Why Laser Beam Is Collimated?

Laser light from gas or crystal lasers is highly collimated because it is formed in an optical cavity between two parallel mirrors which constrain the light to a path perpendicular to the surfaces of the mirrors. In practice, gas lasers can use concave mirrors, flat mirrors, or a combination of both.

Are laser diodes collimated?

High-power laser diodes are often equipped with collimators only for the fast direction. Slow axis collimation can be done with an additional lens.

What is meant by a laser being monochromatic?

Monochromatic. The light emitted from a laser is monochromatic, that is, it is of one wavelength (color). In contrast, ordinary white light is a combination of many different wavelengths (colors).