Optical frequency modulation and same-frequency electric signal output device of laser pulse

Abstract

The invention discloses an optical frequency modulation and same-frequency electric signal output device for laser pulses, and relates to the technical field of optical frequency modulation. According to the device, an optical chopper is arranged between two diaphragms, fan blades of the optical chopper are covered with film coating layers, laser is reflected after irradiating the film coating layers on the fan blades, the repetition frequency of the laser is adjusted by controlling the rotating speed of the optical chopper, and laser pulses of different frequencies passing through the diaphragms are obtained. The optical sensor is arranged on a laser reflection path of the optical chopper and can receive reflected laser pulses to form light currents through the photoelectric effect, and the light currents are converted into electrical pulse signals with the same frequency as the laser pulses passing through the diaphragm through the signal collecting and converting circuit and then output. According to the invention, the adaptability of optical frequency modulation is improved, and the reflected laser is utilized to form an electric signal with the same frequency as the laser pulse passing through the diaphragm so as to be used for device control because the passing and reflecting frequencies of the laser by the optical chopper are the same.

Description

Technical Field

[0001] This application relates to the field of optical frequency modulation technology, and particularly to an optical frequency modulation of laser pulses and a co-frequency electrical signal output device. Background Art

[0002] Currently, with the development of the application of lasers in time-resolved technology, new requirements have been put forward for the modulation drive of lasers. For example, time-resolved photoluminescence spectroscopy based on time-correlated single photon counting (TCSPC) technology has become a classic method for measuring the fluorescence lifetime of luminescent materials due to its simple operability and reliable stability. The test range of the time-resolved lifetime spectrum obtained by this method is usually jointly determined by the hardware performance of TCSPC and the repetition frequency of the laser. Generally, the time window of TCSPC satisfies a time scale of 1 ns or more, but the limitations encountered in practical applications mostly stem from the singularity of the laser repetition frequency. Therefore, in actual tests, it is necessary to equip lasers or stroboscopic light sources with different repetition frequencies according to the lifetime characteristics of the material to meet different test requirements. This greatly increases the complexity and cost of the system, and at the same time limits the possibility of applying low-cost continuous lasers to time-resolved technology.

[0003] In the prior art, the frequency modulation solution has a method of post-end modulation based on the nonlinear photoelectric effect of electro-optic crystals. Its principle is to modulate light at the backend of the system based on the nonlinear photoelectric effect of expensive electro-optic crystals, also known as electro-optic switch frequency modulation. Electro-optic crystal frequency modulation refers to applying a voltage to an electro-optic crystal such as KD*P to generate the Pockels effect to change the refractive index of the material to block or pass a certain polarized light beam. For example, for a linearly polarized laser beam, if a suitable voltage is applied externally to the KD*P crystal, due to the Pockels effect, the vibration direction of the linearly polarized light passing through the crystal back and forth changes by π / 2, and at this time the light beam cannot pass through the resonant cavity. If no voltage is applied to the KD*P crystal, the vibration direction of the linearly polarized light passing through the crystal back and forth remains unchanged, and the light beam can pass through. Due to the external excitation, the number of particles in the upper energy level increases rapidly. When the voltage on the crystal is suddenly removed, the light beam can freely pass through the electro-optic crystal. In this way, the function of frequency conversion of optical signals is realized by controlling the passing and non-passing of the light beam.

[0004] However, the electro-optic crystal frequency modulation method has certain requirements for the parameters of the light beam itself. When the light beam is not linearly polarized light, a polarizer needs to be added to make the input light have linear polarization characteristics. At the same time, when modulating the frequency in the face of a high-energy laser source, the electro-optic crystal has a large instantaneous thermal effect, which will reduce the service life of the electro-optic crystal, and the huge thermal effect, that is, the phonon effect, will cause the delay generated by the electro-optic switching effect, resulting in a reduction in the instantaneousness of the switching effect. And in time-resolved technology, an electrical signal synchronized with the laser pulse is often required to control the device. The existing synchronized electrical signal usually uses the driving electrical signal of an external or built-in signal transmitter. However, there is a delay and resistance between the driving electrical signal and the actual frequency modulation signal of the laser pulse, resulting in the inability to synchronize the two with high precision. In summary, the existing methods have problems of low adaptability, low efficiency, and inability to output synchronized electrical signals in cooperation. Summary of the Invention

[0005] An optical frequency modulation and synchronized electrical signal output device for laser pulses provided by an embodiment of this specification is used to partially solve the problems existing in the prior art.

