Spectral resolution

Spectral resolution measures an instrument’s ability to distinguish nearby wavelengths. It is commonly expressed as resolving power, the wavelength divided by the smallest distinguishable wavelength separation.

Resolving power: The ratio of a wavelength to the smallest wavelength separation an instrument can distinguish. This ratio is the standard quantitative expression of spectral resolution.
Astronomical spectroscopy: The study of celestial objects by measuring their light as a function of wavelength. Resolving stellar and galactic lines reveals motion, composition, and physical conditions.
Spectral bandwidth: The range of wavelengths contained in a signal or passed by an optical system. Bandwidth describes a wavelength range; resolution describes distinguishable detail within it.
Wavelength: The spatial period of a wave, measured between corresponding points in successive cycles. Spectral resolution is defined through separations along the wavelength axis.
Optical spectroscopy: The measurement and interpretation of light interacting with matter across optical wavelengths. Spectral resolution is a core performance measure for optical spectrometers.
Instrumental line shape: The profile produced by an instrument when measuring an ideally narrow spectral line. Its width and shape determine how closely spaced spectral lines appear.
Raman spectroscopy: A technique that identifies molecular vibrations through wavelength shifts in scattered light. Closely spaced Raman bands can require high spectral resolution for reliable identification.
Wavelength accuracy: How closely a measured wavelength agrees with its true value. An instrument can locate a line accurately without resolving two nearby lines.
Frequency: The number of wave cycles passing a point per unit time. Spectra may be represented in frequency, where resolving power uses frequency separation.
Nyquist–Shannon sampling theorem: A theorem stating conditions for reconstructing a band-limited signal from discrete samples. It constrains how finely a resolved spectrum must be sampled digitally.

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