| 摘要 |
<p>????An image pickup lens has a focal length far from a position of a transparent member. An image pickup device is put on the side of the transparent member the same as that of a light source and takes reflected light including regular reflection from an interface between an adhered object on the other surface of the transparent member and air. Assuming an incident angle of the emitted light on the transparent member when the light reflected in regular reflection by the other surface of the transparent member is incident on the image pickup lens being s an incident angle of a typical light beam of the emitted light falls within s 30 deg through s and an incident angle of a main element of the emitted light is less than s.</p> |
