Marc Amsler honor in ophthalmology. Amsler was professor and chief of the Zurich Eye Clinic until 1961. His successor was Rudolf Witmer. He is best known for the Amsler grid test. The Amsler grid was an improvement over the initial work done by the ophthalmologist Edmond Landolt. The grid tests the function of the macula, a part of the retina, so that macular degeneration can be identified. He also contributed to the progress in the understanding of uveitis. Furthermore, he published works on keratoconus. In 1951, Dr. Amsler performed the first corneal transplantation at the Zurich Eye clinic. Marc Amsler Marc Amsler
Control grid are strictly comparable, so there was no advance in this area. However, early screen-grid tetrodes of the 1920s, have C of only 1 or 2fF, around a thousand times less. 'Modern' pentodes have comparable values of C. Triodes were used in VHF amplifiers in 'grounded-grid' configuration, a circuit arrangement which prevents Miller feedback. Control grid The control grid is an electrode used in amplifying thermionic valves (vacuum tubes) such as the triode, tetrode and pentode, used to control the flow of electrons from the cathode to the anode (plate) electrode. The control grid usually consists of a cylindrical screen or