Terahertz wave imaging system and method

Abstract

The present disclosure provides a terahertz wave imaging system and method, the system comprising: a terahertz detector (A) for detecting a terahertz modulated light signal and sampling the terahertz modulated light signal by using a demodulation signal to obtain a sampling signal; a CSA integration module (B) for sequentially integrating and amplifying the sampling signal to obtain a photocurrent signal; a signal processing module (C) for processing the photocurrent signal to obtain a sampling value, calculating the time of flight and depth information of the terahertz modulated light signal according to the sampling value, and imaging by using the time of flight and depth information; wherein the demodulation signal has a phase offset with the terahertz modulated light signal. The terahertz wave imaging system of the present disclosure can be made on the same CMOS chip, has simple design principle, high precision, low cost, and is easy to mass integrate.

Description

Technical Field

[0001] This disclosure relates to the field of TOF three-dimensional imaging technology, and in particular to a terahertz wave imaging system and method. Background Technology

[0002] Time-of-flight (TOF) 3D imaging technology obtains distance information by measuring the time of flight of light. Terahertz wave signals, as the last window for research in the electromagnetic spectrum, coupled with their many unique properties, are of significant research importance.

[0003] Existing technologies typically detect very weak terahertz waves, which are easily drowned out by 1 / f noise and white noise, and their high-frequency variations make them difficult to capture. Ideally, any optical radiation signal should be detectable using a detection circuit. However, when the detected signal is extremely weak, it often fails to be detected. Therefore, designing a simple, adaptable, and highly sensitive terahertz wave readout system and a three-dimensional imaging system based on this system is of great research significance. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] To address the existing technical problems, this disclosure provides a terahertz wave imaging system and method, which at least partially solves the above-mentioned technical problems.

[0006] (II) Technical Solution

[0007] This disclosure provides a terahertz wave imaging system, comprising: a terahertz detector A for detecting terahertz modulated optical signals and sampling the terahertz modulated optical signals using a demodulated signal to obtain a sampled signal; a CSA integration module B for sequentially integrating and amplifying the sampled signal to obtain a photocurrent signal; and a signal processing module C for processing the photocurrent signal to obtain sampled values, calculating the time-of-flight and depth information of the terahertz modulated optical signal based on the sampled values, and using the time-of-flight and depth information for imaging; wherein the demodulated signal and the terahertz modulated optical signal have a phase shift.

[0008] Optionally, the terahertz detector A includes: an on-chip antenna A1, a transmission line A2, and a field-effect transistor M1; wherein, the on-chip antenna A1 is used to receive the terahertz modulated optical signal radiated by the transmitting light source, the transmission line A2 is used to transmit the terahertz modulated optical signal to the field-effect transistor M1, and the field-effect transistor M1 is used to detect and sample the terahertz modulated optical signal.

[0009] Optionally, a demodulation signal is loaded on the gate of the field-effect transistor M1, and the demodulation signal is a square wave.

[0010] Optionally, the frequency of the demodulated signal is the same as the frequency of the terahertz modulated optical signal.

[0011] Optionally, the on-chip antenna A1 can be any one of a dipole antenna, a loop antenna, a butterfly antenna, or a patch antenna.

[0012] Optionally, the CSA integration module B includes four parallel CSA integration circuit units D. Each CSA integration circuit unit D is connected to the terahertz detector A through a selection switch E. The CSA integration circuit unit D includes: an amplifier D1 connected in parallel, a reset switch D2, and a variable integrating capacitor D3; wherein, the negative input terminal of the amplifier D1 is connected to the selection switch E, and the positive input terminal is connected to a reference voltage V. ref The variable integrating capacitor D3 is used to integrate and amplify the sampled signal based on the level value of the reset switch D2.

[0013] Optionally, the terahertz modulated optical signal is a terahertz wave amplitude-modulated signal to which a continuous wave or pulse wave modulation signal is applied.

