|
Colorado
Texas
Florida
Louisiana
New York
Missouri
Wisconsin
|
Top "Technology Channel" News Story:
Laser
Optics and
Femtosecond Fiber Lasers in Relation to Photonics
by Nicole and Justin Richards
In physics, a physical
constant is a physical quantity that is generally believed to be both
universal in nature and constant in time. It can be contrasted with a
mathematical constant, which is a fixed numerical value but does not
directly involve any physical measurement.
There are many physical constants in science, some of the most widely
recognized being the rationalized Planck's constant h, the gravitational
constant G, the speed of light in the vacuum c, the electric constant
ε0, and the elementary charge e. Physical constants can take many
dimensional forms: the speed of light signifies a maximum speed limit of
the universe and is expressed dimensionally as length divided by time;
while the fine-structure constant α, which characterizes the strength of
the electromagnetic interaction, is dimensionless.
--Wikipedia
 Glossary
A NIST Physical Constants Reference Source:
Reference
Source
Abbe number: or Abbe factor or Abbe
constant, the ratio of refractive index to dispersion; Vd = (nd-1)/(nf-nc)
where Vd = Abbe number at wavelength, nf = index of refraction at 486
nm, nc = index of refraction at 656 nm, and nd = index of refraction at
wavelength.
achromat: a lens designed for broadband applications consisting
of two or more lens elements composed of discrete glass materials which
is corrected for Chromatic Aberration with respect to two wavelengths
(normally blue and red).
achromatic lens: a lens designed for broadband applications
consisting of two or more lens elements composed of discrete glass
materials which is corrected for Chromatic Aberration with respect to
two wavelengths (normally blue and red).
achromatic waveplate: a broadband waveplate designed using two
different substrate materials with compensating retardances and
dispersions of retardance
angle of incidence (AOI): the angle that an incident ray makes
with the normal to the surface
angstrom: equals 10^-10 meters = 0.1 nanometers, a unit of length
but not an SI unit
anisotropic: having a physical property that is different when
measured in two different directions.
antireflection coating (AR): single layer, V-coat or broadband (BBAR)
dielectric coatings to reduce transmission loss, minimize stray light
and prevent back reflections
aplanat: A lens designed to minimize two monochromatic (single
wavelength) wavefront errors called Spherical Aberration and Coma. Often
called Fraunhofer lenses.
aplanatic lens: A lens designed to minimize two monochromatic
(single wavelength) wavefront errors called Spherical Aberration and
Coma. Often called Fraunhofer lenses.
apochromatic lens: a multi-element lens which minimizes both
Spherical aberration and Chromatic aberration at three wavelengths
attenuator: an optic or electrical device which reduces the
intensity of a beam a fixed or adjustable amount via absorption,
scattering or reflection
attosecond (as): equals 10^-18 seconds
bandpass filter: a filter that passes frequencies within a
certain wavelength range and blocks frequencies outside that range
BBAR: broadband anti-reflection coating (multi-layer dielectric)
beam deviation: the difference in angle of an incoming beam to a
transmitted, reflected or refracted beam through an optic, particularly
relevant to cubes and dispersive prisms
beam dump: a device to trap or dump unwanted light radiation via
scattering or absorption
beam expander: a multi-element lens system used to expand (or in
reverse, reduce) beam diameter
beamsplitter cube: two right angle prisms where the hypotenuse of
one of the prisms is coated with a semi-reflective polarizer or
beamsplitter coating; the two prisms are cemented, bonded or contacted
together to form a cube.
beamsplitter plate: A durable all-dielectric mutilayer coating
used to either split or combine a laser beam, usually at 45 degrees
bi-axial crystal: a birefringent crystal having two axes with
different indices of refraction
bi-concave: a singlet lens with both surfaces concave; R1 may or
may not equal R2
bi-convex: a singlet lens with both surfaces convex; R1 may or
may not equal R2
birefringence: the splitting of a light wave into two waves by an
optically anisotropic medium such as calcite or quartz. Also called
double refraction.