[0006] The embodiment of this specification adopts the following technical solutions:

[0007] This specification provides an optical frequency modulation and synchronized electrical signal output device for laser pulses, including:

[0008] Two diaphragms. The laser emitted by the target light source enters the light passing holes of the two diaphragms. The two diaphragms are used to calibrate and limit the transmission area of the target light source;

[0009] An optical chopper, which is arranged between the two diaphragms. The fan blades are covered with a coating. The laser emitted by the target light source is reflected after irradiating the coating on the fan blades. By controlling the rotation speed of the optical chopper, the repetition frequency of the laser is adjusted to obtain laser pulses with different frequencies passing through the two diaphragms;

[0010] An optical sensor, which is arranged on the reflection path of the laser by the optical chopper, is used to receive the laser pulse obtained by reflection synchronized with the laser pulse passing through the two diaphragms and form a photocurrent through the photoelectric effect of the optical sensor;

[0011] A signal acquisition and conversion circuit, which is electrically connected to the optical sensor, is used to receive the photocurrent and convert it into an electrical pulse signal synchronized with the laser pulse passing through the two diaphragms and then output it.

[0012] Optionally, the device further includes: a converging optical element, which is arranged on the reflection optical path of the laser by the coating, is used to turn and focus the laser reflected by the coating to form a laser pulse trigger signal synchronized with the laser pulse passing through the two diaphragms;

[0013] The optical sensor is arranged on the turning path of the converging optical element for the laser, and is used to receive the laser pulse trigger signal and form a photocurrent through the photoelectric effect of the optical sensor.

[0014] Optionally, the signal acquisition and conversion circuit further includes a comparator and a feedback circuit. The signal acquisition and conversion circuit is further configured to perform real-time frequency statistics on the electrical pulse signal, and then compare the real-time frequency of the electrical pulse signal with the preset laser pulse frequency passing through the two diaphragms through the comparator, and perform real-time dynamic speed adjustment on the rotation speed of the optical chopper through the feedback circuit.

[0015] Optionally, the optical frequency modulation and same-frequency electrical signal output device of the laser pulse further includes:

[0016] Two reflectors, which have three degrees of freedom in the up-down, left-right, and pitch directions, and adjust the optical path of the laser emitted by the target light source through the two reflectors, so that the laser enters the light passing holes of the two diaphragms.

[0017] Optionally, the optical frequency modulation and same-frequency electrical signal output device of the laser pulse further includes:

[0018] An optical breadboard for providing a horizontal and stable platform, and the two diaphragms, the optical chopper, the converging optical element, the optical sensor, and the signal acquisition and conversion circuit are all installed on the optical breadboard.

[0019] Optionally, when the light source band is the ultraviolet band, the coating layer is an aluminum reflective film;

[0020] When the light source band is the visible band, the coating layer is a silver reflective film;

[0021] When the light source band is the infrared band, the coating layer is a gold reflective film;

[0022] When the light source band is greater than the preset spectral band, the coating layer is a dielectric reflective film.

[0023] Optionally, the fan blades of the optical chopper are flat fan blades or sloped fan blades.

[0024] Optionally, the optical sensor is any one of a photoresistor, a silicon photodetector, or a quantum well sensor.

[0025] Optionally, the signal acquisition and conversion circuit further includes a comparator and a Bluetooth module. The real-time frequency of the electrical pulse signal is compared with the preset laser pulse frequency passing through the two diaphragms through the comparator. If it is determined that the fan blades of the optical chopper generate dynamic jitter, the rotation speed of the optical chopper is adjusted remotely in real time through the Bluetooth module.

[0026] Optionally, the signal acquisition and conversion circuit further includes a comparator and an error sensing lamp. The comparator compares the real-time frequency of the electrical pulse signal with the preset laser pulse frequency passing through the two diaphragms. If it is determined that the rotational speed of the fan blades of the optical chopper deviates from the preset rotational speed and exceeds the preset error range, the error sensing lamp lights up for warning.

