Portable terahertz thickness measuring system

Abstract

The invention discloses a portable terahertz time-domain spectroscopy system which comprises a portable host and a handheld probe, and the portable host and the handheld probe are connected through a cable. Wherein the portable host comprises a bias voltage source, a laser, a light path delayer, a signal acquisition system, a main control system, a display screen and a power supply system, and the handheld probe comprises a transmitting antenna, a detection antenna, a first off-axis parabolic mirror, a second off-axis parabolic mirror, a third off-axis parabolic mirror, a fourth off-axis parabolic mirror and a shell. Detection of an outdoor sample to be detected is realized, and random switching and use of equipment under different working conditions can be met.

Description

Technical Field

[0001] This invention belongs to the field of terahertz spectroscopy and imaging technology, specifically relating to a portable terahertz thickness measurement system. Background Technology

[0002] Terahertz waves are electromagnetic waves with strong penetrating power and low photon energy, with frequencies ranging from 0.1 to 10 THz (1 THz = 10 THz). 12 Terahertz spectroscopy and imaging systems utilize terahertz waves for photoconductive sampling and are widely used in material identification, security inspection, non-destructive testing of materials and structures, thickness measurement of metal surface coatings, in vivo examination of biological tissues, and wireless communication.

[0003] like Figure 1 As shown, an existing terahertz time-domain spectroscopy system includes a bias source, a laser, an optical delayer, a transmitting antenna, a detecting antenna, a signal acquisition system, a main control system, and a display screen. The laser outputs two in-phase, co-frequency femtosecond pulses. One femtosecond pulse (pump light) is output to the transmitting antenna, while the other femtosecond pulse (detector light) is delayed by an optical fiber delayer before reaching the detector antenna. The femtosecond pulses excite photogenerated carriers within the photoconductive material. Under the influence of an external bias source, these carriers rapidly migrate and radiate high-repetition-frequency pulsed terahertz waves into space. These pulsed terahertz waves propagate to the detector antenna, where they meet the femtosecond pulses (detector light), generating a current. The signal acquisition system samples this current to determine the terahertz signal intensity. Based on this terahertz signal intensity, material identification and thickness measurement are achieved. Traditional terahertz systems involve numerous components, complex power supply, and relatively high requirements for the optical path. Therefore, most current terahertz systems are indoor devices and cannot measure the coating thickness of outdoor equipment (such as automotive paint, aircraft coatings, etc.). To address this, this invention presents a portable terahertz thickness measurement system. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and to design a portable terahertz thickness measurement system.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] This invention relates to a portable terahertz time-domain spectroscopy system, comprising a portable main unit and a handheld probe, which are connected by cables including a power cable, a control cable, and a communication cable. The portable main unit includes a bias source, a laser, an optical path delay unit, a signal acquisition system, a main control system, a display screen, and a power supply system. The handheld probe includes a transmitting antenna, a detecting antenna, a first off-axis parabolic mirror, a second off-axis parabolic mirror, a third off-axis parabolic mirror, a fourth off-axis parabolic mirror, and a housing. The second and third off-axis parabolic mirrors are fixed to the top of the housing's inner cavity, and the first and fourth off-axis parabolic mirrors are fixed to the bottom of the housing's inner cavity. The transmitting and detecting antennas are fixed to the rear side of the housing's inner cavity. A light-transmitting hole communicating with the inner cavity is opened at the front of the housing, serving as a detection port. During use, the detection port is directly aligned with the sample to be tested. The laser outputs two in-phase femtosecond pulses, one of which is output to the transmitting antenna. The transmitting antenna and... A bias source is connected, generating a terahertz signal under the electric field. The terahertz signal is collimated by a first off-axis parabolic mirror and incident on a second off-axis parabolic mirror. After being focused by the second off-axis parabolic mirror, it passes through a light aperture and hits the sample under test. The reflected light from the sample passes through the light aperture and is incident on a third off-axis parabolic mirror, then collimated and enters a fourth off-axis parabolic mirror. After being focused, it reaches the terahertz detection antenna. Another femtosecond pulse light is delayed by an optical fiber delayer before reaching the detection antenna. The terahertz signal and the femtosecond pulse light meet at the detection antenna, generating a current. The signal acquisition system is connected to the detection antenna and samples the current to obtain the terahertz signal intensity, which is then sent to the main control system for processing. The display screen is used to display the information processed by the main control system. The main control system is connected to the bias source, laser, optical delayer, signal acquisition system, and display screen to control the operation of related components. The power supply system is connected to the main control system to provide power to the portable terahertz time-domain spectroscopy system.

[0007] Specifically, a fixing part is provided inside the outer shell. The fixing part is a cuboid cavity structure. The transmitting antenna and the detecting antenna arranged horizontally side by side are fixed on the rear side of the cavity inside the fixing part. The second off-axis parabolic mirror and the third off-axis parabolic mirror are fixed on the top of the cavity inside the fixing part. The first off-axis parabolic mirror and the fourth off-axis parabolic mirror are fixed on the bottom of the cavity inside the fixing part. The transmitting antenna, the first off-axis parabolic mirror and the second off-axis parabolic mirror are in the same optical path. The detecting antenna, the third off-axis parabolic mirror and the fourth off-axis parabolic mirror are in the same optical path. The two optical paths are parallel.

