Acousto-optic modulator driving system with servo feedback

Abstract

The invention discloses an acousto-optic modulator driving system with servo feedback. The system comprises a radio frequency generation module, a power control module, a radio frequency switch module, a power display module, a power amplification module, a sensor module and a servo feedback module. The radio frequency generation module generates a radio frequency signal and sends the radio frequency signal to the power control module; the power control module adjusts the attenuation degree of the radio frequency signal and then sends the radio frequency signal to the radio frequency switch module; the radio frequency switch module controls a radio frequency signal to enter the power amplification module or the power display module; the power display module displays the radio frequency power actually output by the power amplification module; the power amplification module amplifies the radio frequency signal and then outputs the radio frequency signal to the acousto-optic crystal; the sensor module receives the laser output by the acousto-optic crystal and outputs a photovoltage signal to the servo feedback module; the servo feedback module receives the photovoltage signal, compares the photovoltage signal with a preset value and then outputs a feedback control signal. The method can be used for optical power control and can also be used for light beam space stability control.

Description

Technical Field

[0001] The present application belongs to the field of laser control technology, and in particular relates to an acousto-optic modulator driving system with servo feedback. Background Art

[0002] In the process of using lasers, acousto-optic modulators based on the acousto-optic effect are widely used. They can be used to accurately control the frequency, switch and intensity of the laser, as well as the deflection angle of the laser. When the acousto-optic modulator works, it needs a radio frequency source to drive it. It is by controlling the frequency, intensity and switch of the radio frequency source that the frequency, intensity, switch and deflection angle of the laser after passing through the acousto-optic modulator are controlled.

[0003] However, existing drivers cannot flexibly control lasers. In addition, during the use of lasers, the instability of the input laser power, RF frequency or mechanical structure often leads to instability in the optical power output from the AOM and instability in the spatial position. The most serious problem is the thermal effect of the AOM. Under fixed RF power and frequency, the deflection angle of the light beam will shift to a certain extent with the temperature of the AOM crystal, which seriously affects the spatial stability of the laser. Summary of the invention

[0004] The purpose of this application is to overcome the defects of the prior art and provide an acousto-optic modulator driving system with servo feedback, aiming to improve the flexibility and stability of laser control.

[0005] The purpose of this application is achieved through the following technical solutions:

[0006] An acousto-optic modulator driving system with servo feedback, the system comprising:

[0007] A radio frequency generation module, wherein the radio frequency generation module generates a radio frequency signal and sends the signal to the power control module;

[0008] A power control module, wherein the power control module adjusts the attenuation of the radio frequency signal and then sends it to the radio frequency switch module;

[0009] A radio frequency switch module, which controls the radio frequency signal to enter the power amplifier module or the power display module;

[0010] A power display module, which displays the actual output RF power of the power amplifier module after the corresponding relationship between the power injected by the RF switch module and the output power of the subsequent power amplifier module is calibrated;

[0011] A power amplifier module, which amplifies the radio frequency signal and outputs it to the acousto-optic crystal;

[0012] A sensor module, the sensor module receives the laser output by the acousto-optic crystal and outputs a photovoltage signal to a servo feedback module;

[0013] A servo feedback module receives the photovoltage signal, compares the photovoltage signal with a preset value, and then outputs a feedback control signal.

[0014] Further, the sensor module includes a PD detector;

[0015] After receiving the photovoltage signal output by the PD detector, the servo feedback module outputs a feedback control signal to the power control module to dynamically control the intensity of the radio frequency signal.

[0016] Furthermore, the first-order diffraction light generated by the acousto-optic crystal passes through a reflector and then a focusing lens and enters the PD detector.

[0017] Further, the sensor module includes a four-quadrant detector;

[0018] After receiving the photovoltage signal output by the four-image detector, the servo feedback module outputs a feedback control signal to the radio frequency generation module to dynamically control the frequency of the radio frequency signal.

[0019] Furthermore, the first-order diffraction light generated by the acousto-optic crystal passes through a reflector, passes through a beam expander lens group, and then enters a four-quadrant detector.

[0020] Furthermore, the driving system also includes a frequency display module, and the radio frequency generation module inputs the radio frequency signal to the frequency display module, and the frequency display module displays the current radio frequency.

[0021] Furthermore, the power control switch comprises a single-pole triple-throw switch, which is controlled by a manual control switch, a remote control switch and a servo feedback signal respectively.

[0022] Furthermore, the radio frequency generation module includes a single-pole triple-throw switch, which is controlled by a manual control switch, a remote control switch and a servo feedback signal respectively.

[0023] Furthermore, the radio frequency switch module includes a single-pole double-throw switch, which is controlled by a manual control switch and a remote control switch respectively.

