With the subject image by the reflection of illumination light of the visible light range and the fluorescent image by the fluorophor in subject the aperture diaphragm 100A for illumination which is used for the light equipment when simultaneously you observe, the filter field 1 which was formed to plate-like backing material 3, has the aperture field 2 which was formed inside the filter field 1. The filter field 1 makes the light of the wavelength area of the excited light transmit which radiates fluorescence to subject, decreases or cuts off the transmission of light of the visible light range which at the same time forms the subject image. As for aperture diaphragm 200A for illumination, part or the multiple having, the filter field 1 is formed the diaphragm feather component 20A where filter section 21 was formed entirely from that multiple diaphragm feather components, 20A is possible that the aperture field 2 is formed inside the filter field 1. Because of this, it can improve the ratio of the light intensity of the subject image by the reflection of illumination light and the feeble fluorescent image by the fluorophor in subject.可視光域の照明光の反射による被写体像と、被写体中の蛍光物質による蛍光像とを同時に観察する場合の光源装置に使用される照明用開口絞り100Aが、平板状基材3に形成されたフィルタ領域1、フィルタ領域1の内側に形成された開口領域2を有する。フィルタ領域1は、被写体に蛍光を発光させる励起光の波長域の光を透過させ、かつ被写体像を形成する可視光域の光の透過を低減又は遮断する。照明用開口絞り200Aは、一部又は全部にフィルタ部21が形成された絞り羽根部材20Aを複数備え、その複数の絞り羽根部材20Aからフィルタ領域1が形成され、フィルタ領域1の内側に開口領域2が形成されるようにしてもよい。これにより、照明光の反射による被写体像と被写体中の蛍光物質による微弱な蛍光像との光量の比率を改善することができる。
