APPARATUS FOR MEASURING PARTICLE SIZE DISTRIBUTION BY LIGHT SCATTERING

摘要

Apparatus for determining particle-size distribution of a sample by light-scattering includes a helium neon laser (102), a sample cell having cell windows (120, 122) and a focal plane detector (124). Detectors are also provided for detecting light scattered by a sample within or flowing through the sample cell. The apparatus includes a first (114) and second (116) folding mirrors arranged to fold the optical path from the laser to the sample cell so that the laser is vertically below the sample cell. The folding mirrors are mounted within a dust-proof housing (104), the entrance (106) and exit (108) components thereof being other optical components generally used within light- scattering apparatus. The entrance component is mounted such that its outward normal points downwards and the exit component is mounted substantially vertically so that these components do not accumulate dust. The invention allows the laser of a light-scattering apparatus to be positioned vertically below a sample cell of the apparatus without the accumulation of dust on optical components, which tends to degrade performance.

主权项

1. Apparatus for measuring the particle-size distribution of a sample by light scattering, the apparatus comprising a light source arranged to provide an output beam along an optical path to a sample cell, or means for holding a sample cell, the optical path being folded at a first folding mirror having mirror normal in a direction which has a component in an upward direction when the apparatus is its normal operating orientation, and wherein the first folding mirror is contained within a dust-proof housing having an optical entrance and exit optical components the outward normals of which are either substantially horizontal or have a component in a downward direction when the apparatus is in its normal operating orientation.