Geometrical optics

The geometrical optics or ray optics uses the model rays of light and treated so simple, purely geometrical way, the path of light in lines.

A limited on a line beam of light comes to no physical reality, and one can consequently not realize it experimentally. Nevertheless, it is with the help of ray optics, the function of the optical image, which is the main task of technical optics, often describe with sufficient accuracy.

Confining the geometric optics on rays that intersect the optical axis is very flat, there is the so-called paraxial optics. For self-contained mathematical expressions for imaging equations can be found. It applies this method but mainly only appropriate when you want to get a quick basic overview before carrying out extensive investigations in more detail.

The geometrical optics can be mathematically interpreted as limiting case of wave optics for vanishingly small wavelength of light. However, they failed in this case, when the ratios for beams with high energy density or close to the border with the shadows (no light) to be examined.

Axioms of geometrical optics

As a common basis of ray optics can view the Fermat principle. It leads to the first two of the following axioms.

Applications

The main application of ray optics is the treatment of imaging through optical elements, devices and systems, such as lenses, spectacles, lenses, telescopes and microscopes.

Also, the ray-tracing method in the 3D computer graphics based on the laws of geometrical optics.

The mirages through a hot air layer over sunlit asphalt and other natural phenomena can be explained by application of this principle.

Confines

Effects which can not be described by the geometric optics include:

• The diffraction, which limits the resolving power of optical instruments. It can only be understood in the context of the wave theory or quantum mechanics.
• The interference can be detected also by the wave theory or quantum mechanics, and is, for example, for the operation of the compensation is essential.
• The polarization, which has to do with the quantum mechanical spin of the photons, but can also be explained by the wave theory. It is related to the birefringence of importance, and also the reflectance of thin layers, where it influences the quantity of the reflected light, see Fresnel formulas.
• The absorption and scattering of light.

Some methods of geometrical optics, in particular the Matrizenoptik, transferred, however, to the concept of Gaussian beams, which with partially takes into account the effects of wave optics.

Postgraduate

• Introduction to ray optics Detailed page about ray optics with many examples, pictures and experiments