Intermediate infrared band relay lens

The utility model discloses a middle infrared band relay lens comprising a first lens and a second lens which are arranged along an optical axis in sequence, the first lens is a plano-convex lens, the second lens is a biconcave lens, the first lens is a positive focal lens, the plane of the first lens faces a Chart plate, and the convex surface of the first lens faces a detected module; the first lens is a negative focus lens, the first surface 3 of the first lens faces the Chart plate, the second surface 4 of the first lens faces the tested module, the curvature radius value of the first surface 3 is smaller than that of the second surface 4, and the first lens and the second lens are spherical lenses made of germanium glass materials. The wavelength range of the middle infrared band is 8-12 [mu] m; the relay lens has the following advantages: the exit pupil value is large; the exit pupil diameter value is 6.4; a structure of two pieces of glass is adopted, but good imaging quality is achieved; lenses used i