Oblon, Spivak, McClelland, Maier & Neustadt
Optical information recording medium and recording method
 An optical information recording medium comprising a light transmitting substrate having a spiral pregroove formed on its surface, a light absorptive layer of a coloring matter formed on the substrate directly or with other layer interposed therebetween, and a light reflective layer made of a metal film formed on the light absorptive layer directly or with other layer interposed therebetween, wherein .DELTA.S.ltoreq.0.3 wherein .DELTA.S is the optical phase difference represented by .DELTA.S=2d.sub.sub {n.sub.sub -n.sub.abs (1-d.sub.abs /d.sub.sub)}/.lambda. wherein d.sub.sub is the depth of the layer boundary on the substrate side of the light absorptive layer at the portion corresponding to the pregroove, d.sub.abs is the depth of the layer boundary on the light absorptive layer side of the light reflective layer at the portion corresponding to the pregroove, n.sub.sub is the real part of the complex refractive index of the substrate and any layer present on the substrate side of the light absorptive layer, n.sub.abs is the real part of the complex refractive index of the light absorptive layer, and .lambda. is the wavelength of a laser beam. 
Taiyo Yuden Co., Ltd.
Y Y G Y Y
Y10T Y10S G11B Y10T Y10S
additional additional inventional additional additional
Toru Kunihiko Emiko Yosikazu
Fujii Ootaguro Hamada Takagisi