# Why do we see the beam of a laser?

### Why do we see the beam of a laser?

the laser beam propagates in a rectilinear and infinite way as long as it does not encounter any obstacle; thus the only thing visible from a laser is the spot that appears when the beam encounters an obstacle.

### What is a laser beam?

Device providing directional and almost monochromatic light radiation thanks to stimulated emission of radiation. Word ” laser » is the acronym for Light Amplification by Stimulated Emission of Radiation.

### What are the properties of a laser beam?

the laser is a light source with properties characteristics: It is a monochromatic light: it is made up of rays all having the same wavelength. The latter, therefore the color of the beam luminous depends on the medium laser used and the characteristics of the optical pumping.

### What are laser beams?

2measured at the collar. In practice, the laser beams are the result of the contribution of several transverse modes or are affected by diffraction by the intra-cavity components. The intensity and phase distribution can then be very inhomogeneous. This results in a real divergence θ and a neck diameter D

### What is the diameter of a laser beam?

. where D e-2 is the diameter at 1/e 2 measured at the neck. In practice, the laser beams are the result of the contribution of several transverse modes or are affected by diffraction by the intra-cavity components. The intensity and phase distribution can then be very inhomogeneous.

### How to calculate the width of a laser beam?

The width at half maximum is such that: (3.1-76)τ ≈ 1 Nδf = 1 Δf a) Intensity in a multimode laser beam when the modes oscillate randomly and independently

### How to stabilize the frequency of a laser?

The vibrations of the supports of the mirrors, the thermal drifts are as many causes of fluctuation of the frequency. It is possible to envisage stabilizing the frequency by forcing the laser to emit at maximum power.