CN111600196A - Multi-channel low-power-consumption APC control circuit and method for laser forward voltage - Google Patents

Abstract

The invention relates to a multi-channel low-power-consumption APC control circuit and method for laser forward voltage, comprising a multi-channel laser device, an outer ring controller and an inner ring PID controller, wherein the multi-channel laser device is respectively electrically connected with the outer ring controller and the inner ring PID controller, the outer ring controller outputs an initial forward voltage to the multi-channel laser device to ensure that all the lasers work in a locking state, the inner ring PID controller adjusts the first voltage of the lasers by utilizing a PID algorithm according to the sampling voltage fed back by each laser device, simultaneously records and updates the working state of each laser after the inner ring PID controller is debugged and feeds back the working state to the outer ring controller, when all the lasers work in the locking state, the second voltage output by the outer ring controller is reduced by adopting a stepping method until a certain channel or multi-channel laser device cannot work in the locking state, and increasing the second voltage output by the outer ring controller in the same step until all the lasers work again in the locking state.

Description

Multi-channel low-power-consumption APC control circuit and method for laser forward voltage

Technical Field

The invention relates to the technical field of APC control, in particular to a multi-channel low-power-consumption APC control circuit and method for laser forward voltage.

Background

In the conventional APC control of the laser, a power controller is used to output a constant voltage to the laser, so that all the lasers can be operated in a locked state, however, such a method will cause waste of electric energy, and the specific expression is in two aspects: 1) in order to enable the laser to work, a given initial voltage is often larger than the required voltage after working for a period of time, resulting in waste of electric energy; 2) because the characteristics or parameters of each laser are different, the minimum voltage required by the operation of each laser is also different, and the uniform adoption of a constant voltage will certainly cause the waste of electric energy of the lasers with low power consumption.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provide a multi-channel low-power-consumption APC control circuit and method for laser forward voltage.

In order to achieve the above object, the embodiments of the present invention provide the following technical solutions:

a multi-channel low-power-consumption APC control circuit of laser forward voltage comprises a multi-channel laser device, an outer ring controller and an inner ring PID controller, wherein:

the multi-channel laser device is respectively electrically connected with the outer ring controller and the inner ring PID controller, and the working state of the multi-channel laser device is changed according to the adjustment of the outer ring controller and the inner ring PID controller so as to enable the multi-channel laser device to work in a locking state;

the outer ring controller outputs initial forward voltage to the multi-channel laser devices and regulates second voltage output by the multi-channel laser devices according to the working state of each laser device fed back by the inner ring PID controller;

and the inner ring PID controller receives the working state fed back by the multi-channel laser device, adjusts the first voltage output by the multi-channel laser device according to the working state fed back by the multi-channel laser device, and feeds back the working state of the multi-channel laser device to the outer ring controller.

Because the initial forward voltage output by the outer ring controller to the multi-channel laser device is the maximum voltage value which ensures that all lasers in the multi-channel laser device can work in a locking state, but the actual lasers may not need to use the high power consumption, so that the power consumption is wasted, the scheme combines the mutual cooperation of the inner ring PID controller and the outer ring controller, according to the working state fed back by the multi-channel laser device received by the inner ring PID controller, the voltage output to the multi-channel laser device is regulated by the inner ring PID controller and the outer ring controller to form APC closed-loop control, so that the multi-channel laser device can work in a critical locking state, namely, the multi-channel laser device works in a locking state with the lowest power consumption, the voltage output to the multi-channel laser device is regulated by the inner ring and the outer ring together, and the power consumption used when the laser.

Furthermore, in order to describe the composition of the multi-channel laser device in more detail, the multi-channel laser device includes N groups of laser devices, each group of laser device includes an LD laser and a PD light receiver for sensing the LD laser, and the PD light receiver is connected with the inner ring PID controller, and is configured to sense the operating state of the LD laser, and convert the operating state of the LD laser into a voltage signal, and feed the voltage signal back to the inner ring PID controller.

According to the scheme, the PD light receiver is used for sensing the working state of the LD laser, and the working state of the LD laser fed back by the PD light receiver and received by the inner-loop PID controller is the power of the LD laser.

