A method and device for monitoring single molecule photoelectric signals based on a lens group test rod

Abstract

The present application relates to the technical field of signal testing, and particularly relates to a single-molecule photoelectric signal monitoring method and device based on a lens group test rod, which comprises the following steps: laser passes through an optical parametric amplifier, an optical attenuating sheet and an optical power detector, and enters a climbing unit in the form of circularly polarized excitation light or linearly polarized excitation light; is reflected to the lens group test rod installed in a test cavity of a comprehensive physical property measurement system; is then focused on a single-molecule device through the lens group; the lens group of the lens group test rod is adjusted to perform multi-dimensional regulation and control on the single-molecule device; a probe of the comprehensive physical property measurement system monitors the conductance of the single-molecule device; and an optical signal detection and amplification unit cooperates with a computer to process the optical signal. The method and device provided by the present application can simultaneously realize the monitoring of multi-dimensional single-molecule photoelectric signals of single-molecule photoelectric combination, single-molecule fluorescence and single-molecule spin control.

Description

Technical Field

[0001] This invention relates to the field of signal testing technology, and in particular to a method and apparatus for monitoring single-molecule photoelectric signals based on a lens group test rod. Background Technology

[0002] Femtosecond laser technology plays a vital role in various fields such as biomedicine and optoelectronic information industry. With the advancement of science and technology, the demand for high-performance femtosecond lasers is constantly growing. High-repetition-rate femtosecond lasers, due to their advantages such as higher time resolution, pulse stability, and high energy, are gradually being applied in molecular electronics, enabling the detection of single-molecule excited-state characteristics on the pico-femtosecond timescale, as well as the detection of chemical reactions, charge transfer, and energy transfer dynamics.

[0003] The Power Physical Property Measurement System (PPMS) is a measurement platform that integrates fully automated methods for measuring various physical properties, including magnetism, electricity, thermal properties, and even morphology. Equipped with different cryogens, it can provide extremely low temperatures as low as 50 milliklvin and a strong magnetic field of 9 Tesla. It features a built-in high-vacuum system and magnetic shielding system, allowing the test chamber to achieve vacuum conditions quickly, while the escape magnetic field of the strong magnet is less than 5 Gauss at the edge of the main unit's casing. Based on the PPMS's high vacuum conditions, applicable ultra-low temperatures, and strong magnetic fields, and the fact that small optoelectronic devices can be physically connected to the PPMS's test sample rod, it has gradually become an ideal testing platform for small optoelectronic devices, especially for the study of quantum behaviors such as the quantum Hall effect and the Coulomb blocking effect.

[0004] With the rapid development of nanotechnology, device miniaturization has become a research trend due to its advantages such as reduced losses and lower costs. Currently, mainstream single-molecule devices commonly use monolayer graphene as source / drain electrodes to bridge molecules. Based on graphene's ultrathinness and high conductivity, graphene single-molecule devices exhibit extremely high sensitivity. By applying source / drain bias voltages or using gate voltage, the relative energy levels of graphene and molecules can be tuned, enabling photoelectric response testing of molecular properties. While conductivity testing of single-molecule devices under room temperature and low-temperature vacuum conditions is relatively mature, the temporal resolution of photoexcitation detection under vacuum conditions remains low, and visualizing dynamic processes at the single-molecule level is difficult. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method and device for monitoring single-molecule photoelectric signals based on a lens group test rod, which can simultaneously realize the monitoring of multi-dimensional single-molecule photoelectric signals including single-molecule photoelectric coupling, single-molecule fluorescence and single-molecule spin manipulation.

[0006] This invention is achieved through the following technical solution:

[0007] A method for monitoring single-molecule photoelectric signals based on a lens group test rod, comprising the following steps:

[0008] S1: The laser emitted from the femtosecond laser passes through the optical parametric amplifier, optical attenuator, and optical power detector in sequence, and then enters the climbing unit in the form of circularly polarized or linearly polarized excitation light.

[0009] S2: Circularly polarized or linearly polarized excitation light is reflected by the climbing unit to the lens group test rod installed in the test cavity of the integrated physical property measurement system;

[0010] S3: Circularly polarized or linearly polarized excitation light is focused onto the single-molecule device through the lens group of the lens group test rod;

[0011] S4: Adjust the lens group of the lens group test rod to perform multi-dimensional control of the single-molecule device. After the probe of the comprehensive physical property measurement system monitors the conductivity of the single-molecule device, the optical signal detection and amplification unit and the computer work together to process the optical signal.

[0012] Furthermore, the lens group test rod includes a rod body, a lens group, and a sample stage. The lens group includes a first reflecting mirror, a dichroic filter, a first pinhole diaphragm, a second pinhole diaphragm, a 50 / 50 beam splitter, and an objective lens. The first reflecting mirror is rotatably mounted on the rod body and is perpendicular to the horizontal direction. The included angle, wherein the dual-color filter is rotatably mounted on the rod and located below the first reflecting mirror, and forms a negative angle with the horizontal direction. The first and second pinhole apertures are fixedly mounted on the rod and located below the dichroic filter, with the first and second pinhole apertures being concentrically arranged. The 50 / 50 beam splitter is rotatably mounted on the rod and located between the first and second pinhole apertures. The objective lens is fixedly mounted on the rod and located below the second pinhole aperture. The sample stage is fixedly mounted on the rod and located below the objective lens.

[0013] Furthermore, multi-dimensional regulation includes single-molecule photoelectric coupling regulation, single-molecule fluorescence visualization, single-molecule fluorescence lifetime analysis, and single-molecule spin regulation.

[0014] Furthermore, the method for single-molecule photoelectric coupling modulation is as follows:

[0015] S411: The first reflecting mirror and the 55 beam splitter are rotated out of the optical path. The laser emitted by the femtosecond laser passes through the optical parametric amplifier, the optical attenuator, and the optical power detector in sequence. The linearly polarized excitation light formed is then reflected by the dual-color filter of the lens group test rod after passing through the climbing unit. After passing through the first small aperture and the second small aperture, it is focused by the objective lens onto the single-molecule device with photoresponse characteristics placed on the sample stage.

[0016] S412: The probes of the integrated physical property measurement system monitor the conductivity of single-molecule devices with photoresponse characteristics.

[0017] Furthermore, a camera and an LED white light source are mounted on the top of the lens group test rod.

