| 摘要 |
PURPOSE:To control the quantity of incident light from a highlight part to an optimum level without decreasing the quantity of incident light except from the highlight part greatly, and prevent blooming and halation by providing a polarizing plate or quarter-wavelength plate rotatably within a proper angle range. CONSTITUTION:The polarizing plate 13 is held pivotally at iris positions on both optical paths in front of an objective lens 3 and a light distribution lens 6 provided adjacently and successively at the tip part of an endoscope, and the quarter-wavelength plate 14 is arranged further before the polarizing plate 1; and the polarizing plate 13 has its angle theta of rotation controlled by a rotation driving means 15 which is driven with a control signal. When the axis beta of polarization of the polarizing plate 13 is rotated almost to 45 deg. to the crystal axis beta of the quarter-wavelength plate 14, illumination light is made by the polarizing plate 13 into linear polarized light in the direction of the axis beta of polarization and the phase of the component in the direction of the crystal axis beta is shifted by 45 deg. through the quarter-wavelength plate 14 to obtain nearly circular polarized wave gamma, which illuminates a subject. |
