Automatically-adjusting photometer
First Claim
1. An automatically-adjusting photometer for measuring light absorption of a sample which comprises:
- an optical portion having in combination a light source providing a beam of light, a sample test location, and a photodetector, said light source being constructed to transmit the beam of light through the sample test location so as to strike the photodetector, said photodetector being constructed to transmit an electrical output signal proportional to the intensity of the beam of light;
converting network means for receiving at an input the electrical output signal and converting said output signal to a logarithmic value;
said converting network means including means for selectively reducing said output signal by a predetermined factor prior to conversion to a logarithmic value;
a computer having control and computational modes and a memory portion, said computer in the control mode being constructed to sequentially perform measurment of the logarithmic values of output signals placing these in memory, said computer in the computational mode being constructed to retrieve data stored in memory and calculate the actual absorbance value A of a sample placed in the test location in accordance with the equation A = (Vs - Vo)/(V1 - Vo) where Vo is the logarithmic value of th output signal occurring when the transmission degree of light through the test location is a known reference value between 0 and 1, V1 is the logarithmic value of the output signal of Vo reduced by said predetermined factor, and Vs is the logarithmic value of the output signal occurring when a sample is placed in the test location;
an analog to digital converter connecting an output of said converting network means to a computer input; and
a display apparatus connected to an output of said computer.
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0 Petitions
Accused Products
Abstract
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.
20 Citations
8 Claims
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1. An automatically-adjusting photometer for measuring light absorption of a sample which comprises:
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an optical portion having in combination a light source providing a beam of light, a sample test location, and a photodetector, said light source being constructed to transmit the beam of light through the sample test location so as to strike the photodetector, said photodetector being constructed to transmit an electrical output signal proportional to the intensity of the beam of light; converting network means for receiving at an input the electrical output signal and converting said output signal to a logarithmic value; said converting network means including means for selectively reducing said output signal by a predetermined factor prior to conversion to a logarithmic value; a computer having control and computational modes and a memory portion, said computer in the control mode being constructed to sequentially perform measurment of the logarithmic values of output signals placing these in memory, said computer in the computational mode being constructed to retrieve data stored in memory and calculate the actual absorbance value A of a sample placed in the test location in accordance with the equation A = (Vs - Vo)/(V1 - Vo) where Vo is the logarithmic value of th output signal occurring when the transmission degree of light through the test location is a known reference value between 0 and 1, V1 is the logarithmic value of the output signal of Vo reduced by said predetermined factor, and Vs is the logarithmic value of the output signal occurring when a sample is placed in the test location; an analog to digital converter connecting an output of said converting network means to a computer input; and a display apparatus connected to an output of said computer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification