Characteristics and Trend Analysis of CO2 Lasers
Carbon dioxide laser is a kind of laser with high continuous output power. It developed earlier and its commercial products are relatively mature. It is widely used in various fields such as material processing, medical use, military weapons, and environmental measurement. In the development and application of lasers, the production and application of CO2 lasers were earlier and more. As early as the late 1970s, CO2 lasers were directly imported from abroad for industrial processing and medical applications. Since the late 1980s, CO2 lasers have been widely introduced and used in the field of material processing.
In recent years, although CO2 laser processing equipment has become more and more popular, laser is a new tool after all, and laser processing technology is also different from traditional processing methods. Therefore, in the process of introducing and using CO2 lasers, the industry has encountered various This kind of problem has caused a lot of trouble to many manufacturers. This paper analyzes the application status and evolution of CO2 lasers in different fields, and proposes some problems that are often faced in the process of using CO2 lasers. According to the power of CO2 lasers, the application status and evolution of CO2 lasers in various industries are described. According to the situation, the main problems that CO2 laser users will face are listed and analyzed, and finally the prospect of CO2 laser application is put forward.
CO2 laser is a relatively important gas laser. This is because it has some prominent advantages:
First, it has relatively large power and relatively high energy conversion efficiency. General closed-tube CO2 lasers can have a continuous output power of tens of watts, which is far more than other gas lasers, and lateral-flow electro-excited CO2 lasers can have a continuous output of hundreds of thousands of watts. In addition, the transverse atmospheric pressure CO2 laser has also reached a high level in terms of energy and power output from the pulse, which is comparable to that of solid-state lasers. The energy conversion efficiency of CO2 lasers can reach 30-40%, which is also higher than that of ordinary gas lasers.
Second, it uses the transition between the vibrational and rotational energy levels of the CO2 molecule, and has relatively abundant spectral lines, with dozens of spectral lines in the laser output near 10 microns. The high-pressure CO2 laser discovered in recent years can even achieve continuously tunable output from 9 to 10 microns.
Third, its output band is exactly the atmospheric window (that is, the atmosphere is more transparent to this wavelength).
In addition, it also has the advantages of high optical quality of the output beam, good coherence, narrow line width, and stable operation. Therefore, it has many applications in the national economy and national defense, such as processing (welding, cutting, drilling, etc.), communications, radar, chemical analysis, laser-induced chemical reactions, surgery and so on.
Future CO2 lasers will develop in the following directions:
(1) High-power cross-flow CO2 laser.
High-power cross-flow CO2 laser is used for laser processing and heat treatment. The whole machine of the laser is an integrated box. The upper box of the box is equipped with an integrated discharge chamber, heat exchanger, fan system, inlet and outlet deflectors and optical resonant cavity, and the lower box of the box is equipped with a laser power supply, a charging and discharging system, and a vacuum pump. , ballast resistance box and control box. Compared with the prior art, the invention has the characteristics of compact structure, convenient installation, debugging and maintenance, high working efficiency of the laser, and miniaturization of the volume of the whole machine. It is mainly used in welding of diamond tools, automobile gears, automobile airbag gas generators, etc., laser surface quenching and cladding process and its special applications in steel roll surface fusion quenching, petrochemical parts surface repair, etc.
(2) Acousto-optically modulated QCO2 laser: In order to meet the application requirements in the fields of laser ranging, environmental detection, space communication and research on the interaction mechanism between laser and matter, the acousto-optically modulated QC02 laser was developed. According to various factors affecting the output of acousto-optical QCO2:laser, the main technical parameters of the laser output are theoretically analyzed and calculated by using the rate equation of Q-switched pulsed laser, and a method of optimal design of acousto-optical QCO2:laser is proposed. Validation experiments were carried out.
The pulse repetition frequency of the laser is 1Hz~50kHz, the output laser pulse width obtained when running at 1kHz is 180ns, and the peak power is 4062W, which is basically consistent with the theoretical calculation. The results show that: through the optimization of acousto-optic crystal (AO) and the rational design of the resonant cavity. High repetition frequency, narrow pulse width and high peak power output of small CO2 lasers can be achieved, and wavelength tuning and coding output of such lasers can be realized through grating line selection design and TTL signal control.
(3) Compact long-life RF-excited waveguide CO2 laser: In order to make CO2 lasers have wider applications in industrial processing and military, aluminum alloy drawn profiles are used as laser shells, and disk-mounted inductors are used instead of traditional wire-wound inductors. And all-metal sealing process, etc., developed a compact long-life RF excitation waveguide CO2 laser. It can output continuously or pulse output at a modulation frequency not higher than 20kHz, the maximum output power is 30W, the measured working life exceeds 1500h, and the storage life More than 1.5a. The results show that this laser has the characteristics of compact structure, stable output power, long working life, continuous and pulse modulation operation, etc., in addition to meeting the processing of various materials, it can also be used in military applications.
(4) New portable TEACO2 laser: It is a new portable laterally excited atmospheric pressure CO2 laser. The laser is powered by 4 No. 5 rechargeable batteries for DC power supply. Under the condition of 1Hz repetition frequency, it can work continuously for 1h. The size of the laser machine (including the power supply and control system) is 200nm×200mm×360mm, and the mass is less than 8kg. The laser uses ultraviolet electricity Corona pre-ionization method, the discharge is uniform and stable. In the case of free oscillation, the laser pulse output energy reaches 35mJ, and the output pulse width is 70ns.
(5) High-power continuous CO2 laser: Aiming at the problems of cracks and blade deformation caused by continuous laser cladding of helicopter engine turbine blades, a new power control scheme is adopted on the 5kW continuous cross-flow CO2 laser. The pulsed laser power output is realized. The cost and stability problems caused by the use of high-power switching power supply are overcome. The pulse modulation frequency can reach 5Hz, and the modulation duty cycle can reach 5% to 100%. When using 4kW peak power, 4Hz The cladding experiment of alloy powder StelliteX-40 was carried out on the surface of the K403 junction of the engine blade at the pulse repetition frequency and the duty ratio of 20%. The results show that the heat affected zone after cladding is reduced by 50% and the hardness is increased by 5% compared with the continuous laser. , The interface bonding performance is comparable to that of the base metal, and there is no cladding crack and blade deformation.
Over the years, my country's national science and technology plan has done a lot of digestion and absorption work on axial-flow CO2 lasers and cross-flow CO2 lasers. The cross-flow CO2 lasers developed by China, the United States, Japan and Russia have low cost and high power, but because the beam quality is not very good, they are mainly used for remanufacturing and heat treatment. The axial flow CO2 laser developed in Germany has been widely used in laser welding and cutting due to its good beam quality. However, due to the high cost, complex structure, high maintenance cost and high operating cost of axial-flow CO2 lasers, it is difficult for small and medium-sized enterprises to accept them, resulting in slow progress in their promotion and application. Therefore, axial-flow CO2 lasers are obviously not the development direction of CO2 lasers in my country.