[0027] The above at least one technical solution adopted in the embodiments of this specification can achieve the following beneficial effects:

[0028] The optical frequency modulation of laser pulses and the output device of the same-frequency electrical signal of the present invention include two diaphragms, an optical chopper, an optical sensor, and a signal acquisition and conversion circuit. The two diaphragms are used to calibrate and limit the transmission area of the target light source. The optical chopper is arranged between the two diaphragms, and its fan blades are covered with a coating. After the laser irradiates the coating on the fan blades, it is reflected. By controlling the rotation speed of the optical chopper, the repetition frequency of the laser is adjusted to obtain laser pulses with different frequencies. The optical sensor is arranged on the reflection path of the laser by the optical chopper. It can receive the reflected laser pulses to form a photocurrent through the photoelectric effect, and is converted into an electrical pulse signal with the same frequency as the laser pulses through the signal acquisition and conversion circuit and then output.

[0029] The present invention does not limit the performance of the light source itself, greatly improves the universality of the application, can withstand the use conditions of high-intensity lasers, improves the adaptability and efficiency of optical frequency modulation. At the same time, since the passing and reflection frequencies of the laser by the optical chopper are the same, the reflected laser is utilized through the optical sensor and the signal acquisition and conversion circuit to form an electrical signal with the same frequency as the laser pulses passing through the diaphragm for device control. Description of the Drawings

[0030] The drawings described herein are used to provide a further understanding of the present application, and constitute a part of the present application. The schematic embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation of the present application. In the drawings:

[0031] Figure 1a It is a schematic diagram of the light-passing state of an optical frequency modulation of laser pulses and an output device of the same-frequency electrical signal provided by this specification;

[0032] Figure 1b It is a schematic diagram of the light-blocking state of an optical frequency modulation of laser pulses and an output device of the same-frequency electrical signal provided by this specification;

[0033] Figure 2a It is a schematic diagram of an optimized optical frequency modulation of laser pulses and an output device of the same-frequency electrical signal in the light-passing state provided by this specification;

[0034] Figure 2bSchematic diagram of an optimized laser pulse optical frequency modulation and co-frequency electrical signal output device under a light-shielded state provided in this specification;

[0035] Figure 3 Schematic diagram of the function flow of a laser pulse optical frequency modulation and co-frequency electrical signal output device provided in this specification;

[0036] Figure 4 Schematic diagram of the sloped fan blade of a coated film reflective optical chopper provided in this specification;

[0037] Figure 5 Schematic diagram of the flat fan blade of a coated film reflective optical chopper provided in this specification;

[0038] Figure 6 Schematic diagram of fluorescence lifetime measurement using a laser pulse optical frequency modulation and co-frequency electrical signal output device provided in this specification. Detailed implementation manners

[0039] To make the objectives, technical solutions, and advantages of this specification clearer, the technical solutions of this application will be clearly and completely described below in conjunction with the specific embodiments of this specification and the corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all of the embodiments. Based on the embodiments in this specification, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of this application.

[0040] The following details the technical solutions provided by each embodiment of this application in conjunction with the drawings.

[0041] Currently, there are mainly two frequency modulation solutions: the front-end modulation method based on modulating and driving a laser using an external signal and the back-end modulation method based on the nonlinear optoelectronic effect of an electro-optic crystal. Among them, for the front-end modulation method based on modulating and driving a laser using an external signal, the principle is to directly modulate the driving circuit of the laser through an external signal generator at the front end of the system, thereby achieving laser frequency modulation. This method requires the laser itself to have a modulation interface for electrical signal input, and the input low-frequency electrical signal can satisfy one of the conditions for laser generation, namely the population inversion condition. In reality, however, a lower-frequency electrical drive signal, especially an electrical drive signal below 1 KHz, often makes it difficult for the light source to generate stable laser light.

[0042] For the back-end modulation method based on the nonlinear optoelectronic effect of an electro-optic crystal, its principle is to modulate light at the back end of the system based on the nonlinear optoelectronic effect of an expensive electro-optic crystal. This method has certain requirements for the parameters of the light beam itself, and there is no high-precision synchronous co-frequency reference signal, and it is necessary to further split the beam through a beam splitter later, which will cause energy waste and loss.

