What is a laser ?

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Table of Contents

Definition

Definition

Before we begin, I should clarify what I mean by “LASER” in this article. Not all of their characteristics can be replicated in Blender, such as interference effects. Here, we will consider that a LASER is a monochromatic light beam with a small diameter (~1 mm) and a low divergence (< 1°).

The divergence of a laser can be calculated with the following formula : $$ \theta = \frac{\lambda}{\pi w_0} $$ With :

$\theta$ the beam divergence ;
$\lambda$ the laser wavelength (green is ~550 nm, red is ~650 nm) ;
$w_0$ the beam radius.

For example, a typical red laser pointer would be $\lambda = 650$ nm and $w_0 = 0.5$ mm, which would give $\theta = 0.02$°. In practice, the Blender spot light sources can only go down to $\theta = 1$°, and this is already hardly noticable in most common situations.