Apparatus and method for detecting the surface defect of the glass substrate

The invention relates to an apparatus for detecting surface defects of a glass substrate, having a dark field optical system disposed below the glass substrate and emitting light upwards such that the emitted light is incident on an imaginary line approximately vertical to a transfer direction on a lower surface of the glass substrate, refracted in a thickness direction of the glass substrate, and then passes through the imaginary line approximately vertical to the transfer direction on an upper surface of the glass substrate; a first photographing device photographing an area of the imaginary line formed on the upper surface of the glass substrate; a second photographing device photographing an area of the imaginary line formed on the lower surface of the glass substrate; and a detection signal processor determining which surface foreign matter is attached to among the upper and lower surfaces of the glass substrate by comparing images input from the first and second photographing devices shines upward.