[0043] Figure 1a This is a schematic diagram of the light-passing state of an optical frequency modulation and co-frequency electrical signal output device for a laser pulse in this specification. Figure 1b This is a schematic diagram of the light-blocking state of an optical frequency modulation and co-frequency electrical signal output device for a laser pulse in this specification. As can be seen from Figure 1a and Figure 1b it can be seen that the optical frequency modulation and co-frequency electrical signal output device for a laser pulse includes: two apertures, namely the first aperture 5 and the second aperture 8, an optical chopper 7, an optical sensor 10, and a signal acquisition and conversion circuit 11. Figure 1a and Figure 1b also shows the target light source 1. The target light source 1 can be a visible light laser with high collimation and excellent monochromaticity.

[0044] As can be seen from the figure, in the light-passing state, the laser emitted by the target light source 1 enters the light-passing holes of the two apertures, the first aperture 5 and the second aperture 8, and the two apertures are used to calibrate and limit the transmission area of the target light source.

[0045] The optical chopper 7 is arranged between the two apertures, and its fan blades are covered with a flat and smooth coating. The laser emitted by the target light source 1 is reflected after irradiating on the coating on the fan blades. Correspondingly, the optical frequency modulation and co-frequency electrical signal output device for a laser pulse is in the light-blocking state. When the laser emitted by the target light source 1 irradiates on the gap between the fan blades, the optical frequency modulation and co-frequency electrical signal output device for a laser pulse is in the light-passing state.

[0046] Therefore, the repetition frequency of the laser can be adjusted by controlling the rotation speed of the optical chopper 7 to obtain laser pulses with different frequencies passing through the two apertures. The present invention is applicable to various target light sources and does not limit the laser parameters of the target light source, which can be specifically determined according to needs.

[0047] Furthermore, in one or more embodiments of this specification, for the coating on the fan blades of the optical chopper 7, when the light source band is the ultraviolet band, the coating can be an aluminum reflective film. When the light source band is the visible band, the coating can be a silver reflective film. When the light source band is the infrared band, the coating can be a gold reflective film. When the light source band is greater than the preset spectral band, the coating can be a dielectric reflective film. It can be seen that the present invention does not limit the performance of the light source itself, greatly improving the universality of applications, and can be widely applied to continuous lasers, pulsed lasers, or ordinary collimated light sources. At the same time, for different optical bands where the light source is located, a smooth and flat reflective coating corresponding to the band can be covered on the surface of the chopper to avoid the problem that traditional light-blocking choppers are easily damaged when used under high-power light illumination conditions.

[0048] An optical sensor 10 is disposed on the reflection path of the laser by the optical chopper 7, and is configured to receive the laser pulses obtained by reflecting the laser pulses having the same frequency as those passing through the two diaphragms, and form a photocurrent through the photoelectric effect of the optical sensor 10. The optical sensor 10 here can be any one of a photoresistor, a silicon photodetector, or a quantum well sensor.

[0049] A signal acquisition and conversion circuit 11 is electrically connected to the optical sensor 10, and is configured to receive the photocurrent, convert it into an electrical pulse signal having the same frequency as the laser pulses passing through the two diaphragms, and then output it. That is, the optical sensor 10 is triggered to change its electrical characteristics in the signal acquisition and conversion circuit 11 at the same frequency to obtain a high-precision real-time reference signal with the same frequency.

[0050] During the adjustment process, the design circuit of the rotation motor of the optical chopper 7 can be implemented by a wired connection control through a serial port based on a Field Programmable Gate Array (FPGA) circuit board, or can be adjusted by a wireless connection method such as Bluetooth or WiFi. Of course, only for illustration here, the rotation motor design circuit can also be a single-chip microcomputer or a Micro controller Unit (MCU), etc. The said wired connection method can be a serial port, CAN, GPIB, RJ45 network port, optical fiber interface, etc. The specific method to be adopted can be determined according to needs, and this specification does not limit this.

[0051] Figure 2a It is a schematic diagram of an optimized laser pulse optical frequency modulation and same-frequency electrical signal output device in a light-passing state in this specification. Figure 2b It is a schematic diagram of an optimized laser pulse optical frequency modulation and same-frequency electrical signal output device in a light-blocking state in this specification.

