Polarization selective devices are commonly utilized as rear mirrors to generate high power cylindrical vector (CV) beams in the resonators. The modes of these polarization sensitive resonators are very significant for the generation and application of CV beams. Upon the scalar eigenvector method, a vectorial eigenvector method (VEM) was used to compute the CV modes of polarization-selective resonators. Then, different polarization dependent resonators were simulated with the VEM. We can find that both mode TE01* and mode TEM00 are the eigen modes of polarization sensitive symmetric confocal sphere resonator and when Rte=0.99 and Rtm=0.93, TE01* most possibly appears in the cavity with polarization sensitivity due to its lowest loss. In addition, the VEM was used to guide our design of a 45-degree three-fold cavity structure for high power radially polarized laser. The axicon mirrors with azimuthal polarization selection and four λ/4 phase shifters are used to obtain the output of radially polarized light.
Proc. SPIE. 7515, Photonics and Optoelectronics Meetings (POEM) 2009: Industry Lasers and Applications
KEYWORDS: Digital signal processing, Switching, Laser processing, Carbon dioxide lasers, Power supplies, Control systems, Laser cutting, Modes of laser operation, Signal detection, Pulsed laser operation
A switching power control system of fast axial flow CO2 lasers based on DSP is presented. The key techniques are
described in detail, include the control principle, realization method and program design. The experiment showed
that the system make the laser discharge stably and work in multi-mode. The discharge current can be adjusted from
3mA to 85mA continuously. 20-2000Hz frequency, 0-100% duty cycle laser pulse is achieved. The power supply
can improve the processing efficiency and quality.
A new kind of measure and control system for high power CO2 lasers in real-time is designed in order to improve
stabilization and accuracy of lasers power, and includes tow parts, one is the sample unit, made of a rear mirror, an
integrating sphere and an infrared detector, the other one is the and feedback control unit made of a PID controller. This
system adjusts output power of the lasers and makes the laser power stable in the required scope by the closed-loop
control system according to the feedback of laser power signal, which depends on the sampling of laser power
transmitted out of the rear mirror of the resonator. This system can detect and monitor the laser power on line and has no
influence on the output laser beam. It greatly enhances the stabilization (<±0.3%) and accuracy of the control.
Furthermore, it has such advantages as: compact construction, high stable performance and fast response and no need to
intercept the output laser beam just as the monitor with rotating pin sampling.
FAF(Fast Axial Flow) CO2 lasers are widely used in the areas of welding, cutting and texturing etc. These applications
require the laser power supply with higher performance. In the paper, a switch power supply for the FAF CO2 laser was
developed, which can provide continuous and pulsed discharge voltage. It makes a FAF CO2 laser to be competent for
complex machining. The switch power supply adopts the half-bridge resonant switching circuit. IGBT was adopted as
the switch device, which integrates the drive circuit and protection circuit. A microchip was used in the power as the
control core, which translates the control signal from users to corresponding driving signal for IGBT, gathers and deals
with the faults of the switch power supply. The experiment of the switch power supply was made on a fast axial flow
CO2 laser. The experiments show that the switch power supply can work on the FAF CO2 laser well. The discharge
current can be adjusted from 5mA to 120mA. It can switch the discharge freely between continuous mode and pulse
mode. The pulse frequency can be adjusted from 20 to 2000Hz. Utilizing the switching power supply, the efficiency of
the laser was improved. The dissipation power of the IGBT is very small, and the power supply brings fewer high
frequency harmonic, lower interference.
Characteristic modification of polymer surface using laser radiation is an attractive alternative to chemical processing. In recent years, many researches using laser to modify the surface of high polymer fibers or films have been done. In this article, several different methods are discussed. On hand of a series of experiments the properties and mechanisms of these technologies are compared. Effects of wavelength of lasers on poly (ethylene terephthalate) (PET) textiles are studied. Finally, the merits and drawbacks of laser processes in comparison with other competing techniques such as plasma processing are commented.
The new discharge system for RF-excited lasers is discussed in this paper, in which symmetric, homogeneous helical glow discharge by RF excitation can be got. The theoretical model based on the discharge system has been set up. The distributions of the electrical field and electron density inside the discharge tube are calculated. The advantages of the discharge system are consistent with the experimental results well.