To provide a lighting device that can make the illuminance distribution in an effective lighting range more uniform by reducing the intensity of concentric circular interference fringes on a lit surface without influencing imaging performance even when a transmission type optical plane plate for illuminance distribution correction is introduced. 照度分布補正のための透過型光学平面板を導入した場合でも、被照明面における同心円状の干渉縞の強度を結像性能に影響の無いレベルに軽減させ、有効照明範囲内の照度分布をより均一にすることができる照明装置を提供する。 - 特許庁