The Diffraction Grating

• When white light falls onto a diffraction grating, it produces a spectrum with all visible wavelengths separated according to their refractive indices.
• A diffraction grating is a plate with many closely separated slits.
• When a parallel beam of monochromatic light is directed at the grating along the normal, the beam will split into distinct lines.
• The central beam (along the normal) is the zero order beam. On either side, each subsequent beam is the first order, second order, and so on.
• Having the slits closer together will increase the angle of refraction between each refracted beam.
• Increasing the wavelength of the light will increase the angle of refraction between each refracted beam.
• d * sin(theta) = n * (wavelength)
• d = separation between individual grates
• theta = angle of diffraction of the beam
• n = order of the beam (zero, first, second...)
• maximum number of orders (n) = d / (wavelength), where n is rounded down to the next whole number.
• number of slits per meter (N) = 1/d