ALEXANDRIA, Va., Feb. 24 -- United States Patent no. 12,560,783, issued on Feb. 24.
"Fixed focal length objective" was invented by Stefan Roth (Lahnau, Germany).
According to the abstract* released by the U.S. Patent & Trademark Office: "The invention relates to a fixed focal length objective having a stationary lens group forward in the direction of light (VG), a stationary diaphragm (BL) with an adjustable aperture, a stationary rear lens group (HG) and a focussing group (MG) displaceable relative to the diaphragm along the optical axis of the objective for imaging objects at different distances onto a stationary image plane (IM), in which lens the focussing group (MG) consists of at least one lens element and a diffractive optical elem...