In 1922, a patent was filed for the first projection lensmeter, which has a similar system to the standard lensmeter pictured above, but projects the measuring target onto a screen eliminating the need for correction of the observer's refractive error in the instrument itself and reducing the requirement to peer down a small telescope into the  instrument.
In 1922, a patent was filed for the first projection lensmeter. This device has a comparable system to standard lensmeters, projecting the measuring target onto a screen to avoid correcting the observer's refractive error within the instrument and decreasing the need to look into a small telescope inside it.