[0052] Consisting of Figure 2a and Figure 2b It can be seen that the laser pulse optical frequency modulation and same-frequency electrical signal output device may further include a converging optical element 9, which is disposed on the reflection optical path of the laser by the coating layer, and is configured to turn and focus the laser reflected by the coating layer to form a laser pulse trigger signal having the same frequency as the laser pulses passing through the two diaphragms. The above-mentioned optical chopper 7 can be placed at a specific angle to ensure that the reflected light beam can converge to the target position of the converging optical element 9 each time in the blocking state. The converging optical element 9 here can be an off-axis parabolic mirror.

[0053] An optical sensor 10 is disposed on the turning path of the laser by the converging optical element 9, and is configured to receive the laser pulse trigger signal and form a photocurrent through the photoelectric effect of the optical sensor.

[0054] Further, in one or more embodiments of this specification, the signal acquisition and conversion circuit 11 may further include a comparator and a feedback circuit. The signal acquisition and conversion circuit 11 is further configured to perform real-time frequency statistics on the electrical pulse signal, and then compare the real-time frequency of the electrical pulse signal with the preset laser pulse frequency passing through the two diaphragms through the comparator, and perform real-time dynamic rotational speed adjustment on the rotational speed of the optical chopper 7 through the feedback circuit.

[0055] The reference signal of the traditional frequency modulation method comes from the driven electrical signal. However, due to the delay and resistance between the driven electrical signal and the actual frequency modulation signal, the two cannot be synchronized with high precision. The present invention can ensure the high-precision coordination between the actual frequency modulation signal and the reference signal, and the fixed optical path delay difference between them can also be eliminated by software. In addition, in terms of portability, different types of chopper blades can be designed, which can be replaced at any time to achieve different frequency modulation ranges. The drive circuit of the rotating motor is added with wired connection control and wireless connection control operations, which can be miniaturized in volume and remotely controlled.

[0056] In addition, in one or more embodiments of this specification, refer Figure 2a and Figure 2b , the optical frequency modulation and same-frequency electrical signal output device of the laser pulse may further include two reflectors, a first reflector 2 and a second reflector 3. The two reflectors have three degrees of freedom in the up-down, left-right, and pitch directions. The optical path of the laser emitted by the target light source is adjusted through the two reflectors, so that the laser enters the light passing holes of the two diaphragms in the light passing state. By setting the two reflectors to adjust the laser optical path of the target light source, the dependence on the installation position of the target light source is eliminated, and the setting of the entire optical frequency modulation and same-frequency electrical signal output device of the laser pulse is made more free and convenient.

[0057] In addition, in one or more embodiments of this specification, refer Figure 2a and Figure 2b , the optical frequency modulation and same-frequency electrical signal output device of the laser pulse may further include an optical breadboard 4 for providing a horizontal and stable platform. The two diaphragms, the first diaphragm 5 and the second diaphragm 8, the optical chopper 7, the converging optical element 9, the optical sensor 10, and the signal acquisition and conversion circuit 11 are all installed on the optical breadboard 4. Of course, the optical chopper intelligent control unit 6 for adjusting the rotational speed of the optical chopper 7 may also be installed on the optical breadboard 4. Figure 2a and Figure 2b also shows an electrical signal output interface 12.

[0058] Further, in one or more embodiments of this specification, a 532nm semiconductor laser can be selected as the target light source 1 for the realization of the optical frequency modulation and homodyne electrical signal output device of the laser pulse, which not only meets the requirements of beam collimation, but also is sensitive to the human eye and easy to adjust with green light. Since this laser is a continuous light source, its frequency can be directly read out by an optical chopper without coefficient conversion of the frequency. The light beam emitted by the target light source 1 is respectively adjusted horizontally and pitchwise by the first reflector 2 and the second reflector 3 to ensure that it can pass through the first aperture 5 and the second aperture 8. Thus, it is ensured that the light beam can be modulated within the working space area of the anti-optical chopper 7. Among them, the first aperture 5, the intelligent control unit 6 of the optical chopper, the optical chopper 7, the second aperture 8, the off-axis paraboloid mirror 9, the optical sensor 10, the electronic signal acquisition and conversion circuit 11, and the electrical signal output interface are all placed on the optical breadboard for easy installation and calibration.