[0018] Furthermore, the method for visualizing single-molecule fluorescence is as follows:

[0019] S421: Turn on the LED white light source, rotate the first reflector out of the light path, and rotate the 50 / 50 beam splitter and the dual-color filter into the light path;

[0020] S422: By observing the surface of a fluorescent single-molecule device through a camera, the knob of the climbing unit is adjusted so that the laser emitted by the femtosecond laser passes sequentially through an optical parametric amplifier, an optical attenuator, and an optical power detector. The resulting linearly polarized excitation light passes through the climbing unit and is incident on the dual-color filter of the lens group test rod. After reflection, it passes through the first pinhole aperture, the 50 / 50 beam splitter, and the second pinhole aperture, and is then focused by the objective lens onto the fluorescent single-molecule device. Simultaneously, white light passes sequentially from above through the dual-color filter of the lens group test rod, is transmitted through the first pinhole aperture, the 50 / 50 beam splitter, and the second pinhole aperture, and is then focused by the objective lens to illuminate the fluorescent single-molecule device.

[0021] S423: Move the 50 / 50 beam splitter out of the optical path and turn off the LED white light source;

[0022] S424: A single-molecule device with fluorescence function emits fluorescence. The fluorescence and linearly polarized excitation light are collected again by the objective lens and transmitted upward. The linearly polarized excitation light is filtered at the position of the two-color filter, and the fluorescence enters the camera after passing through the two-color filter, realizing the visualization of single-molecule excited state fluorescence.

[0023] The optimized optical signal detection and amplification unit includes a monochromator, a photomultiplier tube, a single-photon counter, and a lock-in amplifier connected in sequence.

[0024] Furthermore, the method for single-molecule fluorescence lifetime analysis is as follows:

[0025] S431: Turn on the LED white light source, rotate the first reflector out of the light path, and rotate the 50 / 50 beam splitter and the dual-color filter into the light path;

[0026] S432: By observing the surface of a fluorescent single-molecule device through a camera, the knob of the climbing unit is adjusted so that the laser emitted by the femtosecond laser passes sequentially through an optical parametric amplifier, an optical attenuator, and an optical power detector. The resulting linearly polarized excitation light passes through the climbing unit and is incident on the dual-color filter of the lens group test rod. After reflection, it passes through the first pinhole aperture, the 50 / 50 beam splitter, and the second pinhole aperture, and is then focused by the objective lens onto the fluorescent single-molecule device. Simultaneously, white light passes sequentially from above through the dual-color filter of the lens group test rod, is transmitted through the first pinhole aperture, the 50 / 50 beam splitter, and the second pinhole aperture, and is then focused by the objective lens onto the fluorescent single-molecule device.

[0027] S433: Move the 55 beam splitter out of the optical path and the first reflector into the optical path. Turn off the LED white light source. The single-molecule device with fluorescence function emits fluorescence. The fluorescence and linearly polarized excitation light are collected again by the objective lens and transmitted upward. The linearly polarized excitation light is filtered at the position of the two-color filter. After passing through the two-color filter, the fluorescence is reflected by the first reflector out of the lens group test rod.

[0028] S434: The fluorescence reflected from the test rod of the lens group is collected by optical fiber and enters the monochromator. The signal from the monochromator is detected by a photomultiplier tube and then input into a single-photon counter. The single-photon counter transmits the number of collected photons to the computer after passing through a lock-in amplifier. The computer analyzes the fluorescence lifetime of the excited state using fluorescence lifetime software.

[0029] Furthermore, methods for single-molecule spin manipulation include single-molecule spin initialization and electrical readout, and single-molecule all-optical spin manipulation and detection.

[0030] The single-molecule spin initialization and electrical readout methods are as follows:

[0031] S441: Rotate the first reflecting mirror and the 55 beam splitter out of the optical path, and set a 1 / 4 wave plate in front of the climbing unit. The laser emitted by the femtosecond laser passes through the optical parametric amplifier, the optical attenuator, and the optical power detector in sequence. After passing through the 1 / 4 wave plate, it forms circularly polarized excitation light. After passing through the climbing unit, it enters the dual-color filter of the lens group test rod. After passing through the first small aperture and the second small aperture, it is focused by the objective lens onto the single-molecule device placed on the sample stage.

[0032] S442: The free radical of the single-molecule device absorbs photons, which excites electrons to jump from a low energy level to a high energy level, and then returns to the ground state through radiative transition. The electron spin is initialized and the initialization writing is completed by using photomagnetic coupling.

[0033] S443: The 1 / 4 wave plate rotates periodically to control the direction of the circularly polarized excitation light, and the spin is read out by the electrical Rabi measurement method;

[0034] The method for single-molecule all-optical spin modulation and detection is as follows:

[0035] S451: Turn on the LED white light source, rotate the first reflector out of the light path, and rotate the 50 / 50 beam splitter and the dual-color filter into the light path;

[0036] S452: Observe the surface of a single-molecule device with fluorescence function and dual radical molecular functional side chains through a camera, and adjust the knob of the climbing unit to make the laser hit the single-molecule device with fluorescence function and dual radical molecular functional side chains.

[0037] S453: Move the 55 beam splitter out of the optical path, turn off the LED white light source, and set a 1 / 4 wave plate in front of the climbing unit. Rotate the 1 / 4 wave plate periodically. The laser emitted by the femtosecond laser passes through the optical parametric amplifier, optical attenuator, and optical power detector in sequence. After passing through the 1 / 4 wave plate, it forms circularly polarized excitation light. After passing through the climbing unit, it is incident on the dual-color filter of the lens group test rod and reflected through the first and second pinhole apertures. Then, it is focused by the objective lens onto a single-molecule device with fluorescence function and dual free radical molecular side chains.

[0038] S454: The first mirror is moved into the optical path. The single-molecule device with fluorescence function and dual radical molecular functional side chain emits fluorescence. The fluorescence and circularly polarized excitation light are collected again by the objective lens and transmitted upward. The circularly polarized excitation light is filtered at the position of the two-color filter. After passing through the two-color filter, the fluorescence is reflected by the first mirror out of the lens group test rod.

[0039] S455: The fluorescence reflected from the test rod of the lens group is collected by optical fiber and enters the monochromator. The signal from the monochromator is detected by a photomultiplier tube and then input into a single-photon counter. The single-photon counter transmits the number of collected photons to the computer after passing through a lock-in amplifier. The computer analyzes the fluorescence lifetime of the excited state through fluorescence lifetime software to complete the all-optical spin modulation and detection of a single molecule.

