| 摘要 |
The present invention relates to an illumination optical system which uses infrared ray LEDs as a light source, and in which the optical system is coupled to the LED light source, and in which the angle of view to be infrared illuminated is adjustable in accordance with a zooming operation of the optical system. For this, an illumination system comprises: a plurality of lens groups sequentially arranged along an optical axis, from an LED light source side toward an illumination direction, wherein the lens groups comprises a first lens group (G1) having a positive refractive power; a second lens group (G2) having a positive refractive power; and a third lens group (G3) having a positive refractive power, wherein the second lens group (G2) moves to change the angle of irradiation for illumination. According to the present invention, an illumination optical system using infrared ray LEDs, which enables irradiation area to correspond to the size of the subject and to the variation of the distance to the subject, is provided with improved irradiation efficiency. |
