Doc Kauffman (born Clayton Orr Kauffman, died June 26, 1990) was a lap steel guitar, electric guitar engineer, inventor & pinoeer of the worlds first patented guitar vibrola. The patent for "Apparatus for producing tremolo effects" was applied for in 1928 and officially granted to Doc Kauffman on January 5th, 1932. 
During the 1930s, Doc Kauffman served as chief electric guitars designer for Rickenbacker. Having invented and patented the first mechanical vibrato unit, Kauffman was able to implement his patented creation onto the Electro-Spanish Ken Roberts model as the instruments standard stock bridge. This addition would earn the rank as the first vibrola ever to be equipped, as a standard stock-option, on an electrified guitar. This would set precedence for the future development of electric guitars into the 1940s & 1950s. Notably, the Fender Stratocaster and Bigsby vibrato tailpieces. 
In the early 1940's, Doc Kauffman & Leo Fender would enter a business partnership, forming the K&F company in 1945. K&F only lasted 3 years, having produced amplifiers and lap steel guitars in small quantities. After Kauffman left, K&F transformed to Fender. Doc Kauffman & Leo Fender remained friends until Doc's death in 1990. Doc Kauffman considered Leo Fender such a close friend, Leo was listed as next to kin, after Doc's children, in Doc's final will & testament. Leo died just one year after Doc in 1991. 
Les Paul and Doc Kauffman struck a friendship in the 1930s. Les would later utilize the Kauffman Vibrola on his prototype "Log" guitars developed in the 1940s. Les favored the Kauffman vibrola to such a degree, he removed the stock bridge on his brand-new 1952 signature Gibson model and reinstalled the Kauffman vibrola.