Our harmonic beamsplitters are designed to separate Nd:YAG laser harmonics after frequency multiplication. These 25.4 mm diameter optics are precision polished select grade fused silica coated with hard refractory multilayers for high damage threshold. A damage resistant antireflection coating for the transmitted harmonic is applied to the back surface to further improve transmission. Each coating design has been tested to guarantee reliable operation with high fluence Nd:YAG lasers.