What is the divergence angle of a Gaussian beam?

What is the divergence angle of a Gaussian beam?

Divergence of Gaussian Beams and Beams with Poor Beam Quality. For a diffraction-limited Gaussian beam, the 1/e2 beam divergence half-angle is λ / (π w0), where λ is the wavelength (in the medium) and w0 the beam radius at the beam waist.

What is the divergence of a beam?

The beam divergence defines how much the beam spreads out over increasing distance from the optical aperture. Beam divergence is defined by the full angle. In laser diodes, beam divergence is specified with two values because of the presence of astigmatism (see Diodes vs. HeNe).

What are the properties of Gaussian beam?

The importance of Gaussian beams results from a number of special properties: Gaussian beams have a Gaussian intensity profile at any location along the beam axis; only the beam radius varies. A Gaussian beam remains Gaussian also after passing simple kinds of optical elements (e.g. lenses without optical aberrations).

What is divergence angle?

Angle of divergence means the angle between the straight lines connecting the centre of reference to the centre of the receiver and to the centre of the source of illumination.

How do you reduce divergence in a beam?

In regards to diffraction, the shorter the focal length, the smaller the spot size. More importantly, the larger the input beam diameter the smaller the spot size. By expanding the beam within the system, the input diameter is increased by a factor of MP, reducing the divergence by a factor of MP.

How is divergence measured?

For a circular beam, divergence is defined as the angular measure of how the beam diameter increases with the distance from the laser aperture. It is measured in milliradians (mrad) or degrees (°). Simply put, it tells you how the beam grows from the source to the target.

What is Gaussian intensity distribution?

Gaussian intensity distribution of a typical HeNe laser. The parameter ω0, usually called the Gaussian beam radius, is the radius at which the intensity has decreased to 1/e2 or 0.135 of its axial, or peak value. Another point to note is the radius of half maximum, or 50% intensity, which is 0.59ω0.

How do you calculate divergence angle?

Figure 1: the divergence half angle in x and y is defined as θ = Div/2.

How do you collimate a diverging beam?

To collimate a diverging light source with a lens, you can place the lens a distance away from the source, equal to the focal length of the lens. Here, we have a diverging beam of light and a positive lens at a distance equal to the focal length away.

How do you reduce the diameter of a beam?

The only way to make the spot size smaller is to use a lens of shorter focal length or expand the beam. If this is not possible because of a limitation in the geometry of the optical system, then this spot size is the smallest that could be achieved.