Glossary

ACCEPTANCE ANGLE: The maximum cone angle, which successfully pass through an optic while meeting the desired performance conditions. The f-number is another way to express the same concepts.

ALPHA PARTICLES: A highly ionizing form of particle radiation that has a low penetration. They consist of two protons and two neutrons bound together into a particle identical to a helium nucleus (He2+). Alpha radiation consists of helium nuclei and is stopped by a sheet of paper.

ANGLE OF INCIDENCE: The angle of the incoming light with respect to the polarizer. The standard convention of normal incidence being zero degrees is used.

ANGSTROM: 1 Ångström (Å) = 1.0 x 10-10 meters = 0.1 nm = 100 picometers

ANGULAR APERATURE: A measure of the size of the cone of light which can pass through an optical component.

ANODE: An electrode through which electric current flows into a polarized electrical device.

BEAM –SPLITTING POLARIZERS: Beam-splitting polarizers split the beam into two beams of differing polarization. Unlike absorptive polarizers, beam splitting polarizers do not need to absorb and dissipate the energy of the rejected polarization state, and so they are more suitable for use with high intensity beams such as laser light.

BETA PARTICLES: (ß) High-energy, high-speed electrons, a form of ionizing radiation. The production of beta particles is termed beta decay. Beta radiation, consisting of electrons, is stopped by an aluminum plate.

BIREFRINGENCE: A property of light that is created by an anisotropic structure in which the optical properties are different for each polarization. A wire-grid polarizer is a good example of a birefringent structure in which the optical properties in the two polarizations are very different, one direction being metallic and the other direction dielectric in nature. Birefringence is typically used to create waveplates or similar devices.

BREWSTER’S ANGLE: (also known as the polarization angle) is an optical phenomenon named after the Scottish physicist, Sir David Brewster. When light moves between two media of differing refractive index, generally some of it is reflected at the boundary. At one particular angle of incidence, however, light with one particular polarization cannot be reflected. This angle of incidence is Brewster's angle, θB. The polarization that cannot be reflected at this angle is the one for which the electric field of the light waves lies in the same plane as the incident ray and the surface normal. Light with this polarization is said to be p-polarized, because it is parallel to the plane. Light with the perpendicular polarization is said to be s-polarized, from the German senkrecht-perpendicular. When unpolarized light strikes a surface at Brewster's angle, the reflected light is always s-polarized.

CATHODE: An electrode through which electric current flows out of a polarized electrical device.

CONTRAST RATIO: A display system defined as the ratio of the luminosity of the brightest and the darkest color a system is capable of producing.

DEIONIZED WATER: Water that lacks ions; such as cations from sodium, calcium, iron, copper, and anions such as chloride and bromide. This means it has been purified from all other ions except H3O+ and OH-, but it may still contain other non-ionic types of impurities such as organic compounds. The lack of ions causes the water's resistivity to increase.

DIODE: A component that restricts the direction of movement of charge carriers. It allows an electric current to flow in one direction, but blocks it in the opposite direction.

ELECTROMAGNETIC RADIATION: A self-propagating wave in space with electric and magnetic components. These components are in phase with each other, oscillate at right angles to each other and oscillate to the direction of propagation. Electromagnetic radiation is classified into types according to the frequency of the wave: these types include, in order of increasing frequency, radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays and gamma rays. EM radiation carries energy and momentum, which may be imparted when it interacts with matter. Interference is the superposition of two or more waves resulting in a new wave pattern. If the fields have components in the same direction, they constructively interfere, while opposite directions cause destructive interference.

ELECTRONS: Subatomic particles which have a negative charge, and a size which is so small as to be almost immeasurable, and which are the least heavy of the three principal components of an atom.

EXTINCTION: The ratio between Ts and Tp in the transmitted beam or between Rp and Rs in the reflected beam. It is also referred to as the contrast ratio in the transmitted or reflected beam.