[0040] A single-molecule photoelectric signal monitoring device based on a lens group test rod is used to execute a single-molecule photoelectric signal monitoring method based on a lens group test rod as described in any of the above claims. It includes a femtosecond laser, an optical parametric amplifier, an optical attenuator, an optical power detector, a quarter-wave plate, a climbing unit, a comprehensive physical property measurement system connected to a camera and an LED white light source, a lens group test rod, an optical signal detection and amplification unit, and a computer. The femtosecond laser, optical parametric amplifier, optical attenuator, and optical power detector are coupled sequentially. The quarter-wave plate is detachably and rotatably mounted between the climbing unit and the optical power detector. The lens group test rod is placed in the test cavity of the comprehensive physical property measurement system. The lens group test rod includes a rod body, a lens group, and a sample stage. The lens group includes a first reflecting mirror, a dual-color filter, a first pinhole aperture, a second pinhole aperture, a 50 / 50 beam splitter, and an objective lens. The first reflecting mirror is rotatably mounted on the rod body and is perpendicular to the horizontal direction. The included angle, wherein the dual-color filter is rotatably mounted on the rod and located below the first reflecting mirror, and forms a negative angle with the horizontal direction. The first and second pinhole apertures are fixedly mounted on the rod and located below the dual-color filter, with the first and second pinhole apertures being concentrically arranged. The 50 / 50 beam splitter is rotatably mounted on the rod and located between the first and second pinhole apertures. The objective lens is fixedly mounted on the rod and located below the second pinhole aperture. The sample stage is fixedly mounted on the rod and located below the objective lens. The single-molecule device to be detected is fixedly placed on the sample stage. The optical signal detection and amplification unit includes a monochromator, a photomultiplier tube, a single-photon counter, and a lock-in amplifier connected in sequence. The monochromator is coupled to the first reflector through an optical fiber. The lock-in amplifier is connected to a computer. The climbing unit includes a second reflector and a third reflector.

[0041] Beneficial effects of the invention:

[0042] The present invention provides a method and device for monitoring single-molecule photoelectric signals based on a lens group test rod, which has the following advantages:

[0043] 1. This invention combines a femtosecond laser with a comprehensive physical property measurement system through a lens group test rod, ensuring direct excitation of the laser pulse without additional pulse broadening, resulting in higher time resolution and enabling picosecond-level measurements;

[0044] 2. This invention can achieve photoelectric integration, which can not only complete ultra-low temperature and strong magnetic field tests based on a comprehensive physical property measurement system, but also realize photoexcitation function;

[0045] 3. This invention can realize fluorescence imaging of micro- and nano-structures or materials and picosecond-level fluorescence lifetime spectroscopy measurement, and can flexibly change the test environment and magnetic field to observe the dynamic process under different conditions;

[0046] 4. This invention has the potential to be applied to the spin manipulation of qubits, which is a cutting-edge science of spin manipulation. In addition to the manipulation of circularly polarized light, it can also realize the spin readout of circularly polarized light under electroluminescence. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the process of this invention.

[0048] Figure 2 This is a schematic diagram of the device of the present invention.

[0049] Figure 3 This is a schematic diagram of the structure of the graphene-based diarylene single-molecule device of the present invention.

[0050] Figure 4 These are the current-voltage characteristic curves of the single-molecule device of the present invention before and after excitation by 600 nm light.

[0051] Figure 5 This is a fluorescence lifetime diagram of the single-molecule device of the present invention.

[0052] Figure 6 This is a schematic diagram of the test results of the lens group of the present invention.

[0053] In the diagram: 1. Femtosecond laser; 2. Optical parametric amplifier; 3. Integrated physical property measurement system connected to a camera and LED white light source; 4. Climbing unit; 4-1. Second reflecting mirror; 4-2. Third reflecting mirror; 5. Optical signal detection and amplification unit; 5-1. Monochromator; 5-2. Photomultiplier tube; 5-3. Single photon counter; 5-4. Lock-in amplifier; 6. Computer; 7. Optical attenuator; 8. Optical power detector; 9. Quarter wave plate; 10. Lens group test rod; 10-1. Rod body; 10-2. Sample stage; 10-3. First reflecting mirror; 10-4. Two-color filter; 10-5. First pinhole aperture; 10-6. Second pinhole aperture; 10-7. 50 / 50 beam splitter; 10-8. Objective lens; 11. Graphene electrode source end; 12. Graphene electrode drain end; 13. Single diarylene molecule; 14. Silicon wafer. Detailed Implementation

[0054] A method for monitoring single-molecule photoelectric signals based on a lens group test rod includes the following steps, the flowchart of which is shown below. Figure 1 As shown:

[0055] S1: The laser emitted from the femtosecond laser passes through the optical parametric amplifier, optical attenuator, and optical power detector in sequence, and then enters the climbing unit in the form of circularly polarized or linearly polarized excitation light.

[0056] The climbing unit here can be composed of two mirrors, namely the second mirror and the third mirror, both of which are high-reflectivity aluminum mirrors. This allows the femtosecond laser to be directly introduced into the optical entrance of the lens group test rod, ensuring direct excitation of the laser pulse without additional pulse broadening, thus giving it higher time resolution and enabling picosecond-level measurements.

[0057] The output power of the laser, together with the optical attenuator, can be measured using an optical power detector to ensure that the optical power is within a range that will not damage the single-molecule device.

[0058] S2: Circularly polarized or linearly polarized excitation light is reflected by the climbing unit to the lens group test rod installed in the test cavity of the integrated physical property measurement system;

[0059] The integrated physical property measurement system is a measurement platform that integrates fully automated magnetic, electrical, thermal, and even morphological observation methods. By equipping different refrigerators, it can provide extremely low temperatures as low as 50 milliklvin; at the same time, it can provide a strong magnetic field of 9 Tesla. It has a built-in high vacuum system and magnetic shielding system, and the sample chamber can achieve vacuum conditions in a short time, while the escape magnetic field of the strong magnet is less than 5 Gauss at the edge of the main unit shell.