[0014] Optionally, the signal processing module C is composed of digital units and is also used to store photocurrent signals.

[0015] Another aspect of this disclosure provides a terahertz wave imaging method, comprising: detecting a terahertz modulated optical signal and sampling the terahertz modulated optical signal using a demodulated signal to obtain a sampled signal; sequentially integrating and amplifying the sampled signal to obtain a photocurrent signal; processing the photocurrent signal to obtain sampled values, calculating the time-of-flight and depth information of the terahertz modulated optical signal based on the sampled values, and using the time-of-flight and depth information for imaging; wherein the demodulated signal and the terahertz modulated optical signal have a phase shift.

[0016] Optionally, sampling the terahertz modulated optical signal using the demodulated signal includes performing four-phase sampling or two-phase sampling.

[0017] (III) Beneficial Effects

[0018] This disclosure provides a terahertz wave imaging system based on ITOF technology. By sampling at different phases and then performing four-channel parallel amplification and detection, it can read out weak terahertz wave amplitude-modulated signals, thereby obtaining high pixel resolution and high relative distance measurement accuracy for imaging. The system has a stable readout bias voltage applied to the gate of the field-effect transistor M1, which makes the input impedance of the CSA integrator module very small and unaffected by the input terahertz photocurrent, resulting in high sensitivity.

[0019] The terahertz wave imaging system disclosed herein can be fabricated on the same CMOS chip, with a simple design principle, high precision, low cost, and easy large-scale integration. Attached Figure Description

[0020] The above and other objects, features and advantages of this disclosure will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0021] Figure 1 A schematic diagram of a terahertz wave imaging system according to an embodiment of the present disclosure is shown.

[0022] Figure 2 A schematic diagram illustrating a four-phase sampling operation based on continuous wave modulation according to an embodiment of the present disclosure is shown.

[0023] Figure 3 A schematic diagram illustrating a pulse-wave modulation-based dual-phase sampling operation according to an embodiment of the present disclosure is shown.

[0024] Figure 4 A flowchart illustrating a terahertz wave imaging method according to an embodiment of the present disclosure is shown schematically.

[0025] [Explanation of Labels in the Attached Image]

[0026] A-Terahertz Detector

[0027] A1-On-chip antenna

[0028] A2-Transmission Line

[0029] B-CSA Integral Module

[0030] C-Signal Processing Module

[0031] D-CSA Integrating Circuit Unit

[0032] D1 - Amplifier

[0033] D2 - Reset Switch

[0034] D3 - Variable Integral Capacitor

[0035] E-select switch

[0036] M1 - Field-Effect Transistor

[0037] V ref -Reference voltage Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.

[0039] It should be noted that similar or identical parts are referred to by the same reference numerals in the accompanying drawings or description. The technical features of the various embodiments exemplified in the specification can be freely combined to form new solutions without conflict. Furthermore, each claim can stand alone as an embodiment, or the technical features in the various claims can be combined to form new embodiments. In the drawings, the shape or thickness of the embodiments may be enlarged and indicated in a simplified or convenient manner. Moreover, elements or implementations not shown or described in the drawings are those known to those skilled in the art. Additionally, although this document provides examples of parameters containing specific values, it should be understood that the parameters need not be exactly equal to the corresponding values, but can approximate the corresponding values ​​within acceptable error tolerances or design constraints.

[0040] Unless there are technical obstacles or contradictions, the various embodiments described above in this disclosure can be freely combined to form other embodiments, all of which are within the protection scope of this disclosure.

[0041] Although this disclosure has been described in conjunction with the accompanying drawings, the embodiments disclosed in the drawings are intended to illustrate preferred embodiments of this disclosure and should not be construed as limiting the disclosure. The dimensions in the drawings are merely illustrative and should not be construed as limiting the disclosure.

[0042] While some embodiments of the general concept of this disclosure have been shown and described, those skilled in the art will understand that changes may be made to these embodiments without departing from the principles and spirit of the general concept of this disclosure, the scope of which is defined by the claims and their equivalents.