ION: An atom or group of atoms that normally are electrically neutral and achieve their status as an ion by loss or addition of one or more electrons. The simplest ions are the proton (a hydrogen ion, H+, positive charge), and alpha particle (helium ion, He2+, consisting of two protons and two neutrons). A negatively charged ion, which has more electrons in its electron shells than it has protons in its nuclei, is known as an anion due to its attraction to anodes. A positively-charged ion, which has fewer electrons than protons, is known as a cation due to its attraction to cathodes. Ions are denoted in the same way as electrically neutral atoms and molecules except for the presence of a superscript indicating the sign of the net electric charge and the number of electrons lost or gained, if more than one. For example: H+, SO42-.

JFET: Junction Field Effect Transistor. The common transistor is called a junction transistor, and it was the key device which led to the solid state electronics revolution. In application, the junction transistor has the disadvantage of low input impedance because the base of the transistor is the signal input and the base-emitter diode is forward biased. Another device achieved transistor action with the input diode junction reversed biased is called a "field effect transistor" or a "junction field effect transistor", JFET. With the reverse biased input junction, it has very high input impedance. Having high input impedance minimizes the interference with or "loading" of the signal source when a measurement is made.

JOULE: One joule is the amount of energy required to lift a one kilogram object up by a height of about 100 centimeters on the surface of the Earth, by the most efficient method.

LASER: (acronym for Light Amplification by Stimulated Emission of Radiation) is an optical source that emits photons in a coherent beam.

LINE WIDTH: The width of the aluminum lines that are on the surface of the glass. Typically the ProFlux™ line width is approximately 65 nm, although this may vary based upon the desired performance of the polarizer.

THE PELTIER EFFECT: A creation of a heat difference from an electric voltage. It occurs when a current is passed through two dissimilar metals or semiconductors that are connected to each other at two junctions (Peltier junctions). The current drives a transfer of heat from one junction to the other: one junction cools off while the other heats up; as a result, the effect is often used for thermoelectric cooling. An interesting consequence of this effect is that the direction of heat transfer is controlled by the polarity of the current; reversing the polarity will change the direction of transfer and thus the sign of the heat absorbed.

PHASE VELOCITY: The rate at which the phase of the waveform is moving.

PHOTON: The elementary particle responsible for electromagnetic phenomena. It mediates electromagnetic interactions and makes up all forms of light. The photon has zero invariant mass and travels at the constant speed c, the speed of light in empty space. However, in the presence of matter, a photon can be slowed or even absorbed, transferring energy and momentum proportional to its frequency.

PIN DIODE: PIN diode (p-type, intrinsic, n-type diode) is a diode with a wide, undoped intrinsic semiconductor region between p-type semiconductor and n-type semiconductor regions.

PINHOLE: A bare spot on the surface of the polarizer such that light can pass through without being polarized. This type of artifact impacts contrast but is not visible in transmission.

PITCH: The distance between the leading edge of two consecutive lines. This is also called the period. The standard ProFlux™ polarizer has a pitch of 144nm.

PLASMA: A collection of gas-like ions, or even a gas containing a proportion of charged particles, is called plasma. The free electric charges make the plasma electrically conductive so that it responds strongly to electromagnetic fields.

POLARIZER: A device that converts unpolarized or a mixed beam of electromagnetic waves (such as laser light) into a beam with a single polarization state. Polarizers can be divided into two general categories: absorptive polarizers, where the unwanted polarization states are absorbed by the device, and beam-splitting polarizers, where the unpolarized beam is split into two beams with opposite polarization states.

RAD: A unit of radiation dose. RAD stands for "radiation absorbed dose". The rad is a unit of radiation absorption defined in terms of the energy actually deposited in the tissue. One rad is an absorbed dose of 0.01 joules of energy per kilogram of tissue.

RADIATION: The process of emitting energy in the form of waves or particles. Various types of radiation can be distinguished depending on; the properties of the emitted energy/matter, the type of the emission source, properties and purposes of the emission, etc.

REFRACTION INDEX: The refractive index of a material is the factor by which the phase velocity of electromagnetic radiation is slowed in that material, relative to its velocity in a vacuum.

REFRACTIVE INDEX: The refractive index of a material is the factor by which the phase velocity of electromagnetic radiation is slowed in that material, relative to its velocity in a vacuum.

