Automatically-adjusting photometer
US4128339A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 6, 1977 |
| Grant date | Dec 5, 1978 |
| Priority date | — |
| Expiry date | Jan 6, 1997 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/27
- WIPO fieldMeasurement
- WIPO sectorInstruments
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.