How to use the diffraction grating calculator
Find the angle of a diffraction order. Enter lines per mm, wavelength, order in the fields above; the angle is computed instantly and plotted on the chart so you can see how the answer changes.
Formula
Variables
- N — Lines per mm
- lam — Wavelength (nm)
- m — Order
Worked example
With lines per mm = 600, wavelength = 550 nm, order = 1, the calculator gives angle ≈ 19.26878 °.
Frequently asked questions
What is the formula for the diffraction grating calculation?
Angle (°) = asin(m × lam × 1e-9 × N × 1000). Here N is lines per mm, lam is wavelength (nm), m is order.
What inputs do I need for the diffraction grating calculator?
You need lines per mm, wavelength in nm, order. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use this calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.