When green laser pointer is used for the star gazing

 The laser module is used to assemble green laser pointer .The laser power density and beam pattern on the welding quality impact of the laser power density is a key parameter of the laser welding, for the same kind of metal, the laser power density of the material reaches the melting and boiling points of time. Reference to the welding Resources Network, the main factors affecting the quality of laser welding "reference white" potential for expansion millisecond pulse YAG laser welding applications. The same metal surface both power density and the underlying temperature and time relationship from Figure 2 - a visible laser power density the greater the time difference between the faster the time it reaches the melting and boiling points and surface underlying the less. Also, because of the different thermal conductivity and thermal diffusivity.  green laser pointer  is for many different purposes.
Figure 2 - 5 pulse period, the relative reflectivity of the material over time curve in this section refer to Cheng Long pairs, Feng Wei "laser welding processing parameters" Figure 2-5 for a laser pulse period , the relative reflectivity of the material versus time curve (curve 1 and 2, respectively, for changes in the reflectivity of the copper and steel). It can be seen that the laser pulse Start role of high reflectivity is quite high; when the surface temperature rose to the melting point, the reflectivity of the rapid decline; surface in a molten state, the reflection rate stable at a value; when the surface temperature continues to rise to the boiling point reflectance, and again declined.  green laser pointer can be used for the star gazing.
When negative defocus, the power density of material internal surface area is also high, easy to form a stronger melting, vaporization, so that the light pass deeper into the material. Therefore, in practical applications, when the requirements of the penetration depth larger negative defocus; welding thin material, it is appropriate defocus. From the focal volume changes are directly change the size of the spot diameter and the energy density increased 7, 11, defocus amount to the negative direction and the positive direction, mean spot diameter increases and the energy density decreases. Defocus amount to adjust the energy density. In the laser welding process, the spot diameter and the laser incident on the specimen formed by the initial size of the keyhole there is a certain correspondence between energy density determines the expansion speed of the molten pool. When green laser pointer is used for the star gazing.