How do I find the diffraction angle?

Use. If the ratio is greater than 1, that order does not exist.

What does 600 lines/mm mean?

It means 600 grooves per millimeter. The spacing is about 1,666.7 nm.

What is maximum diffraction order?

The maximum order is the largest integer m for which m is not greater than 1.

Diffraction Grating Calculator

Calculate diffraction angle, wavelength, grating spacing, line density, maximum order, angular dispersion and resolving power from the grating equation.

Diffraction grating

Choose whether to solve for angle, wavelength, grating spacing, or existing orders.

Solve for

Grating spacing

Input method

Line density, lines/mm

Spacing, nm

For example, a 600 lines/mm grating has spacing of about 1666.67 nm.

Light wavelength

Source

Wavelength, nm

Diffraction order

Resolving power

Illuminated width, mm

Total illuminated lines

If illuminated width is entered, illuminated lines come from width and line density. If width is empty, enter the total line count manually.

Grating equation

English SERP intent is a lab optics calculator for the relationship between grating spacing, wavelength, order and diffraction angle.

d sin θ = mλ

d is grating spacing, theta diffraction angle, m order and lambda wavelength.

N_{lines/mm} = \frac{1 0 ^{6}}{d _{nm}}

Line density and grating spacing are two ways to describe the same grating.

R = m N

Resolving power depends on order and the number of illuminated grooves.

Model limits

Laser safety

Do not aim lasers into eyes or reflective paths. The calculator estimates angles and resolving power; it does not model beam power or lab safety controls.

Frequently Asked Questions

Sources and References

Calculations are based on the listed reference sources. Links open in a new tab.

Updated: June 2, 2026

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