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The principal ray or chief ray (sometimes known as the b ray) in an optical system is the meridional ray that starts at an edge of an object and passes through the center of the aperture stop. [5] [8] [7] The distance between the chief ray (or an extension of it for a virtual image) and the optical axis at an image location defines the size of ...
An optical instrument is a device that processes light waves (or photons), either to enhance an image for viewing or to analyze and determine their characteristic properties. Common examples include periscopes , microscopes , telescopes , and cameras .
Geometrical optics, or ray optics, is a model of optics that describes light propagation in terms of rays. The ray in geometrical optics is an abstraction useful for approximating the paths along which light propagates under certain circumstances. The simplifying assumptions of geometrical optics include that light rays:
In physics, physical optics, or wave optics, is the branch of optics that studies interference, diffraction, polarization, and other phenomena for which the ray approximation of geometric optics is not valid. This usage tends not to include effects such as quantum noise in optical communication, which is studied in the sub-branch of coherence ...
A system is focal if an object ray parallel to the axis is conjugate to an image ray that intersects the optical axis. The intersection of the image ray with the optical axis is the focal point F ′ in image space. Focal systems also have an axial object point F such that any ray through F is conjugate to an image ray parallel to the optical axis.
Subscripts 1 and 2 refer to initial and final optical media respectively. These ratios are sometimes also used, following simply from other definitions of refractive index, wave phase velocity, and the luminal speed equation:
This is the basic principle behind fiber optics in which light is guided along a high index glass core in a lower index glass cladding. The basic principles behind optical waveguides can be described using the concepts of geometrical or ray optics, as illustrated in the diagram.
The most famous compound optical instruments in science are the microscope and the telescope which were both invented by the Dutch in the late 16th century. [110] Microscopes were first developed with just two lenses: an objective lens and an eyepiece. The objective lens is essentially a magnifying glass and was designed with a very small focal ...