More functions can be added to Laser Pointer

More functions can be added to Laser Pointer .
Liquid dye substances with very wide, which makes it required by the mode-locked laser active medium. The 1970s, people use the synchronously pumped mode-locked dye laser to obtain the order of ps light pulses, and later the collision mode-locked dye laser and cavity pulse compression technology, the optical pulse width compression to 6fs. The semiconductor laser is a semiconductor material of the laser as a laser material. It has ultra-compact, high efficiency, simple structure, inexpensive and high-speed work a number of advantages. Come out since 1962, especially since the 1980s, the extremely rapid development. It is the most important light source in the field of optical communications, and important in many aspects of the CD, VCD, DVD player, computer CD-ROM drive, laser printer, holography, laser alignment, ranging and medical applications. It is the short and small type  Laser Pointer .
The semiconductor laser is injected by the laser amplifier. Although it is a necessary condition for the laser and other lasers, must also meet the conditions of population inversion, resonant, but it very different from several laser excitation mechanism discussed earlier. Between the electronic transition in the conduction band of the semiconductor material of the electronic states and the hole in the valence band state, rather than atomic, molecular, ion lasers as between the two to determine the level. Semiconductor materials have stimulated absorption, stimulated emission and spontaneous emission process. Current or optical excitation, the semiconductor valence band electrons can gain energy, the transition to the conduction band, forming a hole in the valence band, which is equivalent to stimulated absorption process. 
Beryllium oxide ceramic with excellent performance compared to an ideal material, but it is highly toxic, affecting the application. The widely used high-purity dense graphite. Since graphite is a good conductor, so in order to maintain the discharge, the graphite discharge tube segment structure, shown in Figure (5-14) as shown in. The entire structure is placed in a water-cooled units within the quartz tube, the ends were to provide the cathode of the electron emission and collection of electronic graphite anode. In order to provide a large emission current, usually between heated barium tungsten cathode. In order to make the Ar + laser stability, Ar + laser should be set back to the trachea. This is because in the high current density, low-pressure discharge, there is a serious gas pump effect.