Furthermore, for explaining the composition of the outer ring controller in more detail, the outer ring controller comprises an outer ring DAC controller and a DC-DC controller, and the outer ring DAC controller is electrically connected with the DC-DC controller; the outer ring DAC controller gives an initial forward voltage to the DC-DC controller, and the DC-DC controller simultaneously supplies power to the N groups of laser devices according to the initial forward voltage given by the outer ring DAC controller.

Furthermore, each group of laser devices further comprises a triode, the base electrode of the triode is electrically connected with the inner ring PID controller, the collector electrode of the triode is electrically connected with the DC-DC controller, and the emitter electrode of the triode is electrically connected with the LD laser.

The inner ring PID controller adjusts first voltage output by the LD laser through a base electrode of the triode, namely the first voltage output by the LD laser is the base electrode voltage of the triode, and the DC-DC controller adjusts second voltage output by the LD laser through a collector electrode of the triode, namely the second voltage output by the LD laser is the collector electrode voltage of the triode.

A multi-channel low-power-consumption APC control method for laser forward voltage comprises the following steps:

the outer ring controller outputs initial forward voltage to the multi-channel laser device, so that the multi-channel laser device works in a locking state, and the multi-channel laser device feeds back the working state to the inner ring PID controller;

the inner ring PID controller adjusts the first voltage output by the multi-channel laser device according to the working state fed back by the multi-channel laser device, so that the multi-channel laser device works in a locking state, simultaneously records and updates the working state of the multi-channel laser device, and feeds back the working state to the outer ring controller;

and the outer ring controller regulates the second voltage output by the multi-channel laser device according to the working state of the multi-channel laser device fed back by the inner ring PID controller until the multi-channel laser device works in a critical locking state.

Further, for a more detailed description, the step of the outer-loop controller outputting an initial forward voltage to the multi-channel laser device so that the multi-channel laser device operates in a locked state and the multi-channel laser device feeds back the operating state to the inner-loop PID controller includes:

an outer ring DAC controller in the outer ring controller gives an initial forward voltage of the DC-DC controller;

the DC-DC controller outputs voltage to the N groups of laser devices according to the initial forward voltage given by the outer ring DAC controller, so that all LD lasers in the N groups of laser devices work in a locking state;

the PD light receivers corresponding to each LD laser in the N groups of laser devices sense the working state of the LD lasers, convert the working state of the LD lasers into voltage signals and feed the voltage signals back to the inner ring PID controller.

Furthermore, the LD laser operates in a locked state, which means that the output power of the LD laser operates within a set value range;

the PD light receiver senses the working state of the LD laser, converts the working state of the laser into a voltage signal and feeds the voltage signal back to the PID controller, namely the PD light receiver senses laser emitted by the LD laser, converts the sensed laser into the voltage signal and feeds the voltage signal back to the inner ring PID controller; the voltage signal represents the power of the LD laser.

Further, to explain the working state fed back by the multi-channel laser device by the inner loop PID controller in more detail, the step of adjusting the first voltage output by the multi-channel laser device according to the working state fed back by the multi-channel laser device, so that the multi-channel laser device works in a locked state, and simultaneously recording and updating the working state of the multi-channel laser device, and feeding back the working state to the outer loop controller, includes:

the inner ring PID controller performs PID calculation according to the voltage signal fed back by each PD light receiver, and respectively adjusts the first voltage output to each LD laser according to the calculation result, so that each LD laser works in a locking state; and the inner ring PID controller records and updates the working state of each LD laser device and feeds the working state back to the outer ring controller.

Further, for more detailed description, the step of the outer-loop controller adjusting the second voltage output by the multi-channel laser device according to the operating state of the multi-channel laser device fed back by the inner-loop PID controller until the multi-channel laser device operates in the critical locking state includes:

the outer ring DAC controller of the outer ring controller increases DAC signals output to the DC-DC controller according to the working state of the laser device fed back by the inner ring PID controller, so that the DC-DC controller reduces second voltage output to all LD lasers, and the increase of the DAC signals output to the DC-DC controller is stopped until a certain LD laser does not work in a locking state;

and the outer ring DAC controller reversely reduces the DAC signal output to the DC-DC controller, so that the DC-DC controller increases the second voltage output to all the LD lasers until all the LD lasers recover to work in the locking state, and stops reducing the DAC signal output to the DC-DC controller, so that all the LD lasers work in the critical locking state.