birefringent: the index of refraction differs along the fast &
slow axes, affecting the phase shift of the orthogonally polarized
linear polarization states differently. Some birefringent materials are
crystal quartz, mica, calcite, ice, sodium nitrate, lithium niobate,
rutile, magnesium fluoride and sapphire
BK7: borosilicate crown glass which is transmissive in the
visible and near-infrared wavelength regions
Brewsters angle: A) the angle of incidence at which the
reflectance of the TM-polarized (whose electric-field vector lies in the
plane of the direction of propagation and the normal to the surface)
light is zero.
B) the angle at which the fresnel reflectivity of P-polarized light
drops to zero, B = tan-1 (n2/n1)
broadband: a wide spectral bandwidth
CADB: Chemically Activated Direct Bonding - epoxy free optical
bond
calcite: (CaCO3) a soft, birefringent crystal with broadband
transmission through the visible and near-infrared; used in polarizers
Chromatic aberration: a wavefront error produced by dispersion
causing different wavelengths to have different focal points. By using
separate glass types (crown & flint) for the positive and negative lens
elements, the dispersion of each is compensated for by the other,
thereby minimizing the total effect.
circular polarization: When one component of linear electric
field is retarded by l/4 with respect to the other orthogonal component;
this is done by aligning linearly polarized light midway between the
slow and fast axes of a quarter waveplate.
clear aperture (CA): The opening through which light can pass
unobstructed.
The central area over which the optical specifications apply
coherent: when light waves have a constant phase relationship
over time, like a laser beam. See temporal coherence and spatial
coherence.
cold mirror: a filter used to reflect visible and transmit
near-infrared energy, for temperature control
collimated light: when each ray within a beam is parallel to
every other, neither converging nor diverging
Coma: an off-axis non-symmetric wavefront distortion which
increases linearly with field angle or distance from the principal axis
compound waveplate: a zero order waveplate constructed using two
multiple order waveplates aligned with their axes crossed and designed
so that they differ in thickness by the exact amount necessary for a
true zero order waveplate; they can be optically contacted, cemented or
air-spaced
concave: curved inward; the edge of a concave lens is thicker
than the center
concentricty: the deviation between the optical and mechanical
axes of a lens, often measured by maximum edge thickness variation
contacted: the process of adhering or connecting two clean, flat
surfaces without the use of epoxy or cement
converging lens: A plano-convex, bi-convex or meniscus lens that
converges an incident bundle of rays to a focus. (positive lens)
convex: curved outward, the center of a convex lens is thicker
than the edge
critical angle: C(l) = arcsin(1/n) where n is the index of
refraction of the glass at wavelength l. The angle of incidence at the
interface between a denser and less dense medium at which light is
refracted along the interface; when the critical angle is exceeded, the
light is totally internally reflected.
crown glass: borosilicate glass used in the visible and
near-infrared wavelength regions (BK7)
crystal quartz: a positive uniaxial birefringent single crystal
commonly used for waveplates and optical rotators
cylindrical lens: The curve on a cylindrical lens is cylindrical
in shape, resulting in a focal line instead of a point. Standard thin
lens formulas apply, but in one dimension only
dichroic: the reflection and transmission of light as a function
of wavelength. A dichroic mirror reflects one wavelength and transmits
another.