[0043] Figure 1 A schematic diagram of a terahertz wave imaging system according to an embodiment of the present disclosure is shown.

[0044] According to embodiments of this disclosure, such as Figure 1 As shown, a terahertz imaging system includes, for example, a terahertz detector A, a gating switch E, a multi-channel parallel CSA integrator module B, and a signal processing module C. The terahertz detector A detects terahertz light signals and samples them at different phases. Then, it is connected to the multi-channel CSA integrator module via the gating switch E to integrate and amplify the multiple sampled photocurrent signals. Subsequently, the signal processing module C processes and stores the various signals read from the multi-channel CSA integrator module, thereby calculating the time-of-flight and depth information of the terahertz light signal. The gating switch E can, for example, be controlled by an external FPGA (Field Programmable Gate Array).

[0045] According to embodiments of this disclosure, the terahertz detector A may be a single detector or an array of detectors composed of such single detectors. A single terahertz detector may include, for example, an on-chip antenna A1, a transmission line A2, and a field-effect transistor M1. The on-chip antenna A1 is used to receive terahertz modulated optical signals, preferably with a high radiation efficiency and wide bandwidth antenna design. The transmission line A2 connects the on-chip antenna A1 to the source of the field-effect transistor M1, achieving impedance matching between the on-chip antenna A1 and the source of the field-effect transistor M1 to maximize transmission efficiency. The field-effect transistor M1 is used to detect and sample the terahertz modulated optical signal. A suitable periodic square wave signal with the same frequency as the terahertz modulated optical signal is loaded onto the gate of the field-effect transistor M1 to obtain the maximum field-effect transistor response and achieve different phase sampling during operation. The drain of the field-effect transistor M1 is connected to a gating switch E for outputting the terahertz optical signal.

[0046] According to embodiments of this disclosure, such as Figure 1 As shown, the CSA integration module B includes, for example, four parallel CSA integration circuit units D arranged in channels 1 to 4. Each CSA integration circuit unit D is connected in series with a gating switch E, which is connected to the terahertz detector A. The four gating switches provide low on-resistance for the MOSFET or a combination of MOSFET and other devices, and can also serve as signal control terminals for different phase sampling. tof1 to I tof4 The first integrated amplified photocurrent signal output from the first CSA integrating circuit unit is connected to the fourth integrated amplified photocurrent signal output from the fourth CSA integrating circuit unit. Each CSA integrating circuit unit D includes, for example, an amplifier D1 connected in parallel, such as a charge-sensitive amplifier (CSA), a reset switch D2, and a variable integrating capacitor D3. The negative input terminal of amplifier D1 is connected to a gating switch E, one end of the reset switch D2, and one end of the variable integrating capacitor D3; the positive input terminal is connected to a reference voltage V. ref The other end of reset switch D2 and the other end of variable integrating capacitor D3 are both connected to the output of amplifier D1. The output of amplifier D1 outputs the integrated amplified photocurrent signal I. tofThe signal is transferred to signal processing module C. When reset switch D2 is high, it is closed, and the CSA integrator unit D is in the reset phase, with its negative input terminal connected to its output terminal, and the variable integrating capacitor D3 short-circuited. When reset switch D2 is low, it is open, and the CSA integrator unit D is in the integration phase, performing integration and amplification of the input photocurrent signal. The input transconductance of the CSA integrator unit D should be as high as possible. For example, a stable bias voltage can be applied to the gate of the field-effect transistor M1 to reduce the thermal noise caused by the detector leakage current. The CSA integrator unit D is a variable gain integrator, and the variable integrating capacitor D3 can be adjusted according to the magnitude of the input modulated photocurrent, adapting to detection signals of different light intensities and increasing the adaptability of the readout system.

[0047] Figure 2 A schematic diagram illustrating a four-phase sampling operation based on continuous wave modulation according to an embodiment of the present disclosure is shown.

