Question 1

Absorption (optical)

Accepted Answer

How an optical component captures (some of a) light ray's energy, transforming electromagnetic energy into internal energy. Results in a reduction of a system's optical throughput.

Question 2

Accelerating voltage

Accepted Answer

A microscope parameter that describes the energy of the incident electron (beam).
Usually, it is presented in Voltage (kV) or Energy (keV).

Question 3

Angle-resolved image

Accepted Answer

A 2D data set (image) where each pixel describes a unique emission direction (see Emission Patterns).

Question 4

Array detector

Accepted Answer

A pixelated detector that is useful to acquire wavelength-resolved spectra and/or an angle-resolved image in a single frame.

Question 5

Band gap

Accepted Answer

An energy range in a solid where no electron states can exist. Band gaps can be found in insulators and semiconductors. In graphs of the electronic band structure of solids, the band gap is the energy difference (in electron volts) between the valence band's top and the conduction band's bottom.

Question 6

Band pass

Accepted Answer

Describes a range of wavelengths (e.g., a 50 nm band pass corresponds to λ ± 25 nm).

Question 7

Band-to-band (radiative) recombination

Accepted Answer

The process of electrons jumping down from the conduction band to the valence band in a radiative manner.

Question 8

Binning

Accepted Answer

A method of reading out the information captured in a pixelated detector, e.g., a CCD in which a group of pixels is read out together, reduces the readout noise.

Question 9

Blaze wavelength

Accepted Answer

The wavelength that a diffraction grating is designed to operate at with the smallest losses.

Question 10

Carrier generation

Accepted Answer

A mechanism by which solids may absorb energy from the incident electron beam in which free carriers are generated as electrons exit from the valence band to the conduction band.

Question 11

Cathodoluminescence (CL)

Accepted Answer

The emission of photons from a material when struck by a high-energy electron beam.

Question 12

Central wavelength

Accepted Answer

The wavelength that passes through an infinitesimally small exit slit. Also used to indicate the middle of the range wavelength in a wavelength-resolved spectrum.

Question 13

Charge-coupled device (CCD)

Accepted Answer

An imaging device where the charge is moved to an area within the same device where it can be digitized and is used for acquiring spectroscopic data in parallel.

Question 14

Chromatic aberration

Accepted Answer

The tendency of a lens to focus light of different wavelengths to different points.

Question 15

Collection mirror

Accepted Answer

Optical component used to collect photons emitted from a sample.

Question 16

Collimated beam

Accepted Answer

A beam of light in which the light travels in parallel lines.

Question 17

Color center

Accepted Answer

An impurity or defect center that gives rise to visible luminescence from insulators via a mid-gap energy state.

Question 18

Dark current

Accepted Answer

Thermally generated charges in the silicon sensor of a camera.

Question 19

Dark noise

Accepted Answer

Statistical variation in the number of electrons thermally generated within the pixel in a photon-independent fashion; the electron equivalent of photon shot noise. Dark noise = √(dark current * integration time).

Question 20

Diffraction grating

Accepted Answer

An optical element used in a spectrometer to disperse light by wavelength.

Question 21

Dispersion

Accepted Answer

The separation of light according to wavelength.

Question 22

Electroluminescence (EL)

Accepted Answer

The transformation of electrical energy into electromagnetic radiation.

Question 23

Electromagnetic spectrum

Accepted Answer

The electromagnetic spectrum is the range of frequencies of electromagnetic radiation and their respective wavelengths and photon energies.

Question 24

Electron probe microanalyzer (EPMA)

Accepted Answer

An analytical tool used to determine the chemical composition of small volumes of solid materials; works similar to a scanning electron microscope.

Question 25

Electron-hole pair

Accepted Answer

The free carriers created when an electron in the valence band is promoted to the conduction band (leaving behind a hole).

Question 26

Emission pattern

Accepted Answer

Representation of the directional (angular) dependence of the luminescence, typically presented as a 2D plot in polar coordinates.

Question 27

Energy

Accepted Answer

Property of the emitted light. Related to wavelength by E = hc/λ, where h is Planck's constant and c the speed of light.

Question 28

Entrance slit

Accepted Answer

Component of a spectrometer that determines the spectral resolution and throughput (see Exit slit).