dielectric: non-conducting, or non-metallic, as in a dielectric
coating
diffraction limited: an optic or optical system where the quality
of the optical image produced is at the theoretical limit of diffraction
theory
dig: a defect on the surface of an optic as defined in average diameter
in 1/100 of a millimeter
diode laser: also called a light-emitting diode (LED) or semiconductor
laser, available in wavelengths from the UV through the NIR
dispersing prism: a prism used to separate white light into its
component colors, or to separate two laser wavelengths traveling along
the same beampath
dispersion: the variation of refractive index with wavelength
diverging lens: A plano-concave, bi-concave or meniscus lens that causes
parallel light rays to diverge or spread out; the edge of a negative
lens is always thicker than the center. (negative lens)
double-V or dual-V: a dual wavelength multi-layer dielectric
anti-reflection coating with a spectral trace resembling two "V" shapes,
usually designed for harmonic wavelengths
doublet lens: a multi-element lens having two elements, either cemented
or air-spaced
equi-concave: a lens with both surfaces concave and R1 = R2
equi-convex: a lens with both surfaces convex and R1 = R2
etalon: Fabry perot etalon - flat, plane-parallel window with a
dielectric partially-reflecting coating applied to both sides. The
transmission bandwidth is determined by the finesse. The separation of
the pass-bands is determined by the free spectral range (FSR)
excimer lasers: argon fluoride (ARF, 193nm), krypton fluoride (KRF,
248nm), xenon chloride (XECL, 308nm), xenon fluoride (XEF, 351-353nm)
extinction ratio: in a polarizer, the ratio of the optical power in the
desired transmitted polarization to that in the blocked polarization
Plate Polarizers
extraordinary axis: The principal axis in birefringent materials with
the higher index of refraction; called the slow axis because light
travels slower along that direction
f-number: f/# = f/D The ratio of the focal length of the lens to its
clear aperture (D); defines the speed of a lens or lens system.
Fabry Perot etalon: A flat, plane-parallel window with a dielectric
partially-reflecting coating applied to both sides. The transmission
bandwidth is determined by the finesse. The separation of the pass-bands
is determined by the free spectral range (FSR)
far infrared (FIR): The wavelength region of the electromagnetic
spectrum ranging from approximately 8um to 14um
fast axis: The principal axis in birefringent materials with the lower
index of refraction; called the fast axis because light travels faster
along that direction (ordinary axis)
femtosecond (fs): equals 10^-15 seconds
filter: an optical element, usually flat, used to transmit some wavelength(s) of light while blocking or attenuating others. Examples
are bandpass, neutral desity or notch filter.
finesse: the ratio of the free spectral range of an etalon to its full
width at half maximum of its transmission peak; determines the
transmission bandwidth of a solid etalon.
finesse=(R)/(1-R) where R is the reflectivity of the surface of the
etalon
first order waveplate: Often called true zero order waveplates, they can
be made as single plates around 100 microns thick or adhered to a
thicker host substrate via optical contacting or optical cement.
Manufactured for applications requiring increased bandwidth, field of
view or thermal stability
flint glass: used in the visible and near-infrared spectral regions,
flint glass is softer than crown glass, more dispersive and usually has
a higher refractive index and low Abbe number
fluorescence: The emission of light radiation at a longer wavelengths by
a material as a result of the absorption of light at shorter wavelengths
Fraunhofer lens: A lens designed to minimize two monochromatic (single
wavelength) wavefront errors called Spherical Aberration and Coma. (aplanat)
free spectral range (FSR): the spacing (usually given in frequency)
between transmission peaks of an etalon FSR=c/(2nl) where c is the speed
of light, n is the index of refraction of the etalon, and l is the
thickness of the etalon.
fresnel reflection: the reflectance in air (n ~ 1.0) off an uncoated
glass surface at normal incidence: R = ((n-1)/(n+1))2 where n is the
refractive index of the substrate material
Fresnel Rhomb: An alternative to the plate retarder these prisms utilize
total internal reflection (TIR) to produce a phase delay between the S
and P polarization components which is both spectrally and thermally
stable.
