exit position does not change with the rotation of the turntable 12, and the focal point of the off-axis parabolic mirror 221 is located at the center of the turntable 12.

[0047] Specifically, the rotating table 12 is a high-precision rotating table 12, which has high accuracy and stability during rotation. The rotating table 12 is provided with a bearing part for bearing the measured terahertz radiator 11. The exit port of the measured terahertz radiator 11 (i.e. the element generating terahertz waves) is located at the center position of the rotating table 12. Regardless of the rotation of the rotating table 12, the exit port of the measured terahertz radiator 11 remains at a fixed position relative to the center of the rotating table 12, and the position of the terahertz wave emission does not change, ensuring the stability and consistency of the terahertz wave during emission. The off-axis parabolic mirror is placed at the center position of the rotating table 12, and its focal point coincides with the exit port of the measured terahertz radiator 11. The terahertz wave emitted from the measured terahertz radiator 11 is directly focused on the focal point of the off-axis parabolic mirror 221, and then reflected or collimated into the required beam shape. The purpose of such arrangement is to ensure the stability and consistency of the beam during the emission of the terahertz wave.

[0048] Further, the extension adapter plate 4 is connected with the rotating table 12 and can rotate synchronously with the rotating table 12.

[0049] Specifically, the extension adapter plate 4 is connected with the rotating table 12 through mechanical connection and has a synchronous motion relationship. When the rotating table 12 rotates, the extension adapter plate 4 also rotates synchronously. Such synchronous motion ensures that the elements on the extension adapter plate 4 can rotate and position in a predetermined manner.

[0050] The embodiment of the present application also provides a terahertz source radiation intensity far-field measurement method, which applies the terahertz source radiation intensity far-field measurement device and is used for measuring the far-field spatial distribution of the terahertz source radiation intensity. The measurement method comprises the following steps:

[0051] The terahertz radiation power measured by the terahertz power meter 34 is recorded as Pm. The diameter of the diaphragm is adjusted to D according to the radiation exit port of the measured terahertz radiator 11 during measurement. The transmittance of the terahertz attenuator 23 is recorded as τ1. The transmittance of the terahertz narrow-band filter 31 is recorded as τ2. The reflectivity of each wedge-shaped mirror 222 is R. The number of wedge-shaped mirrors 222 is n. The distance between the measured terahertz radiator 11 and the variable diaphragm 21 is recorded as L. The radiation intensity value I of the measured terahertz radiator 11 is calculated by using formula (1):

[0052]

[0053] Specifically, the radiation intensity value I of the measured terahertz radiator 11 is obtained by formula (1).

[0054] Further, the number determination method (the determination method of n) of the wedge-shaped mirrors 222 in the n wedge-shaped mirrors 222 comprises the following steps:

[0055] The output power of the measured terahertz radiator 11 is P O The upper limit of the detection power of the terahertz power meter 34 is P max The attenuation multiple of the terahertz attenuator 23 is a, the reflectivity of each wedge-shaped mirror 222 is R, the number of the required wedge-shaped mirrors 222 is n, and P o · a · R n ≤ P max The value of n satisfies When is not an integer, the value of n is rounded up.

[0056] Specifically, the number of the wedge-shaped mirrors 222 is determined through the step.

[0057] Please refer to Figures 2-3 The embodiment of the present application also provides a method for debugging an optical path, which is applied to the above measuring device and includes the following steps.

[0058] S1: The No. 1 target 81 is placed at the center of the turntable 12, the visible laser beam emitted by the collimating laser 6 is incident on the No. 1 target 81, and the position of the collimating laser 6 is adjusted so that the center of the beam spot of the collimating laser 6 is coincident with the cross center of the No. 1 target 81, and the center of the beam spot of the collimating laser 6 and the cross center of the No. 1 target 81 jointly constitute a main light path of the debugging optical path.

[0059] Specifically, the middle part of the No. 1 target 81, the No. 2 target 82 and the No. 3 target 83 has a cross mark, which is used as a reference point for beam alignment. The laser beam emitted by the collimating laser 6 is visible, and the position of the collimating laser 6 is adjusted so that the center of the beam spot of the laser beam (i.e. the part of the beam that is the brightest and most concentrated) is completely coincident with the cross center of the No. 1 target 81. When the center of the beam spot of the laser beam is coincident with the cross center of the target, the two points jointly constitute a reference, i.e. the main light path of the debugging optical path. The main light path is a key reference in the process of optical path debugging, which is used to ensure that the subsequent adjustment of the laser beam or the optical path is based on this accurate reference

[0060] S2: The No. 2 target 82 is placed perpendicularly to the main light path so that the cross center of the No. 2 target 82 is coincident with the center of the beam spot of the laser beam.