[0008] A handhold is formed on one side of the outer shell for easy gripping.

[0009] Preferably, a display screen is provided on one side of the handheld probe to display the test results, and trigger and save function buttons are provided on the handheld part.

[0010] Specifically, the power supply system includes a first reverse connection protection circuit, an internal power supply system, a Boost circuit, a charging circuit, a rechargeable battery, a discharging circuit, and a second reverse connection protection circuit. An external power source is connected to the internal power supply system through the first reverse connection protection circuit to directly supply power to the internal power supply system. The external power source is connected to the rechargeable battery through the Boost circuit and the charging circuit to charge the rechargeable battery. The rechargeable battery is connected to the internal power supply system through the discharging circuit and the second reverse connection protection circuit to supply power to the internal power supply system.

[0011] Compared with the prior art, the present invention has the following advantages: (1) The handheld probe design enables the detection of outdoor samples, and the operation is convenient during the detection process; (2) The power supply system design can meet the needs of the equipment to switch between different working conditions at will. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the structure of an existing portable terahertz time-domain spectroscopy system.

[0013] Figure 2 This is a schematic diagram of the handheld probe structure in Example 1.

[0014] Figure 3 This is a schematic diagram of the internal structure of the handheld probe in Example 1.

[0015] Figure 4 This is a schematic diagram of the internal optical path of the handheld probe in Example 1.

[0016] Figure 5 This is a schematic diagram of the power supply system structure involved in Example 1. Detailed Implementation

[0017] The present invention will be further described below through specific embodiments and in conjunction with the accompanying drawings.

[0018] Example 1

[0019] like Figure 1-4As shown, a portable terahertz time-domain spectroscopy system includes a portable main unit and a handheld probe, which are connected by cables including power cables, control cables, and communication cables (e.g., optical fibers). The portable main unit includes a bias source, a laser, an optical path delay unit, a signal acquisition system, a main control system, a display screen, and a power supply system. The handheld probe includes a transmitting antenna 1, a detecting antenna 2, a first off-axis parabolic mirror 3, a second off-axis parabolic mirror 4, a third off-axis parabolic mirror 5, a fourth off-axis parabolic mirror 6, and a housing 7. The second off-axis parabolic mirror 4 and the third off-axis parabolic mirror 5 are fixed to the top of the inner cavity of the housing, and the first off-axis parabolic mirror 3 and the fourth off-axis parabolic mirror 6 are fixed to the bottom of the inner cavity of the housing. The transmitting antenna 1 and the detecting antenna 2 are fixed to the rear side of the inner cavity of the housing. A light-transmitting hole communicating with the inner cavity of the housing is opened at the front end of the housing, which serves as the detection port. During use, the detection port is directly aligned with the sample to be tested. The laser is used to output two femtosecond pulses of the same frequency and phase. One of the femtosecond pulses (pump light) is output to the transmitting antenna 1, which is connected to the bias source. A terahertz signal is generated under the influence of the electric field produced by the bias source. This terahertz signal is collimated by the first off-axis parabolic mirror 3 and incident on the second off-axis parabolic mirror 4. After being focused by the second off-axis parabolic mirror 4, it passes through a light aperture and strikes the sample under test. The reflected light from the sample passes through a light aperture 8 and is incident on the third off-axis parabolic mirror 5. It is then collimated and enters the fourth off-axis parabolic mirror 6, where it is focused and reaches the terahertz detection antenna 7. Another femtosecond pulse (detection light) is delayed by an optical fiber delayer before reaching the detection antenna 2. The terahertz signal and the femtosecond pulse... When the probe light meets the probe antenna 2, it generates a current. The signal acquisition system is connected to the probe antenna 2 and samples the current to obtain the terahertz signal intensity, which is then sent to the main control system for processing (e.g., restoring the original signal and calculating the sample thickness). The display screen is used to display the information processed by the main control system. The main control system is connected to the bias source, laser, optical path delayer, signal acquisition system, and display screen to control the operation of related components. The power supply system is connected to the main control system to provide power to the portable terahertz time-domain spectroscopy system.

[0020] Specifically, in this embodiment, a fixing part 701 is provided inside the outer shell 7. The fixing part 701 is a rectangular cavity structure. The transmitting antenna 1 and the detecting antenna 2, which are arranged side by side in the horizontal direction, are fixed on the rear side of the cavity inside the fixing part 701. The second off-axis parabolic mirror 4 and the third off-axis parabolic mirror 5 are fixed on the top of the cavity inside the fixing part 701. The first off-axis parabolic mirror 3 and the fourth off-axis parabolic mirror 6 are fixed on the bottom of the cavity inside the fixing part 701. The transmitting antenna 1, the first off-axis parabolic mirror 3 and the second off-axis parabolic mirror 4 are in the same optical path (transmitting optical path), and the detecting antenna 2, the third off-axis parabolic mirror 5 and the fourth off-axis parabolic mirror 6 are in the same optical path (detecting optical path). The two optical paths are parallel.

