Patent ID: 7440103

Claim:
A wiring pattern detection apparatus which optically detects an uppermost-layer wiring pattern of a work comprising a multilayered wiring substrate for a semiconductor package having wiring patterns on at least front/back surfaces of a light-transmitting base film, the apparatus comprising: a light source; parallel light guiding means for guiding light from the light source substantially in parallel; first extraction means for extracting first linearly polarized light whose electric-field vector direction crosses a guiding direction of the light at right angles from the light guided by the parallel light guiding means; circularly polarized light conversion means for converting the first linearly polarized light extracted by the first extraction means into circularly polarized light; irradiation means for irradiating the work with the circularly polarized light converted by the circularly polarized light conversion means; second extraction means for extracting second linearly polarized light whose electric-field vector direction crosses the first linearly polarized light at right angles from reflected light obtained by reflecting the circularly polarized light emitted by the irradiation means by the work; and image pickup means for imaging the second linearly polarized light extracted by the second extraction means, wherein the parallel light guiding means comprises a light guide to guide the light from the light source; a diffusion plate to diffuse the light from the light source while keeping an intensity distribution to be constant; paralleling means for bringing the light diffused by the diffusion plate substantially in parallel; and means for guiding the parallel light brought by the paralleling means.