PROBLEM TO BE SOLVED: To provide an excellent observation image regardless of near view observation, distant view observation, or the like.SOLUTION: An LPF (long pass filter) turret 32 and an SPF (short pass filter) turret 33 are installed in an optical path of broad band light BB. The LPF turret 32 is provided with a first LPF and a second LPF different in lower limit wavelength. The SPF turret 33 is provided with a first SPF and a second SPF different in upper limit wavelength. A distance discriminating part 57 is provided for discriminating a distance d between an insertion part distal end 16a and a site to be observed from special light image data obtained by imaging. An insertion pattern of the LPF/SPF inserted in the broad band light BB is determined to enlarge the half-value width of blue narrow band light generated after being transmitted through the LPF and SPF as the distance d is lengthened. The rotations of the LPF turret 32 and SPF turret 33 are controlled to insert the LPF/SPF according to an insertion pattern corresponding to the discriminated result of the distance discriminating part 57.COPYRIGHT: (C)2012,JPO&INPIT【課題】近景観察や遠景観察などに関係なく、良好な観察像を得る。【解決手段】広帯域光BBの光路に、LPFターレット32とSPFターレット33とを設ける。LPFターレット32に、下限波長が異なる第1LPFと第2LPFとを設ける。SPFターレット33に、上限波長が異なる第1SPFと第2SPFとを設ける。撮影により得られた特殊光画像データから、挿入部先端部16aと被観察部位との間の距離dを判別する距離判別部57を設ける。距離dが大きくなるのに従って、LPF及びSPFを透過して生成される青色狭帯域光の半値幅が拡がるように、広帯域光BBに挿入するLPF/SPFの挿入パターンを決定する。距離判別部57の判別結果に対応する挿入パターンに従って、LPF/SPFが挿入されるように、LPFターレット32及びSPFターレット33の回転を制御する。【選択図】図2
