CN106300008B

CN106300008B - Method for regulating and controlling output frequency of laser

Info

Publication number: CN106300008B
Application number: CN201610769696.3A
Authority: CN
Inventors: 陈然
Original assignee: Beijing Grace Laser Technology Co ltd
Current assignee: Beijing Grace Laser Technology Co ltd
Priority date: 2016-08-30
Filing date: 2016-08-30
Publication date: 2020-04-28
Anticipated expiration: 2036-08-30
Also published as: CN106300008A

Abstract

The invention discloses a method for regulating and controlling the output frequency of a laser, which comprises the following steps: (1) when the laser starts to work, the time sequence control module provides N paths of trigger signals, the trigger signals are divided into two types, one type is a signal generated by controlling the laser, namely an A-type signal; the other is other control signals, i.e. class B signals; (2) the frequency of the A-type signal and the B-type signal received by the laser internal module is unchanged, and the delay time of the A-type signal and the B-type signal is changed, so that the output frequency of the laser is changed. The regulation and control method of the invention utilizes the time sequence control mode of the laser system to regulate the output frequency of the laser, the working frequency of the internal module of the laser is kept unchanged, the heat effect of the internal module of the laser is kept unchanged, and the stability of the laser output parameters is improved. Meanwhile, the method can control the time point of the laser output pulse and the number of the output pulses at will, and is simple and convenient to operate and easy to realize.

Description

Method for regulating and controlling output frequency of laser

Technical Field

The invention belongs to the technical field of laser, and particularly relates to a method for regulating and controlling the output frequency of a laser.

Background

The laser output frequency of a pulsed laser is one of its important parameters. In many practical applications, a function of adjusting the repetition frequency of the laser output is often required, and even a function of arbitrarily controlling the time point of the laser output pulse and the number of output pulses is required. For example: for laser medical cosmetic devices, the output frequency of the laser output laser is usually required to be adjustable between 1Hz and 10Hz, depending on the treatment method. For the above application requirements, in order to achieve the purpose of adjusting the output frequency, there are two common methods:

(1) the aim of adjusting the repetition frequency of the output laser is achieved by changing the overall working frequency of the laser system. When the laser works, two or more paths of time sequence signals are usually needed, and each path of time sequence signal controls different devices or modules, so that the laser is finally output at a set repetition frequency. The method for changing the overall working frequency of the laser system is to change the repetition frequency of all time sequence signals, so as to achieve the purpose of adjusting the repetition frequency of the output laser. Taking a commercially available lamp-pumped nanosecond medical cosmetic laser as an example, some lasers employ a repetition rate modulation method as follows: the repetition frequencies of the Q-switched time sequence signal of the laser and the lamp pump time sequence signal are kept consistent, and the aim of adjusting the repetition frequency of the output laser is achieved by simultaneously changing the repetition frequency of the two paths of time sequence signals. The method is simple and easy to operate, and has relatively simple requirements on a control system, but because the change of the overall working frequency of the laser can affect laser parameters such as laser divergence angle, beam quality and the like, other parameter indexes of the laser can also be changed while the laser output frequency is changed by the method, which is the defect of the method.

(2) The frequency division working mode is as follows: the working principle is that the time sequence control signal of the laser system is divided into two types, one is a signal generated by controlling laser, and the signal is called as A-type signal for short; the other is other control signals, hereinafter referred to as class B signals. The frequency division work is to divide the A-type signal and the B-type signal into different repetition frequencies, the repetition frequency of the A-type signal is consistent with the laser output frequency, the repetition frequency of the B-type signal keeps a fixed value and is irrelevant to the laser output frequency, and the purpose of adjusting the repetition frequency of the output laser is realized by changing the repetition frequency of the A-type signal. Taking a commercially available lamp-pumped picosecond medical cosmetic laser as an example, some lasers employ a repetition rate modulation method as follows: the timing control signal of the seed source laser is separated from the timing control signal of the lamp pump amplifier. The time sequence control signal of the seed source is an A-type signal, the time sequence control signal of the lamp pump amplifier is a B-type signal, when the output repetition frequency of the laser is adjusted, only the repetition frequency of the seed source is changed, the working repetition frequency of the lamp pump amplifier is kept unchanged, and the repetition frequency of the finally output laser is the same as the repetition frequency of the seed source and is irrelevant to the repetition frequency of the lamp pump amplifier. The working frequency of the device and the module controlled by the B-type signal in the frequency division modulation method is fixed, so that the influence of the device and the module on the output laser parameters in the process of changing the laser repetition frequency is effectively avoided. However, since the repetition frequency of the devices and modules controlled by the class a signal still varies with the laser output frequency, the influence on the laser output parameters still remains.

