Diffraction Grating Angle Calculator
Calculate normal-incidence diffraction angle, angular dispersion and ideal grating resolving power.
YOUR CALCULATION
Result
—
Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
Use normal incidence so the grating equation has one signed diffracted angle; differentiate it for angular dispersion.
sinθ=mλ/d; d=1/(grooves per meter); resolving power=|m|×illuminated whole grooves
Worked example
550 nm and 600 grooves/mm in first order give sinθ=0.33 and angle about 19.2687755°. A 10 mm illuminated width spans 6000 whole grooves.
Assumptions and input details
Ideal evenly spaced grooves and normal incidence. Require |mλ/d|<1; grazing/evanescent orders are rejected. Resolving power is an ideal diffraction limit, not instrument resolution, efficiency, blaze response or manufacturing tolerance.
References: Edmund Optics: grating equation
Unit definitions
Unit selection is independent of language. Each selector contains only units for its physical quantity. Calculations use defined base units internally.
Choose from 23 length definitions, including explicitly labelled regional measures. Area conversions square the length factor; geometric volumes cube it.
Regional measures are not interchangeable merely because their names look similar. This is a documented selection, not a claim to include every historical unit.
NIST measurement tables · Japanese traditional units · Mainland China and Hong Kong unit distinctions
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
Is my input uploaded?
The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
Calculate wave speed, frequency or wavelength from the other two. Convert units, find the period and view an illustrative normalized wave.
Convert vacuum wavelength, frequency and energy per photon using the exact SI defining constants. Select independent input and output units.
Find reflected and refracted ray directions from incidence angle and two refractive indices. Detect total internal reflection and show the critical angle.
Reserved advertising space.