Optical timing and A/D conversion method and apparatus

An optical timing and A/D conversion method and apparatus for converting analog signals obtained by movement of a plurality of reaction vessels relative to one or more beams of light from analog to digital signals. The sample signals are obtained each time a reaction vessel passes through a beam of light. The converted digital signals indicate the absorbance of the respective vessels and their contents. Each of the reaction vessels or cuvettes has translucent wall portions providing a radiation path therethrough for the light beams which may be monitored by photometer means in a chemical reaction analyzer. The vessels are repeatedly passed through the light beams of the photometer means as chemical reactions take place therein, the purpose being to monitor the changes in the reaction of the fluids therein by measuring the changes in the absorbance of the vessel and fluids. The sample interval of the analog signal is repeatable for each vessel for each light beam and may be shifted to select the best portion of the analog signal generated as the vessel passes through the particular light beam. The A/D conversion also may eliminate the dark sample or noise error between the light beams and the reaction vessels and may eliminate the variations in the sample signals caused by changes in the rate of relative movement between the beams and vessels and changes in the velocity of the rotating beam.