[0060] The tests involved in this invention are all conducted under vacuum conditions, with pressures less than [missing information]. The testing instrument is a comprehensive physical property measurement system. The temperature control of the sample is achieved by the pulse tube refrigerator provided by the comprehensive physical property measurement system. The magnetic field control is completed by the conductive cooling superconducting magnet provided by the comprehensive physical property measurement system. The optical excitation can be completed by a titanium-doped sapphire femtosecond laser. The optical parametric amplifier can be a narrow pulse width femtosecond optical parametric amplifier, which can realize broadband optical excitation in the wavelength range of 325 nm to 2500 nm. The laser pulse width is adjustable from hundreds of femtoseconds to sub-picoseconds, with picosecond-level time resolution.

[0061] Specifically, the lens group test rod includes a rod body, a lens group, and a sample stage. The lens group includes a first reflecting mirror, a dichroic filter, a first pinhole diaphragm, a second pinhole diaphragm, a 50 / 50 beam splitter, and an objective lens. The first reflecting mirror is rotatably mounted on the rod body and is perpendicular to the horizontal direction. The included angle, the dual-color filter is rotated and mounted on the rod body and located below the first reflecting mirror, and is at a negative angle to the horizontal direction. The first and second pinhole diaphragms are fixedly mounted on the rod and located below the dichroic filter, with the first and second pinhole diaphragms set concentrically. The 50 / 50 beam splitter is rotatably mounted on the rod and located between the first and second pinhole diaphragms. The objective lens is fixedly mounted on the rod and located below the second pinhole diaphragm. The sample stage is fixedly mounted on the rod and located below the objective lens.

[0062] S3: Circularly polarized or linearly polarized excitation light is focused onto the single-molecule device through the lens group of the lens group test rod;

[0063] S4: Adjust the lens group of the lens group test rod to perform multi-dimensional control of the single-molecule device. After the probe of the comprehensive physical property measurement system monitors the conductivity of the single-molecule device, the optical signal detection and amplification unit and the computer work together to process the optical signal.

[0064] Specifically, multi-dimensional regulation includes single-molecule photoelectric coupling regulation, single-molecule fluorescence visualization, single-molecule fluorescence lifetime analysis, and single-molecule spin regulation.

[0065] Furthermore, the method for single-molecule photoelectric coupling modulation is as follows:

[0066] S411: The first reflecting mirror and the 55 beam splitter are rotated out of the optical path. The laser emitted by the femtosecond laser passes through the optical parametric amplifier, the optical attenuator, and the optical power detector in sequence. The linearly polarized excitation light formed is then reflected by the dual-color filter of the lens group test rod after passing through the climbing unit. After passing through the first small aperture and the second small aperture, it is focused by the objective lens onto the single-molecule device with photoresponse characteristics placed on the sample stage.

[0067] S412: The probe of the integrated physical property measurement system monitors the conductivity of single-molecule devices with photoresponse characteristics, and transmits the amplified signal to the computer for display after being amplified by the optical signal detection and amplification unit.

[0068] For single-molecule optoelectronic modulation, graphene-based diarylene single-molecule devices can be used, as shown in the schematic diagram below. Figure 3 As shown in the figure, 11 is the graphene electrode source end, 12 is the graphene electrode drain end, 13 is a single diarylene molecule, and 14 is a silicon wafer; the graphene electrode source end and the graphene electrode drain end are both located above the silicon wafer, and the two ends of the single diarylene molecule are covalently connected to the graphene electrode source end and the graphene electrode drain end, respectively.

[0069] Because diarylene molecules undergo cyclization under ultraviolet light excitation and ring-opening under visible light irradiation, the open-ring and closed-ring states correspond to low and high conductivity, respectively. A temperature control system based on a comprehensive property measurement system allows for testing within a temperature range of 2 Kelvin to 300 Kelvin. At 180 Kelvin, with source-drain voltages ranging from −1 V to 1 V in 5 mV intervals, the current-voltage characteristic curves of this single-molecule device before and after excitation by 600 nm light were measured as follows: Figure 4 As shown.

[0070] from Figure 4 It can be seen that photoexcitation, as a variable, leads to a significant decrease in the current-voltage characteristic curve after excitation, proving that the diarylene molecule in the graphene-based diarylene single-molecule device has undergone a ring-opening reaction.

[0071] Furthermore, the conductivity of ring-opening and ring-closing reactions of diarylene molecules can be monitored by switching the wavelength of the excitation light. Reversible molecular switching can be achieved through repeated visible or ultraviolet light excitation. Magnetic fields and temperatures can also be flexibly applied and controlled to investigate the photoreaction rate at different temperatures, and to enhance the selectivity of the ring-opening and ring-closing reactions to the optimal wavelength by applying a magnetic field.

[0072] Furthermore, a camera and an LED white light source are mounted on the top of the lens group test rod.

[0073] Furthermore, the method for visualizing single-molecule fluorescence is as follows:

[0074] S421: Turn on the LED white light source, rotate the first reflector out of the light path, and rotate the 50 / 50 beam splitter and the dual-color filter into the light path;

[0075] S422: By observing the surface of a fluorescent single-molecule device through a camera, adjusting the knob of the climbing unit allows the laser emitted by the femtosecond laser to pass sequentially through an optical parametric amplifier, an optical attenuator, and an optical power detector. The resulting linearly polarized excitation light then passes through the climbing unit and is incident on the dual-color filter of the lens group test rod. After reflection, it passes through the first pinhole aperture, the 50 / 50 beam splitter, and the second pinhole aperture, and is then focused by the objective lens onto the fluorescent single-molecule device. Simultaneously, white light passes sequentially from above through the dual-color filter of the lens group test rod, is transmitted through the first pinhole aperture, the 50 / 50 beam splitter, and the second pinhole aperture, and is then focused by the objective lens to illuminate the fluorescent single-molecule device. This illumination facilitates observation through the camera and ensures that the laser light is directed onto the surface of the fluorescent single-molecule device.

[0076] S423: Move the 50 / 50 beam splitter out of the optical path and turn off the LED white light source;

[0077] S424: A single-molecule device with fluorescence function emits fluorescence. The fluorescence and linearly polarized excitation light are collected again by the objective lens and transmitted upward. The linearly polarized excitation light is filtered at the position of the two-color filter, and the fluorescence enters the camera after passing through the two-color filter, realizing the visualization of single-molecule excited state fluorescence.

