A boundary with a small opening. There is a vector straight from the opening labeled D and an angle labeled theta to another ray, both striking a surface with a red point. The distance between the two red points is labeled y. A laser diffraction pattern results in y = 6.0 cm, and the distance from the gap to the screen is D = 12 cm. The tangent of θ would be equal to . Calculating the inverse (tan–1) of the value for the tangent of θ would give us a diffraction angle, θ, of degrees.