[0048] According to embodiments of this disclosure, the signal processing module C includes, for example, a digital processing unit that processes multiple integrated amplified signals to obtain the time-of-flight and depth information of the reflected light signal. Figure 2 As shown, T tof The time of flight is V. The transmitted signal is a terahertz-modulated optical signal, and the reflected signal is the reflection of the terahertz-modulated optical signal by the on-chip antenna. g0 ~V g3 The first to fourth sampled signals have sampled values ​​S0 to S3 respectively, with phase offsets from the carrier signal of 0°, 90°, 180°, and 270° respectively. Specifically, the first sampled signal V has a phase offset of 0°. g0 The second sampled signal V with a phase offset of 90° g1 The third sampled signal V with a phase offset of 180° g2 The fourth sampled signal V with a phase offset of 270° g3 Regarding V g0 The sampled value S0 is obtained, for V g1 The sampled value S1 is obtained, for V g2 The sampled value S2 is obtained, for V g3 The sampled value S3 is obtained. The flight time T of the obtained terahertz wave signal is... tof The depth information D is shown in equations (1) to (2).

[0049]

[0050]

[0051] Where T represents the period of transmitting a single-frequency signal, T tof Indicates flight time, Let D represent the calculated distance, and c be the signal propagation speed, approximating the speed of light, where c is the corresponding delay phase. Assume the terahertz wave signal simulates a signal with a certain amplitude V. c and fixed frequency w THz For a single-frequency signal, the terahertz wave signal v c It can be represented by equation (3).

[0052] v c (t)=V c cosw THz t (3)

[0053] t represents time. The modulated signal applied to the terahertz wave simulates a signal with a certain amplitude V. m The continuous wave amplitude-modulated signal with a fixed frequency w can be represented by equation (4).

[0054] v m (t)=V m coswt (4)

[0055] The terahertz signal can be modulated by an amplitude modulation signal to obtain the transmitted signal represented by equation (5).

[0056] v(t) = V c (1+V m coswt)cosw THz t (5)

[0057] The reflected signal r(t) is an envelope amplitude modulated signal with the same modulation frequency as the transmitted signal and a certain phase delay and amplitude attenuation, which can be represented by equation (6).

[0058]

[0059] Where a is the amplitude attenuation factor of the reflected terahertz wave modulation signal. This represents the phase delay of the reflected signal as it propagates along the reflection path. Utilizing the nonlinear characteristics of the MOS element itself, a nonlinear transformation of the amplitude-modulated signal is performed, eliminating the need for a local carrier signal as a coherent signal, thus achieving noncoherent demodulation of the amplitude-modulated wave. Assuming the I / V transfer characteristic of the low-bias MOS transistor is a square relationship, the signal after the reflected signal passes through the MOS transistor can be expressed by equation (7).

[0060]

[0061] Where b is the square factor, since the terahertz frequency component and the harmonic component of the modulation frequency will be directly filtered out in the subsequent readout processing, equation (7) can be approximately expressed as follows:

[0062]

[0063] Among them, A=ba 2 V c 2 V m B represents the offset caused by background light and other factors in the imaging system, and it is assumed that this offset remains constant during the imaging process. The gate of the MOS transistor is controlled by a periodic gating signal with the same frequency as the reflected signal to sample the reflected signal. The gating function of the sampled signal can be represented by equation (9).

[0064]

[0065] The process of cross-correlation sampling using reflected signals can be expressed by equation (10).

[0066]

[0067] According to embodiments of this disclosure, the carrier modulation frequency w is, for example, 20MHz, and the four different sampling signals V of the MOS transistor gate... g0 ~V g3 The frequency is, for example, 20MHz, and has a certain phase offset from the modulating signal. Four sampling control signal values ​​are selectively selected every 1s, and the sampled values ​​obtained after sampling by the field effect transistor M1 in the terahertz detector are S0, S1, S2, and S3, respectively. We select the signal values ​​under four phase offset conditions of 0°, 90°, 180° and 270° from the transmitted signal, and we can obtain a set of formulas as shown in equations (11) to (14).

