Light with wavelength λ=589.0nm\lambda=589.0 \mathrm{nm}λ=589.0nm falls normally on a diffraction grating with period d=2.5μm,d=2.5 \mu \mathrm{m},d=2.5μm, comprising N=N=N= =10000=10000=10000 lines. Find the angular width of the diffraction maximum of second order.