[0059] In the light-passing state, since the selected target light source 1 in this example is a 532nm semiconductor laser, the coating of the optical chopper 7 is selected as a silver reflective film, and the material of the off-axis paraboloid mirror 9 is preferably a silver film. After the light beam of the target light source 1 is modulated to the target working area by the first reflector 2 and the second reflector 3, the light beam can directly pass through the first aperture 5 and the second aperture 8 and be output to the external space optical path. This basic schematic process is as Figure 2a shown.

[0060] In the light-blocking state, at this time, the light beam emitted by the target light source 1 has been collimated in the working area under passing conditions. When the fan blade of the optical chopper 7 blocks the light beam, the coating on its surface will reflect the light beam to the off-axis paraboloid mirror 9. The off-axis paraboloid mirror 9 turns and converges the light beam to focus on the optical sensor 10, causing a change in the electrical characteristics of the optical sensor 10. Here, the resistance of the optical sensor 10 changes due to the photoconductive effect. At this time, the electronic signal acquisition and conversion circuit 11 will receive the change in the volt-ampere characteristic in the circuit and record the signal. When the homodyne electrical signal is needed, a reference homodyne output signal can be obtained by connecting through an optical transmission line to the electrical signal interface 12. Since this signal is recorded every time the fan blade blocks the light, it is homodyne with the modulation during light passing. Even if there is a deviation between the actual frequency modulation of the fan blade and the set value, the reference homodyne output signal will also change accordingly. Preferably, the reading of the electronic signal acquisition and conversion circuit 11 can be defined at the rising edge, that is, every time the light beam irradiates the initial change of the optical sensor 10, at which time the synchronization degree of the two is the highest.

[0061] Figure 3 This is a schematic diagram of the functional flow of an optical frequency modulation and homodyne electrical signal output device of a laser pulse in this specification, which is composed of Figure 3It can be seen that the light beam emitted by the light source is modulated into a pulsed signal with the required frequency by the coated film reflective optical chopper. In the light-passing state, when the size of the light beam is smaller than the gap between the fan blades of the optical chopper, the original light beam with instantaneous non-destructive output can be obtained to form a laser pulse with the required frequency. When the optical chopper blocks the light, the reflective coating on its surface will reflect the light beam to the off-axis parabolic mirror. The off-axis parabolic mirror changes the direction of the light beam and focuses it on the optical sensor. When the optical sensor is irradiated by light, the photoelectric effect will occur to form a photocurrent, which can be converted into an electrical pulse signal through the designed electronic signal acquisition and conversion circuit. The intensity of the output pulse signal can be manually adjusted and set according to the usage requirements. At the same time, the signal acquisition and conversion circuit can perform real-time frequency statistics on the output pulse signal, and compare and feedback the statistical result with the preset laser pulse frequency parameter passing through the two diaphragms, and dynamically feedback and adjust the rotation speed of the chopper in real time to ensure a high degree of consistency between the actual output frequency and the target parameter. Because the light beam signal after each light passing will be immediately blocked and reflected, even if the actual light pulse modulation changes due to insufficient driving force compared with the designed driving, the reference signal will also change in the same way at this time, so the two signals are highly accurate and in the same frequency. There is a fixed optical path delay between the two, and software can be used to compensate for the optical delay, so that the two can output with high precision and the same frequency. The control of the optical chopper can be given to the programmable circuit board FPGA for software control and Bluetooth control.

[0062] The high-precision coordination of the actual frequency modulation signal and the reference signal can be ensured through fixed optical path transmission, and the delay difference can also be eliminated through the feedback circuit and software. In addition, different types of chopper blades can be superimposed and used, and can be replaced at any time to achieve different frequency modulation ranges.

[0063] Furthermore, in one or more embodiments of this specification, the fan blades of the optical chopper 7 can be flat fan blades or sloped fan blades. As Figure 4 and Figure 5 shown.