Compared with the prior art, the invention has the beneficial effects that:

(1) the invention uses the inner ring PID controller and the outer ring controller to control in a mutually matched way, and regulates the voltage output to the LD laser, so that the multi-channel LD laser works in a locking state with the lowest power consumption, and the power consumption of the LD laser is reduced.

(2) The invention uses the PD light receiver to sense the laser emitted by the LD laser, then converts the sensed laser into a voltage signal and feeds the voltage signal back to the inner ring PID controller, the inner ring PID controller calculates the PID algorithm according to the current power of the LD laser to obtain a strategy for adjusting the output voltage of the LD laser, and the adjusting force can be quickly and accurately calculated by combining the PID algorithm.

(3) The invention uses the PID controller to calculate the working state of the laser fed back by the PD light receiver to obtain the adjusting strategy, then adjusts the voltage output by the laser, simultaneously records and updates the working state of each laser debugged by the inner ring PID controller, and feeds back the working state to the outer ring controller.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

FIG. 1 is a schematic diagram of an APC control circuit according to an embodiment of the present invention;

FIG. 2 is a schematic circuit diagram of an outer-loop controller in an APC controller circuit according to an embodiment of the present invention (partially enlarged in FIG. 1);

FIG. 3 is a schematic circuit diagram (partially enlarged in FIG. 1) of any one group of laser devices in the APC controller circuit according to the embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

Example 1:

the invention is realized by the following technical scheme, a multi-channel low-power consumption APC control circuit of laser forward voltage comprises a multi-channel laser device, an outer ring controller and an inner ring PID controller, wherein:

as shown in fig. 1, the multichannel laser device includes N groups of laser devices, and as shown in fig. 3, each group of laser devices includes an LD laser, a PD light receiver for sensing the LD laser, and a triode, and the PD light receiver is connected to the inner ring PID controller, and is configured to sense a working state of the LD laser, and convert the working state of the LD laser into a voltage signal, and feed the voltage signal back to the inner ring PID controller.

The base electrode of the triode is electrically connected with the inner ring PID controller, the collector electrode of the triode is electrically connected with the outer ring controller, the emitter electrode of the triode is connected with the LD light receiver, namely the inner ring PID controller adjusts the first voltage output to the LD laser through the base electrode of the triode, the outer ring controller adjusts the second voltage output to the LD laser through the collector electrode of the triode, the base electrode voltage of the triode is the first voltage, and the collector electrode voltage of the triode is the second voltage.

It should be noted that the PD light receiver senses the operating state of the LD laser including an operating state in which the output power of the LD laser is within a set value range and an operating state in which the LD laser is not operating; the non-operation in the locked state means that the output power of the LD laser is not operated within a set value range. After the PD light receiver senses the laser emitted by the LD laser, the laser is converted into a voltage signal, the inner ring PID controller can calculate the power of the LD laser according to a PID algorithm according to a sampling voltage signal fed back by the PD light receiver, and judges whether the LD laser works in a locking state or not.

As shown in fig. 2, the outer-loop controller includes an outer-loop DAC controller and a DC-DC controller, the outer-loop DAC controller gives an initial forward voltage to the DC-DC controller, and the DC-DC controller outputs the initial forward voltage to each LD laser to power the LD lasers, so that each LD laser operates in a locked state, and thus the initial forward voltage is a maximum voltage value that can ensure that all LD lasers operate in the locked state. However, it may not be necessary to use such high power consumption for the actual LD laser, and even the power consumption of the individual LD laser may be lower due to the characteristics or parameters of the individual LD laser, so that in this case, it is necessary to continuously reduce the voltage output to each LD laser by matching the inner ring and the outer ring, so that each LD laser operates in the critical locking state, and at this time, the power consumption used by each LD laser is the lowest, which will be described in detail in this embodiment.

