Laser pointers

With a calibration laser, also called a collimation laser, the primary and secondary mirror of a Newtonian telescope can be correctly aligned. The use of such a laser is a simple and fast method, which also allows a high degree of accuracy.
The prerequisite is that both mirrors are adjustable. However, this is practically always the case with larger Newtonian telescopes with an aperture of 150 millimetres or more.