[0061] Specifically, the No. 2 target 82 is adjusted so that the plane thereof forms an included angle of 90 degrees with the main light path, and the center of the beam spot of the laser beam (i.e. the part of the beam that is the brightest and most concentrated) is completely coincident with the cross center of the No. 2 target 82.

[0062] S3: The half-transmission half-reflection mirror 7 is placed on the main light path, and the position of the half-transmission half-reflection mirror 7 is adjusted so that the center of the beam spot of the transmitted laser beam is coincident with the cross center of the No. 2 target 82.

[0063] Specifically, the half-mirror 7 allows a portion of the light to pass through, while reflecting another portion of the light. When the laser beam passes through the half-mirror 7, a portion of the beam is transmitted, while another portion is reflected. By adjusting the position of the half-mirror 7, it can be observed that the position of the transmitted beam on the 2nd target 82 changes. The goal of the adjustment is to precisely align the center of the spot with the cross center of the 2nd target 82.

[0064] S4: Place the 3rd target 83 in the reflected light path, so that the cross center of the 3rd target 83 coincides with the center of the spot of the reflected beam;

[0065] Specifically, the reflected light path refers to the path formed after the laser beam is reflected by the half-mirror 7, and the 3rd target 83 is placed in the reflected light path. The goal of the adjustment is to precisely align the center of the reflected beam with the cross center of the 3rd target 83.

[0066] S5: Remove the half-mirror 7 from the main light path, and place the off-axis parabolic mirror 221 into the main light path, and adjust the position of the parabolic mirror so that the center of the outgoing beam coincides with the cross center of the 3rd target 83;

[0067] Specifically, after removing the half-mirror 7, the off-axis parabolic mirror 221 is placed into the main light path. The off-axis parabolic mirror 221 is a special optical lens that has the shape of a parabola and is designed to focus incident light parallel to a certain portion of the mirror surface to a point, or to collimate the light emitted by a point source into parallel light. The off-axis parabolic mirror 221 is used to replace the half-mirror 7 to change the propagation path and characteristics of the laser beam. By adjusting the position of the parabolic mirror, it can be observed that the position of the outgoing beam on the 3rd target 83 changes. The goal of the adjustment is to precisely align the center of the outgoing beam with the cross center of the 3rd target 83.

[0068] S6: Remove the collimated laser 6, the 1st target 81, the 2nd target 82, and the 3rd target 83, and the light path adjustment is complete.

[0069] Specifically, when the collimated laser 6 and all the targets are removed, the light path adjustment process is officially completed. The light path has been verified and adjusted according to the design requirements, and can be used for actual applications.

[0070] It will be apparent to those skilled in the art that the application is not limited to the details of the above-exemplified embodiments and that the present application can be implemented in other particular forms without departing from the spirit or essential characteristics thereof. The embodiments should be considered in all respects as illustrative and not restrictive, the scope of the application being indicated by the appended claims rather than by the above description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. No reference herein to any prior art is to be taken as an admission that the application is not entitled to antedate such prior art by virtue of prior application. Any reference to the use of a term in the singular herein shall also be taken to refer to the plural, and vice versa, unless otherwise indicated by context. Any reference to the use of a term in the present application shall be taken to refer to the use of the term in the context of the present application, and not to the use of the term in any other context. Any reference to the use of a term in the present application shall be taken to refer to the use of the term in the context of the present application, and not to the use of the term in any other context.

