Backlight device and liquid crystal display apparatus

A planar light source device comprising:

• a first light source for emitting a first light ray which has a punctate spatial luminance distribution when the first light ray is emitted;
• a second light source for emitting a second light ray;
• a first spatial luminance distribution conversion portion for receiving the first light ray, changing the first light ray from the punctate spatial luminance distribution to a linear spatial luminance distribution, and then exiting the first light ray;
• a second spatial luminance distribution conversion portion for receiving the first light ray having the linear spatial luminance distribution and the second light ray, changing a spatial luminance distribution of the received first light ray and a spatial luminance distribution of the received second light ray to a planar spatial luminance distribution, and then exiting the first light ray and the second light ray as planar light;
• and
• an optical element disposed on an optical path from a light emitting surface of the first light source to a light incidence face of the second light source where the first light ray enters, the optical element spreading a divergence angle of the first light ray in the slow-axis direction on the optical path;
• wherein:
• the first light ray is a laser light;
• the second light ray has a divergence angle larger than the divergence angle of the first light ray when the first light ray is emitted from the first light source;
• and
• a slow-axis direction of the first light ray entering the second spatial luminance distribution conversion portion is parallel to an outgoing direction of the planar light.