[0064] Figure 4 This is a schematic diagram of the sloped fan blades of a coated film reflective optical chopper in this specification, Figure 5 This is a schematic diagram of the flat fan blades of a coated film reflective optical chopper in this specification, Figure 5 The part marked with diagonal lines in

[0065] The control method of the reflective optical chopper with a coating layer preferably adopts the control methods of wired serial port connection and wireless Bluetooth connection. This method is implemented based on a single-chip microcomputer, FPGA, MCU, including but not limited to a programmable circuit board. This method can minimize the integrated size of the optical frequency modulation of the laser pulse with high-precision co-frequency electrical pulse output and the co-frequency electrical signal output device. There is a fixed optical path delay difference between the output during light transmission and the electrical signal output during light shielding, which can be offset by an internal optical path delay compensation circuit or eliminated by using an external device such as TCSPC during use.

[0066] In addition, in one or more embodiments of this specification, the signal acquisition and conversion circuit 11 may further include a comparator and a Bluetooth module. The comparator compares the real-time frequency of the electrical pulse signal with the preset laser pulse frequency passing through two diaphragms. If it is determined that the fan blade of the optical chopper generates dynamic jitter, the optical chopper is remotely adjusted in real-time dynamically through the Bluetooth module. Through Bluetooth, the wire setting can be eliminated, and the rotation speed of the optical chopper 7 can be remotely adjusted in real-time. Specifically, the rotation speed can be controlled by sending a control signal to the circuit designed for the rotating motor through the Bluetooth module.

[0067] Furthermore, in one or more embodiments of this specification, the signal acquisition and conversion circuit 11 further includes a comparator and an error induction lamp. The comparator compares the real-time frequency of the electrical pulse signal with the preset laser pulse frequency passing through two diaphragms. If it is determined that the rotation speed of the fan blade of the optical chopper deviates from the preset rotation speed and exceeds the preset error range, the error induction lamp lights up to give an alarm. During actual application, if the rotation of the optical chopper 7 accidentally stops or has other accidents, the user can be prompted by the error induction lamp, enabling the user to quickly locate and solve the problem.

[0068] This specification also provides a schematic diagram of using the optical frequency modulation of the laser pulse with high-precision co-frequency electrical pulse output and the co-frequency electrical signal output device for fluorescence lifetime testing, as Figure 6 shown.

[0069] In this example, the beam frequency modulation and electrical signal output principle of the beam in the time-resolved photoluminescence spectroscopy technique can refer to the corresponding description above. The output signal after frequency modulation is used to excite the luminescent material 13 of the target, and the luminescence signal of the material is collected and enters the monochromator 14 to output a beam of a specific wavelength. The output beam selected by wavelength passes through the single-photon detector 15 and is connected to the signal input interface of the TCSPC 16. The reference signal directly passes through the electrical signal output interface 12 of the optical frequency modulation and homodyne electrical signal output device connected to the high-precision homodyne electrical pulse output laser pulse to the reference signal input interface of the TCSPC 16, and then the fluorescence lifetime test of the time-resolved spectroscopy can be carried out. This example only shows a specific example of applying the optical frequency modulation and homodyne electrical signal output device of the high-precision homodyne electrical pulse output laser pulse, and the scope involved includes but is not limited to this example.

[0070] The present invention can realize reliable modulation of the beam repetition frequency and provide a high-precision homodyne output electrical signal. This method can withstand the use conditions of high-intensity pulsed lasers and improve the error between the electrical drive signal and the actual frequency modulation signal. The frequency modulation method can be changed from a manual mode to an intelligent portable means controlled by software and Bluetooth to reduce the space occupation size of the device. The invention can combine with the TCSPC for system tests under the homodyne reference technologies required for time resolution, quantum coherence, and phase locking.

[0071] It should also be noted that the terms "include", "comprise" or any other variant thereof in this specification are intended to cover non-exclusive inclusion, that is, in addition to the elements listed in this specification, other elements not explicitly listed may also be included.

[0072] Each embodiment in this specification is described in a progressive manner. The same or similar parts among the embodiments can be referred to each other, and the key points of each embodiment are the differences from other embodiments.

[0073] The above is only the embodiment of this specification and is not used to limit this specification. For those skilled in the art, various changes and modifications can be made to this specification. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this specification shall be included within the scope of the claims of this specification.