[0024] Furthermore, the driving system includes a dual-path servo feedback module, and the two-path servo feedback modules respectively feed back feedback signal control in the X direction and the Y direction to the RF generating module.

[0025] The beneficial effects of this application are:

[0026] (1) The driving system proposed in this application can simultaneously realize the control of the frequency, switch and intensity of the laser. The RF driving system can also display the current frequency and intensity in real time, and the system realizes stable output of the laser through the servo feedback function.

[0027] (2) The driving system proposed in this application can realize the control of the frequency, switch and intensity of the laser and can freely switch between manual control and program control. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a schematic diagram of an acousto-optic modulator driving system with servo feedback according to an embodiment of the present application;

[0029] Figure 2 This is a schematic diagram of optical power feedback control in an embodiment of the present application;

[0030] Figure 3 This is a schematic diagram of the unidirectional position stability feedback control of the light beam in an embodiment of the present application. DETAILED DESCRIPTION

[0031] The following describes the embodiments of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. The present application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0032] Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of this application.

[0033] Existing drivers cannot flexibly control lasers. In addition, during the use of lasers, the instability of the input laser power, RF frequency or mechanical structure often leads to instability in the optical power output from the AOM and instability in the spatial position. The most serious problem is the thermal effect of the AOM. Under fixed RF power and frequency, the deflection angle of the light beam will shift to a certain extent with the temperature of the AOM crystal, which seriously affects the spatial stability of the laser.

[0034] In order to solve the above technical problems, the following embodiments of an acousto-optic modulator driving system with servo feedback are proposed in the present application.

[0035] Reference Figure 1 ,like Figure 1 FIG. 1 is a schematic diagram of an acousto-optic modulator driving system with servo feedback according to an embodiment of the present application. The principle of the system is as follows:

[0036] The RF generation module generates RF signals. The frequency is controlled by a manual adjustment panel knob, an external analog voltage signal or a position servo feedback control signal through a single-pole triple-throw switch. The three signals can be switched freely. By inputting a small part of the RF signal of the module into the frequency display module, the current RF frequency can be displayed in real time on the LCD panel of the module.

[0037] The RF signal is output from the RF generation module and enters the power control module. The control module controls the power by controlling the attenuation of the RF signal. The control voltage is also provided by a single-pole three-throw switch, which is manually adjusted by the panel knob, the external analog voltage or the power servo feedback signal. The three signals can be switched freely. The RF signal is output from the power control module and enters the RF switch module.

[0038] The switching signal of the RF switch module is provided by a manual switch on the panel or a remote digital signal through a single-pole double-throw switch. The two can be switched freely. The RF switch is a single-pole double-throw switch. When the control signal is high, the RF signal enters channel 1, and when the control signal is low, the RF signal enters channel 2.

[0039] When the control signal is at a high level, the RF signal enters the power amplifier module and is amplified and then output. When the control signal is at a low level, the RF signal is injected into the power display module.

[0040] The power display module displays the actual RF power output by the power amplifier module after the corresponding relationship between the power injected by the RF switch and the output power of the subsequent power amplifier module is calibrated.

[0041] The RF signal output by the RF power amplifier is injected into the acousto-optic crystal to control the parameters of the laser passing through the acousto-optic crystal, including the frequency of the light, the optical power, the switch, and the deflection angle of the light beam. By connecting the signal of the optical power sensor or the position sensor to the feedback module based on the PID algorithm, the system also has the servo feedback control function of the laser power and the deflection angle of the light beam. These two functions can be switched freely through a single-pole double-throw switch. The control principles of the two servo feedbacks are as follows:

[0042] The first is the optical power feedback control function, refer to Figure 2 ,like Figure 2 Shown is a schematic diagram of optical power feedback control according to an embodiment of the present application.

[0043] After the RF signal is output from the RF power amplifier, it is connected to the acousto-optic modulation crystal. After the laser passes through the acousto-optic modulation crystal, it generates first-order diffraction light, and the zero-order light enters the laser collector. The first-order diffraction light passes through the reflector, and most of the laser is reflected for subsequent use. A very small part of the laser passes through the reflector and enters the PD detector through the focusing lens and is converted into a voltage signal. The voltage signal output by the PD detector is connected to the servo feedback module as a feedback signal. The servo feedback module subtracts it from the set value to obtain an error signal. The error signal is output after passing through the PID circuit. The output signal passes through the single-pole double-throw switch and is connected to the power control module. The power of the laser is controlled by dynamically controlling the intensity of the RF signal to stabilize the output laser at the set power value.

[0044] The second is the unidirectional position stability of the beam, refer to Figure 3 ,like Figure 3 Shown is a schematic diagram of the unidirectional position stability feedback control of the light beam in an embodiment of the present application.

