Patent ID: 6999170
Filing Date: 2006-02-14
Classification: G01N

Abstract:
1. An optical analysis apparatus for determining the number of particles serving as measured objects within a certain size range, from particles of various sizes in a specific area of an analysis optical disc, the analysis apparatus, comprising: a disc rotating device for rotating the analysis optical disc, a light-emitting device for emitting a light beam to the analysis optical disc, a scanner for driving the light-emitting device to scan the light beam having been emitted to the analysis optical disc, a light detector which is disposed on an opposite side of the analysis optical disc from the light-emitting device and has at least two receiving parts for receiving passing light of the light beam emitted from the light-emitting device to the analysis optical disc, the light-receiving parts having therebetween a boundary substantially orthogonal to a direction of scanning the light beam, a differential signal detection circuit constituted of a differential signal detection part which extracts a differential signal obtained by differentiating a signal of the passing light from the light-receiving parts of the light detector when the light beam passes through a particle, a differential signal memory, a differential signal decision part which decides whether a particle is present in the specific area of the analysis optical disc by using a first threshold value as a criterion for deciding presence of a particle based on the differential signal extracted by the differential signal detection part, and stores a result in the differential signal memory, and a particle presence decision part which scans the differential signal memory by using a first scanning window corresponding to a particle serving as a measured object within a certain size range, and decides the presence or absence of a particle serving as a measured object within the certain size range, a sum signal detection circuit constituted of a sum signal detection part which extracts a sum signal of the passing light from the light-receiving parts of the light detector when the light beam passes through a particle, a sum signal memory, a sum signal decision part which decides whether the analysis optical disc has a countable particle by using a second threshold value as a criterion for deciding whether a particle is countable based on the sum signal extracted by the sum signal detection part, and stores a result in the sum signal memory, and a particle effectiveness decision part which scans the sum signal memory by using a second scanning window for deciding effectiveness of counting a particle, and decides the effectiveness of counting a particle, and a particle detection circuit which determines the number of particles having a minimum size when the particle presence decision part and the particle effectiveness decision part decide that a particle having the minimum size is present among the particles serving as measured objects within the certain size range and counting of the particle is effective, and determines the number of detected particles having a size one scan larger than a maximum value and determines the number of detected particles within the certain size range based on a difference between the number of detected particles having the minimum size and the number of detected particles having a size larger than the maximum value by one scan, when the particle presence decision part and the particle effectiveness decision part decide that a particle having a size larger than the maximum value by one scan is present among the particles within the certain size range and the counting of the particle is effective.