[0078] Specifically, perylene diimide (PDI) single-molecule devices can be used in single-molecule fluorescence modulation methods. PDI molecules possess significant luminescent properties, emitting stable long-wavelength fluorescence after short-wavelength excitation. Excitation is performed using a 400 nm laser, and a 425 nm dual-color filter ensures complete filtering of the excitation light while allowing fluorescence to pass through. The optical path is then calibrated to ensure accurate laser incidence on the single-molecule device, exciting the molecule to an excited state. The molecule then decays back to its ground state, emitting fluorescence. With the dual-color filter filtering out the excitation light, only the sample's fluorescence can be observed by the camera. This method enables fluorescence imaging of micro / nanostructures or materials smaller than 50 nm.

[0079] The optimized optical signal detection and amplification unit includes a monochromator, a photomultiplier tube, a single-photon counter, and a lock-in amplifier connected in sequence.

[0080] Furthermore, the method for single-molecule fluorescence lifetime analysis is as follows:

[0081] S431: Turn on the LED white light source, rotate the first reflector out of the light path, and rotate the 50 / 50 beam splitter and the dual-color filter into the light path;

[0082] S432: By observing the surface of a fluorescent single-molecule device through a camera, the knob of the climbing unit is adjusted so that the laser emitted by the femtosecond laser passes sequentially through an optical parametric amplifier, an optical attenuator, and an optical power detector. The resulting linearly polarized excitation light passes through the climbing unit and is incident on the dual-color filter of the lens group test rod. After reflection, it passes through the first pinhole aperture, the 50 / 50 beam splitter, and the second pinhole aperture, and is then focused by the objective lens onto the fluorescent single-molecule device. Simultaneously, white light passes sequentially from above through the dual-color filter of the lens group test rod, is transmitted through the first pinhole aperture, the 50 / 50 beam splitter, and the second pinhole aperture, and is then focused by the objective lens onto the fluorescent single-molecule device.

[0083] S433: Move the 55 beam splitter out of the optical path and the first reflector into the optical path. Turn off the LED white light source. The single-molecule device with fluorescence function emits fluorescence. The fluorescence and linearly polarized excitation light are collected again by the objective lens and transmitted upward. The linearly polarized excitation light is filtered at the position of the two-color filter. After passing through the two-color filter, the fluorescence is reflected by the first reflector out of the lens group test rod.

[0084] S434: The fluorescence reflected from the test rod of the lens group is collected by optical fiber and enters the monochromator. The signal from the monochromator is detected by a photomultiplier tube and then input into a single-photon counter. The single-photon counter transmits the number of collected photons to the computer after passing through a lock-in amplifier. The computer analyzes the fluorescence lifetime of the excited state using fluorescence lifetime software.

[0085] The signal from the monochromator is detected by a photomultiplier tube and then input into a single-photon counter. The single-photon counter has a picosecond-level time resolution. After collecting a large number of photons, the relationship between the time delay and the number of photons collected can be statistically determined, thereby reflecting the fluorescence lifetime of the excited state. It can be used to study processes such as molecular conformational changes, intramolecular or intermolecular proton transfer.

[0086] This fluorescence lifetime is obtained as a result of statistical analysis of a large number of photons collected, when a sample is relatively... When excited by a short laser pulse, after a time delay The sample emits fluorescence. A high-repetition-rate laser continuously excites the sample over a certain period of time. The electrical signal from each excitation, along with the electrical signal emitted by the photomultiplier tube each time a photon is detected, is input into a single-photon counter. Since the laser pulse width is constant, the time for collecting photons varies. The fluorescence lifetime is obtained by classifying and statistically analyzing the collection time.

[0087] Single-molecule fluorescence lifetime analysis can also be performed using a 400 nm wavelength laser for excitation, equipped with a 425 nm dual-color filter to ensure complete filtering of the excitation light while allowing fluorescence to pass through. The single-molecule device can be a perylene diimide (PDI) single-molecule device. The fluorescence lifetime spectrum obtained by collecting the excited fluorescent photons is shown below. Figure 5 As shown.

[0088] Furthermore, methods for single-molecule spin manipulation include single-molecule spin initialization and electrical readout, and single-molecule all-optical spin manipulation and detection.

[0089] The single-molecule spin initialization and electrical readout methods are as follows:

[0090] S441: Rotate the first reflecting mirror and the 55 beam splitter out of the optical path, and set a 1 / 4 wave plate in front of the climbing unit. The laser emitted by the femtosecond laser passes through the optical parametric amplifier, the optical attenuator, and the optical power detector in sequence. After passing through the 1 / 4 wave plate, it forms circularly polarized excitation light. After passing through the climbing unit, it enters the dual-color filter of the lens group test rod. After passing through the first small aperture and the second small aperture, it is focused by the objective lens onto the single-molecule device placed on the sample stage.

[0091] S442: The free radical of the single-molecule device absorbs photons, which excites electrons to jump from a low energy level to a high energy level, and then returns to the ground state through radiative transition. The electron spin is initialized and the initialization writing is completed by using photomagnetic coupling.

[0092] S443: The 1 / 4 wave plate rotates periodically to control the direction of the circularly polarized excitation light, and the spin is read out by the electrical Rabi measurement method;

[0093] Specifically, single-molecule spin initialization and electrical readout can be achieved using graphene single-molecule devices with single-radical functional side chains. Radical molecules typically have unpaired electrons in their outer shell, giving them high reactivity and energy in their electronic structure. When a radical absorbs a photon, it excites electrons to transition from a lower energy level to a higher energy level, and then returns to the ground state via radiative transition. As a natural two-level system, radical molecules are easily manipulated; therefore, the ground state and excited state can be used as a two-level system. Spin initialization of electrons can be achieved using photomagnetic coupling, and spin readout can be performed using electrical Rabi measurements.

[0094] In the conductivity testing of single-molecule devices, the conductivity state can change due to external environmental factors such as temperature and gate voltage, as well as intramolecular interactions such as stereoelectronic effects and molecular conformational changes. Therefore, it is necessary to first find the optimal temperature and gate voltage configuration in a magnetic field-free state. Based on the PPMS system, which enables both temperature and magnetic control, a 0.1 Tesla magnetic field is applied to a single radical group at the optimal temperature, causing Zeeman splitting of the degenerate energy levels with ±1 / 2 spin magnetic quantum numbers in the ground and excited states.

[0095] Then, left-handed circularly polarized light can be applied to irradiate the free radical molecule, causing the electrons with the spin direction upward to be excited to the excited state and undergo spin flipping. When the electrons fall back to the ground state, single free radical electron spin polarization is achieved, and the initialization writing of the quantum bit state is completed.

