| 摘要 |
PURPOSE:To prevent a diffracted light from being erroneously recognized as a scattering light from dust particle when a photodetecting system detects the diffracted light from a repeated pattern. CONSTITUTION:A detecting system 3 has a light source 1 for projecting an inspection light to a to-be-inspected body and a photodetecting system 2 for detecting a scattering light from the to-be-inspected body. The detecting system outputs a position signal indicating the position where the scattering light is generated and a light intensity signal representing the intensity of the scattering light. A signal processing system 4 detects a place where dust particles are given rise to on the basis of the position signal and the light intensity signal from the detecting system 3 and, generates a dust particle signal indicating the detecting place. A data processing system 11 judges when receiving the dust particle signal from the signal processing system 4 whether the place of the dust particle is continuous or periodic on the basis of the light intensity signal and the dust particle signal. The data processing system 11 removes a dust particle signal of the continuous or periodic characteristic from the receiving signals and outputs the remaining dust particle signal, i.e., a correcting dust particle signal to a display device 6. |
