CN-113985443-B - Terahertz wave imaging system and method

CN113985443BCN 113985443 BCN113985443 BCN 113985443BCN-113985443-B

Abstract

The invention provides a terahertz wave imaging system and a terahertz wave imaging method, wherein the system comprises a terahertz detector (A) for detecting a terahertz modulated optical signal and sampling the terahertz modulated optical signal by using a demodulation signal to obtain a sampling signal, a CSA integration module (B) for sequentially carrying out integration amplification on the sampling signal to obtain a photocurrent signal, and a signal processing module (C) for processing the photocurrent signal to obtain a sampling value, calculating flight time and depth information of the terahertz modulated optical signal according to the sampling value to obtain imaging by using the flight time and the depth information, wherein the demodulation signal and the terahertz modulated optical signal have phase offset. The terahertz wave imaging system can be manufactured on the same CMOS chip, has the advantages of simple design principle, high precision and low cost, and is easy for large-scale integration.

Inventors

LIU LIYUAN
LIU MIN
LIU JIAN
WU NANJIAN

Assignees

中国科学院半导体研究所
中国科学院半导体研究所

Dates

Publication Date: 20260421
Application Date: 20211027
Priority Date: 20211027

Claims (10)

1. A terahertz wave imaging system, characterized by comprising: The terahertz detector (A) is used for detecting terahertz modulated optical signals, and carrying out different-phase sampling on the terahertz modulated optical signals by utilizing demodulation signals to obtain a plurality of sampling signals, wherein the demodulation signals are square waves, and the frequency of the demodulation signals is consistent with that of the terahertz modulated optical signals; The CSA integration module (B) is used for sequentially carrying out integration amplification on the plurality of sampling signals to obtain a plurality of integrated and amplified sampling signals; The signal processing module (C) is used for processing the plurality of integrated and amplified sampling signals to obtain sampling values, calculating the flight time and depth information of the terahertz modulation optical signals according to the sampling values, and imaging by utilizing the flight time and depth information; Wherein the demodulation signal has a phase offset from the terahertz modulated optical signal; The CSA integration module (B) comprises four parallel CSA integration circuit units (D), each CSA integration circuit unit (D) is connected with the terahertz detector (A) through a gating switch (E), and the CSA integration circuit unit (D) comprises: An amplifier (D1), a reset switch (D2) and a variable integrating capacitor (D3) which are connected in parallel with each other; The negative input end of the amplifier (D1) is connected with the gating switch (E), the positive input end of the amplifier is connected with a reference voltage (V ref ), and the variable integrating 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 integrating circuit units (D) are used for time-sharing integration and amplification of a plurality of sampling signals with phase offsets of 0 DEG, 90 DEG, 180 DEG and 270 DEG in sequence.
2. The terahertz wave imaging system according to claim 1, wherein the terahertz detector (a) includes: an on-chip antenna (A1), a transmission line (A2) and a field effect transistor (M1); The on-chip antenna (A1) is used for receiving the terahertz modulation optical signal radiated by the emission light source, the transmission line (A2) is used for transmitting the terahertz modulation optical signal to the field effect transistor (M1), and the field effect transistor (M1) is used for detecting and sampling the terahertz modulation optical signal.
3. Terahertz wave imaging system according to claim 2, characterized in that the demodulation signal is loaded on the gate of the field effect transistor (M1).
4. The terahertz-wave imaging system according to claim 2, wherein the on-chip antenna (A1) is any one of a dipole antenna or a loop antenna.
5. Terahertz-wave imaging system according to claim 2, characterized in that the on-chip antenna (A1) is a butterfly antenna.
6. Terahertz wave imaging system according to claim 2, characterized in that the on-chip antenna (A1) is a patch antenna.
7. The terahertz wave imaging system according to claim 1, wherein the terahertz modulated optical signal is a terahertz wave amplitude modulated signal to which a continuous wave or pulse wave modulated signal is applied.
8. The terahertz wave imaging system according to claim 1, wherein the signal processing module (C) is constituted by a digital unit and is further configured to store the integrated and amplified sampling signal.
9. A terahertz wave imaging method, characterized by comprising: Detecting a terahertz modulated optical signal, and carrying out different phase sampling on the terahertz modulated optical signal by utilizing a demodulation signal to obtain a plurality of sampling signals, wherein the demodulation signal is a square wave, and the frequency of the demodulation signal is consistent with the frequency of the terahertz modulated optical signal; sequentially integrating and amplifying the plurality of sampling signals by using a CSA integrating module (B) to obtain a plurality of integrated and amplified sampling signals; processing the plurality of integrated and amplified sampling signals to obtain sampling values, calculating flight time and depth information of the terahertz modulated optical signals according to the sampling values, and imaging by utilizing the flight time and depth information; Wherein the demodulation signal has a phase offset from the terahertz modulated optical signal; The CSA integration module (B) comprises four parallel CSA integration circuit units (D), each CSA integration circuit unit (D) is connected with the terahertz detector (A) through a gating switch (E), and the CSA integration circuit units (D) comprise: An amplifier (D1), a reset switch (D2) and a variable integrating capacitor (D3) which are connected in parallel with each other; The negative input end of the amplifier (D1) is connected with the gating switch (E), the positive input end of the amplifier is connected with a reference voltage (V ref ), and the variable integrating 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 integrating circuit units (D) are used for time-sharing integration and amplification of a plurality of sampling signals with phase offsets of 0 DEG, 90 DEG, 180 DEG and 270 DEG in sequence.
10. The terahertz wave imaging method according to claim 9, wherein the sampling the terahertz modulated optical signal with a demodulation signal in different phases includes sampling in four phases or sampling in two phases.

