The manufacturer wants to get more market share of laser pointer

The manufacturer wants to get more market share of  laser pointer .
So when the light waves along the angular direction of the optical axis into θm transmission can achieve phase matching, rather than with the normal of the plane of incidence angle. In order to reduce reflection losses and easy to adjust, so that the fundamental frequency of normal incidence to the crystal surface. The processing of frequency-doubling crystal in accordance with a certain direction of cut crystal, so that the crystal normal direction and the optical axis direction at θm, as shown in Figure 2-5. θm baseband optical ω crystal Figure 2-5 of the nonlinear crystal cut Z crystal surface normal above described incident light incident at an angle crystals, birefringent crystal, the refractive index change to compensate for the normal dispersion to achieve phase matching, called the angle of phase matching. Angle phase matching can be divided into two categories. The supplier wants to sell more laser pointer .laser pointer  can be especially used in the dark night to indicate the directionAlso need some of the practical application of optical frequency conversion technology coherent radiation sources of different wavelengths. Laser technology awareness and the use of human light reached a new level. The history of the birth of the laser can be divided into several stages, in 1916 Einstein proposed the concept of stimulated emission is an important theoretical basis. The theory is that the material particles in the high-energy state of the energy is equal to 2 level of the energy difference between the photon will be converted to a low state, and generating a two-photon-photon emission, which is stimulated radiation. Such radiation output light amplification and a coherent light source, such as multiple photon emission directions, frequency, phase, polarization, identical. Special phenomenon of laser pointers that can help manufacturers to attract more customers.
Since then, the establishment and the development of quantum mechanics in the microstructure of the material and the law of motion have a better understanding of the microscopic particles of energy distribution, transition and photon radiation is more eloquent proof of this objectively more comprehensive love Einstein's theory of stimulated emission, further laid the theoretical basis for the generation of lasers. The late 1940s, after the birth of quantum electronics, will soon be used to study the interaction of electromagnetic radiation with a variety of micro-particle system, and the development of a number of devices. The rapid development of scientific theories and technology to create the conditions for the invention of the laser. 1951, American physicist, Purcell, successful experiments led to the inversion, and 50 kHz per second by stimulated emission of radiation. The different special appearance laser pointer to attract different types of customers.The laser range of this kind of laser pointer can reach up to 2 miles