The input end of the inner ring PID controller is connected to all PD light receivers in the multi-channel laser device to receive the working state of the LD laser device fed back by the PD light receivers, the output end of the inner ring PID controller is connected to the base electrode of a triode in the multi-channel laser device, and the first voltage output by each LD laser device is adjusted through the base electrode of the triode. Since the initial forward voltage of the LD laser operation is the maximum voltage value, the inner loop PID controller adjusts the first voltage output by the LD laser to reduce the first voltage output. When the first voltage output to the LD lasers is reduced, it is still necessary to ensure that all the LD lasers operate in the locked state.

It should be noted that the working states fed back to the inner-loop PID controllers by the PD light receivers are basically different, so that the inner-loop PID controllers need to perform PID calculation on the received working states respectively to obtain a strategy for reducing the first voltage output by each LD laser, and at this time, the voltage reduction forces of the inner-loop PID controllers on the LD lasers are different, and at this time, the voltage values at the two ends of each LD laser are no longer the same.

After the adjustment of the inner ring PID controller, all LD lasers still work in a locking state, and then the inner ring PID controller feeds back the working state of each LD laser after debugging the LD lasers to the outer ring controller, wherein the debugging of each LD laser is to reduce the first voltage output to each LD laser respectively. And an outer ring DAC controller in the outer ring controller receives the regulation state fed back by the inner ring PID controller, and regulates the second voltage output by the LD laser according to the regulation state, so that the multi-channel laser device works in a critical locking state.

When the outer ring controller regulates the second voltage output by the LD laser, firstly, the outer ring DAC controller increases the DAC signal output by the DC-DC controller by a stepping method, so that the DC-DC controller reduces the second voltage output by all the LD lasers, and the increase of the DAC signal output by the DC-DC controller is stopped until the LD laser does not work in a locking state; and then the outer ring DAC controller reduces the DAC signal output to the DC-DC controller again by using the same step and reverse direction, so that the DC-DC controller increases the second voltage output to all the LD lasers until all the LD lasers recover to work in a locking state, and stops reducing the DAC signal output to the DC-DC controller, so that all the LD lasers work in a critical state.

At the moment, all LD lasers can work in a locking state with the lowest power consumption, and the aim of reducing the working power consumption of the lasers is achieved after the inner ring and the outer ring are adjusted.

The invention collects and regulates the voltage output by the LD laser through the mutual matching control of the outer ring controller and the inner ring PID controller, and ensures that all LD lasers can work in a locking state with the lowest power consumption through the regulation mode of APC automatic power, thereby reducing the working power consumption of the lasers.

Based on the APC control circuit, the invention also provides a multichannel low-power-consumption APC control method for the forward voltage of the laser, which comprises the following steps:

step S100: the outer ring controller outputs initial forward voltage to the multi-channel laser device, so that the multi-channel laser device works in a locking state, and the multi-channel laser device feeds back the working state to the inner ring PID controller.

An outer ring DAC controller in the outer ring controller gives an initial forward voltage of the DC-DC controller; the DC-DC controller outputs voltage to the N groups of laser devices according to initial forward voltage given by the outer ring DAC controller, so that all LD lasers in the N groups of laser devices work in a locked state, and the initial forward voltage is the maximum voltage value used by the LD lasers; the PD light receivers corresponding to each LD laser in the N groups of laser devices sense the working state of the LD lasers, convert the working state of the LD lasers into voltage signals and feed the voltage signals back to the inner ring PID controller.

The working state of the LD laser is in a locking state, namely the output power of the LD laser is in a set value range, the PD light receiver senses the working state of the LD laser and converts the working state of the laser into a voltage signal to feed back to the PID controller, and the PD light receiver senses laser emitted by the LD laser, converts the sensed laser into the voltage signal and feeds back the voltage signal to the PID controller; the voltage signal represents the power of the LD laser.

Step S200: and the inner ring PID controller regulates the first voltage output by the multi-channel laser device according to the working state fed back by the multi-channel laser device, so that the multi-channel laser device works in a locking state, simultaneously records and updates the working state of the multi-channel laser device, and feeds back the working state to the outer ring controller.

