HIGH DENSITY OPTICAL REPRODUCING DEVICE

摘要

PURPOSE:To reproduce magnetization information smaller than the diameter of a spot by irradiating a recording medium with two kinds of laser light beams having a different wavelengths, superposing the parts of both spots on each other and setting the difference of the detection signals of reflected light from both spots as a reproducing signal. CONSTITUTION:The laser light beams which are emitted from semiconductor lasers 1 and 1' and have the wavelengths lambda1 and lambda2 respectively are made incident on a beam splitter BS5 directly or through a polarizing plate 3 to be synthesized. The synthesized light beam is made incident on a recording film 10 through a BS5' and a lens 6 to generate two spots whose parts are superposed. After the reflected light is reflected on the BS5' and separated in accordance with the wavelength by a wavelength separating filter 7, it is made incident on photodetectors 9 and 9' through polarizing plates 8 and 8'. Output from the photodetectors 9 and 9' is inputted in a differential amplifier and the difference signal is outputted as the reproducing signal.