Description

Terahertz wave imaging system and method Technical Field The disclosure relates to the technical field of TOF three-dimensional imaging, in particular to a terahertz wave imaging system and method. Background The TOF three-dimensional imaging technique acquires distance information (TOF, time of Flight) by measuring the Time of Flight of light. Terahertz wave signals are of great research significance as the last window of research in the electromagnetic spectrum, and in addition, a plurality of unique properties of the terahertz wave signals. Terahertz waves detected by the prior art are usually weak and are easily submerged by 1/f noise and white noise, and the changing frequency is too high to be easily captured. In an ideal case, the signal can be detected by using the detection circuit as long as the optical radiation signal exists, but when the detected signal is very weak, the condition that the signal cannot be detected often occurs, so that the terahertz wave reading system with simple structure, strong adaptability and high sensitivity and the three-dimensional imaging system based on the system have great research significance. Disclosure of Invention First, the technical problem to be solved Aiming at the prior technical problems, the present disclosure provides a terahertz wave imaging system and a terahertz wave imaging method, which are used for at least partially solving the technical problems. (II) technical scheme The invention provides a terahertz wave imaging system which comprises a terahertz detector A, a CSA integration module B, a signal processing module C and a signal processing module C, wherein the terahertz detector A is used for detecting a terahertz modulated optical signal and utilizing a demodulation signal to sample the terahertz modulated optical signal to obtain a sampling signal, the CSA integration module B is used for sequentially carrying out integration amplification on the sampling signal to obtain a photocurrent signal, the signal processing module C is used for processing the photocurrent signal to obtain a sampling value, flight time and depth information of the terahertz modulated optical signal are obtained through calculation according to the sampling value, and imaging is carried out by utilizing the flight time and the depth information, wherein the demodulation signal and the terahertz modulated optical signal have phase offset. Optionally, the terahertz detector A comprises an on-chip antenna A1, a transmission line A2 and a field effect transistor M1, wherein the on-chip antenna A1 is used for receiving a terahertz modulation optical signal radiated by an emission light source, the transmission line A2 is used for transmitting the terahertz modulation optical signal to the field effect transistor M1, and the field effect transistor M1 is used for detecting and sampling the terahertz modulation optical signal. Optionally, a demodulation signal is loaded on the gate of the field effect transistor M1, and the demodulation signal is a square wave. Optionally, the frequency of the demodulation signal coincides with the frequency of the terahertz modulated optical signal. Optionally, the on-chip antenna A1 is any one of a dipole antenna, a loop antenna, a butterfly antenna, or a patch antenna. Optionally, the CSA integrating module B comprises four parallel CSA integrating circuit units D, each CSA integrating circuit unit D is connected with the terahertz detector A through a gating switch E, the CSA integrating circuit unit D comprises an amplifier D1, a reset switch D2 and a variable integrating capacitor D3 which are mutually connected in parallel, wherein the negative input end of the amplifier D1 is connected with the gating switch E, the positive input end of the amplifier D1 is connected with a reference voltage V ref, and the variable integrating capacitor D3 is used for integrating and amplifying a sampling signal according to the level value of the reset switch D2. Alternatively, the terahertz modulated optical signal is a terahertz wave amplitude modulated signal to which a continuous wave or pulse wave modulated signal is applied. Optionally, the signal processing module C is formed by a digital unit and is also used for storing the photocurrent signal. The terahertz wave imaging method comprises the steps of detecting a terahertz modulated light signal, sampling the terahertz modulated light signal by using a demodulation signal to obtain a sampling signal, sequentially carrying out integral amplification on the sampling signal to obtain a photocurrent signal, processing the photocurrent signal to obtain a sampling value, calculating the flight time and depth information of the terahertz modulated light signal according to the sampling value to obtain the flight time and depth information of the terahertz modulated light signal, and imaging by using the flight time and depth information, wherein the demodulation signal and the terahertz modulated