Abstract: A nickel and/or cobalt chemical plating bath comprises: a salt of the metal(s) to be deposited; one or more complexing agents of said metal(s), a reducing agent based on boron or phosphorous; and a stabilizing agent. To avoid including sources of corrosion and/or toxic substances in the plating, the stabilizing agent comprises a water soluble organic compound which possesses a readily accessible electron pair, and which does not include any metal or metalloid from group IIIa (other than boron or aluminum), IVa (other than carbon), Va (other than nitrogen or phosphorous), VIa (other than oxygen), or VIIa (other than fluorine or chlorine).

Abstract: The device makes it possible to optically inscribe and/or read at least two facing sides of disks in an optical memory system, whose disks are stacked. A linear motor displaces a mobile means incorporating recording-reading heads. These heads receive via a bidirectional optical connection data to be inscribed and coming from fixed light emitters-receivers. Each of the recording heads comprises two focusing lenses associated with one of the two facing sides of the disk. According to a first variant, the two sides can be read simultaneously, each of the lenses being associated with its own control device. In a second variant, a single control device is provided and the two focusing lenses are integral with one another, each side being read or inscribed in succession.