The utility model provides an
infrared fast-
assembly lens, which comprises a fixed lens cone, one end of the fixed lens cone is fixedly provided with an installation sleeve, the inner wall of the installation sleeve is provided with a first thread matched with the connecting end of an
infrared equipment lens, and the other end of the fixed lens cone is provided with a movable lens cone; the movable lens cone comprises an outer lens cone and an inner lens cone detachably installed in the outer lens cone, the opposite ends of the inner lens cone and the outer lens cone are provided with a first limiting groove and a second limiting groove respectively, and a lens is placed between the two limiting grooves. According to the utility model, when dust or water mist on the lenses affects the use, the lenses can be independently detached and cleaned; the fixed lens cone and the movable lens cone can perform
relative displacement, so that the overall length of the device can be controlled, and zooming is realized.