And the inner ring PID controller performs PID calculation according to the voltage signal fed back by each PD light receiver, and respectively reduces the first voltage output to each LD laser according to the calculation result, so that each LD laser can still work in a locking state. It should be noted that, the inner-loop PID controller respectively adjusts the first voltage output by each LD laser, so the reduced strength of the first voltage of each LD laser may be different, but it is still ensured that all LD lasers operate in a locked state after the first voltage is reduced. Then the inner ring PID controller records and updates the working state of each LD laser device and feeds the working state back to the outer ring controller.

Step S300: and the outer ring controller regulates the second voltage output by the multi-channel laser device according to the working state of the multi-channel laser device fed back by the inner ring PID controller until the multi-channel laser device works in a critical locking state.

The outer ring DAC controller of the outer ring controller increases DAC signals output to the DC-DC controller by using a stepping method according to the working state of the LD laser fed back by the inner ring PID controller, so that the DC-DC controller reduces second voltage output to all the LD lasers, and the increase of the DAC signals output to the DC-DC controller is stopped until a certain LD laser does not work in a locking state; and then the outer ring DAC controller reduces the DAC signal output to the DC-DC controller by using the same step reverse direction, so that the DC-DC controller increases the second voltage output to all the LD lasers until all the LD lasers recover to work in the locking state, and stops reducing the DAC signal output to the DC-DC controller, so that all the LD lasers work in the critical locking state.

Example 2:

as another possible implementation manner, since the initial forward voltage output to the LD laser may be an empirical voltage value used by the LD laser history, there is a possibility that the initial forward voltage cannot guarantee that all the LD lasers are working in the locked state, that is, after the initial forward voltage is output, the LD lasers still cannot work in the locked state, at this time, after the inner loop PID controller performs PID calculation through the voltage signal fed back by the PD light receiver, the first voltage output to the LD lasers needs to be increased so that all the LD lasers can work in the locked state, then the outer loop controller adjusts the second voltage output by the LD lasers again according to the working state of the LD lasers fed back by the inner loop PID controller so that all the LD lasers work in the critical locked state, and the manner that the outer loop controller adjusts the second voltage output by the LD lasers is the same as that in embodiment 1, therefore, it will not be described herein.

In this embodiment, there is another situation that after the initial forward voltage is output, the LD laser still cannot operate in the locked state, at this time, the inner loop PID controller increases the first voltage output to the LD laser, and when the first voltage value is increased to the maximum value, it is still not guaranteed that all the LD lasers operate in the locked state, so at this time, the outer loop controller is required to increase the second voltage output to the LD laser, so that all the LD lasers can operate in the locked state. And then the outer ring controller regulates the second voltage output by the LD laser, and finally all the LD lasers work in a critical locking state.

In summary, when the voltage output by the LD laser is adjusted, the present invention needs to perform PID calculation according to the actual characteristics or parameters of the LD laser, and then adjusts the voltage, which may reduce the first voltage/second voltage output by the LD laser, and may increase the first voltage/second voltage output by the LD laser.

The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims (9)

1. A multi-channel low-power-consumption APC control circuit of laser forward voltage is characterized in that: the device comprises a multi-channel laser device, an outer ring controller and an inner ring PID controller, wherein:

the multi-channel laser device is respectively electrically connected with the outer ring controller and the inner ring PID controller, and the working state of the multi-channel laser device is changed according to the adjustment of the outer ring controller and the inner ring PID controller so as to enable the multi-channel laser device to work in a locking state;

the outer ring controller outputs initial forward voltage to the multi-channel laser devices and regulates second voltage output by the multi-channel laser devices according to the working state of each laser device fed back by the inner ring PID controller;

and the inner ring PID controller receives the working state fed back by the multi-channel laser device, adjusts the first voltage output by the multi-channel laser device according to the working state fed back by the multi-channel laser device, and feeds back the working state of the multi-channel laser device to the outer ring controller.

2. The circuit of claim 1, wherein: the multichannel laser device comprises N groups of laser devices, each group of laser devices comprises an LD laser and a PD light receiver for sensing the LD laser, and the PD light receiver is connected with the inner ring PID controller and used for sensing the working state of the LD laser and converting the working state of the LD laser into a voltage signal to be fed back to the inner ring PID controller.

