Array type millimeter wave terahertz near-field imaging device and method based on modulation and demodulation

Abstract

The invention discloses an array type millimeter wave terahertz near-field imaging device and method based on modulation and demodulation, and belongs to millimeter wave terahertz imaging. According to the modulation-demodulation-based array type millimeter wave terahertz near-field imaging technology provided by the invention, the scanning imaging range and speed are expanded by adopting a probe array, and meanwhile, modulation and demodulation of millimeter wave terahertz waves are realized by adopting different excitation frequencies for each probe, so that terahertz near-field imaging of N probes can be realized at the same time; therefore, the scanning speed and the scanning range of near-field imaging can be improved.

Description

Technical Field

[0001] The present invention belongs to the field of millimeter wave terahertz imaging, and in particular relates to an array type millimeter wave terahertz near-field imaging device and method based on modulation and demodulation. Background Art

[0002] At present, researchers have developed a terahertz near-field imaging method based on probe scattering. By using a single probe to tap and vibrate to modulate the terahertz near-field electromagnetic wave, and receiving the terahertz wave scattered by the probe in the far field, super-resolution imaging of the sample to be tested is achieved. Millimeter-wave terahertz has advantages such as strong penetration and has important applications in fields such as millimeter-wave terahertz imaging. Compared with millimeter-wave terahertz far-field imaging technology, millimeter-wave terahertz near-field imaging can break through the diffraction limit constraint and achieve super-resolution imaging.

[0003] The current millimeter-wave terahertz near-field imaging technology can only realize the scanning imaging of a single near-field probe, and the scanning imaging range and scanning imaging speed are limited. Therefore, it is urgent to develop a millimeter-wave terahertz near-field imaging detection method that can improve the scanning speed and scanning range. Summary of the invention

[0004] In view of the above technical problems existing in the prior art, the present invention proposes an array-type millimeter-wave terahertz near-field imaging device and method based on modulation and demodulation, which has a reasonable design, overcomes the shortcomings of the prior art, and has good effects.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] An array-type millimeter-wave terahertz near-field imaging device based on modulation and demodulation includes three signal sources, a data processing unit, a sample, an XYZ scanning stage, a millimeter-wave source and detection module, a mixer M1, a probe array composed of N probes, N Z-direction scanners, and N phase-locked demodulators Dn; wherein n=1, 2, ..., N;

[0007] The three signal sources are respectively a first signal source, a second signal source and a third signal source;

[0008] A first signal source is configured to drive a probe array consisting of N probes to vibrate in a Z direction;

[0009] An XY scanning stage is configured to scan the sample in an XY direction to achieve XY scanning imaging;

[0010] A second signal source is configured to provide a radio frequency signal to the millimeter wave terahertz source module;

[0011] A third signal source is configured to provide a local oscillator signal for the millimeter wave terahertz source module;

[0012] The millimeter wave terahertz source module is configured to up-convert the radio frequency signal and the local oscillator signal to the millimeter wave terahertz band to become a millimeter wave terahertz test signal and a millimeter wave terahertz reference signal respectively;

[0013] A mixer M1 configured to mix a signal;

[0014] A data processing unit is configured to stitch the amplitude scanning image and the phase scanning image of the probe array composed of N probes;

[0015] The first signal source drives the probe array composed of N probes to vibrate in the Z direction; the first probe performs simple harmonic vibration at a frequency of f1, the second probe performs simple harmonic vibration at a frequency of f2, and the Nth probe performs simple harmonic vibration at a frequency of f N Perform simple harmonic vibration; for samples with large surface roughness, each probe is individually controlled in a closed loop through the Z-direction scanning stage of each probe to keep the distance between the probe and the sample at the set value; at the same time, the sample is scanned in the XY direction through the XY scanning stage to achieve XY direction scanning imaging;

[0016] The second signal source and the third signal source provide the millimeter wave terahertz source module with a radio frequency signal and a local oscillator signal, respectively. After the millimeter wave terahertz source module up-converts the radio frequency signal to the millimeter wave terahertz band, the local oscillator signal and the millimeter wave terahertz reference signal are respectively formed.