fused silica: an amorphous form of silicon dioxide with very high laser
damage thresholds as well as high transmittance throughout the UV,
visible and near-infrared wavelength regions
FWHM: full width half max of an etalon pass band; equals the free
spectral range (FSR) divided by the finesse (F)
galilean telescope: a refracting telescope or beam expander designed
using a positive and negative lens, the expansion ratio equals the ratio
of their respective focal lengths
gas lasers: argon-ion (488-515nm), copper vapor (511/578nm), helium
cadmium (442nm), helium neon (633nm), iodine (1315nm), nitrogen (337nm)
Gimbal mount: a kinematically-correct mount for precision rotation or
adjustment of an optic without translation of the center point
half waveplate: the difference in phase introduced between the two
polarization components equals a half of a wave; also called a l/2
retardation plate. Half waveplates rotate the polarization of linearly
polarized light to twice the angle between the incident plane of
polarization and the fast optical axis.
harmonic separator: a dichroic mirror specifically designed for the
harmonics of Nd:YAG or other laser sources
homogeneity: the level of sameness in material quality and optical
property regardless of the direction or location within the bulk
material
hot mirror: a filter used to transmit visible and reflect near-infrared
energy, for temperature control
hypotenuse: the surface of a right angle prism (RAP) opposite the right
angle, the longest of the 3 polished sides
index of refraction: the ratio of the speed of light in a vacuum (c) to
the speed of light in a given material at a specified wavelength. The
index in a vacuum = 1.0
infrasil: low OH content fused quartz produced by electrically fusing
quartz crystal; sometimes called IR grade fused silica
interferometer: an instrument that uses the interference of lightwaves
to measure surface flatness, parallelism or radius. Three common types
are Fizeau, Michelson and Twyman-Green.
jitter: random variation in the timing of a signal
joule (J): a unit of energy equaling 1 watt/second or 10^7 ergs
laser optics: See
laser: light amplification by stimulated emission of radiation; the
laser cavity is a source of monochromatic, coherent, reasonably
collimated light from a medium (crystal, glass, liquid, dye or gas),
within resonator mirrors and excitation source (light or electrical
discharge)
laser line filter: high transmission of a laser line with blocking of
all other wavelengths, also called "clean up filters"
Laurent formula: the dispersion equation used for crystal quartz
leaky polarizer: a beamsplitter cube with equal optical pathlengths
coated for polarization-sensitive beam sampling
lens: a transmissive optic with one or more elements having at least one
curved surface each which is used to converge, diverge or collimate a
beam of light
LiDAR: an acronym for Light Detection And Ranging which is a method for
detecting distant objects and determining their position, velocity, or
other characteristics by analysis of pulsed laser light that is
reflected from their surfaces.
linear polarization: when the electric field is always parallel to the x
or y-direction, or some angle in between.
linear polarizer: a device that creates linear polarization from an
arbitrary input by removing the component orthogonal to the selected
state via reflection, refraction or absorption
long wave pass: a filter or dichroic mirror which transmits longer
wavelengths and reflects or absorbs a shorter wavelength or wavelength
region
meniscus lens: a crescent-shaped singlet lens designed to minimize
spherical aberration; one surface is convex and the other concave
meter: length of the path travelled by light in vacuum during a time
interval of 1/299,792,458 of a second
mica: a birefringent crystal used in thin sheets, sometimes cemented
between glass substrates and used as waveplates or low-cost optical
retarders
micron (um): also called a micro-meter, a micron equals 10^-6 meters =
1000 nanometers
microsecond (us): equals 10^-6 seconds
mid-infrared (MIR): The wavelength region of the electromagnetic
spectrum ranging from approximately 3um to 8um
mirror: also called a high-reflector, a flat or curved optical element
coated with a dielectric stack or metallic material to reflect light
monochromatic: light consisting of a single wavelength or color, or very
narrow band of wavelengths (< 0.1nm)
multiple order waveplate: a single element waveplate with order m > 0,
generally considered inexpensive, high damage threshhold retarders for
single wavelength applications
nanometer (nm): also called a millimicron, a nanometer = 10^-9 meters =
10 angstroms
nanosecond (ns): equals 10^-9 seconds
near-infrared (NIR): The wavelength region of the electromagnetic
spectrum ranging from approximately 700nm to 3000nm
negative lens: a plano-concave, bi-concave or meniscus lens that causes
parallel light rays to diverge or spread out; the edge of a negative
lens is always thicker than the center.
