Angle-Resolved
Overview
In the angle-resolved cathodoluminescence (ARCL) mode, the direction in which a photon is emitted is determined. An objective lens or, more commonly, a collection mirror projects an image of the emitted light onto a pixelated detector, e.g., a camera. When an appropriate optical system is used, each pixel in the captured image corresponds to a unique emission direction from the specimen. The raw image is typically transformed into polar coordinates for display and interpretation.
The result of an angle-resolved measurement contains no wavelength or polarization information unless additional dispersion filtering is used (e.g., wavelength- and angle-resolved mode).
Angle-filtered information may be captured using an iris or a pinhole to select a specific (range of) angle(s). However, this particular acquisition mode's low resolution and highly serial nature have limited its usefulness.
Data collection
Emission pattern or angle-resolved emission pattern
The emission pattern is a plot of the direction in which photons are emitted from a specimen. It is typically presented in polar coordinates, where the emission direction is described by the azimuthal and zenith angles. A single emission pattern may be captured from a point or region of the sample exposed to the electron beam of the electron microscope.
Emission pattern image or angle-resolved spectrum image
The electron beam is scanned across the specimen surface, and an emission pattern is recorded at each location, creating a hyperspectral (4D) data construct.
Applications
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Uses
