| 摘要 |
<p>PURPOSE:To detect pinholes while discriminating them from dust, by irradiating the same part on the sample surface from vertical and oblique directions, receiving the rays reflected in the vertical direction and comparing both rays with each other. CONSTITUTION:By an irradiating light source 7, a sample 1 is vertically irradiated through a condenser lens 8, a half-mirror 9 and an objective lens 10. Moreover, the sample 1 is obliquely irradiated by irradiating light sources 12 and 13 through condenser lenses 14 and 15. Shutters 19-21 have been inserted in the respective optical paths. First, with only the shutter 19 opened, a vertical irradiation is performed to detect dust and pinholse by means of an image pickup apparatus 11. Then, with only the shutters 20 and 21 opened, oblique irradiations are performed to detect only dust. This is because in the oblique irradiations, the light scattered by pinholes is approximately specularly reflected and consequently not converged by the objective lens 10, but the light applied to dust is scattered thereby in all directions because of the irregularity in shape and converged by the objective lens 10. Comparing both ligt with each other permits pinholes to be detected. In addition, if light of different wavelengths is employed for the vertical and oblique irradiations respectively, inspection can be performed by means of simultaneous irradiations.</p> |