[0068]

[0069]

[0070]

[0071]

[0072] The signals are then sequentially input into a four-channel CSA integrator module for integration and amplification. Finally, the digital processing unit processes the four integrated signals to obtain the corresponding delayed phase. The amplitude A and offset B of the reflected signal can be expressed as follows:

[0073]

[0074]

[0075]

[0076] Figure 3 A schematic diagram illustrating a pulse-wave modulation-based dual-phase sampling operation according to an embodiment of the present disclosure is shown.

[0077] According to embodiments of this disclosure, such as Figure 3 As shown, the terahertz wave imaging system disclosed herein can also sample terahertz modulated optical signals based on pulse-wave modulation dual-phase sampling, specifically the first sampling signal V with a phase offset of 0°. g0 The third sampled signal V with a phase offset of 180° g2 Regarding V g0 The sampled value S0 is obtained, for V g2 The sampled value S2 is obtained, and the corresponding terahertz wave signal flight time T is obtained. tof The depth information D is represented as follows:

[0078]

[0079]

[0080] Where T represents the period of transmitting a single-frequency signal, T tof Let V represent the flight time, D represent the calculated distance, c represent the signal propagation speed (approximately the speed of light), and α represent the duty cycle of the pulse wave. Assume that the terahertz wave signal simulates a signal with a certain amplitude V. c and fixed frequency w THz The single-frequency signal can be represented by equation (3). The modulation signal loaded onto the terahertz wave signal simulates a signal with a certain amplitude V. m A square wave amplitude-modulated signal with a fixed frequency w and a certain duty cycle α can be represented by equation (20).

[0081]

[0082] The terahertz signal can be modulated by an amplitude modulation signal to obtain the transmitted signal represented by equation (21).

[0083]

[0084] The reflected signal r(t) is an envelope amplitude modulated signal with the same modulation frequency as the transmitted signal and a certain phase delay and amplitude attenuation, which can be represented by equation (22).

[0085] r(t)=av(t-Δt=v c (t)·v m (t-Δt) (22)

[0086] Where 'a' is the amplitude attenuation factor of the reflected terahertz wave modulation signal, and 'Δt' is the time delay of the reflected signal propagating along the reflection path. Based on the nonlinear I / V characteristics of the MOS transistor, the detection signal is obtained as follows:

[0087] i D (t)=βr 2 (t)=0.5βa 2 V c 2 v m 2 (t-Δt)[1+cos2w THz t] (23)

[0088] Where β is a scaling factor, with a value of 0 to 1. Since the terahertz frequency components and the harmonic components of the modulation frequency are directly filtered out in the subsequent readout processing, equation (21) can be approximately expressed as follows:

[0089]

[0090] Where B is the offset caused by background light and other factors in the imaging system, and it is assumed that this offset remains constant during the imaging process. The gate of the MOS transistor is controlled by a periodic pulse wave gating signal with the same frequency as the reflected signal to sample the reflected signal. The gating function of the sampled signal can be represented by equation (25).

[0091]

[0092] The process of cross-correlation sampling using reflected signals can be represented as follows:

[0093]

[0094] According to embodiments of this disclosure, the carrier modulation frequency w is, for example, 20MHz, and the two different sampling signals V of the MOS transistor gate... g0 V g2 The frequency is, for example, 20MHz, and has a certain phase offset from the modulation signal. In this embodiment, two sampling control signal values ​​are selectively selected every 1s, and the sampled values ​​obtained after sampling by the field-effect transistor M1 in the terahertz detector are S0 and S2, respectively. Under the condition of having two phase offsets of 0° and 180° from the transmitted signal, the signal values ​​are selected, and a set of formulas as shown in equations (27) to (28) can be obtained.

