Abstract: An optical recording medium includes a first transparent film layer, a second transparent film layer, and a recording material layer sandwiched between the first transparent film layer and the second transparent film layer. The recording material layer includes a hologram recording material.

Abstract: A reproducing device includes a homodyne detection part that carries out homodyne detection by using reflected light of first light obtained from a recording layer as signal light and using reflected light of second light by a mirror as reference light, a signal reproducing part that obtains a reproduced signal based on the signal light, based on a result of homodyne detection, and a one-axis actuator that drives the mirror. The reproducing device further includes an optical path length servo control part that carries out driving control of the one-axis actuator in such a manner that the optical path length difference between the signal light and the reference light is kept constant, and an offset giving part that gives an offset that reduces or enlarges the amplitude difference of the reproduced signal of marks that are recorded in the recording layer and have sizes different from each other.

Abstract: A recording medium includes a photosensitive layer, a nonphotosensitive layer, and a recording layer formation region in which the photosensitive layer and the nonphotosensitive layer are laminated. The photosensitive layer includes a recording layer in which interference fringes formed in parallel with a recording medium surface are deleted or changed within a portion irradiated with focused light to record information or light reflected during irradiation of focused light is used to reproduce information.

Abstract: A pickup apparatus includes a light source; a light separator; an object lens that concentrates the light which penetrated the light separator on the optical recording medium; a movable lens; and a light sensing element that receives the reflected light from the optical recording medium separated by the light separator, wherein a coma aberration generated by the transverse shift of the object lens is corrected by a coma aberration which is generated by the deviation of a spherical aberration generated in an optical path from the light source to the object lens and a spherical aberration generated in an optical path from the object lens to a light concentration position on the optical recording medium which are due to the transverse shift.

Abstract: A recording medium includes a photosensitive layer, a nonphotosensitive layer, and a recording layer formation region in which the photosensitive layer and the nonphotosensitive layer are laminated. The photosensitive layer includes a recording layer in which interference fringes formed in parallel with a recording medium surface are deleted or changed within a portion irradiated with focused light to record information or light reflected during irradiation of focused light is used to reproduce information.

Abstract: There is provided a method of initializing a recording medium having a first surface and a second surface which face to each other with a recording layer in between. The method includes forming interference patterns to have a pitch wider than ?r/2N by applying initializing light of a plane wave with a wavelength ?f to the recording layer from both of the first surface side and the second surface side, where ?r is a wavelength of reproducing light applied to the recording layer at the time of reproducing recorded information, and N is an average refractive index of the recording layer.

Abstract: A reproducing device includes a homodyne detection part that carries out homodyne detection by using reflected light of first light obtained from a recording layer as signal light and using reflected light of second light by a mirror as reference light, a signal reproducing part that obtains a reproduced signal based on the signal light, based on a result of homodyne detection, and a one-axis actuator that drives the mirror. The reproducing device further includes an optical path length servo control part that carries out driving control of the one-axis actuator in such a manner that the optical path length difference between the signal light and the reference light is kept constant, and an offset giving part that gives an offset that reduces or enlarges the amplitude difference of the reproduced signal of marks that are recorded in the recording layer and have sizes different from each other.

Abstract: A pickup apparatus includes a light source; a light separator; an object lens that concentrates the light which penetrated the light separator on the optical recording medium; a movable lens; and a light sensing element that receives the reflected light from the optical recording medium separated by the light separator, wherein a coma aberration generated by the transverse shift of the object lens is corrected by a coma aberration which is generated by the deviation of a spherical aberration generated in an optical path from the light source to the object lens and a spherical aberration generated in an optical path from the object lens to a light concentration position on the optical recording medium which are due to the transverse shift.