Diffraction Grating Calculator

Calculate diffraction angles for each order using d sin(θ) = mλ. Find the maximum observable order and angular dispersion.

Inputs

Wavelength

Grating Lines

lines/mm

Diffraction Order (m)

Tab to move between fields

Results

Diffraction Angle

19.269

Grating Spacing1.67 μm

Max Observable Order3

Angular Dispersion635,606.06 rad/m

How to Use This Calculator

Enter Wavelength, Grating Lines, and Diffraction Order (m).
Review the Diffraction Angle (°) result.
Use Grating Spacing (μm) and Max Observable Order to inform your decision.
Use the chart to visualize the results and explore different scenarios by adjusting inputs.

What each input means

Wavelength: Wavelength of the incident light in nanometers. Visible light: 380–700 nm.
Grating Lines: Number of slits per millimeter on the grating. Typical gratings: 300–1200 lines/mm.
Diffraction Order (m): The order of the diffraction maximum. First order (m=1) is typically the brightest.

How this is calculated

Worked example, using the default values

Identify Input Parameters
Wavelength = 550, Grating Lines = 600, Diffraction Order (m) = 1 = 3 input(s) provided
Calculate Diffraction Angle
19.269 = 19.269
Calculate Grating Spacing
Grating Spacing = d
1.667 = 1.667
Calculate Max Observable Order
Max Observable Order
3 = 3

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