Novel long-wave infrared prime lens

The utility model provides a novel long-wave infrared prime lens. The novel long-wave infrared prime lens is characterized in that three lenses are sequentially arranged along the optical axis from an object space to an image space, the first lens is a meniscus lens with positive refractive power, a convex surface of the meniscus lens faces the object space, the second lens is a lens with negative refractive power, the third lens is a lens with positive refractive power, a convex surface of the third lens faces the image space, the novel long-wave infrared prime lens meets formulas that FNOXf12Xf3X(n1-1)/(fXfXR1) is larger than 0 and smaller than 1 and dn1/dT is larger than 1X10 and smaller than 5X10, the f is the focal length of an integral optical system, the n1 is a central wavelength refractive index of materials of the first lens, the FNO is an F number of the optical system, the f12 is a combined focal length of the first lens and the second lens, the f3 is the focal length of the third lens, th