Time-Resolved Second-Harmonic Generation Measurement System and Measurement Method on an Ultrafast Time Scale

Abstract

The present invention relates to the technical field of optical scientific research instruments, and provides a time-resolved second harmonic measurement system and a measurement method on an ultrafast time scale. The measurement system includes: a femtosecond laser light source module, a probe light delay module, a sample chamber module, an excitation light chopping module, a detection module, and a system control module; the femtosecond laser light source module includes: a femtosecond laser, a beam splitting flat mirror, and an optical parametric amplifier; after the laser emitted by the femtosecond laser passes through the beam splitting flat mirror, a part of the light is used as the probe light and is directed to the first reflector, and the other part of the light is distributed to the optical parametric amplifier. The optical parametric amplifier generates continuously tunable laser light, which is used as the excitation light and is directed to the excitation light chopping module; the probe light is emitted after multiple reflections inside the probe light delay module. The present invention can perform time-resolved second harmonic measurement on organic thin films and devices on an ultrafast time scale.

Description

Technical Field

[0001] The present invention relates to the technical field of optical scientific research instruments, and particularly relates to a time-resolved second harmonic generation measurement system and measurement method on an ultrafast time scale. Background Art

[0002] The charge carrier mobility of organic materials is one of the important characteristics in optoelectronics. In recent years, scientific research has confirmed that the traditional mobility, usually assumed to be a time constant, may not be sufficient to fully describe the charge transport on organic devices. Therefore, from a fundamental perspective, researchers have shifted their focus to studying whether the charge transport on an ultrafast time scale is restricted by the same processes as macroscopic transport, that is, restricted by energy, geometric disorder, and trapping.

[0003] The technique of electric field-induced second harmonic generation can induce the generation of second harmonics with different properties by changing the electric field in which the sample (organic thin film or device, such as indium gallium arsenide, etc., hereinafter collectively referred to as the sample) is located, and then analyzing this second harmonic can obtain the corresponding charge carrier mobility.

[0004] In the traditional second harmonic generation research device, the way to generate the second harmonic is to use a laser beam to irradiate the sample, and then a frequency-doubled light beam is generated (for example, a laser beam with a wavelength of 1030 nm irradiates the sample, and a light beam with a wavelength of 515 nm is generated), which is the second harmonic. However, this second harmonic is not measured using the pump-probe technique. It is a steady-state, single-moment second harmonic without time regulation of the laser, so it does not have the characteristic of time resolution; at the same time, no electric field is applied to the sample, so the charge carrier mobility of the sample cannot be studied. Summary of the Invention

[0005] The present invention mainly solves the technical problem that the traditional second harmonic generation device cannot measure the time-resolved second harmonic and thus cannot study the charge carrier mobility of the sample because it does not perform time regulation on the laser and does not change the electric field in which the sample is located. The present invention proposes a time-resolved second harmonic generation measurement system and measurement method on an ultrafast time scale, which uses an optical delay line to perform time regulation on the laser and applies a pulsed voltage to the sample with a pulsed power supply, and can perform time-resolved second harmonic generation measurement on organic thin films and devices on an ultrafast time scale.

[0006] The present invention provides a time-resolved second harmonic generation measurement system on an ultrafast time scale, including: a femtosecond laser light source module, a probe light delay module, a sample chamber module, an excitation light chopping module, a detection module, and a system control module;

[0007] The femtosecond laser light source module includes: a femtosecond laser, a beam splitting flat plate, and an optical parametric amplifier;

[0008] After the laser emitted by the femtosecond laser passes through the beam splitter flat mirror, part of the light is used as the probe light and is directed towards the first mirror, and the other part of the light is distributed to the optical parametric amplifier. The optical parametric amplifier generates continuously tunable laser light, which is used as the excitation light and is directed towards the excitation light chopping module;

[0009] The first mirror injects the probe light into the probe light delay module, and the probe light is emitted after multiple reflections inside the probe light delay module; the probe light delay module is used to change the optical path of the probe light, thereby changing the time difference between the probe light and the excitation light reaching the sample;

[0010] The sample chamber module includes: a first plano-convex lens, a sample, a second plano-convex lens, and a pulse power supply;