[0017] The millimeter wave terahertz test signal is separated into two paths after passing through the signal separation device in the millimeter wave source and detection module;

[0018] The millimeter wave terahertz reference signal is down-converted to a frequency of f IF The reference intermediate frequency signal;

[0019] Another millimeter wave terahertz wave is radiated into free space by the horn antenna and coupled with the near-field probe array. The near-field signal of each probe contains the probe-sample interaction information. The near-field signal is modulated at a different frequency by each probe and then scattered into free space. After down-conversion by the millimeter wave terahertz detection module, the frequency component f is obtained. IF +f1+f2+…+f N The test intermediate frequency signal;

[0020] Test the intermediate frequency signal with frequency f IF The reference intermediate frequency signal is mixed twice by mixer M1 to obtain a frequency component f1+f2+…+f N The test signal;

[0021] The test signal is conditioned and transmitted to N phase-locked demodulators. The first phase-locked demodulator D1 uses the signal with a frequency of f1 provided by the first signal source as a reference signal and extracts the frequency components f1+f2+…+f N The signal with frequency f1 in the test intermediate frequency signal is used to realize the millimeter wave terahertz near-field imaging of the first probe channel; the second phase-locked demodulator D2 uses the signal with frequency f2 provided by the first signal source as the reference signal to extract the frequency components f1+f2+…+f N The signal component with frequency f2 in the test intermediate frequency signal is used to realize the millimeter wave terahertz near-field imaging of the second probe channel; the Nth phase-locked demodulator DN uses the f provided by the first signal source as the N The signal is used as a reference signal to extract the frequency components f1+f2+f N The frequency of the test intermediate frequency signal is f N signal components to realize millimeter-wave terahertz near-field imaging of the N-channel probe; the data processing unit splices the amplitude scanning image and the phase scanning image of the probe array composed of N probes to obtain the millimeter-wave terahertz near-field imaging of the sample to be tested.

[0022] In addition, the present invention also mentions a modulation and demodulation-based array millimeter-wave terahertz near-field imaging method, which adopts the modulation and demodulation-based array millimeter-wave terahertz near-field imaging device as described above, and specifically includes the following steps:

[0023] Step 1: The first signal source drives the probe array consisting of N probes to vibrate in the Z direction; the first probe performs simple harmonic vibration at frequency f1, the second probe performs simple harmonic vibration at frequency f2, and the Nth probe performs simple harmonic vibration at frequency f N Perform simple harmonic vibration; for samples with large surface roughness, each probe is individually controlled in a closed loop through the Z-direction scanning stage of each probe to keep the distance between the probe and the sample at the set value; at the same time, the sample is scanned in the XY direction through the XY scanning stage to achieve XY direction scanning imaging;

[0024] Step 2: The second signal source and the third signal source provide the millimeter wave terahertz source module with a radio frequency signal and a local oscillator signal, respectively. After the millimeter wave terahertz source module up-converts the radio frequency signal to the millimeter wave terahertz band, the local oscillator signal and the millimeter wave terahertz reference signal are respectively formed.

[0025] Step 3: The millimeter wave terahertz test signal is separated into two paths after passing through the signal separation device in the millimeter wave source and detection module; one path is down-converted with the millimeter wave terahertz reference signal to become a frequency of f IFThe other millimeter wave terahertz wave is radiated into free space by the horn antenna and coupled with the near-field probe array. The near-field signal of each probe contains the probe-sample interaction information. The near-field signal is modulated by each probe at a different frequency and then scattered into free space. After down-conversion by the millimeter wave terahertz detection module, a frequency component f is obtained. IF +f1+f2+…+f N The test intermediate frequency signal;

[0026] Step 4: Test the intermediate frequency signal with frequency f IF The reference intermediate frequency signal is mixed twice by mixer M1 to obtain a frequency component f1+f2+…+f N The test signal;

