Before revision: Around 1916 Michael Woolf, also of New York City, bought him out and added his own invention,US Patent 1,240,289 Applied 1916 Patented 1917 an innovative battery of cylinder lenses, ranging from -0.25 to -2.00, to the device, as well as Risley prisms for each eye.
After revision: Around 1916 Michael Woolf, also of New York City, bought him out and added his own invention,US Patent 1,240,289 Applied 1916 Patented 1917 an innovative battery of cylinder lenses, ranging from 0.25 to 2.00 D to the device, as well as Risley prisms for each eye.