The utility model relates to the technical field of welcome lamps, and discloses a
focal length adjustable welcome lamp which comprises an upper cover, a lens A is in
lap joint with the top of the inner wall of the upper cover, a first
gasket is arranged at the bottom of the lens A, the outer edge of the first
gasket is fixedly connected with a lens
barrel in a sleeved mode, and the outer edge of the lens
barrel is in threaded connection with the inner wall of the upper cover. Through cooperative use of the upper cover and the lens
barrel, threaded connection between the upper cover and the lens barrel, and threaded connection between the lower cover and the lens barrel, the distance between the
condensing lens and the
imaging lens is adjusted by rotating the upper cover and assisting the lens barrel, so that the device is assisted in spiral focusing, and the imaging definition is adjusted to the optimal state. The lens B is made of plastic with the
refractive index higher than that of the lens A, the lens C and the lens D so as to assist the device in eliminating
chromatic aberration, the
imaging lens is composed of a concave lens and a convex lens so as to assist the device in stably eliminating
chromatic aberration, the lens F is of a concave-
convex structure, and the lens E is of a biconvex lens so as to improve the illumination uniformity of the device.