[0011] After the probe light is emitted from the probe light delay module, it is reflected by the second mirror and enters the sample chamber module through the first attenuator; the probe light is focused on the sample through the first plano-convex lens, and then becomes parallel light through the second plano-convex lens; the sample is connected to the pulse power supply, and a pulsed voltage is applied to the sample through the pulse power supply;

[0012] The excitation light chopping module includes: an optical chopper, a second attenuator, and a third plano-convex lens;

[0013] The optical chopper controls the passage or non-passage of the excitation light, presenting two forms of having excitation light and no excitation light on the sample; the excitation light emitted by the optical parametric amplifier is chopped by the optical chopper, the intensity of the excitation light is adjusted by the second attenuator, and then it is focused and emitted after passing through the third plano-convex lens. During the focusing process, it is reflected by the third mirror and finally focused on the sample. The focusing position of the excitation light is the same as the focusing position of the probe light;

[0014] The detection module includes: a PMT photomultiplier tube, a high-voltage power supply, and a lock-in amplifier;

[0015] The PMT photomultiplier tube detects the probe light emitted from the sample chamber module; the PMT photomultiplier tube converts the optical signal into an electrical signal and inputs it into the lock-in amplifier; the PMT photomultiplier tube is connected to the high-voltage power supply, and the high-voltage power supply is used to apply a voltage to the PMT photomultiplier tube;

[0016] The system control module includes: a junction box and a computer. The junction box simultaneously transmits the synchronization signal of the femtosecond laser to the optical chopper and the pulse power supply, and can trigger the optical chopper and the pulse power supply to work; the computer is respectively connected to the femtosecond laser light source module, the probe light delay module, the junction box, and the lock-in amplifier in terms of signals.

[0017] Preferably, the femtosecond laser emits laser light with a wavelength of 800 nm or 1030 nm.

[0018] Preferably, the optical parametric amplifier generates continuously tunable laser light with a wavelength of 200 - 2000 nm.

[0019] Preferably, the probe light delay module includes: an electric displacement stage, a first delay module mirror, a second delay module mirror, a third delay module mirror, a fourth delay module mirror, a fifth delay module mirror, a sixth delay module mirror, and a hollow retroreflector;

[0020] The electric displacement stage is arranged at one end of the probe light delay module, and the six delay module mirrors are arranged at the other end of the probe light delay module;

[0021] The fifth delay module mirror and the sixth delay module mirror are arranged corresponding to each other; the first delay module mirror and the second delay module mirror are arranged behind the fifth delay module mirror; the third delay module mirror and the fourth delay module mirror are arranged behind the sixth delay module mirror; the second delay module mirror and the fourth delay module mirror are in corresponding positions;

[0022] And the first delay module mirror, the second delay module mirror, the third delay module mirror, the fourth delay module mirror, the fifth delay module mirror, and the sixth delay module mirror are respectively at an angle of 45° to the length direction of the probe light delay module.

[0023] Preferably, the junction box adopts a BNC - 2121 type junction box.

[0024] Correspondingly, the present invention also provides a measurement method for a time - resolved second - harmonic generation measurement system on an ultrafast time scale according to any embodiment of the present invention, including the following processes:

[0025] Step 100, connect all the devices of the time - resolved second - harmonic generation measurement system, and the high - voltage power supply applies voltage to the PMT photomultiplier tube;

[0026] Step 200, the computer controls the optical parametric amplifier in the femtosecond laser light source module to select the wavelength;

[0027] Step 300, the computer controls the femtosecond laser to turn on. At this time, the femtosecond laser transmits an electrical signal to the junction box, and the junction box distributes this electrical signal to the optical chopper and the pulse power supply simultaneously; at this time, the optical chopper chops the excitation light emitted by the optical parametric amplifier, and the output signal of the optical chopper is transmitted to the lock - in amplifier; the pulse power supply applies a pulsed voltage to the sample to change the electric field where the sample is located;

[0028] Step 400, the computer controls the movement of the probe light delay module, and the system starts scanning and data acquisition until the probe light delay module stops moving;

[0029] Step 500: The PMT photomultiplier converts the optical signal into an electrical signal and transmits it to the lock-in amplifier.

[0030] Step 600: The lock-in amplifier transmits the processed data to the computer to display the required data information.