[0027] Step 5: The test signal is conditioned and transmitted to N phase-locked demodulators. The first phase-locked demodulator D1 uses the signal with a frequency of f1 provided by the first signal source as a reference signal and extracts the frequency components f1+f2+…+f N The signal with frequency f1 in the test intermediate frequency signal is used to realize the millimeter wave terahertz near-field imaging of the first probe channel; the second phase-locked demodulator D2 uses the signal with frequency f2 provided by the first signal source as the reference signal to extract the frequency components f1+f2+…+f N The signal component with frequency f2 in the test intermediate frequency signal is used to realize the millimeter wave terahertz near-field imaging of the second probe channel; the Nth phase-locked demodulator DN uses the f provided by the first signal source as the N The signal is used as a reference signal to extract the frequency components f1+f2+f N The frequency of the test intermediate frequency signal is f N The signal component of the probe is realized by the millimeter-wave terahertz near-field imaging of the N-channel.

[0028] Step 6: The data processing unit splices the amplitude scanning image and the phase scanning image of the probe array composed of N probes, thereby obtaining the millimeter-wave terahertz near-field imaging of the sample to be tested.

[0029] Beneficial technical effects brought by the present invention:

[0030] The modulation and demodulation-based array millimeter-wave terahertz near-field imaging technology proposed in the present invention adopts a probe array to expand the scanning imaging range and speed, and adopts a different excitation frequency for each probe to realize the modulation and demodulation of the millimeter-wave terahertz wave, which can realize the terahertz near-field imaging of N probes at the same time, thereby improving the near-field imaging scanning speed and scanning range. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1This is the schematic diagram of the array millimeter-wave terahertz near-field imaging device based on modulation and demodulation. DETAILED DESCRIPTION

[0032] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0033] The present invention provides an array-type millimeter-wave terahertz near-field imaging technology based on modulation and demodulation, wherein N near-field probes are used to scan the sample surface, and an N-channel phase-locked demodulator is used to realize simultaneous phase-locked demodulation of N terahertz near-field probe signals.

[0034] Figure 1 The principle of an array millimeter-wave terahertz near-field imaging device based on modulation and demodulation is given. Its basic components include: a first signal source, a first Z-direction scanner, a first probe, a second Z-direction scanner, a second probe, a third Z-direction scanner, a third probe, a sample, an XYZ scanning stage, a second signal source, a third signal source, a millimeter-wave source and detection module, a mixer M1, a first phase-locked demodulator D1, a second phase-locked demodulator D2, an Nth phase-locked demodulator DN, a data processing unit, etc.

[0035] The working principle of the invention is as follows:

[0036] The first signal source drives the probe array composed of N probes to vibrate in the Z direction, where the first probe performs simple harmonic vibration at frequency f1, the second probe performs simple harmonic vibration at frequency f2, and the Nth probe performs simple harmonic vibration at frequency f N Perform simple harmonic vibration; for samples with large surface roughness, each probe is individually controlled by the Z-axis scanning stage to close the probe-sample distance, so that the distance between the probe and the sample is always kept at the set value. At the same time, the sample is scanned in the XY direction by the XY scanning stage to achieve XY direction scanning imaging.

[0037] The second signal source and the second signal source provide the millimeter wave terahertz source module with RF signal and local oscillator signal respectively. After the millimeter wave terahertz source module up-converts them to the millimeter wave terahertz band, they become the millimeter wave terahertz test signal and the millimeter wave terahertz reference signal respectively. The millimeter wave terahertz test signal is separated into two paths after the signal separation device, and one path is down-converted with the millimeter wave terahertz reference signal to become a frequency of f IF The reference intermediate frequency signal is a millimeter wave terahertz wave, and the other millimeter wave terahertz wave is radiated into free space by the horn antenna and coupled with the near-field probe array. The near-field signal of each probe contains the probe-sample interaction information. The near-field signal is transmitted by each probe at different frequencies (f1, f2, ..., f N ) modulation, and then scattered into free space, and after down-conversion by the millimeter wave terahertz detection module, the frequency component f IF +f1+f2+…+f NThe test intermediate frequency signal is the same as the test intermediate frequency signal with a frequency of f IF After the reference intermediate frequency signal is mixed twice, the frequency components f1+f2+…+f N The test signal is conditioned and transmitted to the N-channel phase-locked demodulator. The phase-locked demodulator D1 uses the signal with frequency f1 provided by the probe signal source as the reference signal and extracts the frequency components f1+f2+…+f N The signal with frequency f1 in the test intermediate frequency signal can realize the millimeter wave terahertz near-field imaging of the first probe channel; the phase-locked demodulator D2 uses the signal with frequency f2 provided by the probe signal source as the reference signal to extract the frequency components f1+f2+…+f N The signal component with frequency f2 in the test intermediate frequency signal can realize the millimeter wave terahertz near-field imaging of the second probe channel; the phase-locked demodulator DN uses the f2 provided by the probe signal source to generate a signal component with frequency f2. N The signal is used as a reference signal to extract the frequency components f1+f2+f N The frequency of the test intermediate frequency signal is f N The signal components of the probe can realize millimeter-wave terahertz near-field imaging of the N-channel.

