Physician, with a special interest in the study of anatomical structures. In 1740, he gave the Royal Society of London a demonstration of one of his inventions, which proved effective for the lighting of small opaque objects. The device became known as a "lieberkuhn mirror." It consisted of a concave reflector circling the microscope objective: the light surrounded the specimen to be examined and was reflected back onto the object by the spherical mirror fitted around the lens.