| 摘要 |
PURPOSE:To enable correction of changes in the sensitivity with limited noise in a broad dynamic range, by adding outputs of a pair of photoelectric elements to control the gain of an amplifier to be inversely proportional to the addition output. CONSTITUTION:Outputs of a pair of photoelectric elements 8a and 8b are converted to voltage with converters 9 and 10 and then, inputted into an adder 11 while one thereof is inputted into a subtractor 12 via a code converter 13. The output of the adder 11 is fed to the base of a transistor 17 to emit light from an LED 16. Then, the gain of an amplifier 14 changes in inverse proportion to light energy I incident into photoelectric elements 8a and 8b. Therefore, the variation portion of the light energy I is cancelled from the signal outputted from the amplifier 1 to obtain the signal proportion to only the refractance index difference DELTAm between the sample solution and the control liquid. |
