Biodynamics LLC

Robert H Johnson

Mark D McNeil

Yasuhiro Yamazaki

An automatically-adjusting photometer for measuring the absorbance of a sample in which the amount of light passing through a sample test location is sensed by a photodetector and converted to an electrical output signal. The output signal is amplified and converted to a logarithmic value. Prior to measuring the absorbance of a sample, the photometer is calibrated by a computer. With the sample test location empty, the computer records and places in memory a logarithmic value proportional to the electrical output signal which corresponds to zero absorbance. Next, this value is reduced by a predetermined factor by switching a resistor into the calibration circuitry. The resulting value is also recorded and placed in memory by the computer. When a sample is placed in the test location, the computer records a value proportional to the electrical output signal which corresponds to the absorbance of the sample. Using the three recorded values the computer calculates the correctly-adjusted absorbance of the sample.

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El Toro, CA, United States of America

Robert H Johnson