[0031] Step 700: The detection light delay module stops moving, and the system stops data acquisition.

[0032] A time-resolved second harmonic generation measurement system and method on an ultrafast time scale provided by the present invention have the following advantages compared with the prior art:

[0033] 1. The use of a pump-probe technique consisting of a detection light and an excitation light, which is a commonly used and effective research method for kinetic studies of samples in the field of photochemistry.

[0034] 2. Utilizing an optical delay line to control the time of the detection light. By increasing the optical path of the detection light, the propagation time of the detection light is extended, and at the same time, the time difference between the detection light and the excitation light can be controlled, thereby measuring the second harmonic with time-resolved characteristics.

[0035] 3. Using a pulsed power supply, a pulsed voltage can be applied to the sample, and the voltage of the pulsed power supply is continuously adjustable, up to 20V. Thus, the electric field of the second harmonic can be changed, enabling experimental research on the carrier mobility of the sample and providing a reliable analysis basis for the scientific research of the sample.

[0036] 4. Combining with a femtosecond laser light source, the dynamics of the sample can be tested on an ultrafast time scale.

[0037] 5. Using a lock-in amplifier to process data, with fast processing speed, complete technology, and accurate and reliable data.

[0038] 6. Applying a high voltage to the PMT photomultiplier using a high-voltage power supply can greatly improve the detection sensitivity of the PMT photomultiplier. Description of the Drawings

[0039] Figure 1 It is a schematic composition diagram of the time-resolved second harmonic generation measurement system on an ultrafast time scale provided by the present invention.

[0040] Figure 2 It is a schematic diagram of the detection light delay module provided by the present invention.

[0041] Reference Numerals: I, femtosecond laser light source module; II, probe light delay module; III, sample chamber module; IV, excitation light chopping module; V, detection module; VI, system control module; 1, femtosecond laser; 2, beam splitter flat mirror; 3, optical parametric amplifier; 4, first reflector; 5, optical delay line; 6, second reflector; 7, first attenuator; 8, first plano-convex lens; 9, sample; 10, second plano-convex lens; 11, PMT photomultiplier tube; 12, optical chopper; 13, second attenuator; 14, third plano-convex lens; 15, third reflector; 16, high voltage power supply; 17, pulse power supply; 18, lock-in amplifier; 19, junction box; 20, computer; 201, first delay module reflector; 202, second delay module reflector; 203, third delay module reflector; 204, fourth delay module reflector; 205, fifth delay module reflector; 206, sixth delay module reflector; 207, motorized displacement stage; 208, hollow retroreflector. Detailed Implementation Modes

[0042] To make the technical problems solved by the present invention, the technical solutions adopted and the achieved technical effects clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present invention, rather than limiting the present invention. Additionally, it should be noted that for the sake of description, only parts related to the present invention are shown in the accompanying drawings rather than all the content.

[0043] Embodiment 1

[0044] As Figure 1 shown, the time-resolved second harmonic generation measurement system on an ultrafast time scale provided by the embodiment of the present invention includes: a femtosecond laser light source module I, a probe light delay module II, a sample chamber module III, an excitation light chopping module IV, a detection module V, and a system control module VI.

[0045] The femtosecond laser light source module I includes: a femtosecond laser 1, a beam splitter flat mirror 2, and an optical parametric amplifier 3; after the laser emitted by the femtosecond laser 1 passes through the beam splitter flat mirror 2, a part of the light is used as the probe light and is directed to the first reflector 4, and the other part of the light is fed to the optical parametric amplifier 3. The optical parametric amplifier 3 generates continuously tunable laser light, which is used as the excitation light and is directed to the excitation light chopping module IV. Among them, the femtosecond laser 1 emits laser light with a wavelength of 800 nm or 1030 nm. The optical parametric amplifier 3 generates continuously tunable laser light with a wavelength of 200 - 2000 nm.

[0046] The first mirror 4 injects the detection light into the detection light delay module II, and the detection light is emitted after multiple reflections inside the detection light delay module II; the detection light delay module II is used to change the optical path of the detection light, so as to change the time difference between the detection light and the excitation light reaching the sample 9.

