An apparatus for measuring particles contained in a sample liquid has a cylindrical cell having an incident light transmitting portion, a transmitted light transmitting portion diametrically aligned with the incident light transmitting portion, and a light transmitting portion at an angle to the diameter...http://www.google.com.au/patents/US4781459?utm_source=gb-gplus-sharePatent US4781459 - Apparatus for measuring the amount of minute particles contained in liquid
