Laser light has very specific properties, thanks to the way that electromagnetic radiation is generated, and these properties are especially useful in science and technology.
A special process produces laser light and this depends on some aspects of the interaction between the atoms that constitute matter and the electromagnetic radiation. To understand why laser light has unique properties, comprehension of the basic concepts of physics is required and these are explained in this chapter.
Key points to be understood include atomic structure, and how light originates and the path it takes through matter. The concept of the atom can be traced back to the ancient philosophers.
They defined the “atom,” from the Greek for “not divisible,” as the smallest possible portion of a rock that could be formed by repeatedly splitting a rock until it could not be split further and without changing the basic properties of the original rock. They believed the atom was indestructible, a belief that has
been disproved by scientific advances.
In 1808, the British scientist John Dalton scientifically defined the atom: “The atom is the smallest matter particle. It is indestructible.
Its mass and size cannot be changed. Atoms may combine with each other, creating other species of matter.” The current definition of the atom diverges from that of Dalton.
Unlike in current models, Dalton viewed the atom as a rigid sphere. Nevertheless, Dalton’s simplified model may still be used in describing situations such as chemical reactions and the law of definite proportions (Proust’s law), in which atoms maybe considered as rigid spheres.
