An optical apparatus according to an embodiment of the present disclosure is an apparatus that performs one or both of writing and erasing of information with respect to a reversible recording medium. This optical apparatus includes a plurality of laser devices varying in emission wavelength in a near infrared region (700 nm to 2500 nm), an optical system that multiplexes laser beams outputted from the plurality of laser devices, and a scanner unit that scans a multiplexed light beam obtained by multiplexing by the optical system, on the reversible recording medium.

A reversible recording medium according to an embodiment of the present disclosure is a reversible recording medium that includes recording layers and heat-insulating layers that are alternately stacked, in which the recording layers each include a reversible heat-sensitive color developing composition and a first light-heat converting agent. In this reversible recording medium, the recording layers are different from each other in a developing color of their respective reversible heat-sensitive color developing compositions and are different from each other in an absorption wavelength of their respective first light-heat converting agents. This reversible recording medium further includes a heat-generating layer that includes a second light-heat converting agent having an absorption wavelength that is different from the absorption wavelength of the first light-heat converting agent included in each of the recording layers.

A recording medium according to one embodiment of the present disclosure includes a recording layer and an optical thin film. The recording layer includes a heat-sensitive color-developing composition and a photothermal conversion material. The photothermal conversion material absorbs a wavelength in an infrared region and generates heat. The optical thin film is provided on one surface of the recording layer. The optical thin film reflects the wavelength in the infrared region and transmits a wavelength in a visible region.

A reversible recording medium according to an embodiment of the present disclosure includes a first recording layer to be colored in a first color, a second recording layer to be colored in a second color, the second color being different from the first color, and a first intermediate layer provided between the first recording layer and the second recording layer, the first intermediate layer including a plurality of layers respectively containing materials different from each other.

An optical apparatus according to an embodiment of the present disclosure is an apparatus that performs one or both of writing and erasing of information with respect to a reversible recording medium. This optical apparatus includes a plurality of laser devices varying in emission wavelength in a near infrared region (700 nm to 2500 nm), an optical system that multiplexes laser beams outputted from the plurality of laser devices, and a scanner unit that scans a multiplexed light beam obtained by multiplexing by the optical system, on the reversible recording medium.

A reversible recording medium according to an embodiment of the present disclosure is a reversible recording medium that includes recording layers and heat-insulating layers that are alternately stacked, in which the recording layers each include a reversible heat-sensitive color developing composition and a first light-heat converting agent. In this reversible recording medium, the recording layers are different from each other in a developing color of their respective reversible heat-sensitive color developing compositions and are different from each other in an absorption wavelength of their respective first light-heat converting agents. This reversible recording medium further includes a heat-generating layer that includes a second light-heat converting agent having an absorption wavelength that is different from the absorption wavelength of the first light-heat converting agent included in each of the recording layers.

A thermosensitive recording medium according to an embodiment of the present disclosure includes: a recording layer that includes a coloring compound having electron-donating property, a developer having electron-accepting property, a photothermal conversion agent, and a polymer material; and a protective member that is stacked on the recording layer, and has a convexo-concave shape in a plane.

An erasing unit according to an embodiment of the present disclosure is a unit that performs erasing of information written on a reversible recording medium. This erasing unit includes: a light source section including one or a plurality of laser devices; and a controller that controls the light source section to cause the light source section to emit a smaller number of laser light beams having emission wavelengths than the number of the recording layers included in the reversible recording medium.

An optical apparatus according to an embodiment of the present disclosure is an apparatus that performs one or both of writing and erasing of information with respect to a reversible recording medium. This optical apparatus includes a plurality of laser devices varying in emission wavelength in a near infrared region (700 nm to 2500 nm), an optical system that multiplexes laser beams outputted from the plurality of laser devices, and a scanner unit that scans a multiplexed light beam obtained by multiplexing by the optical system, on the reversible recording medium.

A reversible recording medium according to an embodiment of the present disclosure is a reversible recording medium that includes recording layers and heat-insulating layers that are alternately stacked, in which the recording layers each include a reversible heat-sensitive color developing composition and a first light-heat converting agent. In this reversible recording medium, the recording layers are different from each other in a developing color of their respective reversible heat-sensitive color developing compositions and are different from each other in an absorption wavelength of their respective first light-heat converting agents. This reversible recording medium further includes a heat-generating layer that includes a second light-heat converting agent having an absorption wavelength that is different from the absorption wavelength of the first light-heat converting agent included in each of the recording layers.