Claims

1. A device for measuring the far field radiation intensity of a terahertz source, the device comprising: The application relates to a terahertz emission system, a terahertz attenuation system, a terahertz detection system, an extension adapter plate and a computer. The terahertz emission system comprises a measured terahertz radiator. The terahertz attenuation system comprises a variable diaphragm, an optical reflection group and a terahertz attenuator which are installed on the extension adapter plate; the center of the variable diaphragm is located on the same optical axis as the geometric center of the terahertz wave radiator outlet, and the variable diaphragm is used for controlling the radiation amount of the measured terahertz wave radiator; the optical reflection group comprises an off-axis parabolic mirror and n wedge-shaped mirrors; the focal point of the off-axis parabolic mirror coincides with the outlet of the measured terahertz radiator, and the off-axis parabolic mirror is used for converting the terahertz radiation emitted by the measured terahertz radiator into parallel light which is incident on the wedge-shaped mirrors; the n wedge-shaped mirrors are used for attenuating the terahertz radiation and then making the terahertz radiation incident on the terahertz attenuator; and the terahertz attenuator is used for realizing different attenuation multiples. The terahertz detection system comprises a terahertz narrow-band filter, a rotating wheel, a chopper and a terahertz power meter which are installed on the extension adapter plate; the terahertz narrow-band filter is installed on the rotating wheel and is used for controlling the rotating wheel to rotate the corresponding terahertz narrow-band filter into the light path according to the output frequency of the measured terahertz radiator when the radiation intensity is measured, so that the infrared radiation of the measured terahertz wave radiator is segmented and filtered out; the chopper is used for converting continuous terahertz radiation into pulsed terahertz radiation; and the terahertz power meter is used for receiving the pulsed terahertz radiation which is incident on the detection surface of the terahertz power meter and outputting a signal to the computer to calculate the radiation intensity value of the measured terahertz radiator. The terahertz emission system further comprises a rotating table; the outlet of the measured terahertz radiator is located at the center of the rotating table, the terahertz wave radiator outlet position does not change with the rotation of the rotating table, and the focal point of the off-axis parabolic mirror is located at the center of the rotating table.

2. The device according to claim 1, wherein, The extension adapter plate is connected with the rotating table and can rotate synchronously with the rotating table.

3. The device of claim 2, wherein, The aperture of the variable diaphragm can be adjusted to be larger than the outlet aperture of the measured terahertz wave radiator.

4. The device of claim 1, wherein, The surface of the wedge-shaped mirror is coated with a reflective film with a certain reflectivity, which is used for attenuating the terahertz radiation and then making the terahertz radiation incident on the terahertz attenuator.

5. The device of claim 1, wherein, The terahertz attenuator comprises several groups of metal film attenuators with different transmittances, and the several groups of metal film attenuators with different transmittances can be used singly or in combination to realize different attenuation multiples.

6. The device of claim 4, wherein the device is configured to measure the intensity of the terahertz radiation in the far field. The measurement method is applied to the measurement device in any one of claims 1-6 and comprises the following steps.

7. A far-field measurement method for terahertz source radiation intensity, characterized in that, The terahertz radiation power measured by the terahertz power meter is recorded as Pm, the diameter of the diaphragm is adjusted to be D according to the radiation outlet of the measured terahertz radiator during measurement, the transmittance of the terahertz attenuator is recorded as tau1, the transmittance of the terahertz narrow-band filter is recorded as tau2, the reflectivity of each wedge-shaped mirror is R, the number of the wedge-shaped mirrors is n, the distance between the measured terahertz radiator and the variable diaphragm is recorded as L, and the radiation intensity value I of the measured terahertz radiator 1-1 is calculated by using formula (1). The number determination method of the wedge-shaped mirrors comprises the following steps.

8. The method of claim 7, wherein the method further comprises: The light path debugging method is applied to the measurement device in any one of claims 1-6 and comprises the following steps. The output power of the measured terahertz radiator is P O ; the upper limit of the detection power of the terahertz power meter is P max , the attenuation multiple of the terahertz attenuator is a, the reflectivity of each wedge-shaped mirror is R, the number of the required wedge-shaped mirrors is n, and P o ·a·R n ≤P max ; the value of n satisfies When is not an integer, the value of n is rounded up.

9. A method of commissioning an optical circuit, characterized by, ​ S1: Place the No.1 target at the center of the turntable, and make the visible laser beam emitted by the collimating laser incident on the No.1 target. Adjust the position of the collimating laser so that the center of the laser beam spot coincides with the cross center of the No.1 target. The center of the laser beam spot and the cross center of the No.1 target jointly constitute the main light path of the debugging light path; S2: Place the No.2 target perpendicular to the main light path so that the cross center of the No.2 target coincides with the center of the laser beam spot; S3: Place the semi-transparent half-mirror on the main light path, and adjust the position of the semi-transparent half-mirror so that the center of the transmitted laser beam spot coincides with the cross center of the No.2 target; S4: Place the No.3 target in the reflected light path so that the cross center of the No.3 target coincides with the center of the reflected light path; S5: Move the semi-transparent half-mirror out of the main light path, and place the off-axis parabolic mirror into the main light path. Adjust the position of the parabolic mirror so that the center of the outgoing light beam coincides with the cross center of the No.3 target; S6: Remove the collimating laser, the No.1 target, the No.2 target and the No.3 target, and the light path debugging is completed.

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