フリードリヒ・ヴィルヘルム・ベッセル
The filter's name is a reference to German mathematician Friedrich Bessel (1784–1846), who developed the mathematical theory on which the filter is based. The filters are also called Bessel–Thomson filters in recognition of W. E. Thomson, who worked out how to apply Bessel functions to filter design in 1949. (In fact, a paper by Kiyasu of Japan predates this by several years.)