Optical recording medium and method for producing same

A method for producing an optical recording medium, the method comprising the steps of:

• forming crests and valleys to form pits corresponding to information signals on a master disc by light exposure and corresponding development;
• forming a transparent substrate having crests and valleys by transcription from the master disc;
• forming a reflective film on a surface of the transparent substrate having said crests and valleys formed thereon;
• and
• bonding together first and second signal recording layers each of which is comprised of said transparent substrates having the reflective films formed thereon so that said signal recording layers are facing each other with an adhesive therebetween;
• wherein,
• a length and a width W2 of a valley of said second signal recording layer from which information is reproduced by reverse direction reproduction by a light beam illuminated from the side of its reflective film are larger by a reflective film thickness than a length and a width W1 of a valley of said first signal recording layer from which information is reproduced by forward reproduction by a light beam illuminated from its transparent substrate, and
• said crests and valleys of said recording layers being formedso that an asymmetry A1 of reproduced signals obtained from said first signal recording layer by forward direction reproduction by irradiation from the side of its transparent substrate will be effectively equal to an asymmetry A2 of reproduced signals obtained from the second signal recording layer by reverse direction reproduction by being irradiated with a light beam through the transparent substrate of the first signal recording layer, asymmetry of reproduced signals being determined by the following relationship:
• ((ILtop+ILpit)−(IHtop+IHpit))/2(ILpit−ILtop)
• where ILpit, ILtop denote return light levels of the longest valley and land, respectively, while IHpit and IHtop denote return light levels of the shortest valley and land, respectively.