[0038] By splicing the amplitude scanning images and phase scanning images of N probes, the millimeter wave terahertz near-field imaging of the sample to be tested can be obtained. Compared with single-probe scanning imaging, array probe scanning imaging improves the scanning speed and imaging range.

[0039] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. An array-type millimeter-wave terahertz near-field imaging device based on modulation and demodulation, characterized in that: It includes three signal sources, a data processing unit, a sample, an XYZ scanning stage, a millimeter wave source and detection module, a mixer M1, a probe array consisting of N probes, N Z-direction scanners, and N phase-locked demodulators Dn; wherein n=1, 2, ..., N; The three signal sources are respectively a first signal source, a second signal source and a third signal source; A first signal source is configured to drive a probe array consisting of N probes to vibrate in a Z direction; An XY scanning stage is configured to scan the sample in an XY direction to achieve XY scanning imaging; A second signal source is configured to provide a radio frequency signal to the millimeter wave terahertz source module; A third signal source is configured to provide a local oscillator signal for the millimeter wave terahertz source module; The millimeter wave terahertz source module is configured to up-convert the radio frequency signal and the local oscillator signal to the millimeter wave terahertz band to become a millimeter wave terahertz test signal and a millimeter wave terahertz reference signal respectively; A mixer M1 configured to mix a signal; A data processing unit is configured to stitch the amplitude scanning image and the phase scanning image of the probe array composed of N probes; The first signal source drives the probe array composed of N probes to vibrate in the Z direction; the first probe performs simple harmonic vibration at a frequency of f1, the second probe performs simple harmonic vibration at a frequency of f2, and the Nth probe performs simple harmonic vibration at a frequency of f N Perform simple harmonic vibration; for samples with large surface roughness, each probe is individually controlled in a closed loop through the Z-direction scanning stage of each probe to keep the distance between the probe and the sample at the set value; at the same time, the sample is scanned in the XY direction through the XY scanning stage to achieve XY direction scanning imaging; The second signal source and the third signal source provide the millimeter wave terahertz source module with a radio frequency signal and a local oscillator signal, respectively. After the millimeter wave terahertz source module up-converts the radio frequency signal to the millimeter wave terahertz band, the local oscillator signal and the millimeter wave terahertz reference signal are respectively formed. The millimeter wave terahertz test signal is separated into two paths after passing through the signal separation device in the millimeter wave source and detection module; The millimeter wave terahertz reference signal is down-converted to a frequency of f IF The reference intermediate frequency signal; Another millimeter wave terahertz wave is radiated into free space by the horn antenna and coupled with the near-field probe array. The near-field signal of each probe contains the probe-sample interaction information. The near-field signal is modulated at a different frequency by each probe and then scattered into free space. After down-conversion by the millimeter wave terahertz detection module, the frequency component f is obtained. IF +f1+f2+…+f N The test intermediate frequency signal; Test the intermediate frequency signal with frequency f IF The reference intermediate frequency signal is mixed twice by mixer M1 to obtain a frequency component f1+f2+…+f N The test signal; The test signal is conditioned and transmitted to N phase-locked demodulators. The first phase-locked demodulator D1 uses the signal with a frequency of f1 provided by the first signal source as a reference signal and extracts the frequency components f1+f2+…+f N The signal with frequency f1 in the test intermediate frequency signal is used to realize the millimeter wave terahertz near-field imaging of the first probe channel; the second phase-locked demodulator D2 uses the signal with frequency f2 provided by the first signal source as the reference signal to extract the frequency components f1+f2+…+f N The signal component with frequency f2 in the test intermediate frequency signal is used to realize the millimeter wave terahertz near-field imaging of the second probe channel; the Nth phase-locked demodulator DN uses the f provided by the first signal source as the N The signal is used as a reference signal to extract the frequency components f1+f2+f N The frequency of the test intermediate frequency signal is f N signal components to realize millimeter-wave terahertz near-field imaging of the N-channel probe; the data processing unit splices the amplitude scanning image and the phase scanning image of the probe array composed of N probes to obtain the millimeter-wave terahertz near-field imaging of the sample to be tested.

