A light quantity distribution control element includes a substrate of 20 mm\xd720 mm\xd73 mm made of a material that transmits light, such as optical glass or acryl, and a antireflective structure provided on a surface of the substrate. Each slider includes a heating element with a sufficient thermal expansion stroke to bring the area of the slider containing the transducer into contact with the disk surface to burnish the slider. A second path diverges between the condenser and the evaporator to supply a portion of the refrigerant discharged from the condenser to a path between the plurality of compressors.