Abstract Laser beam L is scattered by particles in the sample cell 1. Photosensor assembly 33 detects forward scattered light and assembly 5 detects sideward and backward scattered light for the purpose of increasing the precision of measurement. Both the photosensor assemblies are temperature-monitored by sensors 6 and 7 to prevent erroneous measurement due to small temperature-dependent zero-level shifts of photosensors used in the photosensor assemblies. If temperature variations of or a temperature difference between the assemblies exceeds a predetermined value, an alarm signal is generated with the measurement interrupted automatically.
An apparatus for measuring a particle size distribution through the measurement of intensity distribution of light rays scattered from particles irradiated with a laser beam, said apparatus comprising: a transparent sample vessel for accepting a fluid medium suspending therein sample particles whose size distribution is to be measured, said transparent sample vessel being irradiated with a laser beam; a first photosensor assembly consisting of a plurality of concentrically arrayed semicircular photosensors for detecting the intensity distribution of light scattered forward by said sample particles; a second photosensor assembly consisting of photosensors for detecting lights scattered at angles larger than the scattering angle of said light scattered forward; a first temperature sensor for sensing the temperature T₁ of said first photosensor assembly; a second temperature sensor for sensing the temperature T₂ of said second photosensor assembly; means for generating an alarm signal when a temperature variation ΔT₁ of said first photosensor assembly, a temperature variation ΔT₂ of said second photosensor assembly or a temperature difference |T₁ - T₂| between said first and said second photosensor assemblies reaches or exceeds a predetermined value.
Claim 2
Dependent Claim
33 words
An apparatus as difined in Claim 1, wherein said second photosensor assembly consists of a photosensor for detecting light scattered at an right angle and of a photosensor for detecting light scattered backward.
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