2. An array-type millimeter-wave terahertz near-field imaging method based on modulation and demodulation, characterized in that: The array-type millimeter-wave terahertz near-field imaging device based on modulation and demodulation as claimed in claim 1 specifically comprises the following steps: Step 1: The first signal source drives the probe array consisting of N probes to vibrate in the Z direction; the first probe performs simple harmonic vibration at frequency f1, the second probe performs simple harmonic vibration at frequency f2, and the Nth probe performs simple harmonic vibration at frequency f N Perform simple harmonic oscillation; For samples with large surface roughness, the Z-axis scanning stage of each probe is used to perform closed-loop control on the probe-sample distance of each probe, so that the distance between the probe and the sample is always kept at the set value; at the same time, the sample is scanned in the XY direction through the XY scanning stage to achieve XY direction scanning imaging; Step 2: The second signal source and the third signal source provide the millimeter wave terahertz source module with a radio frequency signal and a local oscillator signal, respectively. After the millimeter wave terahertz source module up-converts the radio frequency signal to the millimeter wave terahertz band, the local oscillator signal and the millimeter wave terahertz reference signal are respectively formed. Step 3: The millimeter wave terahertz test signal is separated into two paths after passing through the signal separation device in the millimeter wave source and detection module; one path is down-converted with the millimeter wave terahertz reference signal to become a frequency of f IF The other millimeter wave terahertz wave is radiated into free space by the horn antenna and coupled with the near-field probe array. The near-field signal of each probe contains the probe-sample interaction information. The near-field signal is modulated by each probe at a different frequency and then scattered into free space. After down-conversion by the millimeter wave terahertz detection module, a frequency component f is obtained. IF +f1+f2+…+f N The test intermediate frequency signal; Step 4: Test the intermediate frequency signal with frequency f IF The reference intermediate frequency signal is mixed twice by mixer M1 to obtain a frequency component f1+f2+…+f N The test signal; Step 5: The test signal is conditioned and transmitted to N phase-locked demodulators. The first phase-locked demodulator D1 uses the signal with a frequency of f1 provided by the first signal source as a reference signal and extracts the frequency components f1+f2+…+f N The signal with frequency f1 in the test intermediate frequency signal is used to realize the millimeter wave terahertz near-field imaging of the first probe channel; the second phase-locked demodulator D2 uses the signal with frequency f2 provided by the first signal source as the reference signal to extract the frequency components f1+f2+…+f N The signal component with frequency f2 in the test intermediate frequency signal is used to realize the millimeter wave terahertz near-field imaging of the second probe channel; the Nth phase-locked demodulator DN uses the f provided by the first signal source as the N The signal is used as a reference signal to extract the frequency components f1+f2+f N The frequency of the test intermediate frequency signal is f N The signal component of the probe is realized by the millimeter-wave terahertz near-field imaging of the N-channel. Step 6: The data processing unit splices the amplitude scanning image and the phase scanning image of the probe array composed of N probes, thereby obtaining the millimeter-wave terahertz near-field imaging of the sample to be tested.

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