The ability of the eye to adjust its focusing power (the crystalline lens) to objects that are closer or farther away.
Additive methods of color production
Mixing of the additive primary colors to produce other colors of the spectrum.
Additive primary colors
Red, blue, and green, which mixed in certain combinations produces the other colors of the spectrum and when all mixed together shows white light.
Angle of Refraction
The angle of change in direction that the light wave makes when it undergoes refraction.
The magnifying power of a magnifying glass, expressed as the ratios of the angular sizes of an object, normally and through the instrument.
Materials such as quartz and ice where the characteristics of it are different depending on which way the light rays travel.
A telescope where the final image is inverted, which is usually used by astronomers.
Describes the relationship between the wavelength traveling through a grating and the spacing within the crystal that serves for diffraction.
Center of curvature (C)
The point on the optics axis that corresponds to the center of the sphere at which the mirror forms a section.
Chief (radial) ray
A ray that travels through the center of curvature along the mirror?s surface and is reflected back along its original.
White light is dispersed because of different indexes of refraction within a lens.
An instrument composed of two convex lenses that combine to increase magnification.
Part of the composition of the retina; it is cone-shaped. It is more used for intense light that the brain will translate into colors.
The angle of incidence which produces a 90 degree angle of refraction; the light ray does not enter the second medium but travels along the surface between the two mediums.
A converging or convex lens inside the eye, located behind the iris and composed of microscopic glassy fibers.
A property that some birefrigent materials exhibit, where one polarized beam of light is absorbed more than the other, and the light that leaves the crystal is plane polarized, or polarized in one direction.
A series of parallel, very fine, closely placed slits on a panal that often gives rise to an iridescent effect (i.e. CDs).
When light enters a material that has different indexes of refraction and is separated (e.g. prism).
When a material exhibits birefringence, there are two beams of light polarized. The extraordinary ray is the beam that is refracted when passing through the crystal.
The greatest distance at which the normal eye can see objects clearly, and is taken to be infinity.
A disease/condition of the eye where it is unable to see things that are close to it. The physics behind it is that the image is being focused not exactly on the retina, but behind it.
A new field of optics where transparent fibers are used to transmit light across distances.
A ray that appears to travel through the focal point and reflects back in a path parallel to the optic axis.
Every point on a light wave can be considered as a source of secondary waves and the line or surface tangent to all these secondary waves defines a new position of the wave front.
When two waves interact and effect each other depending on their wavelengths, places of interaction, and other factors.
Irregular (diffuse) reflection
Reflection that occurs when the reflecting surface is rough; reflected light rays are not parallel even if the rays are at the same angle of incidence.
Materials such as glass where the characteristics are the same no matter which way the light rays travel.
The ratio of an object?s image?s height compared to the object?s actual height.
LCD (Liquid Crystal Display)
Crystals that are melted and flow like liquid but still have the orderly composition that light needs in polarization; often used in calculators and digital watches.
A single convex lens that inflates the size of an object to allow it to be seen more clearly.
Dust, water droplets, and particles of the lower region of the atmosphere cause this kind of scattering, which takes place when the particles that spread the emitted substance emission are bigger than the emitted wavelengths themselves. It is not as wavelength dependent as Rayleigh's scattering. Mie scattering makes clouds look white.
The position closest to the eye at which objects can be seen clearly and depends on the extent the lens can be deformed by accommodation.
A disease/condition of the eye where it is unable to see things that are at a distance. The physics behind it is that the image is being focused not exactly on the retina, but in front of it.
A technique that is used to check the smoothness and equilibrium of lenses through an interference where irregularities in the lens cause distortions.
This kind of scattering occurs in the lower regions of the atmosphere, but unlike Mie scattering, its intensity is not dependant on wavelength. Nonselective scattering is a major cause of haze.
The ability of a material to polarize light and then change its direction (i.e. the transparent material used to make 3-D glasses).
When a material exhibits birefringence, there are two beams of light polarized. The ordinary ray is the beam that passes through the crystal without being deflected.
A ray that travels parallel to the optic axis and is reflected through the focal point.
Partially polarized light
The light rays are going in a general direction but not altogether oriented.
Polarization by refraction
When light is refracted continuously off a stack of glass plates, instead of only one, and thus polarization increases so that the intensity of the light goes up as well.
Polarizing angle (Brewster angle)
When light hits a surface such as glass, it is usually partially reflected and partially refracted depending on the angle of incidence. This causes the light ray to become either polorized, partially polarized, or unpolarized. If the angle of incidence is exactly 90 degrees, this results in complete polarization of the beam and is known as the Brewster angle.
A ray that travels through the center of the sphere and is reflected back along the path it came.
A ray that travels through the center of the sphere and is reflected back along the path it came.
A line drawn perpendicular to a series of wave fronts and pointing in the direction that the wave is going.
An accepted condition of resolution that states that if two images have coinciding diffraction maximum and minimum patterns, they are said to be resolved.
The equation that shows the relationship between scattering and the wavelengths of the light rays; the bigger the wavelength, the less the scattering.
An image that is formed when light rays are reflected by a spherical mirror from the object to the eye; light actually radiates from such images (e.g. movie screen).
A telescope that uses a single large, concave, parabolic mirror. Because of its parabolic nature, the mirror does not have spherical or chromatic aberration and only one surface needs to be prepared and polished.
When light is transmitted through an extraordinarily fine diffraction grating that is also photosensitive and causes a colorful iridescent effect.
A refracting telescope works similarly to a compound microscope and also magnifies objects. It uses convex lenses and the phenomenon of refraction. It too has an objective and an eyepiece. To attain the greatest magnification, the focal length of the objective should be maximized and that of the eyepiece should be minimized. Two types of refracting telescopes are astronomical and terrestrial telescopes.
Regular (specular) reflection
Reflection that occurs when the reflecting surface is smooth; reflected light is parallel if the rays are at the same angle of incidence.
1) Separating something into its basic components (white light into colors). 2) The specific detail that an image can be tuned to; the clearness of an image.
The minimum distance that a lens needs between two points so that the images can be resolved.
An area that is photo-sensitive within the eye, whose surface is in contact with light rays. In back of this surface runs many optic nerves that send signals to the brain.
Part of the composition of the retina; it is rod-shaped, hence the name. It is more sensitive to light and can help one to see when the surrounding is dim (twilight vision).
Light may be absorbed and re-radiated from the particles of the medium that it travels through (i.e. air), which is the reason why the sky is blue.
A law that shows the relationship between angles of incidence and angles of refraction for a light wave.
The effect that the greater distance between the incident and the axis results in a greater distance between the mirrored ray and focal point.
Spherical mirror equation
An equation that relates the distances that a ray travels and the focal point.
Subtractive method of color production
Color is perceived by a method known as subtraction, where the color seen is the color not reflected by the pigment.
Subtractive primary pigments
Cyan, magenta, and yellow, which are the complementary colors of the additive primary colors and combine together to form black.
A telescope where the final image is right-side up, which is more useful for those viewing objects on Earth.
Total internal reflection
The condition in refraction where light does not pass through the surface but is internally reflected; the angle that the light is refracted is greater than the critical angle.
Transmission axis (polarization direction)
When certain birefrigent materials are used, such as polymers, the molecules can orient themselves into chains. The transmission axis is perpendicular to this chain.
When light is transmitted through a diffraction grating, often caused by an extremely fine wire grating.
An image that is formed when the light rays are reflected by a planar mirror from the object to the eye, so that the object actually appears to be behind the mirror; light does not actual radiate from such images.