Question 29

Exciton

Accepted Answer

An exciton is a bound state of an electron and an electron-hole which are attracted to each other by the electrostatic Coulomb force.

Question 30

Exit slit

Accepted Answer

Component of a spectrometer that determines the spectral resolution and throughput (see Entrance slit).

Question 31

Field of view

Accepted Answer

The observable area via an optical device; sometimes described by spatial extent (meters) or angular range.

Question 32

Filter housing

Accepted Answer

A component used to insert an optical filter.

Question 33

Free carriers

Accepted Answer

Electrical charge carriers (electrons and/or holes) which are free to move within the conduction energy band.

Question 34

Free-space coupling

Accepted Answer

An optical system based on open beams and reflective surfaces rather than image conduits such as optical fibers.

Question 35

Generation rate

Accepted Answer

The rate at which free carriers are generated (#/s).

Question 36

Generation volume

Accepted Answer

The region in a sample in which the signals being monitored in an SEM are formed.

Question 37

Gruen range

Accepted Answer

The stopping range of incident electrons within the material; described by a mathematical model.

Question 38

Hot spot

Accepted Answer

The region from which maximum optical collection efficiency is achieved when the specimen is at the focal point of the collection mirror.

Question 39

Hyperspectral image

Accepted Answer

See Spectrum image.

Question 40

Image contrast

Accepted Answer

The difference in the color and/or brightness of an object compared to the background within a field of view.

Question 41

Infrared

Accepted Answer

A part of the electromagnetic spectrum at longer wavelengths than visible by the human eye (~700 nm – 1 mm).

Question 42

Lateral focal range

Accepted Answer

Describes the geometric extent of the object image that can be viewed by an optical system without vignetting.

Question 43

Longpass filter

Accepted Answer

An optical filter that transmits wavelengths longer than a defined wavelength.

Question 44

Luminescence

Accepted Answer

The transformation of a diverse range of energies into light (electromagnetic radiation)..

Question 45

Majority carrier

Accepted Answer

The more abundant charge carriers in a semiconductor primarily responsible for current transport.

Question 46

Minority carrier

Accepted Answer

The less abundant charge carriers in a semiconductor.

Question 47

Minority carrier lifetime

Accepted Answer

The average time it takes for a minority carrier to recombine.

Question 48

Monochromatic

Accepted Answer

A single wavelength (color) of light.

Question 49

Monochromator

Accepted Answer

See Spectrometer.

Question 50

Multiple linear least squares (MLLS)

Accepted Answer

MLLS fitting is a method to fit a number of reference spectra and/or models to a spectrum.

Question 51

Non-linear least squared (NLLS)

Accepted Answer

NLLS is fitting models to spectral features to quantify the spectral peak properties.

Question 52

Non-radiative recombination

Accepted Answer

When an electron in the conduction band recombines with a hole in the valence band and the excess energy is emitted in the form of a phonons rather than a photon.

Question 53

Numerical aperture (NA)

Accepted Answer

A dimensionless number that characterizes the range of angles over which an optical system can accept (or emit) light.

Question 54

Optical axis

Accepted Answer

An imaginary line that defines the path along which light propagates through an optical system..

Question 55

Optical cathodoluminescence

Accepted Answer

An attachment for an optical microscope that employs a hot cathode flood gun to generate an electron source for cathodoluminescence investigation.

Question 56

Optical fiber

Accepted Answer

A thin flexible fiber with a glass core through which light signals can be sent with very little loss of strength.

Question 57

Optical filter

Accepted Answer

An optical element that selectively transmits light of different wavelengths.

Question 58

Panchromatic

Accepted Answer

See Unfiltered.

Question 59

Parabolic mirror

Accepted Answer

An optical component designed to collimate light emitted from a Lambertian source at the focal point of the parabola.

Question 60

ParaCL

Accepted Answer

Description of a spectrum acquired using an array detector.

Question 61

Photoluminescence (PL)

Accepted Answer

Light emission from any form of matter after the absorption of photons (electromagnetic radiation).

Question 62

Photomultiplier tube (PMT)

Accepted Answer

Device used to detect light by converting an incident photon into a pulse of electrons.

Question 63

Photon

Accepted Answer

The basic unit of light.

Question 64

Photon counting

Accepted Answer

Signal processing method in which individual photons are counted (photons/s).