neutral density filter: an absorptive or metallic-coated glass filter
providing equal attenuation across and spectral bandwidth, can be
constant, lineraly variable or step variable in design
non-polarizer: plate or cube beamsplitter coated such that (typically)
Rs-Rp < 3-5%
normal axis: the axis that is perpendicular to or forms right angles
with the surface or plane of incidence
notch filter: maximum blocking of a laser line, for Raman and
fluorescence applications
numerical aperture (NA): the sine of the angle made between the marginal
ray of a lens and the optic axis with respect to an object or image
point, multiplied by the refractive index of the incident media, NA =
1/(2 x f/#) where f/# = f/D
optical contact: the process of adhering, bonding or connecting two
clean, flat surfaces without the use of epoxy or cement
optical density: a measure of transmittance through a substrate or
coating, OD = log (1/T) where T is transmittance
ordinary axis: the principal axis in birefringent materials with the
lower index of refraction; called the fast axis because light travels
faster along that direction
output coupler: also called a partial reflector, an all-dielectric
multi-layer coating used to split a laser beam, usually at normal
incidence (0 degrees)
P-polarization: parallel to the plane of incidence, often called
transverse-magnetic (TM) or horizontally polarized because the electric
field direction of the wave is in the horizontal plane along the
direction of propagation
partial reflector: also called an output coupler, an all-dielectric
multi-layer coating used to split a laser beam, usually at normal
incidence (0 degrees)
pellicle: a very thin, delicate membrane streched over a support frame
or cemented to a ring mount, typically used as a 45deg beamsplitter
(coated or uncoated) with no change in optical path length, no 2nd
surface reflections and no chromatic aberration
photon: a quantum unit of electromagnetic energy of a single wavelength,
direction and polarization which acts as both a wave and a particle of
light
Plancks constant: h=6.626 x 10-27 ergs
plane polarization: when the electric field is always parallel to the x
or y-direction, or some angle in between.
plano-concave: A negative lens with one flat (plano) surface and one
concave surface
plano-convex: A positive lens with one flat (plano) surface and one
convex surface
polarization: the direction in which the electric field of a light wave
oscillates
polarizer: a component which outputs polarized light from input
unpolarized light via selective absorption, refraction or transmission
of a particular polarized state
polarizing beamsplitter cube: cubes used to split a laser beam into two
orthogonally polarized components; P-polarization is transmitted while
S-polarization is reflected at 90. Polarizer cubes utilize a dielectric
coating at the internal cemented interface, external surfaces are
anti-reflection coated
polymer waveplate: an alternative to crystal quartz or achromatic plate
retarders for low energy visible and near-infrared applications, Polymer
is fairly impervious to changes in wavelength or angle of incidence
porro prism: a type of reflection prism used to rotate an image by 180
degrees and in the opposite direction from its entrance point
positive lens: A plano-convex, bi-convex or meniscus lens that converges
an incident bundle of rays to a focus
prism: an optic with at least 2 polished non-parallel surfaces through
which light is reflected or refracted
quarter waveplate: When the difference in phase introduced between the
two polarization components equals a quarter of a wave. Also called a
l/4 retardation plate
radius of curvature (ROC): the radius of the sphere coincident with the
optical surface
reflected wavefront distortion (RWD): the amount of deviation from an
ideal surface, in terms of waves or fringes peak-to-valley (p-v) or RMS;
twice the surface figure
refractive index: the ratio of the speed of light in a vacuum (c) to the
speed of light in a given material. The index in a vacuum = 1.0
retroreflector: a prism which reflects the light back parallel to the
incoming beam but in the opposite direction
right angle prism: a 45-45-90 prism which can be used as a
retroreflector or a bending prism
S-polarization: perpendicular to the plane of incidence (from senkrecht,
the German word for perpendicular), also called transverse-electric (TE)
or vertically polarized because the electric field direction of the wave
is perpendicular to the horizontal plane along the direction of
propagation.
