Abstract: A novel method for forming a positive electrode active material is provided. The method for forming a positive electrode active material includes causing a reaction between a cobalt aqueous solution and an alkaline aqueous solution to form a cobalt compound; mixing the cobalt compound and a lithium compound and performing a first heat treatment to form a first composite oxide; mixing the first composite oxide and a compound containing a first additive element and performing a second heat treatment to form a second composite oxide; and mixing the second composite oxide and a compound containing a second additive element and performing a third heat treatment. The first heat treatment is performed at a temperature higher than or equal to 700° C. and lower than or equal to 1100° C. The second heat treatment is performed at a temperature higher than or equal to 700° C. and lower than or equal to 1000° C.

Abstract: A hologram recording device for producing a hologram that diffracts incident light includes: a laser light source; a first half-wave plate that controls a polarization direction of a light beam emitted from the laser light source; a polarizing beam splitter that reflects S-polarized light to emit the S-polarized light as an “A” light ray and transmits P-polarized light to emit the P-polarized light as a “B” light ray with respect to the light beam passing through the first half-wave plate, and splits the light beam in two directions; a first wedge prism mirror that reflects the “A” light ray; a second half-wave plate that polarizes the “B” light ray into S-polarized light; a second wedge prism mirror that reflects the S-polarized light polarized by the second half-wave plate; and a recording medium irradiated with light rays reflected by the first wedge prism mirror and the second wedge prism mirror.

Abstract: When an optical disc apparatus of the present invention writes to an optical disc, it detects the level of the drive voltage for its laser drive circuit and, based on the detected level, adjusts the drive voltage for its laser diode so as to adjust the drive voltage for the laser drive circuit to a level within an appropriate range. Further, the write speed is also adjusted in accordance with the above adjustment of the drive voltages for the laser drive circuit and the laser diode.

Abstract: An optical disc apparatus in which processing time is shortened and processing accuracy is ensured upon focus offset processing for plural recording layers. Regarding each of mutually adjacent recording layers, based on a signal based on reflected light from a guide groove formed in a recording surface of the recording layer, a focus offset for an optical system with respect to the guide groove is learned, and based on the learned focus offsets for the respective recording layers, a focus offset for recording or reproduction is calculated and set. In an optical disc having three or more recording layers, a focus offset when the difference between the focus offset and the learned focus offsets for the respective recording layers is a value corresponding to the characteristic of the optical system is set as a focus offset for the respective recording layers or a common focus offset to the respective recording layers.

Abstract: An optical disc apparatus in which, regarding mutually adjacent recording layers, a focus offset of an optical system to a guide groove formed in a recording surface of the recording layer is learned based on a signal based on reflected light from the guide groove, and a focus offset for recording or reproduction is calculated and set based on the learned focus offsets for the respective recording layers. As the focus offset of the optical system for recording or reproduction, a mean value of the learned focus offsets for the respective recording layers is set as a focus offset common to the both recording layers. Otherwise, a focus offset when a difference between the focus offset and the learned focus offsets for the respective recording layers is a value corresponding to a characteristic of the optical system is set. This structure reduces processing time and ensures processing precision upon focus offset processing for plural recording layers.

Abstract: When an optical disc apparatus of the present invention writes to an optical disc, it detects the level of the drive voltage for its laser drive circuit and, based on the detected level, adjusts the drive voltage for its laser diode so as to adjust the drive voltage for the laser drive circuit to a level within an appropriate range. Further, the write speed is also adjusted in accordance with the above adjustment of the drive voltages for the laser drive circuit and the laser diode.