Patent ID: 8264940

Claim:
An apparatus comprising: a light source for emitting a laser beam; a lens for condensing the laser beam onto an information recording medium; and a photodetector for detecting light that has been reflected from the information recording medium, wherein a recording layer of the information recording medium includes a material that absorbs the laser beam at an increasing absorptance as the absorption edge of a light absorption spectrum shifts, with a rise in temperature, toward a longer wavelength range as a result of a band-to-band transition of electrons, and wherein the apparatus further includes: a wavelength detecting section for detecting at least one of the wavelength of the laser beam and a variation in the wavelength; a temperature sensing section for sensing at least one of the temperature of the information recording medium itself or its ambience and a variation in the temperature; and a control section for controlling the power of the light source based on the respective outputs of the wavelength detecting section and the temperature sensing section, and wherein in performing a recording operation, if the variation in the wavelength of the laser beam from its value in a reference state is identified by Δλ and if the variation in the temperature of the information recording medium itself or its ambience from its value in the reference state is identified by ΔT, the control section controls the power of the light source so that Δλ/ΔT falls within a predetermined range, wherein in performing a recording operation, if the variation in the wavelength of the laser beam from its value in a reference state is identified by Δλ, the variation in the temperature of the information recording medium itself or its ambience from its value in the reference state is identified by ΔT, their factors of proportionality are identified by k 1 and k 2 , respectively, and the power of the light source in the reference state is identified by P 0 , the control section controls the power P of the light source so that the power P satisfies 0.9P 0 (k 1 Δλ)/(k 2 ΔT)≦P≦1.1P 0 (k 1 Δλ)/(k 2 ΔT).