Diffracted Angle and Littrow Angle of Reflective Gratings

This calculator helps you compute the diffracted angle for a given incidence angle and the Littrow angle of reflective gratings.

If m is negative, the incident and diffracted beams lie on the same side of the grating normal. If m is positive, they lie on opposite sides of the normal.

$\frac{ \sin(\theta_m) + \sin(\theta_i) }{N} = m \lambda$

$\theta = \arcsin \left( \frac{N m \lambda}{2} \right)$

Groove (line) density $N$; Incidence angle $\theta_i$;
Diffraction order $m$; Wavelength $\lambda$;
Diffracted angle $\theta_m$; Littrow angle $\theta$;