REM: The röntgen (roentgen) equivalent in man or rem is a unit of radiation dose. It is the product of the absorbed dose in röntgens (R) and the biological efficiency of the radiation. A rem is a large amount of radiation, so the millirem (mrem), which is one thousandth of a rem, is often used for the dosages commonly encountered, such as the amount of radiation received from medical x-rays and background sources.

Rp: The symbol that represents the reflected "p" polarization.

Rs: The symbol that represents the reflected "s" polarization.

SIEVERT: The sievert (symbol: Sv) is a unit of dose equivalent. It attempts to reflect the biological effects of radiation as opposed to the physical aspects.

SKEW-RAY: A one geometric ray in a cone of light rays passing through the polarizer in which this geometric ray is not close to the plane of incidence defined by the optical axis nor to the orthogonal plane. When passing through a McNeille polarizer or cube beamsplitter, the skew-ray transmitted polarization vector will be significantly rotated in comparison to the polarization vector transmitted along the optical axis. When passing through a ProFlux™ polarizer, the skew-ray transmitted polarization vector is not rotated in comparison to the polarization vector transmitted along the optical axis.

SPOT: An opaque area on the surface of the polarizer that does not allow any light through. This type of artifact impacts transmission and may not be visible in crossed polarizer conditions.

SPUTTERING: A physical process where atoms in a solid target material are ejected into the gas phase due to bombardment of energetic ion. It is commonly used for thin-film deposition. Sputtering is largely driven by a momentum exchange between the ions and atoms in the material, due to collisions. The process can be thought of as atomic billiards, with the ion (cue ball) striking a large cluster of close-packed atoms (billiard balls). Although the first collision pushes atoms deeper into the cluster, subsequent collisions between the atoms can result in some of the atoms near the surface being ejected away from the cluster. The number of atoms ejected from the surface per incident ion is called the sputter yield and is an important measure of the efficiency of the sputtering process. Other things the sputter yield depends on are the energy of the incident ions, the masses of the ions and target atoms, and the binding energy of atoms in the solid.

TEC (PELTIER COOLER): A Peltier cooler heater or thermoelectric heat pump is a solid-state active heat pump which transfers heat from one side of the device to the other. Peltier coolers are also called thermo-electric coolers (TEC).

THERMOELECTRIC EFFECT: The Peltier-Seebeck effect, or thermoelectric effect, is the direct conversion of thermal differentials to electric voltage and vice versa.

TORR: (Millimeter of mercury (mmHg)) A unit of pressure. It is the atmospheric pressure that supports a column of mercury 1 millimeter high. Normal atmospheric pressures can support 760mm of mercury, so 1/760 of an atmosphere is a convenient measurement point expressed as torr.

Tp: The symbol that represents the transmitted or "p" polarization

Ts: The symbol that represents the transmitted "s" polarization

VC: PFU series VC0 VC2

WAVELENGTH: The distance between repeating units of a wave pattern. It is commonly designated by the Greek letter lambda (λ).

WIRE-GRID POLARIZER: A regular array of fine metallic wires, in a plane perpendicular to the beam. Electromagnetic waves have part of their electric fields aligned parallel to the wires. As those electric fields contact the wires it generates movement of electrons along the wires: the wave is reflected back across the beam. For waves perpendicular to the wires, electrons cannot move far across the width of each wire, so very little energy if reflected, and the wave travels through.

WIRE HEIGHT: The thickness of the aluminum wires as determined by the desire to satisfy the following conditions: First, the aluminum thickness should be enough to be optically opaque and second, the aluminum thickness should be enough to achieve the desired transmission and extinction. The wire height of the ProFlux™ polarizer is typically between 100nm and 200nm. X-RAYS: (or Röntgen rays) are a form of electromagnetic radiation with a wavelength in the range of 10 to 0.01 nanometers. X-rays are a form of ionizing radiation and as such can be dangerous. X-rays are low a spectrum, low intensity form of gamma-rays (γ). Gamma (and x-ray) radiation is eventually absorbed as they penetrate a dense material, such as lead.