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Optics Glossary



OPTICS TERMS AND CONCEPTS

 

ACCEPTANCE ANGLE
The Acceptance Angle is 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.
ANGLE OF INCIDENCE
This term is defined as the angle of the incoming light with respect to the polarizer. The standard convention of normal incidence being zero degrees is used.
ANGULAR APERTURE
Angular aperture is a measure of the size of the cone of light which can pass through an optical component.
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.
A stack of plates at Brewster's angle to a beam reflects off a fraction of the s-polarized light at each surface, leaving a p-polarized beam. Full polarization at Brewster's angle requires many more plates than shown.
A stack of plates at Brewster's angle to a beam reflects off a fraction of the s-polarized light at each surface, leaving a p-polarized beam. When light reflects at an angle from an interface between two transparent materials, the reflectivity is different for light polarized in the plane of incidence and light polarized perpendicular to it. Light polarized in the plane is said to be p-polarized, while that polarized perpendicular to it is s-polarized. At a special angle known as Brewster's angle, no p-polarized light is reflected from the surface, thus all reflected light must be s-polarized, with an electric field perpendicular to the plane of incidence.
BIREFRINGENCE
Birefringence is 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.
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.
Extinction
Extinction is 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.
Line Width
Line Width: This term is defined as 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.
Pinhole
Pinhole: This artifact is defined as 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 (Period)
Pitch (Period): This term is defined as 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.
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.
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.
Rp
Rp is the symbol that represents the reflected "p" polarization.
Rs
Rs is the symbol that represents the reflected "s" polarization.
Scratch
Scratch: Also called a gouge or dig. This artifact is defined as a long, transparent, linear defect that affects the contrast performance. It is typically specified by the width and the length of the artifact.
Skew-ray
Skew-ray is defined as 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
Spot: This artifact defined as 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.
Tp
Tp is the symbol that represents the transmitted or "p" polarization
Ts
Ts is the symbol that represents the transmitted "s" polarization.
Wire Height
Wire Height: This term is defined as 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.
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.
A wire-grid polarizer converts an unpolarized beam into one with a single linear polarization. 
WAVELENGTH
The 'wavelength ' is the distance between repeating units of a wave pattern. It is commonly designated by the Greek letter lambda (λ).
In a sine wave, the wavelength is the distance between the midpoints of the wave:
Image:Wavelength.svg
The x axis represents distance, and I would be some varying quantity at a given point in time as a function of x.
 
 
   
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