[0096] By reading out the spin using the electrical Rabi measurement method, the time of magnetic field evolution can be calculated based on the Zeeman splitting formula, and then... After the required phase time, the left-hand circularly polarized light is converted into right-hand circularly polarized light. Here, an electric motor can be used to periodically rotate the quarter-wave plate to control the direction of the circularly polarized light.

[0097] According to the Zeeman effect, when a magnetic field strength is applied... At that time, the energy change of spin level splitting It is the following formula:

[0098] ;

[0099] in, It is the electronic Landes factor, It is the Bohr magneton.

[0100] Furthermore, the Rabi oscillation frequency is proportional to the energy change of the spin level splitting, i.e.

[0101] ;

[0102] in: The frequency of the Rabi oscillation. This represents Planck's constant.

[0103] From this, we can conclude that... The time required for phase is .

[0104] Then, right-handed circularly polarized light is irradiated onto the free radical molecule, causing the molecule located at a spin magnetic quantum number of _____. The ground state electron transitions to the excited state The energy level is used to complete the spin readout of the quantum bit state.

[0105] While controlling free radical molecules with left- or right-hand circularly polarized light, the Rabi oscillation spectrum of the conductivity between the ground state and the excited state can be obtained by Rabi measurement of the conductivity, thereby calculating the relaxation time and decoherence time of the spin quantum state.

[0106] The method for single-molecule all-optical spin modulation and detection is as follows:

[0107] S451: Turn on the LED white light source, rotate the first reflector out of the light path, and rotate the 50 / 50 beam splitter and the dual-color filter into the light path;

[0108] S452: Observe the surface of a single-molecule device with fluorescence function and dual radical molecular functional side chains through a camera, and adjust the knob of the climbing unit to make the laser hit the single-molecule device with fluorescence function and dual radical molecular functional side chains.

[0109] S453: Move the 55 beam splitter out of the optical path, turn off the LED white light source, and set a 1 / 4 wave plate in front of the climbing unit. Rotate the 1 / 4 wave plate periodically. The laser emitted by the femtosecond laser passes through the optical parametric amplifier, optical attenuator, and optical power detector in sequence. After passing through the 1 / 4 wave plate, it forms circularly polarized excitation light. After passing through the climbing unit, it is incident on the dual-color filter of the lens group test rod and reflected through the first and second pinhole apertures. Then, it is focused by the objective lens onto a single-molecule device with fluorescence function and dual free radical molecular side chains.

[0110] S454: The first mirror is moved into the optical path. The single-molecule device with fluorescence function and dual radical molecular functional side chain emits fluorescence. The fluorescence and circularly polarized excitation light are collected again by the objective lens and transmitted upward. The circularly polarized excitation light is filtered at the position of the two-color filter. After passing through the two-color filter, the fluorescence is reflected by the first mirror out of the lens group test rod.

[0111] S455: The fluorescence reflected from the test rod of the lens group is collected by optical fiber and enters the monochromator. The signal from the monochromator is detected by a photomultiplier tube and then input into a single-photon counter. The single-photon counter transmits the number of collected photons to the computer after passing through a lock-in amplifier. The computer analyzes the fluorescence lifetime of the excited state through fluorescence lifetime software to complete the all-optical spin modulation and detection of a single molecule.

[0112] Single-molecule all-optical spin modulation and detection methods can utilize single-molecule devices with functional side chains of diradical molecules.

[0113] The diradical composition has a specific three-level ground state with spin multiplicity of ±1 and 0, respectively. The ground state with a spin magnetic quantum number of ±1 has a higher energy level.

[0114] The optimal temperature and gate voltage configuration can be found first in the absence of a magnetic field. Based on the PPMS integrated property measurement system that can achieve both temperature and magnetic control, a 0.1 Tesla magnetic field is applied to the diradical group at the optimal temperature, causing the degenerate energy levels with spin magnetic quantum numbers of ±1 in the ground state and excited state to undergo Zeeman splitting.

[0115] When left-handed circularly polarized light is applied for excitation, electrons with spin-up are excited to an excited state with a spin magnetic quantum number of −1 and undergo spin flipping, falling back to the ground state with a spin magnetic quantum number of −1 and emitting fluorescence. At this time, the electron spin is down, completing spin polarization.

[0116] The formula based on the Zeeman effect, after... After the phase takes the required time, the left-hand circularly polarized light is converted into right-hand circularly polarized light. Here, an electric motor can be used to rotate the quarter-wave plate periodically, so that the polarization direction of the excitation light changes periodically between left-hand and right-hand circularly polarized light, thereby realizing the flipping of electron spin.

[0117] At this point, fluorescent photons are collected using a single-photon counter, and the fluorescence lifetime signal is acquired for Rabi measurement. A shorter fluorescence lifetime indicates that the electron is in a spin singlet state, while a longer lifetime indicates it is in a spin triplet state. Based on the Rabi oscillation spectrum of the fluorescence lifetime, the relaxation time and decoherence time of the spin quantum state can be calculated.

[0118] The single-molecule all-optical spin modulation and detection method provided by this invention maintains the pulse width of the laser pulse by using a self-designed lens group test rod, enabling femtosecond-level excitation. Furthermore, through the high-time-resolution time-correlated single-photon counting function, it can achieve picosecond-level resolution fluorescence lifetime measurement, which is basically consistent with the time order of spin flip time, enabling the manipulation and readout of electron spin flip.

