We report on an analyzer for elliptically polarized Lyman‐&agr; radiation (&lgr;=121.6 nm) which has a high transmission (14%) and can be used in ultrahigh vacuum. The analyzer consists of a pile of four MgF2plates and a MgF2quarter‐wave plate for Lyman‐&agr; light. We discuss examples for the application of this device by measurements of polarized Lyman‐&agr; light emitted after ion‐atom and ion‐surface collisions.