A method of making a fused silica plate includes providing a fused silica blank having a length, a longitudinal axis, and an outer diameter. The method further includes forming a slot in the fused silica blank which extends from the outer diameter to a location at or offset from a center of the fused silica blank and is substantially parallel to the longitudinal axis of the fused silica blank. The slot is defined by a concave surface located at or offset from the center of the fused silica blank, a first side surface extending between a first edge of the concave surface and the outer diameter of the fused silica blank, and a second side surface extending between a second edge of the concave surface and the outer diameter of the fused silica blank. At least one of the first and second side surfaces are connected to the concave surface by a chamfered surface. The method further includes rolling out the fused silica blank having the slot to form a fused silica plate.