The two methods change the laser output frequency and the working frequency of devices and modules in the laser, so that the thermal effect of the laser is changed when the laser works at different repetition frequencies, and the stability of laser output parameters is influenced.

Disclosure of Invention

In order to overcome the defects of the method for adjusting the output frequency of the laser in the prior art, the invention provides a method for adjusting and controlling the output frequency of the laser.

The invention relates to a method for regulating and controlling the output frequency of a laser, which comprises the following steps:

(1) when the laser starts to work, the time sequence control module provides N paths of trigger signals, the trigger signals are divided into two types, one type is a signal generated by controlling the laser, namely an A-type signal; the other is other control signals, i.e. class B signals;

(2) the frequency of the A-type signal and the B-type signal received by the laser internal module is unchanged, and the delay time of the A-type signal and the B-type signal is changed, so that the output frequency of the laser is changed.

Further, class a signals include, but are not limited to: the laser device comprises a laser device Q-switching signal, a seed source trigger signal, a clipping trigger signal and a trigger signal of a preceding laser device in a large laser system.

Further, class B signals include, but are not limited to: the system comprises a laser oscillator pumping trigger signal, an amplifier pumping trigger signal, an optical gate switch signal, other monitoring equipment trigger signals and a trigger signal of a post amplifier in a large laser system.

Further, the class a signal and the class B signal are each 1 or more signals.

Further, the trigger signal is a positive pulse signal or a negative pulse signal.

Further, the pulse shape of the trigger signal includes, but is not limited to: square, rectangular, saw-toothed. The signal strength and pulse shape of the class a and B signals may be of any type.

Further, in step (2), the class a signal is advanced or lagged with respect to the class B signal.

The invention has the beneficial effects that: the regulating method utilizes the time sequence control mode of the laser system to regulate the output frequency of the laser, the working frequency of the internal module of the laser is kept unchanged, the heat effect of the internal module of the laser is kept unchanged, and the stability of the laser output parameters is improved. Meanwhile, the method can control the time point of the laser output pulse and the number of the output pulses at will, and is simple and convenient to operate and easy to realize.

Drawings

FIG. 1 is a timing diagram of the class A signal and the class B signal in the method of the present invention;

FIG. 2 is a timing control block diagram of a Q-switched nanosecond medical cosmetic laser according to example 1;

fig. 3 is a timing control block diagram of the picosecond medical cosmetic laser in embodiment 2.

Detailed Description

The invention will be explained and explained in detail below with reference to the drawings.

The regulation and control method of the invention utilizes a time sequence control mode to regulate the output frequency of the laser. Specifically, the time sequence control signal is divided into two types, one is a signal for controlling laser generation, namely an A-type signal; the other is the other control signal, i.e. the class B signal. When the output frequency of the laser is adjusted, the A-type signal and the B-type signal keep fixed or approximately fixed repetition frequencies unchanged, and the output frequency of the laser is changed by changing the time delay relation between the A-type signal and the B-type signal.

As shown in fig. 1, there is laser output when the delay of the class a signal and the class B signal in the laser system is kept at T1; when the delay of the class a signal and the class B signal becomes T2, no laser light is output or nearly no laser light is output. The two states of the time delay T1 or T2 can be arbitrarily controlled by a laser control system, namely, the functions of adjusting the laser frequency and arbitrarily controlling the time point of the laser output pulse and the number of the output pulses can be realized.

Example 1

Fig. 2 is a timing control block diagram of the local oscillator level of a flash lamp pumped electro-optic Q-switched nanosecond medical cosmetic laser, which has different upper frequency limits of output laser according to different applications. We assume an upper trigger frequency of 10 Hz.

At the moment, the output frequency of the laser is set to be 10Hz, and when the laser starts to work, the time sequence control module provides two paths of trigger signals of 10Hz respectively for the Q-switching module and the pumping module. The Q-switched module receives the A-type signal, and the pumping module receives the B-type signal. According to the working principle of the laser, the trigger signal of the pumping module adjusts the trigger signal of the Q module in advance for 200-500 mus, and laser with the frequency of 10Hz is output at the moment.