[0119] A single-molecule photoelectric signal monitoring device based on a lens group test rod is provided for executing the single-molecule photoelectric signal monitoring method based on a lens group test rod described above. A schematic diagram of the device structure is shown below. Figure 2 As shown, it includes a femtosecond laser 1, an optical parametric amplifier 2, an optical attenuator 7, an optical power detector 8, a quarter-wave plate 9, a climbing unit 4, a comprehensive physical property measurement system 3 connected to a camera and an LED white light source, a lens group test rod 10, an optical signal detection and amplification unit 5, and a computer 6. The femtosecond laser, optical parametric amplifier, optical attenuator, and optical power detector are coupled sequentially. The quarter-wave plate is detachably and rotatably installed between the climbing unit and the optical power detector. The lens group test rod is placed in the test cavity of the comprehensive physical property measurement system and coupled to the climbing unit. A schematic diagram of the lens group test rod results is shown below. Figure 6 As shown, it includes a rod 10-1, a lens group, and a sample stage 10-2. The lens group includes a first reflecting mirror 10-3, a dichroic filter 10-4, a first pinhole aperture 10-5, a second pinhole aperture 10-6, a 50 / 50 beam splitter 10-7, and an objective lens 10-8. The first reflecting mirror is rotatably mounted on the rod and is perpendicular to the horizontal direction. The included angle, the dual-color filter is rotated and mounted on the rod body and located below the first reflecting mirror, and is at a negative angle to the horizontal direction. The first and second pinhole apertures are fixedly mounted on the rod and located below the dual-color filter, with the first and second pinhole apertures being concentrically positioned. A 50 / 50 beam splitter is rotatably mounted on the rod and located between the first and second pinhole apertures. An objective lens is fixedly mounted on the rod and located below the second pinhole aperture. A sample stage is fixedly mounted on the rod and located below the objective lens. The single-molecule device to be detected is fixedly placed on the sample stage. The optical signal detection and amplification unit includes a monochromator 5-1, a photomultiplier tube 5-2, a single-photon counter 5-3, and a lock-in amplifier 5-4 connected in sequence. The monochromator is coupled to the first reflector via an optical fiber. The lock-in amplifier is connected to a computer. The climbing unit includes a second reflector 4-1 and a third reflector 4-2.

[0120] In summary, the present invention provides a single-molecule photoelectric signal monitoring method and device based on a lens group test rod. By using a self-designed lens group test rod, femtosecond lasers are linked with a comprehensive physical property measurement system, enabling the simultaneous monitoring of multi-dimensional single-molecule photoelectric signals, including single-molecule photoelectric coupling, single-molecule fluorescence, and single-molecule spin manipulation.

[0121] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for monitoring single molecule photoelectric signals based on a lens group test rod, characterized by: Comprise the following steps: S1: the laser emitted from femtosecond laser passes through optical parametric amplifier, optical attenuator, optical power detector in turn, and enters the climbing unit in the form of circularly polarized excitation light or linearly polarized excitation light; S2: the circularly polarized excitation light or the linearly polarized excitation light is reflected by the climbing unit to a lens group test rod installed in a test cavity of the comprehensive property measurement system, the lens group test rod comprises a rod body, a lens group and a sample stage, the lens group comprises a first mirror, a dichroic filter, a first pinhole diaphragm, a second pinhole diaphragm, a 5:5 beam splitter and an objective lens, the first mirror is rotatably installed on the rod body and forms a positive angle with the horizontal direction, The dichroic filter is rotatably installed on the rod body and located below the first mirror and forms a negative angle with the horizontal direction, The first pinhole diaphragm and the second pinhole diaphragm are fixedly installed on the rod body and located below the dichroic filter, and the first pinhole diaphragm and the second pinhole diaphragm are concentrically arranged, the 5:5 beam splitter is rotatably installed on the rod body and located between the first pinhole diaphragm and the second pinhole diaphragm, the objective lens is fixedly installed on the rod body and located below the second pinhole diaphragm, the sample stage is fixedly installed on the rod body and located below the objective lens, and a camera and an LED white light source are installed at the top of the lens group test rod; S3: the circularly polarized excitation light or linearly polarized excitation light is focused on the single molecule device through the lens group of the lens group test rod; S4: adjusting the lens group of the lens group test rod carries out multi-dimensional regulation including single molecule photoelectric coupling regulation, single molecule fluorescence visualization, single molecule fluorescence lifetime analysis and single molecule spin regulation, after the probe of comprehensive physical property measurement system monitors the conductance of the single molecule device, the optical signal detection and amplification unit cooperates with the computer to process the optical signal.

2. The method of claim 1, wherein the lens group test bar is characterized by: The method of single molecule photoelectric coupling regulation is as follows: S411: rotate the first reflector and the five-five beam splitter out of the light path, the linearly polarized excitation light formed after the laser emitted by the femtosecond laser passes through the optical parametric amplifier, the optical attenuator, the optical power detector in turn, is reflected after the double color filter of the lens group test rod, and is focused on the single molecule device with light response characteristics placed on the sample stage by the objective lens after the first pinhole diaphragm and the second pinhole diaphragm; S412: the probe of comprehensive physical property measurement system monitors the conductance of the single molecule device with light response characteristics.

3. The method of claim 1, wherein the lens group test bar is characterized by: The method of single molecule fluorescence visualization is as follows: S421: turn on the LED white light source, rotate the first reflector out of the light path, and rotate the five-five beam splitter and the double color filter into the light path; S422: observe the surface of the single molecule device with fluorescence function through the camera, adjust the knob of the climbing unit, so that the linearly polarized excitation light formed after the laser emitted by the femtosecond laser passes through the optical parametric amplifier, the optical attenuator, the optical power detector in turn is reflected after the double color filter of the lens group test rod, and is focused on the single molecule device with fluorescence function by the objective lens after the first pinhole diaphragm, the five-five beam splitter, the second pinhole diaphragm; at the same time, the white light transmits through the double color filter of the lens group test rod in turn from the top, and then transmits through the first pinhole diaphragm, the five-five beam splitter and the second pinhole diaphragm, and then is focused together on the single molecule device with fluorescence function by the objective lens; S423: move the five-five beam splitter out of the light path, and turn off the LED white light source; S424: the single molecule device with fluorescence function emits fluorescence, the fluorescence and the linearly polarized excitation light are collected and transmitted upward by the objective lens, the linearly polarized excitation light is filtered at the position of the double color filter, and the fluorescence enters the camera after passing through the double color filter, realizing single molecule excited state fluorescence visualization.

4. The method of claim 1, wherein the lens group test bar is used to monitor the single molecule photoelectric signal. The optical signal detection and amplification unit comprises a monochromator, a photomultiplier tube, a single photon counter and a lock-in amplifier connected in sequence.