[0021] In this embodiment, a handhold 702 is formed on one side of the outer shell 7 for easy gripping.

[0022] Specifically, the handheld probe adopts a fully airtight design to improve the equipment's environmental adaptability.

[0023] Preferably, a display screen is provided on one side of the handheld probe to display the test results, and trigger and save function buttons are provided on the handheld part for convenient operation during the test.

[0024] Specifically, such as Figure 5 As shown, the power supply system involved in this embodiment includes a first reverse connection protection circuit 10, an internal power supply system 11, a Boost circuit 12, a charging circuit 13, a rechargeable battery 14, a discharging circuit 15, and a second reverse connection protection circuit 16. An external power supply 9 is connected to the internal power supply system 11 through the first reverse connection protection circuit 10 to directly supply power to the internal power supply system 11. The external power supply 9 is connected to the rechargeable battery 14 through the Boost circuit 12 and the charging circuit 13 in sequence to charge the rechargeable battery 14. The rechargeable battery 14 is connected to the internal power supply system 11 through the discharging circuit 15 and the second reverse connection protection circuit 16 in sequence to supply power to the internal power supply system.

[0025] Specifically, the maximum power supply voltage for all components in the entire system is 24V, so the external power supply voltage is selected as 24V, the internal power supply system power supply is 24V, and the rechargeable battery is selected with a voltage of 24V. The theoretical maximum voltage after full charge is 25.2V, which is greater than the external 24V. A BOOST circuit is designed before the charging circuit to boost the voltage to approximately 27V.

Claims

1. A portable terahertz time-domain spectroscopic system, characterized in that, The system includes a portable main unit and a handheld probe, which are connected by a cable. The portable main unit includes a bias source, a laser, an optical delay unit, a signal acquisition system, a main control system, a display screen, and a power supply system. The handheld probe includes a transmitting antenna, a detecting antenna, a first off-axis parabolic mirror, a second off-axis parabolic mirror, a third off-axis parabolic mirror, a fourth off-axis parabolic mirror, and a housing. The second and third off-axis parabolic mirrors are fixed to the top of the housing's inner cavity, the first and fourth off-axis parabolic mirrors are fixed to the bottom of the housing's inner cavity, the transmitting antenna and the detecting antenna are fixed to the rear side of the housing's inner cavity, and a light-transmitting hole is opened at the front of the housing, communicating with the inner cavity. The detection port is directly aligned with the sample under test. The laser outputs two femtosecond pulses of the same frequency and phase. One femtosecond pulse is output to the transmitting antenna, which is connected to a bias source. Under the electric field generated by the bias source, a terahertz signal is generated. The terahertz signal is collimated by the first off-axis parabolic mirror and incident on the second off-axis parabolic mirror. After being focused by the second off-axis parabolic mirror, it passes through the light aperture and hits the sample under test. The light reflected from the sample passes through the light aperture and is incident on the third off-axis parabolic mirror. Then it is collimated and enters the fourth off-axis parabolic mirror, and after being focused, it reaches the terahertz detection antenna. The other femtosecond pulse is delayed by an optical fiber delayer before reaching the detection antenna.

2. The portable terahertz time-domain spectroscopic system according to claim 1, characterized in that, The housing is equipped with a fixing part, which is a rectangular cavity structure. The transmitting antenna and the detecting antenna, which are arranged horizontally side by side, are fixed to the rear side of the cavity of the fixing part. The second off-axis parabolic mirror and the third off-axis parabolic mirror are fixed to the top of the cavity of the fixing part, and the first off-axis parabolic mirror and the fourth off-axis parabolic mirror are fixed to the bottom of the cavity of the fixing part. The transmitting antenna, the first off-axis parabolic mirror and the second off-axis parabolic mirror are in the same optical path, and the detecting antenna, the third off-axis parabolic mirror and the fourth off-axis parabolic mirror are in the same optical path. The two optical paths are parallel.

3. The portable terahertz time-domain spectroscopic system according to claim 1, characterized in that, A handhold is formed on one side of the outer casing.

4. The portable terahertz time-domain spectroscopic system according to claim 3, characterized in that, A display screen is set on one side of the handheld probe to display the test results, and trigger and save function buttons are set on the handheld part.

5. The portable terahertz time-domain spectroscopic system according to claim 1, characterized in that, The power supply system includes a first reverse connection protection circuit, an internal power supply system, a Boost circuit, a charging circuit, a rechargeable battery, a discharging circuit, and a second reverse connection protection circuit. An external power source is connected to the internal power supply system through the first reverse connection protection circuit to directly supply power to the internal power supply system. The external power source is connected to the rechargeable battery through the Boost circuit and the charging circuit to charge the rechargeable battery. The rechargeable battery is connected to the internal power supply system through the discharging circuit and the second reverse connection protection circuit to supply power to the internal power supply system.

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