[0047] As Figure 2 shown, the detection light delay module II adopts an optical delay line 5, including: an electric displacement stage 207, a first delay module mirror 201, a second delay module mirror 202, a third delay module mirror 203, a fourth delay module mirror 204, a fifth delay module mirror 205, a sixth delay module mirror 206, and a hollow retroreflector 208.

[0048] The electric displacement stage 207 is arranged at one end of the detection light delay module II, and the six delay module mirrors are arranged at the other end of the detection light delay module II; among them, the fifth delay module mirror 205 and the sixth delay module mirror 206 are arranged correspondingly; the first delay module mirror 201 and the second delay module mirror 202 are arranged behind the fifth delay module mirror 205; the third delay module mirror 203 and the fourth delay module mirror 204 are arranged behind the sixth delay module mirror 206; the second delay module mirror 202 and the fourth delay module mirror 204 are in corresponding positions. And the first delay module mirror 201, the second delay module mirror 202, the third delay module mirror 203, the fourth delay module mirror 204, the fifth delay module mirror 205, and the sixth delay module mirror 206 are respectively at an angle of 45° to the length direction of the detection light delay module II.

[0049] The detection light enters the optical delay line 5 through the first mirror 4, is emitted after several reflections inside, and the optical path of the detection light can be changed by moving the delay line, so as to change the time difference between the detection light and the excitation light reaching the sample 9.

[0050] The sample chamber module III includes: a first plano-convex lens 8, a sample 9, a second plano-convex lens 10, and a pulse power supply 17;

[0051] After the detection light is emitted from the detection light delay module II, it is reflected by the second mirror 6, enters the sample chamber module III through the first attenuator 7; the detection light is focused on the sample 9 through the first plano-convex lens 8, and then becomes parallel light through the second plano-convex lens 10; the sample 9 is connected to the pulse power supply 17, and a pulse voltage is applied to the sample 9 through the pulse power supply 17 (the pulse power supply is connected to the positive and negative electrodes of the sample 9, and the sample 9 has electrodes), so as to change the electric field where the sample 9 is located. The sample 9 is an organic thin film or a device. Specifically, the pulse power supply applies a pulse voltage not exceeding 20V to the sample 9, which is set in the form of a square wave signal with a duty cycle of 50%.

[0052] The excitation light chopping module IV includes an optical chopper 12, a second attenuator 13, and a third plano-convex lens 14. The optical chopper 12 controls the passage of the excitation light, presenting two forms of having excitation light (Pump) and no excitation light (Unpump) on the sample 9. The excitation light emitted by the optical parametric amplifier 3 is chopped by the optical chopper 12, the intensity of the excitation light is adjusted by the second attenuator 13, and then it is focused and emitted after passing through the third plano-convex lens 14. During the focusing process, it is reflected by the third mirror 15 and finally focused on the sample 9. The focusing position of the excitation light is the same as that of the detection light.

[0053] The detection module V includes a PMT photomultiplier tube 11, a high-voltage power supply 16, and a lock-in amplifier 18. The PMT photomultiplier tube 11 detects the detection light emitted from the sample chamber module III. The PMT photomultiplier tube 11 converts the optical signal into an electrical signal and inputs it into the lock-in amplifier 18 for data processing. The lock-in amplifier 18 transmits the processed data (intensity value) to the computer 20. At the same time, the optical delay line 5 feeds back the time information to the computer 20. The combination of the two gives the intensity values at different times, which is the time-resolved second harmonic. The PMT photomultiplier tube 11 is connected to the high-voltage power supply 16, and the high-voltage power supply 16 is used to apply a voltage to the PMT photomultiplier tube 11, which can improve the detection sensitivity of the PMT photomultiplier tube 11.

[0054] The system control module VI includes a junction box 19 and a computer 20. The junction box 19 simultaneously transmits the synchronization signal of the femtosecond laser 1 to the optical chopper 12 and the pulse power supply 17, and can trigger the optical chopper 12 and the pulse power supply 17 to work. The junction box 19 adopts a BNC-2121 type junction box. The computer 20 is respectively connected to the femtosecond laser light source module I, the detection light delay module II, the junction box 19, and the lock-in amplifier 18 by signals. The computer 20 can control the switch of the femtosecond laser light source module I, the movement of the detection light delay module II, the signal transmission of the junction box 19, and the data reception from the lock-in amplifier 18.