5. The method of claim 4, wherein the lens group test bar is configured to focus the single molecule photoelectric signal onto the detector. The method of single molecule fluorescence lifetime analysis is as follows: S431: turn on the LED white light source, rotate the first reflector out of the light path, and rotate the five-five beam splitter and the double color filter into the light path; S432: Observe the surface of the single-molecule device with fluorescence function through the camera, adjust the knob of the climbing unit, and make the laser emitted by the femtosecond laser pass through the optical parametric amplifier, the optical attenuator, and the optical power detector in turn, form linearly polarized excitation light, and then enter the double-color filter of the lens group test rod after the climbing unit, and then reflect through the first pinhole diaphragm, the 50 / 50 beam splitter, and the second pinhole diaphragm, and then focus on the single-molecule device with fluorescence function by the objective lens; at the same time, the white light passes through the double-color filter of the lens group test rod in turn, and then transmits through the first pinhole diaphragm, the 50 / 50 beam splitter, and the second pinhole diaphragm, and then focus on the single-molecule device with fluorescence function by the objective lens; S433: Move the 50 / 50 beam splitter out of the optical path, move the first mirror into the optical path, turn off the LED white light source, and the single-molecule device with fluorescence function emits fluorescence, which is collected by the objective lens and transmitted upward together with the linearly polarized excitation light, and the linearly polarized excitation light is filtered at the position of the double-color filter, and the fluorescence is reflected out of the lens group test rod by the first mirror; S434: The fluorescence reflected out of the lens group test rod is collected by the optical fiber and enters the monochromator, the signal from the monochromator is detected by the photomultiplier tube and then input into the single-photon counter, the number of collected photons is transmitted to the computer through the lock-in amplifier, and the computer analyzes the fluorescence lifetime of the excited state through the fluorescence lifetime software.

6. The method of claim 1, wherein the lens group test bar is used to monitor the single molecule photoelectric signal. The method for single-molecule spin regulation includes single-molecule spin initialization and electrical readout, and single-molecule all-optical spin regulation and detection: The method for single-molecule spin initialization and electrical readout is as follows: S441: Rotate the first mirror and the 50 / 50 beam splitter out of the optical path, and set a 1 / 4 wave plate before the climbing unit, the laser emitted by the femtosecond laser passes through the optical parametric amplifier, the optical attenuator, and the optical power detector in turn, and then passes through the 1 / 4 wave plate to form circularly polarized excitation light, and then enters the double-color filter of the lens group test rod after the climbing unit, and then passes through the first pinhole diaphragm and the second pinhole diaphragm, and then focuses on the single-molecule device placed on the sample stage by the objective lens; S442: The free radicals of the single-molecule device absorb photons, and the excited electrons jump from the low energy level to the high energy level, and then return to the ground state by radiation transition, and the spin of the electrons is initialized and written by the optical magnetic combination; S443: The 1 / 4 wave plate is periodically rotated to control the direction of the circularly polarized excitation light, and the spin is read out by the electrical Rabi measurement method; The method for single-molecule all-optical spin regulation and detection is as follows: S451: Turn on the LED white light source, rotate the first mirror out of the optical path, and rotate the 50 / 50 beam splitter and the double-color filter into the optical path; S452: Observe the surface of the single-molecule device with fluorescence function and double-free-radical molecular function side chains through the camera, adjust the knob of the climbing unit, and make the laser hit the single-molecule device with fluorescence function and double-free-radical molecular function side chains; S453: move the five-five beam splitter out of the light path, turn off the LED white light source, and set a 1 / 4 wave plate before the climbing unit and make the 1 / 4 wave plate rotate periodically, the laser emitted by the femtosecond laser passes through the optical parametric amplifier, the optical attenuation sheet, and the optical power detector in turn, forms circularly polarized excitation light through the 1 / 4 wave plate, and then is reflected by the double-color filter after the lens group test rod after the climbing unit, and is focused by the objective lens to irradiate on the single-molecule device with fluorescence function and double free radical molecular function side chain through the first pinhole diaphragm and the second pinhole diaphragm; S454: move the first mirror into the light path, the single-molecule device with fluorescence function and double free radical molecular function side chain emits fluorescence, the fluorescence and the circularly polarized excitation light are collected and transmitted upward by the objective lens, the circularly polarized excitation light is filtered at the position of the double-color filter, and the fluorescence is reflected out of the lens group test rod by the first mirror after passing through the double-color filter; S455: the fluorescence reflected out of the lens group test rod is collected by the optical fiber and enters the monochromator, the signal from the monochromator is detected by the photomultiplier tube and then input into the single-photon counter, the single-photon counter transmits the collected photon number to the computer through the lock-in amplifier, the computer analyzes the fluorescence lifetime of the excited state through the fluorescence lifetime software, and completes the single-molecule all-optical spin regulation and detection.

7. A single molecule opto-electronic signal monitoring apparatus based on lens group test rod for performing a single molecule opto-electronic signal monitoring method based on lens group test rod according to any one of claims 1 to 6, characterized in that: The application relates to a comprehensive physical property measurement system comprising a femtosecond laser, an optical parametric amplifier, an optical attenuating sheet, an optical power detector, a 1 / 4 wave plate, a climbing unit, a camera and an LED white light source, a lens group test rod, an optical signal detection and amplification unit and a computer, wherein the femtosecond laser, the optical parametric amplifier and the optical attenuating sheet are sequentially coupled, the 1 / 4 wave plate is detachably and rotatably arranged between the climbing unit and the optical power detector, the lens group test rod is arranged in a test cavity of the comprehensive physical property measurement system, the lens group test rod comprises a rod body, a lens group and a sample stage, the lens group comprises a first reflector, a dichroic filter, a first pinhole diaphragm, a second pinhole diaphragm, a 50 / 50 beam splitter and an objective lens, the first reflector is rotatably arranged on the rod body and forms a positive angle with the horizontal direction, the dichroic filter is rotatably arranged on the rod body below the first reflector and forms a negative angle with the horizontal direction, the first pinhole diaphragm and the second pinhole diaphragm are fixedly arranged on the rod body below the dichroic filter, the first pinhole diaphragm and the second pinhole diaphragm are concentrically arranged, the 50 / 50 beam splitter is rotatably arranged on the rod body between the first pinhole diaphragm and the second pinhole diaphragm, the objective lens is fixedly arranged on the rod body below the second pinhole diaphragm, the sample stage is fixedly arranged on the rod body below the objective lens, a single-molecule device to be detected is fixedly arranged on the sample stage, the optical signal detection and amplification unit comprises a monochromator, a photomultiplier tube, a single-photon counter and a lock-in amplifier which are sequentially connected, the monochromator is coupled with the first reflector through an optical fiber, the lock-in amplifier is connected with the computer, and the climbing unit comprises a second reflector and a third reflector. ​​

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