Raman Tools

Spectral Resolution Calculator

Will your spectrometer resolve two close peaks? Resolution depends on the diffraction grating, focal length, and slit width. Enter the parameters, and we will calculate the approximate resolution in nm and cm⁻¹ for your laser — plus the linear dispersion of the detector.

Spectrometer

Grating density (lines/mm) Focal length (mm) Slit width (µm) Laser wavelength (nm)

Formulas and assumptions

Reciprocal linear dispersion: RLD [nm/mm] = 10⁶ / (m · g · f)
Resolution (slit): δλ [nm] = RLD · slit [mm] = 1000 · w[µm] / (m · g · f)
In wavenumbers: δν̃ [cm⁻¹] = 10⁷ · δλ / λ²

Model for the first order (m = 1) and small angles (cos β ≈ 1), with resolution limited by slit width (g — lines/mm, f — focal length in mm). In practice, detector pixel size and aberrations add to the result — actual resolution may be slightly worse. Narrower slit = better resolution, but less light (longer measurement — see SNR calculator).

Approximate result — full optical system specification is required for an accurate value.

Have a sample you don’t want to guess about?

We conduct feasibility studies even on the most challenging samples — on your material, at your site. Leave your contact, and we will review your case and tell you directly whether Spectrally can measure it.

Write to us and learn more

Aleksandra Łukasiewicz

Head of International Sales

+48 512 554 952 · +1 (804) 593-0282
a.lukasiewicz@gekkophotonics.com

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