an acousto - optic deflector that utilizes second order diffraction in a birefringent crystal provides doubled resolution while maintaining high diffraction efficiency . for the second order birefringent deflector employing a paratellurite crystal , 1200 spot resolution was achieved with a 24 mhz bandwidth and 25 μ sec access time . this maximum number of spots is twice that obtainable in a conventional first order acousto - optic deflector .