Claims

1. An optical frequency modulation device for laser pulses and a co-frequency electrical signal output device, characterized in that Comprising: Two diaphragms, the laser emitted by the target light source enters the light passing holes of the two diaphragms, and the two diaphragms are used to calibrate and limit the transmission area of the target light source; An optical chopper, arranged between the two diaphragms, and its fan blades are covered with a coating layer. The laser emitted by the target light source is reflected after irradiating the coating layer on the fan blades. By controlling the rotation speed of the optical chopper, the repetition frequency of the laser is adjusted to obtain laser pulses with different frequencies passing through the two diaphragms; An optical sensor, arranged on the reflection path of the laser by the optical chopper, is used to receive the laser pulses obtained by reflection with the same frequency as the laser pulses passing through the two diaphragms and form a photocurrent through the photoelectric effect of the optical sensor; A signal acquisition and conversion circuit, electrically connected to the optical sensor, is used to receive the photocurrent and convert it into an electrical pulse signal with the same frequency as the laser pulses passing through the two diaphragms and then output.

2. The optical frequency modulation of the laser pulse and the output device of the co-frequency electrical signal according to claim 1, characterized in that, The device further includes: a converging optical element, arranged on the reflection optical path of the laser by the coating layer, is used to deflect and focus the laser reflected by the coating layer to form a laser pulse trigger signal with the same frequency as the laser pulses passing through the two diaphragms; The optical sensor, arranged on the deflection path of the laser by the converging optical element, is used to receive the laser pulse trigger signal and form a photocurrent through the photoelectric effect of the optical sensor.

3. The optical frequency modulation of the laser pulse and the output device of the co-frequency electrical signal according to claim 1, characterized in that, The signal acquisition and conversion circuit further includes a comparator and a feedback circuit. The signal acquisition and conversion circuit is also used to perform real-time frequency statistics on the electrical pulse signal, then compare the real-time frequency of the electrical pulse signal with the preset laser pulse frequency passing through the two diaphragms through the comparator, and perform real-time dynamic speed adjustment on the rotation speed of the optical chopper through the feedback circuit.

4. The optical frequency modulation of the laser pulse and the output device of the co-frequency electrical signal according to claim 1, characterized in that, The device further includes: Two reflectors, the two reflectors have three degrees of freedom in the up-down, left-right and pitch directions, and the optical path of the laser emitted by the target light source is adjusted through the two reflectors to make the laser enter the light passing holes of the two diaphragms.

5. The optical frequency modulation of the laser pulse and the output device of the co-frequency electrical signal according to claim 2, characterized in that, The device further includes: An optical breadboard, used to provide a horizontal and stable platform, and the two diaphragms, optical chopper, converging optical element, optical sensor, and signal acquisition and conversion circuit are all installed on the optical breadboard.

6. The optical frequency modulation of the laser pulse and the output device of the co-frequency electrical signal according to claim 1, characterized in that, When the light source band is in the ultraviolet band, the coating layer is an aluminum reflective film; When the light source band is in the visible band, the coating layer is a silver reflective film; When the light source band is in the infrared band, the coating layer is a gold reflective film; When the light source band is greater than the preset spectral band, the coating layer is a dielectric reflective film.

7. The optical frequency modulation of the laser pulse and the output device of the same-frequency electrical signal according to claim 1, characterized in that, The fan blades of the optical chopper are flat fan blades or sloped fan blades.

8. The optical frequency modulation of the laser pulse and the output device of the co-frequency electrical signal according to claim 1, characterized in that, The optical sensor is any one of a photoresistor, a silicon photodetector, or a quantum well sensor.

9. The optical frequency modulation of the laser pulse and the output device of the co-frequency electrical signal according to claim 1, characterized in that, The signal acquisition and conversion circuit further includes a comparator and a Bluetooth module. The real-time frequency of the electrical pulse signal is compared with the preset laser pulse frequency passing through the two diaphragms through the comparator. If it is judged that the fan blades of the optical chopper generate dynamic jitter, the optical chopper is remotely adjusted in real-time dynamically through the Bluetooth module.

10. The optical frequency modulation of a laser pulse and the output device of a co-frequency electrical signal according to claim 1, characterized in that, The signal acquisition and conversion circuit further includes a comparator and an error induction lamp. The comparator compares the real-time frequency of the electrical pulse signal with the preset laser pulse frequency passing through two diaphragms. If it is determined that the rotational speed of the optical chopper fan blade deviates from the preset rotational speed and exceeds the preset error range, the error induction lamp lights up for warning.

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