The diffraction grating analysis in this chapter assumed that the incident light is normal to the grating. Figure CP 22.73 shows a plane wave approaching a diffraction grating at angle Φ.

a. Show that the angles θ_m for constructive interference are given by the grating equation

where m = 0, ±1, ±2,. . . . Angles are considered positive if they are above the horizontal line, negative if below it.

b. The two first-order maxima, m = +1 and m = -1, are no longer symmetrical about the center. Find θ₁ and θ_-1 for 500 nm light incident on a 600 line/mm grating at Φ = 30°.

Transcribed Image Text:

Grating Incident wave Diffraction at angle o at angle 0