3. The circuit of claim 2, wherein: the outer ring controller comprises an outer ring DAC controller and a DC-DC controller, and the outer ring DAC controller is electrically connected with the DC-DC controller; the outer ring DAC controller gives an initial forward voltage to the DC-DC controller, and the DC-DC controller simultaneously supplies power to the N groups of laser devices according to the initial forward voltage given by the outer ring DAC controller.

4. The circuit of claim 3, wherein: each group of laser devices further comprises a triode, the base electrode of the triode is electrically connected with the inner ring PID controller, the collector electrode of the triode is electrically connected with the DC-DC controller, and the emitter electrode of the triode is electrically connected with the LD laser.

5. A multi-channel low-power-consumption APC control method of laser forward voltage is characterized in that: the method comprises the following steps:

the outer ring controller outputs initial forward voltage to the multi-channel laser device, so that the multi-channel laser device works in a locking state, and the multi-channel laser device feeds back the working state to the inner ring PID controller;

the inner ring PID controller adjusts the first voltage output by the multi-channel laser device according to the working state fed back by the multi-channel laser device, so that the multi-channel laser device works in a locking state, simultaneously records and updates the working state of the multi-channel laser device, and feeds back the working state to the outer ring controller;

and the outer ring controller regulates the second voltage output by the multi-channel laser device according to the working state of the multi-channel laser device fed back by the inner ring PID controller until the multi-channel laser device works in a critical locking state.

6. The method of claim 5, wherein: the outer ring controller outputs initial forward voltage to the multichannel laser device, so that the multichannel laser device works in a locking state, and the multichannel laser device feeds back the working state to the inner ring PID controller, and the method comprises the following steps:

an outer ring DAC controller in the outer ring controller gives an initial forward voltage of the DC-DC controller;

the DC-DC controller outputs voltage to the N groups of laser devices according to the initial forward voltage given by the outer ring DAC controller, so that all LD lasers in the N groups of laser devices work in a locking state;

the PD light receivers corresponding to each LD laser in the N groups of laser devices sense the working state of the LD lasers, convert the working state of the LD lasers into voltage signals and feed the voltage signals back to the inner ring PID controller.

7. The method of claim 6, wherein: the LD laser works in a locking state, which means that the output power of the LD laser works in a set value range;

the PD light receiver senses the working state of the LD laser, converts the working state of the laser into a voltage signal and feeds the voltage signal back to the PID controller, namely the PD light receiver senses laser emitted by the LD laser, converts the sensed laser into the voltage signal and feeds the voltage signal back to the inner ring PID controller; the voltage signal represents the power of the LD laser.

8. The method of claim 7, wherein: the inner ring PID controller adjusts the first voltage output by the multi-channel laser device according to the working state fed back by the multi-channel laser device, so that the multi-channel laser device works in a locking state, simultaneously records and updates the working state of the multi-channel laser device, and feeds back the working state to the outer ring controller, and the inner ring PID controller comprises the following steps:

the inner ring PID controller performs PID calculation according to the voltage signal fed back by each PD light receiver, and respectively adjusts the first voltage output to each LD laser according to the calculation result, so that each LD laser works in a locking state;

the inner ring PID controller records and updates the working state of each LD laser device and feeds the working state back to the outer ring controller.

9. The method of claim 8, wherein: the outer ring controller regulates the second voltage output by the multi-channel laser device according to the working state of the multi-channel laser device fed back by the inner ring PID controller until the multi-channel laser device works in a critical locking state, and the method comprises the following steps:

the outer ring DAC controller of the outer ring controller increases DAC signals output to the DC-DC controller according to the working state of the LD laser fed back by the inner ring PID controller, so that the DC-DC controller reduces second voltage output to all the LD lasers, and the increase of the DAC signals output to the DC-DC controller is stopped until a certain LD laser does not work in a locking state;

and the outer ring DAC controller reversely reduces the DAC signal output to the DC-DC controller, so that the DC-DC controller increases the second voltage output to all the LD lasers until all the LD lasers recover to work in the locking state, and stops reducing the DAC signal output to the DC-DC controller, so that all the LD lasers work in the critical locking state.

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