This is a dictionary of field names to use dor describing a X-ray lens as used at synchrotron beam lines. Based on information provided by Gerd Wellenreuther. Geometry of the lens Is the device symmetric? Is the device cylindrical? Orientation of the cylinder axis. The type of focus of the lens Thickness of the lens Length of the lens Radius of the curvature as measured in the middle of the lens Diameter or radius of the lens. Number of lenses that make up the compound lens. Material used to make the lens. Gas used to fill the lens Gas pressure in the lens