[0045] After the RF signal is output from the RF power amplifier, it is connected to the acousto-optic modulation crystal. After the laser passes through the acousto-optic modulation crystal, it generates first-order diffraction light, and the zero-order light enters the laser collector. The deflection angle of the first-order diffraction light is related to the input RF frequency. The first-order diffraction light passes through the reflector, and most of the laser is reflected for use by the subsequent system. A very small part of the laser passes through the reflector and first passes through the two lenses to form a telescope system to expand the light beam, and then enters the four-quadrant detector to be converted into a voltage signal. The voltage signal output by the four-quadrant detector is connected to the servo feedback module as a feedback signal. The servo feedback module subtracts it from the set value to obtain an error signal. The error signal is output after passing through the PID circuit. The output signal passes through the single-pole double-throw switch and is connected to the frequency control module. The deflection angle of the first-order diffraction light laser is controlled by dynamically controlling the frequency of the RF signal to make it stably point to the set position.

[0046] In order to achieve the stability of the beam in space, it is necessary to control the stability of the deflection angles in two mutually perpendicular directions. Therefore, a dual-channel servo drive can be used to stabilize the position in the X and Y directions respectively.

[0047] The acousto-optic modulator driving system with servo feedback provided in this embodiment is fully functional and can simultaneously realize the control of the frequency, switch and intensity of the laser. The system can realize free switching between manual control and program control. The system can display the current frequency and intensity in real time, which is convenient for parameter adjustment. The system has a servo feedback function. The feedback module can be used for feedback control of optical power and feedback control of spatial stability of the light beam. The function can be freely switched between the two, and the application scenarios are more extensive.

[0048] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. An acousto-optic modulator driving system with servo feedback, characterized in that: The system comprises: A radio frequency generation module, wherein the radio frequency generation module generates a radio frequency signal and sends the signal to the power control module; A power control module, wherein the power control module adjusts the attenuation of the radio frequency signal and then sends it to the radio frequency switch module; A radio frequency switch module, which controls the radio frequency signal to enter the power amplifier module or the power display module; A power display module, which displays the actual output RF power of the power amplifier module after the corresponding relationship between the power injected by the RF switch module and the output power of the subsequent power amplifier module is calibrated; A power amplifier module, which amplifies the radio frequency signal and outputs it to the acousto-optic crystal; A sensor module, the sensor module receives the laser output by the acousto-optic crystal and outputs a photovoltage signal to a servo feedback module; A servo feedback module receives the photovoltage signal, compares the photovoltage signal with a preset value, and then outputs a feedback control signal.

2. The AOM driving system with servo feedback as claimed in claim 1, characterized in that: The sensor module includes a PD detector; After receiving the photovoltage signal output by the PD detector, the servo feedback module outputs a feedback control signal to the power control module to dynamically control the intensity of the radio frequency signal.

3. The AOM driving system with servo feedback as claimed in claim 2, characterized in that: The first-order diffraction light generated by the acousto-optic crystal passes through a reflector and then a focusing lens and enters the PD detector.

4. The AOM driving system with servo feedback as claimed in claim 1, characterized in that: The sensor module includes a four-quadrant detector; After receiving the photovoltage signal output by the four-image detector, the servo feedback module outputs a feedback control signal to the radio frequency generation module to dynamically control the frequency of the radio frequency signal.

5. The AOM driving system with servo feedback as claimed in claim 4, characterized in that: The first-order diffraction light generated by the acousto-optic crystal passes through a reflector, and then passes through a beam expansion lens group and enters a four-quadrant detector.

6. The AOM driving system with servo feedback as claimed in claim 1, characterized in that: The driving system further comprises a frequency display module. The radio frequency generating module inputs the radio frequency signal into the frequency display module, and the frequency display module displays the current radio frequency.

7. The AOM driving system with servo feedback as claimed in claim 2, characterized in that: The power control switch comprises a single-pole triple-throw switch, which is controlled by a manual control switch, a remote control switch and a servo feedback signal respectively.

8. The AOM driving system with servo feedback as claimed in claim 4, characterized in that: The radio frequency generation module comprises a single-pole triple-throw switch, which is controlled by a manual control switch, a remote control switch and a servo feedback signal respectively.

9. The AOM driving system with servo feedback as claimed in claim 1, characterized in that: The radio frequency switch module includes a single-pole double-throw switch, which is controlled by a manual control switch and a remote control switch respectively.

10. The AOM driving system with servo feedback as claimed in claim 4, characterized in that: The driving system includes a dual-path servo feedback module, and the two-path servo feedback modules respectively feed back feedback signal control in the X direction and the Y direction to the radio frequency generating module.

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