sagitta: the depth of a curve as measured from the chord, sag = R -
sqrrt (R^2 - r^2) where R is radius of curvature and r is the
half-diameter of a lens or curved substrate
scratch/dig: a measure of visible surface defects as defined by MilSpec:
MIL-0-13830, usually denoted as two numbers where the first is the
visbility of scratches and the second of digs or small pits
Sellmeier equation: the dispersion equation used for most optical glass
types (not crystal quartz)
short wave pass: a filter or dichroic mirror which transmits shorter
wavelengths and reflects or absorbs a higher wavelength or wavelength
region
slow axis: The principal axis in birefringent materials with the higher
index of refraction; called the slow axis because light travels slower
along that direction
Snells law: determines the angle of refracted light an an interface of
non-equal indices for any theta > 0deg such that the ratio of the sines
of the angles are constant (n2/n1); n1sin(theta1) = n2sin(theta2)
solid state lasers: ruby (694nm), alexandrite (720-780nm), Erbium:glass
(1540nm)
spherical aberration: an axially symmetric wavefront error that occurs
when rays from a point on the axis passing through the outer zones of
the lens focus at a different distance from the lens than rays passing
through the central zone
suprasil: a type of fused silica with high chemical purity, high UV
transmittance and minimal fluorescence
surface figure: the deviation from an ideal optical surface, in terms of
waves or fringes peak-to-valley (p-v) or RMS
surface flatness: the amount that an optical surface deviates from a
perfect plane
surface quality: the level of defects that can be visually observed on
the surface of an optic and usually given by MIL-0-13830A where the
first number is the visibility of the scratches and the second of digs
or small pits. (scratch-dig)
surface roughness: the amount the surface of an optic differs from
perfectly smooth, and is usually denoted as a root mean square (rms)
value in Angstroms
Telcordia: formerly Bellcore, Telcordia qualification is a highly
rigorous standard that ensures telecommunication components and
instruments perform as required when field deployed. Qualification
includes storage and operating temperature, thermal cycling, vibration
and shock
tomography: any of several techniques for making detailed images of a
predetermined plane section of a solid object while blurring out the
images of other planes
total internal reflection (TIR): The reflection that occurs within a
substance when the angle of incidence of light at the boundary surface
is greater than the critical angle
transmitted wavefront (TWD): the amount of deviation from an ideal or
input beam through an optic, in terms of waves or fringes peak-to-valley
(p-v) or RMS
true zero order waveplate: Often called first order waveplates, they can
be made as single plates around 100 microns thick or adhered to a
thicker host substrate via optical contacting or optical cement;
manufactured for applications requiring increased bandwidth, field of
view or thermal stability
ultraviolet (UV): The wavelength region of the electromagnetic spectrum
ranging from approximately 150nm to 400nm
unpolarized: A ray of light in which the direction of polarization
varies randomly
V-coat: a narrowband multi-layer dielectric anti-reflection coating with
a spectral trace resembling a "V" shape
VIPA: Virtually Imaged Phased Array - an etalon that is used off-axis
(tilted) which has a high reflective coating on one side and a partial
reflector on the other, resulting in large angular dispersion.
visible (VIS): The wavelength region of the electromagnetic spectrum
ranging from approximately 400nm to 700nm
waveplate: a birefringent optical device that alters the polarization
state of a light wave travelling through it, depending on the thickness
of the material and wavelength of light; also called a retardation plate
or optical retarder
wedge: the parallelism or angle between the two surfaces of an optical
component
zero order waveplate: see compound waveplate or true zero order
waveplate
Economically important
applications for semiconductor photonic devices include optical data
recording, fiber optic telecommunications, laser printing (based on
xerography), femtosecond lasers, displays, and optical pumping of
high-power lasers.
http://wallstreet.part.to/technology/optics/
http://wallstreet.part.to/technology/lasers/
|
|
|