[0095] S0=(0.5βa 2 V c 2 V m 2 +B)(αT-T tof (27)

[0096] S2=(0.5βa 2 V c 2 V m 2 +B)T tof (28)

[0097] The signals are then sequentially input into a four-channel CSA integrator module, with two channels bypassed, for integration and amplification. Finally, the two integrated signals are processed by a digital processing unit to obtain the flight time T of the corresponding terahertz wave signal. tof And depth information D.

[0098] It is worth noting that when the duty cycle α of the pulse wave amplitude modulation signal exceeds 0.5, its analysis process is consistent with that of continuous wave analysis.

[0099] Figure 4 A flowchart illustrating a terahertz wave imaging method according to an embodiment of the present disclosure is shown schematically.

[0100] According to embodiments of this disclosure, such as Figure 4 As shown, terahertz wave imaging methods include, for example:

[0101] S401 detects the terahertz modulated optical signal and samples it using the demodulated signal to obtain a sampled signal. The demodulated signal and the terahertz modulated optical signal have a phase shift.

[0102] S402 sequentially integrates and amplifies the sampled signal to obtain the photocurrent signal.

[0103] S403 processes the photocurrent signal to obtain sampled values, calculates the time of flight and depth information of the terahertz modulated optical signal based on the sampled values, and uses the time of flight and depth information for imaging.

[0104] In summary, this disclosure proposes a terahertz wave imaging system based on ITOF technology, which can be applied to the effective readout of reflected signals in three-dimensional ITOF terahertz wave imaging technology, thereby obtaining time-of-flight and depth information, while adapting to signal readout with different light intensities. This disclosure integrates the terahertz detector, CSA integration module, and signal processing module on the same chip, which has the advantages of system simplicity, high accuracy, and low cost.

[0105] Details not covered in the method embodiment section are similar to those in the device embodiment section; please refer to the device embodiment section for further details, which will not be repeated here.

[0106] It should be understood that the specific order or hierarchy of steps in the disclosed process is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process may be rearranged without departing from the scope of this disclosure. The appended method claims provide elements of various steps in an exemplary order and are not intended to limit the scope to a specific order or hierarchy.

[0107] It should also be noted that the directional terms mentioned in the embodiments, such as "up," "down," "front," "back," "left," and "right," are only for reference to the directions in the accompanying drawings and are not intended to limit the scope of protection of this disclosure. Throughout the drawings, the same elements are represented by the same or similar reference numerals. Conventional structures or constructions will be omitted when they may cause confusion in understanding this disclosure. Furthermore, the shapes, sizes, and positional relationships of the components in the drawings do not reflect their actual size, scale, or actual positional relationships.

[0108] In the detailed description above, various features are combined together in a single embodiment to simplify this disclosure. This approach to disclosure should not be construed as reflecting an intention that embodiments of the claimed subject matter require more features than are explicitly stated in each claim. Rather, as reflected in the appended claims, this disclosure is in a state of having fewer features than all of the features of the single disclosed embodiment. Therefore, the appended claims are hereby explicitly incorporated into the detailed description, with each claim representing a separate preferred embodiment of this disclosure.

[0109] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this disclosure, "a plurality of" means at least two, such as two, three, etc., unless otherwise expressly specified. The term "comprising" as used in the specification or claims is interpreted in a manner similar to the term "including," as "including" is used as a conjunction in the claims. The use of any term "or" in the specification or claims is intended to mean "non-exclusive or."

