The physicists Ernest Fox Nichols (1869-1924), a professor at Columbia University in New York, and Heinrich Rubens (1865-1922), a professor at the University of Berlin, designed a vane radiometer similar to that of Crookes, but simpler, more sensitive and precise, which is known as the Nichols radiometer.
In the Nichols radiometer the sensitive element consists of the blackened face of one of a couple of mica vanes mounted on a lightweight rod suspended from a quartz fibre on the inside of a recipient opaque to the radiations in which a vacuum has been created.
The radiation under observation strikes the blackened face through a thin mica plate, the mobile part of the instrument begins to turn and is stopped in a certain position by the antagonist moment of the fibre from which it is suspended.
The angle of rotation, which depends on the intensity of incident radiation, is measured optically by means of a mirror hanging on the suspending fibre.
Nichols and Rubens used radiometers of this kind in their studies on thermal radiation and in particular on that of the stars.