[0055] The measurement system of the present invention first generates the second harmonic, and then observes the change of the second harmonic by applying a pulsed voltage, which can be used to analyze the changes occurring inside the sample by analyzing the change of the second harmonic, such as analyzing the carrier mobility, etc., providing a reliable analysis basis for the scientific research of the sample.

[0056] Embodiment 2

[0057] This embodiment provides a measurement method for a time-resolved second harmonic measurement system on an ultrafast time scale according to any embodiment of the present invention, including the following processes:

[0058] Step 100: Connect all the devices of the second harmonic measurement system, turn on the power of all devices, and the high-voltage power supply 16 applies voltage to the PMT photomultiplier 11.

[0059] Step 200: The computer 20 controls the optical parametric amplifier 3 in the femtosecond laser light source module I to select the wavelength.

[0060] Step 300: The computer 20 controls the femtosecond laser 1 to turn on. At this time, the femtosecond laser 1 transmits an electrical signal to the junction box 19, and the junction box 19 distributes this electrical signal to the optical chopper 12 and the pulse power supply 17 simultaneously; at this time, the optical chopper 12 rotates to chop the excitation light emitted by the optical parametric amplifier 3, and the output signal of the optical chopper 12 is transmitted to the lock-in amplifier 18; the pulse power supply 17 applies a pulsed voltage to the sample 9 to change the electric field where the sample 9 is located.

[0061] Step 400: The computer 20 controls the probe light delay module II to move, and the system starts to scan and collect data until the probe light delay module II stops moving (the probe light delay module II can also be controlled to stop moving by the computer 20 during the process).

[0062] Step 500: The PMT photomultiplier 11 converts the optical signal into an electrical signal and transmits it to the lock-in amplifier 18.

[0063] Step 600: The lock-in amplifier 18 transmits the processed data to the computer 20 to display the required data information.

[0064] Step 700: The probe light delay module II stops moving, and the system stops data collection.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: modifying the technical solutions recorded in the foregoing embodiments, or equivalently replacing some or all of the technical features therein, does not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A time-resolved second harmonic generation measurement system on an ultrafast time scale, characterized in that, it includes: a femtosecond laser light source module (I), a probe light delay module (II), a sample chamber module (III), an excitation light chopping module (IV), a detection module (V) and a system control module (VI); The femtosecond laser light source module (I) includes: a femtosecond laser (1), a beam splitting flat mirror (2) and an optical parametric amplifier (3); After the laser emitted by the femtosecond laser (1) passes through the beam splitting flat mirror (2), a part of the light is used as the probe light and shoots towards the first reflecting mirror (4), and the other part of the light is distributed to the optical parametric amplifier (3). The optical parametric amplifier (3) generates continuously adjustable laser light, which is used as the excitation light and shoots towards the excitation light chopping module (IV); The first reflecting mirror (4) injects the probe light into the probe light delay module (II), and the probe light is emitted after multiple reflections inside the probe light delay module (II); the probe light delay module (II) is used to change the optical path of the probe light, thereby changing the time difference between the probe light and the excitation light reaching the sample (9); The probe light delay module (II) includes: a motorized displacement stage (207), a first delay module reflecting mirror (201), a second delay module reflecting mirror (202), a third delay module reflecting mirror (203), a fourth delay module reflecting mirror (204), a fifth delay module reflecting mirror (205), a sixth delay module reflecting mirror (206) and a hollow retroreflector (208); The motorized displacement stage (207) is arranged at one end of the probe light delay module (II), and the six delay module reflecting mirrors are arranged at the other end of the probe light delay module (II); The fifth delay module reflecting mirror (205) and the sixth delay module reflecting mirror (206) are arranged correspondingly; the first delay module reflecting mirror (201) and the second delay module reflecting mirror (202) are arranged behind the fifth delay module reflecting mirror (205); the third delay module reflecting mirror (203) and the fourth delay module reflecting mirror (204) are arranged behind the sixth delay module reflecting mirror (206); the second delay module reflecting mirror (202) corresponds to the position of the fourth delay module reflecting mirror (204); and the first delay module reflecting mirror (201), the second delay module reflecting mirror (202), the third delay module reflecting mirror (203), the fourth delay module reflecting mirror (204), the fifth delay module reflecting mirror (205), the sixth delay module reflecting mirror (206) are respectively at an angle of 45° with the length direction of the probe light delay module (II); The sample chamber module (III) includes: a first plano-convex lens (8), a sample (9), a second plano-convex lens (10) and a pulsed power supply (17); After the detection light is emitted from the detection light delay module (II), it is reflected by the second mirror (6) and enters the sample chamber module (III) through the first attenuator (7); the detection light is focused on the sample (9) through the first plano-convex lens (8), and then becomes parallel light through the second plano-convex lens (10); the sample (9) is connected to a pulse power supply (17), and a pulse voltage is applied to the sample (9) through the pulse power supply (17). The excitation light chopping module (IV) includes: an optical chopper (12), a second attenuator (13), and a third plano-convex lens (14). The optical chopper (12) controls the passage of the excitation light, presenting two forms of having excitation light and no excitation light on the sample (9); the excitation light emitted from the optical parametric amplifier (3) is chopped by the optical chopper (12), the intensity of the excitation light is adjusted by the second attenuator (13), and then is emitted after being focused by the third plano-convex lens (14). During the focusing process, it is reflected by the third mirror (15) and finally focused on the sample (9). The focusing position of the excitation light is the same as the focusing position of the detection light. The detection module (V) includes: a PMT photomultiplier tube (11), a high-voltage power supply (16), and a lock-in amplifier (18). The PMT photomultiplier tube (11) detects the detection light emitted from the sample chamber module (III); the PMT photomultiplier tube (11) converts the optical signal into an electrical signal and inputs it into the lock-in amplifier (18); the PMT photomultiplier tube (11) is connected to the high-voltage power supply (16), and the high-voltage power supply (16) is used to apply a voltage to the PMT photomultiplier tube (11). The system control module (VI) includes: a junction box (19) and a computer (20). The junction box (19) simultaneously transmits the synchronization signal of the femtosecond laser (1) to the optical chopper (12) and the pulse power supply (17), and can trigger the optical chopper (12) and the pulse power supply (17) to work; the computer (20) is respectively connected to the femtosecond laser light source module (I), the detection light delay module (II), the junction box (19), and the lock-in amplifier (18) for signal connection.