[0110] The specific embodiments described above further illustrate the purpose, technical solutions, and beneficial effects of this disclosure. It should be understood that the above descriptions are merely specific embodiments of this disclosure and are not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A terahertz wave imaging system, characterized by, include: A terahertz detector (A) is used to detect terahertz modulated optical signals and to sample the terahertz modulated optical signals at different phases using demodulated signals to obtain multiple sampled signals. The demodulated signals are square waves and the frequency of the demodulated signals is consistent with the frequency of the terahertz modulated optical signals. The CSA integration module (B) is used to sequentially integrate and amplify the multiple sampled signals to obtain multiple integrated and amplified sampled signals. The signal processing module (C) is used to process the multiple integrated and amplified sampled signals to obtain sampled values, calculate the time of flight and depth information of the terahertz modulated optical signal based on the sampled values, and use the time of flight and depth information for imaging. The demodulated signal and the terahertz modulated optical signal have a phase shift; The CSA integration module (B) includes four parallel CSA integration circuit units (D), each of which is connected to the terahertz detector (A) via a selector switch (E). Each CSA integration circuit unit (D) includes: Amplifier (D1), reset switch (D2), and variable integrating capacitor (D3) connected in parallel. The negative input end of the amplifier (D1) is connected with the gate switch (E), and the positive input end is connected with a reference voltage (V ref ). The variable integration capacitor (D3) is used for integrating and amplifying the sampling signal according to the level value of the reset switch (D2). The four parallel CSA integrator circuit units (D) are used for time-division integration amplification of multiple sampled signals with phase offsets of 0°, 90°, 180° and 270° respectively.

2. The terahertz wave imaging system of claim 1, wherein, The terahertz detector (A) includes: On-chip antenna (A1), transmission line (A2), and field-effect transistor (M1); The on-chip antenna (A1) is used to receive the terahertz modulated optical signal radiated by the transmitting light source, the transmission line (A2) is used to transmit the terahertz modulated optical signal to the field-effect transistor (M1), and the field-effect transistor (M1) is used to detect and sample the terahertz modulated optical signal.

3. The terahertz wave imaging system of claim 2, wherein, The demodulation signal is loaded onto the gate of the field-effect transistor (M1).

4. The terahertz wave imaging system of claim 2, wherein, The on-chip antenna (A1) can be either a dipole antenna or a loop antenna.

5. The terahertz wave imaging system of claim 2, wherein, The on-chip antenna (A1) is a butterfly antenna.

6. The terahertz wave imaging system of claim 2, wherein, The on-chip antenna (A1) is a patch antenna.

7. The terahertz wave imaging system of claim 1, wherein, The terahertz modulated optical signal is a terahertz amplitude-modulated signal to which a continuous wave or pulse wave modulation signal is applied.

8. The terahertz wave imaging system of claim 1, wherein, The signal processing module (C) consists of digital units and is also used to store the integrated and amplified sampled signal.

9. A terahertz wave imaging method characterized by comprising: include: The terahertz modulated optical signal is detected, and the demodulated signal is used to sample the terahertz modulated optical signal at different phases to obtain multiple sampled signals. The demodulated signal is a square wave, and the frequency of the demodulated signal is consistent with the frequency of the terahertz modulated optical signal. The multiple sampled signals are sequentially integrated and amplified using the CSA integration module (B) to obtain multiple integrated and amplified sampled signals; The sampled signals after multiple integral amplifications are processed to obtain sampled values. The time of flight and depth information of the terahertz modulated optical signal are calculated based on the sampled values, and the time of flight and depth information are used for imaging. The demodulated signal and the terahertz modulated optical signal have a phase shift; The CSA integration module (B) includes four parallel CSA integration circuit units (D), each of which is connected to the terahertz detector (A) via a selector switch (E). Each CSA integration circuit unit (D) includes: Amplifier (D1), reset switch (D2), and variable integrating capacitor (D3) connected in parallel. The negative input end of the amplifier (D1) is connected with the gate switch (E), and the positive input end is connected with a reference voltage (V ref ). The variable integration capacitor (D3) is used for integrating and amplifying the sampling signal according to the level value of the reset switch (D2). The four parallel CSA integrator circuit units (D) are used for time-division integration amplification of multiple sampled signals with phase offsets of 0°, 90°, 180° and 270° respectively.

10. The terahertz wave imaging method according to claim 9, wherein, The process of sampling the terahertz modulated optical signal using the demodulated signal at different phases includes performing four-phase sampling or two-phase sampling.

Images