Patent ID: 7782459

Claim:
An apparatus for measuring average size and concentration of a polydispersed agglomerate of primary particles, the apparatus comprising: a light source configured to emit a beam of light in a first direction; a first light detector positioned at a first angular position, θ 1 , from the first direction of the beam of light, the first light detector being configured to generate a first signal proportional to light scattered onto the first light detector by the polydispersed agglomerate in a probe volume formed in the beam of light; and a second light detector positioned at a second angular position, θ 2 , from the first direction of the beam of light, the second light detector being configured to generate a second signal proportional to light scattered onto the second light detector by the polydispersed agglomerate in the probe volume, wherein an average concentration of the polydispersed agglomerate, C m , per unit total scattered light, P Tθ , is given by: C m P T ⁢ ⁢ θ = f 1 ⁢ f 2 ⁢ C m ⁢ # , where f 1 is a function of optical properties of the primary particles, f 2 is a function of a configuration of the apparatus, and C m # is a nearly invariant first function of a scattering ratio, R θ1/θ2 , of the first signal to the second signal.