Dayoptics Pockel Cell LiNbO₃ consists of two matched lithium niobate crysrals packaged in a compact housing. Applying an electric field to the crystal induces a change of refraction, giving rise to an electric field-dependent birefringence, which leads to a change in the polarization state of the optical beam. The EO crystal acts as a variable waveplate with retardance linearly in the applied electric field. By placing a linear polarizer at the exit, the beam intensity through the polarizer varies sinusoidal with linear change in applied voltage.