2. The time-resolved second harmonic generation measurement system on an ultrafast time scale according to claim 1, characterized in that, the femtosecond laser (1) emits a laser with a wavelength of 800 nm or 1030 nm.

3. The time-resolved second harmonic generation measurement system on an ultrafast time scale according to claim 1, characterized in that, the optical parametric amplifier (3) generates a laser with a continuously adjustable wavelength of 200 - 2000 nm.

4. The time-resolved second harmonic generation measurement system on an ultrafast time scale according to claim 1, characterized in that, the junction box (19) adopts a BNC-2121 type junction box.

5. A measurement method of the time-resolved second harmonic generation measurement system on an ultrafast time scale according to any one of claims 1 to 4, characterized in that, includes the following processes: Step 100: Connect all the devices of the time-resolved second harmonic generation measurement system. The high-voltage power supply (16) applies a voltage to the PMT photomultiplier tube (11). Step 200: The computer (20) controls the optical parametric amplifier (3) in the femtosecond laser light source module (I) to select a wavelength. Step 300: The computer (20) controls the femtosecond laser (1) to turn on. At this time, the femtosecond laser (1) transmits an electrical signal to the junction box (19), and the junction box (19) distributes this electrical signal to the optical chopper (12) and the pulse power supply (17) simultaneously. At this time, the optical chopper (12) chops the excitation light emitted by the optical parametric amplifier (3), and the output signal of the optical chopper (12) is transmitted to the lock-in amplifier (18). The pulse power supply (17) applies a pulsed voltage to the sample (9) to change the electric field in which the sample (9) is located. Step 400: The computer (20) controls the probe light delay module (II) to move. The system starts scanning and data acquisition until the probe light delay module (II) stops moving. Step 500: The PMT photomultiplier tube (11) converts the optical signal into an electrical signal and transmits it to the lock-in amplifier (18). Step 600: The lock-in amplifier (18) transmits the processed data to the computer (20) to display the required data information. Step 700: The probe light delay module (II) stops moving, and the system stops data acquisition.

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