If the output frequency of the laser is set to be 5Hz, when the laser starts to work, the time sequence control module provides two paths of trigger signals which are still 10Hz, and the trigger signals are respectively supplied to the Q-switching module and the pumping module. Different from the 10Hz working state, the time sequence relation between the Q-switched module trigger signal and the pumping module trigger signal is changed once every other trigger signal. Taking 10-time pulse as an example, the 1 st, 3 rd, 5 th, 7 th and 9 th trigger signals are the trigger signals of the pumping module, the Q-switching module trigger signals are adjusted in advance for 200-500 mus, and laser output exists at the moment; the 2 nd, 4 th, 6 th, 8 th and 10 th trigger signals are the trigger signals of the pump module and the delay Q-switched module, and no laser is output at the moment according to the laser principle.

According to the method, the output repetition frequency of the laser can be adjusted at will under the condition that the upper limit of 10Hz is not exceeded by changing the time sequence relation between the Q-switching module and the pumping module, and the functions of controlling the time point of the laser output pulse and the number of the output pulses can be realized.

Example 2

Fig. 3 is a timing control block diagram of a seed source + flash lamp pumped picosecond medical cosmetic laser with different upper frequency limits of the output laser for different applications. We assume an upper trigger frequency of 10 Hz.

If the laser repetition frequency is set to be 10Hz, when the laser starts to work, the time sequence control module provides two paths of trigger signals of 10Hz respectively for the seed source and the amplifier pumping module. The seed source module receives a class A signal, and the amplifier pumping module receives a class B signal. The seed source module trigger signal advances the amplifier pumping module trigger signal for 200-500 mus, and at the moment, the laser output with repetition frequency of 10Hz is provided.

If the repetition frequency of the laser is set to be 1Hz, when the laser starts to work, the time sequence control module provides two paths of trigger signals which are still 10Hz, and the trigger signals are respectively provided for the seed source and the amplifier pumping module. Different from the 10Hz working state, only the fixed 1-time trigger signal in each 10-time trigger signal is the seed source module trigger signal and advances the amplifier pumping module trigger signal for 200-500 mus, and laser output exists at the moment; the other 9 times of trigger signals are the trigger signals of the seed source module lagging behind the trigger signals of the pumping module of the amplifier, at this time, according to the laser principle, the amplifier module has no gain amplification effect on the laser output by the seed source module, the output laser is only very weak seed source pulses, and under the condition of not influencing practical application, the output laser can be approximately considered to be no laser output.

According to the method, the output repetition frequency of the laser can be adjusted at will under the condition that the upper limit of 10Hz is not exceeded by changing the time sequence relation between the seed source and the pumping module of the amplifier, and the functions of controlling the time point of the laser output pulse and the number of the output pulses can be realized.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and simplifications made in the spirit of the present invention are intended to be included in the scope of the present invention.

Claims

1. A method for regulating and controlling the output frequency of a laser is characterized by comprising the following steps:

(1) when the laser starts to work, the time sequence control module provides N paths of trigger signals, wherein N is more than or equal to 2, the trigger signals are divided into two types, one type is a signal generated by controlling the laser, namely an A-type signal; the other is other control signals, i.e. class B signals;

class B signals are 1 or more of the following: the method comprises the following steps that (1) a laser oscillation level pumping trigger signal, an amplifier pumping trigger signal, an optical gate switch signal, other monitoring equipment trigger signals and a trigger signal of a post-amplifier in a large laser system are obtained;

(2) the frequency of the laser internal module for receiving the A-type signal and the B-type signal is unchanged, and the delay time for receiving the A-type signal and the B-type signal is changed, so that the output frequency of the laser is changed; when the time delay of the A-type signal and the B-type signal in the laser system is kept at T1, laser output is available; when the delay of the class a signal and the class B signal becomes T2, no laser light is output or nearly no laser light is output.

2. The method of claim 1, wherein the class a signal is one or more of the following signals: the laser device comprises a laser device Q-switching signal, a seed source trigger signal, a clipping trigger signal and a trigger signal of a preceding laser device in a large laser system.

3. The method of claim 1, wherein the trigger signal is a positive pulse signal or a negative pulse signal.

4. A method of regulating and controlling the output frequency of a laser according to claim 1, wherein the pulse shape of the trigger signal is: square or saw-tooth.

5. The method of claim 1, wherein in step (2), the class A signal is advanced or delayed with respect to the class B signal.