| 摘要 |
<p>A head (16) for detecting the position of a mark on a material under test comprises a lamp (33) that irradiates a circuit board (15a) with light, and a camera (31) that receives the reflection from the board (15a). A polarizer (35) is arranged in the optical path for incidence from the lamp (33) to the board (15a), and a polarizer (36) is arranged in the optical path for reflection from the board (15a) to the camera (31). The light reflected from a mark (M) can be clearly distinguished from that reflected from the other areas of the board (15a) even if the board (15a) has a high surface reflectivity.</p> |
