Armstrong, Nikaido, Marmelstein & Kubovcik
Photomagnetic differential reproducing system
 A linearly polarized light is projected upon a recording medium of a photomagnetic type; the reflected light is rotated by an appropriate angle through a halfwave plate and split into a reflected light and a transmitted light through a beam splitter having reflection factors of 0 or 100% for p- or s-polarized light in such a way that the beam splitter functions as an analyzer for one of the reflected and transmitted lights. The other of the reflected and transmitted lights is passed through an analyzer. The two lights passed through the beam splitter and the analyzer are detected by two photodetectors separately and applied to a differential amplifier to generate a reproduction signal of high S/N ratio without the use of a half mirror R.sub.p =R.sub.s =50% which is very difficult to manufacture. 
Olympus Optical Co., Ltd.
G
G11B
inventional
Nobuhide Kiichi
Matsubayashi Kato