Karl Hermann Knoblauch (02.04.1820-30.06.1895) was a German physicist. He was born in Berlin. He was a Privatdozent at the University of Berlin, from 1849 professor at the University of Marburg and from 1853 at the university in Halle.
His research was mainly on the experimental study of thermal radiation. He studied the passage of heat rays through bodies, the emissive power of bodies and the properties of heat rays, and observed their double refraction, polarisation and diffraction (1846—48). He showed that the difference between heat rays and light rays lies in their wavelength. He proposed using the interference of infrared rays to determine their wavelength.
He was president of the Leopoldina Academy.