Detector apparatus for laser light scattering photometers

Abstract

Detector apparatus for a laser light scattering photometer of the type for measuring radiant power scattered from a sample at a selectable angle with respect to the direction of an incident beam of radiant power and for measuring radiant power transmitted through the sample in the direction of the incident beam. The improved detector apparatus receives and detects the scattered power and the transmitted power and provides an output indicative of the radiant power of each independent of the spatial properties of the two beams. The detector apparatus comprises a planar diffuser spaced from and parallel to the large area end-window of a photomultiplier detector, the diffuser diffusing the energy over the surface of the end-window. The diffuser and photomultiplier detector are positioned within a cylindrical container which is enclosed at the end thereof in front of the diffuser, the enclosed end of the container having an aperture therein through which the beams pass to the diffuser. By making the inside surface of the cylindrical container, and the end thereof, highly reflective, the energy which is reflected from the end-window of the detector is reflected back thereto preventing a loss of sensitivity. A high pass filter-spacer may be positioned between the diffuser and the photomultiplier to reduce the detector's sensitivity to ambient light, such sensitivity being further reduced by the container, into which the ambient light can pass only through the aperture therein.