For outdoor signs and displays, acrylic, with its outstanding optical characteristics, weather resistance and formability, strongly dominates the picture.

For the further discussion, we shall thus assume an electron optical resolution of 80 Af and phosphor screen resolution of 60 Af.

For general computer use access technology such as screen readers, screen magnifiers and refreshable Braille displays has been widely taken up along with standalone reading aids that integrate a scanner, optical character recognition ( OCR ) software, and speech software in a single machine.

For example, the SEA-ME-WE 3 optical submarine telecommunications cable lands at both Medan and Jakarta connecting Europe with South eastern Asia ( several countries up to Japan ) and Australia ( Perth ).

For real, passive, optical systems, the output luminance is at most equal to the input.

For similar reasons, a bodyguard with a holster-carried, concealed weapon is typically not able to mount accessories onto the weapon, such as optical sights or forward handgrips.

For example, the Giant Magellan Telescope will have seven 8. 4 meter primary mirrors, with the resolving power equivalent to a optical aperture.

For example, the stability of bulk matter ( which consists of atoms and molecules which would quickly collapse under electric forces alone ), the rigidity of solids, and the mechanical, thermal, chemical, optical and magnetic properties of matter are all results of the interaction of electric charges under the rules of quantum mechanics.

For optical applications, this is characterized by the index of refraction.

For many materials ( for instance, semiconductors ), electrons move quickly from a high energy level to a meta-stable level via small nonradiative transitions and then make the final move down to the bottom level via an optical or radiative transition.

For example, the term subwavelength-diameter optical fibre means an optical fibre whose diameter is less than the wavelength of light propagating through it.

For planetary rings, the optical depth is the proportion of light blocked by the ring when it lies between the source and the observer.

* For an optical cavity consisting of two mirrors, confocal means that they share their foci.

For the optical regime, see beam divergence.

For a single-mode optical fiber, the cutoff wavelength is the wavelength at which the normalized frequency is approximately equal to 2. 405.

For an optical fiber, the effective mode volume is the square of the product of the diameter of the near-field pattern and the sine of the radiation angle of the far-field pattern.

For both families, the lowest-order solution describes a Gaussian beam, while higher-order solutions describe higher-order transverse modes in an optical resonator.

: Note: For optical fiber dispersion measurement purposes, the quantity of interest is group delay per unit length, which is the reciprocal of the group velocity of a particular mode.

For a Gaussian intensity ( i. e. power density, W / m < sup > 2 </ sup >) distribution in a single-mode optical fiber, the mode field diameter is that at which the electric and magnetic field strengths are reduced to 1 / e of their maximum values, i. e., the diameter at which power density is reduced to 1 / e < sup > 2 </ sup > of the maximum power density, because the power density is proportional to the square of the field strength.

For example, using a long pulse length, it may possible to measure attenuation over a distance of more than 100 km, however in this case an optical event may appear to be over 1 km long.

For optical fibers, a power-law index profile is an index of refraction profile characterized by

For an optical fiber or waveguide, a radiation mode or unbound mode is a mode which is not confined by the fiber core.

For the same reason, the output fiber plate is planoconcave, its exposed flat side permitting contact photography if a permanent record is desired.

For phosphor to fiber and fiber to air surfaces, and assuming Af, we obtain Af percent.

For instance, nanotubes form only a tiny portion of the material ( s ) in ( primarily carbon fiber ) baseball bats, golf clubs, or car parts.

For example, the fibers in carbon fiber materials and rebars in reinforced concrete are oriented to withstand tension.

For this migration, ISDN services will be retired, and fiber optic services are recommended as an alternative.

For example, both PNGinc and International Turbine And Power, LLC use carbon fiber discs in their Tesla turbine designs.

For these purposes, manufactured rubber fiber is made as either an extruded round fiber or rectangular fibers that are cut into strips from extruded film.

For step index fiber, light entering the fiber will be guided if it falls within the acceptance cone of the fiber, that is if it makes an angle with the fiber axis that is less than the acceptance angle,

For step-index multimode fiber, the acceptance angle is determined only by the indices of refraction of the core and the cladding:

For example, sending ones and zeros across a wire, fiber, etc.

For plastic-clad silica ( PCS ) fibers, which have a strippable polymer cladding ( not to be confused with the polymer overcoat of an all-silica fiber ), the reference surface may be the core.

For the case of a purely inertial autonavigator consisting of three restrained gyros, a coordinate system is used where the sensitive axis of the X accelerometer is parallel to the east-west direction at the base point, and the Y accelerometer sensitive axis is parallel to the north-south direction at the base point.

For an ellipse, the aspect ratio denotes the ratio of the major axis to the minor axis.

For a rigid body rotating around an axis of symmetry ( e. g. the blades of a ceiling fan ), the angular momentum can be expressed as the product of the body's moment of inertia, I, ( i. e. a measure of an object's resistance to changes in its rotation rate ) and its angular velocity ω:

For the case of an object that is small compared with the radial distance to its axis of rotation, such as a tin can swinging from a long string or a planet orbiting in a circle around the Sun, the angular momentum can be expressed as its linear momentum,, crossed by its position from the origin, r. Thus, the angular momentum L of a particle with respect to some point of origin is

For an object with a fixed mass that is rotating about a fixed symmetry axis, the angular momentum is expressed as the product of the moment of inertia of the object and its angular velocity vector:

For many applications where one is only concerned about rotation around one axis, it is sufficient to discard the pseudovector nature of angular momentum, and treat it like a scalar where it is positive when it corresponds to a counter-clockwise rotation, and negative clockwise.

For an object with a fixed mass that is rotating about a fixed symmetry axis,

For twisting rotation to exist, it is necessary to tilt the body sideways after takeoff, so that there is now a small component of this horizontal angular momentum vector along the body's long axis.

For a flow, it will occur when there are eigenvalues on the imaginary axis.

For the special case where the minor axis is half the major axis, these become:

For an ellipse in canonical position ( center at origin, major axis along the X-axis ), the equation simplifies to

For Earth, on average L is equal to 1. 384 km, which is much larger than the Moon's semimajor axis of 3. 844 km.

For all pictures the magnetic quantum number m has been set to 0, and the cross-sectional plane is the xz-plane ( z is the vertical axis ).

For example, the centrifugal force that appears to emanate from the axis of rotation in a rotating frame increases with distance from the axis.

For the case of Bragg reflection only the lowest-order reflection is allowed if the light is incident along the helical axis, whereas for oblique incidence higher-order reflections become permitted.

For instance, electrons and positive ions trapped in the dipole-like field near the Earth tend to circulate around the magnetic axis of the dipole ( the line connecting the magnetic poles ) in a ring around the Earth, without gaining or losing energy ( this is known as Guiding center motion ).

# For a given orbit, the ratio of the cube of its semi-major axis to the square of its period is constant.

For example, when a plate is thrown, the plate may have some rotation around an axis that is not its axis of symmetry.

For a generic solid object without any axis of symmetry, the evolution of the object's orientation, represented ( for example ) by a rotation matrix that transforms internal to external coordinates, may be numerically simulated.

For example, the earth is subject to local torque induced precession due to the gravity of the sun and moon acting upon the earth ’ s axis, but at the same time the solar system is moving around the galactic center.